Sex differences in the oxygen delivery, extraction, and uptake during moderate-walking exercise transition

Abstract

Previous studies in children and older adults demonstrated faster oxygen uptake (V̇O) kinetics in males compared with females, but young healthy adults have not been studied. We hypothesized that young men would have faster aerobic system dynamics in response to the onset of exercise than women. Interactions between oxygen supply and utilization were characterized by the dynamics of V̇O, deoxyhemoglobin (HHb), tissue saturation index (TSI), cardiac output (Q̇), and calculated arteriovenous O difference (a-vO) in women and men. Eighteen healthy active young women and men (9 of each sex) with similar aerobic fitness levels volunteered for this study. Participants performed an incremental cardiopulmonary treadmill exercise test and 3 moderate-intensity treadmill exercise tests (at 80% V̇O of gas exchange threshold). Data related to the moderate exercise were submitted to exponential data modelling to obtain parameters related to the aerobic system dynamics. The time constants of V̇O, a-vO, HHb, and TSI (30 ± 6, 29 ± 1, 16 ± 1, and 15 ± 2 s, respectively) in women were statistically (p < 0.05) faster than the time constants in men (42 ± 10, 49 ± 21, 19 ± 3, and 20 ± 4 s, respectively). Although Q̇ dynamics were not statistically different (p = 0.06) between groups, there was a trend to slower Q̇ dynamics in men corresponding with the slower V̇O kinetics. These results indicated that the peripheral and pulmonary oxygen extraction dynamics were remarkably faster in women. Thus, contrary to the hypothesis, V̇O dynamics measured at the mouth at the onset of submaximal treadmill walking were faster in women compared with men.

Sex differences in fatigability and recovery relative to the intensity–duration relationship

“…), then a 5 s rolling average was used to smooth the data (Beltrame et al . ), before 30 s time intervals were taken pre‐exercise, 25, 50, 75 and 100% of time to task failure. Pre‐exercise, participants remained seated for 5 min to establish baseline values, with the final 30 s used as pre‐exercise values.…”

“…This technique has previously been validated and shown to be reliable at rest and in exercise conditions (Parati et al 1989;Waldron et al 2017). Signals were linearly interpolated and resampled at 1 Hz (Faisal et al 2009), then a 5 s rolling average was used to smooth the data (Beltrame et al 2017), before 30 s time intervals were taken pre-exercise, 25, 50, 75 and 100% of time to task failure. Pre-exercise, participants remained seated for 5 min to establish baseline values, with the final 30 s used as pre-exercise values.…”

Physiological sex differences affect the integrative response to exercise: acute and chronic implications

“…For instance, female vastus lateralis muscles are consistently shown to have a 7–23% greater proportional area of type I muscle fibres (Roepstorff et al., 2006; Simoneau & Bouchard, 1989; Staron et al., 2000). The consequences of this greater proportion of type I fibres are multifactorial; in terms of muscle metabolism during exercise, females oxidize more fat but less carbohydrate and amino acids compared with males (Tarnopolsky, 2008) and demonstrate faster oxygen uptake () kinetics during moderate exercise intensities (Beltrame, Villar, & Hughson, 2017). This is probably attributable to the fact that males have greater glycolytic capacity (Esbjörnsson, Sylvén, Holm, & Jansson, 1993), whereas females have greater whole‐muscle oxidative capacity (Russ, Lanza, Rothman, & Kent‐Braun, 2005).…”

<p>Association Between the Predictors of Functional Capacity and Heart Rate Off-Kinetics in Patients with Chronic Obstructive Pulmonary Disease</p>

“…34 The exponential modeling was performed using a specific routine developed in the software CardioKin 1.2, according to the parameters calculated by a certified LabVIEW-associated developer (LabVIEW 2012, National Instruments, Austin, TX, USA), which follows the pattern of Levenberg-Marquardt. 35 …”