The Effect of Heat Acclimatization, Heat Acclimation, and Intermittent Exercise on Aerobic Performance

The primary aim of this study is to determine if heat acclimation (HA)/acclimatization (HAz) improves VO2max. A secondary aim of this study is to examine whether or not any changes in VO2maxoccur during intermittent exercise heat exposures (HAM). Twenty-seven male endurance runners (mean±SD: age: 36±12 years, nude body mass: 73.03±8.97 kg, height: 178.81±6.39 cm, VO2max: 57.48±7.03 ml×kg-1×min-1) performed five VO2maxtests at various time points (baseline, test 1; post-HAz, test2; post-HA, test 3; 4 weeks of HAM, test4; 8 weeks of HAM, test5). Participants completed a summer training regimen after test 1. After summer training, each participant completed a 5-day HA protocol. Participants were randomly assigned to one of three groups for the HAM, once a week (n=9), twice a week (n=10), or not at all/control (n=8). Differences in VO2max, vVO2, and max HR for tests 1-3 were analyzed using one-way ANOVAs while tests 3-test 5 were analyzed using repeated measure ANOVAs with Bonferroni corrections post-hoc. Statistical significance was defined as p2maxdata between any of the VO2maxtests 1-3 (mean±SD: 57.92±6.8, 59.65±8.2, 59.49±7.2 ml×kg-1×min-1, p=0.363). There were no significant group or time effects for tests 3-5 (p=0.671), therefore no differences were found between experimental groups. There were significant differences in maximal heart rate (HR) between test 1-3 (mean± SD: 180 11bpm, 177± 10bpm, 175± 10bpm, p=0.006). There were significant differences in HR between test 1 and test 3 (mean± SD: 180± 11bpm vs. 175± 10bpm, p2max) following HA