Sports Health: A Multidisciplinary Approach

Current research on concussion incidence in youth athletes (age <18 years) is small and limited by variability in injury reporting and diagnostic methodology.

Concussion injuries commonly occur in high school sports programs. The likelihood of concussion among student-athletes (aged 13-18 years) depends on the sport they are participating in as well as the sex of the athlete.

Descriptive epidemiology study.

Level 4.

A retrospective analysis of all Hawaii high school athletes aged 13 to 18 years participating in 14 sports from 2011 through 2017 was performed as part of a statewide standardized concussion assessment and management program.

A total of 5993 concussions were identified among 92,966 athletes. The overall concussion rate was 0.96 (95% CI, 0.94-0.99). Girls’ judo had the highest concussion rate (1.92; 95% CI, 1.68-2.17) followed by football (1.60; 95% CI, 1.53-1.66). The concussion rate for boys (1.0; 95% CI, 0.97-1.03) was higher than that for girls (0.91; 95% CI, 0.87-0.95); however, in 4 of the 5 sports in which both girls and boys participated, girls had a higher rate of concussion injury.

The likelihood of concussion among student-athletes aged 13 to 18 years may be higher than previously thought and varies depending on sport and sex.

Epidemiologic data on concussion injury in children and adolescents are useful in accurately determining the relative risks of high school sports participation and may be valuable in determining the appropriate allocation of health care and scholastic resources for student-athletes, as well as the impact of rule and training modifications designed to improve participant safety.

The relationships between sport specialization, physical activity, sleep, and illness in younger athletes are unknown. Therefore, the purpose of this study was to evaluate the independent effects of sport specialization, sleep, and physical activity on illness in middle school athletes.

Decreased sleep, decreased physical activity, and higher levels of sport specialization will be associated with an increased risk of illness among middle school athletes.

Prospective cohort study.

Level 4.

Parents of middle school–aged children reported baseline sport specialization (low, moderate, or high) as well as sleep duration, physical activity, and illnesses every week throughout the academic year. A mixed-effects logistic regression model was used to assess the association between illness and specialization while accounting for sleep and physical activity for the prior week as fixed effects and each individual as a random effect.

A total of 233 children (mean age, 12.1 ± 1.2 years; 61% male) participated, of whom 41%, 25%, and 34% were categorized as low, moderate, and high specialization, respectively. The proportion of individuals who experienced illness did not differ by specialization level (low, 76%; moderate, 70%; high, 59%; P = 0.064). In the multivariable model, the odds of illness compared with the low specialization group was not significantly different for moderate (odds ratio [OR], 0.93; 95% CI, 0.70-1.23; P = 0.61) or high specialization (OR, 0.76; 95% CI, 0.56-1.03; P = 0.073). A decreased risk of illness was associated with greater prior week sleep (OR, 0.79; 95% CI, 0.69-0.91; P < 0.001) and physical activity (OR, 0.94; 95% CI, 0.92-0.96; P < 0.001).

Sport specialization is not associated with an increased risk of illness among middle school athletes, while increased sleep duration and physical activity appear to reduce the risk of illness.

Interventions to promote physical activity and improve sleep may reduce the risk of illness in early adolescent athletes.

The long-term effect of sport-related concussion on mood in adolescent athletes is largely unknown.

Longitudinal measures of depression will worsen acutely after sport-related concussion and improve with concussion symptom resolution.

Prospective cohort study.

Level 3.

A population-based sample of 2160 high school athletes from 31 urban, suburban, and rural high schools completed preseason baseline concussion symptom evaluation and Patient Health Questionnaire–9 (PHQ-9) assessments over 2 years. Athletic trainers recorded onset of sport-related concussion, and concussed athletes completed the PHQ-9 assessment within 24 to 72 hours, 7 days, date of return to sport, 3 months, 6 months, and 12 months after sport-related concussion. Scores at each time point were compared to baseline with mixed-effects models and repeated-measures analysis of variance. Sex-based differences were assessed using mixed-effect models.

Of the 2160 athletes enrolled in the study, 125 (5.8%; 80 males, 45 females) sustained a sport-related concussion. PHQ-9 scores worsened from baseline at 24 to 72 hours (+1.05; 95% CI, 0.26-1.84; P = 0.003) and 7 days (+0.91; 95% CI, 0.23-1.60; P = 0.006). However, PHQ-9 scores improved from baseline to date of return to sport (−1.38; 95% CI, −2.20 to −0.55; P < 0.001), 3 months (−1.08; 95% CI, −1.88 to −0.28; P = 0.003), 6 months (−1.19; 95% CI, −2.04 to −0.34; P = 0.001), and 12 months after sport-related concussion (−0.76; 95% CI, −1.43 to −0.08; P = 0.028). Female athletes reported more severe concussion symptoms 24 to 72 hours after sport-related concussion compared with male athletes (female, 20.5 [interquartile range (IQR), 10.0-36.2]; male, 9.0 [IQR, 4.0-19.5]; P = 0.003). Neither PHQ-9 scores nor change in PHQ-9 scores differed between male and female athletes at any time point.

Sport-related concussion did not worsen longitudinal measures of depressed mood in this cohort of high school athletes.

Emotional symptoms are common after sport-related concussion, but typically resolve by return to sport.

Plyometric training has been shown to be beneficial in adolescent overhead athletes. However, existing research on the effects of plyometrics on sport performance has been limited.

To systematically review the current literature to investigate whether plyometric training intervention improves upper- and lower-body sport performance.

Two electronic databases (MEDLINE and Web of Science) were searched using specific Medical Subject Headings (MeSH) terms up to February 2019, and hand-searching was performed by looking to relevant studies that were cited in other studies.

A total of 932 items were identified and were further assessed for the eligibility in the systematic review. For a study to be eligible, each of the following inclusion criteria had to be met: (1) participants were aged 13 to 18 years and selected from a sports or athletic population and the study (2) involved the evaluation of a plyometric training intervention with an aim to improve sports performance; (3) must have included a control intervention and/or control group; (4) included a quantitative objective measure of sport performance variables concerning throwing, jumping, running, and sprinting; and (5) was published in English.

Systematic review.

Level 3.

A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria.

A total of 14 studies were included in this review. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that plyometric training intervention improves throwing and jumping performances. There is also preliminary evidence that plyometric training intervention improves sprint performance.

The current evidence suggests that sport performance consisting of throwing capacity, jumping ability, and sprint performance significantly improved due to plyometric training interventions in adolescent overhead athletes.

Functional bracing is often used as an adjunct to nonoperative treatment of anterior shoulder instability, but no study has evaluated the effectiveness of in-season bracing. The purpose of this study was to examine successful return to play in a nonoperative cohort of adolescent athletes with in-season shoulder instability and compare those athletes treated with bracing to those who were not.

The use of functional bracing will improve success rates in a cohort of athletes treated nonoperatively for in-season shoulder instability.

Cohort study.

Level 3.

A total of 97 athletes with anterior shoulder instability were followed for a minimum of 1 year. The mean age was 15.8 ± 1.4 years (range, 12.0-18.0 years). All athletes were treated with initial nonoperative management. Twenty athletes (21%) were also treated with bracing while 77 (79%) were not. The athlete completing the current season and 1 subsequent season without surgery or time lost from shoulder injury was defined as a successful outcome.

There was no statistical difference in nonoperative success rates between the braced and nonbraced athletes (P = 0.33). Braced athletes (n = 20) returned to play 80% of the time, while nonbraced athletes (n = 77) returned at a rate of 88%. Of the braced athletes, 85% were football players (n = 17). A football-only comparison demonstrated no difference between braced failures (26%) and nonbraced failures (16%) (P = 0.47).

This is the first study to evaluate the utility of functional bracing in returning an athlete to sport and completing a full subsequent season without surgery or time loss due to injury of the shoulder. In adolescent athletes with shoulder instability treated nonoperatively, functional bracing did not result in increased success rates when compared with no bracing.

The data from this study indicate that functional bracing may not improve success rates for athletes with shoulder instability.

Patellofemoral pain (PFP) syndrome is closely associated with muscle tightness. However, studies regarding the effects of stretching exercises on PFP patients with inflexible hamstrings are scarce. The aim of the study was to compare the effects between static and dynamic hamstring stretching in patients with PFP who have inflexible hamstrings.

Compared with static hamstring stretching, dynamic hamstring stretching will improve the parameters of hamstring flexibility, knee muscle strength, muscle activation time, and clinical outcomes in this patient population.

Prospective randomized controlled trial.

Level 2.

A total of 46 patients (25, static stretching; 21, dynamic stretching) participated. Hamstring flexibility was assessed according to the popliteal angle during active knee extension. Muscle strength and muscle activation time were measured using an isokinetic device. Clinical outcomes were evaluated using the visual analog scale (VAS) for pain and the anterior knee pain scale (AKPS).

There were no differences in hamstring flexibility and knee muscle strength of the affected knees between the groups (P > 0.05). Significantly improved muscle activation time and clinical outcomes of the affected knees were observed in the dynamic stretching group compared with the static stretching group (all Ps < 0.01 for hamstring, quadriceps, VAS, and AKPS).

In patients with PFP who have inflexible hamstrings, dynamic hamstring stretching with strengthening exercises was superior for improving muscle activation time and clinical outcomes compared with static hamstring stretching with strengthening exercises.

Clinicians and therapists could implement dynamic hamstring stretching to improve function and reduce pain in patients with PFP who have inflexible hamstrings.

Evidence concerning a systematic, comprehensive injury risk assessment in the elite swimming population is scarce.

To evaluate the quality of current literature regarding clinical assessment techniques used to evaluate the presence and/or development of pain/injury in elite swimmers and to categorize objective clinical assessment tools into relevant predictors (constructs) that should consistently be evaluated in injury risk screens of elite swimmers.

PubMed, Embase, Scopus, CINAHL, SPORTDiscus, PEDro, and the Cochrane Library Reviews were searched through September 2018.

Studies were included for review if they assessed a correlation between clinic-based objective measures and the presence and/or development of acute or chronic pain/injury in elite swimmers. All body regions were included. Elite swimmers were defined as National Collegiate Athletic Association, collegiate, and junior-, senior-, or national-level swimmers. Only cohort and cross-sectional studies were included (both prospective and retrospective); randomized controlled trials, expert opinion, and case reports were excluded, along with studies that focused on interventions, performance, or specific swim-stroke equipment or technology.

Systematic review and qualitative analysis.

Level 3.

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were utilized at each phase of review by 2 reviewers; a third reviewer was utilized for tie breaking purposes. Qualitative analysis was performed using the Methodological Items for Non-Randomized Studies (MINORS) assessment tool.

A total of 21 studies assessed the presence and/or development of injury/pain in 3 different body regions: upper extremity, lower extremity, and spine. Calculated average MINORS scores for comparative (n = 17) and noncomparative (n = 4) studies were 18.1 of 24 and 10.5 of 16, respectively. Modifiable, objectively measurable injury risk factors in elite swimmers were categorized into 4 constructs: (1) strength/endurance, (2) mobility, (3) static/dynamic posture, and (4) patient-report regardless of body region.

Limited evidence exists to draw specific correlations between identified clinical objective measures and the development of pain and/or injury in elite swimmers.

Malnutrition is well-studied in various aspects of the orthopaedic literature, most commonly in relation to arthroplasty, spine surgery, and trauma. However, the management of nutritional deficiencies is commonly overlooked among orthopaedic sports medicine providers. The purpose of this article is to analyze the available sports medicine literature to review the associations between malnutrition and the management of orthopaedic sports medicine patients from a treatment and performance standpoint.

PubMed was searched for relevant articles published from 1979 to 2019.

Clinical review.

Level 4.

Few studies exist on the implications of macronutrient deficiencies specific to orthopaedic sports medicine procedures. Interestingly, micronutrient disorders—namely, hypovitaminosis D and iron deficiency—have been well studied and may lead to worse postoperative outcomes, injury rates, and athletic performance. Nutritional supplementation to correct such deficiencies has been shown to mitigate these effects, though further study is required.

Nutritional deficiencies are highly prevalent in orthopaedic sports medicine patients, and practitioners should be aware of their potential effects on treatment and performance outcomes. Management of such deficiencies and their effect on surgical patients remain an area of potential future research. Future studies are warranted in order to explore the potential therapeutic role of nutritional supplementation to prevent complications after common orthopaedic sports medicine procedures, improve athletic performance, and reduce injury rates.

Distance running is one of the most popular physical activities, and running-related injuries (RRIs) are also common. Foot strike patterns have been suggested to affect biomechanical variables related to RRI risks.

To determine the effects of foot strike techniques on running biomechanics.

The databases of Web of Science, PubMed, EMBASE, and EBSCO were searched from database inception through November 2018.

The initial electronic search found 723 studies. Of these, 26 studies with a total of 472 participants were eligible for inclusion in this meta-analysis.

Systematic review and meta-analysis.

Level 4.

Means, standard deviations, and sample sizes were extracted from the eligible studies, and the standard mean differences (SMDs) were obtained for biomechanical variables between forefoot strike (FFS) and rearfoot strike (RFS) groups using a random-effects model.

FFS showed significantly smaller magnitude (SMD, −1.84; 95% CI, −2.29 to −1.38; P < 0.001) and loading rate (mean: SMD, −2.1; 95% CI, −3.18 to −1.01; P < 0.001; peak: SMD, −1.77; 95% CI, −2.21 to −1.33; P < 0.001) of impact force, ankle stiffness (SMD, −1.69; 95% CI, −2.46 to −0.92; P < 0.001), knee extension moment (SMD, −0.64; 95% CI, −0.98 to −0.3; P < 0.001), knee eccentric power (SMD, −2.03; 95% CI, −2.51 to −1.54; P < 0.001), knee negative work (SMD, −1.56; 95% CI, −2.11 to −1.00; P < 0.001), and patellofemoral joint stress (peak: SMD, −0.71; 95% CI, −1.28 to −0.14; P = 0.01; integral: SMD, −0.63; 95% CI, −1.11 to −0.15; P = 0.01) compared with RFS. However, FFS significantly increased ankle plantarflexion moment (SMD, 1.31; 95% CI, 0.66 to 1.96; P < 0.001), eccentric power (SMD, 1.63; 95% CI, 1.18 to 2.08;P < 0.001), negative work (SMD, 2.60; 95% CI, 1.02 to 4.18; P = 0.001), and axial contact force (SMD, 1.26; 95% CI, 0.93 to 1.6; P < 0.001) compared with RFS.

Running with RFS imposed higher biomechanical loads on overall ground impact and knee and patellofemoral joints, whereas FFS imposed higher biomechanical loads on the ankle joint and Achilles tendon. The modification of strike techniques may affect the specific biomechanical loads experienced on relevant structures or tissues during running.

There is a renewed interest in diagnosing and treating subscapularis tears, but there is a paucity of clinical guidance to optimize diagnostic decision-making.

To perform a literature review to evaluate advanced maneuvers and special tests in the diagnosis of subscapularis tears and create a diagnostic algorithm for subscapularis pathology.

PubMed, MEDLINE, Ovid, and Cochrane Reviews databases.

Inclusion criteria consisted of level 1 and 2 studies published in peer-reviewed scientific journals that focused on physical examination.

Systematic review.

Level 2.

Individual test characteristics (bear hug, belly press, lift-off, Napoleon, and internal rotation lag sign) were combined in series and in parallel to maximize clinical sensitivity and specificity for any special test evaluated in at least 2 studies. A secondary analysis utilized subjective pretest probabilities to create a clinical decision tree algorithm and provide posttest probabilities.

A total of 3174 studies were identified, and 5 studies met inclusion criteria. The special test combination of the bear hug and belly press demonstrated the highest positive likelihood ratio (18.29). Overall, 3 special test combinations in series demonstrated a significant impact on posttest probabilities. With parallel testing, the combination of bear hug and belly press had the highest sensitivity (84%) and lowest calculated negative likelihood ratio (0.21).

The combined application of the bear hug and belly press physical examination maneuvers is an optimal combination for evaluating subscapularis pathology. Positive findings using this test combination in series with a likely pretest probability yield a 96% posttest probability; whereas, negative findings tested in parallel with an unlikely pretest probability yield a 12% posttest probability.

Suspension training systems, which use body weight resistance under unstable conditions, may be effective for muscle strengthening in persons with scapular dyskinesis or subacromial impingement syndrome.

Greater arm, scapular, and trunk muscle recruitment will occur during horizontal abduction row exercises.

Descriptive laboratory study.

Level 5.

Surface electromyography data were collected from 28 participants (14 men, 14 women). A total of 13 right-sided muscles were studied at a sampling frequency of 1000 Hz. Maximal voluntary isometric contractions (MVICs) were established. Participants completed 3 repetitions per exercise in random order. We compared muscle recruitment during 3 rowing exercises: low row, high row, and horizontal abduction row. Data were compared with repeated-measures analyses of variance and post hoc Bonferroni corrections.

For high row and horizontal abduction row conditions, the upper, middle, and lower trapezius and posterior deltoid demonstrated >60% MVIC magnitudes of recruitment, and the upper erector spinae demonstrated 40% to 60% MVIC magnitudes of recruitment, respectively. In contrast, in the low row exercise, 40% to 60% MVIC magnitudes of recruitment were observed only in the middle trapezius, latissimus dorsi, and posterior deltoid.

With the suspension system, high row and horizontal abduction row exercises promote muscle strengthening (>50% MVIC) in the upper, middle, and lower fibers of the trapezius, posterior deltoid, and upper erector spinae.

Rowing exercises performed with suspension straps may be recommended for muscle strengthening in patients with scapular dyskinesis and subacromial impingement syndrome as well as for healthy persons in need of enhanced scapular muscle performance.

The preparticipation physical evaluation (PPE) is a requirement for high school sport participation in most states, but its location and role in preventive health care for adolescents is often questioned.

Athletes who had their PPE performed in an office setting, in particular) by their primary care physician (PCP), will have higher human papillomavirus (HPV) immunization rates than those who had their PPE done in a group setting at a mass-participation PPE.

Retrospective cohort study.

Level 3.

The PPE forms and immunization records for athletes at a single high school were reviewed to determine the location of PPE, the signing practitioner, and HPV immunization status.

A total of 488 athletes (286 males, 202 females) were included; 51% had received at least 1 dose of the HPV vaccine while 39% had completed the series. There was no significant difference in vaccination rates between examination in an office setting versus a group setting. Athletes receiving their PPE at an urgent care facility had significantly lower rates of HPV series completion than all other settings (29% vs 43%; P = 0.004). PPE completion by the athlete’s PCP was associated with higher rates of vaccine series completion (46% vs 34%; P = 0.014).

Athletes who completed their PPE in mass event and office-based settings had similar rates of HPV vaccine series initiation and completion. PPEs done at urgent care facilities were associated with low rates of vaccine series completion, while those done by a PCP were associated with higher rates.

HPV immunization rates in athletes are low, and the PPE represents a potential opportunity to improve immunization rates.