Stephanie M. Trigsted

Prevalence of Sport Specialization in High School Athletics A 1-Year Observational Study

Background: The prevalence of sport specialization in high school athletes is unknown. This information is needed to determine the scope of this issue in an active population. Purpose: To determine the prevalence of sport specialization in high school athletes and to determine if specialization is influenced by classification method, year in school, sex, and school size. A secondary purpose was to determine if highly specialized athletes would be more likely to report a history of lower extremity injuries. Study Design: Cross-sectional study; Level of evidence, 3. Methods: High school athletes between the ages of 13 and 18 years from 2 local high schools completed both a sport specialization survey and an injury history survey. Athletes were classified into low, moderate, or high specialization groups using a recently developed 3-point system and were also classified using a self-classification method. Results: A total of 302 athletes completed the surveys and were classified as low specialization (n = 105, 34.8%), moderate specialization (n = 87, 28.8%), or high specialization (n = 110, 36.4%). Athletes from the small school were more likely to be classified in the low specialization group (low, 43%; moderate, 32%; high, 25%) compared with those from the large school (low, 26%; moderate, 26%; high, 48%) (P < .001). Athletes in the high specialization group were more likely to report a history of overuse knee injuries (n = 18) compared with moderate (n = 8) or low specialization (n = 7) athletes (P = .048). Athletes who trained in one sport for more than 8 months out of the year were more likely to report a history of knee injuries (odds ratio [OR], 2.32; 95% CI, 1.22-4.44; P = .009), overuse knee injuries (OR, 2.93; 95% CI, 1.16-7.36; P = .018), and hip injuries (OR, 2.74; 95% CI, 1.09-6.86; P = .026). Using the self-classification method, more participants self-classified as multisport (n = 213, 70.5%) than single sport (n = 89, 29.5%). Athletes from the small school were more likely to classify themselves as multisport (n = 128, 86%) (P < .001) than those from the large school (n = 85, 56%). There were no differences in the history of hip, knee, or ankle injuries between athletes who self-classified as single sport (hip: n = 10, 3%; knee: n = 19, 6%; ankle: n = 35, 12%) versus those who self-classified as multisport (hip: n = 45, 8%; knee: n = 23, 15%; ankle: n = 98, 33%) (P > .370). Conclusion: Classification method and school size influenced the prevalence of specialization in high school athletes. Highly specialized athletes were more likely to report a history of overuse knee or hip injuries. Participating in a single sport for more than 8 months per year appeared to be an important factor in the increased injury risk observed in highly specialized athletes.

The Association of Sport Specialization and Training Volume With Injury History in Youth Athletes

Background: Recommendations exist to encourage safe youth participation in sport. These recommendations include not specializing in 1 sport, limiting participation to less than 8 months per year, and limiting participation to fewer hours per week than a child’s age. However, limited evidence exists to support or refute these recommendations. Hypothesis: High levels of specialization will be associated with a history of injuries and especially overuse injuries, independent of age, sex, or weekly sport training hours. Athletes who exceed current sport volume recommendations will be more likely to have a history of injuries and overuse injuries. Study Design: Case-control study; Level of evidence, 3. Methods: Youth athletes (n = 2011; 989 female and 1022 male; 12-18 years of age) completed a questionnaire regarding their specialization status, yearly and weekly sport participation volume, and injury history. Specialization was classified as low, moderate, or high using a previously utilized 3-point scale. Athletes were classified into groups based on either meeting or exceeding current volume recommendations (months per year and hours per week). Odds ratios (ORs) and 95% CIs were calculated to investigate associations of specialization and volume of participation with a history of sport-related injuries in the past year (P ≤ .05). Results: Highly specialized athletes were more likely to report a previous injury of any kind (P < .001; OR, 1.59; 95% CI, 1.26-2.02) or an overuse injury (P = .011; OR, 1.45; 95% CI, 1.07-1.99) in the previous year compared with athletes in the low specialization group. Athletes who played their primary sport more than 8 months of the year were more likely to report an upper extremity overuse injury (P = .04; OR, 1.68; 95% CI, 1.06-2.80) or a lower extremity overuse injury (P = .001; OR, 1.66; 95% CI, 1.22-2.30). Athletes who participated in their primary sport for more hours per week than their age (ie, a 16-year-old athlete who participated in his or her primary sport for more than 16 h/wk) were more likely to report an injury of any type (P = .001; OR, 1.34; 95% CI, 1.12-1.61) in the previous year. Conclusion: High levels of specialization were associated with a history of injuries, independent of age, sex, and weekly organized sport volume. Athletes who exceeded volume recommendations were more likely to have a history of overuse injuries. Clinical Relevance: Parents and youth athletes should be aware of the risks of specialization and excessive sport volume to maximize safe sport participation.

High School Sport Specialization Patterns of Current Division I Athletes

Background: Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. Hypothesis: College athletes will display increased rates of specialization as they progress through their high school careers. Study Design: Descriptive epidemiological study. Level of Evidence: Level 4. Methods: Three hundred forty-three athletes (115 female) representing 9 sports from a Midwest Division I University completed a previously utilized sport specialization questionnaire regarding sport participation patterns for each grade of high school. McNemar and chi-square tests were used to investigate associations of grade, sport, and sex with prevalence of sport specialization category (low, moderate, high) (a priori P ≤ 0.05). Results: Specialization increased throughout high school, with 16.9% (n = 58) and 41.1% (n = 141) of athletes highly specialized in 9th and 12th grades, respectively. Football athletes were less likely to be highly specialized than nonfootball athletes for each year of high school (P < 0.001). There was no difference in degree of specialization between sexes at any grade level (P > 0.23). Conclusion: The majority of Division I athletes were not classified as highly specialized throughout high school, but the prevalence of high specialization increased as athletes progressed through high school. Nonfootball athletes were more likely to be highly specialized than football athletes at each grade level. Clinical Relevance: Most athletes who are recruited to participate in collegiate athletics will eventually specialize in their sport, but it does not appear that early specialization is necessary to become a Division I athlete. Athletes should be counseled regarding safe participation in sport during high school to minimize injury and maximize performance.

Landing mechanics during single hop for distance in females following anterior cruciate ligament reconstruction compared to healthy controls.

PurposeTo determine possible differences in single-hop kinematics and kinetics in females with anterior cruciate ligament reconstruction compared to healthy controls. A second purpose was to make comparisons between the healthy and reconstructed limbs.MethodsSubjects were grouped based on surgical status (33 ACLR patients and 31 healthy controls). 3D motion capture synchronized with force plates was used to capture the landing phase of three successful trials of single hop for distance during a single data collection session. Peak values during the loading phase were analysed. Subjects additionally completed three successful trials of the triple hop for distance Tegner activity scale and International Knee Document Committee 2000 (IKDC).ResultsControls demonstrated greater peak knee flexion and greater internal knee extension moment and hip extension moment than ACLR subjects. Within the ACLR group, the healthy limb exhibited greater peak knee flexion, hip flexion, hip extension moment, single hop and triple hops for distance and normalized quadriceps strength.ConclusionPatients who undergo anterior cruciate ligament reconstruction land in a more extended posture when compared to healthy controls and compared to their healthy limb.Level of evidenceIII.

A Prospective Study on the Effect of Sport Specialization on Lower Extremity Injury Rates in High School Athletes.

Background: Sport specialization is associated with an increased risk of musculoskeletal lower extremity injuries (LEIs) in adolescent athletes presenting in clinical settings. However, sport specialization and the incidence of LEIs have not been investigated prospectively in a large population of adolescent athletes. Purpose: To determine if sport specialization was associated with an increased risk of LEIs in high school athletes. Study Design: Cohort study; Level of evidence, 2. Methods: Participants (interscholastic athletes in grades 9-12) were recruited from 29 Wisconsin high schools during the 2015-2016 school year. Participants completed a questionnaire identifying their sport participation and history of LEIs. Sport specialization of low, moderate, or high was determined using a previously published 3-point scale. Athletic trainers reported all LEIs that occurred during the school year. Analyses included group proportions, odds ratios (ORs) and 95% CIs, and days lost due to injury (median and interquartile range [IQR]). Multivariate Cox proportional hazard ratios (HRs) with 95% CIs were calculated to investigate the association between the incidence of LEIs and sport specialization level. Results: A total of 1544 participants (50.5% female; mean age, 16.1 ± 1.1 years) enrolled in the study, competed in 2843 athletic seasons, and participated in 167,349 athlete-exposures. Sport specialization was classified as low (59.5%), moderate (27.1%), or high (13.4%). Two hundred thirty-five participants (15.2%) sustained a total of 276 LEIs that caused them to miss a median of 7.0 days (IQR, 2.0-22.8). Injuries occurred most often to the ankle (34.4%), knee (25.0%), and upper leg (12.7%) and included ligament sprains (40.9%), muscle/tendon strains (25.4%), and tendinitis/tenosynovitis (19.6%). The incidence of LEIs for moderate participants was higher than for low participants (HR, 1.51 [95% CI, 1.04-2.20]; P = .03). The incidence of LEIs for high participants was higher than for low participants (HR, 1.85 [95% CI, 1.12-3.06]; P = .02). Conclusion: Athletes with moderate or high sport specialization were more likely to sustain an LEI than athletes with low specialization. Sports medicine providers need to educate coaches, parents, and interscholastic athletes regarding the increased risk of LEIs for athletes who specialize in a single sport.

Association of Competition Volume, Club Sports, and Sport Specialization With Sex and Lower Extremity Injury History in High School Athletes

Background: High school athletes are increasingly encouraged to participate in 1 sport year-round to increase their sport skills. However, no study has examined the association of competition volume, club sport participation, and sport specialization with sex and lower extremity injury (LEI) in a large sample of high school athletes. Hypothesis: Increased competition volume, participating on a club team outside of school sports, and high levels of specialization will all be associated with a history of LEI. Girls will be more likely to engage in higher competition volume, participate on a club team, and be classified as highly specialized. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: High school athletes completed a questionnaire prior to the start of their competitive season regarding their sport participation and previous injury history. Multivariable logistic regression analyses were used to investigate associations of competition volume, club sport participation, and sport specialization with history of LEI, adjusting for sex. Results: A cohort of 1544 high school athletes (780 girls; grades 9-12) from 29 high schools completed the questionnaire. Girls were more likely to participate at high competition volume (23.2% vs 11.0%, χ2 = 84.7, P < 0.001), participate on a club team (61.2% vs 37.2%, χ2 = 88.3, P < 0.001), and be highly specialized (16.4% vs 10.4%, χ2 = 19.7, P < 0.001). Athletes with high competition volume, who participated in a club sport, or who were highly specialized had greater odds of reporting a previous LEI than those with low competition volume (odds ratio [OR], 2.08; 95% CI, 1.55-2.80; P < 0.001), no club sport participation (OR, 1.50; 95% CI, 1.20-1.88; P < 0.001), or low specialization (OR, 2.58; 95% CI, 1.88-3.54; P < 0.001), even after adjusting for sex. Conclusion: Participating in high sport volume, on a club team, or being highly specialized was associated with history of LEI. Girls were more likely to participate at high volumes, be active on club teams, or be highly specialized, potentially placing them at increased risk of injury. Clinical Relevance: Youth athletes, parents, and clinicians should be aware of the potential risks of intense, year-round participation in organized sports.

Hip Strength in Patients with Quadriceps Strength Deficits after ACL Reconstruction.

PURPOSE Quadriceps strength deficits persist for years after anterior cruciate ligament (ACL) reconstruction, and patients with these deficits often shift torque demands away from the knee extensors to the hip during functional tasks. However, it is not clear how quadriceps strength deficits may affect hip strength. Therefore, the purpose of this study was to investigate differences in lower extremity strength in individuals with ACL reconstruction with differing levels of quadriceps strength asymmetry. METHODS Isometric strength was recorded bilaterally in 135 participants (73 control and 62 with unilateral ACL reconstruction, time from surgery = 30.9 ± 17.6 months) from the knee extensors and flexors, hip extensors and abductors, and hip internal and external rotator muscle groups. Symmetry indices (limb symmetry index (LSI)) were created based on quadriceps strength, and subjects with ACL reconstruction were subdivided (high quadriceps (LSI ≥ 90%), n = 37; low quadriceps (LSI < 85%), n = 18). Individual group (control vs high quadriceps vs low quadriceps) by limb (reconstructed/nondominant vs healthy/dominant) repeated-measures ANOVA was used to compare strength (%BW) for each of the six joint motions of interest (knee extensors/flexors, hip abductors/extensors/external, and internal rotators) while controlling for time from surgery. RESULTS An interaction was observed for quadriceps strength (P < 0.001), and the reconstructed limb in the low quadriceps group was weaker than all other limbs. A main effect for group was observed with the low quadriceps group having greater hip extension (P = 0.007) strength in both limbs compared with the other groups. Knee flexion strength was weaker in the reconstructed limb of the high quadriceps group (P = 0.047) compared with all other groups and limbs. CONCLUSIONS Individuals with ACL reconstruction and involved limb quadriceps weakness have greater hip extension strength in both limbs compared with patients with bilateral strength symmetry and controls.

Objectively measured physical activity in patients after anterior cruciate ligament reconstruction

Background: Returning to a healthy level of physical activity is among the most commonly discussed clinical goals for patients recovering from anterior cruciate ligament reconstruction (ACLR). However, physical activity has not been objectively measured in this population. Purpose: To investigate differences in the mean time (min/d) spent in moderate-to-vigorous physical activity (MVPA) as well as the daily step count (steps/d) between patients who underwent ACLR and matched controls. A second purpose was to investigate relationships between MVPA and objective assessments of the daily step count and Tegner and Marx activity scales. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Physical activity was assessed using ActiGraph accelerometers in 33 participants with a history of primary unilateral or bilateral ACLR (mean time from surgery, 27.8 ± 17.5 months; range, 6-67 months) as well as in 33 healthy controls (matched on age, sex, and activity level). Participants wore the accelerometer for 7 days and completed the International Knee Documentation Committee subjective form and the Tegner and Marx activity scales. Independent t tests were used to determine differences in each dependent variable per group. Results: Patients who underwent ACLR spent less time in MVPA (ACLR: 79.37 ± 23.95 min/d; control: 93.12 ± 23.94 min/d; P = .02) and had a lower daily step count (ACLR: 8158 ± 2780 steps/d; control: 9769 ± 2785 steps/d; P = .02) compared with healthy matched controls. However, the Marx (ACLR median: 11.0 [interquartile range (IQR), 7-14]; control median: 12.0 [IQR, 8-13]; P = .85) and Tegner (ACLR median: 6.0 [IQR, 5-8]; control median: 7.0 [IQR, 6-8]; P = .12) scores did not differ between the groups, and no relationships were observed between objectively measured physical activity and scale measures (P > .05), except for a moderate relationship between the Tegner score and daily step count in the ACLR group (r = 0.36, P = .04). Only 24% of patients who underwent ACLR met the guideline of 10,000 steps per day compared with 42% of controls. Conclusion: Patients who underwent ACLR spent less time in MVPA and had a lower daily step count compared with highly matched controls (age, sex, and activity level) with no history of knee injuries. This was true despite being similar in activity levels, which brings into question the utility of the Tegner and Marx activity scales.

The Effects of Specialization and Sex on Anterior Y-Balance Performance in High School Athletes.

Background: Sport specialization and movement asymmetry have been separately discussed as potential risk factors for lower extremity injury. Early specialization may lead to the development of movement asymmetries that can predispose an athlete to injury, but this has not been thoroughly examined. Hypothesis: Athletes rated as specialized would exhibit greater between-limb anterior reach asymmetry and decreased anterior reach distance on the Y-balance test (YBT) as compared with nonspecialized high school athletes, and these differences would not be dependent on sex. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: Two hundred ninety-five athletes (117 male, 178 female; mean age, 15.6 ± 1.2 years) from 2 local high schools participating in basketball, soccer, volleyball, and tennis responded to a questionnaire regarding sport specialization status and performed trials of the YBT during preseason testing. Specialization was categorized according to 3 previously utilized specialization classification methods (single/multisport, 3-point scale, and 6-point scale), and interactions between specialization and sex with Y-balance performance were calculated using 2-way analyses of variance. Results: Single-sport male athletes displayed greater anterior reach asymmetry than other interaction groups. A consistent main effect was observed for sex, with men displaying greater anterior asymmetry and decreased anterior reach distance than women. However, the interaction effects of specialization and sex on anterior Y-balance performance varied based on the classification method used. Conclusion: Single-sport male athletes displayed greater anterior reach asymmetry on the YBT than multisport and female athletes. Specialization classification method is important because the 6- and 3-point scales may not accurately identify balance abnormalities. Male athletes performed worse than female athletes on both of the Y-balance tasks. Clinical Relevance: Clinicians should be aware that single-sport male athletes may display deficits in dynamic balance, potentially increasing their risk of injury.

Sport Specialization Characteristics Between Rural and Suburban High School Athletes

Background: Sport specialization has been associated with overuse injuries and is more common in larger high schools, which are often located in more urban/suburban settings. However, sport participation characteristics have not been compared between suburban and rural high schools. Purpose/Hypothesis: The purpose of this study was to examine the differences in sport participation characteristics between athletes at suburban and rural high schools. It was hypothesized that suburban high school students would be more likely to be highly specialized, participate in more athletic competitions per year, and play in a league outside of school. We also hypothesized that suburban high school students would start playing their primary sport at a younger age, would have participated in their primary sport for longer, and would play more months per year and hours per week. Study Design: Cross-sectional study. Methods: High school athletes from 4 high schools (2 suburban and 2 rural) participated in this study (N = 354 [222 females]; mean age, 15.7 ± 1.2 years). Athletes were on a school-sponsored athletic team in 1 of 4 sports (volleyball, tennis, basketball, soccer). The suburban schools (study enrollment, n = 226) had total school enrollments of 2271 and 622 students, while the rural schools (study enrollment, n = 128) had total school enrollments of 443 and 297. Participants completed a questionnaire prior to the start of their high school sport season. The questionnaire consisted of demographic information, a sport specialization scale, and sport participation information. Primary sport competition volume in the previous 12 months was classified as high (>60 primary sport competitions), moderate (30-60), or low (<30). Sport specialization status was classified via a 3-point scale as low, moderate, or high. Results: As compared with athletes at rural schools, athletes at suburban schools started playing their primary sport at a younger age (suburban, 7.8 ± 2.9 years; rural, 9.7 ± 3.2 years; P < .001) and participated for more years (suburban, 7.9 ± 3.1 years; rural, 6.1 ± 3.3 years; P < .001), more months per year (suburban, 7.6 ± 3.6 months; rural, 5.6 ± 2.8 months; P < .001), and more hours per week (suburban, 15.2 ± 5.1 hours; rural, 12.9 ± 3.3 hours; P < .001). Athletes at suburban schools were more likely than rural athletes to be classified as highly specialized (χ2 = 52.5, P < .001), participate in more competitions (χ2 = 16.5, P < .001), play in a league outside of school (χ2 = 18.4, P < .001), and train in their primary sport for >8 months per year (χ2 = 27.8, P < .001) and >16 hours per week (χ2 = 15.0, P < .001). Conclusion: High school athletes at suburban schools are more likely to exhibit sport participation patterns that are associated with increased risk of overuse injury. These include being classified as highly specialized, playing their primary sport >8 months per year and >16 hours per week, engaging in a high competition volume, and participating in a sport league (eg, club) outside of school. Efforts aimed at safe sport participation should target these groups, as they seem more likely to violate safe sport recommendations.