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Hill R.,HP Sports and YSC Sports | Simpson B.,ASPIRE Academy for Sports Excellence | Manning J.,University of Swansea | Kilduff L.,University of Swansea
Journal of Sports Sciences | Year: 2012

A low digit ratio (2D:4D) and low 2D: 4D in the right compared with the left hand (right-left 2D:4D) are thought to be determined by high in utero concentrations of testosterone, and are related to ''masculine'' traits such as aggression and performance in sports like running and rugby. Low right-left 2D:4D is also related to sensitivity to testosterone as measured by the number of cytosine-adenine-guanine triplet repeats in exon 1 of the androgen receptor gene. Here we show that low right-left 2D:4D is associated with high maximal oxygen uptake (VO 2max), high velocity at VO 2max, and high maximum lactate concentration in a sample of teenage boys. We suggest that low right-left 2D:4D is linked to performance in some sports because it is a proxy of high sensitivity to prenatal and maybe also circulating testosterone and high VO 2max. © 2012 Taylor & Francis.


Mendiguchia J.,Rehab and Performance Center | Samozino P.,University of Savoy | Martinez-Ruiz E.,San Antonio de Murcia Catholic University | Brughelli M.,Auckland University of Technology | And 3 more authors.
International Journal of Sports Medicine | Year: 2014

The objectives of this study were to examine the consequences of an acute hamstring injury on performance and mechanical properties of sprint-running at the time of returning to sports and after the subsequent ~2 months of regular soccer training after return. 28 semi-professional male soccer players, 14 with a recent history of unilateral hamstring injury and 14 without prior injury, participated in the study. All players performed two 50-m maximal sprints when cleared to return to play (Test 1), and 11 injured players performed the same sprint test about 2 months after returning to play (Test 2). Sprint performance (i.e., speed) was measured via a radar gun and used to derive linear horizontal force-velocity relationships from which the following variables obtained: theoretical maximal velocity (V0), horizontal force (FH0) and horizontal power (Pmax). Upon returning to sports the injured players were moderately slower compared to the uninjured players. FH0and Pmax were also substantially lower in the injured players. At Test 2, the injured players showed a very likely increase in FH0and Pmax concomitant with improvements in early acceleration performance. Practitioners should consider assessing and training horizontal force production during sprint running after acute hamstring injuries in soccer players before they return to sports. © Georg Thieme Verlag KG Stuttgart, New York.


Plews D.J.,High Performance Sport New Zealand | Laursen P.B.,High Performance Sport New Zealand | Kilding A.E.,Auckland University of Technology | Buchheit M.,Aspire Academy for Sports Excellence
International Journal of Sports Physiology and Performance | Year: 2013

The aim of this study was to compare 2 different methodological assessments when analyzing the relationship between performance and heart-rate (HR)-derived indices (resting HR [RHR] and HR variability [HRV]) to evaluate positive adaptation to training. The relative change in estimated maximum aerobic speed (MAS) and 10-km-running performance was correlated to the relative change in RHR and the natural logarithm of the square root of the mean sum of the squared differences between R-R intervals on an isolated day (RHRday; Ln rMSSDday) or when averaged over 1 wk (RHRweek; Ln rMSSDweek) in 10 runners who responded to a 9-wk training intervention. Moderate and small correlations existed between changes in MAS and 10-km-running performance and RHRday (r = .35, 90%CI [-.35, .76] and r = -.21 [-.68, .39]), compared with large and very large correlations for RHRweek (r = -.62 [-.87, -.11] and r = .73 [.30, .91]). While a trivial correlation was observed for MAS vs Ln rMSSDday (r = -.06 [-.59, .51]), a very large correlation existed with Ln rMSSDweek (r = .72 [.28, .91]). Similarly, changes in 10-km-running performance revealed a small correlation with Ln rMSSDday (r = -.17 [-.66, .42]), vs a very large correlation for Ln rMSSDweek (r = -.76 [-.92, -.36]). In conclusion, the averaging of RHR and HRV values over a 1-wk period appears to be a superior method for evaluating positive adaption to training compared with assessing its value on a single isolated day. © 2013 Human Kinetics, Inc.


Nybo L.,Copenhagen University | Girard O.,Research and Education Center | Girard O.,Orthopaedic and Sports Medicine Hospital | Mohr M.,Copenhagen University | And 4 more authors.
Medicine and Science in Sports and Exercise | Year: 2013

Purpose: This study aimed to determine whether competitive intermittent exercise in the heat affects recovery, aggravates markers of muscle fiber damage, and delays the recovery of performance and muscle glycogen stores. Methods: Plasma creatine kinase, serum myoglobin, muscle glycogen, and performance parameters (sprint, endurance, and neuromuscular testing) were evaluated in 17 semiprofessional soccer players before, immediately after, and during 48 h of recovery from a match played in 43 C (HOT) and compared with a control match (21 C with similar turf and setup). Results: Muscle temperature was ∼1 C higher (P < 0.001) after the game in HOT compared with control and reached individual values between 39.9 C and 41.1 C. Serum myoglobin levels increased by more than threefold after the matches (P < 0.01), but values were not different in HOT compared with control, and they were similar to baseline values after 24 h of recovery. Creatine kinase was significantly elevated both immediately and 24 h after the matches, but the response after HOT was reduced compared with control. Muscle glycogen responses were similar across trials and remained depressed for more than 48 h after both matches. Sprint performance and voluntary muscle activation were impaired to a similar extent after the matches (sprint by ∼2% and voluntary activation by ∼1.5%; P < 0.05). Both of these performance parameters as well as intermittent endurance capacity (estimated by a Yo-Yo IR1 test) were fully recovered 48 h after both matches. CONCLUSION: Environmental heat stress does not aggravate the recovery response from competitive intermittent exercise associated with elevated muscle temperatures and markers of muscle damage, delayed resynthesis of muscle glycogen, and impaired postmatch performance. Copyright © 2013 by the American College of Sports Medicine.


Stanley J.,Queensland Academy of Sport | Stanley J.,University of Queensland | Peake J.M.,Queensland Academy of Sport | Peake J.M.,Queensland University of Technology | And 2 more authors.
European Journal of Applied Physiology | Year: 2014

Purpose: We investigated the acute effects of cold water immersion (CWI) or passive recovery (PAS) on physiological responses during high-intensity interval training (HIIT). Methods: In a crossover design, 14 cyclists completed 2 HIIT sessions (HIIT1 and HIIT2) separated by 30 min. Between HIIT sessions, they stood in cold water (10 C) up to their umbilicus, or at room temperature (27 C) for 5 min. The natural logarithm of square-root of mean squared differences of successive R-R intervals (ln rMSSD) was assessed pre- and post-HIIT1 and HIIT2. Stroke volume (SV), cardiac output (Q̇), O2 uptake (dot{V} V ̇ O2), total muscle hemoglobin (t Hb) and oxygenation of the vastus lateralis were recorded (using near infrared spectroscopy); heart rate, Q̇, and dot{V} V ̇ O2 on-kinetics (i.e., mean response time, MRT), muscle de-oxygenation rate, and anaerobic contribution to exercise were calculated for HIIT1 and HIIT2. Results: ln rMSSD was likely higher [between-trial difference (90 % confidence interval) [+13.2 % (3.3; 24.0)] after CWI compared with PAS. CWI also likely increased SV [+5.9 % (-0.1; 12.1)], possibly increased Q̇ [+4.4 % (-1.0; 10.3)], possibly slowed Q̇ MRT [+18.3 % (-4.1; 46.0)], very likely slowed dot{V} V ̇ O2 MRT [+16.5 % (5.8; 28.4)], and likely increased the anaerobic contribution to exercise [+9.7 % (-1.7; 22.5)]. Conclusion: CWI between HIIT slowed dot{V} V ̇ O2 on-kinetics, leading to increased anaerobic contribution during HIIT2. This detrimental effect of CWI was likely related to peripheral adjustments, because the slowing of dot{V} V ̇ O2 on-kinetics was twofold greater than that of central delivery of O2 (i.e., Q̇). CWI has detrimental effects on high-intensity aerobic exercise performance that persist for ≥45 min. © 2013 Springer-Verlag Berlin Heidelberg.


Buchheit M.,Aspire Academy for Sports Excellence | Rabbani A.,Islamic Azad University at Najafabad
International Journal of Sports Physiology and Performance | Year: 2014

The aim of the current study was to examine the relationship between performance of the Yo-Yo Intermittent Recovery Test Level 1 (Yo-YoIR1) and the 30-15 Intermittent Fitness Test (30-15IFT) and to compare the sensitivity of both tests to training. Fourteen young soccer players performed both tests before and after an 8-wk training intervention, which included 6 sessions/wk: 2 resistance training sessions, 2 high-intensity interval training sessions after technical training (4 sets of 3:30 min of generic running and small-sided games [4v4] during the first and second 4-wk periods, respectively [90-95% maximal HR], interspersed with 3 min at 60-70% maximal HR), and 2 tactical-only training sessions. There was a large correlation between 30-15IFT and Yo-YoIR1 (r = .75, 90% confidence limits [CL] 0.57;0.86). While within-test percentage changes suggested a greater sensitivity to training for the Yo-YoIR1 (+35%, 90%CL 24;45) than for the 30-15IFT (+7%; 4;10), these changes were similarly rated as almost certain (with chances for greater/similar/lower values after training of 100/0/0 for both tests) and moderate, ie, standardized difference, ES = +1.2 90%CL (0.9;1.5) for Yo-YoIR1 and ES = +1.1 (0.7;1.5) for 30-15IFT. The difference in the change between the 2 tests was clearly trivial (0/100/0, ES = -0.1, 90%CL -0.1;-0.1). Both tests might evaluate slightly different physical capacities, but their sensitivity to training is almost certainly similar. These results also highlight the importance of using standardized differences instead of percentage changes in performance to assess the actual training effect of an intervention. © 2014 Human Kinetics, Inc.


Mendez-Villanueva A.,ASPIRE Academy for Sports Excellence | Buchheit M.,ASPIRE Academy for Sports Excellence | Kuitunen S.,ASPIRE Academy for Sports Excellence | Douglas A.,ASPIRE Academy for Sports Excellence | And 2 more authors.
Journal of Sports Sciences | Year: 2011

We investigated age-related differences in the relationships among acceleration, maximum running speed, and repeatedsprint performance in 61 highly trained young male soccer players (Under 14, n=14; Under 16, n=22; Under 18, n=25). We also examined the possible influence of anthropometry (stature, body mass, fat-free mass) and biological maturation (age at peak height velocity) on performance in those three sprint-running qualities. Players were tested for 10-m sprint (acceleration), flying 20-m sprint (maximum running speed), and 10630-m sprint (repeated-sprint performance) times. Correlations between acceleration, maximum running speed, and repeated-sprint performance were positive and large to almost perfect (r=0.55-0.96), irrespective of age group. There were age-based differences both in absolute performance in the three sprint-running qualities (Under 18 > Under 16 > Under 14; P < 0.001) and when body mass and fat-free mass were statistically controlled (P < 0.05). In contrast, all between-group differences disappeared after adjustment for age at peak height velocity (P > 0.05). The large correlations among acceleration, maximum running speed, and repeated-sprint performance in all age groups, as well as the disappearance of betweengroup differences when adjusted for estimated biological maturity, suggest that these physical qualities in young highly trained soccer players might be considered as a general quality, which is likely to be related to qualitative adaptations that accompany maturation. © 2011 Taylor & Francis.


Buchheit M.,ASPIRE Academy for Sports Excellence | Simpson M.B.,ASPIRE Academy for Sports Excellence | Al Haddad H.,ASPIRE Academy for Sports Excellence | Bourdon P.C.,ASPIRE Academy for Sports Excellence | Mendez-Villanueva A.,ASPIRE Academy for Sports Excellence
European Journal of Applied Physiology | Year: 2012

The aim of the present study was to verify the validity of using exercise heart rate (HRex), HR recovery (HRR) and post-exercise HR variability (HRV) during and after a submaximal running test to predict changes in physical performance over an entire competitive season in highly trained young soccer players. Sixty-five complete data sets were analyzed comparing two consecutive testing sessions (3-4 months apart) collected on 46 players (age 15.1 ± 1.5 years). Physical performance tests included a 5-min run at 9 km h -1 followed by a seated 5-min recovery period to measure HRex, HRR and HRV, a counter movement jump, acceleration and maximal sprinting speed obtained during a 40-m sprint with 10-m splits, repeated-sprint performance and an incremental running test to estimate maximal cardiorespiratory function (end test velocity V Vam-Eval). Possible changes in physical performance were examined for the players presenting a substantial change in HR measures over two consecutive testing sessions (greater than 3, 13 and 10% for HRex, HRR and HRV, respectively). A decrease in HRex or increase in HRV was associated with likely improvements in V Vam-Eval; opposite changes led to unclear changes in V Vam-Eval. Moderate relationships were also found between individual changes in HRR and sprint [r = 0.39, 90% CL (0.07;0.64)] and repeated-sprint performance [r = -0.38 (-0.05;-0.64)]. To conclude, while monitoring HRex and HRV was effective in tracking improvements in V Vam-Eval, changes in HRR were moderately associated with changes in (repeated-)sprint performance. The present data also question the use of HRex and HRV as systematic markers of physical performance decrements in youth soccer players. © 2011 Springer-Verlag.


Mendez-Villanueva A.,ASPIRE Academy for Sports Excellence | Buchheit M.,ASPIRE Academy for Sports Excellence | Simpson B.,ASPIRE Academy for Sports Excellence | Bourdon P.C.,ASPIRE Academy for Sports Excellence
International Journal of Sports Medicine | Year: 2013

The purpose of this study was to quantify match play intensity distribution in young soccer players in relation to age, playing position and physical fitness. Distance covered and heart rate were measured (global positioning system) on 103, highly-trained young players (Under13 to Under 18) during 42 international club games. Maximal sprinting speed (MSS), estimated maximal aerobic speed (MAS) and maximal heart rate (HRmax) were assessed via field test measures. Distance covered and heart rate (HR) were categorized into 5 intensity zones relative to MSS and MAS and HRmax, respectively. Intensity distribution was significantly influenced by both age and playing position with younger groups, wide-midfielders and strikers covering the greatest distance above the MAS. There was a significant, negative, large-to-very large correlation (r=0.52-0.74) between MAS and the distance run at speeds above MAS for all positions except strikers. HR responses were not different across age groups and playing positions. Distance covered below MAS were lower in the second half for all positions (P<0.05; 0. 08<η2<0.20), while distance covered at intensities above MAS were maintained (P>0.1; 0.00<η2<0.03). This reduction in distance covered below MAS was not related to a players physical capacity. Except for strikers, a superior aerobic fitness level was unlikely to affect total distance covered but was associated with a reduced individual running demand during the game. © Georg Thieme Verlag KG Stuttgart · New York.


Buchheit M.,ASPIRE Academy for Sports Excellence | Simpson B.M.,ASPIRE Academy for Sports Excellence | Peltola E.,ASPIRE Academy for Sports Excellence | Mendez-Villanueva A.,ASPIRE Academy for Sports Excellence
International Journal of Sports Physiology and Performance | Year: 2012

The aim of the present study was to locate the fastest 10-m split time (Split best) over a 40-m sprint in relation to age and maximal sprint speed in highly trained young soccer players. Analyses were performed on 967 independent player sprints collected in 223 highly trained young football players (Under 12 to Under 18). The maximal sprint speed was defined as the average running speed during Split best. The distribution of the distance associated with Split best was affected by age (X 3 2 = 158.7, P < .001), with the older the players, the greater the proportion of 30-to-40-m Splitbest. There was, however, no between-group difference when data were adjusted for maximal sprint speed. Maximal sprint speed is the main determinant of the distance associated with Split best. Given the important disparity in Split best location within each age group, three (U12-U13) to two (U14-U18) 10-m intervals are still required to guarantee an accurate evaluation of maximal sprint speed in young players when using timing gates. © 2011 Human Kinetics, Inc.

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