Athletes want to be the Jack of all trades—conditioned, strong, fast and muscular. The problem is, it’s tough to gain muscle and get in good cardiovascular shape at the same time. But since athletes can’t skip out on either, how you structure your training is critically important.
It’s not at all uncommon to see people, particularly at commercial gyms, perform a muscle-building strength workout and immediately follow that up with a prolonged jog on the treadmill or extended session on the stationary bike. In theory, it makes sense: while strength training movements largely target the anaerobic energy systems, endurance exercise largely target the aerobic energy systems. Performing both in the same workout seems like a recipe for ultra-efficient training.
However, the reality doesn’t seem to be quite so simple. A recent study published in the Journal of Sports Science & Medicine examined this type of training and found that it can seriously hamper your post-exercise muscle growth. Let’s summarize the results.
Fourteen young men (~22 years old) trained for eight weeks, with two strength training sessions and two aerobic (conditioning) training sessions per week.
The strength training sessions consisted of Machine Preacher Curls for consistently more sets of 10 repetitions, progressing in weight as strength increased.
The conditioning sessions consisted of moderate intensity aerobic training for 30 minutes.
All subjects performed both workouts, but were separated into two groups:
Concurrent group: Performed cardio immediately following strength training
Separate day group: Performed cardio at least 24 hours after strength training
Both groups saw similar improvement in their upper-body strength throughout the study. However, the separate day group experienced significantly greater hypertrophy (muscle gain) than the concurrent group (~12% vs. ~5%). That’s over double the gains!
To maximize muscle gain, avoid performing cardio directly after weight training. For the best case scenario, perform them on separate days. Spacing them out by several hours could also mitigate any inhibition of muscle growth. Timing conditioning workouts away from lifting sessions is a simple way to optimize muscle gains. This is a classic example of how working harder does not always equate with better gains. The athlete who combines strength training and cardio in the same session is certainly in for longer and more arduous workouts, yet they actually have less to show for it.