Even when the air has the same amount of oxygen, breathing it through a mask at low pressure makes your body produce less lactic acid and keeps your heart rate lower during weightlifting than being at real high altitude.
Scientific Claim
At an equivalent FiO₂ of 15.9%, normobaric hypoxia results in lower maximal blood lactate concentrations (ES = 1.01–1.25) and lower rest-phase heart rate (ES = 0.80–0.83) compared to hypobaric hypoxia during resistance training, indicating reduced metabolic stress and cardiovascular strain despite similar oxygen availability.
Original Statement
“Compared to HH, NH showed a moderate reduction in the inter-set rest-HR (ES > 0.80), maxLac (ES > 1.01) and SmO₂ (ES > 0.79) at both rest intervals.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The RCT design with direct physiological measurements and large effect sizes (ES > 1.0) supports definitive causal claims about differential metabolic and cardiovascular responses between hypoxia types.
Evidence from Studies
Supporting (1)
The study found that when people exercised in low-oxygen air at the same oxygen level, those in the normal-pressure environment (normobaric) had lower heart rates and less lactic acid buildup than those in low-pressure air (hypobaric), meaning their bodies were under less stress.