Exacerbated heat strain during consecutive days of repeated exercise sessions in heat

Pryor, Riana R.; Pryor, J. Luke; Vandermark, Lesley W.; Adams, Elizabeth L.; Brodeur, Rachel M.; Armstrong, Lawrence E.; Lee, Elaine C.; Maresh, Carl M.; Anderson, Jeffrey M.; Casa, Douglas J.

doi:10.1016/j.jsams.2019.06.003

Cited by 13 publications

(22 citation statements)

References 27 publications

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“…Their HA protocol consisted of 100 min walking in a warm environment while we used a hyperthermia-clamped protocol and tested at a greater exercise intensity in a much hotter environment. Despite any renal function benefits potentially gained during HA and possible reduced risk of AKI, the oppressive testing environment and high-intensity work in the current study, which is known to lead to exacerbated heat strain on the second day of two consecutive days of work [34,41], may have overshadowed these benefits. Additionally, a more traditional HA period of 10-14 days may be needed to mitigate the rise in clinical biomarkers of AKI and reduce AKI risk.…”

Section: Discussionmentioning

confidence: 80%

“…On each of these days, the exercise protocol was comprised of two, two-hour interval aerobic treadmill exercise sessions, separated by two hours of rest in a temperate environment. Intensities rotated among resting, walking at 4.83 km•h −1 , jogging at 60% VO 2max , and running at 80% VO 2max to mimic intensities of Division I National Collegiate Athletic Association football preseason and are described elsewhere [34]. Subjects drank water ad libitum throughout all testing sessions, with the volume of water that participants consumed recorded.…”

Section: Exercise Protocolmentioning

confidence: 99%

“…On day 2, participants completed a two-hour exercise session consisting of the same exercise intensities as days 1 and 6. This was completed as a part of a larger study, the results of which have been published previously [34]. On days 3-5, participants completed 90 min of cycling and/or treadmill exercise.…”

Section: Exercise Protocolmentioning

confidence: 99%

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Acute Kidney Injury Biomarker Responses to Short-Term Heat Acclimation

Pryor

Vandermark

et al. 2020

IJERPH

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The combination of hyperthermia, dehydration, and strenuous exercise can result in severe reductions in kidney function, potentially leading to acute kidney injury (AKI). We sought to determine whether six days of heat acclimation (HA) mitigates the rise in clinical biomarkers of AKI during strenuous exercise in the heat. Twenty men completed two consecutive 2 h bouts of high-intensity exercise in either hot (n = 12, 40 °C, 40% relative humidity) or mild (n = 8, 24 °C, 21% relative humidity) environments before (PreHA) and after (PostHA) 4 days of 90–120 min of exercise per day in a hot or mild environment. Increased clinical biomarkers of AKI (CLINICAL) was defined as a serum creatinine increase ≥0.3 mg·dL−1 or estimated glomerular filtration rate (eGFR) reduction >25%. Creatinine similarly increased in the hot environment PreHA (0.35 ± 0.23 mg·dL−1) and PostHA (0.39 ± 0.20 mg·dL−1), with greater increases than the mild environment at both time points (0.11 ± 0.07 mg·dL−1, 0.08 ± 0.06 mg·dL−1, p ≤ 0.001), respectively. CLINICAL occurred in the hot environment PreHA (n = 9, 75%), with fewer participants with CLINICAL PostHA (n = 7, 58%, p = 0.007), and no participants in the mild environment with CLINICAL at either time point. Percent change in plasma volume was predictive of changes in serum creatinine PostHA and percent changes in eGFR both PreHA and PostHA. HA did not mitigate reductions in eGFR nor increases in serum creatinine during high-intensity exercise in the heat, although the number of participants with CLINICAL was reduced PostHA.

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Section: Discussionmentioning

confidence: 80%

Section: Exercise Protocolmentioning

confidence: 99%

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Acute Kidney Injury Biomarker Responses to Short-Term Heat Acclimation

Pryor

Vandermark

et al. 2020

IJERPH

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“…30 Repetitive heat exposures within a day (ie, multiple practices in a single day) do not appear to expedite the process; thus, single daily exposures (ie, 1 practice per day) during 2 full weeks of heat exposure is the safest effective strategy. 31 Further, multiple heat exposures in a given day (eg, 2 practice sessions per day) may be detrimental to an athlete's safety based on evidence 32 of greater thermal strain during a second exercise session compared with the first in a given day.…”

Section: Time Course Of Heat Acclimatization and Decaymentioning

confidence: 99%

Roundtable on Preseason Heat Safety in Secondary School Athletics: Heat Acclimatization

Adams

Hosokawa

Casa

et al. 2021

Journal of Athletic Training

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Objective To provide best-practice recommendations for developing and implementing heat-acclimatization strategies in secondary school athletics. Data Sources An extensive literature review on topics related to heat acclimatization and heat acclimation was conducted by a group of content experts. Using the Delphi method, action-oriented recommendations were developed. Conclusions A period of heat acclimatization consisting of ≥14 consecutive days should be implemented at the start of fall preseason training or practices for all secondary school athletes to mitigate the risk of exertional heat illness. The heat-acclimatization guidelines should outline specific actions for secondary school athletics personnel to use, including the duration of training, the number of training sessions permitted per day, and adequate rest periods in a cool environment. Further, these guidelines should include sport-specific and athlete-specific recommendations, such as phasing in protective equipment and reintroducing heat acclimatization after periods of inactivity. Heat-acclimatization guidelines should be clearly detailed in the secondary school's policy and procedures manual and disseminated to all stakeholders. Heat-acclimatization guidelines, when used in conjunction with current best practices surrounding the prevention, management, and care of secondary school student-athletes with exertional heat stroke, will optimize their health and safety.

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“…16 Even 120 min of rest between moderate-high intensity exercise-heat exposures resulted in higher core temperatures and HR during a subsequent identical work session. 17 Of particular note, only 81% of the second session could be completed before work cessation due to volitional fatigue, symptoms of heat illness, or a high core temperature. 17 To combat this exacerbated heat strain, mitigation strategies such as heat acclimation have been proposed as a potential solution.…”

Section: Introductionmentioning

confidence: 99%

Short term heat acclimation reduces heat strain during a first, but not second, consecutive exercise-heat exposure

Pryor

Pryor²,

Vandermark³

et al. 2021

Journal of Science and Medicine in Sport

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Objectives: Determine whether five days of heat acclimation reduces cardiovascular and thermoregulatory strain during consecutive exercise-heat exposures on the sixth day in the heat. Design: Pair-matched randomized control trial. Methods: Twenty-four males completed two, 120 min exercise sessions (Session 1, Session 2) in a single day before (Day 1) and after (Day 6) four additional days of exercise in either hot (HOT: 40 • C, 40% relative humidity, n = 16) or temperate (CON: 23 • C, 25% relative humidity, n = 8) environments. A mixedmethods heat acclimation approach was implemented. Day 2 consisted of 120 min of moderate-high intensity treadmill exercise. Days 3-5 consisted of 90 min of moderate-high intensity exercise, with HOT completing this in a hyperthermia clamped manner at rectal temperature ≥38.5 • C, and CON < 38.5 • C. Results: Session 1 end of exercise rectal temperature and heart rate were lower on Day 6 compared to Day 1 for HOT (p = 0.012, p = 0.003) but not CON (p = 0.152, p = 0.437). Session 2 end of exercise rectal temperature was not different between days for HOT (p = 0.104) or CON (p = 0.275). Session 2 end of exercise heart rate was lower on Day 6 compared to Day 1 for HOT (p = 0.004) and CON (p = 0.039). Session 1 sweat sensitivity was greater on Day 6 compared to Day 1 for HOT (p = 0.039) but not CON (p = 0.257). Sweat rate was unchanged for HOT and CON between days during Session 1 (p = 0.184, p = 0.962) and Session 2 (p = 0.051, p = 0.793), respectively. Conclusions: Five days of heat acclimation reduced cardiovascular strain but not thermoregulatory strain during the second, consecutive exercise-heat exposure. ClinicalTrials.gov Identifier: NCT04053465.

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Exacerbated heat strain during consecutive days of repeated exercise sessions in heat

Cited by 13 publications

References 27 publications

Acute Kidney Injury Biomarker Responses to Short-Term Heat Acclimation

Acute Kidney Injury Biomarker Responses to Short-Term Heat Acclimation

Roundtable on Preseason Heat Safety in Secondary School Athletics: Heat Acclimatization

Short term heat acclimation reduces heat strain during a first, but not second, consecutive exercise-heat exposure

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