Mild Hypohydration Decreases Cycling Performance in the Heat.

• Autores: Costas N. Bardis, Labros S. Sidossis, Stavros A. Kavouras, Lena Kosti, Marietta Markousi
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 45, Nº. 9, 2013, págs. 1782-1789
• Idioma: inglés
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• Dialnet Métricas: 1 Cita
• Resumen

  • AB Introduction: Hypohydration exceeding 2% of body mass decreases exercise performance. However, the effects of mild hypohydration (<2%) are not clear. Purpose: The aim of this study was to determine the effects of mild hypohydration on cycling performance during a simulated-hill circuit course in a warm environment (32.5[degrees]C +/- 0.5[degrees]C). Methods: Ten trained male cyclists (age, 30 +/- 7 yr; mass, 78.4 +/- 9.5 kg; height, 1.80 +/- 0.01 m; V[spacing dot above]O2max, 52.4 +/- 3.3 mL[middle dot]min-1[middle dot]kg-1; and Powermax, 355 +/- 29 W) performed a cycling circuit three times on a laboratory ergometer consisting of 5 km at 50% of maximum power output and 5 km at an all-out pace, followed by a 5-min rest every 5 km. Subjects started the performance test either euhydrated (EUH) or hypohydrated (HYP), by 0% +/- 0% and -1.0% +/- 0.1% of body mass, respectively. Results: Mean speed at the first, second, and third 5-km simulated-hill cycling was higher in the EUH (28.1 +/- 3.1, 27.7 +/- 3, and 27.0 +/- 3.6 km[middle dot]h-1) than that in the HYP trial (27.0 +/- 2.9, 26.1 +/- 3.7, and 25.9 +/- 3.6 km[middle dot]h-1) (P < 0.05). Mean power output at the first, second, and third 5-km simulated-hill cycling was greater in the EUH (284 +/- 55, 266 +/- 53, and 254 +/- 58 W) than that in the HYP trial (272 +/- 56, 250 +/- 61, and 240 +/- 57 W) (P < 0.05). Gastrointestinal temperature at the end of the first, second, and third 5-km simulated-hill cycling was greater in the HYP (38.3[degrees]C +/- 0.4[degrees]C, 38.4[degrees]C +/- 0.2[degrees]C, and 38.6[degrees]C +/- 0.2[degrees]C) than that in the EUH trial (38.1[degrees]C +/- 0.3[degrees]C, 38.1[degrees]C +/- 0.3, and 38.3[degrees]C +/- 0.3[degrees]C) (P < 0.05). Overall, sweat sensitivity during the circuit course was greater in the EUH (115 +/- 58 g[middle dot][degrees]C-1[middle dot]min-1) versus HYP trial (67 +/- 19 g[middle dot][degrees]C-1[middle dot]min-1) (P < 0.05). Furthermore, RPE and heart rate were similar and near maximal between trials (P > 0.05). Conclusion: The data showed that mild hypohydration decreased cycling performance, possible by inducing greater thermal and cardiovascular strain