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This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

Resumen Para preservar la salud de los jovenes de entre 5-17 anos, la Organizacion Mundial de la Salud recomienda niveles de actividad fisica de al menos 60 minutos al dia de actividad fisica moderada o sostenida. Por tomar el caso de Francia, los jovenes son el grupo de edad mas activo y, en general, estan sanos, pero su nivel de actividad fisica y/o deportiva es insuficiente y disminuye de generacion en generacion. La educacion fisica y deportiva y las practicas deportivas de ocio no son suficientes para compensar el descenso de la actividad fisica en la vida cotidiana. Los analisis demuestran que la inactividad contribuye en gran medida al sobrepeso y la obesidad, factores nocivos para la salud. Ademas, se reconoce que el nivel de actividad fisica en la infancia/adolescencia condiciona el nivel de actividad en la edad adulta. Las ninas y los ninos tienen las mismas capacidades fisicas antes de la pubertad. Su potencial de resistencia aerobica es muy alto, por lo que no es necesario restringirlos por miedo al cansancio o al agotamiento durante esfuerzos de menos de 10-15 minutos. En cambio, su potencial de fuerza es moderado y su potencial de resistencia es bajo. El nino esta «preparado» para el deporte de competicion cuando busca comparar sus propias habilidades con las de sus companeros. En el caso de los deportes de equipo, el nino tambien debe comprender el proceso competitivo subyacente: la estrategia y la cooperacion dentro del grupo. Esto no suele ocurrir hasta la edad de 10-12 anos. Las lesiones por uso excesivo, el sindrome de sobreentrenamiento e incluso el sindrome de agotamiento son posibles en los atletas jovenes. Como las secuelas de estos trastornos pueden tener un impacto significativo en el crecimiento oseo y en el desarrollo psicologico del joven, es importante estar alerta y reaccionar tan pronto como aparezcan los signos prodromicos.

Background The aim of this study was to review, systematically, evidence concerning the link between the ACTN3 R577X polymorphism and the rates and severity of non-contact injuries and exercise-induced muscle damage in athletes and individuals enrolled in exercise training programs. Methods A computerized literature search was performed in the electronic databases PubMed, Web of Science, and SPORTDiscus, from inception until November 2020. All included studies compared the epidemiological characteristics of non-contact injury between the different genotypes of the ACTN3 R577X polymorphism. Results Our search identified 492 records. After the screening of titles, abstracts, and full texts, 13 studies examining the association between the ACTN3 genotypes and the rate and severity of non-contact injury were included in the analysis. These studies were performed in 6 different countries (Spain, Japan, Brazil, China, Republic of Korea, and Italy) and involved a total participant pool of 1093 participants. Of the studies, 2 studies involved only women, 5 studies involved only men, and 6 studies involved both men and women. All the studies included were classified as high-quality studies (≥6 points in the Physiotherapy Evidence Database (PEDro) scale score). Overall, evidence suggests there is an association between the ACTN3 R577X genotype and non-contact injury in 12 investigations. Six studies observed a significant association between ACTN3 R577X polymorphism and exercise induced muscle damage: two with non-contact ankle injury, three with non-contact muscle injury, and one with overall non-contact injury. Conclusion The present findings support the premise that possessing the ACTN3 XX genotype may predispose athletes to a higher probability of some non-contact injuries, such as muscle injury, ankle sprains, and higher levels of exercise-induced muscle damage.

BACKGROUND Lacrosse is one of the fastest-growing sports in the United States. Its rules regarding permitted contact differ by sex and age. There are no known studies using a nationally representative data set to analyze lacrosse injury patterns over several years by sex and age in the youth population. METHODS A retrospective analysis was performed using data from the National Electronic Injury Surveillance System for youth aged 11-18 years who were treated for lacrosse-related injuries in U.S. emergency departments from 2000 to 2016. Based on our review of the case narratives, we created and coded a new injury-mechanism variable. We generated national estimates from 6406 cases. RESULTS An estimated 206,274 lacrosse-related injuries to youths aged 11-18 years were treated in U.S. emergency departments from 2000 to 2016. The rate of injuries per 10,000 significantly increased from 1.9 in 2000 to a peak of 5.3 in 2012 (p < 0.0001), followed by a significant decrease to 3.4 in 2016 (p = 0.020). Injury mechanism, body part injured, and diagnosis differed by sex. Boys were 1.62 times (95%CI: 1.25-2.09) more likely than girls to be injured by player-to-player contact. Girls were 2.21 times (95%CI: 1.96-2.49) more likely than boys to have non-contact injuries. Overall, as age increased, the percentage of injuries from lacrosse sticks decreased and player-to-player contact increased. CONCLUSION Despite additional protective regulations in the sport, lacrosse is an important source of injury where we continue to see differences by sex and age. This study supports the continuation, modification, and addition of rules aimed at reducing lacrosse injury risk.

Resume Contexte La dysplasie osteofibreuse (OFD) est une lesion fibro-osseuse intracorticale benigne qui touche les plus souvent la diaphyse du tibia et de la fibula de l’enfant, et dont le meilleur traitement n’a pas encore ete determine. Nous avons realise une etude retrospective chez les enfants de moins de 10 ans avec OFD du tibia ou de la fibula pour determiner si la chirurgie precoce est indiquee, et quelle est la meilleure option chirurgicale. Hypothese Les lesions symptomatiques doivent etre traitees de facon proactive, et un traitement approprie assure des bons resultats. Methodes Nous avons analyse retrospectivement 21 enfants avec OFD du tibia (n = 22) et de la fibula (n = 1). Le traitement a ete adapte en fonction de la gravite des symptomes (deformation, douleur ou fracture pathologique) et de la taille de la lesion. Les patients ont ete divises en quatre groupes (Gr.): Gr. 1 : observation (n = 4) ; Gr. 2 : curettage et allograft (n = 6) ; Gr. 3 : curettage, allograft et enclouage centromedullaire elastique stable (ESIN) (n = 9) ; Gr. 4 : resection extraperiostee et transfert osseux (n = 5) ; un patient a ete traite avec deux techniques (24 procedures au total). Tous les patients ont beneficie d’un suivi radioclinique regulier afin d’evaluer la consolidation osseuse et le taux de complications. Resultats Les quatre patients asymptomatiques du Gr. 1, avec OFD confirmee a la biopsie, ont ete observes. Le Gr. 4 avait le taux le plus bas de recidive locale : 0 cas (0 %) vs 4 (66,7 % ; Gr. 2) vs 1 (11,1 % ; Gr. 3) (p = 0,002), de deformation : 0 cas (0 %) vs 0 (0 % ; Gr. 2) vs 3 (50 % ; Gr. 3) (p = 0,023), et de fracture pathologique : 0 cas (0 %) vs 0 (0 % ; Gr. 2) vs 1 (16,7 % ; Gr. 3) (p = 0,006) ; neanmoins, le temps de consolidation : 6,8 vs 2 (Gr. 2) vs 2,7 mois (Gr. 3) (p = 0,017) et le taux de complications etaient plus eleves que dans le Gr. 2 et le Gr. 3 (p Discussion La biopsie osseuse est fondamentale dans la prise en charge des patients avec ODF et permet d’eliminer le diagnostic d’adamantinoma ou d’infection. L’observation est reservee aux patients asymptomatiques tandis que la chirurgie est indiquee chez les patients avec douleur, fracture pathologique ou deformation osseuse. Chez les patients symptomatiques avec une lesion de taille moderee, l’ESIN permet de preserver l’axe anatomique de l’os ; par contre, les lesions circonferentielles, ou les recidives, peuvent beneficier d’une resection extraperiostee et d’un transfert osseux, meme si le taux de complications est relativement eleve. Niveau de preuve III ; etude cas controle.

Souissi, MA, Elghoul, Y, Souissi, H, Masmoudi, L, Ammar, A, Hamdi chtourou, and Souissi, N. The effects of three corrections strategies of errors on the snatch technique in 10-12-year-old children: A randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2020-Sports movement correction is one of the major problems for motor control and learning. Therefore, the purpose of the present study was to determine which of the 3 strategies, i.e., the self-observation method with direct instructions (SO-DI), self-observation alone (SO), or the direct instruction (DI), would be useful for correcting errors during the snatch technique. Forty-eight children with 2 months of experience were randomly assigned to one of 4 training conditions: SO-DI, SO, DI, or control. In this study, the experience lasted 15 sessions. Subjects completed the test sessions before (T0) and after (T1) 12 training sessions and a retention test session after 2 weeks (T2). The Kinovea version 0.8.15 software was used to measure the kinematic parameters of weightlifting performance. After the training intervention, the data showed that the SO-DI group registered a greater improvement in all kinematic parameters compared with the SO, DI, and control groups, and this benefit was present 2 weeks later in the retention test (e.g., the horizontal displacement of the bar in the first pull with respect to the starting position [T1 vs. T0: +32.57 ± 6.69%, d = 1.87, p < 0.001; T2 vs. T0: 25.07 ± 11.55%, d = 1.32, p < 0.001] and the horizontal displacement of the bar between the receiving position and the reference line [T1 vs. T0: 24.34 ± 29%, d = 1.17, p < 0.01; T2 vs. T0: 25.53 ± 30.4%, d = 0.99, p < 0.01]). The results of the present study could have practical implications for physical education teachers because, even if practice is required to improve the technique, the effectiveness of the learning process is essential to enhance learner self-efficacy and motivation.

Rey, E, Costa, PB, Corredoira, FJ, and Sal de Rellan Guerra, A. Effects of age on physical match performance in professional soccer players. J Strength Cond Res XX(X): 000-000, 2019-This study aimed to evaluate the effects of age using a large-scale analysis of match physical performance in professional soccer players. A total of 10,739 individual match observations were undertaken on outfield players competing in the first and second divisions of the Spanish soccer professional leagues during the 2017-2018 season, using a computerized tracking system (TRACAB, Chyronhego, New York, USA). The players were classified into five positions and into 5 age groups (

Szivak, TK, Thomas, MM, Pietrzak, RH, Nguyen, DR, Ryan, DM, and Mazure, CM. Obesity Risk Among West Point Graduates Later in Life. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this investigation was to evaluate sex differences in health and fitness outcomes among United States Military Academy (USMA) graduates (class years 1980-2011). Subjects (n = 701 men, 641 women, age: 45.7 ± 9.3 years) were surveyed as a part of a larger investigation on risk and resiliency factors among USMA graduates. Physical activity was assessed using the International Physical Activity Questionnaire (IPAQ) short form and calculation of weekly metabolic equivalents (METs). Overweight and obesity status were assessed by body mass index (BMI). Significance for the study was set at p ≤ 0.05. Obesity rates for men (30.1%) were significantly higher than for women (16.6%). Men reported significantly higher (p = 0.01) vigorous METs·wk (1,214.6 ± 1,171.6) than women (1,046.8 ± 1,133.2) despite significantly higher (p = 0.00) BMI values (28.75 ± 4.53 kg·m) than women (25.90 ± 5.48 kg·m). Women were 89% more likely to have ever been on a diet and reported higher (15.2%) Army Body Composition Program enrollment rates than men (6.3%). Obesity rates among men reflect trends seen in the broader military, Veteran, and U.S. adult populations, whereas obesity rates among women were lower. Men may be at a greater risk for obesity later in life despite higher self-reported physical activity; however, lean body mass and self-report bias should be considered. Because lifetime obesity may be influenced by factors other than physical activity, health initiatives should use a comprehensive approach early in the career of military officers.

BACKROUND AND OBJECTIVE: Lower limb strength after stroke, particularly of the more paretic side, is known to correlate with comfortable gait speed. This meta-analysis sought to determine the relative value of 6 muscle group strengths as explanators of comfortable gait speed. METHODS: Relevant literature was sought using PubMed, CINAHL Scopus, and a hand search. Information on samples, measurements, and correlations were extracted. Correlational data were subjected to meta-analysis. RESULTS: Results from 6 studies were consolidated. The summary correlations between paretic lower limb strength and comfortable gait speed ranged from 0.45 to 0.61. Data were highly heterogeneous but did not show publication bias. CONCLUSIONS: The correlation between the lower limb strength and comfortable gait speed strength was moderate. However, it does not provide an adequate explanation to guide clinical practice.

Background Emerging epidemiological evidence suggests that compared to engaging in 1 activity mode alone, a combination of moderate-to-vigorous physical activity (MVPA: brisk walking/jogging, cycling) and muscle-strengthening exercise (MSE: push-ups/sit-ups, using weight machines) has more favorable associations with optimal weight status. However, few studies have examined the dose-dependent and joint associations of MVPA and MSE with obesity. Methods Based on cross-sectional analyses of the European Health Interview Survey Wave 2 (2013–2014), we examined prevalence ratios (PRs) of joint and stratified associations between MVPA (4 categories: (i) 0 min/week, (ii) 1–149 min/week, (iii) 150–299 min/week, and (iv) ≥300 min/week) and MSE (3 categories: (i) 0 day/week, (ii) 1 day/week, and (iii) ≥2 days/week) with body mass index-defined obesity (body mass index of ≥30.0 kg/m2) using Poisson regression with robust error variance. PRs were examined unadjusted and adjusted for sociodemographic and lifestyle characteristics (e.g., sex, age, education, income, and smoking status). Results Data were available for 280,456 adults (≥18 years), of which 46,166 (15.5%) were obese. The interaction MVPA × MSE guideline adherence was statistically significant for obesity (p ≤ 0.05). The joint MVPA–MSE analysis showed that compared to the reference group (i.e., no MVPA and no MSE), the PRs followed a dose-dependent pattern, with the lowest observed among those reporting ≥150 MVPA min/week and ≥1 MSE days/week (PR: 0.43; 95% confidence interval: 0.41–0.46). When stratified across each MVPA strata, the PRs were mostly lower among those engaging in MSE 1 day/week, as compared to those doing MSE ≥2 days/week. Conclusion There was evidence for a dose-dependent association between joint MVPA–MSE with a reduced prevalence of obesity. Public health strategies for the prevention and management of obesity should recommend both MVPA and MSE.

The aim of the study was to investigate whether jerk cost (JC) can discriminate between swimming levels. Nine elite and nine non-elite swimmers swam a 50-m front-crawl sprint wearing a 3D accelerometer on their back between the inferior angles of the scapulae. Lap times and JC were calculated from the acceleration signal and compared between groups and between swimmers within a group. The elite swimmers swam significantly faster lap times than the non-elite swimmers (p < 0.001). They did so with significantly lower levels of JC compared to the non-elite swimmers (p = 0.005). Furthermore, a stepwise multiple linear regression showed JC accounted for 32.9% of the variation in lap time of the elite swimmers. These results indicate that it is possible to discriminate elite from non-elite swimmers using JC: elite swimmers swim with lower JCs than non-elite swimmers. Additionally, swimming at higher speed is associated with more accelerations and decelerations in both elite and non-elite swimmers, which is reflected by higher JCs and lower smoothness. In sum, JC provides an index of swimming technique that is easy to use in training practice.

Sexual and gender minority youth frequently experience bullying, which often contributes to higher depressive symptoms and lower self-esteem. Given that physical activity (PA) can mitigate depressive symptoms and improve self-esteem, we examined the moderating effect of PA on the relationship between bullying and mental health among sexual and gender minority youth.Data from the Lesbian, Gay, Bisexual, Transgender, and Queer National Teen Survey (n = 9890) were analyzed. Hierarchical regression analyses examined the influence of history and frequency of being bullied, PA, and the interaction of these variables on depressive symptoms and self-esteem. Simple slopes analyses were used to probe significant interactions.Results indicated the importance of accounting for bullying history when examining effects of PA on mental health. PA was negatively related to depression (t = -4.18, p0.001) and positively related to self-esteem (t = -12.11, p0.001). Bullying frequency was positively related to depression (t = 19.35, p0.001) and negatively related to self-esteem (t = -12.46, p0.001). There was a significant interaction between bullying frequency and PA for depression (t = 4.45, p0.001) and self-esteem (t = -4.69, p0.001). Post hoc analyses suggested that the positive effects of PA on mental health may be limited to those not bullied because it had a negligible effect on those who were bullied.Results suggest that sexual and gender minority youth exercise interventions aiming to improve mental health should first address bullying history; otherwise, their effectiveness may be limited to those who have been bullied.

Melanocortin-4 receptor (MC4R), the most important monogenetic cause of human metabolic disorders, has been of great interest to many researchers in the field of energy homeostasis and public health. Because MC4R is a vital pharmaceutical target for maintaining controllable appetite and body weight for professional athletes, previous studies have mainly focused on the central, rather than the peripheral, roles of MC4R. Thus, the local expression of MC4R and its behavioral regulation remain unclear. In an attempt to shed light on different directions for future studies of MC4R signaling, we review in this article a series of recent and important studies exploring the peripheral functions of MC4R and the direct physiological interaction between peripheral organs and central MC4R neurons.

Triceps tendon rupture is rare and easily missed on presentation. A 58-year-old man was seen in our accident and emergency department with an inability to extend his right elbow against gravity after he fell. Ultrasound and MRI confirmed the suspected diagnosis of a traumatic triceps tendon rupture and excluded additional injuries. Surgical repair was carried out by a bone anchor suture reinsertion of the tendon to the olecranon. After 2 weeks of cast immobilisation, an early active range of motion (ROM) rehabilitation schedule was followed, resulting in excellent elbow function at 12 weeks postoperatively.In conclusion, it is important to suspect this rare injury and use additional studies to confirm the diagnosis of triceps tendon rupture. Also, good clinical outcome with regards to function can be achieved using bone anchor suture repair and an early active ROM rehabilitation schedule.

A 12-year-old skeletally immature male athlete presented for evaluation with acute bilateral knee pain. Initial radiographs revealed subtle lucency of the medial proximal tibial physis and MRI was recommended. On MRI, broad-based intravasation of the physis into the proximal femoral and tibial physes was observed. This represented physeal widening, a phenomenon that has been observed in skeletally immature athletes presenting for acute knee pain. While such changes to the physis may be quite prominent on MRI, conventional radiographic findings may be much more subtle. As many causes of chronic knee pain in this population are managed with active rehabilitation, a high index of suspicion for this diagnosis in the presence of physeal abnormalities may warrant evaluation with MRI. The literature suggests this pathology will resolve with rest, but, if weight-bearing activities are continued, there is a risk for significant growth abnormalities.

Background Esports players, like traditional athletes, practice for long hours and, thus, are vulnerable to the negative health effects of prolonged sitting. There is a lack of research on the physical activity and the health ramifications of prolonged sitting by competitive players. The purpose of this study was to investigate activity levels, body mass index (BMI), and body composition in collegiate esports players as compared to age-matched controls. Methods Twenty-four male collegiate esports players and non-esports players between 18 and 25 years of age signed a written consent to participate. Physical activity was examined using daily activity (step count) with a wrist-worn activity tracker. A questionnaire assessing physical activity was also administered. Secondary outcomes included body-fat percentage, lean-body mass, BMI, and bone mineral content measured using dual X-ray absorptiometry. Results The step count in the esports players was significantly lower than the age-matched controls (p = 0.004; 6040.2 ± 3028.6 vs. 12843.8 ± 5661.1). Esports players exhibited greater body-fat percentage (p = 0.05), less lean body mass (p = 0.003), and less bone mineral content (p = 0.03), despite no difference in BMI between the esports and non-esports players. Conclusion As compared to non-esports players, collegiate esports players were significantly less active and had a higher body-fat percentage, with lower lean body mass and bone mineral content. The BMIs showed no difference between the 2 groups. Esports athletes displayed significantly less activity and poor body composition, which are all correlated with potential health issues and risk of injury. BMI did not capture this difference and should not be considered an accurate measure of health in competitive esports players.

BACKGROUND: Ultrasound is an important tool to diagnose many clinical conditions. Yet hand-held devices may be prone to more data variability in part from the greater likelihood of human error. OBJECTIVE: Quantify intra-rater reliability of subcutaneous skin fold thickness from a hand-held ultrasound device. PARTICIPANTS: College-age subjects (18 men, 14 women) submitted to two sets of ultrasound subcutaneous skin fold measurements spaced (mean + sem) 10.6 + 2.2 days apart. Per measurement, they stood relaxed as ultrasound measured the subcutaneous skin fold thickness that covered their left leg’s calf muscle group. Measurements occurred with a hand-held device (BodyMetrix Pro System BX2000; Livermore, CA) used in accordance with the manufacturer’s guidelines. Four subcutaneous measurements were made 90∘ apart (anterior, medial, posterior, lateral) at the portion of the left calf with the largest circumference. To assess intra-rater reliability, we used intraclass correlation coefficients, limits of agreement, coefficient of variation and the smallest real difference. RESULTS: Intra-rater reliability was high for most of our statistical tests. CONCLUSION: Despite the relatively long period between measurements, our hand-held ultrasound device exhibited a high degree of intra-rater reliability. Given our results, ultrasound measurements may be a useful tool to quantify skin fold thickness.

BACKGROUND: The relationship between strength and throwing velocity is much investigated in handball, but core strength is largely ignored. Only four studies have investigated the effect of core training on handball throwing velocity, reporting conflicting results in amateur players. However, lack of specificity and deficient technical execution of throwing in amateurs can obscure the results. OBJECTIVE: To examine the direct association between trunk flexion strength and throwing velocity in elite handball players, using women as a model. METHODS: Sixteen women players from an elite-level Norwegian handball team participated in the study. Strength in trunk flexion, shoulder extension, internal shoulder rotation, and forearm pronation was assessed using isokinetic dynamometer measurements (peak moment, total work, angular impulse). Throwing velocity in both the standing throw with run-up and the jump throw was determined from motion capture measurements. To account for arm strength, the association between trunk flexion strength and throwing velocity was examined using partial correlation analyses. RESULTS: No significant association was found between any measure of trunk flexion strength and throwing velocity for either throwing technique (explained variance ⩽ 13.7%). CONCLUSIONS: The results indicate that isolated, dynamic trunk flexion strength is not a differentiating factor for handball throwing velocity in elite women players.

Objectives Individuals with myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) experience debilitating symptoms, including post-exertional malaise, an intensification of symptoms after physical or cognitive exertion. Previous studies found differences in the activity levels and patterns of activity among individuals with ME and CFS, compared to healthy controls; however, limited research exists on the activity levels of pediatric patients. The objective of this study was to examine differences in activity between healthy children and youth with ME and CFS. Methods The present study examines the objective (i.e., ActiGraphy) and self-reported levels of activity among children (ages 5 to 17) enrolled in a community-based study of pediatric CFS. Results Children with ME and CFS evidenced lower activity levels than healthy control children. Moreover, participants with ME and CFS evidenced increased nighttime activity and delayed initiation of daytime activity. Participants’ self-reported activity data significantly correlated with their ActiGraph data, suggesting that children with ME and CFS are able to accurately describe their activity level. Discussion This study highlights differences in activity level and diurnal/nocturnal activity patterns between healthy children and those with ME and CFS. These differences should be considered in identifying appropriate supports and accommodations for children with ME and CFS.

Osteochondral defect or osteochondritis dissecans (OCD) of the knee usually affects young, active populations. It is a challenging diagnosis as patients typically present with poorly localised activity-related pain, which is non-specific and covers many differentials. We present an active 11-year-old girl with bilateral osteochondral defects of the patellae: a rare clinical disorder which was affecting her sporting activities. She had a 12-month history of bilateral anterior knee pain before the diagnosis was achieved with appropriate imaging. Her pain significantly improved with activity modification and physiotherapy. Follow-up will require outpatient clinic assessment and imaging to determine if non-operative management continues to be successful or surgery may be required. This case report emphasises the importance of appropriate high index of suspicion when managing patients with non-specific knee pain. It also demonstrates the importance of judicious use of imaging to avoid a missed or delayed diagnosis.

Summary Background Functional performance tests serve to monitor the injured leg's resilience after anterior cruciate ligament injuries. The limb symmetry index greater than or equal to 90% represents an objective criterion to evaluate the knee function restoration and to return to sports. Aims The aim was to detect the point in time when limb symmetries and pre-injury levels of performance were restored, during the first year after surgery. Based on the data obtained, the proper moment for return to sport readiness was identified. Methods A 25-year-old female competitive gymnast performed a single-leg functional test battery. The study was conducted over 24 months and included one pre-injury and seven post-injury sessions. Results Inter-limb symmetries were restored at eight-ten months in all tests. Pre-injury performance levels were achieved at six months in two out of four tests. The single-leg hop for distance showed a performance decrease greater than 20% in the injured leg at twelve months. Conclusion Return to sport readiness was identified at ten months after surgery. Nevertheless, the restored inter-limb symmetry does not take into account performance decreases in the single-leg hop for distance and y-balance tests. Therefore, regular baseline assessments are recommendable to provide data for comparison and to optimise the decision-making process after injury.

This study examined the joint associations of sleep patterns and physical activity (PA) with all-cause, cardiovascular disease (CVD), and cancer mortality.A total of 341,248 adults (mean age = 39.7 years; men: 48.3%) were included in the study, with a 15-year follow-up. Participants reported sleep duration and disturbances (difficulty falling asleep, easily awakened, or use of sleeping medication). PA was classified into 4 levels:7.5, 7.5-14.9, 15.0-29.9, and ≥30.0 metabolic equivalent hours per week (MET-h/week). To understand the joint associations of sleep patterns and PA with mortality, Cox proportional hazard models were conducted, with exposure variables combining sleep duration/disturbances and PA.Compared with the reference group (sleeping 6-8 h/day), individuals who slept8 h/day had higher risk for all-cause mortality (hazard ratio (HR) = 1.307, 95% confidence interval (95%CI): 1.248-1.369), CVD mortality (HR = 1.298, 95%CI: 1.165-1.445), and cancer mortality (HR = 1.128, 95%CI: 1.042-1.220). Short sleep duration was not associated with mortality risk. Increased risk of all-cause and CVD mortality was found in participants who had difficulty falling asleep (HR = 1.120, 95%CI: 1.068-1.175; HR = 1.163, 95%CI: 1.038-1.304, respectively), and used sleeping medication (HR = 1.261, 95%CI: 1.159-1.372; HR = 1.335, 95%CI: 1.102-1.618, respectively) compared with those who slept well. Long sleep duration and sleep disturbances were not associated with risk of all-cause and CVD mortality among individuals achieving a PA level of ≥15 MET-h/week, and in particular among those achieving ≥30 MET-h/week.Long sleep duration, difficulty falling asleep, and use of sleeping medication were related to a higher risk of death. Being physically active at a moderate intensity for 25-65 min/day eliminated these detrimental associations.

Purpose: To examine the associations of accelerometer-derived steps volume and intensity with hospitalizations and all-cause mortality in older adults. Methods: This prospective cohort study involved 768 community-dwelling Spanish older adults (78.8 § 4.9 years, mean § SD; 53.9% females) from the Toledo Study for Healthy Aging (2012 2017). The number of steps per day and step cadence (steps/min) were derived from a hip-mounted accelerometer worn for at least 4 days at baseline. Participants were followed-up over a mean period of 3.1 years for hospitalization and 5.7 years for all-cause mortality. Cox proportional hazards regression models were used to estimate the individual and joint associations between daily steps and stepping intensity with hospitalizations and all-cause mortality. Results: Included participants walked 5835 § 3445 steps/day (mean § SD) with an intensity of 7.3 § 4.1 steps/min. After adjusting for age, sex, body mass index (BMI), education, income, marital status and comorbidities, higher step count (hazard ratio (HR) = 0.95, 95% confidence inter vals (95%CI: 0.90 1.00, and HR = 0.87, 95%CI: 0.81 0.95 per additional 1000 steps) and higher step intensity (HR = 0.95, 95%CI: 0.91 0.99, and HR = 0.89, 95%CI: 0.84 0.95 per each additional step/min) were associated with fewer hospitalizations and all-cause mortality risk, respectively. Compared to the group having low step volume and intensity, individuals in the group having high step volume and intensity had a lower risk of hospitalization (HR = 0.72, 95%CI: 0.52 0.98) and all-cause mortality (HR = 0.60, 95%CI: 0.37 0.98). Conclusion: Among older adults, both high step volume and step intensity were significantly associated with lower hospitalization and all-cause mortality risk. Increasing step volume and intensity may benefit older people.

Background It remains unclear whether studies comparing maximal oxygen uptake (VO2max) response to sprint interval training (SIT) vs. moderate-intensity continuous training (MICT) are associated with a high risk of bias and poor reporting quality. The purpose of this study was to evaluate the risk of bias and quality of reporting in studies comparing changes in VO2max between SIT and MICT. Methods We conducted a comprehensive literature search of 4 major databases: AMED, CINAHL, EMBASE, and MEDLINE. Studies were excluded if participants were not healthy adult humans or if training protocols were unsupervised, lasted less than 2 weeks, or utilized mixed exercise modalities. We used the Cochrane Collaboration tool and the CONSORT checklist for non-pharmacological trials to evaluate the risk of bias and reporting quality, respectively. Results Twenty-eight studies with 30 comparisons (3 studies included 2 SIT groups) were included in our meta-analysis (n = 360 SIT participants: body mass index (BMI) = 25.9 ± 3.7 kg/m2, baseline VO2max = 37.9 ± 8.0 mL/kg/min; n = 359 MICT participants: BMI = 25.5 ± 3.8 kg/m2; baseline VO2max = 38.3 ± 8.0 mL/kg/min; all mean ± SD). All studies had an unclear risk of bias and poor reporting quality. Conclusion Although we observed a lack of superiority between SIT and MICT for improving VO2max (weighted Hedge's g = −0.004, 95% confidence interval (95%CI): −0.08 to 0.07), the overall unclear risk of bias calls the validity of this conclusion into question. Future studies using robust study designs are needed to interrogate the possibility that SIT and MICT result in similar changes in VO2max.

Objective This cross-sectional study examined environmental correlates of sedentary behavior (SB) and physical activity (PA) in preschool children in the urban area of Tianjin, China. Methods Data were collected from the Physical Activity and Health in Tianjin Chinese Children study, involving healthy children 3–6 years old and their families. In all children (n = 980), leisure-time SB (LTSB) and leisure-time PA (LTPA) were reported in min/day by parents. In a subgroup (n = 134), overall sedentary time, light PA, and moderate-to-vigorous PA (MVPA) were objectively measured using ActiGraph accelerometry (≥3 days, ≥10 h/day). Environmental correlates were collected using a questionnaire that included home and neighborhood characteristics (e.g., traffic safety, presence of physical activity facilities) and children's behaviors. Potential correlates were identified using linear regression analysis. Results Multiple linear regression analysis showed that “having grandparents as primary caregivers” (βs and 95% confidence interval (CI) for overall sedentary time: 29.7 (2.1 to 57.2); LTSB (ln): 0.19 (0.11 to 0.28)) and “having a television (for LTSB (ln): 0.13 (0.00 to 0.25)) or computer (for LTSB (ln): 0.13 (0.03 to 0.23)) in the child's bedroom” were both associated with higher SB. Furthermore, “having grandparents as primary caregivers” was associated with less MVPA (β (95%CI): −7.6 (−14.1 to −1.2)), and “active commuting to school by walking” correlated with more MVPA (β (95%CI): 9.8 (2.2 to 17.4)). The path model showed that “more neighborhood PA facilities close to home” was indirectly related to higher LTPA (ln), which was partly mediated by “outdoor play” (path coefficients (95%CI): 0.005 (0.002 to 0.008)) and “going to these facilities more often” (path coefficients (95%CI): 0.013 (0.008 to 0.018)). Traffic safety was not a correlate. Conclusion Family structure and media exposure in the home maybe important factors in shaping preschoolers’ PA patterns. Built environmental correlates could indirectly influence preschoolers’ LTPA through parental help with engaging in active behaviors.

Background Evidence concerning the influence gender, age, and the time elapsed from the first dislocation to surgery in the outcomes of Medial Patella Femoral Ligament (MPFL) reconstruction are lacking. This systematic review was conducted to investigate whether patient characteristics have an influence in the clinical outcomes of MPFL reconstruction for patients with patellofemoral instability. Material and methods This study followed the PRISMA guidelines. The main databases were accessed in February 2021. All the studies reporting outcomes of primary MPFL reconstruction in patients with recurrent patellofemoral instability were considered for inclusion. A multivariate analysis diagnostic tool was used to analyse the association between age, gender and time from injury to surgery and the surgical outcomes at last follow-up. Results A total of 50 articles (2037 procedures) were included. The mean follow-up was 40.90 ± 24.8 months. The mean age was 23.6 ± 3.9 years. 64.3% (1309 of 2037 patients) were female. The mean time from injury to surgery was 64.5 ± 48.9 months. Women showed no statistically significant association with the Kujala score or complications. Older patients had a reduced risk to incur re-dislocations (P = 0.01) and revisions (P = 0.01). Longer time from injury to surgery was associated with greater risk to incur re-dislocations (P = 0.01), and with lower Kujala score (P Conclusion The time span from the first patellar dislocation to the surgical reconstruction was a negative prognostic factor, while sex had no influence on surgical outcomes. The role of patients age on surgical outcomes remains unclear.

BACKGROUND: Rotator cuff weakness is considered an important risk factor for shoulder injuries in volleyball. OBJECTIVE: To evaluate association of shoulder preseason strength status with shoulder injury occurrence in subsequent season. METHODS: Volleyball players (N= 181; 99 men) from Slovenian 1st and 2nd national league volunteered to participate in this prospective cohort study. Preseason isokinetic testing of the shoulder was conducted at 60∘/s in the concentric mode of contraction over a RoM of 60∘ with five repetitions of internal (IR) and external (ER) rotation. During the subsequent season the players reported shoulders injuries through a weekly questionnaire. RESULTS: During the season we have registered 14 (7.7%) shoulder injuries (10 in men). All injuries affected the dominant shoulder. There was significant preseason weakness of ER and lower ER/IR strength ratio in players with shoulder injury. Normal strength ratio ER/IR was a significant protective factor (Exp (B) = 0.217, 95% C.I. 0.058–0.811) for shoulder injury occurrence when controlled for sex and previous injury. CONCLUSIONS: The inclusion of systematic strengthening of the external rotators of the shoulder is necessary, especially for male volleyball players, as part of preventive measures for the prevention of shoulder injuries.

Category: Hindfoot Introduction/Purpose: To date, minimally invasive surgery (MIS) involving calcaneal osteotomy for Haglund deformity associated with intractable insertional Achilles tendinopathy has not been reported. This study presents the radiographic and clinical outcomes of our novel MIS-dorsal closing wedge calcaneal osteotomy (DCWCO) technique compared to open Haglund resection. We hypothesized that earlier clinical improvement after MIS-DCWCO could be achieved by leaving the Achilles tendon insertion site untouched. Methods: We retrospectively reviewed and compared the clinical and radiographic parameters of patients who underwent MIS- DCWCO (11 cases) or open Haglund resection (14 cases) between January 2012 and June 2019. The minimum duration of follow-up for inclusion was 18 months. We measured the calcaneal pitch, Meary's, Fowler-Philip, and Böhler's angles. Clinical outcomes were evaluated using the visual analogue scale (VAS) and Victorian Institute of Sports Assessment-Achilles (VISA-A) scores measured preoperatively and at 3, 6, 9, 12, and >=18 months, postoperatively. Results: In both groups, the Meary's and calcaneal pitch angles did not change significantly, whereas the Fowler-Philip and Böhler's angles were significantly changed postoperatively. Significant improvements in VAS and VISA-A scores were observed in both groups (P < .001). The extent of correction of the four radiographic and two clinical parameters were not significantly different between the two groups. However, VAS and VISA-A scores at postoperative 6 months were significantly different, whereas these parameters were not significantly different at all other time points. Conclusion: Both techniques provided similar postoperative clinical and radiographic improvement. However, MIS-DCWCO achieved earlier clinical improvement than open Haglund resection.

Highlights • A risk-benefit analysis was performed to estimate the optimal outdoor moderate physical activity (MPA) duration under varying particulate matter (PM2.5) concentrations. • An inverse nonlinear relationship was identified between optimal MPA duration and background PM2.5 concentration levels. • The relationship between optimal MPA duration and background PM2.5 concentration levels was stronger when exercising at a location closer to a source of air pollution. • Compared to the general adult population, adults aged 60 years and older had substantially steeper curves. • The health benefit of outdoor MPA by far outweighs the health risk of PM2.5 pollution for the global average urban background concentration., Objective Outdoor physical activity (PA) brings important health benefits, but exposure to polluted air increases health risks. This study aimed to quantify the tradeoff of PA under fine particulate matter (PM2.5) air pollution by estimating the optimal PA duration under various pollution levels. Methods A risk-benefit analysis was performed to estimate the optimal outdoor moderate PA (MPA) duration under varying PM2.5 concentrations. Results An inverse nonlinear relationship was identified between optimal MPA duration and background PM2.5 concentration levels. When background PM2.5 concentration increased to 186 µg/m3, the optimal outdoor MPA duration decreased to 2.5 h/week, the minimum level recommended by current PA guidelines. When background PM2.5 concentration further increased to 235 µg/m3, the optimal outdoor MPA duration decreased to 1 h/week. The relationship between optimal MPA duration and background PM2.5 concentration levels was stronger when exercising at a location closer to a source of air pollution. Compared to the general adult population, adults aged 60 years and older had substantially steeper curves—the optimal outdoor MPA duration decreased to 2.5 h/week when background PM2.5 concentration reached 45 µg/m3. Conclusion The health benefit of outdoor MPA by far outweighs the health risk of PM2.5 pollution for the global average urban background concentration (22 μg/m3). This modeling study examined a single type of air pollutant and suffered from measurement errors and estimation uncertainties. Future research should examine other air pollutants and indoor PA, incorporate short- and mid-term health effects of MPA and air pollution into the risk-benefit analysis, and provide estimates specific for high-risk subgroups., Graphical Abstract Image, graphical abstract

International audience; Purpose: No therapeutic consensus has been established about proximal ruptures of the rectus femoris muscle. The objective of this literature review is to determine a therapeutic course of action. Methods: We conducted a literature review on the PubMed database using the following keywords (in French and English, respectively): "quadriceps/quadriceps", "droit ant erieur/rectus femoris", "proximal/ proximal", "chirurgie/surgical", "avulsion/avulsion". We collected 266 articles, 36 of them were selected, which were related to our topic: proximal rupture of the anterior rectus femoris. Patients with a proximal rupture of the rectus femoris, minor or major patient of traumatic origin were included in this study. Patients injured at another lesion level, or non-traumatic lesions of the proximal rectus femoris (tendinitis without ruptures, tumor or others) were excluded. For each patient, the indications, the type of treatment and the functional result were analyzed, with the time to recovery and the level of recovery from sports and professional activities (same sport/profession or not, same level or not) as the main criterion of judgment. Fisher exact test was used for statistical comparison. Results: The aims of conservative treatment are to be pain free for the patient, to fight hematoma and to rehabilitate the injury as quickly as possible. The surgical techniques are varied, with most consisting of either a reinsertion of the musculo-tendon stump or a resection of the scar tissue with myo-tendinoaponeurotic suture in place. The functional results are good for the majority of the treatments proposed, but the conservative treatment has a shorter recovery time (3 months vs. 4 months for the best surgical results). Highly displaced bone avulsion is the only indication for first-line surgical treatment. Conclusion: The main disadvantage of conservative treatment is the risk of residual pain beyond 3 months (10%), justifying an MRI to guide secondary surgical treatment. We propose a treatment plan for proximal rupture of the proximal rectus femoris rupture.

Background This study aimed to assess the clinical and radiographic outcomes of different surgical procedures in atraumatic osteochondrosis dissecans (OCD) of the talus in youth and adolescence. Methods 32 joints in 30 patients (mean age 14.7 ± 2.2 years) were evaluated. Numeric Rating Scale (NRS), Foot and Functional Index (FFI), American Orthopedic Foot and Ankle Society ankle-hindfoot score (AOFAS), Pediatric Outcome Data Collection Instrument (PODCI), and sport participation were recorded. We compared preoperative and follow-up ankle radiographs to identify specific features in the OCD morphology and any signs of joint degeneration. Results After a median follow-up period of 72.5 months the drilling group showed significantly better scores than the combined fixation and reconstruction groups (AOFAS, p = 0.024; PODCI, p = 0.003; NRS, p = 0.027). Signs of joint degeneration were observed in 50% of all ankles, especially in those treated by OCD-fixation and reconstruction. Conclusions Advanced fixation and reconstruction procedures in unstable and non-salvageable atraumatic talar OCD resulted in inferior clinical scores and a higher prevalence of joint degeneration than drilling procedures in stable OCD in young patients.

Long-distance running is a demanding sport and runners use a variety of coping strategies to deal with these demands. In this study, we investigated running-related demands, resources, and recovery and, as an indicator of well-being, vigor. Specifically, following the Demand-Induced Strain Compensation Recovery Model, we tested to what degree the relation between running-related demands and vigor was moderated by two coping strategies available in running: running-related resources (e.g., training control, running mate/coach support) and running-related recovery (i.e., detachment from running). Demands, resources, recovery, and vigor were all surveyed across three separate dimensions (i.e., physical, cognitive, emotional) in a cross-sectional sample of 623 recreational long-distance runners. Hierarchical regression analyses were used to determine to what degree the demands-vigor relation was moderated by resources and recovery. Evidence for moderations was found for the cognitive and emotional dimensions of vigor, revealing four significant moderating effects of resources or recovery on the demands-vigor relation. Three of these effects involved emotional resources or recovery. Contrary to expectations, results also showed that in two cases higher recovery was associated with lower vigor, rather than higher, when runners experienced high demands. In all, we found modest support for the role of resources and recovery in altering the nature of the demands-vigor relation in recreational long-distance runners. This study highlights the importance of the emotional dimension of demands, resources, and recovery, as those facets were most important in predicting vigor in runners. Practical implications are addressed with regard to emotional resources and recovery for long-distance runners.

Background After experiencing an unexpected slip perturbation, individuals’ behavioral performance can be classified into three categories: recovery, feet-forward fall, and split fall. Researchers are uncertain whether these differences in slip outcomes are due to distinct strategies or part of a single strategy. Research question Whether older adults with different behavioral outcomes during their novel slip have different kinematic synergies? Methods The kinematic synergies were extracted from segment angles in 87 participants using principal component analysis (PCA). The first two principal components (PC1 and PC2) in pre-slip, early-reactive, and late-reactive phases were compared across different slip outcomes. Results Results showed that the kinematic synergies in pre-slip and early-reactive phases are highly consistent among the three outcomes (recovery, split fall, and feet-forward fall). For the late-reactive phase, both split falls and feet-forward falls showed different kinematics synergies from recoveries. Significance Our findings indicated that a single strategy might be used for different slip outcomes in the pre-slip and early-reactive phases, while distinct strategies were used by fallers compared to recovered individuals. Specifically, larger trunk flexion in pre-slip phase, larger knee flexion and plantar flexion of the slipping limb in both early-reactive and late-reactive phase, and larger knee extension of the recovery limb in late-reactive phase would lower the fall risk. This study would help to assess the vulnerabilities in control strategy, according to which individualized treatment could be provided to reduce predisposition to specific types of falls.

Background Variability in gait speed is influenced by age and health status. However, no study has investigated the effects of different instructions on gait speed. Research question This study investigated how walking prompts contributed to variability in gait speed. Methods Participants walked on a pressurized walkway. Gait speed variability was assessed using multilevel modeling. Results 61% of the variance in gait speed was due to instruction, while 14% was due to individual differences. Significance Reference values for gait speed across a number of prompts will be highly useful for assessing gait performance in young adults. Further, the instruction given produces a large amount of variability in selected walking speed. This finding urges researchers to maintain consistency when delivering walking instructions.

Background Diabetic retinopathy is a principal cause of visual damage and blindness, in which laser treatment offers proven therapy. The progressive degeneration of the retina, secondary to diabetes, is believed to cause postural instability although this is not well documented. The aim of this research was to assess how optic flow stimuli contribute to the control of stance in people with impaired retinal functions. Research question Does the different retinal functionality correspond to different specific patterns of movements and muscles recruitment? Methods Postural mechanisms and motor strategies were measured by testing subjects in quiet stance on a force platform with surface electromyography under different optic flow stimulations. Root mean square values of the center of pressure time-varying signals and normalized EMG values were used to evaluate the postural sway. Results People with diabetic retinopathy, and to a greater extent laser group, were more unstable than healthy subjects. The greater amplitude of the body sway observed in the retinopathy group, and especially in the laser group, could be an expression of the difficulty for this population in processing this kind of visual information. Significance The increase in muscle activity indicates that there are musculoskeletal and postural changes in the lower limb musculature with increasing severity of diabetic retinopathy. An impaired retinal function might negatively affect postural control in a way that is dependent on the severity of retinal damage.

A systematic review was conducted comparing patient reported outcomes measures (PROMs), functional scores, and the rate of complications between arthroscopic and open treatment for femoroacetabular impingement (FAI) at mid-term follow-up.This systematic review was performed according to the PRISMA guidelines. The literature search was performed in October 2020. All clinical trials treating FAI using open osteoplasty or arthroscopic surgery were considered for inclusion. Only articles reporting12 months follow-up were included.Data from 97 articles (9981 procedures) were collected. At a mean 19.2 months follow-up there was no difference between the two cohorts. At a mean follow-up of 38 months, the external rotation was increased in the arthroscopic group (P 0.0001). The modified Harris Hip Score scored greater in favour of the open osteoplasty group (P = 0.04), as did the Hip Outcome Score - Activities of Daily Living subscale (P = 0.01). At a mean 45.1 months the arthroscopic group presented greater external rotation (P 0.0001) and SF-12 Mental (P = 0.04). The modified Harris Hip Score was greater in favour of the open osteoplasty group (P = 0.03), as was the HOS-ADL (P = 0.01). Regarding complications, the arthroscopic group experienced lower rates of subsequent revisions (P 0.0001).Based on the significant reduction of revisions-rate and significant increase in range of motion, arthroscopy treatment for the management of FAI may be recommended.

Background Gait abnormalities from neuromuscular conditions like cerebral palsy (CP) limit mobility and negatively affect quality of life. Increasing walking speed and stride length are essential clinical goals in the treatment of gait disorders from CP. Research question. How does over-ground gait training with an untethered ankle exoskeleton providing adaptive assistance affect mobility-related spatiotemporal outcomes and lower-extremity muscle activity in people with CP? Methods A diverse cohort of individuals with CP (n = 6, age 9–31, Gross Motor Function Classification System Level I – III) completed four over-ground training sessions (98 ± 17 min of assisted walking) and received pre- and post-training assessments. On both assessments, participants walked over-ground with and without the exoskeleton while we recorded spatiotemporal outcomes and muscle activity. We used two-tailed paired t-tests to compare all parameters pre- and post-training, and between assisted and unassisted conditions. Results Following training, walking speed increased 0.24 m/s (p = 0.006) and stride length increased 0.17 m (p = 0.013) during unassisted walking, while walking speed increased 0.28 m/s (p = 0.023) and stride length increased 0.15 m (p = 0.002) during exoskeleton-assisted walking. Exoskeleton training improved stride-to-stride repeatability of soleus and vastus lateralis muscle activation by up to 51 % (p ≤ 0.046), while the amount of integrated stance-phase muscle activity was similar across visits and conditions. Relative to baseline, post-training walking with the exoskeleton resulted in a soleus activity pattern that was 39 % more similar to the typical pattern from unimpaired individuals (p Significance This study demonstrates acute spatiotemporal and neuromuscular benefits from over-ground training with adaptive ankle exoskeleton assistance, and provides rationale for completion of a longer randomized controlled training protocol.

In team sports, it has been found that team mistakes were reported as a stressor by both males and females, and at every playing level (e.g., club, university, national). The purpose of this study was to examine the impact of partners’ play on performance, emotions, and coping of doubles racquet sport athletes. Seventeen one-on-one semistructured interviews were conducted over the course of 6 months. Inductive and deductive analysis produced the main themes of overall impact on performance (i.e., positive, negative, or no impact), negative emotions (i.e., anger), positive emotions (i.e., excitement), emotion-focused coping (i.e., acceptance), and problem-focused coping (i.e., team strategy). These athletes acknowledge that how their partner plays significantly affects not only their emotions but also their own play and their choice of coping strategies. Future research should try to understand which forms of coping reduce the impact of partners’ play.

Background Previous studies have determined the videos on YouTube® have misleading information in medicine, however the assessment of the information for hallux valgus surgery is lacking. Methods YouTube® was analyzed using two keywords as ‘hallux valgus surgery’ and ‘bunion surgery’. Once redundancies were eliminated, each video was evaluated for the characteristic as following: duration, number of views, likes and dislikes, days since upload, view and like ratios and video power index (VPI). The quality of the information was evaluated using DISCERN, JAMA and Hallux Valgus Score (HVS). Results A total of 49 videos included. Fair or poor results for DISCERN and HVS (90% and 69% of videos, respectively) were found. No difference was found between video source and quality scores. Number of likes and VPI negatively correlated with all scores (p Conclusions YouTube® had poor quality of information for hallux valgus surgery.

BACKGROUND: Severe acetabular bone loss in revision total hip arthroplasty (RTHA), both with or without pelvic discontinuity, remains a great challenge in orthopaedic surgery. OBJECTIVE: The aim of this study was to evaluate risk factors for failure of custom-made acetabular implants in RTHA. METHODS: Seventy patients with severe acetabular bone loss (Paprosky Type III) and pelvic discontinuity, who required RTHA, were included in our study. All prostheses were constructed based on a thin-layer computed-tomography (CT) scan of the pelvis. The treatment was considered unsuccessful in the event of periprosthetic joint infection (PJI) or aseptic loosening (AL) with need for explantation of the custom-made acetabular implant. RESULTS: The average follow-up was 41.9 ± 34.8 months (range 1.5–120). Implant survival at last follow-up was 75.7% (53 of 70). Explantation was necessary in 17 cases (15 PJI; 2 AL). Previous PJI as reason for RTHA (p= 0.025; OR 3.56 (95% CI: 1.14; 11.21)), additional revision of femoral components (p= 0.003; OR 8.4 (95% CI: 1.75; 40.42)), rheumatoid disease (p= 0.039; OR 3.43 (95% CI: 1.01; 11.40)), elevated preoperative CRP > 15.2 mg/l (p= 0.015; AUC: 0.7) and preoperative haemoglobin < 10.05 (p= 0.022; AUC: 0.69) were statistically significant risk factors associated with treatment failure. Age and BMI were not statistically significant contributing to implant failure. CONCLUSION: Risk factors for treatment failure were a previous PJI, additional revision of femoral component, rheumatoid disease, elevated preoperative CRP and low preoperative haemoglobin. Awareness of these risk factors will help to improve future treatment standards.

Objective Soccer match-play is typically contested over 90 min; however, in some cup and tournament scenarios, when matches are tied, they proceed to an additional 30 min, which is termed “extra-time” (ET). This systematic review sought to appraise the literature available on 120-min of soccer-specific exercise, with a view to identifying practical recommendations and future research opportunities. Methods The review was conducted according to the PRISMA guidelines. Independent researchers performed a systematic search of PubMed, CINAHL and PsycINFO in May 2019, with the following keywords entered in various combinations: “soccer”, “football”, “extra-time”, “extra time”, “120 minutes”, “120 min” “additional 30 minutes”, and “additional 30 min.” Results The search yielded an initial 73 articles. Following the screening process, 11 articles were accepted for analyses. Articles were subsequently organized into the following 5 categories: movement demands of ET, performance responses to ET, physiological and neuromuscular response during ET, nutritional interventions, and recovery and ET. The results highlighted that during competitive match-play, players cover 5%–12% less distance relative to match duration (i.e., meters per minute) during ET compared to the preceding 90 min. Reductions in technical performance (i.e., shot speed, number of passes and dribbles) were also observed during ET. Additionally, carbohydrate provision may attenuate and improve dribbling performance during ET. Moreover, objective and subjective measures of recovery may be further compromised following ET when compared to 90 min. Conclusion Additional investigations are warranted to further substantiate these findings and identify interventions to improve performance during ET.

Background Modular organization in muscular control is generally specified as synergistic muscle groups that are hierarchically organized. There are conflicting perspectives regarding modular organization for regulation of walking speeds, with regard to whether modular organization is relatively consistent across walking speeds. This conflict might arise from different stride time (time for one stride) and stride length combinations for achieving the same walking speed. Research question Does the regulation of the modular organization depend on stride time and stride length (stride time-length) combinations? Methods Ten healthy men walked at a moderate speed (nondimensional speed = 0.4) on a treadmill at five different stride time-length combinations (very short, short, preferred, long, and very long). Surface electromyograms from 16 muscles in the trunk and lower limb were recorded. The modular organization was modeled as muscle synergies, which represent groups of synchronously activated muscles. Muscle synergies were extracted using a decomposition technique. The number of synergies and their activation durations were analyzed. Results The number of synergies was consistent in the preferred and quasi-preferred condition (median: 4.5 [short], 4.5 [preferred], 5 [long]), while it varied in the extreme condition (median: 4 [very short] and 6 [very long]; 0.02 ≤ p ≤ 0.09). Gait parameters (stride time, stride length, stance time, swing time, and double stance time) were significantly different for preferred and quasi-preferred conditions (p Significance Our results provide additional insights on the flexibility of modular control during walking, namely that the number of synergies or activations are fine-tuned even within one walking speed. Our finding implies that a variety of walking patterns can be achieved by consistent synergies except for extreme walking patterns.

This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Fifteen trained male runners (10-km time of44 min) performed 10-km runs at 90% of their individual speed at lactate threshold (i.e., when change in lactate exceeded 1 mmol/L during an incremental running test) in a control and stiff shoe condition on 2 occasions. Lower limb joint kinematics and kinetics were measured using a motion capture system and a force-instrumented treadmill. Data were acquired every 500 m.Prolonged running resulted in a redistribution of positive joint work from distal to proximal joints in both shoe conditions. Compared to the beginning of the run, less positive work was performed at the ankle (approximately 9%; p ≤ 0.001) and more positive work was performed at the knee joint (approximately 17%; p ≤ 0.001) at the end of the run. When running in the stiff shoe condition, the onset of joint work redistribution at the ankle and knee joints occurred at a later point during the run.A delayed onset of joint work redistribution in the stiff condition may result in less activated muscle volume, because ankle plantar flexor muscles have shorter muscles fascicles and smaller cross-sectional areas compared to knee extensor muscles. Less active muscle volume could be related to previously reported decreases in metabolic cost when running in stiff footwear. These results contribute to the notion that footwear with increased stiffness likely results in reductions in metabolic cost by delaying joint work redistribution from distal to proximal joints.

According to the Leadership Efficacy Model, leadership efficacy depends on leaders’ tendency to make linear relationships between leadership philosophy, practice, and criteria (i.e., congruence of leadership cycles). Moreover, efficacy increases if coaches make these linear relationships by using the optimal leadership profile and by considering the antecedent factors of leadership (characteristics of the leader, team members, and organizational conditions; i.e., favorability of conditions for leadership). This study compared the perceptions of athletes and their coaches regarding leadership cycles, and tested the moderator role of optimal leadership profile and leadership favorability in the relationship between leadership cycles and leadership efficacy. This study included 92 football athletes (ages less than 17 and 19 years) and respective coaches (n = 5). The evaluation protocol included measures of leadership cycles, leadership styles, leadership favorability, and sport performance perception. Athletes and coaches agreed on coaches’ need to increase their practice and criteria, but athletes also considered that coaches should better clarify their philosophy. Regression analyses confirmed that leadership congruency predicts higher perceptions of team performance in athletes. Moreover, optimal leadership profile and higher leadership favorability were associated with higher team and individual performance. However, these two factors did not moderate the relationship between leadership congruency and efficacy.

There is a body of research that indicates the need for community-driven and culturally responsive pedagogies in sport-based interventions. There is much to learn from the pedagogical approaches and experiences of African Australian refugee-background coaches who work with refugee-background young people toward acceptance and affirmation of their cultural and racial identities. This paper explores African Australian refugee-background coaches’ pedagogies in working with African Australian refugee-background young people in a grassroots football programme in Melbourne. Participants included an African Australian refugee-background young woman and four coaches. Data collection spanned a six-month period and included observations and semi-structured interviews. The findings were analysed using Ladson-Billings’ [Ladson-Billings, G. (1995b). Toward a theory of culturally relevant pedagogy. American Educational Research Journal, 32(3), 465–491. https://doi.org/10.3102/00028312032003465; Ladson-Billings, G. (2009). The dreamkeepers : Successful teachers of African American children. Jossey-Bass Publishers; Ladson-Billings, G. (2014). Culturally relevant pedagogy 2.0: A.k.a. The Remix. Harvard Educational Review, 84(1), 74–84. https://doi.org/10.17763/haer.84.1.p2rj131485484751] conceptualisation of Culturally Relevant Pedagogy. The study identified three main themes. First, the coaches considered themselves ‘barrier breakers’: they were able to connect the African Australian refugee-background young people to different resources in and outside of sports contexts to develop their success in football and in life. Second, the coaches considered the sport programme ‘a family’ where they were willing to nurture and support cultural competence by sharing power with the participants and their community. Third, the coaches created spaces for young people to develop awareness that allowed them to critique some of the social inequities experienced. Future studies should continue to move beyond a focus on predominantly white and middle-class providers and coaches in sport-based interventions. By including and foregrounding the voices of coaches who have diverse experiences, more diverse cultural knowledges are validated, enabling the translation of this knowledge into more culturally responsive sport programmes.

This study aimed to investigate whether there is a systematic change of leg muscle activity, as quantified by surface electromyography (EMG), throughout a standard running footwear assessment protocol at a predetermined running speed.Thirty-one physically active adults (15 females and 16 males) completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s. The level of muscle activity from 6 major leg muscles was recorded using surface EMG. The variables assessed were the EMG total intensity as a function of time and the cumulative EMG overall intensity. Systematic effects of the chronological testing round (independent variable) on the normalized EMG overall intensity (dependent variable) were examined using Friedman analysis of variates and post hoc pairwise Wilcoxon signed-rank tests (α = 0.05).There was a systematic reduction in overall EMG intensity for all 6 muscles over the time course of the running protocol (p0.001) until the fourth testing round when EMG intensities reached a steady state. The one exception was the biceps femoris muscle, which showed a significant reduction of EMG intensity during the stance phase (p0.001) but not the swing phase (p = 0.16).While running at a predetermined speed, the neuromuscular system undergoes an adaptation process characterized by a progressive reduction in the activity level of major leg muscles. This process may represent an optimization strategy of the neuromuscular system towards a more energetically efficient running style. Future running protocols should include a familiarization period of at least 7 min or 600 strides of running at the predetermined speed.

BACKGROUND: Pulse oximetry measures heart rate (HR) and percent oxygen saturation (SpO2). For aerobic exercise, whereby cellular oxygen demand and delivery are elevated and maintained for extended periods, HR and SpO2 values are consistent when measured by pulse oximetry. Yet due to its intermittent nature, HR and SpO2 values from resistive exercise may exhibit lower data reliability and repeatability. OBJECTIVE: Assess intra-rater reliability and repeatability of pulse oximetry HR and SpO2 values from two identical resistive exercise protocols. METHODS: Subjects (n= 32) performed two calf press workouts on a flywheel-based ergometer as HR and SpO2 were measured before, between sets, and after exercise. Workouts entailed a 4-set 15-repetition protocol separated by 120-second rests. Intra-rater reliability was assessed with intraclass correlation coefficients (ICC). Repeatability was measured by the smallest real difference in absolute and relative terms. RESULTS: ICC and standard error of estimate results for HR ranged from 0.60–0.79 and 9.1–13.0 respectively. SpO2 ICC and standard error of estimate results ranged from 0.16–0.71 and 1.44–4.33 respectively. Between sets, smallest real difference values tended to be less for HR. CONCLUSIONS: Results demonstrate acceptable intra-rater reliability and repeatability for HR, but not SpO2 which we attribute to the exercise mode and protocol examined.

BACKGROUND: Vibration training can affect strength improvement. However, the role of the vibration frequency, in terms of knee muscle strength, is unclear. OBJECTIVE: To evaluate the effect of vibration training with the same amplitude and different frequencies on the isokinetic muscle strength of the knee in juvenile football players. METHODS: Juvenile football players were divided into four groups: low frequency (n= 13, 25 Hz), medium frequency (n= 14, 40 Hz), high frequency (n= 14, 50 Hz), and control (n= 13). The frequency groups completed 12 weeks of weight-free vibration training (three times/week) with the same amplitude (3 mm) but different frequency. RESULTS: Compared with baseline, the peak extension torque of the knee at 60∘/s and 240∘/s increased by 8.4% and 12.9%, respectively, in the medium-frequency group, and by 8.9% and 15.5%, respectively, in the high-frequency group. The extensor endurance (the ability of joint muscle groups to maintain a force output over time) of the knee in the high-frequency group increased by 4.3%. At 12 weeks, the high-frequency group had greater knee extensor endurance than the low- and medium-frequency groups. CONCLUSION: In juvenile football players, weight-free vibration training at 40 Hz and 50 Hz improves peak torque of the knee extensors at 60∘/s and 240∘/s, while training at 50 Hz improves endurance of the knee extensors.

BACKGROUND: Bilateral strength asymmetry and fatigue predispose athletes to various injuries and conventional methods appear to be poor predictors of lower extremity muscular performance under NF conditions. OBJECTIVE: The purpose of the study was to compare the conventional Hcon/Qcon (HQR) ratio and the dynamic control ratio (DCR: Hecc/Qcon) under non-fatiguing (NF) and fatiguing (F) conditions and verify the effects of heavy-intensity constant running and cycling exercise on the isokinetic performance. METHODS: Twenty healthy male participants performed running and cycling VO2max at work-rate associated with the achievement of VO2max (TTE). Isokinetic muscle strength performance was tested at 60 and 180∘/s before and after these sessions with 48-hour intervals. Quadriceps (QFR) and hamstring (HFR) muscle fatigue rates were also calculated during these sessions. Blood lactate concentration was measured before and two-minutes after running and cycling TTE. RESULTS: No between-condition differences were found for the HQR while the DCR decreased significantly at 180∘/s following cycling and running sessions (p< 0.05). Cycling TTE was positively correlated with in dominant (r= 0.535, p= 0.015) and non-dominant (r= 0.446, p= 0.048) QFR. Positive correlations were also found between running TTE and dominant (r= 0.500, p= 0.25) and non-dominant (r= 0.465, p= 0.039) HFR. CONCLUSIONS: The DCR obtained at fast angular velocities following a strenuous exercise seems to be the best indicator of muscle performance while its assessment under F conditions reveals higher ratios compared to NF conditions and conventional methods.

BACKGROUND: Some recovery strategies are needed to reduce or eliminate the effect of negative symptoms caused by exercise. OBJECTIVE: The aim of this study was to determine the effect of different types of recovery after single-bout strength exercises on biomarkers of muscle damage, cytokine release and lactate elimination. METHODS: Following familiarization, 10 male volunteers performed four randomized recovery protocols (passive or active recovery with or without compression garments) following a single bout of resistance exercise (squat and deadlift exercises). The blood creatine kinase (CK), lactate dehydrogenase (LDH), interleukine-6 (IL-6), and tumor necrosis factor-alfa (TNF-α) values were measured before and after exercise, and after 24, 48, 72 hours. RESULTS: The CK analysis showed that all protocols significantly increased (p< 0.05) CK activity compared to the pre and 24 h post time points. Interestingly, protocol 3 and 4 significantly decreased (p< 0.05) CK activity compared 24 and 72 h post-exercise. LDH, IL-6, and TNF values did not show significant difference (p> 0.05) at the time points tested. CONCLUSIONS: Active recovery is an effective method for reducing the severity and duration of muscle damage and for accelerating the clearance of blood lactate (BLa) following a single bout of strength training. There is no added benefit of using compression garments.