Association of Ankle Dorsiflexion and Landing Forces in Jumping Athletes

Background: Dorsiflexion range of motion restriction has been associated with patellar tendinopathy, but the mechanisms of how dorsiflexion restriction could contribute to knee overload remain unknown. Hypothesis: Peak ankle dorsiflexion and ankle dorsiflexion excursion are negatively associated with peak vertical ground-reaction force (vGRF) and loading rate, and with peak patellar tendon force and loading rate, and positively associated with peak ankle plantar flexor moment. Study Design: Cross-sectional study. Level of Evidence: Level 4. Methods: Kinematic and kinetic data of 26 healthy recreational jumping athletes were measured during a single-leg drop vertical jump. Pearson’s correlation coefficients were calculated to establish the association between peak ankle dorsiflexion and ankle dorsiflexion excursion with peak vGRF and vGRF loading rate, with peak patellar tendon force and patellar tendon force loading rate, and with peak ankle plantar flexor moment. Results: Ankle dorsiflexion excursion negatively correlated with peak vGRF loading rate ( r = −0.49; P = 0.011) and positively correlated with peak ankle flexor plantar moment ( r = 0.52; P = 0.006). In addition, there was a positive correlation between peak ankle dorsiflexion and peak vGRF ( r = 0.39; P = 0.05). Conclusion: Ankle kinematics are associated with vGRF loading rate, ankle flexor plantar moment and peak vGRF influencing knee loads, but no association was observed between ankle kinematics and patellar tendon loads. Clinical Relevance: These results suggest that increasing ankle dorsiflexion excursion may be an important strategy to reduce lower limb loads during landings but should not be viewed as the main factor for reducing patellar tendon force.

Functional Rehabilitation and Return to Play After Arthroscopic Surgical Stabilization for Anterior Shoulder Instability

Background: There exists limited objective functional return-to-play criteria after surgical stabilization for anterior shoulder instability in the competitive athlete. Hypothesis: The proposed functional rehabilitation program and psychological evaluation after arthroscopic Bankart repair will help athletes return to sport with a decreased redislocation rate on return. Study Design: Case series. Level of Evidence: Level 4. Methods: Participants were contact or overhead athletes at the high school or collegiate level. Each underwent arthroscopic Bankart repair after a single dislocation event, with less than 10% glenoid bone loss. Western Ontario Shoulder Instability Index (WOSI) scores, Single Assessment Numeric Evaluation (SANE) scores, and American Shoulder and Elbow Surgeons (ASES) scores were evaluated pre- and postoperatively. Athletes were only allowed to return to competition after completing the proposed functional and psychological rehabilitation protocol. Results: A total of 62 participants were enrolled (52 male, 10 female; average age, 18.7 years (range 16-24 years); mean Instability Severity Index Score, 5.63 ± 0.55). All returned to sport for 1 full season and completed a minimum of 2 years of follow-up. The average time to pass functional testing was 6.2 ± 0.7 months, psychological testing was 5.2 ± 0.5 months, and return to sport was 6.5 ± 0.7 months. SANE scores improved from 44.3 to 90.0, ASES from 45.5 to 89.3, and WOSI from 1578.0 to 178.9 (all P < 0.001). Redislocation rate was 6.5% (4 of 62). Conclusion: The proposed functional rehabilitation and psychological assessment protocol is safe and effective in returning athletes to sport after arthroscopic surgical intervention for anterior shoulder instability. This demonstrated a low redislocation rate after 2-year follow-up. Clinical Relevance: Most return-to-play protocols after arthroscopic Bankart repair are centered on recovery time alone, with limited focus on functional rehabilitation, psychological assessment, and return-to-play testing parameters. To our knowledge, this is the first study to propose a dedicated rehabilitation program incorporating functional testing, psychological readiness, and return-to-play criteria for competitive athletes recovering from arthroscopic shoulder stabilization.

Comparing High School Sport Specialization Trends Between Division I and Club Collegiate Athletes

Background: Adolescent athletes report that sports specialization improves their ability to receive a collegiate athletics scholarship, though this is not well-understood. The purpose of this study was to examine self-reported trends in high school specialization and influences for sport participation between Division I (D-I) and college-aged club (club) athletes. Hypothesis: There would be no difference in high school sport specialization or sport participation influences between D-I and club athletes. Study Design: Retrospective cross-sectional study. Level of Evidence: Level 3. Methods: A survey included specialization classification (low, moderate, and high) for 9th to 12th grade, age that the athlete started organized sport and his or her collegiate sport, and several influential factors for participation in one’s primary high school sport (1 = no influence to 5 = extremely influential). Chi-square analyses were used to compare specialization classifications between groups. Nonparametric tests were used to determine significant differences in age-related variables and influential factors between D-I and club athletes. All analysis were also conducted with boys and girls separately. Results: Participants included 266 D-I (girls, 155; 58%) and 180 club (girls, 122; 68%) athletes. Club athletes were more likely to be classified as low specialization at every grade in high school, and this difference was more pronounced between D-I and club female athletes than male athletes. The number of years an athlete was classified as highly specialized in high school was not different between D-I and club athletes. Club athletes were more influenced by playing with friends than D-I athletes and D-I athletes were more influenced by pursuing a collegiate scholarship than club athletes. Conclusion: High levels of specialization in high school sport may not be necessary for playing at the collegiate level, though some level of specialization in high school might be necessary. Clinical Relevance: Clinicians should advocate for healthy long-term athlete development, which does not support high specialization in high school sports.

Increased Incidence of Injury Among Runners With COVID-19

Background: Coronavirus disease 2019 (COVID-19) affects multiple organ systems. Whether and how COVID-19 affects the musculoskeletal system remains unknown. We aim to assess the association between COVID-19 and risk of injury. Hypothesis: Runners who report having COVID-19 also report a higher incidence of injury. Study Design: Cross-sectional study. Level of Evidence: Level 4. Methods: An electronic survey was distributed from July through September 2020, by New York Road Runners, ASICS North America, race medical directors, and through social media. Inclusion criteria were runners 18 years or older who had participated in ≥1 race (running or triathlon) in 2019. Results: A total of 1947 runners participated and met inclusion criteria. Average age was 45.0 (SD, 12.2) years and 56.5% were women. A total of 123 (6.3%) runners self-reported having COVID-19; 100 (81%) reported their diagnosis was from a laboratory test (polymerase chain reaction or antibody) and 23 reported being diagnosed by a medical professional without confirmatory laboratory testing. Since March 2020, 427 (21.9%) reported an injury that prevented running for at least 1 week, including 38 of 123 (30.9%) who self-reported having COVID-19 and 389 of 1435 (21.3%) who did not report having COVID-19 ( P = 0.01). After adjusting for age, sex, the number of races in 2019, and running patterns before March 2020, runners who self-reported a diagnosis of COVID-19 had a higher incidence of injury compared with those who did not (odds ratio, 1.66; 95% CI, 1.11-2.48; P = 0.01). Conclusion: Injuries were more often self-reported by runners with laboratory-confirmed or clinically diagnosed COVID-19 compared with those who did not report COVID-19. Given the limitations of the study, any direct role of COVID-19 in the pathophysiology of injuries among runners remains unclear. Clinical Relevance: Direct and indirect musculoskeletal sequelae of COVID-19 should be further investigated, including the risk of exercise- and sports-related injury after COVID-19.

ACL Reconstruction Rehabilitation: Clinical Data, Biologic Healing, and Criterion-Based Milestones to Inform a Return-to-Sport Guideline

Context: Anterior cruciate ligament (ACL) reconstruction (ACLR) and postoperative rehabilitation continues to be a multidisciplinary focus in both research and clinical environments. Recent research on ACLR warrants a reexamination of clinicians’ current rehabilitation practices to optimize the strikingly variable clinical outcomes after ACLR and return to sport. The purpose of the article and updated guidelines is to use contemporary evidence to systematically revisit our practice guidelines and validate our clinical milestones with data from our university-based practice. Evidence Acquisition: Using the PubMed search engine, articles that reported on ACLR rehabilitation and protocols, guidelines, graft type, healing and strain, return to sport, psychological considerations, and secondary injury prevention published from 1979 to 2020 were identified using the search terms ACLR protocols, guidelines, ACLR rehabilitation, ACL graft, ACL open kinetic chain (OKC) exercise and closed kinetic chain (CKC) exercise, ACLR return to sport, ACLR psychological factors, and ACL injury prevention. Study Design: Clinical review. Level of Evidence: Level 5. Results: Clinical milestones after ACLR were validated using clinical data collected from 2013 to 2017 at a university-based practice. Variables including knee joint range of motion, effusion, Knee Outcome Survey–Activities of Daily Living Scale, and quadriceps strength index were tracked throughout rehabilitation and analyzed to help inform an updated ACLR rehabilitation guideline. Conclusion: Incorporating the latest research, combined with direct clinical data, provides a current, realistic, and clinically benchmarked strategy for ACLR rehabilitation. Commonly held clinical beliefs regarding rehabilitation after ACL injury must be challenged by the latest research to improve patient outcomes and decrease the risk of reinjury. Key updates to the practice guidelines include the use of frequent and accurate quadriceps strength testing, delayed return-to-sport timeline, immediate use of open kinetic chain exercise, criterion-based progressions for running, sprinting, plyometrics, agility, cutting/pivoting, return to competition, and the inclusion of a secondary prevention program after return to sport. Strength of Recommendation Taxonomy (SORT): B.

Effectiveness of Exercise Training on Male Factor Infertility: A Systematic Review and Network Meta-analysis

Context: Mounting evidence from the literature suggests that different types of training interventions can be successful at improving several aspects of male reproductive function in both fertile and infertile populations. Objective: The aim of this study was to evaluate the effectiveness of exercise training on male factor infertility and seminal markers of inflammation. Data Sources: We searched PubMed, CISCOM, Springer, Elsevier Science, Cochrane Central Register of Controlled Trials, Scopus, PEDro, Ovid (Medline, EMBASE, PsycINFO), Sport Discus, Orbis, CINAHL, Web of Science, ProQuest, and the ClinicalTrials.gov registry for randomized controlled trials (RCTs) that analyzed the impacts of selected types of exercise interventions on markers of male reproductive function and reproductive performance. Study Selection: A total of 336 records were identified, of which we included 7 trials reporting on 2641 fertile and infertile men in the systematic review and network meta-analysis. Level of Evidence: Level 1 (because this is a systematic review of RCTs). Data Extraction: The data included the study design, participant characteristics, inclusion and exclusion, intervention characteristics, outcome measures, and the main results of the study. Results: The results of network meta-analysis showed that, compared with a nonintervention control group, the top-ranking interventions for pregnancy rate were for combined aerobic and resistance training (CET) (relative risk [RR] = 27.81), moderate-intensity continuous training (MICT) (RR = 26.67), resistance training (RT) (RR = 12.54), high-intensity continuous training (HICT) (RR = 5.55), and high-intensity interval training (HIIT) (RR = 4.63). While the top-ranking interventions for live birth rate were for MICT (RR = 10.05), RT (RR = 4.92), HIIT (RR = 4.38), CET (RR = 2.20), and HICT (RR = 1.55). Also, with the following order of effectiveness, 5 training strategies were significantly better at improving semen quality parameters (CET > MICT > HICT > RT > HIIT), seminal markers of oxidative stress (CET > MICT > HIIT > HICT > RT), seminal markers of inflammation (CET > MICT > HIIT > RT > HICT), as well as measures of body composition and VO2max (CET > HICT > MICT > HIIT > RT). Conclusion: The review recommends that the intervention with the highest probability of being the best approach out of all available options for improving the male factor infertility was for CET.

Baseline Aerobic Fitness in High School and College Football Players: Critical for Prescribing Safe Exercise Regimens

Background: Nontraumatic fatalities occur on a regular basis in high school (HS) and college football athletes, primarily in obese linemen performing high-intensity exercise. One contributing factor to these deaths may be a mismatch between baseline aerobic (cardiorespiratory) fitness and exercise regimens. Hypothesis: There is a wide range of aerobic fitness in HS and college football players. Body mass index (BMI) is a safe and simple method for estimating baseline aerobic fitness. Study Design: Retrospective cohort study. Level of Evidence: Level 3. Methods: A retrospective review was performed on 79 HS football athletes who had VO2Peak (mL·kg−1·min−1) measured during the offseason. Multivariate regression analysis was used to determine if BMI (obese, overweight, and normal; kg/m2), position played (linemen vs other), year in school (freshmen vs other), and/or race (African American vs White) were risk factors for poor aerobic fitness. A separate cohort of 135 (48 HS; 87 college) football athletes performed a 6-minute run test to determine speed (miles/min), extrapolate VO2Max, and calculate reference values for suggested upper threshold safe starting speeds (85% of maximum) for aerobic training based on BMI. The relationship between BMI and VO2Peak was assessed. The exercise regimens (speeds) of 2 collegiate football fatalities from the public domain were used to predict their VO2Max values. Results: Mean VO2Peak (mL·kg−1·min−1) was 38.5 ± 8.6 (range 19.1-60.6); when grouped by BMI, low scores (<40) were found in 87.5% of obese (32.4 ± 7.7), 47.8% of overweight (40.8 ± 7.6), and 45.2% of normal (41.4 ± 7.8) athletes. VO2Peak was significantly lower in linemen (32.8 ± 6.4; P = 0.007) compared with nonlineman (41.8 ± 7.9), and in obese players (by BMI; 32.4; P = 0.019) compared with nonobese players (41.4 ± 7.6), but did not differ by age, year in school, or race. Means for speed (min/mile) and extrapolated VO2Max (mL·kg−1·min−1) for the 6-minute run test by BMI groups were both significantly different ( P = 0.001) for normal (7.0 ± 0.6; 51.1 ± 2.6), overweight (7.6 ± 0.8; 46.5 ± 3.2), and obese (8.9 ± 1.5; 36.8 ± 5.9) athletes. There was a significant negative correlation ( r = −0.551; P = 0.001; R2 = 0.304) between VO2Peak and BMI. Safe starting speed recommendations for running 1 mile range from 7.3 to 12.1 min/mile for BMIs 20 to 40 kg/m2 for HS and college athletes. For the 2 fatalities (mean, BMI of 36.5 kg/m2) repetitive sprint speeds were 49 and 89% higher than our safe starting speeds for their BMI. Conclusion: A large spectrum of baseline aerobic fitness was noted in HS and college football players. Obese players and linemen had statistically lower baseline aerobic fitness, a major risk factor for possible heat illness. BMI is an acceptable surrogate for VO2Peak and can be employed to develop safe training regimens without the need for a maximum fitness test, which can place the athlete at risk for a medical event. Clinical Relevance: Knowledge of BMI provides an estimate of baseline aerobic fitness and a foundation for prescribing safe, individualized exercise regimens.

Weightlifting for Children and Adolescents: A Narrative Review

The involvement of youth in the sport of weightlifting and the use of weightlifting methods as part of training for youth sport performance appears to be increasing. Weightlifting for children and adolescents has been criticized in some circles and is a controversial aspect of resistance training for young people. Although injuries can occur during weightlifting and related activities, the incidence and rate of injury appear to be relatively low and severe injury is uncommon. A number of performance, physical, and physiological variables, such as body composition, strength, and power, are improved by weightlifting training in children, adolescents, and young athletes. Manipulating program variables, when appropriate, can have a substantial and profound influence on the psychological, physiological, physical, and performance aspects of weightlifters. An understanding of the sport, scientific training principles, and musculoskeletal growth development is necessary to properly construct a reasonable and appropriate training program. A scientific background aids in providing an evidenced basis and sound rationale in selecting appropriate methods and directing adaptations toward more specific goals and enables the coach to make choices about training and competition that might not otherwise be possible. If weightlifting training and competition are age group appropriate and are properly supervised, the sport can be substantially safe and efficacious.

Chronic Workload, Subjective Arm Health, and Throwing Injury in High School Baseball Players: 3-Year Retrospective Pilot Study

Background: Baseball workloads are monitored by pitch counts, appearances, innings per appearance, ball velocity, and distance, whereas current workload standards neglect throws made during nongame situations. The association between total workloads, subjective measures, and injury in baseball is poorly understood. The question remains whether baseball athletes are at higher risk of injury by throwing more often or if they generate injury resilience when appropriately transitioned into the higher demands of throwing. Hypothesis: Increased chronic load, along with subjective arm health measures, are related to decreased injury risk. Study Design: Clinical research. Level of evidence: Level 3. Methods: A total of 49 male baseball players (age 17.9 ± 0.4 years, height 181.8 ± 6.8 cm, body mass 80.6 ± 9.1 kg) competing at the varsity high school level were included in this 3-year retrospective data analysis from 2016 to 2019. Players wore the motusTHROW sleeve and sensor during all throwing activities. Results: A total of 898,492 throws and 9455 athletic exposures were captured with the motusTHROW sensors. There were 24 injuries recorded throughout the 3-year analysis, with 11 throwing-related and 13 non–throwing related injuries. Results of the 1-way analysis of variance found chronic load was significantly related to throwing-injury occurrence ( P < 0.01). Six of the throwing-related injuries occurred when athletes had a chronic load greater than 11.3, marking 75th percentile across all observations. There was a relationship between arm health and throwing arm–related injury occurrence ( P < 0.01). Higher chronic load was associated with increased throwing-related injuries even when adjusted for arm health ( P = 0.01). Specifically, injuries were more likely to occur in pitchers (either as a combination player or pitcher only) with a chronic load greater than 9.2. Conclusion: This study revealed a significant relationship between chronic load, subjective arm health, and throwing-related injury in varsity high school baseball players. Contrary to our hypothesis, increased chronic load was associated with increased injury risk. However, subjective arm health measures remain a relevant factor in assessing injury risk. Normative data for this population also provide key information around positional demands along with overall demands of the sport during the competitive season and off-season.