Ogasawara, R., Yasuda, T., Sakamaki, M., Ozaki, H., & Abe, T. (June 2, 2010). Six weeks resistance training and retraining induced muscle hypertrophy and strength gains in young men. Presentation 1500 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

This study investigated the effects of high-intensity resistance training and retraining following a short-term detraining period on muscle size and strength. Previously untrained young men (N = 14) were divided into two training groups: continuous training (N = 7) or training/detraining (N = 7). Ss participated in high-intensity bench press exercise training (75% 1 RM), three days per week for 15 weeks. The continuous training group performed continuously over the 15 weeks while the training/detraining group had a three week detraining period between weeks 7 and 9. MRI-measured triceps and pectorals major muscle cross-sectional area and maximal dynamic (bench press 1 RM) and isometric (elbow extension) maximal voluntary contraction strength were measured before the commencement of training and at the end of weeks 6, 9, and 15.

After the initial six weeks of training, increases in bench press 1 RM, elbow extension maximal voluntary contraction and triceps and pectorals major muscle cross-sectional area were similar between the continuous training and training/detraining groups. During the three weeks of detraining, however, muscle cross-sectional area decreased but strength was maintained in the training/detraining group while muscle size and strength continued to increase for the continuous training group. In the training/detraining group, the increases in strength and muscle cross-sectional area were similar between the initial six weeks training and the six weeks of retraining. On the other hand, training adaptation during the final six weeks for the continuous training group was significantly lower compared with the initial six weeks of training. As a result, improvements in muscle cross-sectional area and strength were similar between the continuous training and training/detraining groups by the end of the study.

Implication. A short-term detraining period does not inhibit muscle adaptations when compared to continuous training programs.

This study verifies a number of phenomena associated with resistance training that are often ignored or contradicted by strength-training specialists.

• Gains from resistance training occur quite quickly (e.g., within two months) and then taper off. That leads one to question why sport teams continue with exhausting resistance training for full seasons when the gains diminish markedly after a relatively short time. Persistent strength training after major gains have been made would yield no demonstrable benefit for the general fitness of the athlete and only have to potential to be harmful, particularly through injury caused by the resistance exercises.
• When resistance training is interrupted, for example through injury, strength is not lost or if it is it occurs at a very slow rate [strength gains are retained in the absence of further training]. When strength training starts again after an absence, gains that would have been developed through continuous training are soon made up with the athlete not deriving any disadvantage from the period of inactivity. Coaches and athletes should not worry about missing a resistance-training session.
• For many sports, increases in muscle cross-sectional area and concomitant body weight could be detrimental to sport performance (e.g., swimmers would sink lower in the water increasing resistive drag; cyclists and runners would have to propel more weight by generating greater propulsive forces).

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