Timothy C. Mauntel

The effects of lower extremity muscle activation and passive range of motion on single leg squat performance.

Abstract Mauntel, TC, Begalle, RL, Cram, TR, Frank, BS, Hirth, CJ, Blackburn, T, and Padua, DA. The effects of lower extremity muscle activation and passive range of motion on single leg squat performance. J Strength Cond Res 27(7): 1813–1823, 2013—Knee valgus is a potential risk factor for lower extremity (LE) injuries. Clinical movement screenings and passive range of motion (PROM) measurements may help identify neuromuscular patterns, which contribute to knee valgus. The purpose of this study was to compare LE muscle activation and PROM between subjects who display visual medial knee displacement (MKD) during a single leg squat (SLS) and those who do not. We hypothesized that muscular activation and PROM would differ between the groups. Forty physically active adults (20 controls, 20 MKDs) participated in this study. Subjects completed 10 LE PROM assessments and performed 5 SLS trials while electromyography (EMG) data were collected from 8 LE muscles. Three separate multivariate analysis of variance were used to identify group differences in EMG data, muscle coactivation, and PROM. Results during the SLS indicated hip coactivation ratios revealed smaller gluteus medius to hip adductor (GMed:Hip Add) (p = 0.028) and gluteus maximus to hip adductor (GMax:Hip Add) coactivation ratios (p = 0.007) compared with the control group. Also, the MKD group displayed significantly less passive ankle dorsiflexion with the knee extended (p = 0.047) and flexed (p = 0.034), and greater talar glide motion (p = 0.012). The findings of this study indicate that MKD during a SLS seems to be influenced by decreased coactivation of the gluteal to the hip adductor muscles and restricted dorsiflexion. Therefore, conditioning, rehabilitation, and injury prevention programs should focus on decreasing hip adductor activity, increasing hip abductor and external rotator activity, and increasing ankle dorsiflexion in hopes to decrease the incidence of these injuries.

The Epidemiology of Lateral Ligament Complex Ankle Sprains in National Collegiate Athletic Association Sports

Background: Ankle sprains are a common injury in collegiate sports. Few studies have examined the epidemiology of individual ligament injuries, specifically the lateral ligament complex (LLC) of the ankle. Purpose: To describe the epidemiology, including the estimated yearly national incidence, of LLC sprains among National Collegiate Athletic Association (NCAA) athletes. Study Design: Descriptive epidemiology study. Methods: Injury surveillance data for 25 sports from the NCAA Injury Surveillance Program (NCAA-ISP) for the academic years 2009-2010 to 2014-2015 were used for analysis. All injuries included for analysis had a diagnosis of an LLC sprain. LLC sprain rates and rate ratios (RRs) with 95% CIs were calculated. From the sample, national estimates of the annual incidence of LLC sprains across the entire student-athlete body from these 25 sports were also calculated. Results: During the 2009-2010 to 2014-2015 academic years, 2429 LLC sprains were reported, for a rate of 4.95 per 10,000 athlete-exposures (AEs). LLC sprains comprised 7.3% of all reported collegiate sports injuries in the NCAA-ISP. Also, an estimated 16,022 LLC sprains occurred annually among the 25 sports. The sports with the highest LLC sprain rates were men’s basketball (11.96/10,000 AEs) and women’s basketball (9.50/10,000 AEs). Most LLC sprains occurred during practices (57.3%); however, the LLC sprain rate was higher in competitions than in practices (RR, 3.29; 95% CI, 3.03-3.56). Also, 11.9% of LLC sprains were identified as recurrent injuries, with the largest proportions of recurrent LLC sprains being found within women’s basketball (21.1%), women’s outdoor track (21.1%), women’s field hockey (20.0%), and men’s basketball (19.1%). In 44.4% of LLC sprains, the athlete returned to play in less than 24 hours; in 3.6%, the athlete required more than 21 days before returning to play (including those who did not return to play at all). Conclusion: LLC sprains were the most commonly reported injury diagnosis among United States collegiate student-athletes. Continued examination of interventions that aim to reduce the incidence, severity, and recurrence of LLC sprains, specifically in women, is warranted.

Kinematic Differences Between Those With and Without Medial Knee Displacement During a Single-leg Squat

A greater knee valgus angle is a risk factor for lower extremity injuries. Visually observed medial knee displacement is used as a proxy for knee valgus motion during movement assessments in an attempt to identify individuals at heightened risk for injury. The validity of medial knee displacement as an indicator of valgus motion has yet to be determined during a single-leg squat. This study compared three-dimensional knee and hip angles between participants who displayed medial knee displacement (MKD group) during a single-leg squat and those who did not (control group). Participants completed five single-leg squats. An electromagnetic motion tracking system was used to quantify peak knee and hip joint angles during the descent phase of each squat. MANOVA identified a difference between the MKD and control group kinematics. ANOVA post hoc testing revealed greater knee valgus angle in the MKD (12.86 ± 5.76) compared with the control (6.08 ± 5.23) group. There were no other differences between groups. Medial knee displacement is indicative of knee valgus motion; however, it is not indicative of greater knee or hip rotation, or hip adduction. These data indicate that clinicians can accurately identify individuals with greater knee valgus angle through visually observed medial knee displacement.

Sex Differences During an Overhead Squat Assessment.

A disparity exists between the rates of male and female lower extremity injuries. One factor that may contribute to this disparity is high-risk biomechanical patterns that are commonly displayed by females. It is unknown what biomechanical differences exist between males and females during an overhead squat. This study compared lower extremity biomechanics during an overhead squat and ranges of motion between males and females. An electromagnetic motion tracking system interfaced with a force platform was used to quantify peak lower extremity kinematics and kinetics during the descent phase of each squat. Range of motion measurements were assessed with a standard goniometer. Differences between male and female kinematics, kinetics, and ranges of motion were identified with t tests. Males displayed greater peak knee valgus angle, peak hip flexion angle, peak vertical ground reaction forces, and peak hip extension moments. Males also displayed less active ankle dorsiflexion with the knee extended and hip internal and external rotation than females. No other differences were observed. The biomechanical differences between males and females during the overhead squat may result from differences in lower extremity ranges of motion. Therefore, sex-specific injury prevention programs should be developed to improve biomechanics and ranges of motion.

Effectiveness of Myofascial Release Therapies on Physical Performance Measurements: A Systematic Review

The muscular and skeletal systems work interdependently to provide effi cient movement. Effi cient movement can be inhibited by fascial restrictions and myofascial trigger points (MTrP). Myofascial release therapies target fascial restrictions and MTrPs to increase range of motion (ROM) and muscle function prior to rehabilitation or physical activity. A systematic review was needed to examine the eff ectiveness of these therapies so that clinicians and athletes may use only the most effi cacious methods. A search of PubMed, SPORTDiscus, CINAHL, and Cochrane Library electronic databases was completed to identify articles; 10 articles were included. All but 2 studies observed a signifi cant increase in ROM, whereas no study observed a signifi cant change in muscle function following treatment. Therefore, clinicians should use myofascial release therapies prior to rehabilitation or physical activity, as they eff ectively increase ROM without decreasing muscular function, resulting in increased movement effi ciency and decreased injury risk. [Athletic Training & Sports Health Care. 2014;6(4):189-196.] The musculoskeletal system is an intricate network of interconnecting and independent tissues that must work together effectively to provide efficient movement. When muscles and fascia are subjected to microtrauma, fascial restrictions may form and inhibit normal muscular function.1-3 Myofascial trigger points (MTrP) may develop independently or in conjunction with fascial restrictions, resulting in inhibition of normal muscular function.4 Intraand extramuscular fascia may become restrictive and create deficits in muscular function. These deficits manifest as decreased joint range of motion (ROM), altered neuromuscular properties, and decreased strength.1-3 In addition, fascia may contract as part of an evolutionary adaptation that prepares the body for activity, as well as to attempt to protect the body from repetitive stresses by providing increased stability to the musculoskeletal system.2 These adaptations can increase perimysium thickness, resulting in greater decreases in ROM.3 Myofascial trigger points may form in conjunction with fascial restrictions or may form independently. Myofascial trigger points are hyperirritable areas within taut bands of skeletal muscle or fascia that can further decrease ROM and inhibit the strength of the affected muscle.4 Myofascial trigger points are subdivided into active and latent categories; active MTrPs cause pain and irritation during rest and activity, whereas latent MTrPs generate pain only when palpated and during activity.4 Collectively, myofascial restrictions and MTrPs can contribute to dysfunctional movement patterns1-4 that can increase an individual’s injury risk. A number of soft tissue manual therapies have been developed to address fascial restrictions and MTrPs to restore normal ROM and muscular function. These manual therapies are commonly used by sports medicine clinicians, strength and conditioning professionals, and athletes prior to rehabilitation and physical activity to improve movement efficiency through increased ROM and muscular function. Improved movement efficiency results in decreased injury risks.5 Common noninvasive therapies used by clinicians, strength and conditioning professionals, and Mr Mauntel and Dr Padua are from the Department of Exercise and Sport Science, Sports Medicine Research Laboratory, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and Dr Clark is from Fusionetics, Atlanta, Georgia. Received: September 5, 2013 Accepted: April 23, 2014 Posted Online: July 17, 2014 The authors have disclosed no potential confl icts of interest, fi nancial or otherwise. Address correspondence to Timothy C. Mauntel, MA, ATC, CES, PES, Department of Exercise and Sport Science, Sports Medicine Research Laboratory, University of North Carolina at Chapel Hill, 032 Fetzer Hall, CB #8700, Chapel Hill, NC 27599; e-mail: tmauntel@gmail.com. doi:10.3928/19425864-20140717-02

Outcomes and complications of triceps tendon repair following acute rupture in American military personnel

INTRODUCTION Triceps tendon ruptures are uncommon injuries primarily occurring in young, active males or elderly individuals with various systemic diseases. Relatively little is known about the epidemiology of this injury, or the results of surgical management in high-demand populations. The purpose of this study was to define the incidence and outcomes of surgical treatment in active duty American military personnel. PATIENTS AND METHODS The Military Data Repository (MDR) was queried for all active duty military personnel undergoing surgical repair or reconstruction of a triceps tendon rupture between January 2012 and December 2014. The electronic health records of all patients with at least 12 months clinical follow-up were searched for demographic information, injury details, preoperative imaging findings, post-operative complications, and ability to return to duty following surgical repair. Incidence was calculated based on total active duty population in the MDR over the study period. Risk factors for postoperative complication and inability to return to duty following surgical repair were assessed using univariate analyses. RESULTS A total of 54 acute triceps tendon ruptures were identified in the search, of which 48 had at least 12 months follow-up and complete post-operative records. The incidence of acute triceps tendon rupture was 1.1 per 100,000 person-years. Twelve patients experienced post-operative complications, six of which were traumatic re-ruptures within four months of the index surgery. No patient had a post-operative infection or atraumatic repair failure. 94% of patients were able to return to active military service following surgical repair. Enlisted rank was a significant risk factor for a post-operative complication, but no factor predicted inability to return to active duty service. CONCLUSIONS Surgical repair of acute triceps tendon ruptures reliably restores strength and function even in high-demand individuals. In our population, traumatic rerupture was the most common complication.

The Epidemiology of High Ankle Sprains in National Collegiate Athletic Association Sports

Background: Ankle sprains are among the most common injuries experienced by collegiate athletes. The type of ankle sprain is rarely differentiated in epidemiological studies. This differentiation is necessary, as each ankle sprain type has a unique injury mechanism and recovery period. High ankle sprains commonly result in long recovery periods. Thus, a further examination of the epidemiology of high ankle sprains is warranted. Purpose: To describe the epidemiology of high ankle sprains in National Collegiate Athletic Association (NCAA) sports during the 2009/2010-2014/2015 academic years. Study Design: Descriptive epidemiology study. Methods: NCAA Injury Surveillance Program high ankle sprain data and athlete-exposures (AEs) from 25 sports were evaluated. Certified athletic trainers recorded sport-related injury, event, and AE data during team-sanctioned events. High ankle sprain injury rates per 10,000 AEs were calculated. Percentage distributions were calculated for the amount of time lost from sport and percentage of recurrent injuries. Injury rate ratios (RRs) and 95% CIs compared injury rates by event type, participation restriction time, and sex. 95% CIs not containing 1.00 were considered statistically significant. Results: The overall high ankle sprain injury rate was 1.00 per 10,000 AEs. Overall, 56.7% of high ankle sprain injuries occurred during competitions, and 9.8% of high ankle sprain injuries were recurrent. Men’s football (2.42/10,000 AEs), wrestling (2.11/10,000 AEs), and ice hockey (1.19/10,000 AEs) had the highest high ankle sprain injury rates. In sex-comparable sports, men had higher injury rates (RR, 1.77; 95% CI, 1.28-2.44). Player contact was the most common injury mechanism (60.4%), and 69.0% of injuries resulted in ≥1 day of participation restriction, with 47.1% resulting in ≥7 days of participation restriction and 15.8% resulting in >21 days of participation restriction. Conclusion: High ankle sprains resulted in significant participation restriction time from sport participation. The majority of high ankle sprain injuries resulted from player contact and were observed in contact/collision sports. The large proportion of high ankle sprains resulting from player contact, specifically in male contact sports, is worthy of further investigation. Clinical Relevance: The enhanced understanding of the epidemiology of high ankle sprains provided in our study will aid clinicians in developing targeted injury prevention strategies to mitigate the negative consequences of these injuries.

Lower Extremity Musculoskeletal Injury Risk After Concussion Recovery in High School Athletes

CONTEXT   Although an association between concussion and musculoskeletal injury has been described in collegiate and professional athletes, no researchers have investigated an association in younger athletes. OBJECTIVE   To determine if concussion in high school athletes increased the risk for lower extremity musculoskeletal injury after return to activity. DESIGN   Observational cohort study. SETTING   One hundred ninety-six high schools across 26 states. PATIENTS OR OTHER PARTICIPANTS   We used data from the National Athletic Treatment, Injury and Outcomes Network surveillance system. Athletic trainers provided information about sport-related concussions and musculoskeletal injuries in athletes in 27 sports, along with missed activity time due to these injuries. MAIN OUTCOME MEASURE(S)   Three general estimating equations were modeled to predict the odds of sustaining (1) any lower extremity injury, (2) a time-loss lower extremity injury, or (3) a non-time-loss lower extremity injury after concussion. Predictors were the total number of previous injuries, number of previous concussions, number of previous lower extremity injuries, number of previous upper extremity injuries, and sport contact classification. RESULTS   The initial dataset contained data from 18 216 athletes (females = 39%, n = 6887) and 46 217 injuries. Lower extremity injuries accounted for most injuries (56.3%), and concussions for 4.3% of total injuries. For every previous concussion, the odds of sustaining a subsequent time-loss lower extremity injury increased 34% (odds ratio [OR] = 1.34; 95% confidence interval [CI] = 1.13, 1.60). The number of previous concussions had no effect on the odds of sustaining any subsequent lower extremity injury (OR = 0.97; 95% CI = 0.89, 1.05) or a non-time-loss injury (OR = 1.01; 95% CI = 0.92, 1.10). CONCLUSIONS   Among high school athletes, concussion increased the odds of sustaining subsequent time-loss lower extremity injuries but not non-time-loss injuries. By definition, time-loss injuries may be considered more severe than non-time-loss injuries. The exact mechanism underlying the increased risk of lower extremity injury after concussion remains elusive and should be further explored in future research.

Static and dynamic single leg postural control performance during dual-task paradigms

ABSTRACT Combining dynamic postural control assessments and cognitive tasks may give clinicians a more accurate indication of postural control under sport-like conditions compared to single-task assessments. We examined postural control, cognitive and squatting performance of healthy individuals during static and dynamic postural control assessments in single- and dual-task paradigms. Thirty participants (female = 22, male = 8; age = 20.8 ± 1.6 years, height = 157.9 ± 13.0 cm, mass = 67.8 ± 20.6 kg) completed single-leg stance and single-leg squat assessments on a force plate individually (single-task) and concurrently (dual-task) with two cognitive assessments, a modified Stroop test and the Brooks Spatial Memory Test. Outcomes included centre of pressure speed, 95% confidence ellipse, squat depth and speed and cognitive test measures (percentage of correct answers and reaction time). Postural control performance varied between postural control assessments and testing paradigms. Participants did not squat as deep and squatted slower (P < 0.001) during dual-task paradigms (≤12.69 ± 3.4 cm squat depth, ≤16.20 ± 4.6 cm · s−1 squat speed) compared to single-task paradigms (14.57 ± 3.6 cm squat depth, 19.65 ± 5.5 cm · s−1 squat speed). The percentage of correct answers did not change across testing conditions, but Stroop reaction time (725.81 ± 59.2 ms; F2,58 = 7.725, P = 0.001) was slowest during single-leg squats compared to baseline (691.64 ± 80.1 ms; P = 0.038) and single-task paradigms (681.33 ± 51.5 ms; P < 0.001). Dynamic dual-task assessments may be more challenging to the postural control system and may better represent postural control performance during dynamic activities.

Kinematic and neuromuscular relationships between lower extremity clinical movement assessments

Abstract Lower extremity injuries have immediate and long-term consequences. Lower extremity movement assessments can assist with identifying individuals at greater injury risk and guide injury prevention interventions. Movement assessments identify similar movement characteristics and evidence suggests large magnitude kinematic relationships exist between movement patterns observed across assessments; however, the magnitude of the relationships for electromyographic (EMG) measures across movement assessments remains largely unknown. This study examined relationships between lower extremity kinematic and EMG measures during jump landings and single leg squats. Lower extremity three-dimensional kinematic and EMG data were sampled from healthy adults (males = 20, females = 20) during the movement assessments. Pearson correlations examined the relationships of the kinematic and EMG measures and paired samples t-tests compared mean kinematic and EMG measures between the assessments. Overall, significant moderate correlations were observed for lower extremity kinematic (ravg = 0.41, rrange = 0.10–0.61) and EMG (ravg = 0.47, rrange = 0.32–0.80) measures across assessments. Kinematic and EMG measures were greater during the jump landings. Jump landings and single leg squats place different demands on the body and necessitate different kinematic and EMG patterns, such that these measures are not highly correlated between assessments. Clinicians should, therefore, use multiple assessments to identify aberrant movement and neuromuscular control patterns so that comprehensive interventions can be implemented.