The Effect Of Compression Sleeves On Muscle Oxygen Saturation, Stroke Volume, And Metabolism During Graded Exercise In Acute Hypoxia

Reduced partial pressure of oxygen at altitude reduces the amount of oxygen able to be delivered to exercising muscles. Interventions to restore muscle oxygen saturation (SmO2) during hypoxic exercise have the potential to improve related measures like cardiac output and VO2. PURPOSE: Our study explored the effects of lower leg compression sleeves on SmO2, stroke volume, and metabolism during graded exercise in acute, normobaric hypoxia. METHODS: Seven male participants were recruited (Age = 24.5 ± 3.2; Bodyfat % = 21.8 ± 2.7; VO2max = 42.2 ± 7.1 ml/kg/min) and underwent two graded exercise bouts at 20%, 40% and 60% of sea level VO2max in normobaric hypoxia (13.5% FiO2). During one session, participants wore compression sleeves from their lower ankle to upper calf. Each session consisted of a 20 minute rest in hypoxia before cycling began. Each stage was 4 minutes long, and a 10 minute recovery period was completed in hypoxia. SmO2 was measured in the quadriceps and gastrocnemius. A physioflow impedance cartography device and a metabolic cart were used for measuring cardiovascular and metabolic variables. All measurements were recorded through rest, exercise, and recovery stages of the session. RESULTS: Compression sleeves increased SmO2 of the gastrocnemius at rest (57.2% vs 36.7%; p = 0.01), but not during exercise (p > 0.05). Similarly, SmO2 of the quadriceps was increased with compression sleeves at 20% VO2max (49.2% vs 36.5%; p = 0.02), but all other time points were similar (p > 0.05). There was no difference in heart rate (115 ± 35 vs 113 ± 34 beats/min; p > 0.05), stroke volume (155 ± 47 vs 140 ± 42 ml/beat; p > 0.05) or cardiac output (18.7 ± 9.4 vs 16.4 ± 8.1 L/min; p > 0.05) across conditions. Metabolism (VO2 1.2 ± 0.7 vs 1.2 ± 0.6 L/min; p > 0.05) and ventilation (44.7 ± 26.8 vs 44.1 ± 27.1 L/min; p > 0.05) were not affected by compression sleeves. CONCLUSIONS: These results indicate that compression sleeves can improve muscle oxygen saturation at rest and during low intensity exercise in hypoxia. The improvements in SmO2 do not seem to be the result of enhanced venous return, and have no impact on metabolism.