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Hassane Zouhal, Abderraouf Ben Abderrahman, Jacques Prioux, Beat Knechtle, Lotfi Bouguerra, Wiem Kebsi and Timothy D. Noakes

Purpose:

To determine the effect of drafting on running time, physiological response, and rating of perceived exertion (RPE) during 3000-m track running.

Methods:

Ten elite middle- and long-distance runners performed 3 track-running sessions. The 1st session determined maximal oxygen uptake and maximal aerobic speed using a lightweight ambulatory respiratory gasexchange system (K4B2). The 2nd and the 3rd tests consisted of nondrafting 3000-m running (3000-mND) and 3000-m running with drafting for the 1st 2000 m (3000-mD) performed on the track in a randomized counterbalanced order.

Results:

Performance during the 3000-mND (553.59 ± 22.15 s) was significantly slower (P < .05) than during the 3000-mD (544.74 ± 18.72 s). Cardiorespiratory responses were not significantly different between the trials. However, blood lactate concentration was significantly higher (P < .05) after the 3000-mND (16.4 ± 2.3 mmol/L) than after the 3000-mD (13.2 ± 5.6 mmol/L). Athletes perceived the 3000-mND as more strenuous than the 3000-mD (P < .05) (RPE = 16.1 ± 0.8 vs 13.1 ± 1.3). Results demonstrate that drafting has a significant effect on performance in highly trained runners.

Conclusion:

This effect could not be explained by a reduced energy expenditure or cardiorespiratory effort as a result of drafting. This raises the possibility that drafting may aid running performance by both physiological and nonphysiological (ie, psychological) effects.

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Gi Broman, Miguel Quintana, Margareta Engardt, Lennart Gullstrand, Eva Jansson and Lennart Kaijser

The aim of the study was to examine submaximal and maximal physiological responses and perceived exertion during deep-water running with a vest compared with the responses during treadmill running in healthy elderly women. Eleven healthy women 70 ± 2 years old participated. On two different occasions they performed a graded maximal exercise test on a treadmill on land and a graded maximal exercise test in water wearing a vest. At maximal work the oxygen uptake was 29% lower (p < .05), the heart rate was 8% lower (p < .05), and the ventilation was 16% lower (p < .05) during deep-water running than during treadmill running. During submaximal absolute work the heart rate was higher during deep-water running than during treadmill running for the elderly women. The participants had lower maximal oxygen uptake, heart rate, ventilation, respiratory-exchange ratio, and rate of perceived exertion during maximal deep-water running with a vest than during maximal treadmill running. These responses were, however, higher during submaximal deep-water running than during treadmill running.

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Naiandra Dittrich, Ricardo Dantas de Lucas, Ralph Beneke and Luiz Guilherme Antonacci Guglielmo

The purpose of this study was to determine and compare the time to exhaustion (TE) and the physiological responses at continuous and intermittent (ratio 5:1) maximal lactate steady state (MLSS) in well-trained runners. Ten athletes (32.7 ± 6.9 y, VO2max 61.7 ± 3.9 mL · kg−1 · min−1) performed an incremental treadmill test, three to five 30-min constant-speed tests to determine the MLSS continuous and intermittent (5 min of running, interspaced by 1 min of passive rest), and 2 randomized TE tests at such intensities. Two-way ANOVA with repeated measures was used to compare the changes in physiological variables during the TE tests and between continuous and intermittent exercise. The intermittent MLSS velocity (MLSSint = 15.26 ± 0.97 km/h) was higher than in the continuous model (MLSScon = 14.53 ± 0.93 km/h), while the TE at MLSScon was longer than MLSSint (68 ± 11 min and 58 ± 15 min, P < .05). Regarding the cardiorespiratory responses, VO2 and respiratory-exchange ratio remained stable during both TE tests while heart rate, ventilation, and rating of perceived exertion presented a significant increase in the last portion of the tests. The results showed a higher tolerance to exercising during MLSScon than during MLSSint in trained runners. Thus, the training volume of an extensive interval session (ratio 5:1) designed at MLSS intensity should take into consideration this higher speed at MLSS and also the lower TE than with continuous exercise.

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Mark Waldron and Aron Murphy

This study aimed to identify characteristics of match performance and physical ability that discriminate between elite and subelite under-14 soccer players. Players were assessed for closed performance and movement, physiological responses, and technical actions during matches. Elite players covered more total m·min−1 (115.7 ± 6.6 cf. 105.4 ± 7.7 m·min−1) and high-intensity m·min−1 (elite = 14.5 ± 2.3 cf. 11.5 ± 3.7 m·min−1) compared with subelite players. Elite players also attempted more successful (0.41 ± 0.11 cf. 0.18 ± 0.02) and unsuccessful ball retentions·min−1 (0.14 ± 0.04 cf. 0.06 ± 0.02) compared with subelite players. Elite players were faster over 10 m (1.9 ± 0.1 cf. 2.3 ± 0.2 s) and faster dribblers (16.4 ± 1.4 cf. 18.2 ± 1.1 s) compared with subelite players. Speed (10 m) and successful ball retention·min−1 contributed to a predictive model, explaining 96.8% of the between-group variance. The analysis of match performance provides a more thorough understanding of the factors underlying talent among youth soccer players.

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L. Christopher Eschbach, Michael J. Webster, Joseph C. Boyd, Patrick D. McArthur and Tammy K. Evetovich

It has been suggested that Eleutherococcus senticosus (ES). also known as Siberian ginseng or ciwuija. increases fat utilization in humans. The purpose of this study was to examine the physiological responses to supplementation with ES in endurance cyclists. Using arandomized. double-blind crossover design. 9 highly-trained men (28 ± 2 years. V̇O2max 57.3±2.0 ml · kg−1 · min−1) cycled for 120 min at 60% V̇O2max followed by a simulated 10-km lime trial. Diet was controlled, and ES (1,200 mg · day−1) or a placebo (P) were administered for 7 days prior to each of the two trials. Oxygen consumption, respiratory exchange ratio, and heart rate were recorded every 30 min, and rating of perceived exertion. plasma [lactate], and plasma [glucose j were recorded every 20 min during the 120 min of steady state cycling. There were no significant differences (p > .05) between the ES and P groups at any steady-state time interval or during the cycling time trial (ES = 18.10 ± 0.42, P = 17.83 ± 0.47 min). In contrast with previous reports, the results of this study suggest that ES supplementation does not alter steady-state substrate utilization or 10-km cycling performance time.

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Jon L. Oliver, Neil Armstrong and Craig A. Williams

Purpose:

The purpose of the study was to assess the reliability and validity of a newly developed laboratory protocol to measure prolonged repeated-sprint ability (RSA) during soccer-specific exercise.

Methods:

To assess reliability, 12 youth soccer players age 15.2 ± 0.3 y performed 2 trials of a soccer-specific intermittent-exercise test (SSIET) separated by 3 months. The test was performed on a nonmotorized treadmill. A separate sample of 12 youth soccer players (15.2 ± 0.3 y) completed the SSIET while simultaneously HR, VO2, and blood lactate (BLa) were monitored. The SSIET was designed to replicate the demands of competing in one half of a soccer match while sprint performance was monitored. The test included a 5-s sprint every 2 min.

Results:

The mean coefficient of variation was 2.5% for the total distance covered during the SSIET and 3.8% for the total distance sprinted; measures of power output were less reliable (>5.9%). Participants covered 4851 ± 251 m during the SSIET, working at an average intensity of 87.5% ± 3.2% HRpeak and 70.2% ± 3.1% VO2peak, with ~7mmol/L BLa accumulation. A significant reduction (P < .05) in sprint performance was ob served over the course of the SSIET.

Conclusion:

The SSIET provided a reliable method of assessing prolonged RSA in the laboratory. The distance covered and the physiological responses during the SSIET successfully recreated the demands of competing in a soccer match.

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Thomas Losnegard, Martin Andersen, Matt Spencer and Jostein Hallén

Purpose:

To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing.

Methods:

Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods.

Results:

The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol.

Conclusions:

Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.

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Olivier Rey, Jean-Marc Vallier, Caroline Nicol, Charles-Symphorien Mercier and Christophe Maïano

Purpose:

This study examined the effects of a five-week intervention combining vigorous interval training (VIT) with diet among twenty-four obese adolescents. Fourteen girls and ten boys (aged 14–15) schooled in a pediatric rehabilitation center participated.

Methods:

The VIT intensity was targeted and remained above 80% of maximal heart rate (HR) and over six kilocalories per minute. Pre- and postintervention measures were body composition (BMI, weight, body fat percentage), physical self-perceptions (PSP), physical fitness (6-min walking distance and work) and its associated physiological responses (HRpeak and blood lactate concentration). A series of two-way analyses of variance or covariance controlling for weight loss were used to examine the changes.

Results:

Significant improvements were found in body composition, physical fitness and PSP (endurance, activity level, sport competence, global physical self-concept and appearance). In addition, boys presented higher levels of perceived strength and global physical self-concept than girls. Finally, there was a significant increase in perceived endurance, sport competence, and global physical self-concept in girls only.

Conclusion:

This five-week VIT program combined with diet represents an effective means for improving body composition, physical fitness, and PSP in obese adolescents, the effects on PSP being larger among girls.

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Claire Rechichi, Brian Dawson and Carmel Goodman

Some reports suggest variation in physiological responses and athletic performance, for female athletes at specific phases of the menstrual cycle. However, inconsistent findings are common due to the inappropriate verification of menstrual cycle phase, small subject numbers, high intra- and interindividual variability in estrogen and progesterone concentration, and the pulsatile secretion of these hormones. Therefore, the oral contraceptive (OC) cycle may provide a more stable environment in which to evaluate the acute effect of reproductive hormones on physiological variables and exercise performance. To date, most of the OC research has compared differences between OC use and nonuse, and few researchers have examined within-cycle effects of the OC. It is also apparent that OC use is becoming far more prevalent in athletes; hence the effect of the different exogenous and endogenous hormonal profiles on athletic performance should be investigated. Research to date identifies potential for variation in aerobic performance, anaerobic capacity, anaerobic power and reactive strength throughout an OC cycle. The purpose of this review is to present and evaluate the current literature on the physiology of exercise and athletic performance during the OC cycle.

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W. Jack Rejeski, Edward Gregg, Amy Thompson and Michael Berry

In this investigation, we examined the role of acute aerobic exercise (AE) in buffering physiological responses to mental stress. Twelve trained cyclists participated in three counterbalanced treatment conditions on separate days: attention control, light exercise (50% of VO2max for 30 min), and heavy exercise (80% of VO2max for 60 min). After a 30-min rest period following each condition, subjects completed a modified Stroop task. Blood pressure (BP) and heart rate (HR) were monitored for (a) baseline responses, (b) task reactivity, and (c), 5 min of recovery following the stressor. Mean arterial pressure (MAP) revealed that reactivity was attenuated by both heavy- and light-exercise conditions as compared to responses in the control condition. Moreover, heavy exercise was more effective in reducing MAP reactivity than light exercise. Systolic BP during the task was significantly higher in the control and light-exercise conditions than following heavy exercise; diastolic BP was significantly higher in the control condition than in either exercise condition. There were no significant effects for HR. These results suggest that there is a dose-response relationship between acute AE and the attenuation of psychophysiological reactivity during stress.