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Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation.
Int J Sports Physiol Perform 2019; 14(8):1058-1065IJ

Abstract

PURPOSE

To investigate the effects of short-term, high-intensity interval-training (HIIT) heat acclimation (HA).

METHODS

Male cyclists/triathletes were assigned into either an HA (n = 13) or a comparison (COMP, n = 10) group. HA completed 3 cycling heat stress tests (HSTs) to exhaustion (60% Wmax; HST1, pre-HA; HST2, post-HA; HST3, 7 d post-HA). HA consisted of 30-min bouts of HIIT cycling (6 min at 50% Wmax, then 12 × 1-min 100%-Wmax bouts with 1-min rests between bouts) on 5 consecutive days. COMP completed HST1 and HST2 only. HST and HA trials were conducted in 35°C/50% relative humidity. Cycling capacity and physiological and perceptual data were recorded.

RESULTS

Cycling capacity was impaired after HIIT HA (77.2 [34.2] min vs 56.2 [24.4] min, P = .03) and did not return to baseline after 7 d of no HA (59.2 [37.4] min). Capacity in HST1 and HST2 was similar in COMP (43.5 [8.3] min vs 46.8 [15.7] min, P = .54). HIIT HA lowered resting rectal (37.0°C [0.3°C] vs 36.8°C [0.2°C], P = .05) and body temperature (36.0°C [0.3°C] vs 35.8°C [0.3°C], P = .03) in HST2 compared with HST1 and lowered mean skin temperature (35.4°C [0.5°C] vs 35.1°C [0.3°C], P = .02) and perceived strain on day 5 compared with day 1 of HA. All other data were unaffected.

CONCLUSIONS

Cycling capacity was impaired in the heat after 5 d of consecutive HIIT HA despite some heat adaptation. Based on data, this approach is not recommended for athletes preparing to compete in the heat; however, it is possible that it may be beneficial if a state of overreaching is avoided.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30702375

Citation

Reeve, Thomas, et al. "Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation." International Journal of Sports Physiology and Performance, vol. 14, no. 8, 2019, pp. 1058-1065.
Reeve T, Gordon R, Laursen PB, et al. Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation. Int J Sports Physiol Perform. 2019;14(8):1058-1065.
Reeve, T., Gordon, R., Laursen, P. B., Lee, J. K. W., & Tyler, C. J. (2019). Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation. International Journal of Sports Physiology and Performance, 14(8), pp. 1058-1065. doi:10.1123/ijspp.2018-0537.
Reeve T, et al. Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation. Int J Sports Physiol Perform. 2019 Sep 1;14(8):1058-1065. PubMed PMID: 30702375.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Impairment of Cycling Capacity in the Heat in Well-Trained Endurance Athletes After High-Intensity Short-Term Heat Acclimation. AU - Reeve,Thomas, AU - Gordon,Ralph, AU - Laursen,Paul B, AU - Lee,Jason K W, AU - Tyler,Christopher J, PY - 2018/07/16/received PY - 2018/12/19/revised PY - 2019/01/03/accepted PY - 2019/2/1/pubmed PY - 2019/9/20/medline PY - 2019/2/1/entrez KW - acclimatization KW - heat adaptation KW - high-intensity interval training KW - hyperthermia KW - overreaching SP - 1058 EP - 1065 JF - International journal of sports physiology and performance JO - Int J Sports Physiol Perform VL - 14 IS - 8 N2 - PURPOSE: To investigate the effects of short-term, high-intensity interval-training (HIIT) heat acclimation (HA). METHODS: Male cyclists/triathletes were assigned into either an HA (n = 13) or a comparison (COMP, n = 10) group. HA completed 3 cycling heat stress tests (HSTs) to exhaustion (60% Wmax; HST1, pre-HA; HST2, post-HA; HST3, 7 d post-HA). HA consisted of 30-min bouts of HIIT cycling (6 min at 50% Wmax, then 12 × 1-min 100%-Wmax bouts with 1-min rests between bouts) on 5 consecutive days. COMP completed HST1 and HST2 only. HST and HA trials were conducted in 35°C/50% relative humidity. Cycling capacity and physiological and perceptual data were recorded. RESULTS: Cycling capacity was impaired after HIIT HA (77.2 [34.2] min vs 56.2 [24.4] min, P = .03) and did not return to baseline after 7 d of no HA (59.2 [37.4] min). Capacity in HST1 and HST2 was similar in COMP (43.5 [8.3] min vs 46.8 [15.7] min, P = .54). HIIT HA lowered resting rectal (37.0°C [0.3°C] vs 36.8°C [0.2°C], P = .05) and body temperature (36.0°C [0.3°C] vs 35.8°C [0.3°C], P = .03) in HST2 compared with HST1 and lowered mean skin temperature (35.4°C [0.5°C] vs 35.1°C [0.3°C], P = .02) and perceived strain on day 5 compared with day 1 of HA. All other data were unaffected. CONCLUSIONS: Cycling capacity was impaired in the heat after 5 d of consecutive HIIT HA despite some heat adaptation. Based on data, this approach is not recommended for athletes preparing to compete in the heat; however, it is possible that it may be beneficial if a state of overreaching is avoided. SN - 1555-0273 UR - https://www.unboundmedicine.com/medline/citation/30702375/Impairment_of_Cycling_Capacity_in_the_Heat_in_Well_Trained_Endurance_Athletes_After_High_Intensity_Short_Term_Heat_Acclimation_ L2 - https://journals.humankinetics.com/doi/10.1123/ijspp.2018-0537 DB - PRIME DP - Unbound Medicine ER -