Dual effect of activity levels and temperature step-change on human comfort and recovery time: Simulated short-term commute in winter

Individuals living in a location with access to public transport and a short distance from the workplace tend to walk for short commuting. Human activity levels are affected by the rate of walking while commuting, which affects thermal comfort and response. To investigate the human thermal response in commuting, a climate chamber experiment was conducted to simulate outdoor commuting (13 °C) and indoor rest recovery (24 °C) in winter. Standing and walking at 4 and 6 km/h were used to simulate temporary rest, walking, and running, respectively. Twenty healthy participants were asked to simulate commuting (13 °C) with standing/low, 4 km/h/medium, and 6 km/h/high activity levels for 8 min and sitting (24 °C) for 32 min. The physiological parameters and subjective perceptions of the subjects were recorded. The results showed that there were differences in the sensitivity of the parameters to changes in activity levels and temperature steps. Thermal sensation and mean skin temperature responded considerably to the dual effect of activity levels and temperature up-step; however, blood pressure was exclusively sensitive to temperature step-change. The elevated activity level of 1 met may increase the recovery time by 5–10 min. Functional paradigms for psychological and physiological recovery times in a neutral environment were developed, which could provide a potential solution for improving thermal satisfaction and the assessment of recovery times. The results of this study will guide improvement strategies for physiological recovery and thermal comfort after commuting.