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Jesse Fleming, Matthew J. Sharman, Neva G. Avery, Dawn M. Love, Ana L. Gómez, Timothy P. Scheett, William J. Kraemer and Jeff S. Volek

The effects of adaptation to a high-fat diet on endurance performance are equivocal, and there is little data regarding the effects on high-intensity exercise performance. This study examined the effects of a high-fat/moderate protein diet on submaximal, maximal, and supramaximal performance. Twenty non-highly trained men were assigned to either a high-fat/moderate-protein (HFMP; 61% fat) diet (n = 12) or a control (C; 25% fat) group (n = 8). A maximal oxygen consumption test, two 30-s Wingate anaerobic tests, and a 45-min timed ride were performed before and after 6 weeks of diet and training. Body mass decreased significantly (–2.2 kg; p ≤ .05) in HFMP subjects. Maximal oxygen consumption significantly decreased in the HFMP group (3.5 ± 0.14 to 3.27 ± 0.09 L · min−1) but was unaffected when corrected for body mass. Perceived exertion was significantly higher during this test in the HFMP group. Main time effects indicated that peak and mean power decreased significantly during bout 1 of the Wingate sprints in the HFMP (–10 and –20%, respectively) group but not the C (–8 and –16%, respectively) group. Only peak power was lower during bout 1 in the HFMP group when corrected for body mass. Despite significantly reduced RER values in the HFMP group during the 45-min cycling bout, work output was significantly decreased (–18%). Adaptation to a 6-week HFMP diet in non-highly trained men resulted in increased fat oxidation during exercise and small decrements in peak power output and endurance performance. These deleterious effects on exercise performance may be accounted for in part by a reduction in body mass and/or increased ratings of perceived exertion.

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Stephen A. Ingham, Barry W. Fudge, Jamie S. Pringle and Andrew M. Jones

Prior high-intensity exercise increases the oxidative energy contribution to subsequent exercise and may enhance exercise tolerance. The potential impact of a high-intensity warm-up on competitive performance, however, has not been investigated.

Purpose:

To test the hypothesis that a high-intensity warm-up would speed VO2 kinetics and enhance 800-m running performance in well-trained athletes.

Methods:

Eleven highly trained middle-distance runners completed two 800-m time trials on separate days on an indoor track, preceded by 2 different warm-up procedures. The 800-m time trials were preceded by a 10-min self-paced jog and standardized mobility drills, followed by either 6 × 50-m strides (control [CON]) or 2 × 50-m strides and a continuous high-intensity 200-m run (HWU) at race pace. Blood [La] was measured before the time trials, and VO2 was measured breath by breath throughout exercise.

Results:

800-m time-trial performance was significantly faster after HWU (124.5 ± 8.3 vs CON, 125.7 ± 8.7 s, P < .05). Blood [La] was greater after HWU (3.6 ± 1.9 vs CON, 1.7 ± 0.8 mM; P < .01). The mean response time for VO2 was not different between conditions (HWU, 27 ± 6 vs CON, 28 ± 7 s), but total O2 consumed (HWU, 119 ± 18 vs CON, 109 ± 28 ml/kg, P = .05) and peak VO2 attained (HWU, 4.21 ± 0.85 vs CON, 3.91 ± 0.63 L/min; P = .08) tended to be greater after HWU.

Conclusions:

These data indicate that a sustained high-intensity warm-up enhances 800-m time-trial performance in trained athletes.

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Ana C. Holt, Daniel J. Plews, Katherine T. Oberlin-Brown, Fabrice Merien and Andrew E. Kilding

recovery time course for parasympathetic activity (Figure  2 ), with HRV return to baseline presenting 29.2 [12.1] hours for threshold IT, followed by glycolytic (17.8 [9.6] h) and VO 2 max IT (15.7 [11.2] h). These findings have practical implications in the programming of high-intensity exercise

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Ryan S. Garten, Matthew C. Scott, Tiffany M. Zúñiga, Austin C. Hogwood, R. Carson Fralin and Jennifer Weggen

have reported beneficial effects on vascular function, the findings from the current study do not implicate a high-intensity exercise bout done prior to sitting to be any more beneficial than a moderate-intensity bout. As the current and prior studies employing this technique utilized a 3-hour bout of

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Renato A.C. Caritá, Camila C. Greco and Benedito S. Denadai

Prior high-intensity exercise can improve exercise performance during severe-intensity exercise. These positive alterations have been attributed, at least in part, to enhancement of overall oxygen-uptake (VO2) kinetics.

Purpose:

To determine the effects of prior heavy-intensity exercise on VO2 kinetics and short-term high-intensity exercise performance in individuals with different aerobic-training statuses.

Methods:

Fifteen active subjects (UT; VO2max = 43.8 ± 6.3 mL · kg−1 · min−1) and 10 well-trained endurance cyclists (T; VO2max = 66.7 ± 6.7 mL · kg−1 · min−1) performed the following protocols: an incremental test to determine lactate threshold and VO2max, 4 maximal constant-load tests to estimate critical power, and two 3-min bouts of cycle exercise, involving 2 min of constant-work-rate exercise at severe intensity followed by a 1-min all-out sprint test. This trial was performed without prior intervention and 10 min after prior heavy-intensity exercise (ie, 6 min at 90% critical power).

Results:

The mean response time of VO2 was shortened after prior exercise for both UT (30.7 ± 9.2 vs 24.1 ± 7.2 s) and T (31.8 ± 5.2 vs 25.4 ± 4.3 s), but no group-by-condition interaction was detected. The end-sprint performance (ie, mean power output) was improved in both groups (UT ~4.7%, T ~2.0%; P < .05) by prior exercise.

Conclusion:

The effect of prior heavy-intensity exercise on overall VO2 kinetics and short-term high-intensity exercise performance is independent of aerobic-training status.

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Thiago R.S. Tenório, P. Babu Balagopal, Lars B. Andersen, Raphael M. Ritti-Dias, James O. Hill, Mara C. Lofrano-Prado and Wagner L. Prado

related to inflammation ( 3 , 13 , 14 , 16 , 26 , 28 ). However, the potential impact of exercise intensity on these markers remains less clear in children. High-intensity exercise interventions have been shown to promote greater improvements in cardiorespiratory fitness ( 6 , 18 ) and body fat ( 9

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Pablo Jodra, Raúl Domínguez, Antonio J. Sánchez-Oliver, Pablo Veiga-Herreros and Stephen J. Bailey

contractions, and that type II muscle is heavily recruited during high-intensity intermittent and all-out sprint exercise. 7 Therefore, the potential for an ergogenic effect following dietary NO 3 − supplementation might be greatest during short-duration, high-intensity exercise, as supported by improved

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Martin J. Barwood, Jo Corbett, John Feeney, Paul Hannaford, Dan Henderson, Ian Jones and Jade Kirke

Purpose:

To establish the thermal and performance effects of wearing a lower-body graduated compression garment (GCG) in a hot environment (35.2°C ± 0.1°C) with a representative radiant heat load (~800 W/m2) in contrast to a control (running shorts) and sham condition (a compression garment 1 size larger than that recommended by the manufacturer), with the latter included to establish any placebo effect.

Method:

Eight participants (mean ± SD; age 21 ± 2 y, height 1.77 ± 0.06 m, mass 72.8 ± 7.1 kg, surface area, 1.89 ± 0.10 m2) completed 3 treadmill tests at a fixed speed for 15 min followed by a self-paced 5-km time trial. Performance (completion time) and pacing (split time), thermal responses (aural, skin, and mean body temperature, cardiac frequency), and perceptual responses (rating of perceived exertion [RPE], thermal sensation, thermal comfort) were measured.

Results:

Performance in the compression group was not different than in either sham or control at any stage (P > .05); completion time 26.08 ± 4.08, 26.05 ± 3.27, and 25.18 ± 3.15 min, respectively. At the end of the 5-km time trial, RPE was not different; it was 19 ± 1 across conditions. In general, thermal and perceptual responses were not different, although the radiant heat load increased site-specific skin temperature (quadriceps) in the garment conditions.

Conclusion:

GCG did not enhance performance in a hot environment with a representative radiant heat load. The sham treatment did not benefit perception. GCG provided no evidence of performance enhancement.

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Ken van Someren, Kathy Fulcher, John McCarthy, Jonathan Moore, Gill Horgan and Richard Langford

This study examined the effect of sodium citrate ingestion on high-intensity cycling performance in repeated 45-s bouts. Twelve subjects (9 male and 3 female) ingested either a sodium citrate solution (0.3 g ⋅ kg−1 body mass [BM]) or a placebo 90 min prior to exercise. Postingestion blood HCO3 concentrations were significantly higher in the citrate trial (p < .01), but there was no difference in blood pH between trials. Peak power and total work significantly decreased over the five bouts (p < .05) and postexercise blood lactate concentrations significantly increased over the five bouts (p < 0.01), but there were no differences between trials. We conclude that sodium citrate ingestion (0.3 g ⋅ kg−1 BM) is not an effective ergogenic aid for high-intensity, intermittent exercise as simulated in this protocol.

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J. Mark Davis, Ralph S. Welsh and Nathan A. Alderson

Purpose:

This study was designed to test the hypothesis that addition of chromium (Cr) to a carbohydrate-electrolyte drink would enhance the reported benefits of carbohydrate on exercise capacity during intermittent high-intensity shuttle running.

Methods:

Eight physically active men performed 3 exercise trials while ingesting 6% carbohydrate-electrolyte (CHO), CHO plus chromium picolinate (400 μg) (CHO + Cr+3). or placebo (P) using a double-blind, counterbalanced design. Each trial consisted of 5 × 15 min bouts of shuttle running (walk, sprint, and run at 95 and 55% of estimated V̇O2max, separated by 3-min rest). This was followed by a fatigue test (running alternating 20-m lengths at 55 and 95% of estimated V̇O2, until fatigue).

Results:

During the standardized shuttle running, blood glucose was higher with both CHO and CHO + Cr+3 than P. Plasma free fatty acid was higher in P than both CHO and CHO + Cr+3 at 75 min of exercise and at fatigue. In the fatigue test, subjects ran longer with both CHO and CHO + Cr+3 than P.

Conclusions:

The data confirm an ergogenic benefit of ingesting CHO during exercise designed to imitate sports like basketball, soccer, and hockey, but do not support the hypothesis that the addition of Cr would enhance this effect.