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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.

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Stephen Seiler and Øystein Sylta

The purpose of this study was to compare physiological responses and perceived exertion among well-trained cyclists (n = 63) performing 3 different high-intensity interval-training (HIIT) prescriptions differing in work-bout duration and accumulated duration but all prescribed with maximal session effort. Subjects (male, mean ± SD 38 ± 8 y, VO2peak 62 ± 6 mL · kg–1 · min–1) completed up to 24 HIIT sessions over 12 wk as part of a training-intervention study. Sessions were prescribed as 4 × 16, 4 × 8, or 4 × 4 min with 2-min recovery periods (8 sessions of each prescription, balanced over time). Power output, HR, and RPE were collected during and after each work bout. Session RPE was reported after each session. Blood lactate samples were collected throughout the 12 wk. Physiological and perceptual responses during >1400 training sessions were analyzed. HIIT sessions were performed at 95% ± 5%, 106% ± 5%, and 117% ± 6% of 40-min time-trial power during 4 × 16-, 4 × 8-, and 4 × 4-min sessions, respectively, with peak HR in each work bout averaging 89% ± 2%, 91% ± 2%, and 94% ± 2% HRpeak. Blood lactate concentrations were 4.7 ± 1.6, 9.2 ± 2.4, and 12.7 ± 2.7 mmol/L. Despite the common prescription of maximal session effort, RPE and sRPE increased with decreasing accumulated work duration (AWD), tracking relative HR. Only 8% of 4 × 16-min sessions reached RPE 19–20, vs 61% of 4 × 4-min sessions. The authors conclude that within the HIIT duration range, performing at “maximal session effort” over a reduced AWD is associated with higher perceived exertion both acutely and postexercise. This may have important implications for HIIT prescription choices.

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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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Matheus Hausen, Pedro Paulo Soares, Marcus Paulo Araujo, Débora Esteves, Hilbert Julio, Roberto Tauil, Marcus Junca, Flávia Porto, Emerson Franchini, Craig Alan Bridge and Jonas Gurgel

stage. A secondary aim was to compare the physiological responses to taekwondo-specific tests that incorporate continuous and intermittent stage increments. Methods Participants Twelve male taekwondo athletes (mean [SD], age: 20 [2] y; body mass: 67.5 [5.7] kg; height: 175 [8] cm; body fat percentage: 8