|The results of the study and hand strongly suggest, but don't finally prove that a brief leg-focused HIIT like spinning will not impair your biceps gains even if it's done immediately before weight training.|
Now, a recent study from the Swedish School of Sport and Health Sciences shows that the question whether "cardio" in the broadest sense will interfere with strength training gains cannot be answered with a simple yes or no.
In their study, Moberg, et al. (2014)set out to conduct a series of studies to examine the influence of endurance exercise on the acute stimulatory effect of resistance exercise on anabolic processes. To this ends, the effect of endurance exercise on a previously inactive muscle was investigated. The aim was to examine the influence of resistance exercise on mTORC1-signaling and rate of protein synthesis in the triceps brachii muscle with or without preceding intervals of high-intensity cycling.
Eight trained males performed, in a randomized fashion, two sessions of heavy resistance exercise (RE) with the triceps muscles, where one session was preceded by intervals of high-intensity cycling (E+RE), 5 x 4 min at 85% of VO2 peak. Mixed muscle protein fractional synthetic rate (FSR) was measured at rest, prior to exercise, and during a 3 hour recovery period following exercise by continuous infusion of L-[ring-13C6] phenylalanine. Muscle biopsies from the triceps brachii was collected twice at rest separated by three hours, directly after resistance exercise and following 90 and 180 min of recovery. Signalling in the mTORC1-and AMPK-pathway was assessed using western blot technique.
|Individual and group mean increase (%) in m. quadricep muscle volume following resistance training with (AE+RE) or without (RE) concurrent aerobic exercise (Lundberg. 2013).|
|Figure 1: Fractional muscle protein synthesis response in the biceps brachii and corresponding changes in signalling proteins in the HIIT + resistance training (E+RE) and the resistance training only trial (Moberg. 2014).|
The same goes for the signalling protein AMPK and eEF2, as well as for the alleged protein synthesis gauge mTOR which was increased by 76% and 108% above rest directly after the E+RE and RE, respectively, and remained elevated in both trials during the entire recovery period.
- Lundberg, Tommy R., et al. "Aerobic exercise does not compromise muscle hypertrophy response to short-term resistance training." Journal of Applied Physiology 114.1 (2013): 81-89.
- McCarthy, J., et al. "Combined strength and endurance training: Functional and morphological adaptations to ten weeks of training." No. NHRC-92-26. Naval Health Research Center San Diego CA, 1992.
- Moberg, Marcus, et al. "High-intensity cycling performed prior to resistance exercise does not influence mTORC1-signaling and the rate of muscle protein synthesis in the triceps brachii." 19th annual Congress of the European College of Sport Science, 2-5 July 2014, Amsterdam The Netherlands. 2014.