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Sonya L. Cameron, Rebecca T. McLay-Cooke, Rachel C. Brown, Andrew R. Gray and Kirsty A. Fairbairn

Purpose:

This study investigated the effect of ingesting 0.3 g/kg body weight (BW) of sodium bicarbonate (NaHCO3) on physiological responses, gastrointestinal (GI) tolerability, and sprint performance in elite rugby union players.

Methods:

Twenty-five male rugby players, age 21.6 (2.6) yr, participated in a randomized, double-blind, placebo-controlled crossover trial. Sixty-five minutes after consuming 0.3 g/kg BW of either NaHCO3 or placebo, participants completed a 25-min warm-up followed by 9 min of high-intensity rugby-specific training followed by a rugby-specific repeated-sprint test (RSRST). Whole-blood samples were collected to determine lactate and bicarbonate concentrations and pH at baseline, after supplement ingestion, and immediately after the RSRST. Acute GI discomfort was assessed by questionnaire throughout the trials, and chronic GI discomfort was assessed during the 24 hr postingestion.

Results:

After supplement ingestion and immediately after the RSRST, blood HCO3 concentration and pH were higher for the NaHCO3 condition than for the placebo condition (p < .001). After the RSRST, blood lactate concentrations were significantly higher for the NaHCO3 than for the placebo condition (p < .001). There was no difference in performance on the RSRST between the 2 conditions. The incidence of belching, stomachache, diarrhea, stomach bloating, and nausea was higher after ingestion of NaHCO3 than with placebo (all p < .050). The severity of stomach cramps, belching, stomachache, bowel urgency, diarrhea, vomiting, stomach bloating, and flatulence was rated worse after ingestion of NaHCO3 than with placebo (p < .050).

Conclusions:

NaHCO3 supplementation increased blood HCO3 concentration and attenuated the decline in blood pH compared with placebo during high-intensity exercise in well-trained rugby players but did not significantly improve exercise performance. The higher incidence and greater severity of GI symptoms after ingestion of NaHCO3 may negatively affect physical performance, and the authors strongly recommend testing this supplement during training before use in competitive situations.

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Sara Dean, Andrea Braakhuis and Carl Paton

Researchers have long been investigating strategies that can increase athletes’ ability to oxidize fatty acids and spare carbohydrate, thus potentially improving endurance capacity. Green-tea extract (epigallocatechin-3-gallate; EGCG) has been shown to improve endurance capacity in mice. If a green-tea extract can stimulate fat oxidation and as a result spare glycogen stores, then athletes may benefit through improved endurance performance. Eight male cyclists completed a study incorporating a 3-way crossover, randomized, placebo-controlled, double-blinded, diet-controlled research design. All participants received 3 different treatments (placebo 270 mg, EGCG 270 mg, and placebo 270 mg + caffeine 3 mg/kg) over a 6-day period and 1 hr before exercise testing. Each participant completed 3 exercise trials consisting of 60 min of cycling at 60% maximum oxygen uptake (VO2max) immediately followed by a self-paced 40-km cycling time trial. The study found little benefit in consuming green-tea extract on fat oxidation or cycling performance, unlike caffeine, which did benefit cycling performance. The physiological responses observed during submaximal cycling after caffeine ingestion were similar to those reported previously, including an increase in heart rate (EGCG 147 ± 17, caffeine 146 ± 19, and placebo 144 ± 15 beats/min), glucose at the 40-min exercise time point (placebo 5.0 ± 0.8, EGCG 5.4 ± 1.0, and caffeine 5.8 ± 1.0 mmol/L), and resting plasma free fatty acids and no change in the amount of carbohydrate and fat being oxidized. Therefore, it was concluded that green-tea extract offers no additional benefit to cyclists over and above those achieved by using caffeine.

Open access

Øyvind Sandbakk

validating or using technology to gain valuable insights into sport physiology and performance. Technology-driven digital solutions may provide knowledge beyond what standard measurements have previously allowed. Positioning systems, inertial movement units, and various sensors that measure physiological

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Tatiane Piucco, Fernando Diefenthaeler, Rogério Soares, Juan M. Murias and Guillaume Y. Millet

become biomechanically or technically difficult to skate fast enough to fully challenge the cardiovascular system. 11 As an alternative, some researchers investigated physiological responses obtained during low walking on an oversized motor-driven treadmill, which simulated the posture used in speed

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Diogo V. Leal, Lee Taylor and John Hough

detect alterations in the exercise-induced responses of these hormones as a consequence of intensified training period. To be of value in practice, this running 55/80 variant protocol must demonstrate reproducible hormone and physiological responses when participants are in a rested healthy state. The

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Achraf Ammar, Stephen J. Bailey, Omar Hammouda, Khaled Trabelsi, Nabil Merzigui, Kais El Abed, Tarak Driss, Anita Hökelmann, Fatma Ayadi, Hamdi Chtourou, Adnen Gharbi and Mouna Turki

bases of these potential surface-dependent effects on physical and technical components of football performance are poorly defined. Empirical research studies assessing physiological responses to exercise performed on AT compared with NG have yielded inconsistent findings. 3 Although higher blood

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Davide Ferioli, Diego Rucco, Ermanno Rampinini, Antonio La Torre, Marco M. Manfredi and Daniele Conte

enhance players’ passing skill, court vision, and players’ collaboration. 6 , 11 However, this rule modification might also simultaneously affect the physiological responses to GBD and the relative activity demands. Understanding the effect of dribbling limitation on these variables is fundamental to

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Heita Goto and James A. King

, Goncalves BS , Sampaio JE . Physiological responses and activity profiles of football small-sided games . J Strength Cond Res . 2013 ; 27 : 1287 – 94 . PubMed ID: 22820211 doi:10.1519/JSC.0b013e318267a35c 22820211 10.1519/JSC.0b013e318267a35c 2. Bradley PS , Carling C , Archer D , et

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Christopher Byrne and Jason K.W. Lee

, sensitivity to rest and recovery periods, and potential for real-time use. 3 By employing 2 physiological responses (ie, TC and HR) that can be measured simultaneously in the field, 6 – 8 the PSI offers utility as a heat strain monitoring tool for individuals performing in the natural environment. The

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Emerson Franchini

possible to calculate the anaerobic speed or power reserve, which has been reported to decrease the performance and physiological responses variability during 1 HIIT protocol. 38 Recently, many combat sports-specific tests were created and validated, 39 and therefore, they can be used to prescribe sport