Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Abstract

The intensity of large muscle mass exercise declines at altitude due to reduced oxygen delivery to active muscles. The purpose of this investigation was to determine if the greater limb blood flow during single-leg cycling prevents the reduction in tissue oxygenation observed during traditional double-leg cycling in hypoxic conditions. Ten healthy individuals performed bouts of double and single-leg cycling (4, four-minute stages at 50–80% of their peak oxygen consumption) in hypoxic (15% inspired O2) and normoxic conditions. Heart rate, mean arterial pressure, femoral blood flow, lactate, oxygenated hemoglobin, total hemoglobin, and tissue saturation index in the vastus lateralis were recorded during cycling tests. Femoral blood flow (2846 ± 912 mL/min) and oxygenated hemoglobin (−2.98 ± 3.56 au) during single-leg cycling in hypoxia were greater than double-leg cycling in hypoxia (2429 ± 835 mL/min and −6.78 ± 3.22 au respectively, p ≤ 0.01). In addition, tissue saturation index was also reduced in the double-leg hypoxic condition (60.2 ± 3.1%) compared to double-leg normoxic (66.0 ± 2.4%, p = 0.008) and single-leg hypoxic (63.3 ± 3.2, p < 0.001) conditions. These data indicate that while at altitude, use of reduced muscle mass exercise can help offset the reduction in tissue oxygenation observed during larger muscle mass activities allowing athletes to exercise at greater limb/muscle specific intensities.

The Improvement in Exercise Performance during Reduced Muscle Mass Exercise is Associated with an Increase in Femoral Blood Flow in Older and Younger Endurance-Trained Athletes

“…To our knowledge, this is the first study to show that femoral blood flow was greater in response to maximal SL compared with DL cycling in both older and younger trained populations. Yet, these results are in agreement with observations of greater femoral blood flow during SL cycling in a limited cohort of healthy (n = 4) and clinical (patients with heart failure, n = 5) individuals (LeJemtel et al, 1986) and after submaximal SL cycling exercise (Burns et al, 2014;Draper et al, 2022). As such, this study supports the finding that a transition from large to small muscle mass exercise may allow for a greater peripheral hyperaemic response (Calbet et al, 2009;Cardinale et al, 2019;Klausen et al, 1982).…”

“…Indeed, it has been shown that power output per leg is generally 5 to 10% greater during single-leg (SL) compared with double-leg (DL) cycling (Abbiss et al, 2011;Gordon et al, 2018;Iannetta et al, 2019). Yet, blood flow during maximal SL and DL cycling has only been assessed in a small clinical population (LeJemtel et al, 1986) or during submaximal exercise (Burns et al, 2014;Draper et al, 2022). Therefore, the improved capacity to increase blood flow and enhance oxygen delivery during a maximal cycling exercise performed using SL compared to DL remains to be demonstrated.…”