Effect of Repeated Sodium Phosphate Loading on Cycling Time-Trial Performance and VO2peak
- Autores: Cameron P. Brewer, Brian T. Dawson, Karen E. Wallman, Kym J. Guelfi
- Localización: International journal of sport nutrition and exercise metabolism, ISSN 1526-484X, ISSN-e 1543-2742, Vol. 23, Nº. 2, 2013, págs. 187-194
- Idioma: inglés
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Resumen
Research into supplementation with sodium phosphate has not investigated the effects of a repeated supplementation phase. Therefore, this study examined the potential additive effects of repeated sodium phosphate (SP) supplementation on cycling time-trial performance and peak oxygen uptake (VO2peak). Trained male cyclists (N = 9, M ± SD VO2peak = 65.2 ± 4.8 ml · kg�1 · min�1) completed baseline 1,000-kJ time-trial and VO2peak tests separated by 48 hr, then ingested either 50 mg · kg fat-free mass�1 · d�1 of tribasic SP or a combined glucose and NaCl placebo for 6 d before performing these tests again. A 14-d washout period separated the end of one loading phase and the start of the next, with 2 SP and 1 placebo phase completed in a counterbalanced order. Although time-trial performance (55.3�56.5 min) was shorter in SP1 and SP2 (~60�70 s), effect sizes and smallest-worthwhile-change values did not differ in comparison with baseline and placebo. However, mean power output was greater than placebo during time-trial performance at the 250-kJ and 500-kJ time points (p < .05) after the second SP phase. Furthermore, mean VO2peak values (p < .01) were greater after the SP1 (3.5�4.3%), with further improvements (p < .01) found in SP2 (7.1�7.7%), compared with baseline and placebo. In summary, repeated SP supplementation, ingested either 15 or 35 d after initial loading, can have an additive effect on VO2peak and possibly time-trial performance.
