Consequences of police-related personal protective equipment and physical training status on thermoregulation and exercise energy expenditure.

Background: The aim of this study was to examine the impact of personal protective equipment (PPE) on human thermoregulation and its alteration in groups of different training status.

Methods: Forty-five men performed a maximum voluntary contraction test in an upright pull position to determine lower body strength and a graded treadmill test to determine maximum oxygen uptake (V̇O2max). Body composition was estimated via bioelectric impedance analysis. According to specific cutoff values, participants were assigned to a group of endurance-trained, strength-trained, endurance- and strength-trained, or untrained individuals. Subsequently, they completed two graded exercise tests until volitional exhaustion, once wearing sports wear (SPW) and once wearing PPE (20.9 kg). Participants were weighed before and afterward to investigate sweat loss and sweat rate. Body temperature was measured continuously from the tympanic membrane. Energy expenditure was derived from breathing gas analysis.

Results: Sweat rate was 91% higher in PPE than in SPW but not significantly different between groups (P>0.05). Body temperature was significantly higher in PPE during submaximal (+1.14±0.45 °C) and maximal exercise intensity (0.68±0.57 °C) and was poorely related to V̇O2max and body composition. Energy expenditure significantly differed between both garments (+37% in PPE) and groups (P<0.05). Additionally, energy expenditure significantly correlated with body weight (r=0.84 in SPW and r=0.68 in PPE).

Conclusions: Strength training alone does not seem to have any or negligible effects on thermoregulation. Endurance training and weight management might lead to rather small improvements in heat tolerance.