Comparison of muscle hypertrophy following 6-month of continuous and periodic strength training

Abstract

To compare the effects of a periodic resistance training (PTR) program with those of a continuous resistance training (CTR) program on muscle size and function, 14 young men were randomly divided into a CTR group and a PTR group. Both groups performed high-intensity bench press exercise training [75 % of one repetition maximum (1-RM); 3 sets of 10 reps] for 3 days per week. The CTR group trained continuously over a 24-week period, whereas the PTR group performed three cycles of 6-week training (or retraining), with 3-week detraining periods between training cycles. After an initial 6 weeks of training, increases in cross-sectional area (CSA) of the triceps brachii and pectoralis major muscles and maximum isometric voluntary contraction of the elbow extensors and 1-RM were similar between the two groups. In the CTR group, muscle CSA and strength gradually increased during the initial 6 weeks of training. However, the rate of increase in muscle CSA and 1-RM decreased gradually after that. In the PTR group, increase in muscle CSA and strength during the first 3-week detraining/6-week retraining cycle were similar to that in the CTR group during the corresponding period. However, increase in muscle CSA and strength during the second 3-week detraining/6-week retraining cycle were significantly higher in the PTR group than in the CTR group. Thus, overall improvements in muscle CSA and strength were similar between the groups. The results indicate that 3-week detraining/6-week retraining cycles result in muscle hypertrophy similar to that occurring with continuous resistance training after 24 weeks.

The order of concurrent endurance and resistance exercise modifies mTOR signaling and protein synthesis in rat skeletal muscle

“…The well-known adaptive features of chronic muscle contraction include muscle hypertrophy and increased strength. These features are induced by high-intensity muscle contraction, such as that involved in resistance exercises (RE) (50,52). Other typical adaptations are increases in oxidative capacity and glucose uptake, which are induced by low-intensity, highvolume muscle contraction, such as that observed during endurance exercises (EE) (5,28,53).…”

mTOR signaling response to resistance exercise is altered by chronic resistance training and detraining in skeletal muscle

“…In humans, resistance training-induced muscle anabolism and subsequent hypertrophy occur most rapidly during the early phases of training, becoming progressively slower with time (33,40). On the other hand, following a detraining period, muscle adaptation responses may return to their initial levels, and the effects of retraining on muscle growth are similar to those observed during the initial phase of resistance training (33,37). However, the mechanisms underlying such changes in the sensitivity of muscles to training stimuli are unclear.…”

Periodization for optimizing strength and hypertrophy; the forgotten variables

“…It should be noted that, though there were differences between the continuous and non-continuous groups in slope of improvements at different time points in the aforementioned studies, [17][18][19][20] it is naïve to assume that the rate of improvement over these short periods is in anyway indicative of what the slopes of improvement may look like over a longer period of time. The simple fact of the matter is that we do not know the degree to which the continued manipulation in any RT variable over extended periods of time might affect slope of change for any outcome variable.…”

“…Both CTR and RTR groups showed similar increases in both strength (bench press 1RM) and muscle size of the triceps brachii (TB) and pectoralis major (PM) following the 15-week intervention. In a later study Ogasawara, et al 19 repeated a similar research design across 24 weeks. The CTR group trained continuously for 24 weeks (3 sets of 10 repetitions @ 75% 1RM, 3 days per week), whilst the periodic re-training (RTR) group performed 3 cycles of 6 weeks of RT, with 3-week detraining periods between training cycles.…”

“…It is noteworthy that none of this research considering detraining periods [18][19][20] was included in the meta-analysis by Williams, et al 3 or discussed the systematic review by Grgic, et al…”