This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min−1·kg−1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.
Florian Engel, Sascha Härtel, Jana Strahler, Matthias Oliver Wagner, Klaus Bös and Billy Sperlich
Hassane Zouhal, Abderraouf Ben Abderrahman, Jacques Prioux, Beat Knechtle, Lotfi Bouguerra, Wiem Kebsi and Timothy D. Noakes
To determine the effect of drafting on running time, physiological response, and rating of perceived exertion (RPE) during 3000-m track running.
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.
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.
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.
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.
Mindy Millard-Stafford, Linda B. Rosskopf, Teresa K. Snow and Bryan T. Hinson
Twelve highly trained male runners ran 15 km at self-selected pace on a treadmill in warm conditions to demonstrate differences in physiological responses, fluid preferences, and performance when ingesting sports drinks or plain water before and during exercise. One hour prior to the start of running, an equal volume (1,000 ml) of either water or a 6% or an 8% carbohydrate-electrolyte (CE) drink was ingested. Blood glucose was significantly higher 30 min following ingestion of 6% and 8% CE compared to water, significantly lower at 60 min postingestion with both sports drinks than with water, but similar after 7.5 km of the run for all beverages. During the first 13.4 km, oxygen uptake and run times were not different between trials; however, the final 1.6-km performance run was faster with both CE drinks compared to water. Despite a lower preexercise blood glucose, CE consumption prior to and during exercise significantly improved performance in the last 1.6 km of a 15-km run compared to water.
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.
Thomas Losnegard, Martin Andersen, Matt Spencer and Jostein Hallén
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.
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.
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.
Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.
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.
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.
Andrew C. Morris, Ira Jacobs, Tom M. McLellan, Abbey Klugerman, Lawrence C.H. Wang and Jiri Zamecnik
The purpose of this study was to examine the effects of ginseng extract ingestion on physiological responses to intense exercise. Subjects performed a control ride (CN) on a cycle ergometer, followed by placebo (PL) and ginseng (GS) treatments. Ginseng was ingested as 8 or 16 mg/kg body weight daily for 7 days prior to trial GS. Venous blood was sampled for FFA, lactate, and glucose analyses. Due to similar findings for both dose groups, the subjects were considered as one group. Lactate, FFA,
Jennifer K. Ormerod, Tabatha A. Elliott, Timothy P. Scheett, Jaci L. VanHeest, Lawrence E. Armstrong and Carl M. Maresh
The purposes of this study were to characterize measures of fluid intake and perception of thirst in women over a 6-week period of exercise-heat acclimation and outdoor training and examine if this lengthy acclimation period would result in changes in fluid intake that differ from those previously reported in men utilizing a shorter acclimation protocol of 8–10 days. Voluntary water intake (11–17 °C) and perception of thirst were measured in a group of 5 women (21–26 yr) undergoing exercise-heat acclimation for 90 min/day, 3 days/wk (36 °C, rh 50–70%) and outdoor training 3 days/wk for 6 weeks. Decreased drinking during acclimation was characterized by a decrease in the number of drinks (35 ± 10 to 17 ± 5; p < .05), greater time to first drink (9.9 ± 2.0 to 23.1 ± 4.7 min; p < .05), and a decrease in total volume ingested per week (3310 ± 810 to 1849 ± 446 ml; p < .05) through the 6-week study. Mean perceived thirst measurements remained low and showed only slight variance (3 ± 0.4 to 5 ± 0.4). These observations support a psycho-physiological response pattern different than that previously observed during 8–10 day acclimation protocols in men.