Correlation between maximal aerobic power and longitudinal vital signals during high-intensity activities of daily living

Abstract

Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): São Paulo Research Foundation (FAPESP);Coordination for the Improvement of Higher Education Personnel (CAPES) Background Higher activity levels are linked with better cardiovascular health. Maximum aerobic power (measured by the maximal oxygen uptake, VO2max) obtained during cardiopulmonary exercise testing (CPET) is an index of cardiovascular health and represents the maximum ability of the aerobic system to supply energy. Moreover, it is known that high-intensity activities of daily living (hiADL) are associated with higher VO2max, and were three times more beneficial than low-intensity activities, such as light walking. However, little is known about the physiological responses during these hiADL that are associated with better health outcomes. So far, only the levels and intensities of the physical activities have been investigated, but the physiological responses at these activities remain unclear. Purpose Verify the associations between VO2max and longitudinal vital signals from wearables during hiADL. Methods 43 volunteers (32 males, 39.91±15.87 years; 75.41±13.12 kg; 173.67±9.04 cm) with different levels of VO2max (31.08±8.73 ml/kg/min) wore a wearable device (smart t-shirt, Hexoskin) with embedded cardiac, respiratory, and movement sensors to collect unobtrusive data for 7 days (9.31±1.36 hours per day). These sensors continuously measure heart rate (HR), breathing rate (BR), minute ventilation (VE), tidal volume (Vt), hip acceleration (ACC), and walking cadence (Cad). The hiADL were classified based on the Cad response where values higher than 124 steps per minute were labelled as hiADL. At hiADL, the average response for all variables was calculated. Finally, the Pearson or Spearman correlations were computed considering a statistical significance level of 5%. Results hiADL corresponded to just 1% of the physical activities (or 35.11±43.30 minutes per week). The average response of the vital signals at hiADL were: HR (118.2±20.36 bpm), BR (30.7±8.0 rpm), VE (52.21±35.54l), Vt (1.63±0.71 l/min), Acc (0.87±0.6g), and Cad (143.69±10.13). The correlations were statistically (p<0.05) high and positive between VO2max and BR, VE, Vt, and Cad; also, moderate, and positive between VO2max and HR and with the percentage of the time spent at hiADL, as described in figure 1. Conclusion The VO2max (or cardiovascular health) is related to the time spent in hiADL and with the hemodynamic and respiratory response magnitudes at these high-intensity activities.