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Joanne L. Fallowfield and Clyde Williams

The influence of increased carbohydrate intake on endurance capacity was investigated following a bout of prolonged exercise and 22.5 hrs of recovery. Sixteen male subjects were divided into two matched groups, which were then randomly assigned to either a control (C) or a carbohydrate (CHO) condition. Both groups ran at 70% VO2max on a level treadmill for 90 min or until volitional fatigue, whichever came first (T1), and 22.5 hours later they ran at the same % VO2max for as long as possible to assess endurance capacity (T2). During the recovery, the carbohydrate intake of the CHO group was increased from 5.8 (±0.5) to 8.8 (±0.1) g kg-1 BW. This was achieved by supplementing their normal diet with a 16.5% glucose-polymer solution. An isocaloric diet was prescribed for the C group, in which additional energy was provided in the form of fat and protein. Run times over T1 did not differ between the groups. However, over T2 the run time of the C group was reduced by 15.57 min (p<0.05), whereas those in the CHO group were able to match their T1 performance. Blood glucose remained stable throughout Tl and T2 in both groups. In contrast, blood lactate, plasma FFA, glycerol, ammonia, and urea increased. Thus, a high carbohydrate diet restored endurance capacity within 22.5 hrs whereas an isocaloric diet without additional carbohydrate did not.

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Ricardo J.S. Costa, Vera Camões-Costa, Rhiannon M.J. Snipe, David Dixon, Isabella Russo and Zoya Huschtscha

immunity, potentially leaving the individual open to opportunistic pathogenic agents and suboptimal recovery processes ( Russo et al., 2019 ; Walsh, 2018 ). Furthermore, neutrophil chemotaxis, phagocytic ability, pathogenic termination, and/or tissue debris demolition functions (e

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Brian Dawson

Repeated-sprint ability (RSA) is now well accepted as an important fitness component in team-sport performance. It is broadly described as the ability to perform repeated short (~3–4 s, 20–30 m) sprints with only brief (~10–30 s) recovery between bouts. Over the past 25 y a plethora of RSA tests have been trialed and reported in the literature. These range from a single set of ~6–10 short sprints, departing every 20–30 s, to team-sport game simulations involving repeating cycles of walk-jog-stride-sprint movements over 45–90 min. Such a wide range of RSA tests has not assisted the synthesis of research findings in this area, and questions remain regarding the optimal methods of training to best improve RSA. In addition, how RSA test scores relate to player “work rate,” match performance, or both requires further investigation to improve the application of RSA testing and training to elite team-sport athletes.

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Jamie Douglas, Daniel J. Plews, Phil J. Handcock and Nancy J. Rehrer

Purpose:

To determine whether a facilitated recovery via cold-water immersion (CWI) after simulated rugby sevens would influence parasympathetic reactivation and repeated-sprint (RS) performance across 6 matches in a 2-d tournament.

Methods:

Ten male team-sport athletes completed 6 rugby sevens match simulations over 2 d with either postmatch passive recovery (PAS) or CWI in a randomized crossover design. Parasympathetic reactivation was determined via the natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (ln rMSSD). RS performance was calculated as time taken (s) to complete 6 × 30-m sprints within the first half of each match.

Results:

There were large increases in postintervention ln rMSSD between CWI and PAS after all matches (ES 90% CL: +1.13; ±0.21). Average heart rate (HR) during the RS performance task (HRAverage RS) was impaired from baseline from match 3 onward for both conditions. However, HRAverage RS was higher with CWI than with PAS (ES 90% CL: 0.58; ±0.58). Peak HR during the RS performance task (HRPeak RS) was similarly impaired from baseline for match 3 onward during PAS and for match 4 onward with CWI. HRPeak RS was very likely higher with CWI than with PAS (ES 90% CL: +0.80; ±0.56). No effects of match or condition were observed for RS performance, although there were moderate correlations between the changes in HRAverage RS (r 90% CL: –0.33; ±0.14), HRPeak RS (r 90% CL: –0.38; ±0.13), and RS performance.

Conclusion:

CWI facilitated cardiac parasympathetic reactivation after a simulated rugby sevens match. The decline in average and peak HR across matches was partially attenuated by CWI. This decline was moderately correlated with a reduction in RS performance.

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Ian Craig Perkins, Sarah Anne Vine, Sam David Blacker and Mark Elisabeth Theodorus Willems

We examined the effect of New Zealand blackcurrant (NZBC) extract on high-intensity intermittent running and postrunning lactate responses. Thirteen active males (age: 25 ± 4 yrs, height: 1.82 ± 0.07 m, body mass: 81 ± 14 kg, V̇O2max: 56 ± 4 ml∙kg-1∙min-1, v V̇O2max: 17.6 ± 0.8 km∙h-1) performed a treadmill running protocol to exhaustion, which consisted of stages with 6 × 19 s of sprints with 15 s of low-intensity running between sprints. Interstage rest time was 1 min and stages were repeated with increasing sprint speeds. Subjects consumed capsuled NZBC extract (300 mg∙day-1 CurraNZ; containing 105 mg anthocyanin) or placebo for 7 days (double-blind, randomized, crossover design, wash-out at least 14 days). Blood lactate was collected for 30 min postexhaustion. NZBC increased total running distance by 10.6% (NZBC: 4282 ± 833 m, placebo: 3871 ± 622 m, p = .02), with the distance during sprints increased by 10.8% (p = .02). Heart rate, oxygen uptake, lactate and rating of perceived exertion were not different between conditions for the first 4 stages completed by all subjects. At exhaustion, blood lactate tended to be higher for NZBC (NZBC: 6.01 ± 1.07 mmol∙L-1, placebo: 5.22 ± 1.52 mmol∙L-1, p = .07). There was a trend for larger changes in lactate following 15 min (NZBC: -2.89 ± 0.51 mmol∙L-1, placebo: -2.46 ± 0.39 mmol∙L-1, p = .07) of passive recovery. New Zealand blackcurrant extract (CurraNZ) may enhance performance in sports characterized by high-intensity intermittent exercise as greater distances were covered with repeated sprints, there was higher lactate at exhaustion, and larger changes in lactate during early recovery after repeated sprints to exhaustion.

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Conor Taylor, Daniel Higham, Graeme L. Close and James P. Morton

The aim of this study was to test the hypothesis that adding caffeine to postexercise carbohydrate (CHO) feedings improves subsequent high-intensity interval-running capacity compared with CHO alone. In a repeated-measures design, 6 men performed a glycogen-depleting exercise protocol until volitional exhaustion in the morning. Immediately after and at 1, 2, and 3 hr postexercise, participants consumed 1.2 g/kg body mass CHO of a 15% CHO solution, a similar CHO solution but with addition of 8 mg/kg body mass of caffeine (CHO+CAFF), or an equivalent volume of flavored water only (WAT). After the 4-hr recovery period, participants performed the Loughborough Intermittent Shuttle Test (LIST) to volitional exhaustion as a measure of high-intensity interval-running capacity. Average blood glucose values during the 4-hr recovery period were higher in the CHO conditions (p < .005) than in the WAT trial (4.6 ± 0.3 mmol/L), although there was no difference (p = .46) between CHO (6.2 ± 0.8 mmol/L) and CHO+CAFF (6.7 ± 1.0 mmol/L). Exercise capacity during the LIST was significantly longer in the CHO+CAFF trial (48 ± 15 min) than in the CHO (32 ± 15 min, p = .04) and WAT conditions (19 ± 6 min, p = .001). All 6 participants improved performance in CHO+CAFF compared with CHO (95% CI for mean difference = 1–32 min). The study provides novel data by demonstrating that adding caffeine to postexercise CHO feeding improves subsequent high-intensity interval-running capacity, a finding that may be related to higher rates of postexercise muscle glycogen resynthesis previously observed under similar feeding conditions.

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Leilani Madrigal

Psychological skills such as goal setting, imagery, relaxation and self-talk have been used in performance enhancement, emotional regulation, and increasing one’s confidence and/or motivation in sport. These skills can also be applied with athletes during recovery from injury in the rehabilitation setting or in preseason meetings for preventing injury. Research on psychological skill use with athletes has shown that such skills have helped reduce negative psychological outcomes, improve coping skills, and reduce reinjury anxiety (Evans & Hardy, 2002; Johnson, 2000; Mankad & Gordon, 2010). Although research has been limited in psychological skill implementation with injured athletes, these skills can be used when working with injured athletes or in the prevention of injury. Injured athletes may use psychological skills such as setting realistic goals in coming back from injury, imagery to facilitate rehabilitation, and relaxation techniques to deal with pain management. In prevention of injury, the focus is on factors that put an individual at-risk for injury. Thus, teaching strategies of goal setting, imagery, relaxation techniques, and attention/focus can be instrumental in preparing athletes for a healthy season.

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Fred Brouns, Mikael Fogelholm, Gerrit van Hall, Anton Wagenmakers and Wim H.M. Saris

This study tested the hypothesis that a 3-week oral lactate supplementation affects postexercise blood lactate disappearance in untrained male subjects. Fifteen men were randomly assigned to either a lactate supplementation (n = 8) or a placebo (n = 7) treatment. During the treatment period they drank an oral lactate or a maltodextrin (placebo) supplement twice a day. The lactate drink contained 10 g of lactate as calcium, sodium, and potassium salts. Blood lactate concentrations were studied before, during, and immediately after three exercise tests, both pre-and posttreatment. Peak lactate values for placebo (PL) or lactate (L) treatment groups during different tests were as follows: Test 1 PL, 13.49 ± 3.71; L, 13.70 ± 1.90; Test 2 PL, 12.64 ± 2.32; L, 12.00 ± 2.23; Test 3 PL, 12.29 ± 2.92; L, 11.35 ± 1.38 and were reached 3 min postexercise. The decrease in blood lactate during the long (30- to 45-min) recovery periods amounted to @ 10 mmol/L. Blood lactate changes were highly reproducible. However, a 3-week oral lactate supplementation did not result in differences in lactate disappearance. This study does not support the hypothesis that regular oral lactate intake at rest enhances the removal of lactate during and following exercise, that is, not with the given lactate load and supplementation period.

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William McGarvey, Richard Jones and Stewart Petersen

The purpose of this investigation was to examine the effect of interval (INT) and continuous (CON) cycle exercise on excess post-exercise oxygen consumption (EPOC). Twelve males first completed a graded exercise test for VO2max and then the two exercise challenges in random order on separate days approximately 1 wk apart. The INT challenge consisted of seven 2 min work intervals at 90% VO2max, each followed by 3 min of relief at 30% VO2max. The CON exercise consisted of 30 to 32 min of continuous cycling at 65% VO2max. Gas exchange and heart rate (HR) were measured for 30 min before, during, and for 2 h post-exercise. Three methods were used to analyze post-exercise oxygen consumption and all produced similar results. There were no significant differences in either the magnitude or duration of EPOC between the CON and INT protocols. HR, however, was higher (P < 0.05) while respiratory exchange ratio (RER) was lower (P < 0.05) following INT. These results indicate that when total work was similar, the magnitude and duration of EPOC were similar following CON or INT exercise. The differences in HR and RER during recovery suggest differential physiological responses to the exercise challenges.

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Amy Warren, Erin J. Howden, Andrew D. Williams, James W. Fell and Nathan A. Johnson

Postexercise fat oxidation may be important for exercise prescription aimed at optimizing fat loss. The authors examined the effects of exercise intensity, duration, and modality on postexercise oxygen consumption (VO2) and substrate selection/respiratory-exchange ratio (RER) in healthy individuals. Three experiments (n = 7 for each) compared (a) short- (SD) vs. long-duration (LD) ergometer cycling exercise (30 min vs. 90 min) matched for intensity, (b) low- (LI) vs. high-intensity (HI) cycling (50% vs. 85% of VO2max) matched for energy expenditure, and (c) continuous (CON) vs. interval (INT) cycling matched for energy expenditure and mean intensity. All experiments were administered by crossover design. Altering exercise duration did not affect postexercise VO2 or RER kinetics (p > .05). However, RER was lower and fat oxidation was higher during the postexercise period in LD vs. SD (p < .05). HI vs. LI resulted in a significant increase in total postexercise energy expenditure and fat oxidation (p < .01). Altering exercise modality (CON vs. INT) did not affect postexercise VO2, RER, or fat oxidation (p > .05). These results demonstrate that postexercise energy expenditure and fat oxidation can be augmented by increasing exercise intensity, but these benefits cannot be exploited by undertaking interval exercise (1:2-min work:recovery ratio) when total energy expenditure, duration, and mean intensity remain unchanged. In spite of the apparent benefit of these strategies, the amount of fat oxidized after exercise may be inconsequential compared with that oxidized during the exercise bout.