Pulmonary V̇O2 on-kinetics and walking net V̇O2 associate with fatigue and mood disturbance in postmenopausal women

Abstract

Postmenopausal women often experience fatigue and mood disturbance both of which interfere with quality-of-life. Since greater physical function aids psychosocial well-being, we hypothesized the acute cardiopulmonary responses during walking may reveal important factors linked to fatigue and mood disturbance. In this cross-sectional study, women of similar body mass index (BMI) aged 55-75 y were dichotomized to mid-life (55-65 y; 83.4 ± 8.4 kg/m2; n = 14) or older (≥65 y; 81.8 ± 10.4 kg/m2; n = 11) groups. A 6-minute walk test was used to estimate peak aerobic capacity (V̇O2peak). A treadmill task coupled with indirect calorimetry measured mean response time (MRT) - representing the duration to reach 63 % of steady-state net oxygen uptake (V̇O2). Average daily fatigue and fatigue interference were measured with the Fatigue Symptom Inventory. General mood disturbance was measured with the Profile of Mood States (POMS) questionnaire. Age-group differences were not detected in fatigue ratings, MRT, or walking net V̇O2. However, older women had lower aerobic capacity (p = 0.002, ES = 1.39) and greater disturbance in the POMS Depression-Dejection subscale (p = 0.042, ES = 0.41). Among all participants, and independent of V̇O2peak, MRT correlated with average daily fatigue (r = 0.500, p = 0.015), fatigue interference (r = 0.421, p = 0.046), and POMS total mood disturbance (rs = 0.437, p = 0.037). Regression modeling revealed MRT and walking net V̇O2 jointly explained 55 % (R = 0.744, p < 0.001) of the variance in average daily fatigue. In conclusion, MRT and walking net V̇O2 may serve as important points of intervention to alleviate fatigue and mood disturbance in postmenopausal women.