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Strength in Numbers

American Fitness, March, 2001

According to findings published by ACSM, Ball State University study shows supervised strength training yields maximum results.

Exercise enthusiasts, new and experienced, often wonder if a personal trainer or exercise supervisor can help them get fit faster. The American College of Sports Medicine (ACSM) recently published a study in its official monthly journal, Medicine & Science in Sports & Exercise[R] (MSSE[R]), that addressed this question specifically for fitness performance related to weight training.

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Building on previous research that hinted at a relationship between fitness improvement and supervised training, the team of researchers, led by Scott A. Mazzetti of Ball State University in Muncie, Indiana, decided to attack the problem directly. "Too many variables made it impossible to accurately correlate strength improvement with supervision," said Mazzetti. "We thought one-to-one supervision would make a pronounced difference, so we designed a test to compare the changes of maximal strength in supervised vs. unsupervised resistance training."

Twenty men ages 18 to 35 were given training logs for the 12-week test. All had a year or two of experience in resistance training, but none had ever worked with a personal trainer. Each participant had his body fat measured and was tested for squat and bench press performance, jump squat power and bench press endurance. Every participant used the same facility and training equipment and, in accordance, training was identical for both groups so that the learning curve would not affect the results.

The directly supervised group was trained one-on-one by an ACSM-certified Health/Fitness Instructor[TM] (HFI), who served as personal trainer for all sessions and maintained their logs. The unsupervised group attended only one session with the HFI and kept their own logs. Training loads were increased progressively, using repetition maximum zones. While the HFI selected the increments for the participants in the supervised training group, the unsupervised participants selected their own, based on the same principles. Also, the HFI provided spotting and advice to the supervised group, whereas the unsupervised men relied on self-motivation.

In the beginning of the study, there were no differences between the two groups and significant strength gains were achieved by both groups after the training period. However, body mass, fat mass and fat-free mass were significantly affected only in the supervised group. Most importantly, not only did the supervised group show a significantly greater increase in strength in major muscle groups, it occurred more rapidly than in the non-supervised group. In fact, the men in the supervised group showed a 30 percent to 45 percent higher improvement in maximal strength indices than the unsupervised group. Moreover, the supervised group reached that peak approximately 30 percent faster than their unsupervised counterparts.

The researchers noted that use and toleration of greater training loads--promoted by the HFI--may have elicited enough of a training stimulus to explain the differences in fitness results between the two groups. Another potential explanation noted by the authors includes the differing effects of supervision on such psychological factors as competitiveness and external motivation.

Although the results of the study suggest that the assistance of an exercise supervisor or trainer can help maximize fitness results from a heavy resistance training protocol, the unsupervised group significantly improved its strength levels as well. Thus, existing guidelines for muscular strength and endurance (such as those in the ACSM Position Stand, The Recommended Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness and Flexibility in Healthy Adults,[C]1998), which can be accomplished without supervision, continue to be relevant for individuals interested in muscular fitness corresponding to health and quality of life.

For More Information

Medicine & Science in Sports & Exercise[R] is the official journal of the American College of Sports Medicine, and is available from Lippincott, Williams & Wilkins at 1-800-638-6423. For a complete copy of the research paper (Vol. 32, No. 6, p. 1175) or to speak with a leading sports medicine expert on the topic, contact the Public Information Department at 317-637-9200. Visit ACSM online at www.acsm.org.

The conclusions outlined here are those of the researchers only, and should not be construed as an official statement of either the American College of Sports Medicine (ACSM) or the Aerobics and Fitness Association of America (AFAA).

Strength in Numbers

American Fitness, March, 2001

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