Cycle training induces muscle hypertrophy and strength gain: strategies and mechanisms

Abstract

Cycle training is widely performed as a major part of any exercise program seeking to improve aerobic capacity and cardiovascular health. However, the effect of cycle training on muscle size and strength gain still requires further insight, even though it is known that professional cyclists display larger muscle size compared to controls. Therefore, the purpose of this review is to discuss the effects of cycle training on muscle size and strength of the lower extremity and the possible mechanisms for increasing muscle size with cycle training. It is plausible that cycle training requires a longer period to significantly increase muscle size compared to typical resistance training due to a much slower hypertrophy rate. Cycle training induces muscle hypertrophy similarly between young and older age groups, while strength gain seems to favor older adults, which suggests that the probability for improving in muscle quality appears to be higher in older adults compared to young adults. For young adults, higher-intensity intermittent cycling may be required to achieve strength gains. It also appears that muscle hypertrophy induced by cycle training results from the positive changes in muscle protein net balance.Keywords: aerobic exercise, muscular adaptation, lower body, cycling, ergometer Endurance training is a major part of any exercise program seeking to improve aerobic capacity and cardiovascular health. Another major part of exercise programming is strength/ resistance training, which improves muscle morphology. Thus to improve muscular strength and cardiovascular fitness in young, middle-aged and older populations, the American College of Sports Medicine recommends combining training intensity, volume, and frequency to optimize muscle hypertrophy and strength gain as well as aerobic capacity (V O 2 max) (23). However, the vigorous training intensity and/or high training frequency might hinder some older adults from participating in this type of training program. Interestingly, recent studies have reported concurrent improvements in V O 2 max and muscle hypertrophy in young and older populations after single exercise training (27,62,64,65). These single exercise modes include ambulatory exercise (walking, jogging, and running), cycling, and swimming.

Physiological stimuli necessary for muscle hypertrophy

“…Like cycle training, the discrepancy seems to be due to the length of the training program (6-10 weeks vs. 6 months), as well as training volume per day (20 min vs. 45 min) suggesting the possibility that beyond a certain quantitative threshold, walk training can also increase muscle size in older adults, albeit limited to specific muscle groups. The ES calculated for the study of Kubo et al was 0.30, a similar value as the ES of cycle training in older adults (0.28), yet requiring a much longer period (6 months) than the cycle training (mean period = 14.8 weeks) 8) . The hypertrophic effect of walk training is, therefore, lower than resistance training or cycle training.…”

“…This discrepancy could be due to the total number of sessions constituting the training program, which was less for the study of . We reported that, for untrained subjects, muscle hypertrophy was more likely to take place when the total number of cycle training sessions exceeded 40 times, and this trend was consistent between young and older adults 8) . Resistance training, however, requires fewer sessions until significant muscle hypertrophy is observed (e.g., 18 sessions or 6 weeks) 38) .…”

“…Given the significant role of exercise volume in hypertrophy based on resistance training research, it may be possible that even endurance training, which incurs much less mechanical stress than resistance training, can induce muscle hypertrophy if the volume of work reaches the threshold. In fact, some studies have demonstrated significant muscle hypertrophy after endurance training such as cycling or walking 7,8,31,32) . In this section, we discuss the potential of cycling and walking exercises for inducing muscle hypertrophy.…”

“…over months rather than weeks) 7,8) . This denotes that training quantity or duration, in addition to the degree of mechanical or metabolic stress per session, is a required physiological manipulation for muscle hypertrophy.…”

Prediction and validation of DXA-derived appendicular lean soft tissue mass by ultrasound in older adults

“…Ambulatory activity with moderate and vigorous intensities is positively associated with anterior and posterior lower-leg MT in older women (Abe et al 2012). In addition, our subjects who performed regular cycling (Ozaki et al 2015) and running (Oguri et al 2004) exercise may have prevented the age-related thigh muscle mass loss. Therefore, use of the developed equations in older adults who perform different physical activity must be preceded by their validation in those populations.…”