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Tuesday, January 8, 2013

Does aerobic exercise training act synergistically with resistance to promote hypertrophy? New findings & challenges


Tommy Lundberg and colleagues from Mid Sweden University published a nice study in the first issue of the Journal of Applied Physiology for 2013. Their hypothesis was that aerobic exercise training (AT) will act synergistically with resistance training (RT) to promote muscle hypertrophy. Although contradictory to the general view, this hypothesis was based on recently published data by the same group showing an enhanced protein synthesis in response to knee extensors RT performed 6 hours after AT on the cycle ergometer compared with RE only (Lundberg et al., 2012).
What they did in the 2013 study?
·         10 moderately trained men with modest experience to weight training who had performed no regular RT before volunteered for this study.
·         Individuals performed 5 week unilateral knee extension aerobic and resistance training (AT+RT) while the contralateral leg performed RT only.
·         RT was performed 6hr after AT.
·         Individuals performed 15 AT and 12 RT sessions and showed 100% compliance to the program.
·         Quadricep femoris volume and cross sectional area, isokinetic strength and power and endurance were evaluated before and after training.

Main findings
·         A greater increase in quadriceps muscle volume after RT+AT compared with RT (13.6% vs 7.8%, respectively). All individuals presented greater increases in muscle volume with RT+AT.
·         Normalized torque (Nm/cm2) increased less –though not significantly- after RT+AT (12%) compared with RE (19%).
·         Increases in isokinetic peak torque were also similar across velocities for both RT+AT and RT.
·         These findings suggest that muscle hypertrophy observed after AT+RT dissociated from the gains in muscle strength and power. In fact, the gain in muscle strength and power tended to be greater with RT.

Implications for football training & take-home message
It seems that concurrent aerobic and resistance training might promote hypertrophy at least in moderately trained individuals. We don’t know if this holds true for well-trained football players or individuals. However, this hypertrophy might not be translated into greater gains in strength & power.

Implications for the general population
Individuals might benefit from concurrent aerobic and resistance training since they might gain more muscle mass compared to resistance training only. Fat mass increment is important to combat excess body weight and fat by promoting a greater metabolic rate and to improve glucose metabolism.

Points to keep in mind
Aerobic training was contacted for a single “isolated” muscle group using a very well controlled experimental set-up (one-legged cycle exercise).
Moderately trained individuals took part in the study and this might affect generalization of these findings to other populations and sports.

References
Lundberg et al. Aerobic exercise alters skeletal muscle molecular responses to resistance exercise. Med Sci Sports Exerc 44: 1680-1688, 2012.
Lundberg et al. Aerobic exercise does not compromise muscle hypertrophy response to short-term training. J Appl Physiol 114: 81-89, 2013.

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