Tags

Type your tag names separated by a space and hit enter

Influence of hydration status on thermoregulation and cycling hill climbing.
Med Sci Sports Exerc. 2007 Feb; 39(2):323-9.MS

Abstract

PURPOSE

Although dehydration can impair endurance performance, a reduced body mass may benefit uphill cycling by increasing the power-to-mass ratio. This study examined the effects of a reduction in body mass attributable to unreplaced sweat losses on simulated cycling hill-climbing performance in the heat.

METHODS

Eight well-trained male cyclists (mean +/- SD: 28.4 +/- 5.7 yr; 71.0 +/- 5.9 kg; 176.7 +/- 4.7 cm; VO2peak: 66.2 +/- 5.8 mL x kg(-1) x min(-1)) completed a maximal graded cycling test on a stationary ergometer to determine maximal aerobic power (MAP). In a randomized crossover design, cyclists performed a 2-h ride at 53% MAP on a stationary ergometer, immediately followed by a cycling hill-climb time-to-exhaustion trial (88% MAP) on their own bicycle on an inclined treadmill (8%) at approximately 30 degrees C. During the 2-h ride, they consumed either 2.4 L of a 7% carbohydrate (CHO) drink (HIGH) or 0.4 L of water (LOW) with sport gels to match for CHO content.

RESULTS

After the 2-h ride and before the hill climb, drinking strategies influenced body mass (LOW -2.5 +/- 0.5% vs HIGH 0.3 +/- 0.4%; P < 0.001), HR (LOW 158 +/- 15 vs HIGH 146 +/- 15 bpm; P = 0.03), and rectal temperature (T(re): LOW 38.9 +/- 0.2 vs HIGH 38.3 +/- 0.2 degrees C; P = 0.001). Despite being approximately 1.9 kg lighter, time to exhaustion was significantly reduced by 28.6 +/- 13.8% in the LOW treatment (LOW 13.9 +/- 5.5 vs HIGH 19.5 +/- 6.0 min, P = 0.002), as was the power output for a fixed speed (LOW 308 +/- 28 vs HIGH 313 +/- 28 W, P = 0.003). At exhaustion, T(re) was higher in the LOW treatment (39.5 vs HIGH 39.1 degrees C; P < 0.001), yet peak HR, blood lactate, and glucose were similar.

CONCLUSION

Exercise-induced dehydration in a warm environment is detrimental to laboratory cycling hill-climbing performance despite reducing the power output required for a given speed.

Authors+Show Affiliations

Department of Physiology, Australian Institute of Sport, Canberra, Australia. tammie.ebert@ausport.gov.auNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17277597

Citation

Ebert, Tammie R., et al. "Influence of Hydration Status On Thermoregulation and Cycling Hill Climbing." Medicine and Science in Sports and Exercise, vol. 39, no. 2, 2007, pp. 323-9.
Ebert TR, Martin DT, Bullock N, et al. Influence of hydration status on thermoregulation and cycling hill climbing. Med Sci Sports Exerc. 2007;39(2):323-9.
Ebert, T. R., Martin, D. T., Bullock, N., Mujika, I., Quod, M. J., Farthing, L. A., Burke, L. M., & Withers, R. T. (2007). Influence of hydration status on thermoregulation and cycling hill climbing. Medicine and Science in Sports and Exercise, 39(2), 323-9.
Ebert TR, et al. Influence of Hydration Status On Thermoregulation and Cycling Hill Climbing. Med Sci Sports Exerc. 2007;39(2):323-9. PubMed PMID: 17277597.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Influence of hydration status on thermoregulation and cycling hill climbing. AU - Ebert,Tammie R, AU - Martin,David T, AU - Bullock,Nicola, AU - Mujika,Iñigo, AU - Quod,Marc J, AU - Farthing,Lesley A, AU - Burke,Louise M, AU - Withers,Robert T, PY - 2007/2/6/pubmed PY - 2007/4/11/medline PY - 2007/2/6/entrez SP - 323 EP - 9 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 39 IS - 2 N2 - PURPOSE: Although dehydration can impair endurance performance, a reduced body mass may benefit uphill cycling by increasing the power-to-mass ratio. This study examined the effects of a reduction in body mass attributable to unreplaced sweat losses on simulated cycling hill-climbing performance in the heat. METHODS: Eight well-trained male cyclists (mean +/- SD: 28.4 +/- 5.7 yr; 71.0 +/- 5.9 kg; 176.7 +/- 4.7 cm; VO2peak: 66.2 +/- 5.8 mL x kg(-1) x min(-1)) completed a maximal graded cycling test on a stationary ergometer to determine maximal aerobic power (MAP). In a randomized crossover design, cyclists performed a 2-h ride at 53% MAP on a stationary ergometer, immediately followed by a cycling hill-climb time-to-exhaustion trial (88% MAP) on their own bicycle on an inclined treadmill (8%) at approximately 30 degrees C. During the 2-h ride, they consumed either 2.4 L of a 7% carbohydrate (CHO) drink (HIGH) or 0.4 L of water (LOW) with sport gels to match for CHO content. RESULTS: After the 2-h ride and before the hill climb, drinking strategies influenced body mass (LOW -2.5 +/- 0.5% vs HIGH 0.3 +/- 0.4%; P < 0.001), HR (LOW 158 +/- 15 vs HIGH 146 +/- 15 bpm; P = 0.03), and rectal temperature (T(re): LOW 38.9 +/- 0.2 vs HIGH 38.3 +/- 0.2 degrees C; P = 0.001). Despite being approximately 1.9 kg lighter, time to exhaustion was significantly reduced by 28.6 +/- 13.8% in the LOW treatment (LOW 13.9 +/- 5.5 vs HIGH 19.5 +/- 6.0 min, P = 0.002), as was the power output for a fixed speed (LOW 308 +/- 28 vs HIGH 313 +/- 28 W, P = 0.003). At exhaustion, T(re) was higher in the LOW treatment (39.5 vs HIGH 39.1 degrees C; P < 0.001), yet peak HR, blood lactate, and glucose were similar. CONCLUSION: Exercise-induced dehydration in a warm environment is detrimental to laboratory cycling hill-climbing performance despite reducing the power output required for a given speed. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/17277597/Influence_of_hydration_status_on_thermoregulation_and_cycling_hill_climbing_ L2 - http://dx.doi.org/10.1249/01.mss.0000247000.86847.de DB - PRIME DP - Unbound Medicine ER -