Reliability of a 60-min treadmill running protocol in the heat: The journal <i>Temperature</i> toolbox

We determined the reliability of a 60-min treadmill protocol in heat when spaced >4 weeks apart, longer than test–retest duration 1 week found literature. Nine unacclimated, trained males (age: 31 ± 8 y; VO2peak: 60 6 ml∙kg−1∙min−1) undertook 15 min self-paced time-trial pre-loaded with 45 running at 70% individual ventilatory threshold (11.2 0.3 km∙h−1) 30 1°C (53 5% relative humidity). They repeated this following 40 14 and 76 26 days, pre-trial standardization diet exercise for 48 h. When considering trial as familiarization, change core temperature (∆Tcore) during first (∆2.0 0.2°C) between trials 2 3 yielded bias 95% limits agreement (LoA) −0.10 0.43°C, standard error measurement (SEM) 0.13°C intraclass correlation coefficient (ICC) 0.75, more reliable measures baseline Tcore (36.9 0.2°C; LoA: −0.23 0.90°C; SEM: 0.22°C; ICC: 0.03) (38.9 0.4°C; 0.32 1.12°C; 0.28°C; 0.15). The variation (CV) distance run was 2.1 2.0% LoA 0.001 0.253 km SEM 0.037 km. This is ~5 apart most commonly accepted limit <5% CV performance, reinforced by ΔTcore being 0.1 0.4°C.