Combining Aerobic and Resistance Exercise

Browse the Internet for 15 minutes searching information on “Concurrent Exercise” and you will be under impression that combining aerobic and resistance (weight lifting) exercise is all the rage these days.

Enter any larger gym and you’ll see that doing cardio before or after the workout is a new fad.

After all, it’s not so hard to understand the reasons many people love concurrent trainings:

1. They are time saving (one session instead of two)
2. They complement each other and you have a good feeling of full workout
3. Cardio before workout is considered a good warm-up by some
4. Cardio increases metabolic rates

OK, so what’s wrong with concurrent training? Nothing, save for the small detail that it makes your bodybuilding workout ineffective. Yes, not only aerobic exercise interferes with muscle growth, but it can completely reverse the anabolic processes within muscle cells.

Scientific research on concurrent exercise

Study number 1: Concurrent aerobic exercise interferes with the satellite cell response to acute resistance exercise, L. Babcock & colleagues, 2012.

In this extremely interesting paper the authors describe effects of aerobic training, resistance training and combined (concurrent) aerobic/resistance training on the muscle mass, specifically on the stem satellite cells.

Satellite cells are the decisive factor in muscle growth – their proliferation and following merging with muscle fibers is the main muscle growth mechanism. Satellite cells proliferate in response to bouts of heavy resistance exercise.

Now let’s see what happened within the muscle after the three types of exercise (authors obtained muscle biopsies from quadriceps):

Resistance training (weight lifting) – Satellite cell density increased by average 38%

Aerobic training (cycling) – Satellite cell density decreased by average 7%

Combined (concurrent) training – Satellite cell density decreased by average 8%

Nice. So not only combined training doesn’t cause muscle growth, it actually causes net muscle breakdown comparable with aerobic training. So if your aim is to achieve the huge muscle mass of marathon runner, combining cardio with resistance training is the way to go.

As the authors conclude: “Our data indicate that the satellite cell response to resistance exercise is blunted when immediately followed by aerobic exercise, at least in MHC I muscle fibers, and possibly MHC II fibers. This suggests that the physiological environment evoked by aerobic exercise might attenuate the eventual addition of myonuclei important for maximum muscle fiber growth and consequent force-producing capacity.”

Study number 2: Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle, V.G. Coffey & colleagues, 2009.

This Australian study combined heavy resistance exercise (this is almost uniformly some form of quadriceps workout in scientific studies as quadriceps is the largest muscle – this time leg extensions at 80% of 1RM) with repeated sprints.

Again, muscle biopsies were obtained and S6K phosphorylation observed. S6K phosphorylation is recognized as a reliable marker of increased skeletal muscle mass growth.

Now, read carefully: “Specifically, initial resistance exercise increased S6K phosphorylation (approximately 75% P < 0.05), but there was no effect when resistance exercise was undertaken after sprints”.

No slight decrease but NO EFFECT. The conclusion? “Repeated sprints may promote acute interference on resistance exercise responses by attenuating translation initiation signaling and exacerbating ubiquitin ligase expression. Indeed, repeated sprints appear to generate the overriding acute exercise-induced response when undertaking concurrent repeated sprint and resistance exercise.”

The findings are extremely important considering that repeated sprints are quite similar to what many trainees do as a “general warm-up”. This is not 90-minute cardio. It’s just bouts of short aerobic activity.

Study number 3: Acute Neuromuscular and Metabolic Responses to Concurrent Endurance and Resistance Exercise, B.K. Schilling & colleagues, 2012

In this American study authors tried to find out whether the cardio (45 minutes cycling) preceding resistance training (back squat and bench press) impacts the number of maximum repetitions with 80% 1RM.

While cycling didn’t affect the bench press performance, it did affect back squat performance significantly. The same athletes were able to do 26% more repetitions when their leg training was not preceded by cycling.

Obviously, maximum number of repetitions is also indicator or 1RM and of the total performance. If the athlete cannot achieve maximum stimulation during the training the muscle growth will almost surely be negatively affected.

Still not convinced?

Now, let’s look at the combined aerobic and resistance training from the very basic perspective of glycogen depletion. Aerobic training before the resistance training will virtually deplete the muscles of their fuel glycogen. Every activity following this depletion will cause serious muscle breakdown especially (but not only) if you have little body fat.

Aerobic training after the resistance training is not much different. You can improve the overall picture with continuous glycogen replenishment during the workout but this will not completely reverse the catabolism that will inevitably take place (don’t forget that even the resistance training is acutely catabolic – the increased protein synthesis following resistance training is just a chance for the body conditioned by sufficient protein intake.

But as we just learned, this increased protein synthesis is negated by concurrent aerobic activity.

Conclusion

If your training aim is muscle growth, strictly divide your resistance workouts and your cardio workouts. The warming-up should not consist of cycling, running and similar activities. Warming-up is extremely important but it must be short and as much addressing the targeted muscles as possible.

Babcock L, Escano M, D'Lugos A, Todd K, Murach K, Luden N.

Department of Kinesiology, James Madison University, Harrisonburg, Virginia 22807, USA.

2. Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle.

Coffey VG, Jemiolo B, Edge J, Garnham AP, Trappe SW, Hawley JA.

Exercise Metabolism Group, School of Medical Science, RMIT, Melbourne, Australia.

3. ACUTE NEUROMUSCULAR AND METABOLIC RESPONSES TO CONCURRENT ENDURANCE AND RESISTANCE EXERCISE.

Schilling BK, Reed JP, Murlasits Z.

Human Performance Laboratories, Department of Health and Sport Sciences, University of Memphis, Memphis, TN Department of Health and Sport Sciences, University of Memphis, 135 Fieldhouse, Memphis TN