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Nicholas Gant, John B. Leiper and Clyde Williams

This study examined gastric emptying, core temperature, and sprint performance during prolonged intermittent shuttle running in 30 °C when ingesting a carbohydrate-electrolyte solution (CES) or favored water (FW). Nine male soccer players performed 60 min of shuttle running, ingesting fluid before exercise and every 15 min during exercise. Gastric emptying was measured using a double-sampling aspiration technique, and intestinal temperature was monitored via ingested capsules. There were no differences between trials in the total fluid volume emptied from the stomach during each exercise period (P = 0.054). The volume emptied every 15 min was 244 ± 67 mL in the CES trial and 273 ± 66 mL in the FW trial. Intestinal temperature was higher during exercise in the CES trial (P = 0.004), and cumulative sprint time was shorter (P = 0.037). Sprint performance was enhanced by the ingestion of a CES, which resulted in elevated core temperatures, and the rate of gastric emptying remained similar between solutions.

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Laura A. Garvican, Kristal Hammond, Matthew C. Varley, Christopher J. Gore, Francois Billaut and Robert J. Aughey

Purpose:

This study investigated the decrement in running performance of elite soccer players competing at low altitude and time course for abatement of these decrements.

Methods:

Twenty elite youth soccer players had their activity profile, in a sea-level (SL) and 2 altitude (Alt, 1600 m, d 4, and d 6) matches, measured with a global positioning system. Measures expressed in meters per minute of match time were total distance, low- and high-velocity running (LoVR, 0.01–4.16 m/s; HiVR, 4.17–10.0 m/s), and frequency of maximal accelerations (>2.78 m/s2). The peak and subsequent stanza for each measure were identified and a transient fatigue index calculated. Mean heart rate (HR) during the final minute of a submaximal running task (5 min, 11 km/h) was recorded at SL and for 10 d at Alt. Differences were determined between SL and Alt using percentage change and effect-size (ES) statistic with 90% confidence intervals.

Results:

Mean HR almost certainly increased on d 1 (5.4%, ES 1.01 ± 0.35) and remained probably elevated on both d 2 (ES 0.42 ± 0.31) and d3 (ES 0.30 ± 0.25), returning to baseline at d 5. Total distance was almost certainly lower than SL (ES –0.76 ± 0.37) at d 4 and remained probably reduced on d 6 (ES –0.42 ± 0.36). HiVR probably decreased at d 4 vs SL (–0.47 ± 0.59), with no clear effect of altitude at d 6 (–0.08 ± 0.41). Transient fatigue in matches was evident at SL and Alt, with a possibly greater decrement at Alt.

Conclusion:

Despite some physiological adaptation, match running performance of youth soccer players is compromised for at least 6 d at low altitude.

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Costas Chryssanthopoulos, Clyde Williams, Andrea Nowitz, Christina Kotsiopoulou and Veronica Vleck

This study examined the effects of a pre-exercise meal and a carbohydrate-electrolyte solution on endurance running capacity. Ten men performed 3 treadmill runs at 70% V̇O2max to exhaustion after consuming (a) a carbohydrate meal 3 h before exercise and a carbohydrate-electrolyte solution during exercise (M+C); or (b) the carbohydrate meal 3 h before exercise and water during exercise (M+W): or (c) a liquid placebo 3 h before exercise and water during exercise (P+W). Exercise time was longer in M+C (125.1 ±5.3 min; mean±SE) and M+W (111.9 ± 5.6 min) compared with P+W (102.9 ± 7.9 min;p< .01 and p < .05, respectively), and longer in M+C compared with M+W (p < .05). Serum insulin concentration at the start of exercise and carbohydrate oxidation rates during the first hour of exercise were higher, whereas plasma FFA concentrations throughout exercise were lower in M+W and M+C than in P+W (p < .01). A carbohydrate meal before exercise at 70% V̇O2max improved endurance running capacity; however, me combination of the meal and a carbohydrate-electrolyte solution during exercise further improved endurance running capacity.

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Montassar Tabben, Laurent Bosquet and Jeremy B. Coquart

Purpose:

This study examined the effect of performance level on the validity and accuracy of middle-distance running-performance predictions obtained from the nomogram of Mercier et al in male runners.

Methods:

Official French track-running rankings for the 3000-, 5000-, and 10,000-m events from 2006 to 2014 were examined. The performance level was determined from the official reference table of the Fédération Française d’Athlétisme, and the runners were divided in 3 groups (ie, low, moderate, and high levels). Only male runners who performed in the 3 distance events within the same year were included (N = 443). Each performance over any distance was predicted using the nomogram from the 2 other performances.

Results:

No difference was found in low- and moderate-performance-level athletes (0.02 ≤ effect size [ES] ≤ 0.06, 95% limits of agreement [LoA] ≤ 6%). By contrast, a small difference in high-performance-level athletes (P < .01, 0.23 ≤ ES ≤ 0.45, 95% LoA ≤ 11.6%) was found.

Conclusion:

The study confirms the validity of the nomogram to predict track-running performance with a high level of accuracy, except for male runners with high performance level (ie, national or international). Consequently, the predictions from the nomogram may be used in training programs (eg, to prescribe tempo runs with realistic training velocities) and competitions (eg, to plan realistic split times to reach the best performance).

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Stephen H.S Wong, Oi Won Chan, Ya Jun Chen, Heng Long Hu, Ching Wan Lam and Pak Kwong Chung

Purpose:

This study examined the effect of consuming carbohydrate- (CHO) electrolyte solution on running performance after different-glycemic-index (GI) meals.

Methods:

Nine men completed 3 trials in a randomized counterbalanced order, with trials separated by at least 7 days. Two hours before the run after an overnight fast, each participant consumed a high-GI (GI = 83) or low-GI (GI = 36) CHO meal or low-energy sugar-free Jell-O (GI = 0, control). The 2 isocaloric GI meals provided 1.5 g available CHO/kg body mass. During each trial, 2 ml/kg body mass of a 6.6% CHO-electrolyte solution was provided immediately before exercise and every 2.5 km after the start of running. Each trial consisted of a 21-km performance run on a level treadmill. The participants were required to run at 70% VO2max during the first 5 km of the run. They then completed the remaining 16 km as fast as possible.

Results:

There was no difference in the time to complete the 21-km run (high-GI vs. low-GI vs. control: 91.1 ± 2.0 vs. 91.8 ± 2.2 vs. 92.9 ± 2.0 min, n.s.). There were no differences in total CHO and fat oxidation throughout the trials, despite differences in preexercise blood glucose, serum insulin, and serum free-fatty-acid concentrations.

Conclusion:

When a CHO-electrolyte solution is consumed during a 21-km run, the GI of the preexercise CHO meal makes no difference in running performance.

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Ville Vesterinen, Ari Nummela, Sami Äyrämö, Tanja Laine, Esa Hynynen, Jussi Mikkola and Keijo Häkkinen

Regular monitoring of adaptation to training is important for optimizing training load and recovery, which is the main factor in successful training.

Purpose:

To investigate the usefulness of a novel submaximal running test (SRT) in field conditions in predicting and tracking changes of endurance performance.

Methods:

Thirty-five endurance-trained men and women (age 20–55 y) completed the 18-wk endurance-training program. A maximal incremental running test was performed at weeks 0, 9, and 18 for determination of maximal oxygen consumption (VO2max) and running speed (RS) at exhaustion (RSpeak) and lactate thresholds (LTs). In addition, the subjects performed weekly a 3-stage SRT including a postexercise heart-rate-recovery (HRR) measurement. The subjects were retrospectively grouped into 4 clusters according to changes in SRT results.

Results:

Large correlations (r = .60–.89) were observed between RS during all stages of SRT and all endurance-performance variables (VO2max, RSpeak, RS at LT2, and RS at LT1). HRR correlated only with VO2max (r = .46). Large relationships were also found between changes in RS during 80% and 90% HRmax stages of SRT and a change of RSpeak (r = .57, r = .79). In addition, the cluster analysis revealed the different trends in RS during 80% and 90% stages during the training between the clusters, which showed different improvements in VO2max and RSpeak.

Conclusions:

The current SRT showed great potential as a practical tool for regular monitoring of individual adaptation to endurance training without time-consuming and expensive laboratory tests.

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Giorgos P. Paradisis, Athanassios Bissas and Carlton B. Cooke

Purpose:

This study examined the effects of sprint running training on sloping surfaces (3°) on selected kinematic and physiological variables.

Methods:

Fifty-four sport and physical education students were randomly allocated to one of two training groups (combined uphill–downhill [U+D] and horizontal (H)) and a control group (C). Pre- and post training tests were performed to examine the effects of 8 wk of training on the maximum running speed (MRS), step rate, step length, step time, contact time, eccentric and concentric phase of contact time (EP, CP), fight time, selected posture characteristics of the step cycle, and 6-s maximal cycle sprint test.

Results:

MRS, step rate, contact time, and step time were improved significantly in a 35-m sprint test for the U+D group (P < .01) after training by 4.3%, 4.3%, -5.1%, and -3.9% respectively, whereas the H group showed smaller improvements, (1.7% (P < .05), 1.2% (P < .01), 1.7% (P < .01), and 1.2% (P < .01) respectively). There were no significant changes in the C group. The posture characteristics and the peak anaerobic power (AWT) performance did not change with training in any of the groups.

Conclusion:

The U+D training method was significantly more effective in improving MRS and the kinematic characteristics of sprint running than a traditional horizontal training method.

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Abigail S.L. Stickford, Daniel P. Wilhite and Robert F. Chapman

Investigations into ventilatory, metabolic, and hematological changes with altitude training have been completed; however, there is a lack of research exploring potential gait-kinematic changes after altitude training, despite a common complaint of athletes being a lack of leg "turnover" on return from altitude training.

Purpose:

To determine if select kinematic variables changed in a group of elite distance runners after 4 wk of altitude training.

Methods:

Six elite male distance runners completed a 28-d altitude-training intervention in Flagstaff, AZ (2150 m), following a modified “live high–train low” model, wherein higherintensity runs were performed at lower altitudes (945–1150 m) and low-intensity sessions were completed at higher altitudes (1950–2850 m). Gait parameters were measured 2–9 d before departure to altitude and 1 to 2 d after returning to sea level at running speeds of 300–360 m/min.

Results:

No differences were found in ground-contact time, swing time, or stride length or frequency after altitude training (P > .05).

Conclusions:

Running mechanics are not affected by chronic altitude training in elite distance runners. The data suggest that either chronic training at altitude truly has no effect on running mechanics or completing the live high–train low model of altitude training, where higher-velocity workouts are completed at lower elevations, mitigates any negative mechanical adaptations that may be associated with chronic training at slower speeds.

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Stephen D. Patterson and Susan C. Gray

The aim of this study was to investigate the effects of a carbohydrate (CHO) gel on performance after prolonged intermittent high-intensity shuttle running. Seven male soccer players performed 2 exercise trials, 7 d apart. On each occasion, participants completed five 15-min periods of intermittent variable-speed running, interspersed with periods of walking (Part A), followed by an intermittent run to exhaustion (Part B). Participants consumed either a CHO gel or placebo (PLA) immediately before exercise (0.89 mL/kg body mass [BM]) and every 15 min thereafter (0.35 mL/kg BM). In addition, water was consumed at a rate of 5 mL/kg BM before and 2 mL/kg BM every 15 min during exercise. Blood glucose levels were higher (P < 0.05) at 15, 30, and 60 min of exercise and at exhaustion in CHO than in PLA. During Part B, run time to exhaustion was longer (P < 0.05) in the CHO trial (CHO 6.1 ± 1.3 min vs. PLA 4.2 ± 1.2 min). These results indicate that ingesting a CHO gel, along with water, improves performance after prolonged intermittent running in healthy male subjects, possibly by maintaining blood glucose levels during exercise.

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Graham J. Mytton, David T. Archer, Alan St Clair Gibson and Kevin G. Thompson

Purpose:

To assess the reliability and stability of 400-m swimming and 1500-m running competitions to establish the number of samples needed to obtain a stable pacing profile. Coaches, athletes, and researchers can use these methods to ensure that sufficient data are collected before training and race strategies are constructed or research conclusions are drawn.

Method:

Lap times were collected from 5 world and European championship finals between 2005 and 2011, resulting in the capture of data from 40 swimmers and 55 runners. A cumulative mean for each lap was calculated, starting with the most recent data, and the number of races needed for this to stabilize to within 1% was reported. Typical error for each lap was calculated for athletes who had competed in more than 1 final.

Results:

International swimmers demonstrated more reproducible performances than runners in 3 of the 4 laps of the race (P < .01). Variance in runners’ lap times significantly decreased by 1.7–2.7% after lap 1, whereas variance in swimmers’ lap times tended to increase by 0.1–0.5% after lap 1. To establish a stable profile, at least ten 400-m swimmers and forty-four 1500-m runners must be included.

Conclusions:

A stable race profile was observed from the analysis of 5 events for 1500-m running and 3 events for 400-m swimming. Researchers and athletes can be more certain about the pacing information collected from 400-m swimming than 1500-m running races, as the swimming data are less variable, despite both events being of similar duration.