Tuesday, June 2, 2015

In Untrained Subjects, Circuit Training Rocks! Study Shows Similar Strength & Better Aerobic Performance Gains W/ Circuit vs. Combined Resistance & Aerobic Training

If you are just starting out on your way to build a body like this, there's little doubt that circuit training is worth considering. If you are more advanced and have a priority on strength and muscle gains, things may be different.
This is not the first article about the benefits of circuit training here at the SuppVersity. It is however one of the most convincing ones, as far as the the choice between time-efficient circuit training regimen and a more time-consuming classic resistance training + aerobic training combo is concerned.

To test, which of the two regimen is "better, the subjects of the study, 34 sedentary young women (20.9 +/- 3.2 years; 167.6 +/- 6.4 cm; 65.0 +-/ 15.2 kg), were assigned to either (a) a combined resistance and aerobic exercise group (COMBINED; n = 17) or (b) a circuit-based whole-body aerobic resistance training circuit group (CIRCUIT; n = 17).
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All subjects, regardless of which group (for a detailed description of the training protocols see Figure 1) they'd been assigned to trained 3 days per week for 5 weeks.
Figure 1: Tabular overviews of the two training protocols; the COMBINED training group did 30 minutes of resistance training followed by 15 minutes of aerobic exercise (Myers. 2015).
The study outcomes included pre- and post-training measures including VO2peak, anaerobic Wingate cycling, and muscular strength and endurance tests. Tests that revealed that...
  • Figure 2: Selected study results (Myers.2015).
    the aerobic performance, as measured by the VO2peak pre- vs. post-test, increased exclusively in the CIRCUIT group (11%),
  • peak and relative average power increased to similar extents in both groups, i.e. by 5% (p = 0.027) and 3.2% (p = 0.006), respectively, in the CIRCUIT group and by 5.3% (p = 0.025) and 5.1% (p = 0.003) in the COMBINED training group, 
  • a slightly greater inter-group difference was observed for the chest and hamstrings 1 repetition maximum (1RM) which improved by 20.6% (p = 0.011) and 8.3% (p = 0.022) in the CIRCUIT and by 35.6% (p , 0.001) and 10.2% (p = 0.004) in the COMBINED group, respectively,
  • the most significant advantage of the COMBINED training group, was observed for the back (11.7%; p = 0.017) and quadriceps (9.6%; p = 0.006) 1RM, which did not improve in the CIRCUIT group, 
so that it may eventually still be a question of priorities. Or, practically speaking, a decision between a "cardio" and "strength" focus - only the negative effect of COMBINED training on VO2 max may come as a small surprise (small, since 15 minutes of medium intensity exercise are like no cardio).
Keep in mind that the subjects were untrained: I wouldn't say that it is impossible for a trained person to increase his / her VO2 max with circuit training, but if you want to do so, you will certainly have to incorporate a lot of high intensity body weight exercises and minimize rest extremely. Fur-thermore, the strength advan-tage of "real" resistance training regimen will increase, the more advanced you are. In other words: If you've been training for 2-3 years, now, don't scrap your regular routine for circuit training unless you want to use it as a means to mix things up or taper.
So what? In spite of the fact that the inter-group difference may have been smaller than many of you probably expected, common wisdom prevails: If you want maximal strength gains, there is no way you can skip classic resistance training regimen. What is the truly surprising results of the study at hand is thus not the lack of quads and back 1RM strength gains in the CIRCUIT group, but the absence of VO2 increases in the COMBINED group.

Simply adding in 15 minutes of "cardio" after your resistance training protocol is as effective as doing nothing. So, if you want the best of both worlds, you better HIIT the gym (i.e. do HIIT training) on two of your "off days". As I've pointed out in numerous previous articles, 10 intervals and a 20 minute workout may suffice to trigger significant increases in VO2max and, let's be honest, you can squeeze that into even the tightest schedule, can't you | Comment on Facebook!
References:
  • Myers TR, Schneider MG, Schmale MS, Hazell TJ. Whole-body aerobic resistance training circuit improves aerobic fitness and muscle strength in sedentary young females. J Strength Cond Res. 2015 Jun;29(6):1592-600.