title: Brief Heat Training: No Improvement of the Lactate Threshold in Mild Conditions.
abstract: OBJECTIVE
  Athletes often seek the minimum required time that might elicit a physiological or performance change. It is reasonable to suggest that heat training may improve aerobic-based performance in mild conditions. Therefore, rather than providing a traditional heat-exposure stimulus (ie, 7-10 × 60-100 min sessions), the current article details 2 studies that aimed to determine the effect of brief (≤240 min exposure) heat training on the second lactate threshold (LT2) in mild conditions.
  
  
  METHODS
  Forty-one participants completed 5 (study 1, n = 18) or 4 (study 2, n = 23) perceptually regulated treadmill exercise training sessions in 35°C and 30% relative humidity (RH) (experimental group) or 19°C and 30% RH (control group). Preincremental and postincremental exercise testing occurred in mild conditions (19°C and 30% RH). Linear mixed-effects models analyzed the change in LT2. Results Heat training did not substantially change LT2in either study 1 (+1.2%, d = 0.38, P = .248) or study 2 (+1.9%, d = 0.42, P = .163). LT2was not substantially changed in the control group in study 1 (+1.3%, d = 0.43, P = .193), but a within-group change was evident in study 2 (+2.3%, d = 1.04, P = .001).
  
  
  CONCLUSIONS
  Brief heat training was inadequate to improve the speed at LT2in mild conditions more than comparable training in mild conditions. The brief nature of the heattraining protocol did not allow adaptations to develop to the extent required to potentially confer a performance advantage in an environment that is less thermally stressful than the training conditions.
authors.forename: Samuel
authors.initials: S
authors.lastname: Chalmers
authors.forename: Adrian
authors.initials: A
authors.lastname: Esterman
authors.forename: Roger
authors.initials: R
authors.lastname: Eston
authors.forename: Kevin
authors.initials: K
authors.lastname: Norton
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D015308:Anaerobic Threshold; D054874:Athletic Performance; D015415:Biomarkers / Q000097:blood; D000072599:Cardiorespiratory Fitness; D005080:Exercise Test; D017079:Exercise Tolerance; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D064797:Physical Conditioning, Human / Q000379:methods*; D012119:Respiration; D012420:Running; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid
keywords: acclimation; hot; perceived exertion; performance; running