Dr Anne Delextrat

Purpose: This study set out to identify the extent of the relationships between subsections of the Movement Assessment Battery for Children 2nd Edition - MABC2 (manual dexterity, aiming and catching, and balance) to PA, CRF and BMI in adolescents.

Methods: Height, BMI, the MABC2, a 20m shuttle run test and wrist-worn accelerometery PA levels (mins) were measured. Multivariable linear regression models, adjusting for sex, height and BMI were used to assess the relationship of the three subsections of the MABC2 with PA, CRF and BMI.

Results: A total of 155 adolescents, aged 13-14 years, took part in this study (77 girls, 78 boys). Balance reported significant relationships with moderate to vigorous PA (unstandardised Beta B=0.15, 95%CI 0.02-0.28), vigorous PA (B=0.06, 95%CI 0.02-0.09) and BMI (B=-0.01, 95%CI -0.02-0.005). Balance in addition to aiming and catching skills were both significantly related to adolescent CRF (B=0.30, 95%CI 0.17-0.42 and B=0.29, 95%CI 0.14-0.45, respectively).

Conclusion: This study suggests that balance is the strongest correlate skill to achieving the highest intensities of PA and healthier BMI status in adolescents.

Psychological readiness following anterior cruciate ligament reconstruction (ACLR) correlates with different return to sport outcomes. However, the relationship between strength and power and psychological readiness remains unexplored. The aim of this study was to investigate the relationship between anterior cruciate ligament return to sport after injury (ACL-RSI) scores and various hamstrings and quadriceps strength and power variables. Twelve participants (20.7 ± 2.5 years old; 174.2 ± 7.5 cm; 70.2 ± 8.5 kg; 18.2 ± 8.3% of body fat) who had an ACLR nine months or more before the study completed the ACL-RSI questionnaire and isokinetic strength testing of the hamstrings and quadriceps (60°·s−1 and 180°·s−1). Based on ACL-RSI scores, they were divided into “cases” and “controls”, deemed not psychologically ready and psychologically ready to return to previous sport performance (PILOS), respectively. The main findings are that quadriceps’ and hamstrings’ rate of torque development (RTD) and time since surgery were determinants of psychological readiness following ACLR. Furthermore, compared to controls, cases showed significantly lower quadriceps torque at angles close to full knee extension (40 deg and 30 deg from extension). They also showed lower RTD than controls, but no difference in peak torque. These results suggest that physiotherapists should facilitate athletes’ return to sport (RTS) by focusing on the restoration of RTD and strength at angles close to full knee extension.

Keywords: angle-specific torque; rate of force development; time since surgery; rehabilitation

Developmental coordination disorder (DCD) is characterized by motor learning deficits that are poorly understood within whole-body activities context.  Here we present results of one of the largest nonrandomized interventional trials combining brain imaging and motion capture techniques to examine motor skill acquisition and its underpinning mechanisms in adolescents with and without DCD. A total of 86 adolescents with low fitness levels (including 48 with DCD) were trained on a novel stepping task for a duration of 7 weeks. Motor performance during the stepping task was assessed under single and dual-task conditions. Concurrent cortical activation in the prefrontal cortex (PFC) was measured using functional near-infrared spectroscopy (fNIRS). Additionally, structural and functional magnetic resonance imaging (MRI) was conducted during a similar stepping task at the beginning of the trial.

The results indicate that adolescents with DCD performed similarly to their peers with lower levels of fitness in the novel stepping task and demonstrated the ability to learn and improve motor performance. Both groups showed significant improvements in both tasks and under single- and dual-task conditions at post-intervention and follow-up compared to baseline. While both groups initially made more errors in the Stroop task under dual-task conditions, at follow-up, a significant difference between single- and dual-task conditions was observed only in the DCD group. Notably, differences in prefrontal activation patterns between the groups emerged at different time points and task conditions. Adolescents with DCD exhibited distinct prefrontal activation responses during the learning and performance of a motor task, particularly when complexity was increased by concurrent cognitive tasks. Furthermore, a relationship was observed between MRI brain structure and function measures and initial performance in the novel stepping task. Overall, these findings suggest that strategies that address task and environmental complexities, while simultaneously enhancing brain activity through a range of tasks, offer opportunities to increase the participation of adolescents with low fitness in physical activity and sports.

In addition to a range of physiological and psychological symptoms, menopause causes a decrement to balance performance and risk of falls. This review aimed to determine the effects of exercise interventions on balance in perimenopausal and early postmenopausal women. Web of Science, PubMed, CINAHL, SPORTDiscus and Cochrane Central Register of Controlled Trials databases were searched. Randomised, controlled trials of exercise interventions in perimenopausal or early postmenopausal populations with an average age of 65 years or younger reporting balance measures were included. Risk of bias was assessed using Cochrane RoB 2. A random effects model network meta-analysis was performed to assess the effect of exercise on balance. Standardised mean differences with 95 % confidence intervals were used as the measure of effect. Twenty-six studies were included after screening. Network meta-analyses were conducted for 5 balance variables. Whole-body vibration (standardised mean difference: 2.25, confidence interval: 0.08; 4.43), balance (standardised mean difference: 1.84, confidence interval: 0.15; 3.53), balance + nutrition (standardised mean difference: 3.81, confidence interval: 1.57; 6.05) and resistance (standardised mean difference: 1.43, confidence interval: 0.41; 2.46) exercise improved Berg balance scale performance. Resistance + aerobic + balance exercise improved one-leg stance (standardised mean difference: 0.80, confidence interval: 0.39; 1.22) and whole-body vibration improved anterior-posterior (standardised mean difference: −0.89, confidence interval: −1.48; −0.31), medio-lateral (standardised mean difference: −0.58, confidence interval: −1.15; −0.01) postural sway and falls indices (standardised mean difference: −0.75, confidence interval: −1.45; −0.04). Exercise improved all balance measures and should be considered as an adjunct therapy in perimenopausal and postmenopausal women. Whole-body vibration was most frequently the highest ranked intervention; resistance and balance training also improved balance.

Background: Developmental coordination disorder affects approximately 6% of children, interfering with participation in physical activity and can persist through adulthood. However, no studies have investigated the neuromotor mechanisms of learning of a novel task with rhythmic cueing.

Methods: Movement Assessment Battery for Children-2nd edition was used to identify 48 children with probable developmental coordination disorder (13.9±0.05 yrs, 27% male) and 37 typically developed (13.9±0.10 yrs, 54% male). While instrumented with an inertial measurement unit, both groups performed a novel rhythmic stepping task and with a concurrent auditory stroop test (dual-task), underwent seven weeks of intervention with step training with rhythmic cuing and were tested for retention five weeks post-intervention.

Findings: Initially, the group with probable developmental coordination disorder had a higher variability of step timing (coefficient of variation: 0.08±0.003-typically developed – 0.09±0.004-probable developmental coordination disorder, ppppppp

Interpretation: Rhythmic cueing shows strong promise for enhancing motor learning in children with probable developmental coordination disorder.

Trial registration: Retrospectively registered on ClinicalTrials.gov with reference: NCT03150784

Keywords: Developmental Coordination Disorder, stepping, motor learning, intervention, rhythmic cueing.

BACKGROUND: This study aimed to compare the effects of in-season sprint training vs. Nordic hamstring exercise (NHE) training on risk factors for hamstring strain injuries (HSI).
METHODS: Eighteen male university football players (20.9±2.5 years; 181±7 cm; 75.8±9.1 kg; 15.2±3.5% of body fat) were randomly allocated to a sprint group or NHE group. They completed baseline isokinetic strength and sprint mechanics assessments prior to their assigned intervention performed twice weekly for 4-weeks, before post-testing. A mixed design ANOVA with repeated measures assessed time, group and interaction effects for all risk factors.
RESULTS: There were significant increases in hamstring eccentric peak torque at 60°·s-1 (+8% - 9.9%), the torque produced at 20° (+15%) and 10° (+21% - 31%), as well as a rightward shift in angle of peak torque towards knee extension (-27% - -36%) in both groups (P-1 in the strength group only and significant improvements (+29.4%) in the rate of torque development of the dominant leg at 60°·s-1 in the sprint group only (P0.05).
CONCLUSIONS: These findings suggest that both training programs can be effective to mitigate the risk of HSI, but through different mechanisms.

Objectives The objective was to determine recent cross-sectional trends in health-related fitness (HRF) in secondary school students by studying the 13–14 years old age group repeatedly over 6 years, considering parallel national trends in physical education (PE).

Methods Height, weight, broad jump, grip strength, 20 m shuttle run and throwing and catching skills were measured by the same research team using standardised techniques from 2014 to 2019. Trends in these HRF measures were assessed by linear regression, adjusting for school, sex and height. Interactions with fitness and body mass index (BMI) were tested. The number of PE lessons reported in the UK Annual School Workforce Census between 2010 and 2019 for all state-funded secondary schools was analysed.

Results Grip strength (B=−0.60, 95% CI −0.78 to –0.41), broad jump (B=−1.16, 95% CI −1.99 to –0.34), 20 m shuttle run (B=−1.85, 95% CI −2.58 to –1.12) and throwing and catching skills (B=−0.12, 95% CI −0.15 to –0.08) declined significantly over the study period. There was a greater reduction in broad jump and grip strength in adolescents with low fitness and a greater reduction in fitness and motor competence in adolescents with normal BMI. These declines coincided with a 16% reduction nationally in secondary school PE between 2010 (333 800 hours) and 2019 (280 725 hours).

Conclusion Adolescent HRF has declined in recent years, in parallel with PE lessons. Declines were observed across all young people and particularly those of low fitness and normal BMI. To reach the majority of young people, policy makers could increase PE in schools to increase activity and prevent worsening fitness and health in future generations.

Objectives. To establish pupil fitness levels, and the relationship to global norms and physical education (PE) enjoyment. To measure and describe physical activity (PA) levels during secondary school PE lessons, in the context of recommended levels, and how levels vary with activity and lesson type.

Methods. A cross-sectional design; 10 697 pupils aged 12.5 (SD 0.30) years; pupils who completed a multistage fitness test and wore accelerometers to measure PA during PE lessons. Multilevel models estimated fitness and PE activity levels, accounting for school and class-level clustering.

Results. Cardiorespiratory fitness was higher in boys than girls (ß=−0.48; 95% CI −0.56 to −0.39, p

Conclusions. PE lessons were inactive compared with current guidelines. We propose that if we are to continue to develop a range of sporting skills in schools at the same time as increasing levels of fitness and PA, there is a need to introduce additional sessions of PE activity focused on increasing physical activity.

Trial registration number NCT03286725.

Repeated sprint ability (RSA) with five changes of direction was well admitted to replicate real basketball game situations, but the additional changes of direction may affect some fundamental skills and performances in basketball. The aim of this study was to investigate the effects of RSA with one vs. five changes of direction (IRSA5COD) on squat jump (SJ), five jump test (FJT) and three point shot (3PS) performances in male basketball players. Sixteen participants (23.4 ± 2.3 years; 1.86 ± 0.10 m; 77.8 ± 7.7 kg) randomly performed eight testing sessions consisting of either RSA (10 repetitions of (15 m + 15 m)) or IRSA5COD (10 repetitions of (5 m + 5 m + 5 m + 5 m + 5 m + 5 m)) performed alone or immediately followed by the SJ, FJT or 3PS. The heart rate (HR) and ratings of perceived exertion (RPE) were continuously recorded, while blood lactate concentration was measured post-tests. Differences between RSA and IRSA5COD were evaluated by a Student t-test for paired samples, while analyses of variance (ANOVAs) with repeated measures assessed differences in SJ, FJT and 3PS performance between baseline, post-RSA and post-IRSA5COD. A significantly poorer FJT performance post-RSA was shown compared to baseline (7.47 ± 0.47 vs.7.54 ± 0.47 m, p = 0.01) and post-IRSA5COD (7.47 ± 0.47 vs. 7.56 ± 0.49%, p = 0.048). Significantly lower 3PS accuracy was also observed post-IRSA5COD compared to baseline (41.3 ± 3.1 vs.53.1 ± 2.8%, p = 0.003) and post-RSA (41.3 ± 3.1 vs. 48.1 ± 3.7%, p = 0.033). These results suggest that jump performance required for crucial actions such as lay-ups is negatively affected by longer sprints (15-m) with few changes of direction, while 3PS accuracy is impaired by shorter sprints with many changes of direction. These situations should be replicated when training these particular abilities to optimize training adaptations.

The purpose of this study was to determine how dual-task (DT) effect on gait differs among adolescents with different fitness and health profiles. The gait performances of 365 adolescents aged 13-14 years were assessed at single and DT walking. The proportional changes in gait parameters from single to dual were regressed against gender, body mass index (BMIz), three components of MABC-2 (balance, aiming &catching and manual dexterity), group (high vs low motor competence), body strength, physical fitness level using multiple regression analyses; and gender and four items of balance subtest of MABC-2 in the secondary analysis. The analyses showed that being female was associated with greater reduction in gait speed and stride length and an increase in double support time and step time; and having lower score in balance was related to greater reduction in gait speed, and cadence, and an increase in step time. Only zig-zag hopping item of the balance subtest was associated with DT effect on gait speed and stride length. No significant relationships were found between DT effect on gait and the rest of the predictors. Females and adolescents with lower level of balance function may be at higher risk of having DT deficit during walking.

Background. Pupils in secondary schools do not meet the targets for physical activity levels during physical education (PE) sessions, and there is a lack of data on the vigorous physical activity domain (VPA) in PE known to be positively associated with cardio metabolic health While PE session intensity depends on a variety of factors, the large majority of studies investigating these factors have not taken into account the nested structure of this type of data set. Therefore, the aim of this study was to investigate the relationship between various factors (gender, activity type, class location and class composition) and various activity levels during PE classes in secondary schools, using a multi-level statistical approach.

Methods. Year eight (12–13 years old) adolescents (201 boys and 106 girls) from six schools were fitted with accelerometers during one PE session each, to determine the percentage (%) of the PE session time spent in sedentary (SPA), light (LPA), moderate (MPA), vigorous (VPA) and moderate-to-vigorous (MVPA) intensity levels. Two- and three-level (pupils, n = 307; classes, n = 13, schools, n = 6) mixed-effect models were used to assess the relationship between accelerometer-measured physical activity levels (% of class time spent in various activity levels) and gender, activity type, class location and composition.

Results. Participants engaged in MVPA and VPA for 30.7 ± 1.2% and 11.5 ± 0.8% of PE classes, respectively. Overall, no significant association between gender or class composition and PA was shown. A significant relationship between activity type and PA was observed, with Artistic classes significantly less active than Fitness classes for VPA (5.4 ± 4.5 vs. 12.5 ± 7.1%, p = 0.043, d:1.19). We also found a significant association between class location and PA, with significantly less time spent in SPA (24.8 ± 4.8% vs. 30.0 ± 3.4%, p = 0.042, d:0.77) and significantly more time spent in VPA (12.4 ± 3.7% vs. 7.6 ± 2.0%, p = 0.022, d:1.93) and MVPA (32.3 ± 6.7% vs.24.8 ± 3.8%, p = 0.024, d:1.33) in outdoors vs. indoors classes.

Conclusions. The results suggest that class location and activity type could be associated with the intensity of PA in PE. It is essential to take into account the clustered nature of this type of data in similar studies if the sample size allows it.

The aim of this study was to compare the effects of vibration (Vib versus noVib) during a maximal graded cycling exercise on hormonal response, precisely on cortisol (C) and testosterone (T). Twelve active males (25 ± 5yrs; 181 ± 5cm; 80.7 ± 11.1kg) randomly performed two maximal incremental cycling tests on two separate days and at the same time of the day (09:00). The protocol consisted of incremental steps of 3 min duration performed on a PowerBIKETM that induces vibration cycling. The study was a repeated measures design and participants performed the test with and without vibration. Gas exchange and heart rate (HR) were continuously assessed and blood lactate (Bla) was recorded at the end of each incremental stage. Saliva samples were collected before and immediately after the test, and analysed for (C) and (T).

The results show that C and T increased in both cycling conditions; however, the C’s magnitude of change was significantly higher by 83% after Vib cycling in comparison to the no Vib (p = 0.014), whereas the T’s magnitude of change were not statistically different between trials (p = 0.715). Vibration induced a decrease of the T/C ratio (p = 0.046) but no significant changes were observed following noVib (p = 0.476). As a conclusion, the investigation suggests that adding mechanical vibration to cycling may potentiate a catabolic exercise-induced state, which could have potential clinical implications in rehabilitation and injury treatment. Sport experts should take this message home to carefully plan the recovery process and time during training and competitions.

Purpose: The presentation of unhealthy psychological symptoms are rising sharply in adolescents. Detrimental lifestyle behaviours are proposed as both possible causes and consequences. This study set out to compare selected measures of quality and quantity of movement between adolescents with and without unhealthy psychological symptoms.  
Methods: Using a cross sectional design, 96 participants completed the study from a whole year group of 166, age (13.36 ± 0.48) male 50.6% from a secondary school in Oxfordshire, England as a part of a larger study (EPIC) between January and April 2017. Measures were taken of quality and quantity of movement: reaction/movement time, gait pattern & physical activity, alongside psychological symptoms. Differences in movement behaviour in relation to psychological symptom and emotional problem presentation were determined using ANOVA. In the event of a significant result for the main factor of each parameter, a Bonferroni -corrected post hoc test was conducted to show the difference between categories in each group. Results for both unhealthy psychological symptoms and emotional problems were grouped into four categories (‘Close to average’, ‘slightly raised’, ‘high’ and ‘very high’). 
Results: Early adolescents with very high unhealthy psychological symptoms had 16.79% slower reaction times (p = .003, ηp2 = .170), 13.43% smaller walk ratio (p = .007, ηp2 = .152), 7.13% faster cadence (p = .005, ηp2 = .149), 6.95% less step time (p = .007, ηp2 = .153) and 1.4% less vigorous physical activity (p = .04, ηp2 = .102) than children with close to average psychological symptoms. Early adolescents with very high emotional problems had 12.25% slower reaction times (p = .05, ηp2 = .081), 10.61% smaller walk ratio (p = .02, ηp2 = .108), 6.03% faster cadence (p = .01, ηp2 = .134), 6.07% shorter step time (p = .007, ηp2 = .141) and 1.78% less vigorous physical activity (p = .009, ηp2 = .136) than children with close to average emotional problems.   
Conclusions:  Different movement quality and quantity of was present in adolescents with unhealthy psychological symptoms and emotional problems. We propose movement may be used to both monitor symptoms, and as a novel therapeutic behavioural approach. Further studies are required to confirm our findings. 

This study sought to select the most relevant test items from the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOTMP-2) and from a selection of health-related fitness tests for identifying school teenagers with poor motor coordination. The 241 participants in this study (144 boys, 97 girls aged 13–14 years old) were tested on the short form of the BOTMP-2 and on the following additional fitness tests: (a) seated medicine ball test, (b) broad jump, (c) handgrip strength, (d) alternate hand ball wall toss, (e) 10 × 5-meter agility shuttle run, and (f) Chester step test. We performed a factor analysis of participant scores on these various tasks and BOTMP-2 test items to reduce them to the least number of meaningful and useful items. Four factors explained 45% of the data variance: gross motor skills and power (including broad jump, hand ball toss, shuttle run, and sit-ups tests); fine motor skills (including copying star, following the maze and paper folding); core strength and balance (including push-ups, hopping, and balance beam); and general body strength (including medicine ball throw and handgrip). We conclude that an efficient school-based battery of test items to screen 13-14 year old adolescents for fitness and coordination should assess these four factors and might especially rely upon the broad jump, copying a star shape, hopping handgrip strength, aerobic fitness, and wall ball toss.

To investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue.

Participants

Twenty-two university male soccer players.

Design

Isokinetic strength tests were performed at 60°/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis.

Main outcome measures

The following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and 90°.

Results

There was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions.

Conclusions

Forty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period.

To assess the feasibility of Zumba Gold® in people with PD, and to investigate the effects of dance styles and number of sessions on activity levels and physiological load.

Design

Repeated measure uncontrolled (single group) feasibility study.

Setting

Eleven participants (age: 64.0 ± 8.1 years) with mild-to-moderate idiopathic PD (Hoehn & Yahr stage < 3.0) took part in a screening session, followed by six Zumba Gold® workouts each separated by one week, and a follow-up interview six months later.

Main outcome measures

The main feasibility parameters measured were retention, compliance, and adverse events. Furthermore, during each Zumba Gold® session, physical activity levels were measured using tri-axial accelerometers, while physiological load was assessed by average heart rate (HRmean). A two-way ANOVA with repeated measures assessed the effects of dance styles and session number on activity level and HR.

Results

73% retention and 81% compliance were achieved, and no adverse events were recorded. Participants’ enjoyment was high and 38% started Zumba Gold® classes in the community after intervention. HR values were similar between dance styles and within the American College of Sports Medicine (ACSM)’s recommendations in 50% of participants. Backwards steps reduced physiological load but improvements in activity levels between the first and last sessions show that steps could be learnt with time.

Conclusions

Zumba Gold® is safe and enjoyable for people with PD. The excellent compliance and positive participants’ feedback suggest the need for a larger-scale trial.

Purpose: The aim was to identify benefits of compression garments used for recovery of exercised-induced muscle damage. Methods: Computer-based literature research was performed in September 2015 using four online databases: Medline (PubMed), Cochrane, WOS (Web Of Science) and Scopus. The analysis of risk of bias was completed in accordance with the Cochrane Collaboration Guidelines. Mean differences and 95% confidence intervals were calculated with Hedges' g for continuous outcomes. A random effect meta-analysis model was used. Systematic differences (heterogeneity) were assessed with I statistic. Results: Most results obtained had high heterogeneity, thus their interpretation should be careful. Our findings showed that creatine kinase (standard mean difference = - 0.02, 9 studies) was unaffected when using compression garments for recovery purposes. In contrast, blood lactate concentration was increased (standard mean difference = 0.98, 5 studies). Applying compression reduced lactate dehydrogenase (standard mean difference = - 0.52, 2 studies), muscle swelling (standard mean difference = - 0.73, 5 studies) and perceptual measurements (standard mean difference = - 0.43, 15 studies). Analyses of power (standard mean difference = 1.63, 5 studies) and strength (standard mean difference = 1.18, 8 studies) indicate faster recovery of muscle function after exercise. Conclusions: These results suggest that the application of compression clothing may aid in the recovery of exercise induced muscle damage, although the findings need corroboration.

The objectives were to compare the metabolic load elicited by Zumba classes and DVD workouts and link the physiological responses to participants’ psychological characteristics. Fifteen women (25.4 ± 4.3 years old; 164.9 ± 5.1 cm; 56.9 ± 5.8 kg; 23.9 ± 4.9% body fat) performed three Zumba classes and three Zumba DVD workouts using a repeated measure design. Energy expenditure was assessed by extrapolating oxygen cost from heart rate (HR) using regressions from a preliminary incremental running test. Differences between Zumba classes and Zumba DVD workouts were assessed by Student’s T tests and repeated measures analysis of variance and correlations between physiological and psychological variables by the Pearson’s coefficient. Results showed that Zumba classes allowed greater energy expenditure compared to Zumba DVD workouts (6.8 ± 0.9 vs 5.6 ± 0.9 kcal · min, 95% confidence interval (CI) limits: 0.3–2.1, P = 0.016), with significant differences in the time spent with a HR above 85% of HR reserve (14.7 vs 1.7%, 95% CI: 5.6–20.4, P = 0.021). Furthermore, women with a greater autonomy score showed a smaller difference between DVD and class (r = 0.511, P = 0.048), while greater differences were shown in women with greater interpersonal skills (r = −0.563, P = 0.028). The results suggest that while both types of workouts are suitable to maintain fitness Zumba classes allow greater energy expenditure.

Purpose: To investigate the reliability and determinants of performance in a new test of planned agility in elite junior basketball players. Methods: Seventeen female (15.1 ± 0.4 y, 176.9 ± 11.2 cm, 65.7 ± 10.9 kg) and 42 male (14.9 ± 0.4 y, 193.7 ± 8.1 cm, 79.0 ± 12.0 kg) elite junior basketball players performed 5 fitness tests presented in a random order, including a 20-m sprint, a planned-agility test, a triple bilateral horizontal countermovement jump, and 2 triple unilateral horizontal countermovement jumps (with each leg separately). The novelty of the planned-agility test is that it included both offensive and defensive movements. The determinants of planned agility were assessed by a stepwise-regression analysis, and the reliability of the new test was evaluated by the intraclass correlation coefficient and the typical error of measurement. Results: The main results show good reliability of the new test of planned agility. In addition, the determinants of planned-agility performance were different between genders, with sprint performance explaining 74.8% of the variance for girls, while unilateral jump performance and body mass were the most important for boys, accounting for 24.0% and 8.9% of the variance, respectively, in planned agility. Conclusions: These results highlight a gender effect on the determinants of planned-agility performance in young elite basketball players and suggest that straight-line sprint and unilateral horizontal tests must be implemented to test elite junior players.

Purpose: To evaluate the effect of simulated soccer on the hamstrings eccentric torque-angle profile and angle of peak torque (APTeccH), and on the hamstrings:quadriceps torque ratio at specific joint angles (ASHecc:Qcon). Methods: The authors assessed dominant-limb isokinetic concentric and eccentric knee flexion and concentric knee extension at 120°/s in 9 semiprofessional male soccer players immediately before and after they completed the Loughborough Intermittent Shuttle Test (LIST). Results: The LIST resulted in significant decreases in eccentric hamstrings torque at 60°, 50°, and 10° and a significant (21.8%) decrease in ASHecc:Qcon at 10° (P < .05). APTeccH increased from 7.1° ± 1.0° to 18.8° ± 4.2° (P < .05). Eccentric hamstrings peak torque significantly declined from 185.1 ± 70.4 N·m pre-LIST to 150.9 ± 58.5 N·m post-LIST (P = .002), but there were no significant changes in hamstrings or quadriceps concentric peak torque (P = .312, .169, respectively). Conclusions: Simulated soccer results in a selective loss of eccentric hamstrings torque and hamstrings-to-quadriceps muscle balance at an extended joint position and a shift in the eccentric hamstrings APT to a shorter length, changes that could increase vulnerability to hamstrings injury. These findings suggest that injury-risk screening could be improved by evaluating the eccentric hamstrings torque-angle profile and hamstrings strength-endurance and that the development of hamstrings fatigue resistance and long-length eccentric strength may reduce injury incidence.

The aim of this study was to investigate the effects of a weight loss intervention based on physical exercise on the relationship between energy cost and stride frequency during walking in obese teenagers. Participants aged 13–16 years old were assigned to a training (n = 14) and control (n = 10) groups. During eight weeks, the training group performed three 60-min weekly sessions of high-intensity intermittent activities coupled with aerobic training. Body composition, gait parameters and energy cost during 4-min walking bouts at participants’ most comfortable speed and preferred stride frequency (PSF), PSF-10%, PSF + 10%, PSF-20% and PSF + 20% were measured before and after intervention. The effects of training and stride frequencies on the energy cost of walking were analysed by an ANOVA with repeated measures. The main results showed that the exercise intervention induced a significant increase in walking speed (+23.2%), and significant decreases in body mass (−1.4%), body fat percentage (−2.1%) and energy cost of walking at various frequencies (decreases ranging from −10.5% to −20.4%, p < .05). In addition, significantly greater decreases were shown at high frequencies (p < .05). No significant differences were shown in the control group (p > .05). These results suggest that this type of training is beneficial to reduce walking energy cost of obese teenagers, in particular at high frequencies. This should improve their well-being during daily activities.

There is no current study that examined sport-specific tests of reactive-agility and change-of-direction-speed (CODS) to repli-cate real-sport environment in handball (team-handball). This investigation evaluated the reliability and validity of two novel tests designed to assess reactive-agility and CODS of handball players. Participants were female (25.14 ± 3.71 years of age; 1.77 ± 0.09 m and 74.1 ± 6.1 kg) and male handball players (26.9 ± 4.1 years of age; 1.90 ± 0.09 m and 93.90±4.6 kg). Variables included body height, body mass, body mass index, broad jump, 5-m sprint, CODS and reactive-agility tests. Results showed satisfactory reliability for reactive-agility-test and CODS-test (ICC of 0.85-0.93, and CV of 2.4-4.8%). The reac-tive-agility and CODS shared less than 20% of the common variance. The calculated index of perceptual and reactive capaci-ty (P&RC; ratio between reactive-agility- and CODS-performance) is found to be valid measure in defining true-game reactive-agility performance in handball in both genders. There-fore, the handball athletes’ P&RC should be used in the evalua-tion of real-game reactive-agility performance. Future studies should explore other sport-specific reactive-agility tests and factors associated to such performance in sports involving agile maneuvers.

The purpose of this study was to determine the substrate oxidation rate and the exercise intensity at which maximal lipid oxidation and ventilatory threshold (VT) occur in obese (BMI: 36.6 ± 6.3 kg · m−2) and normal-weight adolescent girls (BMI: 18.7 ± 1.6 kg · m−2) aged 14–18 years. Substrate oxidation rate was determined by gas exchange using an incremental field test involving walking. Body composition was assessed by bioelectrical impedance. Carbohydrate oxidation rates were significantly higher in obese than in normal-weight girls at speeds ranging from 4 to 6 km · h−1 (P < 0.05), whereas no significant differences were observed between groups regarding lipid oxidation rates. The crossover point of substrate utilisation and the VT were significantly lower in obese than in normal-weight adolescents (P < 0.05). Maximal lipid oxidation rate was observed at 46 ± 15 and 53 ± 15 %E (Formula presented.) O2max in obese and normal-weight adolescents, respectively. At these intensities, the Lipoxmax was significantly lower in obese than in normal-weight girls (6.7 ± 2.3 versus 8.9 ± 3.5 mg · min−1 · kg−1 FFM, P < 0.05, 95% CI: −3.7 to −0.7, d = −0.74). The present results have implications in designing interventions to promote lipid oxidation and energy expenditure during walking in severely obese adolescent girls.

The physiological load experienced during basketball drills is crucial to understand players' adaptation to team-sport training and plan physical-conditioning programs. Purpose: To compare mean heart-rate (HRmean) responses by playing position during 2-a-side (2v2) and 3-a-side (3v3) ball drills in male junior basketball players and explore the relationship between HRmean and repeated-sprint ability (RSA). Methods: Thirty- one players volunteered to participate in this study. On separate occasions, they performed 2v2 and 3v3 ball drills and 6 repetitions of shuttle-run sprints of 20 m (10+10 m), departing every 20 s (RSA). Ball drills took place on the full length but only half the width of the court and were three 4-min bouts separated by 1-min rest periods. An analysis of variance (ANOVA) assessed the effect of the number of players on court (2v2 vs 3v3) and playing position (guards vs forwards vs centers) on HRmean, and a Pearson correlation coefficient evaluated the relation between HRmean and RSA. Results: The main results showed greater HRmean in 2v2 than in 3v3 ball drills (P< .001) in all playing positions (90.7% ± 1.3% vs 87.6% ± 3% of HRpeak in guards, 91.3% ± 2.1% vs 87.5% ± 3.7% of HRpeak for forwards, and 88.2% ± 3.5% vs 82.2% ± 5.6% of HRpeak in centers, respectively, for 2v2 and 3v3). In addition, centers were characterized by lower HRmean than guards and forwards in 3v3 only (P - .018). Conclusions: These results suggest that 2v2 drills should be preferred to 3v3 drills for aerobic conditioning, in particular for centers. Finally, RSA does not seem to influence players' acute responses to ball drills.

AIM:

The aim of the study was to investigate the effects of playing an official national-level basketball match on repeated sprint ability (RSA) and stride kinematics.

METHODS:

Nine male starting basketball players (22.8±2.2 years old, 191.3±5.8 cm, 88±10.3 kg, 12.3±4.6% body fat) volunteered to take part. Six repetitions of maximal 4-s sprints were performed on a non-motorised treadmill, separated by 21-s of passive recovery, before and immediately after playing an official match. Fluid loss, playing time, and the frequencies of the main match activities were recorded. The peak, mean, and performance decrement for average and maximal speed, acceleration, power, vertical and horizontal forces, and stride parameters were calculated over the six sprints. Differences between pre- and post-match were assessed by student t-tests.

RESULTS:

Significant differences between pre- and post-tests were observed in mean speed (-3.3%), peak and mean horizontal forces (-4.3% and -17.4%), peak and mean vertical forces (-3.4% and -3.7%), contact time (+7.3%), stride duration (+4.6%) and stride frequency (-4.0%), (P<0.05). In addition, the variation in several RSA parameters, such as peak and mean speed, peak and mean acceleration, mean power, and peak and mean vertical force were significantly correlated to fluid loss and sprint, jump and shuffle frequencies (P<0.05).

CONCLUSION:

These results highlight that the impairment in repeated sprint ability depends on the specific activities performed, and that replacing fluid loss through sweating during a match is crucial.