We just completed statistical analyses of eight years (33 sessions) of data from our Basic Exercise Program. Since 1996, we have conducted exercise classes two or three days a week, almost every hour of the day, in a separate fitness facility, for men and women from 15 to 85 years of age, in accordance with the 1995 American College of Sports Medicine (ACSM) training guidelines. During each 60-minute class period, the six participants perform 20 to 25 minutes of strength exercise (10 Nautilus machines), 20 to 25 minutes of endurance exercise (treadmill or recumbent cycle), and five minutes of stretching exercise all under the watchful eyes of two instructors.

The ACSM strength training guidelines call for one set of each strength exercise, performed with a moderate resistance that permits 8 to 12 controlled repetitions to the point of muscle fatigue for the major muscle groups. The ACSM endurance training recommendations call for a minimum of 20 minutes of continuous aerobic activity at about three-quarters effort (typically 70 to 80 percent of maximum heart rate), with 2 to 3 minutes of lower effort warm-up exercise and 2 to 3 minutes of lower effort cool-down exercise. The ACSM flexibility training guidelines call for static stretches of at least 20 seconds duration for the major muscle groups.

Our results have demonstrated that these basic exercise guidelines are highly effective for improving our participants’ body weight, body composition and blood pressure, as well as for enhancing a variety of fitness parameters (muscle strength, joint flexibility, balance, etc.) On average, after 10 weeks of the Basic Exercise Program, our class members add three pounds of lean (muscle) weight, lose 4.5 pounds of fat weight, reduce their systolic blood pressure by 4 mmHg and their diastolic blood pressure by 3 mmHg. These are very beneficial physiological adaptations to a short term program of relatively brief exercise sessions.

Of the almost 1800 study subjects, there were no significant response differences among the younger, middle-aged or older exercisers. That is, regardless of age, the class members made essentially equal improvements in body weight, body composition and blood pressure from participating in the Basic Exercise Program.

Personalized Weight Reduction Program
In addition to our Basic Exercise Program we offer a more personalized weight reduction program using essentially the same strength, endurance and flexibility exercises, but with one-on-one instruction during each training session. In a recent study, we divided the program participants into two groups. Group A met weekly with a nutrition counselor and followed a basic dietary plan. Group B also followed a basic dietary plan, but did so on their own without a nutrition counselor.

The Group A participants, who met weekly with a nutrition counselor, had a 100 percent program completion rate and a 100 percent diet adherence rate. The Group B participants, who did not meet with a nutrition counselor, had less than a 70 percent program completion rate and less than a 30 percent diet adherence rate.

Interestingly, Group A participants lost 8.5 pounds of fat and added 2.0 pounds of muscle for a 10.5-pound improvement in their body composition, whereas Group B participants lost 3.5 pounds of fat and added 1.5 pounds of muscle for a 5.0-pound improvement in their body composition.

These results revealed that the weight loss participants who interacted with a nutrition counselor (once a week) had a greater program completion rate (100% vs. 67%), a greater diet adherence rate (100% vs. 29%), and a greater improvement in body composition (10.5 lbs. vs. 5.0 lbs.). Apparently, people who want to lose fat are more likely to succeed if they meet with a nutrition counselor for encouragement, accountability, feedback and reinforcement.

Research is clear that the most effective means for losing fat (as well as for replacing muscle and recharging your metabolism) is the combination of a sound exercise program and a sensible diet plan. It is also evident that the exercise program may be more productive with a fitness instructor, and that the diet plan may be more successful with a nutrition counselor.

Computerized Weight Reduction Program
Our latest approach to weight loss incorporated the Basic Exercise Program, but with a Remote Trainer Option (Internet Communications) following the initial instructional period, and with a computerized coaching and recording system for entering exercise and nutritional information on a daily basis.

Using the HealtheTech system, participants completed a lifestyle survey, had their resting metabolic rate measured using the hand-held BodyGem® device, utilized a personalized weight loss plan created with BalanceLog® Pro software, and entered both the individual exercises they performed and the foods they ate with Balance Log® on their computer to determine their daily calorie balance. The reports generated by BalanceLog Pro were emailed from the remote trainer with specific topics and behavior change skills to individual participants on a weekly basis. Although some computer experience is helpful, and a weekly meeting with an exercise/nutrition counselor is advisable, the BalanceLog software provided educational and motivational information enabling the participants to make positive lifestyle changes with their nutrition and exercise plans.
For example, a middle-aged medical doctor lost 17 pounds during the 12-week training period. That is, she reduced her bodyweight by 1.4 pounds per week, slightly more than her recommended weight loss rate of 1.0 pound per week. Her efforts resulted in almost a one-point-per-month reduction in percent body fat (approximately 31 percent fat to 28 percent fat), and a major improvement in resting blood pressure (128/92 mm Hg to 110/82 mm Hg).

Although her enthusiasm for the program led to a little faster weight loss than the computer feedback advised (resulting in a slight reduction in lean weight and resting metabolic rate), she can only be commended for such excellent improvements in body weight, body composition and blood pressure. We are convinced that modern computer technology can be a most valuable tool for sensible weight loss, both in the areas of activity adherence and dietary accountability. Combining a basic exercise program and a personalized nutrition plan based on measured resting metabolic rate with good instructors/counselors and precise computer monitoring seems to be a highly productive approach for improving bodyweight/body composition and physical fitness in previously overweight/sedentary individuals.

Our studies with several thousand beginning exercisers has consistently shown single-set strength training to be highly effective for improving body composition, increasing muscle strength and reducing resting blood pressure. This is important from a practical perspective because many time-pressured people do not have time to perform multiple sets of each strength exercise.

Eventually, however, standard single-set strength training leads to a strength plateau, requiring some change in the exercise program to stimulate additional muscle development. Such a change could involve more training exercises or more training sets. Unfortunately, both of these alternatives require more training time. For example, performing twice as many exercises requires twice as much training time, and performing two sets of each exercise requires at least three times the training duration, due to the necessary rest period between successive sets of the same exercise.

One time-efficient means for enhancing the strength-building stimulus is known as high-intensity training. Unlike multiple-set training that repeats the exercise bouts, high-intensity training is designed to make each exercise bout more productive. This is typically accomplished by extending the exercise set with a few post-fatigue repetitions to involve more muscle fibers and increase the tissue microtrauma.

A simple means for extending the exercise set is to fatigue the target muscles with your standard weightload, then immediately reduce the resistance by 10 to 20 percent and complete as many additional (post-fatigue) repetitions as possible. For example, let’s say you can perform 10 leg extensions with 100 pounds. At this point, your quadriceps muscles are too fatigued to do another repetition with this weightload. However, if you quickly reduce the resistance to 85 pounds, you should be able to complete three to five more repetitions with the lighter weightload. This extended exercise set has produced two progressively more impactful levels of muscle fatigue with relatively heavy weightloads, all within the parameters of the anaerobic energy system (90 seconds). This high-intensity technique is known as breakdown training because you break down the resistance in accordance with your pre-fatigued level of muscle strength to enable a few post-fatigue repetitions.

A similar high-intensity technique is called assisted training, because an assistant helps you to complete the post-fatigue repetitions. Using our previous example, you have just completed 10 leg extensions with 100 pounds and you cannot perform another repetition on your own. At this point, an instructor manually assists you in the lifting phase of an 11th repetition. Because muscle force output is about 40 percent greater in lengthening (eccentric) actions than in shortening (concentric) actions, no assistance is necessary on the lowering phase of the post-fatigue repetitions. Usually, three to five assisted repetitions are sufficient to achieve a high-level of muscle-building stimulus.

Our many studies examining the effects of high-intensity strength training have consistently revealed excellent results using these and other high-intensity techniques (e.g., pre-exhaustion training, slow-speed training, triple-eight training). In one research program with 48 participants, six weeks of high-intensity training produced an 18-pound increase in muscle strength (average for 12 previously plateaued training exercises), a 2.5-pound increase in lean (muscle) weight, and a 3.5-pound decrease in fat weight.

Fortunately, these highly-reinforcing results were attained from just two weekly exercise sessions of less than 30 minutes each. Unlike performing more exercises or additional exercise sets, the high-intensity training sessions increased the participants’ standard workout duration by only a few minutes. Although time-efficiency is certainly a practical advantage of high-intensity strength training, the major benefit is effectiveness. Almost half of the professional football teams in the NFL use high-intensity training programs to maximize the players strength/muscle development.

Over the years, we have tried many approaches for offering our members opportunities to do high-intensity strength training. Most often we have provided small group sessions or special classes at specific times and places. Unfortunately, it has not always been convenient for members to participate in these high-intensity training programs.

Recently, we have expanded opportunities for supervised high-intensity training sessions to most hours of our fitness facility operation. We have trained several key instructors in high-intensity techniques and allowed interested members to work with them one or two days per week. The participants pay a reasonable fee for these one-on-one exercise experiences (eight weeks, once a week for $60; eight weeks, twice a week for $110), and the instructors receive a higher pay rate ($5 more than their standard hourly rate), which seems to be satisfactory for everyone involved.

Although this is not a high-revenue program for the YMCA, it appears to be the best means for member retention that we have tried. Rather than stagnating on a strength plateau, losing training motivation, and possibly leaving the Y, more and more members look forward to participating in these advanced strength training programs. The time-efficiency, instructor interaction and excellent results make our high-intensity strength training program popular among members, and their renewed exercise enthusiasm has a profound positive effect on our fitness center operation.

A few years ago, we conducted a research study with elderly residents of a large nursing home in Orange City, Florida. The 20 study subjects averaged almost 90 years of age, and spent most of their waking hours in wheelchairs. Their major problem was physical frailty, which we sought to address through a basic and brief program of regular strength training. Our major challenge was to get them out of their wheelchairs, and we selected four weightstack machine exercises that effectively served this purpose. However, our fifth exercise was the neck machine to strengthen the muscles that were supposed to hold their heads erect.

We included the neck machine because these frail older adults were almost incapable of lifting their chins off their chest. Due to incredibly weak neck muscle that could no longer hold their heads erect, these seniors had more difficulty breathing, eating, drinking and looking forward, as well as considerable discomfort in their neck/shoulder area.

After 14 weeks of strength training (1 set of 8 to 12 repetitions of the 5 exercises twice a week), the subjects added 4 pounds of muscle, lost 3 pounds of fat, increased their leg strength by 80 percent, increased their upper body strength by 40 percent, improved their functional capacity (FIM score) by 14 percent, and spent much less time (if any) in their wheelchairs. However, in our opinion, the most impressive outcome of the study was the renewed ability of the participants to hold their heads erect. In their opinion, the best result of the strength training program was the reduced discomfort in their necks and backs (we also included the low back machine in the five exercise training protocol).

Because an average-sized head weighs between 12 and 15 pounds, the neck muscles are extremely important for maintaining proper head position whether we are walking, standing or sitting. Strong neck muscles are our basic defense against the force of gravity that constantly works to pull our heads downward and forward. When our heads spend too much time in the downward/forward position, we typically experience a variety of undesirable degenerative problems (and discomfort) in our musculoskeletal system.

In addition to reducing the risk of chronic neck problems, strong neck muscles help protect us from traumatic neck injuries, such as severe whiplash from rear-end car accidents. Athletes who play contact sports, such as football, basketball, soccer, lacrosse, hockey, rugby and baseball are also at a greater risk for neck injuries. So are sports participants who have a higher probability of falling, including gymnasts, skaters, skiers, rock climbers, horseback riders and cyclists.

Even people who are completely sedentary can benefit from strong neck muscles, because muscle condition and bone condition are closely related. With progressive resistance exercise, neck muscles add myoproteins to become stronger. The same training stress is transmitted through the tendons to the bones, which likewise add collagen proteins to become stronger and more resistant to osteoporosis and other degenerative processes.

Unfortunately, most people pay no attention to neck strengthening exercises. Their necks gradually become weaker and weaker, and the cervical vertebrae inevitably do the same. How sad to see so many middle-aged women (and men) with an uncomfortably curved neck, forward head, and humped shoulders.

Although perhaps not as serious, unconditioned necks are typically unattractive. They seam weak, frail, and barely able to support the head in an upright position. Whether they appear too thin or too fat, poorly conditioned necks are hard to hide as this part of the anatomy is exposed even when wearing a suit or dress.

Obviously, weak neck muscles fatigue sooner than strong neck muscles. As a result many office workers feel like putting their heads on their desks to rest their necks during the afternoon hours.
A few years ago we tested several executives for neck extensor strength before work (9:00 a.m.) and after work (5:00 p.m.). Although they spent their entire work day sitting at a desk, their neck extensor strength decreased by over 30 percent during those eight hours. Even when sitting still, their neck muscles were working (and fatiguing) hour after hour. Of course, persons with well-conditioned neck muscles will also become weaker as the day progresses, but they may still be stronger at 5:00 p.m. than most people are at 9:00 a.m. Most likely, they will also be more productive at their job, as their task attentiveness is not reduced by neck fatigue and discomfort.

Maintaining strong neck muscles is important for a variety of other reasons. For example, riding a 10-speed bicycle places considerable tension on the neck extensor muscles to keep the head in road-viewing position. Weakness in these muscles leads to premature fatigue as well as an uncomfortable cycling experience.

Swimming uses a lot of neck movement to turn or lift the head for breathing purposes. Well-conditioned neck muscles are especially important for the butterfly and breast strokes, but contribute to successful swimming in the other strokes as well.

Strong neck muscles are also associated with performance ability in striking skills such as driving a golf ball, serving a tennis ball and hitting a baseball. To accurately strike a ball, it is important to keep the head as still and stable as possible so the eyes can focus clearly on its center.

In my opinion the neck and lower back muscles represent the two most important areas of the body from a conditioning perspective. Because the neck muscles control head movements, they are essential for normal and athletic functions. Because the neck muscles protect the cervical vertebrae and spinal nerve trunk, they are critically important for injury prevention. For these reasons, I strongly recommend that fitness instructors, personal trainers and strength coaches include neck strengthening exercises in their clients’/athletes’ exercise programs.

The safest approach to overall neck strengthening is a four-way neck machine, although it is not necessary to perform all four movements. Neck extension is the most important training exercise as these muscles (upper trapezius, levator scapulae and splenius) hold the head erect against the force of gravity. Neck flexion is second in importance, and actually uses the same muscles (sternocleidomastoids) working together that function independently to move the head laterally (left side or right side).

Generally speaking, one set of neck extensions and neck flexions should be sufficient, performed twice a week. I recommend 10 to 15 slow and controlled repetitions of each neck exercise, performed through a comfortable range of movement. When 15 repetitions can be completed with excellent technique (no momentum or body movements), the resistance should be increased by five percent (or less).

Of course, due to the possibility of previous injuries, pre-existing conditions, or other contraindications, clients should have physician approval prior to performing neck strengthening exercises. On the other hand, we are unaware of any injuries in our facilities over the past 20 years resulting from use of our neck machines. In fact, most of our members, program participants, and research subjects would agree that they have experienced more benefit from the neck and back exercises than from any of the other strength training components.

Importance of Resistance Training
Men and women who do not perform regular resistance exercise experience progressive muscle atrophy throughout the aging process. Research indicates that inactive adults lose about one-half pound of muscle per year during their 30’s and 40’s (5, 8). The rate of muscle loss may double to one-pound per year in people past 50 years of age (13). Unfortunately, the higher rate of fat gain masks the muscle loss. Adults typically lose about 5 pounds of muscle and add about 15 pounds of fat each decade during the midlife years.

Based on bodyweight the average adult changes approximately 10 pounds per decade, but based on body composition the average adult changes approximately 20 pounds per decade (5 pounds less muscle and 15 pounds more fat). A woman in her 50’s may have 15 pounds less muscle and 45 pounds more fat than she had in her 20’s. This represents an unhealthy 60-pound change in her body composition, which increases her risk for a variety of devastating degenerative problems such as cardiovascular disease, many types of cancer, type II diabetes, and low back pain.

While the focus is typically on fat loss (one out of two American adults is presently on a weight reduction diet plan), more emphasis should be placed on muscle gain. This is due to the fact that the 5-pound per decade loss of muscle is largely responsible for up to a 5 percent per decade reduction in resting metabolic rate (5, 12). A slower resting metabolism means that some calories previously used by high-energy muscle tissue are no longer needed, and are therefore stored as fat. Because a pound of muscle requires between 35 to 50 calories a day for tissue maintenance, a 10-pound muscle loss may reduce resting metabolism by 350 to 500 calories daily (4, 14). Think of cutting your daily food intake by 20 to 25 percent, and you will better appreciate the importance of muscle and metabolism.

Although eating fewer calories can prevent weight gain, it cannot reduce the rate of muscle loss or metabolic slowdown. It is obviously more desirable to maintain both muscle and metabolism, as well as the functional capacity to perform physical activities. Progressive resistance exercise can build muscle tissue that facilitates physical performance and enhances energy utilization throughout the senior years. In fact, strength training is the only type of exercise that can maintain muscle and metabolism as we age, and should therefore be the essential component of every senior fitness program.

Fortunately, older adults can rather quickly rebuild muscles that have atrophied from years of sedentary living. Research has repeatedly shown significant increases in muscle mass 3, 7, 9, 10, 13, 18) and resting metabolic rate (4, 15) in seniors who do regular resistance exercise. Senior research subjects at Tufts University (4) and the University of Maryland (15) added 3.0 to 3.5 pounds of muscle and increased their resting metabolism by 6.8 to 7.7 percent after 3 to 4 months of standard strength training.

We recently conducted a large-scale strength training study with 1,132 men and women between 20 and 80 years of age (18). The younger adults (21-40 years), middle-aged adults (41-60 years) and older adults 61-80 years) made similar improvements in bodyweight, percent fat, fat weight and lean (muscle) weight after 8 weeks of basic resistance exercise.

It is interesting to note that adult and senior men add about 3 to 4 pounds of lean (muscle) weight after 2 to 3 months of strength exercise (15, 17, 18), whereas adult and senior women gain about 2 to 3 pounds of lean (muscle) weight over the same training period (3, 18). Although the rate of improvement is almost the same, men typically replace more muscle than women during a given time period because they generally have greater body mass.

On average, previously sedentary seniors can replace approximately 3 pounds of muscle after about 3 months of regular resistance exercise. Further, 3 pounds more muscle tissue increases resting metabolic rate by approximately 7 percent in older adults. Additionally the senior exercisers in these studies averaged about 50 percent greater muscle strength after completing their training program. Research clearly confirms the importance of resistance training for effectively reversing the muscle loss, metabolic slowdown, and strength decrement associated with the aging process.

There are many more health-related reasons why seniors should perform regular resistance exercise. As presented in the March 2002 issue of Fitness Management YMCA Quarterly, strength training can reduce the risk of cardiovascular disease, colon cancer, diabetes, osteoporosis, low back pain and depression (19).

Principles of Strength Training
Generally speaking, the guidelines for healthy senior strength exercisers are essentially the same as those for younger adults and youth. Basically, a well-designed strength training program for any age group consists of several exercises that address all of the major muscle groups. Studies with older adults have used as few as 5 exercises and as many as 15 exercises. For example, a landmark study with older women (13) incorporated only the leg press, leg extension, pulldown, back extension and abdominal curl exercises, whereas a classic study with senior golfers (17) included the leg extension, leg curl, hip adduction, hip abduction, leg press, chest cross, chest press, pullover, lateral raise, biceps curl, triceps extension, low back extension, abdominal curl, neck flexion, and neck extension exercises.

Sets
Most senior strength training studies have used a one, two or three set training protocol. Typically, programs with fewer exercises perform multiple sets, and programs with more exercises perform single sets. For example, participants in the older women study (13) performed 3 sets each of the 5 resistance exercises, whereas participants in the senior golfers study (17) performed one set each of the 15 resistance exercises. Participants in both programs completed 15 exercise sets per session, which represents a reasonable recommendation for most senior strength training protocols.

In a recent meta-analysis of several strength training studies, all but one showed no significant difference between performing single or multiple sets of resistance exercise (6). The researchers therefore concluded that training with one, two or three sets per exercise is equally effective for strength development and largely a matter of personal preference.

Based on the research protocols used with senior subjects and the comparative studies on exercise sets, a standard strength training session for older adults may include 8 to 24 sets of exercise. The following guidelines represent a sensible approach for training sets based on the number of exercises performed:

• 4 to 8 exercises……………………………………………. 2 to 3 sets each
• 8 to 12 exercises…………………………………..……… 1 to 2 sets each
• 12 to 16 exercises………………………………………… 1 set each

Generally speaking, older adults should take at least two minutes recovery time between successive sets of exercise. This time period permits almost full replenishment of the anaerobic energy source used during strength training.

Resistance and Repetitions
There is an inverse relationship between the amount of resistance used and the number of repetitions performed. The productive resistance range for strength development is generally considered 60 to 90 percent of maximum resistance, with a standard recommendation of approximately 75 percent of maximum resistance (2, 16). Research indicates that most adults can complete between 8 and 12 repetitions with 75 percent of their maximum resistance, and the majority of senior strength training studies have incorporated this exercise protocol (4, 7, 9, 13, 17, 18).

Although 8 to 12 repetitions with 75 percent of maximum resistance has proven to be a safe and productive strength training protocol for men and women between 50 and 90 years of age, the American College of Sports Medicine recommends that seniors perform 10 to 15 repetitions per set with slightly less resistance (1). This more conservative training approach is most appropriate for beginning exercisers. However, as higher levels of strength fitness are attained, most seniors can safely progress to lower repetition exercise protocols. The textbook, Strength Training for Seniors, recommends the following training progressions for seniors who prefer to use heavier resistance (16).

• Beginner Exercisers 12 to 16 repetitions with about 65 percent
  of maximum resistance.

• Intermediate Exercisers 8 to 12 repetitions with about 75 percent of maximum resistance.
• Advanced Exercisers 4 to 8 repetitions with about 85 percent of
  maximum resistance, periodically.

Progression
The key factor in strength development is progressive resistance. For continued progress, seniors must gradually increase the training load as the muscles become stronger. A safe approach to more challenging training sessions is known as the double progressive program, in which clients increase the number of repetitions before they increase the exercise resistance. For example, seniors following an 8 to 12 repetition protocol should use the same resistance until they can complete 12 good repetitions, at which point they should increase the resistance by 5 percent or less.

Technique
The two major factors in exercise technique are movement speed and movement range. Although research has not revealed an optimal speed for strength training, studies with senior subjects have incorporated relatively slow movement speeds, typically averaging about 6 seconds per repetition (13, 18). At about 6 seconds per repetition, a set of 10 repetitions requires approximately one-minute of continuous muscle action/tension, which provides a productive stimulus for strength development (16). Because slower movement speeds involve less momentum they provide more controlled and consistent stress to the musculoskeletal system, thereby reducing the risk of injury.
Seniors should develop strength throughout the full-range of every joint action, if they can do so without discomfort. Research indicates that full-range strength requires full-range repetitions, as strength gains are specific to the exercise movement patterns (11). Consequently, most strength exercises should be performed throughout the full-range of pain-free movement to maximize muscle development and maintain joint integrity.

Frequency
Strength training is recommended on non-consecutive days, as the muscle microtrauma that results from resistance exercise generally requires about two recovery days for tissue remodeling and strength building (1). Research with more than 1,100 adults and seniors showed more muscle development from three-day-per-week training than from two -day-per-week training (18). However, the difference was relatively small (about 10%), indicating that twice-a-week strength training is highly effective.

Based on the available research, two or three strength training sessions per week are recommended for senior exercisers, dependent upon lifestyle factors and personal preferences. Ideally, the weekly strength workouts should be as evenly spaced as possible. For example, seniors who train three times a week may follow a Monday-Wednesday-Friday schedule, whereas those who train twice a week may exercise on Mondays and Thursdays.

Breathing
Seniors must make sure to breathe continuously when performing resistance exercise. For best results, they should exhale during each lifting movement and inhale during each lowering movement. If you notice them holding their breath, reduce the weightload so that they breathe continuously throughout every repetition.

For as long as I can remember, coaches and fitness professionals have debated the merits of single versus multiple-set strength training. I have personally trained in both manners, and I have conducted numerous research studies on the effects of single and multiple-set exercise protocols. In all of my experiences and experiments, I have found no significant differences between these two training methods.

Consider our most frequently referenced study with 77 intermediate level strength participants who trained 3 days a week for 10 weeks with assisted bar-dips (pectoralis major, anterior deltoids, and triceps muscles) and assisted chin-ups (latissimus dorsi, and biceps muscles). Group One did 1 set of bar-dip and 1 set of chin-ups, Group Two performed 2 sets of bar-dips and 2 sets of chin-ups, and Group Three completed 3 sets of bar-dips and 3 sets of chin-ups. Groups Two and Three rested 2 minutes between successive sets of each exercise.

After 10 weeks of training, all three groups were assessed for their improvement in bar-dip and chin-up performance, tested with bodyweight. Group One experienced an average bar-dip/chin-up increase of 4.8 repetitions, Group Two increased their average bar-dip/chin-up score by 4.1 repetitions, and Group Three had an average improvement of 5.2 bar-dip/chin-up repetitions. Statistically, there were no significant differences among the single, double and triple-set training protocols.

A classic follow-up study conducted at the University of Florida revealed similar results. After 14 weeks of strength training the knee extension and knee flexor muscles with leg extensions and leg curls, the 38 subjects recorded almost identical average strength gains regardless of performing 1 set or 3 sets of each exercise (14.5% increase vs. 15.5% increase).

Although dozens of other studies have shown similar strength benefits from single and multiple set training, a recent meta-analyses of more than 100 studies indicated that 4 sets of exercise (targeting a specific muscle group) may be the most effective strength-building protocol. Ignoring the methodological problems associated with meta-analyses, performing 4 sets of each exercise presents two practical problems for many people, namely time availability and physical ability.

For example, time-pressured men and women may have difficulty spending approximately 10 minutes at each exercise station (4 sets of 1 minute each with 2 minutes recovery time between sets). At this rate, 12 exercises would require about 2 hours for completion, compared to about 25 minutes for a single-set training protocol.

For others, particularly previously sedentary, deconditioned, and elderly individuals, 4 sets of each exercise may be simply too physically demanding. Although they may be able to gradually progress to higher volume training programs, they would be well-advised to begin with 1 good set of each exercise.

Our research with more than 1100 beginning participants (previously inactive adults between 20 and 80 years of age) featured 1 set (8 to 12 repetitions) of 10 exercises, performed 2 or 3 days a week for a period of 8 weeks. This 20 minutes per session strength training program has produced significant increases in lean (muscle) weight and significant decreases in fat weight. As shown in Table 1, the men averaged almost 4 pounds more lean weight and 7 pounds less fat weight, and the women averaged almost 2 pounds more lean weight and 4 pounds less fat weight. These results compare favorable with all other published studies on beginning strength training, regardless of the number of sets or exercises performed.

Table 1. Body composition changes following 8-weeks of single-set strength training (1132 subjects).

As participants continue training, they eventually encounter a strength plateau. When single-set exercise sessions no longer elicit further progress in strength or muscle development, a change in the training protocol becomes necessary. One means for increasing the training stimulus is a higher volume exercise program involving more sets, more exercises, or both. At this point, in their training, participants should be capable of performing higher volume strength training sessions, but they may not have the time to do so.

If time constraints prohibit multiple-set training, plateaued participants can enhance their single-set exercise sessions with high-intensity training techniques. Generally, these advanced training procedures require a few post-fatigue repetitions immediately following your standard exercise set. This is typically accomplished through breakdown repetitions (reducing the resistance by 10 to 20% at the point of temporary muscle failure and completing as many additional repetitions as possible) or assisted repetitions (having a partner assist in the lifting phase of additional repetitions upon experiencing temporary muscle failure).

Although adding less than 30 seconds to the extended exercise set, high-intensity training techniques have proved highly effective in our studies for the U.S. Navy. In the athletic arena, 12 of the professional football teams in the NFL presently use single-set, high-intensity strength training protocols.

Although essentially everyone should do strength training, relatively few people really enjoy doing it. If you are like me, you look forward to every strength workout, but we are definitely in the minority (a reasonable estimate is that about 5 to 10 percent of Americans do some form of strength exercise). While we would be perfectly happy spending a couple hours a day in the weightroom, most of us just don’t have the time to do so. Fortunately for us, and for all those who don’t particularly like either free-weights or weightstack machines, single-set training (alone or with high-intensity techniques) offers a safe, effective, and time-efficient option for strength and muscle development.

According to the Centers for Disease Control, approximately 90 percent of American adults are so sedentary they could almost be reclassified as statues (1). It should therefore come as no surprise that obesity has increased by almost 70 percent in the past 10 years (12% to 20%). Nearly 60 percent of all adults in this country are overweight, and the percentage of obese children has doubled since the 1980’s. In addition to higher risk for heart disease and various types of cancer, obesity raises the risk of diabetes 10 times for men and 20 times for women (2).

Unfortunately, being overweight is merely the tip of the iceberg when it comes to body composition concerns. Sedentary adults typically add 10 pounds of bodyweight every decade during the midlife years. However, this unfavorable weight change results from a 5-pound loss of muscle and a 15-pound gain in fat. In other words, what appears to be a 10-pound weight problem is actually a 20-pound body composition problem (3).

In addition to adversely affecting personal appearance and physical performance, the reduction in muscle tissue is largely responsible for metabolic slow-down. The 5-pound per decade muscle loss is closely associated with a 5-percent per decade decrease in resting metabolic rate (4).

Even people who don’t increase their food intake experience creeping obesity, because calories previously used to maintain more muscle tissue are now placed in fat storage areas of the body.
Most Americans know that they are adding fat, but few realize that they are losing muscle. What’s more, they don’t understand that muscle loss is a major factor in fat gain. If they did, they wouldn’t place such a strong emphasis on dieting. With one out of every two adults presently following a low-calorie diet plan, we need a major teaching effort from health and fitness professionals to remedy this situation.

Although dieting can reduce fat, it cannot replace muscle to solve the primary body composition problem. In fact, low-calorie diets actually result in muscle loss, which accounts for approximately 25 percent of the total weight lost (5).

Fortunately, more overweight adults are complementing their diet plan with aerobic activity (usually walking) that burns additional calories and enhances cardiovascular fitness. While this combined program of diet and endurance exercise attenuates muscle loss, it does not add muscle or increase resting metabolic rate.

The missing component, of course, is strength training which does replace muscle tissue and recharge resting metabolism. Studies show that 25 minutes of standard strength training, two or three days a week, can increase previously inactive adults’ muscle mass by about three pounds in two to three months of training (6,7,8,9). What’s more, research reveals that three pounds of new muscle tissue increases resting metabolism by 6 to 8 percent, which represents an additional 100 to 120 calories per day (8,9).

Health Benefits of Strength Training
Strength training is the best means for attaining and maintaining a desirable body composition, as well as for developing a high level of musculoskeletal fitness. However, there are many other health-related reasons for performing regular resistance exercise. Consider the following medical benefits associated with sensible strength training.

Reduced Risk of Osteoporosis
The effects of progressive resistance exercise are similar for muscle tissue and bone tissue. The same training stimulus that increases myoproteins in muscle increases collagen proteins in bone. Researchers have reported significant bone mineral density development in older men (10) and women (11) who participated in standard strength training programs.

Reduced Risk of Type II Diabetes
One of the fastest growing health problems in the United States is diabetes, which presently affects 15 million American adults (2). Type II diabetes begins with a deficient glucose metabolism, which hinders the transfer of glucose from the blood to the muscles. Researches at the University of Maryland found that four months of regular strength training increased glucose uptake by almost 25 percent in the pre-diabetic study subjects (12). Their improved glucose metabolism improved the participants’ potential for avoiding type II diabetes.

Reduced Risk of Colon Cancer
Another University of Maryland study examined the effects of strength exercise on the transit time for food to pass through the gastrointestinal system (13). After just three months, the resistance trained subjects showed a 56 percent faster transit speed. This is a significant finding, because faster gastrointestinal transit time is associated with lower risk for colon cancer.

Reduced Rick of Cardiovascular Disease
Cardiovascular disease is the leading cause of death in the United States, and two primary predisposing factors are high blood pressure and high blood cholesterol. Contrary to popular misconception, properly performed strength exercise leads to lower resting blood pressure readings (6,14). In a study with almost 800 subjects, resting blood pressure was reduced about 4 mm Hg systolic and 3 mm Hg diastolic after just two months of combined strength and endurance exercise (7).

Likewise, researchers have found favorable effects on blood lipid profiles after several weeks of strength training (15,16). In fact, comparative studies have shown as much improvement in blood lipid profiles resulting from strength training as from endurance exercise.

Reduced Risk of Low Back Pain
As you are probably aware, about 80 percent of all Americans will experience low back pain during their lifetime. Fifteen years of research conducted at the University of Florida Medical School has indicated that the largest percentage of low back problems are related to weak low back muscles. Their studies have featured full-range strength exercise for the lumbar spine muscles, and the majority of their subjects have been pain-free or significantly improved after an average 10 weeks of training (15).

Reduced Risk of Depression
A recent study conducted at Harvard University placed clinically depressed seniors into one of two treatment groups (16). One group received educational counseling, while the other group performed three strength training sessions a week with no other intervention. The seniors who did strength exercise experienced significantly better results, with over 80 percent no longer meeting the criteria for depression after only 10 weeks of training.

Teach to Reach
Most adults and seniors are unfamiliar with strength exercise and uninformed regarding the health/wellness benefits of resistance training. They typically associate strength
training with bodybuilders and football players, and see no practical application to their own lives. However, when they understand the many ways in which strength exercise can enhance their personal health, increase their physical fitness, improve their overall appearance and reduce their risk of degenerative diseases, they are more likely to become strength program participants.

We use every means we can to present strength training information to the people (young and old) in our communities. These include television shows, radio spots, newspaper articles and local presentations (service clubs, senior centers, church groups, etc.). Getting the word out is the first step towards getting the people in, and the benefits of sensible strength exercise apply to just about everyone.

In one of our most interesting research studies (7) we investigated how many repetitions people could perform with 75% of their maximum resistance (1RM weightload) in a standard chest exercise (10 degree chest machine). The majority of our 141 subjects completed between 8 and 12 repetitions with 75 percent of their 1RM weightload, the average being 10 repetitions.

This is representative of most men and women, who have a fairly even mix of fast-twitch and slow-twitch muscle fibers in their major muscle groups (e.g., quadriceps, pectoralis major, etc.). That is, most people possess moderate endurance muscles that lose about 2.5 percent of their starting strength every repetition during a challenging set of resistance exercise. In other words, when you can no longer lift 75 percent of your maximum resistance you have reduced your starting strength by 25 percent, and if that occurs in 10 repetitions your strength loss is 2.5 percent per rep (25 % divided by 10 reps = 2.5 percent/per rep).

However, you will note that a couple subjects could compete only 5 repetitions with the same relative resistance (75% of 1RM). These were power athletes (sprinter and thrower) who have inherited a relatively high percentage of fast-twitch muscle fibers and low muscle endurance. Although typically very strong they fatigue quickly, losing about 5 percent of their starting strength every repetition (25% divided by 5 reps =5 percent/rep). These individuals respond better to fewer repetitions per set to match their strength training protocol to their muscle physiology.

You will also observe that one subject performed almost 25 perfect repetitions with the same relative weightload (75% of 1RM). This young lady was an outstanding endurance athlete (winner of the Iron Man Triathlon) who inherited an extremely high percentage of slow-twitch muscle fibers and high muscle endurance. Remarkably, she reduced her starting strength by only 1 percent each repetition (25% divided by 25 reps = 1 percent/rep).

Generally speaking, the number of repetitions you can perform with 75 percent of your maximum resistance is genetically determined by your percentage of fast-twitch (low endurance) and slow-twitch (high endurance) muscle fibers. Most of us have moderate endurance muscles that respond productively to strength training protocols between 5 and 15 repetitions per set. Power athletes have low endurance muscles that respond better to strength training protocols with fewer repetitions per set (e.g., 3 to 7 reps). Conversely, endurance athletes have high endurance muscles that respond better to strength training protocols with more repetitions per set (e.g., 13 to 17 reps).

Specific Repetition Ranges
Although a very small percentage of people possess predominantly fast-twitch or slow-twitch muscle fibers, most of us have moderate endurance muscles that can be effectively trained through a range of repetitions that produce muscle fatigue within the anaerobic energy system. For practical purposes, let’s designate the anaerobic energy system as 20 to 90 seconds of high-effort muscle exercise. At controlled movement speeds of about 6 seconds per repetition (2 seconds lifting and 4 seconds lowering) 3 repetitions take about 20 seconds and 15 repetitions require about 90 seconds.

When you consider that the recommended time frame for aerobic activity is 20 to 60 minutes (1), the 70-second range for anaerobic exercise is extremely brief. Nonetheless, we frequently hear that 3 to 5 repetitions (18 to 30 seconds) are best for developing muscle power, 6 to 8 repetitions (36 to 48 seconds) are best for improving muscle strength, 9 to 11 repetitions (54 to 66 seconds) are best for increasing muscle size, and 12 to 15 repetitions (72 to 90 seconds) are preferred for enhancing muscle endurance. Although these apparently arbitrary anaerobic exercise classifications have long been considered general knowledge and standard procedures, there is little research to support their application.

On the other hand, several studies (2,3,5,6,8) have demonstrated no differences in strength development when training with low or high repetitions, provided that each exercise set fatigues the target muscles within the anaerobic energy system (approximately 20 to 90 seconds). Consider two of these studies completed in the past two years.

Study One
Chestnut and Docherty (3) divided 19 previously untrained men (mean age 24 years) into two exercise groups. One group performed 6 sets of 4 repetitions each and the other group completed 3 sets of 10 repetitions each, 3 days a week for a period of 10 weeks. The training exercises were the triceps bench press, triceps pressdown, barbell curl and dumbbell curl. All of these subjects were assessed for changes in their muscle strength (1RM) and muscle size (cross-sectional area). The researchers reported that both the 4-repetition training and the 10-repetition training elicited statistically significant and equal increases in muscle strength and muscle size. These findings suggest that shorter and longer bouts of high-effort resistance exercise produce similar results when muscle fatigue occurs within the anaerobic energy system.

Study Two
The second study (8) was conducted at the South Shore YMCA, and placed 44 previously untrained men and women (mean age 53 years) into two exercise groups. One group performed each resistance exercise for 1 set of 6 to 8 repetitions and the other group performed each resistance exercise for 1 set of 13 to 15 repetitions. The training exercises were the leg extension, leg curl, chest cross, chest press, pullover, lateral raise, biceps curl, triceps extension, low back extension, abdominal curl, neck flexion and neck extension. After 10 weeks of training, the 22 subjects who did about 7 repetitions per set averaged a 14.4–pound strength gain, and the 22 subjects who did about 14 repetitions per set averaged a 15.0-pound strength gain. Both training groups experienced statistically significant and essentially equal increases in muscle strength. Like Chestnut and Docherty’s research, our study showed no difference in the physiological adaptations associated with lower and higher repetition protocols when training to momentary muscle fatigue within the anaerobic energy system parameters.

Based on the results of these (3,8) and other studies (2,5,6) it would appear that you may receive similar strength building stimulus from various resistance training protocols that produce muscle fatigue within the anaerobic energy system. While some individuals (e.g., those with mostly fast-twitch or slow-twitch muscle fibers) may respond better to lower or higher repetition training, most of us should attain about the same strength gains training with a range of repetitions (e.g., 5 to 15 reps per set).

Repetition Ranges For Children
Because children are not simply small adults, we also studied their physiological response to lower and higher repetition resistance training (4). This study involved 43 boys and girls (mean age 8 years) who trained with one set of 6 to 8 repetitions or one set of 13 to 15 repetitions, or served as controls (non-training subjects). The strength training groups performed one set of each resistance exercise, twice a week for a period of 8 weeks, using the following youth-sized weightstack machines: leg extension, leg curl, leg press, hip abduction, pullover, chest press, seated row, abdominal curl and pulldown. Unlike our adult studies, the youth who trained with moderate weightloads and more repetitions (13 to 15 reps) gained 28 percent more strength whereas those who trained with heavier weightloads and fewer repetitions (6 to 8 reps) gained 18 percent more strength.

We therefore recommend that preadolescents typically train with higher repetition ranges (e.g., 10 to 15 reps/set), as this protocol appears to be more productive for strength development and more conservative with respect to injury prevention.

Summary
Genetics generally determines whether you have low muscle endurance (more fast-twitch fibers), high muscle endurance (more slow-twitch fibers), or moderate endurance muscles (even mix of fast-twitch and slow-twitch fibers). Moderate endurance muscles respond well to a fairly wide range of repetitions (e.g., 5 to 15 reps), low endurance muscles respond better to fewer repetitions (e.g., 3 to 7 reps), and high endurance muscles respond better to higher repetitions (e.g., 13 to 17 reps).

Most adults have moderate endurance muscles that increase strength equally well from 5 to 15 repetition training, as long as they experience temporary muscle fatigue within the anaerobic energy system (approximately 20 to 90 seconds). One study found no differences in strength development from 4-repetition training and 10-repetition training, and another study showed similar strength gains from 7-repetition training and 14-repetition training.

Research indicates that children, unlike adults, respond more favorably to higher repetition training (13 to 15 reps) than to lower repetition training (6 to 8 reps).

References

1. American College of Sports Medicine. 1998. The recommended quantity and
   quality of exercise for developing and maintaining cardio respiratory and muscular
   fitness in healthy adults. Medicine and Science in Sports and Exercise 30: 975-999.

2. Bemben, D., N. Fetters, M. Bemben, N. Nabavi, and E. Koh. 2000. Musculoskeletal responses to high and low intensity resistance training in early postmenopausal women. Medicine and Science in Sports and Exercise 32 (11): 1949-1957.
3. Chestnut, J. and D. Docherty. 1999. The effects of 4 and 10 repetition maximum
   weight training protocols on neuromuscular adaptations in untrained men. Journal of Strength and Conditioning Research 13: 353-359.

4. Faigenbaum, A., W. Westcott, and R. LaRosa Loud. 1999. The effects of different
   resistance training protocols on muscular strength and endurance development in
   children. Pediatrics 104: 1-7.

5. Kerr, D., A. Morton, I. Dick, and R. Prince. 1996. Exercise effects on bone mass
   in postmenopausal women are site-specific and load-dependent. Journal of Bone and Mineral Research 11 (2): 218-225.

6. Vincent, K. and R. Braith. 2002 Resistance exercise and bone turnover in elderly
   men and women. Medicine and Science in Sports and Exercise. 34 (1): 17-23.

7. Westcott, W. 1993. How many repetitions? Nautilus2 (3) 6-7.
8. Westcott, W., and R. LaRosa Loud. 2000. Research on repetition ranges. Master Trainer 10 (4): 16-18.

Effective fitness instructors come in various shapes and sizes, but they tend to have a few characteristics in common. For example, good teachers typically provide concise exercise explanations and precise exercise demonstrations to help participants clearly understand the desired physical performance (1, 2, 3). In simplest terms, they have mastered the art of show and tell, and use their communication skills to educate and motivate their clients.

Another factor that influences participant behavior is positive reinforcement. Positive reinforcement may take many forms, including a smile, a pat on the back, a sincerely stated “good job”, or acknowledgement of attaining a predetermined goal.

A related teaching technique is referred to as performance feedback, which requires specific instructor comments on the clients exercise execution. Checking a participant’s heart rate, counting out leg press repetitions, saying, “your movement range is a little short,” “your repetition speed is just right,” and “your breathing pattern is perfect” are all examples of instructor feedback. Basically, the purpose of feedback is to tell clients what they are doing correctly or incorrectly with respect to posture, technique and other aspects of their exercise performance.

Taken together, these teaching behaviors (exercise explanations, exercise demonstrations, positive reinforcement, performance feedback) indicate a certain level of exercise focus. Instructors who give frequent exercise explanations, exercise demonstrations, positive reinforcement and performance feedback provide a high-focus exercise environment, whereas instructors who perform these behaviors infrequently provide a low-focus exercise environment. Research has been unclear as to whether high amounts of (often repetitive) feedback or low amounts of (often very specific) feedback are more beneficial to participants’ physiological progress and/or exercise maintenance.

Experimental Research
Within the context of a more comprehensive research project, we recently studied the effects of high-focus and low-focus exercise environments on strength training performance in beginning adult exercisers. The study subjects were 71 men and women (27 to 84 years of age) who completed a 10-week strength training program for previously sedentary adults. All subjects completed detailed medical history questionnaires prior to acceptance in the research program. Each participant was carefully assessed (Microfit computerized fitness analysis) in a private testing room before and after the 10-week training period for the following fitness parameters: (1) bodyweight; (2) body composition; (3) resting blood pressure; (4) muscle strength; (5) and joint flexibility. Data was analyzed for significant within-group and between-group differences.

All of the subjects trained in small classes (3 to 6 participants), under close supervision (1 or 2 instructors), two or three days per week (Tuesdays and Thursdays or Mondays, Wednesdays and Fridays), in a private exercise room. All of the classes were one hour in length, during which the participants performed 12 resistance exercises for their major muscle groups and did approximately 20 minutes of moderate effort aerobic activity (treadmill walking or recumbent cycling).

The strength training program consisted of the following exercises performed on standard weightstack machines: (1) leg extension; (2) seated leg curl; (3) chest cross; (4) chest press; (5) pullover; (6) lateral raise; (7) biceps curl; (8) triceps extension; (9) low back extension; (10) abdominal curl; (11) neck flexion; and (12) neck extension. Each exercise was performed for one set with a resistance that permitted 8 to 12 controlled (6-second) repetitions. Whenever 12 repetitions were completed with proper form the weightload was increased by about 5 percent (typically 2.5 pounds).

Each participant in the a.m. classes trained under conditions of high exercise focus (frequent instructor interactions related to exercise performance), whereas subjects in the p.m. classes trained under conditions of low exercise focus (frequent instructor interactions on topics unrelated to exercise performance). The p.m. program participants experienced the same initial exercise instruction as the a.m. classes during the first 2 weeks of training. However, the p.m. instructors provided minimal amounts of exercise- focused information during the following 8 weeks (just enough to ensure proper training technique and progression). Although they interacted frequently with class members, the conversations were typically on topics other than exercise performance.

Research Results
Of the 81 subjects who began this study, 5 dropped out of the a.m. classes (high-focus group) and 5 dropped out of the p.m. classes (low-focus group), leaving 71 participants who completed the 10-week training program. The training compliance rate (percentage of exercise sessions attended) was 85 percent for both treatment groups. The 45 subjects in the a.m. classes were about 80 percent female (mean age 59.7 years), and the 26 subjects in the p.m. classes were about 90 percent female (mean age 55.5 years). The high-focus group (a.m. classes) made significant improvements in percent fat, fat weight, lean weight, muscle strength, joint flexibility and diastolic blood pressure, whereas the low-focus group (p.m. classes) attained significant improvements in percent fat, fat weight, lean weight and joint flexibility. As shown in table 1, the high-focus group achieved significantly greater improvements than the low-focus group in percent fat
(-2.7% vs -1.7%) lean weight (+4.0 lbs. vs +2.2 lbs.), muscle strength (+9.0 lbs vs. +2.4 lbs) and diastolic blood pressure (-8.0 mmHg vs +1.5 mmHg).

Discussion
Based on these findings it would appear that strength training under conditions of high exercise focus may produce more physiological improvements (e.g., percent fat, lean weight, muscle strength, diastolic blood pressure) than strength training under conditions of low exercise focus. In this study, higher levels of exercise focus were associated with faster rates of physical fitness attainment, whereas lower levels of exercise focus were associated with slower rates of physical fitness attainment.

It would therefore seem obvious that fitness instructors should provide high levels of exercise focus, and this is true if participants’ physiological improvement is the top priority. However, psychological data from another aspect of this study offer a different perspective (6). Subjects who received low levels of exercise focus experienced significantly greater increases in revitalization and significantly greater decreases in feelings of physical exhaustion immediately after their strength training sessions. Such after-exercise changes on these feeling states have been associated with long-term exercise adherence (4, 5). Also, only the low-focus group had significant reductions in depression and tension over the course of the 10-week strength training program. These are important considerations with respect to emotional wellness and exercise adherence, especially for previously sedentary adults who need to establish an exercise habit for ongoing wellness.

It may be that high levels of exercise focus challenge new participants in a way that increases their training effectiveness but decreases their training enjoyment. Whereas highly motivated athletes may want as much exercise focus as possible, new exercisers may feel more comfortable with infrequent exercise-related interactions.

While more research needs to be conducted on this topic, we suggest that fitness instructors provide new exercise participants with moderate exercise focus. For example, two or three pertinent and positive feedback statements per training session may be sufficient to enhance clients’ exercise effectiveness without altering the psychological benefits associated with self-directed physical activity.

We further recommend that the majority of focused instructor interactions address the major aspects of proper exercise performance, without being too technical during the first few weeks of training. We also believe that better results may be attained from exercise-focused comments that reinforce the participants’ training efforts. Finally, we believe focused statements that do not disrupt the clients’ exercise flow are probably more effective from both a physiological and psychological perspective.

Because clients are individuals, some may respond positively to high-focus exercise environments and others may not. Be sensitive to each exerciser’s response to the teaching technique and do your best to instruct accordingly.

References

1. Annesi, J. (1999). Evaluating ability to support client adherence. Fitness
   Management, 15(11), 36-38, 41. Also available: http://www.fitnessworld.com.

2. Annesi, J.J. (1999). Relationship between exercise professionals’ behavioral
   styles and clients’ adherence to exercise. Perceptual and Motor Skills,
   89, 597-604.

3. Annesi, J. (2000). Hiring trainers who motivate clients. IDEA Fitness
   Manager, 12(1), 5-7.

4. Annesi, J.J. (2002). Relationship between changes in acute exercise-induced
   feeling states, self-motivation, and adults’ adherence to moderate
   aerobic exercise. Perceptual and Motor Skills, 94, 425-439.

5. Annesi, J.J. (2002). Self-motivation moderates effect of exercise-induced
   feelings on adherence. Perceptual and Motor Skills, 94, 467-475.

6. Annesi, J.J., Westcott, W.L., Loud, R.L., & Powers, L. (2002). Effects of
   association and dissociation formats on resistance exercise-induced
   emotion change and physical self-concept in older women. Manuscript
   submitted for publication.

Table 1. Mean pre-training and post-training fitness scores for high exercise focus and

low exercise focus groups (71 subjects).
______________________________________________________________________________
Association Group Dissociation Group
Variable Pre Post Change Pre Post Change
______________________________________________________________________________
Bodyweight (lbs) 180.0 178.9 -1.1 197.0 196.1 -0.9

Percent Fat (%) 30.4 27.7 -2.7 *E 31.7 30.0 -1.7 *

Fat Weight (lbs) 56.1 50.9 -5.2 * 64.9 61.6 -3.3 *

Lean Weight (lbs) 123.8 127.8 +4.0 *E 132.2 134.4 +2.2 *

Strength (lbs) 46.0 55.0 +9.0 *E 48.2 50.6 +2.4 *

Flexibility (in) 30.1 33.4 +3.3 * 38.2 40.6 +2.4 *

Systolic BP (mmHg) 136.3 130.9 -5.4 130.4 127.7 -2.7

Dias. BP (mmHg) 76.5 68.5 -8.0 *E 73.1 74.6 +1.5
______________________________________________________________________________

* significant within-group change (p <0.05)

E significant between-group difference (p <0.05)

As you are undoubtedly aware, our nation is presently experiencing an epidemic of childhood obesity. Unfortunately, for every youth who is overfat, there are at least two who are underfit. With less emphasis on physical education, and even the elimination of recess in elementary schools, this sad situation is becoming progressively more prevalent.

Overweight children typically become overweight adults, and overweight adults have significantly higher risk of serious degenerative diseases, including high blood pressure, heart problems, stroke, diabetes, several types of cancer, low back pain, and arthritis. Even worse, many children already have beginning stages of cardiovascular disease. Likewise, osteoporosis is actually a childhood problem (insufficient bone development) that manifests itself in the adult years.

In addition to the medical concerns associated with childhood obesity, there are many related physiological problems. Overweight youth usually score poorly on fitness tests such as timed runs, vertical jumps, long jumps, push-ups, pull-ups, sit-ups and agility assessments. They generally don’t do well in endurance activities such as soccer, or in jumping activities such as basketball. They don’t even like to play tag because they are always “it.”

Psychologically, research shows that obese children score very low in self-image and self-confidence. They seldom play sports, organized or otherwise, and are less involved socially than their more fit peers. One recent study sadly revealed that children who are obese and children who suffer from cancer have similar outlooks on life.

One thing we know for sure, the old adage that kids will eventually outgrow their weight problem is seldom true in today’s sedentary society. With little activity time at school or at home, obese youth need all the help we can give them to enjoy the benefits of effective exercise. Of course, any exercise is better than no exercise, but for best results the exercise program should match the physical characteristics of children.

Youth, especially elementary school-aged children, have a distinctly different physiological pattern for performing physical activity. They exercise all-out for 30 to 60 seconds, then they rest. After a minute or two of recovery, they exercise all-out again for 30 to 60 seconds. They basically have an innate ability to exercise in an interval-training manner. Conversely, most young people do not fit the adult exercise model of a 5-minute warm-up, 30 minutes of continuous cycling or jogging, followed by a 5-minute cool-down.

One important physical activity that matches children’s physiological factors is strength exercise. They perform a 30 to 60 second set of strength exercise, rest a minute or two, then perform another set of strength exercise. In addition, heavier kids typically lift more weight than their lighter peers, making this one of the few activities in which overweight children experience success.

Another benefit of youth strength training is improved body composition. Unlike other forms of exercise, strength training builds muscle and bone resulting in a stronger musculoskeletal system and greater functional capacity. You may have heard that strength training is detrimental to muscle and bone development in children, but nothing could be farther from the truth. To the contrary, a recent nine-month study with nine year old girls showed four times as much bone mineral density increase in girls who performed strength exercise compared to those who did other types of physical activity (6.2% vs. 1.4% increased BMD). In fact, every research study published on youth strength training has shown positive results, with no reports of injury or developmental delay.

Of course, the youth strength training research programs are highly supervised, and this is indeed the key to safe and successful exercise experiences. For example, the South Shore YMCA in Massachusetts has run multiple strength training programs for children (ages 7 through 11) and young teens (ages 12 through 14) for the past 19 years with no injuries and very few dropouts. In fact, the attendance rate has consistently exceeded 90 percent, indicating that boys and girls respond favorably to well-conducted programs of strength exercise.

While some facilities have the advantage of using youth-sized strength training machines, children can attain excellent results with other types of resistance equipment including free-weights, elastic bands, medicine balls and Bow-Flex devices. Careful supervision, gradual progression and proper technique are the critical training components for children.

With respect to exercise progression, boys and girls should use a resistance that they can lift between 10 and 15 repetitions. When they complete 15 repetitions, the resistance should be increased by approximately five percent.

Proper training technique includes good posture, slow exercise speed, and full exercise range, as well as continuous breathing on every repetition. Fast reps, short reps, breathholding and squirming actions should be avoided.

Like adults, children should train all of their major muscle groups. Fortunately, this can be accomplished with about seven basic exercises. If appropriate weight stack machines are available, consider the following sequence of youth strength training exercises: (1) leg press for the front thigh, rear thigh and hip muscles; (2) chest press for the chest and rear arm muscles; (3) seated row for the upper back and front arm muscles; (4) shoulder press for the shoulder and rear arm muscles; (5) pull down for the mid back and front arm muscles; (6) trunk flexion for the midsection muscles; and (7) trunk extension for the lower back muscles. If dumbbells are used, the following exercise sequence is recommended: (1) dumbbell squat for the front thigh, rear thigh and hip muscles; (2) dumbbell bench press for the chest and rear arm muscles; (3) dumbbell row for the upper back and front arm muscles; (4) dumbbell press for the shoulder and rear arm muscles; (5) dumbbell curl for the front arm muscles; (6) bodyweight trunk curls for the midsection muscles; and (7) bodyweight trunk extensions for the lower back muscles.

Although one strength training session per week is sufficient, our research shows better results with two non-consecutive strength workouts on a weekly basis. Overweight boys and girls who do strength exercise in this manner average 2.5 pounds more lean (muscle) tissue and 3.0 pounds less fat every eight weeks of training.

Finally, most youth (overweight or otherwise) like strength training. However, they seem to like it even better when it is part of an overall physical activity program that includes lots of large muscle exercise such as low-organized games, relays, ball-handling skills, dynamic stretching and equipment utilization (hoops, medicine balls, wands, ropes, beanbags, etc.). One well-researched approach is to sandwich 20 minutes of sensible strength training between 15 minutes of game-like warmup activities and 15 minutes of similar but less vigorous cooldown activities. This provides a well-rounded program of muscular and cardiovascular exercise that is physiologically beneficial and psychologically interesting.

For further information or article reprints on youth strength training call Wayne Westcott at (617) 479-8500 ext. 140.

Summary
The main purpose of this study was to examine the effect of training intensity on muscle deoxygenation, which may be an indicator of muscle tissue damage that is thought to be essential for increases in muscle size (hypertrophy) and strength. Eleven male athletes experienced in strength training performed four sets of barbell squats using either a lower-intensity and higher volume protocol (15 repetitions with 60 percent of their maximum weightload) or a higher-intensity and lower volume protocol (4 repetitions with 90 percent of their maximum weightload). The results showed no apparent difference in muscle deoxygenation between the lower-intensity (15 repetitions) exercise protocol and the higher-intensity (4 repetitions) exercise protocol. However, time-dependent postexercise reoxygenation was significantly longer in the lower intensity (15 repetitions) training protocol. Both testosterone and growth hormone concentrations were elevated immediately after the exercise sessions, and at 20 minutes and 40 minutes post exercise. Although there were no differnces in testosterone levels, growth hormone was significantly higher at 20 and 40 minutes post exercise for the lower intensity (15 repetitions) training protocol.

Implications
Training to muscle fatigue with a heavier weightload (90 percent maximum) and fewer repetitions (4 reps) produced similar effects on muscle deoxygenation as training to muscle fatigue with a lighter weightload (60 percent maximum) and more repetitions (15 reps). However, the longer set of resistance exercise did require a longer time for muscle reoxygenation, and produced higher growth hormone concentrations during the post exercise period.

Citation
Hoffman, J. J. Im, K. Rundell, J. Kang, S. Nioka, B. Speiring, R. Kime, and B. Chance. Effects of muscle oxygenation during resistance exercise on anabolic hormone response. Medicine and Science in Sports and Exercise, 35 (11): 1929-1934, 2003.

Summary
This study compared the effects of two strength training modalities (free-weights and a unique interim elastomer resistive device used on the International Space Station), and two exercise protocols (3 sets of 6 to 12 repetitions each and 6 sets of 6 to 12 repetitions each) on muscle strength, muscle volume, lean body mass, and bone mineral density. Twenty-eight untrained males were assigned to one of the following exercise groups: (1) control; (2) 3 sets of free-weights; (3) 3 sets of elastomer device; (4) 6 sets of elastomer device; and trained 3 days a week for 16 weeks. Results showed similar increases in muscle strength and muscle volume for all three groups that performed resistance exercise. However, only the free-weight group experienced significant increases in lean body mass and bone mineral density. Doubling the training volume (6 sets vs. 3 sets) did not produce any additional improvement in any of the training responses.

Implications
Although the softer resistance supplied by the elastomer device produced similar muscle strength and muscle volume increases to the harder resistance supplied by the free weights, only the latter training modality resulted in greater lean body mass and bone mineral density. Doubling the number of exercise sets did not elicit any further training benefits, but may have contributed to overtraining injuries that occurred in half of the 6-set subjects.

Citation
Schneider, S., W. Amonette, K. Blazine, J. Bentley, S. Lee, J. Loehr, A. Moore, M. Rapley, E. Mulder, and S. Smith. Training with the international space station interim resistive exercise device. Medicine and Science in Sports and Exercise, 35 (11): 1935-1945, 2003.