Performance and pacing during cycle exercise in hyperthermic and hypoxic conditions

J.D. Périard, Sebastien Racinais

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Introduction: This study examined the influence of alterations in maximal oxygen uptake (V·O2max) in mediating performance and pacing during prolonged self-paced exercise. Methods: Twelve well-trained cyclists completed a 750-kJ time trial in temperate (COOL, 18°C), hot (HOT, 35°C), and hypoxic (HYP, 18°C; FiO2, 0.145) conditions, creating models with a stable, progressively decreasing, and acutely decreased V·O2max, respectively. Results: Trial completion was faster in COOL (48.2 ± 5.7 min) compared with HOT (55.4 ± 5.0 min) and HYP (60.1 ± 6.5 min) (P < 0.001), with HOT being faster than HYP (P = 0.028). Core temperature reached 39.0°C ± 0.6°C (COOL), 39.8°C ± 0.5°C (HOT), and 38.5°C ± 0.4°C (HYP; P < 0.01). Power output during COOL was higher than HOT from 40% of work completed onward (P < 0.05) and for the entirety of HYP (P < 0.001), in which it was lower than HOT at 20%–30% (P < 0.05). Normalized power output during COOL and HYP varied by ~13% and ~16%, respectively, whereas a ~27% variation occurred in HOT. V·O2 in COOL was higher than HOT from 70% onward (P < 0.01) and higher than HYP throughout exercise (P < 0.001). Relative to baseline V·O2max (%V·O2max) in normoxia (COOL and HOT) and hypoxia (HYP), %V·O2max during HOT (78% ± 8%) was lower than COOL (84% ± 7%; P = 0.005) and HYP (87% ± 5%; P = 0.003). Conclusions: Despite an acutely reduced V·O2max and power output in HYP, pacing and %V·O2max were similar to COOL. In contrast, the progressive decrease in V·O2max and power output in HOT resulted in a more variable pacing pattern with %V·O2max decreasing throughout exercise. These data support the premise that pacing is associated with maintaining an optimal performance intensity, in conjunction with acute and progressive alterations in V·O2max
Original languageEnglish
Pages (from-to)845-853
Number of pages9
JournalMedicine and Science in Sports and Exercise
Issue number5
Publication statusPublished - 2016
Externally publishedYes


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