Aerobic fitness as a parameter of importance for labour loss in the heat

Objectives To derive an empirical model for the impact of aerobic fitness (maximal oxygen consumption; V̇O2max in mL∙kg−1∙min−1) on physical work capacity (PWC) heat. Design Prospective, repeated measures. Methods Total completed during 1 h treadmill walking at a fixed heart rate 130 b∙min−1 was assessed 19 young adult males across variety warm and hot climate types, characterised by wet-bulb globe temperatures (WBGT) ranging from 12 to 40 °C. For data presentation obtaining initial parameter estimates modelling, participants were grouped into low (n = 6, 74 trials), moderate 8, 76 high 5, 29 trials) fitness, with group mean 42, 52, 64 mL∙kg−1∙min−1, respectively. heated conditions (WBGT 18 °C), we calculated PWC% expressing total energy expenditure (kJ above resting) each trial relative that achieved cool reference condition °C 100% PWC). Results The reduction (PWC%) caused heat significantly smaller up 16% fit compared those lower capacity. also modulated relationship between sweat body temperature changes increasing WBGT. Including individual PWC prediction increased predicting power 4%. Conclusions Incorporating improved predictive stress index WBGT Physical Work Capacity largest observed 25 35