Blood flow resistance training has been suggested to improve muscle strength and size at lower loads due to similar hormonal releases compared to resistance training. This acute hypoxia has stemmed research on systemic hypoxia.
Training in systemic hypoxic conditions is also suggested to improve growth hormone (GH) release. However, the effects of systemic hypoxic conditions have yet to be determined.
This study “examined the effects of low-intensity resistance exercise under acute systemic hypoxia on metabolic and hormonal responses”.
What was done
Eight active male subjects visited the laboratory to evaluate 1RM for bench press and bilateral leg press under normoxic conditions. Then, subjects performed low-intensity (50% of 1RM) bench press (5 sets ) and bilateral leg press (5 sets) exercises while breathing normoxic air (approximately 20% oxygen) and hypoxic air (13% oxygen) with blood taken before and 15 minutes after hypoxic and normoxic conditions and 0, 15, and 30 minutes after exercise. GH, norepinephrine (NE), testosterone (T), cortisol, blood lactate (LA), and subjective fatigue were measured.
Then the subjects returned to the laboratory for the two trials:
- Resistance exercise while breathing room air (NR)
- Resistance exercise while breathing hypoxic (HR)
Both resistance training protocols included bench press and leg press, each with 14 repetitions for 5 sets at 50% 1RM.
Significant changes were noted in specific oxygen levels in the HR trial. A significant difference was noted in blood LA. GH secretion was significant in the HR trial at 0 and 15 minutes after exercise. No differences were noted in cortisol, but NE and T were significantly different in both trials after resistance training. Subjective fatigue increased in both groups but was significantly different.
This study suggests performing low-intensity resistance training under system hypoxic conditions results in similar results to local ischemic conditioning in a hormonal release. These researchers suggest their results may help athletes in sports where resistance training during the season is essential for maintaining muscle mass.
In swimming, out of water strength has yet to be correlated with swimming success. Therefore, these applications outside of the pool may have a minimal contribution. Moreover, future studies on systemic hypoxia need to use performance and strength as dependent variables.
- Kon M, Ikeda T, Homma T, Suzuki Y. Effects of low
intensity resistance exercise under acute systemic hypoxia on hormonal responses. J
Strength Cond Res. 2012 Mar;26(3):611-7.