Effects of Phosphate Loading on Bicycle Time Trial Performance

Weatherwax, R. S.; Ahlberg, A.; Deady, M.; Otto, Robert M.; Perez, H. R.; Cooperstein, Deborah; Wygand, John

doi:10.1249/00005768-198604001-00056

Cited by 5 publications

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“…While 1,000-kJ time-trial time to completion decreased (58-69 s) and power output increased (~5-7 W) after both SP trials, compared with placebo and baseline, the only significant results found were during the second SP phase for mean power at 250 kJ and 500 kJ compared with placebo. Furthermore, while a single phase of SP supplementation resulted in a greater mean Results from previous studies assessing the effect of a single phase of SP supplementation on time-trial performance have been equivocal (Folland et al, 2008;Kreider et al, 1992;Kreider et al, 1990;Weatherwax et al, 1986). Differences between results of these studies could relate to the mode of exercise used (cycling vs. running), the distance of the time trial (range of 8-40 km), and the length of the washout period (9-17 days).…”

Section: Discussionmentioning

confidence: 94%

“…Supplementation with SP typically involves ingestion of 3-4 g/day, split into four equal doses, for a period of 3-6 days (Cade et al, 1984;Folland et al, 2008;Kreider et al, 1992;Kreider et al, 1990;Wallace et al, 1997). Such doses have been reported to result in improvements in VO 2peak (Cade et al, 1984;Kreider et al, 1992;Wallace et al, 1997) and endurance performance (Kreider et al, 1992), although not all studies have observed ergogenic benefits after SP supplementation (Brennan & Connolly, 2001;Thompson et al, 1990;Weatherwax et al, 1986;West, Ayton, Wallman, & Guelfi, 2012). Nonetheless, multiple mechanisms for performance improvements after SP loading have been suggested, including increased 2,3-DPG concentrations, leading to a greater unloading of oxygen from hemoglobin to the muscle (Cade et al 1984;Chanutin & Curnish, 1967;Farber et al, 1987); increased extracellular phosphate availability, resulting in greater intracellular diffusion and enhanced oxidative metabolism (Lichtman, Miller, Cohen, & Waterhouse, 1971;Thompson et al, 1990); increased anaerobic glycolysis, phosphocreatine synthesis, and ATP production (Brain & Card, 1972;Chanutin and Curnish, 1967;Lichtman & Miller, 1970); increased cardiac muscle contractility (Czuba, Zajac, Poprzecki, & Cholewa, 2009;Czuba, Zajac, Poprzecki, Cholewa, & Woska, 2008;Kreider et al, 1992); and increased buffering capacity (Avioli, 1988).…”

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Effect of Repeated Sodium Phosphate Loading on Cycling Time-Trial Performance and VO2peak

Brewer

Dawson

Wallman

et al. 2013

International Journal of Sport Nutrition and Exercise Metabolism

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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.

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Section: Discussionmentioning

confidence: 94%

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Effect of Repeated Sodium Phosphate Loading on Cycling Time-Trial Performance and VO2peak

Brewer

Dawson

Wallman

et al. 2013

International Journal of Sport Nutrition and Exercise Metabolism

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The effects of acute phosphate supplementation in subjects of different aerobic fitness levels

Galloway

Tremblay

Sexsmith

et al. 1996

Europ. J. Appl. Physiol.

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Six trained cyclists (high-fitness group) and six untrained individuals (low-fitness group), performed a 20-min cycle ergometer exercise test at 70% of maximum oxygen consumption (VO2max) followed by a 30-min rest period and then an incremental ride to exhaustion on two occasions, 1 week apart. Ninety minutes prior to exercise subjects consumed a drink containing either 22.2 g dibasic calcium phosphate (DCP; treatment) or calcium carbonate (placebo). Blood was drawn prior to drink ingestion, during submaximal exercise, during recovery and at exhaustion for determination of blood 2,3-DPG, blood ATP, plasma lactate, plasma phosphate, haemoglobin and haematocrit. Throughout exercise, cardiorespiratory variables [oxygen uptake (VO2), minute ventilation, (VE), respiratory exchange ratio, heart rate and oxygen pulse] were monitored, and ratings of perceived exertion obtained. Although there was a trend for the low-fitness group to have a higher plasma phosphate concentration prior to treatment ingestion, no treatment effects on plasma phosphate were noted at any sample time in either group. 2,3-DPG, VO2, oxygen pulse, VE, time to exhaustion and VO2max were significantly higher in the high-fitness group; however, no differences in these variables were observed as a result of phosphate ingestion. Plasma lactate was significantly lower in the high-fitness group during the submaximal exercise and the recovery period, but again phosphate ingestion had no effect. These results suggest that acute DCP supplementation is not effective as an ergogenic aid and that aerobic fitness level does not affect the response to phosphate supplementation.

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Minerals: Exercise performance and supplementation in athletes*

Clarkson

1991

Journal of Sports Sciences

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This paper examines whether mineral supplements are necessary for athletes, and whether these supplements will enhance performance. Macrominerals (calcium, magnesium, and phosphorus) and trace minerals (zinc, copper, selenium, chromium, and iron) are described. Calcium supplements are important for the health of bones. Athletes tend to have enhanced calcium status as assessed by bone mineral density, with the notable exception of female amenorrhoeic athletes. Magnesium status is adequate for most athletes, and there is no evidence that magnesium supplements can enhance performance. Phosphorus status is adequate for athletes. Phosphorus supplementation over an extended period of time can result in lowered blood calcium, however, some studies have shown that acute 'phosphate loading' will enhance performance. Athletes may have a zinc deficiency induced by poor diet and loss of zinc in sweat and urine. Limited data exist on the relationship of performance and zinc status. Widespread deficiencies in copper have not been documented, and there are no data to suggest that copper supplementation will enhance performance. There is no reason to suspect a selenium deficiency in athletes. The relationship between selenium status and performance has not been established, but selenium may play a role as an antioxidant. Because of the low intakes of chromium for the general population, there is a possibility that athletes may be deficient. Exercise may create a loss in chromium because of increased excretion into the urine. Many athletes, particularly female, are iron depleted, but true iron deficiencies are rare. Iron depletion does not affect exercise performance but iron deficiency anaemia does. Iron supplements have not been shown to enhance performance except where iron deficiency anaemia exists. In conclusion, poor diets are perhaps the main reason for any mineral deficiencies found in athletes, although in certain cases exercise could contribute to the deficiency. Mineral supplementation may be important to ensure good health, but few studies have definitively documented any beneficial effect of mineral supplementation on performance.

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Effects of Phosphate Loading on Bicycle Time Trial Performance

Cited by 5 publications

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Effect of Repeated Sodium Phosphate Loading on Cycling Time-Trial Performance and VO2peak

Effect of Repeated Sodium Phosphate Loading on Cycling Time-Trial Performance and VO2peak

The effects of acute phosphate supplementation in subjects of different aerobic fitness levels

Minerals: Exercise performance and supplementation in athletes*

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