Can ten days of heat acclimation training improve temperate-condition rowing performance in national-level rowers?

PLOS ONE RESEARCH ARTICLE Can ten days of heat acclimation training improve temperate-condition rowing performance in national-level rowers? Calvin P. Philp ID1*, Nathan W. Pitchford ID1, Denis C. Visentin1, Cecilia M. Kitic2, James W. Fell1, Martin Buchheit3,4,5,6, Christopher T. Minson7, John R. Gregory8, Greig Watson1 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Sport Performance Optimisation Research Team, School of Health Sciences, University of Tasmania, Launceston, Tasmania, Australia, 2 School of Health, Medical and Applied Sciences, Central Queensland University, Brisbane, Queensland, Australia, 3 French National Institute of Sport (INSEP), Laboratory of Sport, Expertise and Performance (EA 7370), Paris, France, 4 Institute for Health & Sport, Victoria University, Melbourne, VIC, Australia, 5 HIIT Science, Revelstoke, BC, Canada, 6 Kitman Labs, Performance Research Intelligence Initiative, Dublin, Ireland, 7 Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America, 8 Sports Performance Unit, Tasmanian Institute of Sport, Launceston, Tasmania, Australia * OPEN ACCESS Citation: Philp CP, Pitchford NW, Visentin DC, Kitic CM, Fell JW, Buchheit M, et al. (2022) Can ten days of heat acclimation training improve temperatecondition rowing performance in national-level rowers? PLoS ONE 17(9): e0273909. https://doi. org/10.1371/journal.pone.0273909 Editor: Zulkarnain Jaafar, Universiti Malaya, MALAYSIA Received: April 12, 2022 Accepted: August 18, 2022 Published: September 1, 2022 Copyright: © 2022 Philp et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Unfortunately as data sharing was not written into the ethics approval for this study it cannot be made publicly available at this time, however, the Tasmanian Health and Medical Human Research Ethics Committee can be contacted at the following address for access to the data: . Abstract This study investigated whether heat acclimation (HA) could improve rowing performance in temperate conditions in national-level rowers. Using a parallel-group design, eleven rowers (3 female, 8 male, age: 21±3 years, height: 182.3±6.8cm, mass: 79.2±9.0kg, V_ O : 61.4±5.1ml�kg�min-1) completed either a HA intervention (HEAT, n = 5) or acted 2peak as controls (CON, n = 6). The intervention replaced usual cross-training sessions and consisted of an hour of submaximal cycling or rowing ergometry in either 34±0˚C for HEAT or 14±1˚C for CON daily over two five-day blocks (10 sessions total), separated by 72h. Participants performed the ‘10+4’ test that consists of 10-min submaximal rowing and a 4-min time-trial (TT) in temperate conditions (20±0˚C) before and after the intervention. Heat acclimation following the 10-session intervention was evidenced by large significant (p<0.05) decreases in maximum tympanic temperature (d = -1.68) and rate of perceived exertion (RPE) (d = -2.26), and a large significant increase in sweat loss (d = 0.91). Large non-significant (p>0.05) decreases were seen in average tympanic temperature (d = -3.08) and average heart rate (d = -1.53) in HEAT from session 2 to session 10 of the intervention. Furthermore, a large significant increase was seen in plasma volume (d = 3.74), with large significant decreases in haemoglobin concentration (d = -1.78) and hematocrit (d = -12.9). Following the intervention, large non-significant increases in respiratory exchange ratio (d = 0.87) and blood lactate (d = 1.40) as well as a large non-significant decrease in RPE (d = -1.23) were seen in HEAT during the 10-min submaximal rowing. A large significant decrease in peak heart rate (d = -2.27), as well as a large nonsignificant decrease in relative V_ O (d = -0.90) and large non-significant increases in 2peak Funding: The author(s) received no specific funding for this work. respiratory exchange ratio (d = 1.18), blood lactate concentration (d = 1.25) and power output (d = 0.96) were seen in HEAT during the 4-min TT. This study suggests that a 10- Competing interests: The authors have declared that no competing interests exist. PLOS ONE | https://doi.org/10.1371/journal.pone.0273909 September 1, 2022 1 / 17 PLOS ONE Heat acclimation improves rowing performance session HA intervention may elicit HA in national-level rowers, with potential to improve 4min TT performance in temperate conditions. Introduction Heat acclimation (HA) is the repeated exposure to high environmental temperatures to cause favourable physiological and perceptual adaptations that may not be achievable when exercising in cool and temperate conditions alone. Adaptions such as plasma volume (PV) expansion, lower heart rate (HR) [1], decreased rating of perceived exertion (RPE) [2] and reduced core temperature during exercise [2] are signs of HA thought to enhance exercise economy [3,4], increase maximal oxygen uptake (V_ O2max ) [5,6], and increase power at lactate threshold [5]. All of which may improve athletic performance in both hot [7,8] and cool environments [5,6,9]. Rowing athletes appear to be a cohort that could benefit from HA, as V_ O2max [10–12], power output at V_ O2max [10,11] and power output at a blood lactate concentration of 4mmol�l1 [10] are all favourable adaptions of HA that are highly correlated with rowing performance. However, to date, literature surrounding the effectiveness of HA on rowing performance is scarce, with to the authors’ knowledge, only one study having examined the impact of HA directly on rowing performance [8]. Garrett and colleagues [8] found that HA (90 min�d-1 for 5 days) caused a 4.5% plasma volume (PV) expansion measured at rest, lower HR (-14 bpm) and rectal temperature (-0.3˚C) at the completion of 20 minutes of submaximal rowing, along with a quicker time to complete 2000m (-4s, -1.5%) in hot conditions (35˚C). Garrett et al. [8] suggested the PV expansion led to lower HR and core temperature, and improved cardiovascular stability, during the 2000m row, which resulted in greater power output and faster times. Although the findings of Garrett et al. [8] are promising, not all rowing events are held in hot environments. For example, prestigious events such as the Oxford and Cambridge boat race and the Head of the Charles regatta are held in spring and autumn months when average maximum daily temperatures are commonly 12–19˚C [13,14]. Furthermore, Australian national rowing team laboratory performance tests are completed in temperate conditions (20˚C). Therefore, the effect of HA on rowing performance in cool or temperate climates warrants investigation in order to benefit well-trained rowing athletes looking to improve performance in either temperate-condition competition or selection criteria events. The topic of HA as an ergoge (...truncated)