Carbohydrate supplementation improves time-trial cycle performance during energy deficit at 4,300-m altitude
| Autor: | Paul B. Rock, K. W. Kambis, Anne L. Friedlander, S. R. Muza, Allen Cymerman, Charles S. Fulco |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Adult
Male Physiology Physical exercise Hypoxemia Time trial Animal science Altitude Double-Blind Method Physiology (medical) Dietary Carbohydrates Humans Medicine Energy deficit business.industry Effects of high altitude on humans Carbohydrate Carbohydrate supplementation Adaptation Physiological Bicycling Dietary Supplements Physical Endurance medicine.symptom Energy Metabolism business Psychomotor Performance |
| Zdroj: | Journal of Applied Physiology. 99:867-876 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/japplphysiol.00019.2005 |
| Popis: | Carbohydrate supplementation (CHOS) typically improves prolonged time-trial (TT) performance at sea level (SL). This study determined whether CHOS also improves TT performance at high altitude (ALT; 4,300 M) despite increased hypoxemia and while in negative energy balance (∼1,250 kcal/day). Two groups of fasting, fitness-matched men performed a 720-kJ cycle TT at SL and while living at ALT on days 3 (ALT3) and 10 (ALT10). Eight men drank a 10% carbohydrate solution (0.175 g/kg body wt) and eight drank a placebo (PLA; double blind) at the start of and every 15 min of the TT. Blood glucose during each TT was higher ( P < 0.05) for CHOS than for PLA. At SL, TT duration (∼59 min) and watts (∼218 or ∼61% of peak watts; %SL Wpeak) were similar for both groups. At ALT, the TT was longer for both groups ( P < 0.01) but was shorter for CHOS than for PLA on ALT3 (means ± SE: 80 ± 7 vs. 105 ± 9 min; P < 0.01) and ALT10 (77 ± 7 vs. 90 ± 5 min; P < 0.01). At ALT, %SL Wpeak was reduced ( P < 0.01) with the reduction on ALT3 being larger for PLA (to 33 ± 3%) than for CHOS (to 43 ± 2%; P < 0.05). On ALT3, O2 saturation fell similarly from 84 ± 2% at rest to 73 ± 1% during the TT for both groups ( P < 0.05), and on ALT10 O2 saturation fell more ( P < 0.02) for CHOS (91 ± 1 to 76 ± 2%) than for PLA (90 ± 1 to 81 ± 1%). %SL Wpeak and O2 saturation were inversely related during the TT for both groups at ALT ( r ≥ −0.76; P ≤ 0.03). It was concluded that, despite hypoxemia exacerbated by exercise, CHOS greatly improved TT performance at ALT in which there was a negative energy balance. |
| Databáze: | OpenAIRE |
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