A Warm Environment Reduces Exogenous Glucose Oxidation and Endurance Performance during Cycling with Facing Airflow
Kirsty M. Reynolds, Mark P. Funnell, Adam J. Collins, Stephen A. Mears, Jamie N. Pugh, Lewis J. JamesABSTRACT
Exercise in warm environments increases thermal/cardiovascular strain and decreases gastrointestinal (GI) integrity and endurance performance. However, laboratory-based studies have provided little to/no facing airflow, potentially exacerbating these effects, particularly for cycling, where convective cooling may be a major contributor to thermal balance.
Purpose
This study investigated the effect of cycling in a warm vs temperate environment with sufficient facing airflow on exogenous glucose use, performance, and GI responses.
Methods
Ten trained male cyclists/triathletes (36 ± 6 y; 55 ± 6 mL/kg/min) completed
Results
Average 40-120 min (TEMP 0.56 ± 0.13 g/min; WARM 0.48 ± 0.12 g/min; 15%;
Conclusions
These data demonstrate that ability to use glucose provided in drinks was impaired during prolonged cycling in WARM. WARM ambient conditions impaired laboratory-based cycling performance, even with facing airflow approximating outdoor conditions, likely via impairments of thermoregulatory, cardiovascular, and metabolic function.