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Alan Chorley, Richard P. Bott, Simon Marwood and Kevin L. Lamb

the present study was to examine whether repeated bouts of maximal exercise, thus fully depleting W ′, affect the rate of reconstitution of W ′. A secondary aim of the present study was to assess the reliability of a repeated ramp test (RRT) to quantify an individual’s reconstitution of W ′ and to

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Glen E. Duncan, Anthony D. Mahon, Cheryl A. Howe and Pedro Del Corral

This study examined the influence of test duration and anaerobic capacity on VO2max and the occurrence of a VO2 plateau during treadmill exercise in 25 boys (10.4 ± 0.8 years). Protocols with 1-min (P1) and 2-min (P2) stages, but identical speed and grade changes, were used to manipulate test duration. On separate days, VO2max was measured on P1 and P2, and 200-m run time was assessed. At maximal exercise, VO2, heart rate (HR), and pulmonary ventilation (VE) were similar between protocols, however, respiratory exchange ratio (RER) and treadmill elevation were higher (p < .05) on P1 than on P2. Plateau achievement was not significantly different. On P1, there were no differences between plateau achievers and nonachievers. On P2, test duration and 200-m run time were superior (p < .05), and relative VO2max tended to be higher (p < .10) in plateau achievers. Indices of aerobic and anaerobic capacity may influence plateau achievement on long, but not short duration tests.

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Susan Vrijkotte, Romain Meeusen, Cloe Vandervaeren, Luk Buyse, Jeroen van Cutsem, Nathalie Pattyn and Bart Roelands

to mental fatigue as does maximal exercise. During submaximal exercise until exhaustion 7 and self-paced physical tasks, 21 , 22 physical performance was found to be affected when being mentally fatigued. The study of Pageaux et al 23 showed that mental fatigue has a negative influence on the

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Anthony D. Mahon and Melinda L. Marsh

This study examined the occurrence of a V̇O2 plateau at maximal exercise, and whether ventilatory threshold (VT) differend between children who do and children who do not achieve a V̇O2 plateau at maximal exercise. After performing a graded exercise test on a treadmill to assess VT and V̇O2max, the children were divided into a plateau group (n = 14) and a nonplateau group (n = 12). There were no differences with respect to the V̇O2 at VT (36.7 ± 3.4 vs. 37.9 ± 5.4 ml · kg−1 · min−1) and V̇O2max (51.6 ± 5.4 vs. 54.6 ± 3.6 ml · kg−1 · min−1) in the plateau and nonpiateau groups, respectively. The mean HR, RER, and RPE at maximal exercise were also similar between groups. These results indicate that VT and V̇O2max are similar in children regardless of the occurrence of a V̇O2 plateau at maximal exercise. Furthermore, a plateau in V̇O2 during a maximal exercise test is not mandatory for assessment of V̇O2max in this age group.

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Justin P. Guilkey, Brandon Dykstra, Jennifer Erichsen and Anthony D. Mahon

Purpose:

This study examined heart rate recovery (HRR) and heart rate variability (HRV) following maximal exercise in lean (<85th percentile age- and sex-BMI percentile; n = 11 (♂=5; ♀=6); 10.1 ± 0.7 years) and overweight (≥85th age- and sex-BMI percentile; n = 11 (♂=5; ♀=6); 10.5 ± 1.2 years) children.

Method:

Participants completed a 10-min rest, followed by a graded exercise test to maximal effort. HRV, in the time and frequency domains, was assessed during rest and recovery. Also during recovery, one-minute HRR and the time constant of a monoexponential line of best fit (HRRt) were determined.

Results:

There were no significant differences in one-minute HRR and HRRt between the lean (56 ± 7 beats∙min-1 and 160.4 ± 80.1 s, respectively) and overweight (51 ± 16 beats∙min-1 and 141.1 ± 58.1 s, respectively) groups. There also were no significant interactions between groups from rest to recovery for any HRV variables. Root mean square of successive differences (RMSSD) and high frequency power (HF) during recovery was 2.05 ± 0.49 ms and 3.30 ± 1.02 ms2 in the lean children, respectively. In the overweight children, RMSSD and HF were 1.88 ± 0.65 ms and 2.94 ± 1.27 ms2, respectively.

Conclusion:

HRR and HRV findings suggest there are no differences in autonomic function during recovery from maximal exercise in lean and obese 8- to 12-year old children.

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Mahmoud S. El-Sayed, Angelheart J.M. Rattu and Ian Roberts

The study examined the effect of carbohydrate ingestion on exercise performance capacity. Nine male cyclists performed two separate trials at 70% VO2max for 60 min followed by a maximal ride for 10 min. During trials subjects were fed either an 8% glucose solution (CHO) or a placebo solution (PL), which were administered at rest and during and immediately after submaximal exercise. Statistical analyses indicated that glucose levels at rest increased significantly 15 min after the ingestion of CHO compared to PL. At 30 and 60 min during submaximal exercise, plasma glucose levels decreased significantly in the CHO but not in the PL trial. Following the performance ride, glucose levels increased significantly only during the CHO test trial. Free fatty acids did not change significantly during testing trials. The maximal performance ride results showed that in the CHO trial, a significantly greater external work load was accomplished compared to the PL trial. It is concluded that CHO ingestion improves maximal exercise performance after prolonged exercise.

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Amanda Zaleski, Beth Taylor, Braden Armstrong, Michael Puglisi, Priscilla Clarkson, Stuart Chipkin, Charles Michael White, Paul D. Thompson and Linda S. Pescatello

maximal exercise has yet to be examined in otherwise healthy adults. This is surprising because the hemodynamic response to maximal exercise is considered an important clinical marker and screening tool for individuals at risk for future incident hypertension prior to its development ( Kim & Ha, 2016

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Abderraouf Ben Abderrahman, Jacques Prioux, Karim Chamari, Omar Ben Ounis, Zouhair Tabka and Hassane Zouhal

The effect of endurance interval training (IT) on hematocrit (Ht), hemoglobin (Hb), and estimated plasma-volume variation (PVV) in response to maximal exercise was studied in 15 male subjects (21.1 ± 1.1 y; control group n = 6, and training group, n = 9). The training group participated in interval training 3 times a week for 7 wk. A maximal graded test (GXT) was performed to determine maximal aerobic power (MAP) and maximal aerobic speed (MAS) both before and after the training program. To determine Ht, Hb concentration, and lactate concentrations, blood was collected at rest, at the end of GXT, and after 10 and 30 min of recovery. MAP and MAS increased significantly (P < .05) after training only in training group. Hematocrit determined at rest was significantly lower in the training group than in the control group after the training period (P < .05). IT induced a significant increase of estimated PVV at rest for training group (P < .05), whereas there were no changes for control group. Hence, significant relationships were observed after training between PVV determined at the end of the maximal test and MAS (r = .60, P < .05) and MAP (r = .76, P < .05) only for training group. In conclusion, 7 wk of IT led to a significant increase in plasma volume that possibly contributed to the observed increase of aerobic fitness (MAP and MAS).

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John K. Malone, Catherine Blake and Brian Caulfield

Purpose:

To investigate the use of neuromuscular electrical stimulation (NMES) during acute recovery between 2 bouts of maximal aerobic exercise.

Methods:

On 3 separate days, 19 trained male cyclists (28 ± 7 y, 76.4 ± 10.4 kg, power output at maximal aerobic power [pVo2max] 417 ± 44 W) performed a 3-min maximal cycling bout at 105% PVo2max before a 30-min randomly assigned recovery intervention of passive (PAS: resting), active (ACT: 30% PVo2max), or NMES (5 Hz, 4 pulses at 500 μs). Immediately afterward, a cycle bout at 95% PVo2max to exhaustion (TLIM) was performed. Heart rate (HR) and blood lactate (BLa) were recorded at designated time points. Data were analyzed using repeated-measures ANOVA with a Tukey honestly significantly different post hoc test. Statistical significance threshold was P < .05.

Results:

The TLIM was significantly shorter for NMES than for ACT (199.6 ± 69.4 s vs 250.7 ± 105.5 s: P = .016) but not PAS recovery (199.6 ± 69.4 s vs 216.4 ± 77.5 s: P = .157). The TLIM was not significantly different between ACT and PAS (250.7 ± 105.5 s vs 216.4 ± 77.5 s: P = .088). The decline in BLa was significantly greater during ACT than NMES and PAS recovery (P < .001), with no difference between NMES and PAS. In addition, HR was significantly higher during ACT than NMES and PAS recovery (P < .001), with no difference between NMES and PAS.

Conclusions:

NMES was less effective than ACT and comparable to PAS recovery when used between 2 bouts of maximal aerobic exercise in trained male cyclists.

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Matthew D. Vukovich, Rick L. Sharp, Douglas S. King and Kellie Kershishnik

Eleven subjects performed a graded exercise test after 1 week of protein supplementation (PRO) or glucose polymer placebo (CON), randomly assigned in a double blind fashion. The exercise consisted of 3-min graded exercise bouts separated by 10 min of active recovery at zero pedal resistance. Subjects then performed a 30-sec Wingate test (WIN) to assess performance during supramaximal exercise. Blood samples were obtained in the last 15 sec of each exercise and recovery period. PRO resulted in a decrease in blood lactate following 120% VO2max and WIN, an increase in blood alanine at all time points, and lower postexercise muscle lactate and glycogen. Resting muscle GPT activity was 47% higher during the PRO trial. Mean power output during the WIN did not differ between PRO and CON. The WIN fatigue index was not significantly different between PRO and CON. The increased alanine may reflect increased transamination of pyruvate, thereby reducing the accumulation of lactate, which in turn had a marginal effect on performance during supramaximal exercise.