Combining Cardio and Resistance Exercise Disrupts Anabolic Gene Expression!

Breaking News: In this month’s Journal of Applied Physiology, researchers reported that if you are trying to gain muscle mass, combing resistance exercise and cardio in the same session may disrupt genes for anabolism. Previous research has observed only modest hypertrophy with endurance training combined with resistance exercise in skeletal muscle of subjects. Therefore, the possibility exists that the cumulative adaptive effect with consecutive resistance and endurance exercise bouts results in an “interference effect” with concurrent training. Researchers took trained men and assigned them to either one of two conditions: One experimental trial consisted of a bout of resistance exercise followed by a bout of endurance exercise (cycling) while in the other trial subjects performed the reverse exercise order (i.e. endurance then resistance exercise).

Following a standardized warm-up (2 x 5 repetitions at 50% and 60% 1RM, respectively), subjects performed 8 sets of 5 repetitions at ~80% 1-RM. Each set was separated by a 3 min recovery period during which the subject remained seated on the leg extension machine.
Subjects performed 30 min of continuous cycling at a power output that elicited ~70% of individual VO2peak.
Muscle biopsies were taken before, 15 minutes after exercise and 3 hours after exercise. Basically, it’s a “no win” situation no matter which way you look at it. Combing cardio and resistance exercise disrupted genes for muscle anabolism. For example, here is what the researchers found when genes were analyzed:

Cardio before Resistance Exercise- A novel finding was that an endurance bout undertaken prior to resistance exercise suppressed IGF-I Ea (a gene splice of IGF-1) mRNA (-42%) and also induced small declines in Mechano Growth Factor (-27%). The findings of the present study represent the collective effect of diverse contraction modes and it is tempting to speculate that endurance exercise immediately preceding resistance exercise attenuates the anabolic response.

Resistance Exercise then Cardio- Cardio performed after resistance exercise increased genes for muscle tissue breakdown. For example, muscle breakdown genes were elevated Atrogin (21%) and MuRF (53%) mRNA when cycling was performed subsequent to resistance exercise. Previous studies have shown that Atrogin and MuRF mRNA (genes for muscle tissue breakdown) following a single bout of endurance exercise were elevated. Thus, the results indicate that endurance activity after resistance training may have the capacity to exacerbate the genes for catabolism and subsequent protein degradation. Consequently, when resistance exercise is undertaken after endurance exercise, up-regulation of ubiquitin ligase expression may be suppressed. Moreover, PGC-1a mRNA which is a gene that turns “on” an aerobic phenotype was elevated when cycling preceded resistance exercise.

In summary, the results indicate that endurance activity performed prior to resistance exercise may diminish the anabolic response while performing endurance after resistance exercise may exacerbate inflammation and protein degradation. The results provide support for the contention that (acute) combing cardio and resistance exercise training back to back does not promote optimal activation of anabolic pathways. Thus, undertaking both resistance exercise/cardio together in close proximity influences the acute molecular profile and likely exacerbates acute “interference” of key anabolic signaling pathways.

If you going to do cardio, it may be better to perform it earlier or later in the day as opposed to doing it before or after resistance exercise for an optimal anabolic effect.

Comments or Opinion on this study?

J Appl Physiol. 2009 Jan 22. [Epub ahead of print]

Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle.
Coffey VG, Pilegaard H, Garnham AP, O’Brien BJ, Hawley JA.
RMIT University.
We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men (22.9 +/- 6.3 yr, body mass 73.2 +/- 4.5 kg, VO2peak 54.0 +/- 5.7 mL(.)kg(-1)(.)min(-1)) were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1RM) followed by a bout of endurance exercise (30 min cycling, 70% VO2peak), or vice-versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout and following 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1 (ser473) were elevated 15 min after resistance exercise but not cycling, with the greatest increase observed when resistance exercise followed cycling (~55%, P