G. D'Hulst, Exercise Physiology Research Group, KU Leuven
Can we get bigger muscles from endurance cycling? And is there any difference between high-intensity and low-intensity cycling? In an attempt to provide an answer on this question, Canadian researchers recently performed a study in 8 moderately trained cyclists (Di Donato et al. 2014). The two trials were ‘energy-matched’: the subjects expended an identical amount of energy during the two sessions (~88 kcal) because exercise duration in LOW was twofold longer than in HIGH. Muscle myofibrillar and mitochondrial protein synthesis rates were measured. The former leads to an increase in cross-sectional area of the muscle fiber, the latter elevates the amount of mitochondria or the ‘energy factories’ of the muscle cell.
Myofibrillar protein synthesis was elevated during the initial 4.5 hours of recovery after both LOW and HIGH cycling. However, only HIGH cycling elicited increased rate of myofibrillar protein generation for more than 24 hours. By analogy, HIGH also stimulated mitochondrial protein synthesis till 24h after HIGH but not following LOW (see figure).
From Di Donato et al. 2014 (Reference: see below)
Take home message: can cycling generate bigger muscles? Most likely, yes, and the current study suggests that short high-intensity cycling exercise is more productive than low-intensity exercise to stimulate muscle contractile protein synthesis and thereby eventually increase muscle volume.
Di Donato, D. M., West, D. W., Churchward-Venne, T. A., Breen, L., Baker, S. K. & Phillips, S. M. 2014. Influence of aerobic exercise intensity on myofibrillar and mitochondrial protein synthesis in young men during early and late post-exercise recovery. Am.J.Physiol Endocrinol.Metab.