Joshua Bovard, Daniele A. Cardinale, Filip J. Larsen, Emma Reiter, Mads Jensen-Urstad, Erik Rullman, David Morales-Alamo, Bjorn Ekblom, Jose A. L. Calbet, Robert Boushel. To determine their consequences on exercising hemodynamics with large (e.g., 2-leg cycling (BIKE)) vs. small (e.g., 1-leg knee extension (KE)) muscle mass.Healthy young subjects (4M, 3W) completed BIKE and KE exercise tests.
The femoral artery and vein were catheterized to measure leg blood flow (Q), CaO2, and mean arterial pressure (MAP). Vascular conductance (VC), O2delivery, and leg O2uptake (VO2) were calculated. Measures were normalized to right leg (BIKE) or quadriceps (KE) lean mass. Whole body VO2was measured with a metabolic cart. Men and women were compared at similar and maximal work rates. Body mass was greater in men (M: 80±6 vs. W: 59±12 kg, p=0.03). Although quadriceps mass (3.3±0.2 vs. 2.0±0.3 kg, p less than 0.001) and CaO2were lower, women had a higher mass-specific Q, VC (p=0.054), O2delivery, and leg VO2to maintain whole body VO2during similar KE (Table 1).
These differences were maintained during maximal KE, at which women tended to achieve a higher mass-specific work rate (21±2 vs. 25±3 W·kg-1, p=0.10). They were also apparent during similar BIKE despite a lower leg lean mass in women (8.7±0.3 vs. 5.3±0.7 kg, p less than 0.001). However, the differences were no longer present during maximal BIKE when mass-specific work rate was similar (21±2 vs. 20±2 W·kg-1, p=0.70) and whole body VO2was lower in women.These findings highlight a greaterhemodynamic capacity for women to overcome differences in CaO2and maintain whole body VO2at similar work rates during exercise. They also implicate the quantity of exercising muscle in facilitating the greater hemodynamic capacity and mass-specific workrate during maximal exercise with a small but not large muscle mass.