High Sport Specialization Is Associated With More Musculoskeletal Injuries in Canadian High School Students.

OBJECTIVE: To describe levels of sport specialization in Canadian high school students and investigate whether sport specialization and/or sport participation volume is associated with the history of musculoskeletal injury and/or concussion. DESIGN: Cross-sectional study. SETTING: High schools, Alberta, Canada. PARTICIPANTS: High school students (14-19 years) participating in various sports. INDEPENDENT VARIABLES: Level of sport specialization (high, moderate, low) and sport participation volume (hours per week and months per year). MAIN OUTCOME MEASURES: Twelve-month injury history (musculoskeletal and concussion). RESULTS: Of the 1504 students who completed the survey, 31% were categorized as highly specialized (7.5% before the age of 12 years). Using multivariable, negative, binomial regression (adjusted for sex, age, total yearly training hours, and clustering by school), highly specialized students had a significantly higher musculoskeletal injury rate [incidence rate ratio (IRR) = 1.36, 95% confidence interval (CI), 1.07-1.73] but not lower extremity injury or concussion rate, compared with low specialization students. Participating in one sport for more than 8 months of the year significantly increased the musculoskeletal injury rate (IRR = 1.27, 95% CI, 1.02-1.58). Increased training hours significantly increased the musculoskeletal injury rate (IRR = 1.18, 95% CI, 1.13-1.25), lower extremity injury rate (IRR = 1.16, 95% CI, 1.09-1.24), and concussion rate (IRR = 1.31, 95% CI, 1.24-1.39). CONCLUSIONS: Approximately one-third of Canadian high school students playing sports were categorized as highly specialized. The musculoskeletal injury rate was higher for high sport specialization students compared with low sport specialization students. Musculoskeletal injuries and concussion were also more common in students who train more and spend greater than 8 months per year in one sport.

Sport concussion assessment in New Zealand high school rugby players: a collaborative approach to the challenges faced in primary care.

PRIMARY OBJECTIVE: To describe the collaborative development of a New Zealand Rugby Concussion Assessment (NZRCA) for primary care and to provide normative baseline data from a representative group of high school rugby players. METHODS: This study, conducted over the 2018 and 2019 community rugby season where players were baseline tested during the pre- or start of season period. RESULTS: Data were collected from 1428 players (males n = 1121, females n = 307) with a mean age of 15.9 ± 1.4 years. The mean ± SD symptom severity score was 11.3 ± 8.6, the mean number of endorsed symptoms was 8.5 ± 5.3 and the percentage feeling "normal" was 80.2 ± 15.3%. Only 5.3% of players reported no symptoms at baseline. The most common reported were: 'distracted easily' (72.5%), 'forgetful' (68.5%), and 'often tired' (62.6%). None of the participants achieved a perfect score for the SAC50. The majority of participants (89.7%) passed the tandem gait test with a time of 12.2 ± 1.7 seconds. Age, gender, and ethnicity were associated with NZRCA performance; albeit weakly. CONCLUSION: This study provides normative reference values for high-school rugby players. These data will aid healthcare providers in their identification of suspected concussion in the absence of individualized baselines.

Time to expand the circle of care - General practitioners' experiences of managing concussion in the community.

New Zealand Rugby (NZR) implemented a concussion management pathway (CMP), aimed at improving management at community level. General Practitioners (GPs) played a large role in the design of this process. The objective of this study was to explore GPs' perceptions of barriers and facilitators of the CMP and rugby-related concussion management in the community. A descriptive qualitative approach using interviews and focus groups was employed. Four themes were derived: i) GPs' existing knowledge and confidence around concussion management; ii) Operational resources: time, remuneration and pathway guidance; iii) Standardising concussion care and iv) Expanding the circle of care - the need for multi-disciplinary healthcare team. These themes described how GP's concussion knowledge, and the efficiency and availability of operational resources affected their experience and ability to fulfil their tasks within the CMP. GPs found NZR's CMP especially valuable, as it provided guidance and structure. Expanding the role of other healthcare providers was seen as critical to reduce the burden on GPs, while also delivering a more holistic experience to improve clinical outcomes. Addressing the identified barriers and expanding the network of care will help to improve the ongoing development of NZR's CMP, while supporting continued engagement with all stakeholders.

Relationship Between Strength, Athletic Performance, and Movement Skill in Adolescent Girls.

ABSTRACT: Sommerfield, LM, Harrison, CB, Whatman, CS, and Maulder, PS. Relationship between strength, athletic performance, and movement skill in adolescent girls. J Strength Cond Res 36(3): 674-679, 2022-Muscular strength in youth has been linked to health and physical benefits, enhanced movement skill, and an active lifestyle in adulthood. However, the relationship between maximum strength, athletic performance, and movement skill in youth females remains unclear. The purpose was to examine the relationship between maximum strength, athletic performance, and movement skill and determine whether differences exist between strong girls (SGs), average girls (AGs), and weak girls (WGs). One hundred four girls (age 14.0 ± 0.6 years, height 162.6 ± 5.9 cm, body mass 57.3 ± 9.7 cm) from a girls' secondary school performed an isometric midthigh pull (IMTP), double- and single-leg (right leg = R, left leg = L) countermovement jump, 10- and 20-m sprints, a drop vertical jump ,and the back squat assessment. Significance was set at p < 0.01 for correlations and p < 0.05 for one-way analysis of variance. Correlations revealed IMTP had significant small to large relationships with all performance variables (r = 0.27-0.62) except right-leg countermovement jump and left-leg countermovement jump height (r = 0.17-0.23). Relative IMTP had significant moderate to large relationships with all performance variables (r = 0.32-0.60). There were significant differences between strength groups for all performance measures. Strong girls had significantly faster sprint times than AGs. In addition, SGs and AGs performed significantly better than WGs in all assessments. The results of this study demonstrate the importance of strength for athletic performance and movement skill in adolescent girls.

Baseline concussion assessment performance of community-based senior rugby players: a cross-sectional study.

OBJECTIVE: To report pre-season baseline concussion assessment performance among senior rugby players and explore associations between assessment performance and player demographics. DESIGN: A cross-sectional study using the New Zealand Rugby Concussion Assessments (NZRCA), comprising symptom, cognitive and dynamic coordination assessments was conducted in the 2018-2019 season. METHODS: Players' baseline assessments were characterised using descriptive statistics; effect sizes (ES) and t-tests were used to explore associations between player demographic characteristics and NZRCA performance. RESULTS: A total of 733 players (11.4% female) aged between 16 and 52 years completed the NZRCA. The median (range) value for symptom severity, endorsed symptoms and "percentage normal" was respectively, 5 (0-40), 5 (0-21) and 90% (30-100%). A perfect standardised assessment of concussion score was achieved by one participant; seven achieved ≥27/30 for immediate recall, and 22 achieved a perfect delayed recall score. Most participants (n = 674, 92%) passed the tandem gait test. Associations between NZRCA performance and gender, concussion history, and Pasifika ethnicity were observed with effect sizes ranging from small (0.18) to large (0.70). Six hundred and twenty-three (85%) participants reported at least one symptom. CONCLUSIONS: The results from this study could help support decision-making by clinicians, improving the management of concussions in the community setting.

What they know and who they are telling: Concussion knowledge and disclosure behaviour in New Zealand adolescent rugby union players.

The purpose of this study was to survey high school rugby players from a range of ethnic, geographic and socioeconomic backgrounds in New Zealand (NZ) to gain an understanding of concussion knowledge, awareness of NZ Rugby's (NZR) guidelines and attitudes towards reporting behaviours. Male and female high school rugby players (n= 416) from across NZ were surveyed. The findings indicated that 69% of players had sustained a suspected concussion, and 31% had received a medical diagnosis of concussion. 63% of players indicated they were aware of NZR's guidelines. Maori and Pasifika players were less likely to be aware of the guidelines compared to NZ European, Adjusted OR 0.5, p = 0.03. Guideline awareness was significantly higher for those from high decile schools when compared to low (Unadjusted OR 1.63, p = 0.04); however, when ethnicity and school locations were controlled for this became non-significant (Adjusted OR= 1.3, p=0.37). The coach was the key individual for the provision of concussion information and disclosure of symptoms for players. The findings of this study will inform the development and delivery of NZR's community concussion initiative and how these examined factors influence a high school player's concussion knowledge and reporting behaviour.

Performance Profiling of Female Youth Netball Players.

McKenzie, CR, Whatman, C, and Brughelli, M. Performance profiling of female youth netball players. J Strength Cond Res 34(11): 3275-3283, 2020-The purpose of this study was to investigate the physical performance characteristics of New Zealand secondary school netball players to provide a physical performance profile and determine whether there are differences between playing grade and playing positions for this group. A total of 102 female netball players (mean ± SD: age 13.3 ± 0.50 years, height 166.95 ± 5.72 cm, and body mass 60.94 ± 12.80 kg) participated in this study. Measurements included anthropometry, horizontal and vertical jump performance, balance, core strength, change-of-direction speed, and split sprint times. Magnitude-based inferences were used to determine differences in all measures. Grade 1 players jumped further and higher (effect size [ES] = 0.41-1.37) and ran faster with small to moderate differences. They demonstrated faster change-of-direction speed (ES = -0.73 to -1.31), greater core strength (ES = 0.28-1.17), and a faster time-to-stabilization (ES = -0.69). Grade 2 circle players jumped further (ES = -0.29), compared with noncircle players who jumped higher (ES = 0.35). Noncircle players had faster sprint and change-of-direction speed (ES = -0.33 to -0.55) and measures of balance (ES = -0.47 to 0.55). Grade 1 circle players were found to be faster over 20 m (ES = 0.75). The results of this study showed differences in the physical performance capabilities between youth netball players competing in different grades, as well as differences between playing positions. These findings have provided a physical performance profile of female youth netball players in New Zealand, suggesting that physical performance measures could be used for position-specific training and talent identification and selection.

The Proportion of Lower Limb Running Injuries by Gender, Anatomical Location and Specific Pathology: A Systematic Review.

Running is associated with a higher risk of overuse injury than other forms of aerobic exercise such as walking, swimming and cycling. An accurate description of the proportion of running injuries per anatomical location and where possible, per specific pathology, for both genders is required. The aim of this review was to determine the proportion of lower limb running injuries by anatomical location and by specific pathology in male and female runners (≥800m - ≤ marathon). The preferred reporting items for systematic reviews and meta-analyses guidelines were followed for this review. A literature search was performed with no restriction on publication year in Web of Science, Scopus, Sport-Discus, PubMed, and CINAHL up to July 2017. Retrospective, cross-sectional, prospective and randomised-controlled studies which surveyed injury data in runners were included. 36 studies were included to report the overall proportion of injury per anatomical location. The overall proportion of injury by specific pathology was reported from 11 studies. The knee (28%), ankle-foot (26%) and shank (16%) accounted for the highest proportion of injury in male and female runners, although the proportion of knee injury was greater in women (40% vs. 31%). Relative to women, men had a greater proportion of ankle-foot (26% vs. 19%) and shank (21% vs. 16%) injuries. Patellofemoral pain syndrome (PFPS; 17%), Achilles tendinopathy (AT; 10%) and medial tibial stress syndrome (MTS; 8%) accounted for the highest proportion of specific pathologies recorded overall. There was insufficient data to sub-divide specific pathology between genders. The predominate injury in female runners is to the knee. Male runners have a more even distribution of injury between the knee, shank and ankle-foot complex. There are several methodological issues, which limit the interpretation of epidemiological data in running injury.

Application of a Simple Surveillance Method for Detecting the Prevalence and Impact of Overuse Injuries in Professional Men's Basketball.

The aim of this study was to use the Oslo Sports Trauma Research Center (OSTRC) Overuse Injury Questionnaire to record overuse injuries over a single season for a men's professional basketball team to (a) assess the prevalence and severity of overuse injuries and (b) determine the efficacy of this method in identifying overuse injuries in comparison with the team physiotherapist's detection of these injuries. Thirteen athletes from a men's professional basketball team participated in this study. The self-reported, OSTRC injury questionnaire was used to record overuse conditions of the ankle, knee, and lower back over an entire 24-week season. Standard time-loss injury registration methods were also used to record overuse conditions by the physiotherapist. Overuse injury rates per 1,000 hours of athlete exposure and average weekly prevalence of overuse injuries were calculated using the results of the questionnaire. A total of 183 overuse conditions were identified by the questionnaire, whereas only 28 overuse conditions were identified by the physiotherapist. The team's average weekly prevalence of all overuse conditions was 63% (95% confidence interval [CI]: 60-66), with the highest prevalence of injury affecting the lower back (25.9% [95% CI: 19.7-32.1]). The overuse injury rate per 1,000 hours of athlete exposure was 6.4. The OSTRC overuse injury questionnaire captures many more overuse injuries in basketball than standard time-loss methods. The prevalence of lower back injuries is higher than that previously reported in basketball. This additional method of overuse injury surveillance may more accurately quantify the overuse injury problem in basketball and aid earlier intervention and management of these conditions.

Physical and psychosocial function in residential aged-care elders: effect of Nintendo Wii Sports games.

This mixed-methods, quasi-experimental pilot study examined whether the Nintendo Wii Sports (NWS) active video game (exergame) system could significantly improve the functional ability, physical activity levels, and quality of life of 34 older adults (4 men and 30 women, 83 ± 8 yr) living in 2 residential aged-care (RAC) centers. Change score analyses indicated the intervention group had significantly greater increases in bicep curl muscular endurance, physical activity levels, and psychological quality of life than the control group (p < .05). Analysis of the quotes underlying the 3 themes (feeling silly, feeling good; having fun; and something to look forward to) suggested that intervention group participants developed a sense of empowerment and achievement after some initial reluctance and anxiousness. They felt that the games were fun and provided an avenue for greater socialization. These results add some further support to the utilization of NWS exergames in the RAC context.

Quest for clarity: investigating concussion-related responsibilities across the New Zealand Rugby Community System.

There is a growing concern around concussions in rugby union, at all levels of the game. These concerns highlight the need to better manage and care for players. However, consistency around concussion-related responsibilities of stakeholders across the community rugby system remains challenging. Taking a systems thinking approach, this pragmatic, qualitative descriptive study explored key stakeholder groups within New Zealand's community rugby system's perceptions of their own and others' concussion-related responsibilities. Participants included players from schools and clubs, coaches, parents, team leads and representatives from four provincial unions. A total of 155 participants (67 females and 88 males) were included in the study. Focus groups and individual interviews were conducted. Thematic content analysis was used to analyse data. Thirty concussion-related responsibilities were identified. These responsibilities were contained within four themes: (1) policies and support (responsibilities which influence policy, infrastructure, human or financial resources); (2) rugby culture and general management (responsibilities impacting players' welfare and safety, attitudes and behaviour, including education, injury reporting and communication); (3) individual capabilities (responsibilities demonstrating knowledge and confidence managing concussion, leadership or role/task shifting) and (4) intervention following a suspected concussion (immediate responsibilities as a consequence of a suspected concussion). The need for role clarity was a prominent finding across themes. Additionally, injury management initiatives should prioritise communication between stakeholders and consider task-shifting opportunities for stakeholders with multiple responsibilities. How concussions will realistically be managed in a real-world sports setting and by whom needs to be clearly defined and accepted by each stakeholder group. A 'framework of responsibilities' may act as a starting point for discussion within different individual community rugby contexts on how these responsibilities translate to their context and how these responsibilities can be approached and assigned among available stakeholders.

A systematic video analysis of 21 anterior cruciate ligament injuries in elite netball players during games.

This systematic video analysis of 21 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games, describes the situation, movement pattern and player behaviour, providing insight regarding the injury mechanism. Seventeen of the ACL injuries occurred from jump-landing actions and only two from cutting manoeuvres. A common scenario was identified for 11 players. In this scenario, players were decelerating rapidly after jumping to receive a high pass, utilising a double-footed landing with a wide base of support (WBOS). Deceleration appeared to be applied predominantly via the injured leg with the knee extended and foot planted. Often the players appeared unbalanced on landing leaning too far back. ACL injury risk was possibly exacerbated by the players head turning away from the injured side. A further compressive knee moment may have been placed on the lateral aspect of the knee by bringing the ball from a high position to a low position at the estimated time of injury. Players may benefit from landing technique training programmes that encourage shoulder-width foot landings, with ≥30° knee flexion, a small amount of plantar-flexion and good balance. Incorporating challenges to players balance and ability to cope with perturbations may also be beneficial. Training programmes should include instruction on securing the ball in a stable above pelvis-level position after receiving a pass and bringing their whole body around during landing into the direction of their next pass, rather than simply turning their head to look.

Prevalence of sport specialisation and association with injury history in youth football.

OBJECTIVES: The aims of this study were to determine the prevalence of sport specialisation in youth football, and to investigate the associations of sport specialisation and volume of sport participation with injury history. DESIGN: Cross-sectional questionnaire. SETTING: New Zealand youth football teams. PARTICIPANTS: 414 youth football players aged 10-15 years. MAIN OUTCOME MEASURES: The level of specialisation, average weekly sport participation and free-play volume were recorded. 12-month injury history was captured and grouped by injury type. Associations between level of specialisation and demographic variables were analysed using chi square tests. Logistic regression was used to investigate associations between injury history, level of specialisation, and volume of participation. RESULTS: Participants were classified as high (43%), moderate (38%), or low (19%) specialised (n = 399 complete). High specialisation was more likely in boys, older participants, and those from large schools. Highly specialised participants were more likely to report a history of gradual onset injury than those who were low specialised (n = 340 with complete injury data). Odds of reporting a gradual onset injury also increased with greater weekly and annual sport participation volume. CONCLUSIONS: There is a high prevalence of sport specialisation in youth football, and it is associated with increased incidence of gradual onset injury.

The Value of Sport: Wellbeing Benefits of Sport Participation during Adolescence.

Insight into the unique benefits of sport participation above and beyond those associated with participation in other physical activities among adolescents is limited in Aotearoa New Zealand (NZ). The purpose of this study was to examine the association between wellbeing and organised sport participation among adolescents whilst accounting for demographic characteristics and other recreational physical activity. Demographic characteristics (age, gender, ethnicity, deprivation, (dis)ability status), organized sport, recreational physical activity, and wellbeing were assessed in cohorts of NZ adolescents (11-17 years) between 2017 and 2019. After adjusting for demographics, better wellbeing was associated with participation in any recreational physical activity (OR = 2.49, 95%CI = 1.97-3.13), meeting physical activity recommendations (OR = 1.63, 95%CI = 1.47-1.81), and each additional hour of recreational physical activity (OR = 1.03, 95%CI = 1.02-1.04). After adjusting for demographics and overall recreational physical activity participation, better wellbeing was also associated with participation in any organized sport (OR = 1.66, 95%CI = 1.49-1.86), and each additional hour of organized sport (OR = 1.09, 95%CI = 1.07-1.11). Although participation in recreational physical activity appears to be beneficial for wellbeing, organized sport appears to offer unique additional wellbeing benefits. Positive experiences of organized sport participation may offer additional wellbeing value above and beyond other recreational physical activity types in young people who are active.

"Balance Is Better": The Wellbeing Benefits of Participating in a Breadth of Sports across a Variety of Settings during Adolescence.

The purpose of this study was to examine how wellbeing is associated with the setting in which sport participation takes place and the breadth of sport participation. Demographic characteristics (age, gender, ethnicity, deprivation, (dis)ability status), recreational physical activity, and wellbeing were assessed in cohorts of adolescents (11-17 years) between 2017 and 2019 in Aotearoa, New Zealand. Better wellbeing was associated with participation in any sport vs. none (OR = 1.57, 95% CI = 1.30-1.90). Better wellbeing was also associated with participating in any coached sport training (OR = 1.48, 95% CI = 1.33-1.66), competitive sport (OR = 1.33, 95% CI = 1.18-1.49), social sport (OR = 1.33, 95% CI = 1.18-1.49), and uncoached sport training (OR = 1.16, 95% CI = 1.03-1.31) compared to non-participation in the given setting. Wellbeing was not associated with participation in physical education or solo sport. Participating in sport in three to five different settings (3 settings: OR = 1.21, 95% CI = 1.01-1.44; 4 settings: OR = 1.33, 95% CI = 1.09-1.62; 5 settings: OR = 1.37, 95% CI = 1.07-1.75) or sports (3 sports: OR = 1.25, 95% CI = 1.04-1.51; 4 sports: OR = 1.31, 95% CI = 1.06-1.61; 5 sports: OR = 1.33, 95% CI = 1.05-1.69) was associated with better wellbeing compared to participation in a single setting or sport, respectively. A balanced approach to participating across a variety of sport settings and sports that are facilitated by quality coaches may offer the largest additional wellbeing value.

Visual rating of movement quality in individuals with and without a history of intra-articular knee injury.

Objective: To investigate the use of visually rated movement quality in a group including those with a history of intra-articular knee injury.Design: Historical cohort study.Setting: Laboratory.Participants: A total of 115 youth and young adults (62 previously injured).Main outcome measures: Inter-rater agreement for ratings of movement quality during single limb squat and vertical drop jump (VDJ) were assessed. Odds ratios were calculated to determine if the history of knee injury was associated with greater odds of poor movement quality. The difference in knee:ankle separation ratio between the injured and uninjured groups was compared.Results: Rater agreement was moderate to excellent (κ = 0.55 to 0.93). Comparing the injured and uninjured limb in previously injured participants or injured participants to matched uninjured controls, there was no significant difference in the proportion of good versus poor movement ratings (diff = 0% to 10%; p ≥ 0.23). Prior history of knee injury did not increase the odds of poor movement quality during the VDJ (OR 0.91; 95% CI 0.41 to 2.03) or single leg squat (OR 1.04; 95% CI 0.38 to 2.85) and there was no significant difference in the knee:ankle separation ratios (mean diff -0.03; p = 0.30).Conclusion: Visual rating of movement in individuals with and without a history of knee injury is reliable. A history of knee injury does not increase the likelihood of poor visually rated movement quality.

Short and long versions of a 12-week netball specific neuromuscular warm-up improves landing technique in youth netballers.

OBJECTIVE: To investigate the efficacy of two 'NetballSmart', netball specific warm-ups in improving landing technique measures in New Zealand secondary school netball players. DESIGN: Multi-site cluster experimental trial. PARTICIPANTS: 77 youth participants, mean ± SD age = 15.8 ± 0.9 were recruited from secondary school netball teams. SETTING: 12 teams from 6 schools performed either the NetballSmart Dynamic Warm-up (NSDW) (n = 37); or Power warm-up (PWU) (n = 40), three times a week for 12 weeks. All players within a school (2 teams) were assigned the same warm-up, avoiding treatment contamination. MAIN OUTCOME MEASURES: A series of unilateral and bilateral drop vertical jumps on to a portable force plate were completed by all participants. Measures included peak vertical ground reaction force (GRF) for single-leg and bilateral landings; frontal plane projection angle (FPPA) for right and left single-leg landings and Landing error scoring system (LESS) for bilateral landings. Paired t-tests were used to assess mean differences pre and post the warm-up. Generalised linear mixed effects models were developed to evaluate the effects between the NSDW and PWU groups. RESULTS: Significant improvements were found in all the landing technique outcome measures for both warm-up groups (ES Range- GRF = -0.6 to -1.1; FPPA = 0.8 to 1.2; LESS = -1.6 to-3.2; p < 0.05). Results of mixed effects models revealed that there was only a significantly greater improvement in LESS for the PWU group (ß = -0.30, p = 0.001). CONCLUSION: Results show both warm-ups can improve landing technique measures in youth secondary school netball players. It is recommended that coaches should consider implementing one of the two warm-ups in their netball programmes. Their choice of warm-up will likely be dependent on their environment and time demands.

Sport Specialization, Physical Performance and Injury History in Canadian Junior High School Students.

BACKGROUND: Youth sports participation is encouraged for proposed physical and psychological benefits. However early sport specialization and the potentially negative consequences may be a cause for concern. PURPOSE: To describe sport specialization in Canadian youth and investigate associations with previous injury and physical performance. STUDY DESIGN: Cross-sectional study. METHODS: Junior high school students (grades 7-9, ages 11-16) were invited to participate. All participants completed a questionnaire capturing specialization level (low, moderate, high; based on year-round training, exclusion of other sports, and single-sport training) and injury history in the previous 12-months. Additionally, all participants completed physical performance measures including vertical jump (cm), predicted VO2max (mL/kg/min), single-leg balance (secs) and Y-Balance composite score (%). Logistic regression examined the association between school grade, school size, sex and sport specialization (Objective 1) and the association between sport specialization and injury history (Objective 2). Multivariable linear regression analyses (4) assessed associations between sport specialization category and physical performance measures (Objective 3). RESULTS: Two hundred and thirty-eight students participated in the study. Eighteen percent of participants reported high specialization, with no significant associations between sex, grade or school size and specialization category. There was no significant difference in the odds of sustaining previous injury between participants reporting moderate (odds ratio [OR]=1.94, 95% CI 0.86-4.35) or high (OR=2.21, 95% CI 0.43-11.37) compared to low specialization. There were no significant differences in vertical jump height (mean diff [MD] = -0.4 to 2.1cm), predicted VO2max (MD = 2.2 to 3.1mL/kg/min), single leg balance (MD = 0.5 to 1.9sec) or Y-balance (MD = 0.6 to 7.0%) between sport specialization categories. CONCLUSIONS: Sport specialization exists in Canadian junior high schools but may be less common than previously reported and it was not associated with sex, grade, or school size. Level of specialization was not associated with history of injury nor a range of physical performance measures. LEVEL OF EVIDENCE: Level 3.