|In hypoxia you still have to work out intensely & consistently to get shredded.|
The article discusses the results of a recent study from the Journal of Strength and Conditioning Research by Yan et al. In said study, the authors tested the effects of different levels of systemic hypoxia on the hormonal responses, strength, and body composition to 5-week resistance training.
To this ends, Yan et al. recruited twenty-five "physically active" male subjects with previous resistance training experience and randomly assigned them to one out of 3 experimental groups that performed 10 sessions (2 sessions per week) of barbell back squat (10 repetitions, 5 sets, 70% 1 repetition maximum [RM]) under
- normoxia, i.e. in a regular gym (NR, FiO2 = 21%), or
- severe (HH) or moderate (HL) hypoxia (HL, FiO2 = 16%; HH, FiO2 = 12.6%).
|Figure 1: Hormonal response to resistance training under normal or reduced oxygen conditions; inerestingly, the effects on the testosterone / cortisol ratio increased, while those on GH decreased over time (Yun. 2015).|
But you recently wrote that the hormonal response doesn't matter! Yes, I did. Actually, that's not even long ago (read up on it), but who said that the changes you see in Figure 1 mechanistically caused the increased adaptive response? That must have been the little bro in your ear, because I certainly didn't do so. With regard to growth hormone, we need to be careful, anyway. In the year 2000, Raastad et al (2000) already demonstrated that the growth hormone response to one and the same resistance training protocol is highly individual with both responders and nonresponders. Furthermore, the GH response has been shown to increase with intensity and glycogen demands and the latter are obviously increased when a lack of oxygen in the blood reduces the efficacy of the citric acid cycle. The study at hand does therefore not contradict the results of the study at hand that Ho et al. didn't find similar effect on GH with a low-intensity resistance training protocol in normoxia vs. hypoxia (Ho. 2014). In fact, the differential response would rather support the hypothesis that the different hormonal response is a correlate, not a trigger of the improved adaptational response in the Yun study.In view of the fact that we are dealing with a moderate-intensity resistance training program, the former is as unsurprising as the significant isometric strength increases and lean mass changes in hypoxia are surprising.
|Figure 2: Rel. Changes in strength and body composition over the course of only 5 weeks of training (Yan. 2015); please note that the absolute reduction in BF% was only 2% in the hypoxia and 1% in the normoxia group/s.|
|The mask on the right does not simulate training in hypoxia and cannot be expected to help effortlessly shed 11% of body fat as it was observed in a 2013 study in trained athletes.|
- Ho, Jen-Yu, et al. "Effects of acute exposure to mild simulated hypoxia on hormonal responses to low-intensity resistance exercise in untrained men." Research in Sports Medicine 22.3 (2014): 240-252.
- Kon, Michihiro, et al. "Effects of systemic hypoxia on human muscular adaptations to resistance exercise training." Physiological reports 2.6 (2014): e12033.
- Raastad, Truls, Trine Bjøro, and Jostein Hallen. "Hormonal responses to high-and moderate-intensity strength exercise." European journal of applied physiology 82.1-2 (2000): 121-128.
- Stuessi, Christoph, et al. "Respiratory muscle endurance training in humans increases cycling endurance without affecting blood gas concentrations." European journal of applied physiology 84.6 (2001): 582-586.
- Yan, Bing, et al. "Effects of Five-Week Resistance Training in Hypoxia on Hormones and Muscle Strength." The Journal of Strength & Conditioning Research 30.1 (2016): 184-193.