Respiratory responses and rating of perceived exertion of severely obese adolescents during continuous and intermittent graded walking protocols: Application to cardiorespiratory field tests.

During 20 m shuttle tests, obese adolescents may have difficulty achieving maximum cardiorespiratory performance due to the presence of braking-relaunch phases (BRP). Nineteen obese adolescents aged 15.2 ± 1.5 years (body mass index [BMI] = 39.7 ± 5.9 kg.m-2) performed three graded walking exercises on a 50 m track at speeds between 3 and 6 km/h: a continuous-straight-line protocol (C), a continuous protocol that required turning back every 30 sec (C-BRP) and an intermittent protocol that consisted of successively walking then resting for 15 sec (15-15). Oxygen uptake (VO2), aerobic cost of walking (Cw), ventilation (VE) and rating of perceived exertion (RPE) were measured at each stage during the protocols. During C-BRP, the responses were not significantly higher compared with C (p > 0.30). During 15-15, the VO2, Cw and VE were ~ 15 to 25% lower than during C beginning at 4 km/h (p < 0.05). In obese adolescents, the respiratory impact of sudden directional changes during the 20 m shuttle-type test appeared to be minor at walking speeds. During the 15-15 test, the intensity increases more progressively, and this design may encourage obese adolescents to walk further than during a continuous test.

BDNF, IGF-I, Glucose and Insulin during Continuous and Interval Exercise in Type 1 Diabetes.

Type 1 diabetes (T1D) can have a significant impact on brain function, mostly ascribed to episodes of hypoglycemia and chronic hyperglycemia. Exercise has positive effects on acute and chronic glycemic control in T1D, and has beneficial effects on cognitive function by increasing neurotrophins such as BDNF and IGF-I in non-diabetic humans. The present study examines the effects of different types of exercise intensities on neurotrophins in T1D. 10 participants with type 1 diabetes were evaluated in 3 sessions: high-intensity exercise (10×[60 s 90%Wmax, 60 s 50 W]), continuous exercise (22 min, 70% VO2 max) and a control session. Blood glucose, serum free insulin, serum BDNF and IGF-I were assessed pre/post all the trials and after recovery. Blood glucose significantly decreased after both exercise intensities and BDNF levels increased, with a dose-response effect for exercise intensity on BDNF. IGF-I changed over time, but without a difference between the different exercise protocols. Both exercise intensities change neurotrophins in T1D, but also exhibit a dose response effect for BDNF. The intensity-dependent findings may aid in designing exercise prescriptions for maintaining or improving neurological health in T1D, but both types of exercise can be implemented.

Faster pulmonary oxygen uptake kinetics in children vs adults due to enhancements in oxygen delivery and extraction.

This study aimed to examine if the faster pulmonary oxygen uptake (VO2p) phase 2 in children could be explained by increased O2 availability or extraction at the muscle level. For that purpose, O2 availability and extraction were assessed using deoxyhemoglobin (HHb) estimated by near-infrared spectroscopy during moderate-intensity constant load cycling exercise in children and young adults. Eleven prepubertal boys and 12 men volunteered to participate in the study. They performed one maximal graded exercise to determine the power associated with the gas exchange threshold (GET) and four constant load exercises at 90% of GET. VO2p and HHb were continuously monitored. VO2p , HHb, and estimated capillary blood flow (Qcap) kinetics were modelled after a time delay and characterized by the time to achieve 63% of the amplitude (τ) and by mean response time (MRT: time delay + τ), respectively. Mean values of τ for VO2p (P < 0.001), of MRT for HHb (P < 0.01) and of MRT for Qcap (P < 0.001) were significantly shorter in children. Faster VO2p kinetics have been shown in children; these appear due to both faster O2 extraction and delivery kinetics as indicated by faster HHb and Qcap kinetics, respectively.

Recovery after an intermittent test.

The purpose of this study was to analyse the impact of an intermittent test reproducing the soccer running activity profile on physical performance, subjective ratings and biochemical parameters throughout 72 h recovery. 8 professional soccer players performed the intermittent test on a non-motorised treadmill and data was collected before, immediately after, 24, 48 and 72 h after the test. Squat jump (SJ), countermovement jump (CMJ), peak isometric force (IFpeak), 6-s sprint, repeated sprints test (RS), perceptual ratings (fatigue, muscle soreness, stress), creatine kinase ([CK]) and uric acid ([UA]) were analyzed. After the test, a mean reduction in countermovement jump performance of -8.2% (CI: -12.9 to -3.4, p<0.01) was observed, while perceived fatigue (+2.1±1.7 a.u.; p<0.05), perceived muscle soreness (+1.8±1.5 a.u.; p<0.05), perceived stress (+1.6±1.5 a.u.; p<0.05), creatine kinase (+171±77 IU x l(-1); p<0.01) and uric acid (+168±89 Umol x l(-1); p<0.01) concentrations were significantly increased relative to baseline. No significant effect was found for SJ, IFpeak, 6-s sprint, RS immediately after and throughout the 72 h following the test. In conclusion, soccer running performance does not appear to be the main cause of post soccer match-induced fatigue. Physical data provided by video match analysis systems is insufficient to accurately estimate the level of match fatigue.

Two months of endurance training does not alter diastolic function evaluated by TDI in 9-11-year-old boys and girls.

OBJECTIVE: Superior global cardiac performance (ie stroke volume) is classically reported after training in children. Current knowledge of the impact of exercise training on myocardial relaxation, a major component of left ventricular (LV) filling and subsequently stroke volume, is, however, limited in the paediatric population. This study aimed to investigate the effect of aerobic training on LV wall motion velocities by tissue Doppler imaging (TDI) in healthy children. METHODS: 25 children (11 girls, 14 boys) were enrolled in a 2 month high-intensity aerobic training programme and 25 (12 girls and 13 boys) served as controls. The children (9-11 years old) performed a graded maximal exercise test on a treadmill to evaluate maximal oxygen uptake. Standard Doppler echocardiography and TDI measurements were performed at baseline and end of the study. Tissue Doppler systolic, early and late myocardial velocities were obtained at the mitral annulus in the septal, lateral, inferior and posterior walls. RESULTS: Maximal oxygen uptake increased by 6.5% (before: 51.6 (SD 4.2), after: 55.0 (4.5) ml/min/kg p<0.001) after training. A modest but significant increase in left ventricular end-diastolic diameter was also noticed (before: 46.1 (3.4), after: 48.3 (4.3) mm.BSA(-1/2), p<0.001), whereas left ventricular wall thickness and mass were unchanged. Neither transmitral inflow velocities nor early and late wall motion (Em: before = 18.4 (2.7), after = 18.0 (2.3) cm/s, Am: before = 6.8 (1.2), after = 6.7 (1.3) cm/s) were affected by training. Shortening fraction and regional systolic function (Sm: before = 10.1 (1.6), after = 10.2 (1.4) cm/s) by TDI were also unchanged. CONCLUSION: High-intensity aerobic sessions repeated over a 2 month period failed to improve regional diastolic function assessed by TDI in healthy young children.

[One-leg cycling aerobic training with the healthy leg in amateur soccer players after anterior cruciate ligament reconstruction]. / Entraînement en endurance à partir du membre inférieur sain chez des footballeurs amateurs opérés de ligamentoplastie de genou.

OBJECTIVE: To examine cardiorespiratory fitness changes in subjects having undergone knee surgery and to assess the benefits of one-leg cycling aerobic training program during the rehabilitation period. METHOD: Two groups of 12 patients took part in this study. The control group profited from a five weeks conventional rehabilitation in day hospital without cardiorespiratory training. The second group profited in supplement from a one-leg cycling aerobic training program with the valid leg. The subjects were trained for 21 min, by alternating 3 min at 70% and 3 min at 85% of VO(2 peak). They totaled 15 sessions spread over five weeks. The initial evaluation (T1) is carried out the first day of rehabilitation and the final evaluation (T2) at a distance within 35 days. The evaluation consisted in realizing a maximal graded tests starting from the valid leg. RESULTS: After five weeks of conventional rehabilitation, we record a reduction of peak power output (W(peak)), peak oxygen uptake (VO(2 peak)) and peak minute ventilation (VE(peak)), respectively of 11, 12 and 13% for the control group. On the other hand, in T2, the training group has on average identical maximum values and some of them increased (W(peak): +14%; VE(peak): +15%). The first and second ventilatory thresholds appear with higher intensities of exercises. CONCLUSION: After knee surgery, conventional rehabilitation does not limit cardiorespiratory deconditioning. One leg cycling appears to be an adapted method to stop the effects of hypoactivity.

Validity of the polar S810 to measure R-R intervals in children.

Intervals between two consecutive cardiac beats (R-R intervals) and the subsequent analysis of heart rate variability (HRV) obtained simultaneously from the Polar S810 heart rate monitor (HRM) and an electrocardiogram (ECG) in a supine position were compared in twelve children (age 9.6 +/- 0.9 years) before and after protocol correction. R-R intervals were significantly different between the ECG and the HRM uncorrected and corrected signal (p < 0.001, effect size [ES] = 0.005, and 0.005, respectively). However, the bias (95 % confidence interval) was 0.80 (- 124.76 - 123.16) ms and 0.80 (- 12.76 - 11.16) ms, respectively. HRV parameters derived from both signals were not different (p > 0.05) and well correlated (r > 0.99, p < 0.05), except SD2 (p < 0.05, ES = 0.000; r = 0.99). These data support the validity of the Polar S810 HRM to measure R-R intervals and make the subsequent HRV analysis in a supine position in children.

Reliability of postexercise heart rate recovery.

Passive postexercise heart rate (HR) recovery is currently used in the assessment of endurance athletes to determine changes in performance or in the clinical setting as a predictor of all-cause mortality. The purpose of this investigation was to assess the reliability of HR recovery. Thirty healthy subjects performed two maximal and two submaximal treadmill exercises, followed by 5 minutes of passive recovery. HR signal was used to compute raw and Delta (exercise - recovery) HR after 1, 2, 3, and 5 minutes of exercise cessation. A mono-exponential function was fitted to the data using the least squares procedure. We found no significant bias between repeated measures. Relative reliability was lower for Delta HR when compared with raw HR (0.43 < ICC < 0.71 vs. 0.68 < ICC < 0.83, respectively). Absolute reliability was relatively constant over time for raw HR (SEM = approximately 8 %), while it decreased exponentially from the 1st (SEM = approximately 20 %) to the 5th minute of recovery (SEM = approximately 8 %) for Delta HR. The reliability of parameter estimates from exponential curve fitting was less consistent, since both ICC (0.43 to 0.88) and SEM (5.7 to 21.4 %) differed from one parameter to the other according to the intensity of exercise. We conclude that passive postexercise HR recovery reliability is heterogeneous. Raw HR is the desired method to describe it.

Effect of training and detraining on heart rate variability in healthy young men.

The purpose of this study was to investigate the effect of twelve weeks of aerobic training and eight weeks of training cessation on Heart Rate Variability (HRV). Ten healthy young men (Age: 21.7 +/- 2.2 years; Height: 179.2 +/- 6.9 cm; Mass 72.7 +/- 11.1 kg) completed an incremental test and a 60 degrees tilt test during which R-R intervals were recorded before (T0) and after (T12) 12 weeks of intensive training, and after 2, 4 and 8 weeks of training cessation (D2, D4 and D8, respectively). HRV was computed in time and frequency domains. Training resulted in a significant increase in estimated VO2max after T12 (p < 0.01), followed by a significant decrease during D2 and D8 (p < 0.05). Total power (LF + HF) and low frequency power (LF) increased significantly in the supine position after the training period (p < 0.05) and decreased moderately after D2 (p > 0.05) to stabilize afterwards. LF + HF and LF were not different from T0 at D8 (p > 0.05). It was concluded that eight weeks of training cessation allow to reverse the cardiovascular autonomic adaptations induced by 12 weeks of intensive training in healthy young men.

[Preliminary study of cardiorespiratory decondittioning in athletes after anterior cruciate ligament reconstruction]. / Etude préliminaire de la désadaptation cardiorespiratoire après une ligamentoplastie de genou chez le sportif.

AIM: The aim of this study was to analyze changes in cardiorespiratory fitness of athletes who had surgery following a lesion of the anterior cruciate ligament of the knee. METHODS: Two groups of 12 athletes at the regional level underwent surgical repair to rebuild the external anterior crossed ligament of the knee (central third bone patellar tendon bone autograft and doubled semitendinosus/doubled gracilis autograft techniques). All subjects were evaluated before and after surgery within 7 days: the first group underwent maximal incremental tests with the upper limbs, and the second group measurement of resting cardiac volumes. RESULTS: Surgery followed by a few days of confinement generated a quick and significant reduction in the maximal oxygen consumption (-7%, P<0.05) and peak aerobic power (-8%, P<0.05). End diastolic volume and stroke volume were reduced, by 23% and 27% respectively (P<0.05). A significant reduction of ejection fraction was also observed (P<0.05). The mean left ventricular ejection fraction was 65% before the surgery 60% after 7 days' of hospitalization. CONCLUSION: In sportsmen, 7 days of hospitalization due to surgery of the knee led to resting cardiac unsuitability characterized by a significant reduction in the stroke volume. These elements could involve decreased aerobic fitness and should encourage the hospital practitioner to propose a program of aerobic training in addition to conventional rehabilitation.

Longitudinal follow-up of fitness during childhood: interaction with physical activity.

Health-related fitness values during childhood (from age 11 to 16 years) were analyzed in relation to changes in physical activity level. One hundred fifty-eight children were monitored over a 4-year period. Twice a year, they performed six physical fitness tests: standing broad jump, 10 x 5-meter shuttle run, sit-and-reach, handgrip, number of sit-ups in 30 s, and 20-m shuttle run. Height was measured four times per year to assess age at peak height velocity. Physical activity was assessed with a self-administered questionnaire at baseline and at the end of the follow-up. The physical activity level was defined by the frequency and the time spent in moderate-to-vigorous physical activities. Two groups were constituted: regularly active and sedentary. A multiple linear multilevel regression analysis was used to analyze the longitudinal relationships between changes in physical activity and physical fitness levels. Corrections were made for both time-dependent (time) and time-independent (sex) variables. Except for flexibility, boys' fitness performances increased more than that for the girls. Positive and significant (P < 0.05) regression coefficients were found with the regularly active for standing broad jump, 20-m shuttle run, number of sit-ups, 10 x 5-m shuttle run in both sexes, and for the girls' sit-and-reach performance. Increasing or decreasing physical activity level was not associated with changes in fitness performances over time, except for flexibility for the girls and the 20-m shuttle run for the boys. From childhood to adolescence, increasing physical activity is not sufficient to be more fit. The children who are stayed the most active were the fittest, particularly the girls. Am. J. Hum. Biol. 18:51-58, 2006. (c) 2005 Wiley-Liss, Inc.

Respiratory muscle deoxygenation and ventilatory threshold assessments using near infrared spectroscopy in children.

The aim of this study was to assess respiratory muscles deoxygenation and to determine ventilatory threshold using near infrared spectroscopy (NIRS) in children during incremental cardiopulmonary exercise. Fourteen healthy children with a mean +/- SD age of 12.8 +/- 1.4 yrs performed an incremental exercise test on a cycle ergometer. NIRS was used to assess deoxygenation of the respiratory muscles. Ventilatory parameters (oxygen uptake, carbon dioxide production, and ventilation minute), power output, and tissue saturation (StO2) were measured. Ventilatory threshold was determined by the two following methods: the V-slope method which corresponds to the breakpoint in VCO2 as a function VO2 relationship (VT(V-slope)) and the NIRS method which corresponds to the point of rapid fall in StO2 (VT(nirs)). During exercise, the respiratory muscles deoxygenated as the exercise intensity increased. StO2 decrease progressively until an abrupt decrease was observed. No significant differences were observed between cardiorespiratory variables corresponding either to VT(V-slope) or to VT(nirs). The two methods showed a good agreement (data were inside the 95 % confidence interval). Likewise, a significant relationship was found between VT(V-slope) and VT(nirs) for each parameter measured (r = 0.87 to 0.94, p < 0.001). We concluded that respiratory muscles deoxygenate during incremental exercise in children and that ventilatory threshold could be determined by NIRS.

Evidence of exercise-induced O2 arterial desaturation in non-elite sportsmen and sportswomen following high-intensity interval-training.

The aim of this study was to investigate the development of exercise-induced hypoxemia (EIH defined as an exercise decrease > 4 % in oxygen arterial saturation, i. e. SaO (2) measured with a portable pulse oximeter) in twelve sportsmen and ten sportswomen (18.5 +/- 0.5 years) who were non-elite and not initially engaged in endurance sport or training. They followed a high-intensity interval-training program to improve V.O (2)max for eight weeks. The training running speeds were set at approximately 140 % V.O (2)max running speed up to 100 % 20-m maximal running speed. Pre- and post-training pulmonary gas exchanges and SaO (2) were measured during an incremental running field-test. After the training period, men and women increased their V.O (2)max (p < 0.001) by 10.0 % and 7.8 %, respectively. Nine subjects (seven men and two women) developed EIH. This phenomenon appeared even in sportsmen with low V.O (2)max from 45 ml x min (-1) x kg (-1) and seemed to be associated with inadequate hyperventilation induced by training: because only this hypoxemic group showed 1) a decrease in maximal ventilatory equivalent in O (2) (V.E/V.O (2), p < 0.01) although maximal ventilation increased (p < 0.01) with training, i. e. in EIH-subjects the ventilatory response increased less than the metabolic demand after the training program; 2) a significant relationship between SaO (2) at maximal workload and the matched V.E/V.O (2) (p < 0.05, r = 0.67) which strengthened a relative hypoventilation implication in EIH. In conclusion, in this field investigation the significant decrease in the minimum SaO (2) inducing the development of EIH after high-intensity interval-training indicates that changes in training conditions could be accompanied in approximately 40 % non-endurance sportive subjects by alterations in the degree of arterial oxyhemoglobin desaturation developing during exercise.

High-intensity intermittent activities at school: controversies and facts.

In comparison to continuous aerobic type activity, little is known about high-intensity intermittent physical activity in children. Repeated short-term high-intensity activities (> maximal aerobic speed and <10 s) are more characteristic of the spontaneous physical activity of children. Recent studies have shown during repetitive bouts of sprints separated by short recovery intervals, that prepubescent children compared with adults are more able to maintain their performance without substantial fatigue. Moreover, repetitive runs at high velocities (near and higher than the maximal aerobic speed) separated by short recovery periods may elicit a high oxygen consumption in children. Several studies using interval training programmes for 7 weeks, twice a week for 30 min in physical education lessons showed that children's aerobic performance (maximal O2 uptake, maximal aerobic speed) could be enhanced. Training based on these repeated short-term high-intensity exercises could also improve children's anaerobic performance (short-term muscle power, strength and speed). Current evidence suggests that recovery from high-intensity exercises is faster in children than in adults and that repeated runs at high velocities separated by short recovery intervals can improve both aerobic and anaerobic performance. Although continuous aerobic type activity is more scientifically established as a training mode, repeated short-term high-intensity exercises in physical education programmes should be considered to enhance aerobic, as well as, anaerobic fitness in children.

Time spent at VO2max: a methodological issue.

This study was designed to propose a standardised procedure to determine the time spent at VO2max (tVO2max) based on the VO2max of the day (i. e. the VO2max value measured the day of the test). Ten male subjects first performed a graded field test, followed by a continuous running exercise to exhaustion, at the velocity of the Université de Montréal Track Test (V(UMTT)) plus 1 km x h(-1) (V(UMTT)(+1)). The second test consisted of an exhaustive run at 100 % of V(UMTT), followed by a V(UMTT)(+1) test. Different methods were used to compare time spent at VO2max, based on the VO2max of the graded field test, and time spent at VO2max, based on the VO2max of the day, during an exhaustive run at 100 % of V(UMTT). Results have shown that V(UMTT)(+1) tests were of sufficient intensity and duration to identify the VO2max of the day. Time spent at VO2max ranged from 25 +/- 53 s to 139 +/- 76 s according to the method used. However, the tVO2max method based on the sum of each value higher than 95 % of VO2max of the day appeared more robust than methods based on the time to exhaustion minus time to reach VO2 reference value, or the method based on the sum of values higher than VO2max minus 2.1 ml x kg(-1) x min(-1).

Plasma lactate and plasma volume recovery in adults and children following high-intensity exercises.

AIM: To compare plasma lactate concentration recovery kinetics when measured and corrected for variations in plasma volume between children and adults. METHODS: Nine boys (11.3 +/- 1.1 y) and 8 men (21.9 +/- 1.9 y) performed a maximal and a supramaximal exercise until exhaustion. Plasma lactate concentrations, haemoglobin and haematocrit were measured at rest, immediately on completion of exercise and after the 2nd, 5th, 12th and 30th minute of recovery. The plasma lactate concentrations and the rate of recovery were corrected for variations in plasma volume. RESULTS: The maximal decreases in plasma volume were significantly higher in adults than in children for maximal exercise (-18.7 +/- 2.6% vs -14.5 +/- 3.2%; p < 0.05), but similar for the supramaximal exercise (-16.9 +/- 3.4% vs -15.2 +/- 3.4%). During recovery, measured and corrected plasma lactate concentrations were significantly higher in adults. The rate of plasma lactate recovery was higher in adults for maximal exercise only. The same results were obtained when the rates of plasma lactate decrease were calculated from corrected plasma lactate concentrations. CONCLUSION: The correction of the plasma lactate concentrations for variations in plasma volume did not influence the comparison of the concentrations obtained in adults and children, or their rate of recovery.

Effects of high intensity intermittent training on peak VO(2) in prepubertal children.

This study was designed to examine peak VO(2) responses of prepubescent children following a 7-week aerobic training. Twenty-three boys and thirty girls (9.7 +/- 0.8 years) were divided into a high intensity experimental group (HIEG: 20 girls and 13 boys) and a control group (CG: 10 girls and 10 boys). A graded 20-m shuttle run with measurement of gas exchange values was performed prior to and after the 7-week training program. The test consisted of a 3-min run at 7 km x h(-1) to determine energy cost of running, immediately followed by a 20-meter shuttle run test. HIEG had two 30 min-sessions of short intermittent aerobic training per week at velocities ranging from 100 up to 130 % of the maximal aerobic speed. For HIEG, absolute peak VO(2)(9.1 %) and relative to body mass peak VO(2)(8.2 %) increased significantly (p < 0.001); it was unchanged in the CG. Similarly, maximal shuttle run improved significantly in HIEG (5.1 %, p < 0.001). In contrast, there was no significant change for CG. For both groups energy cost of running remained unchanged. These findings show that prepubescent children could significantly increase their peak VO(2) and maximal shuttle velocity with high intensity short intermittent aerobic exercises.

Plasma lactate recovery from maximal exercise with correction for variations in plasma volume.

BACKGROUND: To compare plasma lactate concentrations and plasma lactate kinetics during recovery, for measured and corrected values for changes in plasma volume, after a maximal aerobic exercise. METHODS: Sixteen male subjects performed an incremental and maximal exercise in order to reach maximal aerobic power. Prior to the exercise, at the end and during recovery (2, 5, 12 and 30 min), blood samples were collected through an antecubital catheter. Samples were analysed for lactate, hematocrit and hemoglobin in order to calculate changes in plasma volume. Plasma lactate concentrations ([La]p) were corrected for changes in plasma volume. Plasma lactate kinetics was estimated through the ratio between [La]p after 5 min recovery minus [La]p after 30 min to time (25 min) and expressed in percentage per minute. RESULTS: Maximal changes in plasma volume (-19.7 +/- 3.8%) were correlated to maximal measured [La]p (r=0.66, p<0.01). Maximal measured [La]p values (14.9 +/- 2.6 mmol x l-1) were 17.3% higher (p<0.001) than corrected values (12.7 +/-2.0 mmol x l-1). The kinetics of [La]p decrease was significantly higher (p<0.001) for measured values (2.38 +/- 0.29 % x min-1) than for corrected values (2.22 +/- 0.33 % x min-1). CONCLUSIONS: These results suggested that changes in plasma volume must be taken into account when peak postexercise plasma lactate concentration or lactate recovery curves are analysed.

Predicting sprint kinematic parameters from anaerobic field tests in physical education students.

The relations among kinematic parameters measured during the first 10 seconds of 100-m sprint and anaerobic tests were studied in 22 male physical education students. During the first 10 seconds of the sprint, the position of the runners was "continuously" measured with a laser telemeter. Maximal acceleration (Amax), maximal velocity (Vmax), and time to reach Vmax (tVmax) were derived from position data. In addition, the subjects performed anaerobic tests: squat jump (SJ), countermovement jump (CMJ), and force-velocity test to measure maximal power, maximal theoretical cranking velocity (VO), maximal theoretical isometric force, and the Wingate anaerobic test (30 seconds). The mean 100-m run time of the subjects was 12.6 +/- 0.9 seconds. The highest correlations were calculated between Amax and V0 (r = 0.55, p < 0.01) and CMJ (r = 0.48, p < 0.05) and Vmax and SJ (r = 0.63, p < 0.01) and CMJ (r = 0.56, p < 0.05). The tVmax was uncorrelated to other tests. Because the CMJ was the anaerobic performance best correlated to the different kinematic parameters of the run, our results fail to identify one anaerobic test that specifically explains one sprint kinematic parameter.

High-intensity aerobic training during a 10 week one-hour physical education cycle: effects on physical fitness of adolescents aged 11 to 16.

The aim of this study was to analyse the effects of a high-intensity aerobic training program on different components of physical fitness in adolescents aged 11 to 16 years. The subjects were divided into a high intensity (HI) group (243 girls and 260 boys) and a control (C) group (21 girls and 27 boys). HI and C completed a weekly 3 hour physical education (PE) session. Before and after a 10-week period, the two groups performed the European physical fitness test battery (EUROFIT). During these 10 weeks HI spent one hour out of three at a specific PE session. These specific sessions consisted of short intermittent exercises (10 seconds) at 100 to 120% of maximal aerobic speed. They showed a significant influence on standing broad jump (2.9 %, P<0.05, F=4.85), 20 meter shuttle run (3.8%, p0.001, F=23.21) and on the maximal distance covered over 7 min (7.6 %, P< 0.001, F= 14.48). For C there was no improvement in EUROFIT performances. It was concluded that training at high intensity improves not only children's aerobic fitness but also performance of standing broad jump. Well-monitored, adequate intensive training is necessary for a more desirable functional development.