The combined effects of growth and maturity status on injury risk in an elite football academy.

This study aimed to explore the interaction between growth rate on specific injury incidence and burden on pre-, circa- and post-peak height velocity (PHV) periods. Injury and stature data collected during the 2000-2020 seasons in an elite football academy were retrospectively analysed. Only players with height measurements from childhood until the attainment of adult height were included in the study (N = 84). Growth data were smoothed using a cubic spline to calculate daily growth rate and height. Growth rate was categorised into three groups: fast (> 7.2 cm/year), moderate (3.5-7.2 cm/year) and slow (< 3.5 cm/year). Percentage of observed adult height was used to classify players as pre-PHV (< 88%), circa-PHV (88-95%) or post-PHV (> 95%). Overall and specific injury incidence and burden and rate ratios for comparisons between growth rate groups were calculated on pre-, circa- and post-PHV periods, separately. Overall injury incidence and burden were greater in pre-PHV players with quicker growth rates compared to players growing moderately and slowly. All in all, players with more rapid growth-rates were at higher risk for growth-related injuries in all pre-, circa- and post-PHV periods. Post-PHV, the incidence and burden of joint/ligament injuries were 2.4 and 2.6-times greater in players growing slowly compared to players growing moderately. Practitioners should monitor growth rate and maturity status and consider their interaction to facilitate the design of targeted injury risk reduction strategies.

Peak Height Velocity Affects Injury Burden in Circa-PHV Soccer Players.

Growth and maturation are potential risk factors for soccer injuries. This research sought to describe how peak height velocity (PHV) affects overall and specific injury burden in circa- and post-PHV elite academy soccer players. Injuries and growth data collected from 2000 to 2020 were studied retrospectively. Longitudinal height records for 124 players were fitted with the Super-Imposition by Translation and Rotation model to calculate PHV (cm/year) and age at PHV. Players were classified according to PHV percentile (fast:≥75th; average: 25-75th; slow:≤25th) and maturity status (circa- or post-PHV). Overall and specific injury burden (days lost/player-season) and rate ratios for comparisons between groups were calculated based on zero-inflated negative binomial models. Confidence intervals were calculated at the 95% confidence level (CI) and the significance level was set at<0.05. In circa-PHV, players with fast PHV had 2.6 (CI: 1.4-4.8)- and 3.3 (CI:1.3-6.7)-times higher overall burden and 2.9 (CI:1.1-7.1)- and 4.1 (CI: 1.4-15.2)-times higher for growth-related injury burden compared to players with average and slow PHV, respectively. Regular monitoring of growth seems important to detect players at higher risk for being disrupted by growth-related injuries.

The effect of Brain Gym on cognitive function in older people: A systematic review and meta-analysis.

This review aimed to systematically evaluate and meta-analyze the available data on the effects of Brain Gym (BG) on cognitive function in older people. Six electronic databases were searched systematically using: "Brain Gym" AND "elderly, "Brain Gym" AND "older people". The PEDro and MINORS scales were used to evaluate methodological quality. For the meta-analysis, inverse variance or generic inverse variance was used and heterogeneity was assessed with the Chi2 test and I2 test. Ten research studies with a high to low quality. Significant changes intra- and inter-group were observed for neurocognitive outcomes in the BG groups. Findings from the metaanalysis indicated changes in the BG groups, on cognitive function by means of the Mini-Mental State Examination, were not greater than those reported in the control/comparison groups. BG will not lead to improvements in cognitive function in people with and without cognitive impairment, supported by low to high evidence.

Effect of Baduanjin on physical functioning and balance in adults with mild-to-moderate intellectual disabilities: A comparative study.

BACKGROUND: Adults with intellectual disabilities often experience mobility limitations. Baduanjin, a mindfulness-based exercise intervention, can exert positive effects on functional mobility and balance. This study examined the impact of Baduanjin on physical functioning and balance of adults with intellectual disabilities. METHOD: Twenty-nine adults with intellectual disabilities participated in the study. Eighteen received a Baduanjin intervention for 9-months; 11 participants did not receive any intervention (comparison group). Physical functioning and balance were assessed using the short physical performance battery (SPPB) and stabilometry. RESULTS: Participants in the Baduanjin group experienced significant changes in the SPPB walking test (p = .042), chair stand test (p = .015), and SPPB summary score (p = .010). No significant changes between groups were observed in any of the variables assessed at the end of the intervention. CONCLUSIONS: Baduanjin practice may cause significant, albeit small, improvements in physical functioning of adults with intellectual disabilities.

An injury burden heat map of all men's and women's teams of a professional football club over a decade.

The aim was to present a descriptive 10-season summary of injury data from all teams of a professional football club using a heat map approach. Injuries and exposure time were registered according to the FIFA consensus in all men's and women's teams from Athletic Club over 10 seasons. A team-by-injury table was created, showing the incidence, median severity, and burden in each cell. Cells were coloured based on the injury burden value using a green - yellow-red gradient (lowest to highest). The highest overall injury burden was found in the women's 2nd and 1st teams and the men's U(under)17 team (>200 days lost/1000 h). Muscle injury burden demonstrated an increasing pattern with age. Knee joint/ligament injuries, particularly anterior cruciate ligament ruptures, had the highest impact on women's teams, followed by the men's 2nd team. In comparison, ankle joint/ligament injuries had a relatively low injury burden in most teams. Growth-related injuries were the most impactful injuries in the men's U15 and younger teams, and the women's U14 team. In conclusion, epidemiological data on injuries can inform and guide injury management processes. New and improved visualization methods might be important assets when presenting injury data to key decision-makers.

Effects of physical exercise in people with epilepsy: A systematic review and meta-analysis.

BACKGROUND: Studies suggest that physical exercise lead to improvements in the psychosocial dimension, associated comorbidities as well as to a higher quality of life (QoL) in people with epilepsy. However, there is a need to provide evidence-based guidelines for its prescription. Therefore, this review aimed to systematically evaluate and meta-analyze the available data on the potential effects of physical exercise training programs in people with epilepsy. METHODS: Four electronic databases (MEDLINE/PubMed, PEDro, SPORTDiscuss and Scopus) were searched systematically from their inception until April 2022 for randomized controlled trials (RCTs), comparative studies and non-controlled studies that provided information regarding the effects of physical exercise training programs on people with epilepsy. The studies' methodological quality assessment was performed using the PEDro, the MINORS and the Quality Assessment Tool for Before-After Studies with No Control Group scales. For the meta-analysis, inverse variance or generic inverse variance was use to report mean difference or standardized mean difference for continuous data and their 95% confidence intervals (CI). Heterogeneity was assessed with the Chi-squared test and I2 test. RESULTS: After removing duplicated studies, 82 results were retrieved by the literature search and 14 were eligible for full text search. Finally, 14 studies with a methodological quality ranging from good to low quality met the inclusion criteria. Totally, 331 people with epilepsy were evaluated. Significant changes between preand post-intervention results in the exercise intervention groups were observed for QoL, fitness level, psycho-affective and neurocognitive outcomes. Findings from the meta-analysis indicated that moderate exercise led to a non-significant decrease (p = 0.08, Chi-squared test) in seizure frequency (SMD 0.33 95% CI 0.04; 0.70), while a significant effect of exercise was observed on QoL with a mean improvement of 4.72 percentage points (95% CI 0.58; 8.86, p = 0.03). CONCLUSION: Improvements on QoL, fitness level, psycho-affective and neurocognitive outcomes can be achieved through exercise training in people with epilepsy. Altogether, the findings suggest that people with epilepsy can benefit from exercising.

Relative skeletal maturity status affects injury burden in U14 elite academy football players.

Maturation progresses at different times and at different rates between individuals. Thus, differences in maturity status exist among players in the same chronological age-based category, especially in U14 players. The purpose of this prospective study was to describe injury burden according to the relative skeletal maturity status in U14 elite academy football players. From 2011 to 2020, injuries and individual exposure (training and match) were prospectively recorded in 183 male U14 players. Skeletal age (SA) was assessed using the Tanner-Whitehouse 2 method. Relative skeletal maturity status [SA minus chronological age (CA)] was classified as follows: early (SA-CA > 0.5), on-time (SA-CA ± 0.5), and late (SA-CA < -0.5). Overall and specific injury burden (days lost/1000 h) and rate ratios for comparisons between groups were calculated. Overall injury burden was 2.8 times higher (3.6 times in training) in early maturers compared with late maturers. Growth-related injuries were the most burdensome injuries in all three groups, but significant differences were not found between groups. Muscle injuries were 4 times more burdensome in early maturers compared with on-time and late maturers. Besides, joint/ligament injuries were 7 and 12 times less burdensome in late maturers than in on-time and late maturers, respectively. Significant differences between groups in overall and specific injury burden were not found in matches. Our results showed different injury patterns in U14 early, on-time, and late maturers. Hence, monitoring maturity seems crucial to detect potential injuries that cause the greatest disruption, and facilitate design of targeted injury prevention programs.

Effects of Massage and Cold Water Immersion After an Exhaustive Run on Running Economy and Biomechanics: A Randomized Controlled Trial.

ABSTRACT: Duñabeitia, I, Arrieta, H, Rodriguez-Larrad, A, Gil, J, Esain, I, Gil, SM, Irazusta, J, and Bidaurrazaga-Letona, I. Effects of massage and cold water immersion after an exhaustive run on running economy and biomechanics: A randomized controlled trial. J Strength Cond Res 36(1): 149-155, 2022-This study compares the effects of 2 common recovery interventions performed shortly after an exhausting interval running session on running economy (RE) and biomechanics. Forty-eight well-trained male runners performed an exhaustive interval running protocol and an incremental treadmill test 24 hours later at 3 speeds: 12, 14, and 16 km·h-1. Subjects randomly received either massage, cold water immersion (CWI), or passive rest (control). Runners repeated the treadmill test 48 hours after the first test. A two-way mixed analysis of variance was performed comparing groups and testing times. The massage group had significantly better recovery than the control group at 14 km·h-1 in RE (p < 0.05; η2 = 0.176) and greater stride height and angle changes at 16 km·h-1 (p < 0.05; η2 = 0.166 and p < 0.05; η2 = 0.208, respectively). No differences were observed between the CWI and control groups. The massage group had greater stride height and angle changes at 16 km·h-1 than the CWI group (p < 0.05; η2 = 0.139 and p < 0.05; η2 = 0.168, respectively). Moreover, differences in magnitude suggested moderate effects on RE (η2 = 0.076) and swing time (η2 = 0.110). These results suggest that massage intervention promotes faster recovery of RE and running biomechanics than CWI or passive rest.

Overground Robotic Program Preserves Gait in Individuals With Multiple Sclerosis and Moderate to Severe Impairments: A Randomized Controlled Trial.

OBJECTIVE: To determine how overground robotic (OR) training added to ongoing rehabilitation affects gait speed, lower extremity function, functional mobility, and fatigue in individuals with multiple sclerosis (MS) and moderate to severe gait impairments. DESIGN: Randomized controlled trial. SETTING: Outpatient setting at the Multiple Sclerosis Association of Bizkaia, an association serving MS patients in Bizkaia, Spain. PARTICIPANTS: Individuals with MS (N=36) participated in this interventional study. Inclusion criteria were age of 18 years or older, Expanded Disability Status Scale score between 4.5 and 7, and the need for assistive devices for walking outdoors. INTERVENTIONS: The control group (CG) engaged in an ongoing rehabilitation program consisting of weekly 1-hour individualized sessions. The intervention group (OR group) also participated in this program in addition to a twice-weekly individualized and progressive OR gait training intervention for 3 months, aiming to reach a maximum of 40 minutes by the end of the 3-month period. MAIN OUTCOME MEASURES: Primary outcome was the 10-meter walking test (10MWT). Secondary variables included the Short Physical Performance Battery, the timed Up and Go (TUG) test, and the Modified Fatigue Impact Scale. RESULTS: The OR group maintained 10MWT performance and significantly improved on the TUG test (P=.049, medium effect size) without increasing fatigue perception. The CG demonstrated a decline on the 10MWT (P=.044, small effect size) and reduced fatigue (P=.024, medium effect size). No time per group interaction was observed for any variable. CONCLUSION: The evaluated intervention could preserve gait speed and significantly improve functional mobility without increasing perceived fatigue in participants. Thus, OR exoskeletons could be considered a tool to deliver intensive practice of good-quality gait training in individuals with MS and moderate to severe gait impairments. Further studies are necessary to confirm these preliminary results.

Effects of 3 months of detraining on functional fitness and quality of life in older adults who regularly exercise.

BACKGROUND: Little is known about the effects of detraining in older adults, particularly those who regularly exercise. AIMS: To determine the consequences of 3 months of cessation of a habitual supervised exercise on functional fitness and quality of life in aged adults and to explore the associations among those parameters. METHODS: Thirty-eight women and 11 men (mean age 75.5 ± 5.7 years) took part in a physical exercise program for 9 months, followed by a 3-month detraining period. Participants completed physical function tests and questionnaires regarding the quality of life and leisure-time physical activity at the end of the exercise program (baseline) and 3 months later (detraining). RESULTS: After the detraining period, performance in the 8 Foot Up and Go test (p < 0.001) and the physical and mental components of the quality of life (p < 0.001) declined. Significant correlations were observed when comparing the 8 Foot Up and Go test (p < 0.05), Chair Stand test (p < 0.05), and the 6-min Walk test (p < 0.001) to the physical component of the quality of life after the detraining period. CONCLUSION: Three months of a detraining period in older people who habitually undertake supervised activities is enough to produce a decline in dynamic balance and also quality of life. To avoid the deleterious effect of periods of cessation of supervised exercise, as a suggestion, specifically designed exercises could be prescribed for an older population, with emphasis on balance exercises.

Does a 1-Year Age Gap Modify the Influence of Age, Maturation, and Anthropometric Parameters as Determinants of Performance Among Youth Elite Soccer Players?

Bidaurrazaga-Letona, I, Lekue, JA, Amado, M, and Gil, SM. Does a 1-year age gap modify the influence of age, maturation, and anthropometric parameters as determinants of performance among youth elite soccer players? J Strength Cond Res 33(9): 2541-2547, 2019-Because age-groups in soccer often comprise children born within a 2-year time frame, characteristics that define the profile of a successful player may not be appropriate for the oldest or youngest players of the same age-group. Therefore, this study aimed to determine to what extent performance was influenced by age, maturation, and body size in elite soccer players with barely 1-year age gap. Anthropometry, 15-m sprint test, modified Barrow's agility test, Yo-Yo intermittent recovery test level 1, countermovement jump, and handgrip test were conducted in players aged 12 years and under (n = 82; age, 11.1 ± 0.6 years) and between 12 and 13 years (n = 79; age, 12.8 ± 0.6 years). A total score of performance, chronological age, and age at peak height velocity were calculated. Descriptive statistics, Student's t-tests, and multiple linear regressions were performed. The explained variance in composite score was greater in the older (54%) than in the younger (30%) players. Sum of skinfolds was the primary predictor of 15-m sprint and countermovement jump in the younger group, whereas in the older group, chronological age and body size appeared as predictors of performance (41%). Body size explained the variance in most tests in older players. In the younger group, biological maturity status explained the variance in endurance (35%) and handgrip (59%) tests. In summary, chronological age and sum of skinfolds influenced the most tests; however, predictors differed between age groups. These findings highlight the importance of assessing individual differences in young male soccer players regardless of their similarity in age.

Progression in Youth Soccer: Selection and Identification in Youth Soccer Players Aged 13-15 Years.

Bidaurrazaga-Letona, I, Lekue, JA, Amado, M, and Gil, SM. Progression in youth soccer: Selection and identification in youth soccer players aged 13-15 years. J Strength Cond Res 33(9): 2548-2558, 2019-The aim of this study was to identify the factors that are important for the identification and selection of young soccer players. Ninety-four adolescent soccer players from the under-13 (U13; age = 12.3 ± 0.3 years; n = 50) and under-15 (U15; age = 14.0 ± 0.2 years; n = 44) categories belonging to a professional club participated in the study. Anthropometric measurements, physical tests (sprint, agility, endurance and jump), and maturity status (age at peak height velocity) were recorded over 4 seasons. Comparisons were performed among new players joining the club (Enter players, n = 15), players progressing to the next age category (Club players, n = 54), and players leaving the club (Deselected players, n = 25). A 2-way repeated measures analysis of variance (ANOVA) was performed to determine if significant differences existed between groups and testing time. Better physical performance and improvements observed during the season in performance were found to be one of the main factors for U13 players to continue in the club (p < 0.05-0.001). In the U15 group, although body size, maturation and physical performance appeared to be the most important characteristics for being identified to play in the club (p < 0.05), Club players demonstrated better improvements during the season (p < 0.05). Overall, these results indicate that the identification or promotion of players by coaches depends on indicators which are age-dependent. Therefore, this study has shown that the talent identification program was more a selection process than a promotion process, selecting and identifying a posteriori rather than a priori.

Health-related quality of life, handgrip strength and falls during detraining in elderly habitual exercisers.

BACKGROUND: The effects of regular exercise on physical functioning and health-related quality of life (HRQOL) have been thoroughly studied. In contrast, little is known about the changes which occur following cessation of activity (detraining). Here, we have investigated the effect of a 3 month detraining period on HRQOL and on handgrip strength in elderly people who had regularly exercised, and examined the association of these variables with falls. METHODS: Thirty-eight women and 11 men (mean age, 75.5±5.7 years) took part in a supervised physical exercise program for 9 months, followed by a 3 month detraining period. Participants completed the SF-36 HRQOL questionnaire at the beginning of detraining (baseline) and 3 months later. Handgrip strength and number of falls were also recorded. RESULTS: Participants had been exercising for 12.1±8.7 years. After the detraining period, we found a significant (p < 0.001--0.05) decline in all SF-36 dimensions, with the exception of handgrip strength. Women presented a larger decline (p < 0.05) in more items than men. During the detraining period, 18.4% participants had a fall incident. HRQOL declined in both fallers and non-fallers during detraining. Interestingly, fallers already had at baseline significantly lower values in physical functioning (p < 0.05), emotional role (p < 0.05) and mental health (p < 0.01), than non-fallers. CONCLUSIONS: An important decline was found in most items of the SF-36 following a 3 month detraining period, particularly in women. In contrast, strength of the upper limb was not affected by the detraining. The prior lower HRQOL values of those who will subsequently fall suggest that this criterion should be studied as a candidate risk factor for falls. Efforts should be made to encourage the elderly to continue with exercise activities and/or to shorten holiday break periods, in order to maintain their quality of life. TRIAL REGISTRATION: The protocol was registered as a clinical trial in the ANZCTR (trial ID: ACTRN12617000716369 ).

Pubertal development of body size and soccer-specific functional capacities in adolescent players.

Pubertal growth in body size and functional capacities were examined in adolescent soccer players (n = 33). The average age at baseline was 10.9 (9.8-11.8 years). Peak height velocity (PHV) and growth curves for body mass and functional performance (countermovement jump, 15-m sprint, agility and Yo-Yo intermittent recovery test - level 1) were determined with Bayesian multilevel models. Estimates for PHV and age at PHV were 8.1 cm/year (95% credible interval: 4.2-18.5 cm/year) and 12.9 years (95% credible interval: 11.8-15.5 years), respectively. Peak body mass velocity occurred 0.48 year after PHV. Jump performance maximum velocity occurred about 2 years after PHV and peak sprint performance maximum velocity was coincident with PHV. Agility and intermittent endurance run performance showed a quadratic trend of improvement of performance, starting to level off at about 3-4 years after PHV. The modelling procedures were efficient to determine pubertal growth curves aligned for chronological age and age at PHV, considering individual differences in maturation when interpreting the development of performance in youth soccer.

Anthropometry and Performance in Wheelchair Basketball.

This study investigated whether anthropometric characteristics, generic and specific sprinting, agility, strength, and endurance capacity could differentiate between First-Division and Third-Division wheelchair basketball (WB) players. A First-Division WB team (n = 8; age = 36.05 ± 8.25 years, sitting body height = 91.38 ± 4.24 cm, body mass = 79.80 ± 12.63 kg) and a Third-Division WB team (n = 11; age = 31.10 ± 6.37 years, sitting body height = 85.56 ± 6.48 cm, body mass = 71.18 ± 17.63 kg) participated in the study. Wheelchair sprint, agility, strength, and endurance tests were performed. The First-Division team was faster (8.7%) in 20 m without the ball, more agile (13-22%), stronger (18-33%), covered more distance (20%) in the endurance test, and presented higher values of rate of perceived exertion for the exercise load (48%) than the Third-Division team. Moreover, the individual 20-m sprint time values correlated inversely with the individual strength/power values (from r = -0.54 to -0.77, p ≤ 0.05, n = 19). Wheelchair basketball coaches should structure strength and conditioning training to improve sprint and agility and evaluate players accordingly, so that they can receive appropriate training stimuli to match the physiological demands of their competitive level.

Relationship between the relative age effect and anthropometry, maturity and performance in young soccer players.

The presence of the relative age effect (RAE) has been widely reported; however, its underlying causes have not yet been determined. With this in mind, the present study examined if anthropometry and performance were different amongst older and younger soccer players born in the same year. Eighty-eight young soccer players participated in the study (age 9.75 ± 0.30). Anthropometric measurements, physical tests (sprint, agility, endurance test, jump and hand dynamometry) and the estimation of the maturity status were carried out. Most players (65.9%) were born in the first half of the year. Older players were taller (P < 0.05), had longer legs (P < 0.01) and a larger fat-free mass (P < 0.05). Maturity offset was smaller in the older boys (P < 0.05); however, age at peak height velocity was similar. Older boys performed better in velocity and agility (P < 0.05) and particularly in the overall score of performance (P < 0.01). Stepwise regression analysis revealed that chronological age was the most important variable in the agility test and the overall score, after the skinfolds (negative effect). We report differences in anthropometry and physical performance amongst older and younger pre-pubertal soccer players. These differences may underlie the RAE.

Influence of regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and running performance.

This study investigated the influence of the regression model and initial intensity during an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and performance in elite-standard runners. Twenty-three well-trained runners completed a discontinuous incremental running test on a treadmill. Speed started at 9 km · h(-1) and increased by 1.5 km · h(-1) every 4 min until exhaustion, with a minute of recovery for blood collection. Lactate-speed data were fitted by exponential and polynomial models. The lactate threshold was determined for both models, using all the co-ordinates, excluding the first and excluding the first and second points. The exponential lactate threshold was greater than the polynomial equivalent in any co-ordinate condition (P < 0.001). For both models, the lactate threshold was lower when all co-ordinates were used than when the first and the first and second points were excluded (P < 0.001). 10-km race pace was correlated with both the exponential and polynomial lactate thresholds for all the co-ordinate conditions (r ≥ 0.75, P < 0.001 and r ≥ 0.56, P < 0.05, respectively). The results suggest that the exponential lactate threshold should be used instead of the polynomial equivalent since it is more strongly associated with performance and is independent of the initial intensity of the test.

Talent identification and selection process of outfield players and goalkeepers in a professional soccer club.

Abstract The aim of this study was to analyse the talent identification process of a professional soccer club. A preselection of players (n = 64) aged 9-10 years and a final selection (n = 21) were performed by the technical staff through the observation during training sessions and matches. Also, 34 age-matched players of an open soccer camp (CampP) acted as controls. All participants underwent anthropometric, maturity and performance measurements. Preselected outfield players (OFs) were older and leaner than CampP (P < 0.05). Besides, they performed better in velocity, agility, endurance and jump tests (P < 0.05). A discriminant analysis showed that velocity and agility were the most important parameters. Finally, selected OFs were older and displayed better agility and endurance compared to the nonselected OFs (P < 0.05). Goalkeepers (GKs) were taller and heavier and had more body fat than OFs; also, they performed worse in the physical tests (P < 0.05). Finally, selected GKs were older and taller, had a higher predicted height and advanced maturity and performed better in the handgrip (dynamometry) and jump tests (P < 0.05). Thus, the technical staff selected OFs with a particular anthropometry and best performance, particularly agility and endurance, while GKs had a different profile. Moreover, chronological age had an important role in the whole selection process.

Stride angle as a novel indicator of running economy in well-trained runners.

The main purpose of this study was to investigate the relationship between a novel biomechanical variable, the stride angle, and running economy (RE) in a homogeneous group of long-distance athletes. Twenty-five well-trained male runners completed 4-minute running stages on a treadmill at different set velocities. During the test, biomechanical variables such as stride angle, swing time, ground contact time, stride length, stride frequency, and the different sub-phases of ground contact were recorded using an optical measurement system. VO2 values at velocities below the lactate threshold were measured to calculate RE. Stride angle was negatively correlated with RE at every speed (p < 0.001, large effect sizes). Running economy was also negatively correlated with swing phase and positively correlated with ground contact time and running performance according to the best 10-km race time (p ≤ 0.05, moderate and large effect sizes). Last, stride angle was correlated with ground contact time at every speed (p < 0.001, large effect sizes). In conclusion, it seems that optimal execution of stride angle allows runners to minimize contact time during ground contact, whereby facilitating a better RE. Coaches and/or athletes may find stride angle a useful and easily obtainable measure to track and make alterations to running technique, because changes in stride angle may influence the energy cost of running and lead to improved performance.

Physical growth and changes in intermittent endurance run performance in young male Basque soccer players.

The present 4-year longitudinal study examined physical growth and development of intermittent endurance run performance in young Basque soccer players aged 10-15 years applying multilevel regression modeling. Anthropometry, predicted adult stature and Yo-Yo Intermittent Recovery level 1 test (Yo-Yo IR1) of players from the under-11 teams from the Athletic Club of Bilbao were measured at pre- and end-season (two measurements per year of study, n = 33 considered for analysis). A non-linear effect of age on intermittent endurance run was observed, with significantly higher increases in Yo-Yo IR1 between 10-11 year-old and 14-15 year-old players. The development of Yo-Yo IR1 performance in all the years of the study was influenced positively by training exposure during the seasons (P < 0.01) and independent of maturity status and body size (P > 0.05). The steady development of intermittent endurance run performance during pubertal years in adolescent Basque soccer players is partially influenced by training exposure.