Effects of a New Evaporative Cooling Solution During Rowing in a Warm Environment

Transcription

1 TECHNICAL REPORT International Journal of Sports Physiology and Performance, 2010, 5, Human Kinetics, Inc. Effects of a New Evaporative Cooling Solution During Rowing in a Warm Environment Iñigo Mujika, Rafa González De Txabarri, and David Pyne Energicer is a new solution which purportedly increases evaporative cooling during exercise in the heat. Purpose: To evaluate the effect of Energicer on performance during indoor rowing in a warm environment. Methods: Eighteen highly trained rowers (age 23.3 ± 6.7 y, height ± 6.0 cm, mass 76.7 ± 5.0 kg, peak aerobic power (PAP) ± 24.3 W; mean ± SD) performed two indoor rowing trials at 25.0 C and 65.0% relative humidity. Each trial consisted of 10 min at 55% PAP, 5 min of rest, 10 min at 70% PAP, 10 min of rest, and 2000 m time trial. Subjects were randomly assigned to an experimental (COOL) or a placebo (PLA) condition, using a double-blind, crossover design. During COOL, subjects wore sweatbands soaked in Energicer on both forearms; during PLA, they wore identical sweatbands soaked in cool water. Physiological measures and rowing performance were analyzed in a post-test-only crossover design. Magnitude of the difference between treatments was interpreted using the Cohen s effect statistic. Results: No substantial differences were observed in heart rate, blood lactate and RPE between treatments during the submaximal row (COOL 163 ± 10 bpm, 4.3 ± 1.0 mm, 14.5 ± 1.8; PLA 165 ± 11 bpm, 4.8 ± 1.4 mm, 14.6 ± 1.6) and the time trial (COOL 179 ± 9 bpm, 10.7 ± 2.3 mm, 20 ± 0; PLA 179 ± 10 bpm, 11.1 ± 2.2 mm, 20 ± 0). Time (419 ± 11 vs 420 ± 12 s), mean power (305 ± 24 vs 304 ± 26 W), sweat loss (1013 ± 186 vs 981 ± 161 ml) and pacing strategy during the time trial were similar in COOL and PLA. The magnitude of differences between treatments was trivial for all measured variables. Conclusion: Energicer failed to provide a substantial benefit during indoor rowing in a warm environment. Whether Energicer is beneficial during more prolonged exercise and/or under more stressful environmental conditions remains to be elucidated. Keywords: Energicer, performance, heat stress, hydration High ambient temperature and humidity are associated with reduced capacity for endurance exercise. Various cooling strategies have been developed to limit the negative impact of heat stress on performance. Most of these strategies, however, Iñigo Mujika is with USP Araba Sport Clinic, Vitoria-Gasteiz, Basque Country, and with the Department of Physiology, Faculty of Medicine and Odontology, University of the Basque Country. Rafa González De Txabarri is with Orio Arraunketa Elkartea, Orio, Basque Country. David Pyne is with the Department of Physiology, Australian Institute of Sport, Canberra, Australia. 412

2 Energicer and Rowing Performance 413 consist of precooling interventions to reduce an athlete s core temperature before competition. 1 Recently, an alcohol and menthol based liquid solution has been marketed which purportedly provides a high rate of evaporative cooling by wearing sweatbands soaked in it during exercise in the heat. The purpose of this investigation was to evaluate the effect of the new Energicer evaporative cooling solution on submaximal and maximal performance during indoor rowing in a warm environment. Methods Eighteen highly trained fixed-seat traditional rowers (age 23.3 ± 6.7 y, height ± 6.0 cm, mass 76.7 ± 5.0 kg, peak aerobic power (PAP) ± 24.3 W; mean ± SD) performed two indoor rowing trials separated by 48 h in a warm environment (ambient temperature 25.0 C, relative humidity 65.0%). Training load was reduced and identical for all subjects the day before each testing session. Each trial consisted of 10 min of warm-up at 55% PAP, 5 min of rest, 10 min of submaximal rowing at 70% PAP, 10 min of rest and finally a 2000 m all-out time trial. Rowing trials were performed on a wind-braked rowing ergometer (Concept 2, Model D, Morrisville, VT, USA) modified with a static seat, legs in semiflexion at a length adapted to each rower and a drag factor of Subjects were randomly assigned to an experimental (COOL) or a placebo (PLA) condition, using a double-blind, crossover design. During COOL, subjects wore sweatbands soaked in Energicer evaporative cooling solution (Liquid Ice CosMedicals AG, Unterägeri, Switzerland) on both forearms for the duration of the trial (ie, beginning of warm-up to end of time trial); during PLA, they wore the same sweatbands soaked in cool water. Nude body mass (toweled dry) was measured on a digital scale (Seca 877, Hamburg, Germany) before and after the rowing trials, and fluid intake during the trials was measured with a digital scale (Soehnle 66100, Nassau, Germany). Heart rate was continuously monitored throughout the trials (Suunto Team Pack Pro, Vantaa, Finland), and blood lactate was measured from a 5 μl capillary blood sample obtained from the ear lobe (Lactate Pro, Arkray Factory Inc., Shiga, Japan). Descriptive statistics were mean and standard deviation. Rowing performance and physiological measures were analyzed in a post-test-only crossover design. 3 Data were log-transformed to reduce the nonuniformity of error and then backtransformed to obtain the percentage difference in the mean between the treatment conditions. Precision of estimation was indicated with 90% confidence limits. Magnitude of the difference between conditions was interpreted using Cohen s effect statistic where <0.2, trivial; 0.2 to 0.6, small; 0.6 to 1.2, moderate; 1.2 to 2.0, large; and >2.0, very large. Statistical significance was accepted at P <.05. Results No substantial differences were observed in heart rate, blood lactate, RPE and mean power between treatments during the warm-up and the submaximal row (Table 1). In the 2000 m time trial, no substantial differences were evident between COOL and PLA in any of the measured variables. Performance time, mean power, mean stroke rate and total sweat loss were similar between trials. Pacing strategy during the time trial, as assessed by mean power and time in each 500 m split (Table 2),

3 Table 1 Difference in performance and physiological variables with the use of Energicer sweatbands during the rowing protocol Measure Energicer Placebo Difference (Δ% ± 90%CL) P-value Effect size Warm-up Mean heart rate (bpm) 147 ± ± ± Blood lactate (mm) 2.1 ± ± ± RPE 8.6 ± ± ± Mean power (W) 182 ± ± ± Submaximal row Mean heart rate (bpm) 163 ± ± ± Blood lactate (mm) 4.3 ± ± ± RPE 14.5 ± ± ± Mean power (W) 226 ± ± ± m time trial Mean heart rate (bpm) 179 ± ± ± min blood lactate (mm) 9.3 ± ± ± min blood lactate (mm) 10.7 ± ± ± Mean power (W) 308 ± ± ± Final time (s) 418 ± ± ± Mean stroke rate 42 ± 2 41 ± ± Total sweat loss (ml) 1009 ± ± ± Note. Effect size: <0.2 trivial, small, moderate, large, >2.0 very large. RPE = rating of perceived exertion. 414

4 Table 2 Difference in pacing strategy with use of Energicer sweatbands during the 2000 m time trial Measure Energicer Placebo Difference (Δ% ± 90%CL) P-value Effect size 1st 500 m Mean power (W) 329 ± ± ± Time (s) 103 ± ± ± nd 500 m Mean power (W) 297 ± ± ± Time (s) 106 ± ± ± rd 500 m Mean power (W) 292 ± ± ± Time (s) 106 ± ± ± th 500 m Mean power (W) 304 ± ± ± Time (s) 105 ± ± ± Note. Effect size: <0.2 trivial, small, moderate, large, >2.0 very large. 415

5 416 Mujika, González De Txabarri, and Pyne did not differ between trials. The magnitude of differences between treatments was trivial for all measured variables. Discussion The sweat bands soaked in Energicer and worn continuously for approximately 42 min, including a 10-min warm-up, a 10-min submaximal bout, and then a maximal effort 2000 m time trial indoors on a rowing ergometer, did not have a substantial effect on physiological or performance measures. These trials were conducted in moderate environmental conditions (25 C and 65% RH). The exercise protocol was relatively short in duration (approx. 27 min in total), and the environmental conditions relatively mild in comparison with hotter and more humid conditions often experienced during the summer training and competitive season. These results do not conclusively exclude the possibility that over a longer exercise duration and/ or higher ambient temperatures, this product could provide measureable benefits that might aid training and competitive performance by increasing heat removal rate or reducing perceptions of thermal strain. However, it appears there are no substantial physiological nor performance benefits of the Energicer solution in short-term exercise in moderate environmental conditions. Conclusion Energicer evaporative cooling solution failed to provide a substantial physiological or performance benefit during short-term submaximal and maximal indoor rowing in a warm environment. Whether this solution is beneficial during more prolonged exercise and/or under more stressful environmental conditions remains to be elucidated. Acknowledgments The authors would like to thank the rowers and coaching staff of Orio Arraunketa Elkartea for their enthusiasm and cooperation throughout the study. References 1. Quod MJ, Martin DT, Laursen PB. Cooling athletes before competition in the heat. Comparison of techniques and practical considerations. Sports Med. 2006;36: Izquierdo-Gabarren M, González de Txabarri Expósito R, Sáez Sáez de Villarreal E, Izquierdo M. Physiological factors to predict on traditional rowing performance. Eur J Appl Physiol. 2010;108: Hopkins WG. Spreadsheets for analysis of controlled trials with adjustment for a predictor. Sportscience. 2006;10:1 5.