Effects of commbined sago-soy supplementation on cycling time trial performance in the heat

• Auteur principal: Tarmast, Daniel
• Format: Thèse
• Langue: anglais
• Publié: 2016
• Sujets: RJ Pediatrics
• Accès en ligne: http://eprints.usm.my/41729/

The effects of carbohydrate intake and a combination of carbohydrate and protein intake on endurance performance have been studied by many researchers with equivocal findings. In this study, local food products such as sago starch (containing 88% carbohydrate) and a soy–protein isolate (containing amino acids) has been used. The purpose of the current study was to examine the effects of sago, soy, and iso–caloric combination of sago+soy supplementations during 90 minutes steady–state cycling at 60 % VO2max, on a subsequent 20–km cycling time trial performance in the heat (~31 °C; 70 % relative humidity). Twelve well–trained male cyclists (age: 19.0 ± 5.6 years, body weight: 60.1 ± 11.2 kg, height: 170.8 ± 7.6 cm, and VO2max: 56.5 ± 6.5 mL.kg-1.min-1) representing Kelantan (state level) cycling team were recruited for this randomised single–blind placebo– controlled crossover study. Following preliminary trials, to investigate the VO2max and to determine workload of the steady–state cycling, participants performed four experimental trials. The experimental trials consisted of a 90–minute steady–state pedalling at 60 % of VO2max, followed by a 20–km cycling time trial. From the beginning of the experimental trials and at 20–minute intervals during the steady–state cycling (0, 20, 40, 60, and 80 minutes), participants consumed 200 mL of either: 7.5 % Sago, 7.5 % Soy, 6.0 % Sago + 1.5 % Soy, or placebo. No significant differences were found in time–to–complete the 20–km time trial regardless of the drink ingested (p > 0.05). Metabolic responses including plasma concentrations of glucose and insulin were increased during the steady–state cycling in the sago and sago+soy trials compared with soy and placebo trials. At the end of the 20–km cycling time trial, the plasma lactate concentration was increased significantly in all trials (p < 0.001), and the plasma free fatty acids concentration was significantly higher in the placebo and soy trials than the sago and sago+soy trials (p < 0.001). There were no significant differences between the trials in plasma concentrations of creatine kinase and F2– Isoprostanes after the experimental trials (p > 0.05). The present study demonstrated that ingestion of sago, soy, and iso–caloric sago+soy combined supplementation did not improve the 20–km cycling time trial performance in the heat despite the availability of a higher level of plasma glucose and insulin. Hence, carbohydrate alone or a carbohydrate+protein combined supplementation may not be beneficial in exercise performance, specifically in the heat.