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Strength Training: Rationale for Current Guidelines for Adult Fitness Programs
Matthew S. Feigenbaum, Med; Michael L. Pollock, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 2 - FEBRUARY 97
Frequency of Training
The frequency of training for a muscle group is also an important component of a strength training program design (18,29,30,34). The rest period must allow for muscle recuperation and development and prevent overtraining. However, too much rest between training sessions can result in detraining. A 48-hour rest between concurrent training sessions is generally recommended (18), which corresponds with a 3-days/wk frequency of training for individual muscle groups. Although 3 days/wk of strength exercise is generally recommended for maximal strength gains, the literature does not always support this. Research indicates that isolated muscle groups are unique in their trainability and adaptability to strength training (18,30,35). Table 3 (not shown) summarizes the results from strength training studies comparing frequency of training using a variety of muscle groups.
Several studies (34,36,37) evaluating the effects of frequency of training have shown that four or more training sessions per week produced optimal strength gains in several muscle groups. Using the standard bench press exercise, Gillam (34) indicated that training 5 days/wk over a 7-week period was superior to 1, 2, 3, or 4 days/wk training regimens. Interestingly, training 3 or 4 days/wk produced similar results, which were significantly greater than those obtained by the groups training 1 or 2 days/wk. Hunter (37) and Henderson (36) also found that increasing the frequency of bench press training to 4 and 3 days/wk, respectively, produced greater strength gains than lesser-frequency protocols. In contrast, Berger (38) found that bench pressing either 2 or 3 days/wk produced similar strength gains over the course of 12 weeks. Similar findings have also been reported for studies evaluating strength gains in the lower limb muscles. Braith et al (29) found 3 days/wk to be superior to 2 days/wk in increasing quadriceps (knee extension) strength, and an earlier study by Barham (39) showed that performing the squat exercise 3 days/wk was as effective as 5 days/wk, and that both training frequencies were superior to squatting 2 days/wk.
While the chest, arms, and legs may require a training frequency of 3 days/wk or more to develop optimal strength gains, additional studies suggest that the muscles supporting the spine (eg, lumbar extensors) and smaller muscles of the torso may respond maximally with fewer training sessions per week. For example, Graves et al (30) found no significant differences in dynamic and isometric strength generated by isolated lumbar extensor muscles among groups training 1, 2, or 3 days/wk for 20 weeks. In a follow-up study (40), it was demonstrated that these maximal strength gains could then be maintained for up to 12 weeks when training frequency was reduced to one training session every 2 to 4 weeks. When assessing cervical rotation strength, Leggett et al (31) and DeFilippo (41) found that training frequencies of 2 and 3 days/wk were superior to 1 day/wk or 1 day/2 wks over a 12-week training period. Pollock et al (24) indicated that training 2 days/wk is superior to 1 day/wk for increasing cervical extension strength, but because training 3 days/wk was not evaluated, no inferences can be made in this regard. As for the muscles involved in torso rotation, DeMichele et al (35) concluded that the 2 days/wk training frequency obtained better adherence and equal strength gains compared with 3 days/wk, and that both 2 and 3 days/wk programs were superior to 1 day/wk.
Based on the findings of these studies, it is clear that there is no single optimal frequency of strength training for all muscle groups. Whether the differences in the time course of strength gains occurring in isolated muscle groups are due to variations in neural integration, muscle morphology, autoregulation, or other mechanisms warrants further investigation. Although clinicians must consider the specific needs of individual patients, particularly those whose orthopedic limitations may improve or be aggravated by adjusting the frequency of training, the current guidelines seem appropriate: a minimum of 2 or 2 to 3 days/wk (table 1). When prescribing traditional strength exercise programs for beginners (8 to 10 exercises, emphasizing the major muscle groups), a minimum of 2 days per week training frequency is recommended over more frequent training sessions because it allows time for recuperation, is less time-consuming, improves compliance (2,17), and produces most of the health and fitness benefits in the untrained person.
Matthew S. Feigenbaum, Med; Michael L. Pollock, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 25 - NO. 2 - FEBRUARY 97
Frequency of Training
The frequency of training for a muscle group is also an important component of a strength training program design (18,29,30,34). The rest period must allow for muscle recuperation and development and prevent overtraining. However, too much rest between training sessions can result in detraining. A 48-hour rest between concurrent training sessions is generally recommended (18), which corresponds with a 3-days/wk frequency of training for individual muscle groups. Although 3 days/wk of strength exercise is generally recommended for maximal strength gains, the literature does not always support this. Research indicates that isolated muscle groups are unique in their trainability and adaptability to strength training (18,30,35). Table 3 (not shown) summarizes the results from strength training studies comparing frequency of training using a variety of muscle groups.
Several studies (34,36,37) evaluating the effects of frequency of training have shown that four or more training sessions per week produced optimal strength gains in several muscle groups. Using the standard bench press exercise, Gillam (34) indicated that training 5 days/wk over a 7-week period was superior to 1, 2, 3, or 4 days/wk training regimens. Interestingly, training 3 or 4 days/wk produced similar results, which were significantly greater than those obtained by the groups training 1 or 2 days/wk. Hunter (37) and Henderson (36) also found that increasing the frequency of bench press training to 4 and 3 days/wk, respectively, produced greater strength gains than lesser-frequency protocols. In contrast, Berger (38) found that bench pressing either 2 or 3 days/wk produced similar strength gains over the course of 12 weeks. Similar findings have also been reported for studies evaluating strength gains in the lower limb muscles. Braith et al (29) found 3 days/wk to be superior to 2 days/wk in increasing quadriceps (knee extension) strength, and an earlier study by Barham (39) showed that performing the squat exercise 3 days/wk was as effective as 5 days/wk, and that both training frequencies were superior to squatting 2 days/wk.
While the chest, arms, and legs may require a training frequency of 3 days/wk or more to develop optimal strength gains, additional studies suggest that the muscles supporting the spine (eg, lumbar extensors) and smaller muscles of the torso may respond maximally with fewer training sessions per week. For example, Graves et al (30) found no significant differences in dynamic and isometric strength generated by isolated lumbar extensor muscles among groups training 1, 2, or 3 days/wk for 20 weeks. In a follow-up study (40), it was demonstrated that these maximal strength gains could then be maintained for up to 12 weeks when training frequency was reduced to one training session every 2 to 4 weeks. When assessing cervical rotation strength, Leggett et al (31) and DeFilippo (41) found that training frequencies of 2 and 3 days/wk were superior to 1 day/wk or 1 day/2 wks over a 12-week training period. Pollock et al (24) indicated that training 2 days/wk is superior to 1 day/wk for increasing cervical extension strength, but because training 3 days/wk was not evaluated, no inferences can be made in this regard. As for the muscles involved in torso rotation, DeMichele et al (35) concluded that the 2 days/wk training frequency obtained better adherence and equal strength gains compared with 3 days/wk, and that both 2 and 3 days/wk programs were superior to 1 day/wk.
Based on the findings of these studies, it is clear that there is no single optimal frequency of strength training for all muscle groups. Whether the differences in the time course of strength gains occurring in isolated muscle groups are due to variations in neural integration, muscle morphology, autoregulation, or other mechanisms warrants further investigation. Although clinicians must consider the specific needs of individual patients, particularly those whose orthopedic limitations may improve or be aggravated by adjusting the frequency of training, the current guidelines seem appropriate: a minimum of 2 or 2 to 3 days/wk (table 1). When prescribing traditional strength exercise programs for beginners (8 to 10 exercises, emphasizing the major muscle groups), a minimum of 2 days per week training frequency is recommended over more frequent training sessions because it allows time for recuperation, is less time-consuming, improves compliance (2,17), and produces most of the health and fitness benefits in the untrained person.
