Impaired Core Stability as a Risk Factor for the Development of Lower Extremity Overuse Injuries: A Prospective Cohort Study

The Running Readiness Scale and Injury in Collegiate Track and Field and Cross Country Athletes

CONTEXT

Track and field and cross country athletes experience high rates of lower extremity injuries. The Running Readiness Scale (RRS) may help determine which athletes have a higher likelihood of lower extremity injury.

OBJECTIVE

To determine if RRS performance at the start of the season was related to the likelihood of experiencing a lower extremity injury during the subsequent track and field or cross country season.

DESIGN

Prospective cohort study.

SETTING

University.

PATIENTS OR OTHER PARTICIPANTS

One hundred thirteen National Collegiate Athletic Association Division III track and field athletes in running, jumping, and vaulting events and cross country runners (50 women and 63 men, age = 19.9 ± 1.3 years [mean ± SD]).

MAIN OUTCOME MEASURE(S)

Athletes were assessed on RRS tasks (double-leg hopping, plank, step-ups, single-leg squats, and wall sit) at the start of their season and were then observed by team athletic trainers during the season for occurrence of lower extremity injuries that resulted in missing 1 or more practices or meets. Adjusted odds ratios and 95% confidence intervals were used to assess the likelihood of lower extremity injury.

RESULTS

Thirty-seven athletes (32.7%) experienced a lower extremity injury. Athletes scoring ≤3 on the RRS were almost 5 times more likely to experience a lower extremity injury (adjusted odds ratios = 4.8; 95% confidence interval: 2.1, 11.3) than athletes scoring ≥4. Athletes who failed the double-leg hop or wall sit task were more likely to experience a lower extremity injury (P < .05).

CONCLUSIONS

Track and field and cross country athletes with RRS scores of ≤3 had a higher likelihood of lower extremity injury than those with scores of ≥4.

A Critical Review of Trunk and Hip Exercise Prescription: Applying Evidence for a Modern Approach

Exercise targeting the trunk and hip (core) musculature is common practice in rehabilitation and performance training. Historical underpinnings of core exercise focus on providing stability to the spine, thus improving the function of the spine and extremities, while instability has been postulated to result in pathology and impaired performance. Mechanistic studies on the topic are often conflicting and indeterminate, suggesting the theoretical underpinnings of targeted core exercise may be over assumed in common practice. The best modes of intervention also remain undefined, with combined methods having potential to optimize outcomes. This includes moving beyond isolated exercise camps and being inclusive of both targeted exercise and progressive multi-joint movements. The purpose of this clinical commentary is to describe the historical mechanisms of the stability-instability continuum and the role of exercise intervention. A spectrum of ideologies related to core exercise are examined, while appreciating positive outcomes of exercise interventions across healthy and pathological populations. Finally, exercise summaries were compiled to improve critical reasoning within current practice and inspire future investigations.

Level of Evidence

5.

The Effects of Different Core Stability Training on Trunk Stability and Athletic Performance in Adolescent Female Basketball Players

PURPOSE

Trunk function is not only related to physical fitness performance, but also important for the balance, and stability of the whole body. This study aimed to investigate the effects of 2 training methods on trunk stability and athletic performance in adolescent female basketball players.

METHODS

Fifty-one healthy elite female basketball players (age: 14.76 [1.84] y, body mass index: 21.41 [1.96] kg/m2) were assigned to TRX training (n = 17), Swiss ball training (n = 17), or control groups (n = 17). Participants performed a progressive program of unstable core muscle training consisting of 8 different exercises, with each exercise performed in 3 sets, twice a week for 8 weeks. The outcome measures were a plank test, the modified double leg lowering task, and athletic performance including jumping, speed, agility, cardiopulmonary endurance, and the ankle proprioception.

RESULTS

Significant group and time interaction were identified in the modified double leg lowering task (P = .032, η2 = .134), with post hoc comparisons revealing improvements in the TRX group (P = .014). The TRX group (8.6%) improved significantly more than the Swiss ball group (2.9%) when it comes to the modified double leg lowering average change percentage. The plank test also exhibited a significant group and time interaction (P = .033, partial η2 = .133), with notable improvements in both the Swiss ball (P = .001) and the TRX groups (P = .001). Athletic performance measures showed no significant differences among groups.

CONCLUSIONS

The results indicate that both TRX and Swiss ball training can increase core muscle strength and stability without compromising athletic performance after 8 weeks of training. Furthermore, incorporating core muscle training enhances power transmission capabilities. Nevertheless, considering the goal was to improve speed and ankle proprioception during preseason training, careful consideration must be given to the timing and intensity of any intervention involving unstable core muscle training.

Injury Prevention Strategies in Female Football Players: Addressing Sex-Specific Risks

There has been rapid growth in women's football worldwide; however, research on injury prevention strategies and physiological considerations specific to female athletes remains insufficient. Women's football has experienced an increase in injury prevalence, despite being underrepresented in sports literature, with less than 25% of research focused on this demographic. The incidence of injuries, particularly among young elite female footballers, is notably high, impacting long-term health outcomes such as osteoarthritis and contributing to shorter playing careers. Certain injuries, such as anterior cruciate ligament (ACL) ruptures, occur at significantly higher rates in women compared to men, underscoring sex-specific risk factors that must be addressed in injury prevention programs (IPPs). This narrative review aims to evaluate the effectiveness of IPPs tailored for female football players and to address their heightened susceptibility to injuries compared to males. Research studies and review articles were identified using a literature search of the PubMed, SportDiscus, and Google Scholar databases from 1990 to December 2024. Biological factors, including hormonal influences-such as increased ACL laxity during the menstrual cycle-and musculoskeletal differences, such as muscle strength imbalances, reduced joint stability, and hip weakness, significantly contribute to this increased risk. Despite the existence of injury prevention protocols like FIFA 11+, their consistent application and adaptation to meet the unique needs of female footballers remain limited. In addition to physical injuries, mental health is a critical concern. Female football players exhibit higher rates of depression and anxiety compared to their male counterparts, influenced by factors such as injury-related stress and menstrual cycle variations. In conclusion, the growing participation of women in football highlights the urgent need for research and implementation of injury prevention strategies specifically tailored to female players.

Objective assessment of the effect of surgery on limb function after medial femoral condyle free flap harvest: biomechanical parameters

The aim of this study was to evaluate the influence of medial femoral condyle (MFC) free flap harvest on donor site muscle strength and kinematic parameters of gait. The study included 30 patients treated for head and neck squamous cell carcinoma who underwent reconstruction with an MFC free flap. In each case, the donor site was the left thigh. A dynamometer was used to measure muscle strength, in isokinetic bilateral mode and with concentric contraction for the extension/flexion knee pattern, at 18 months postoperative. In addition, kinematic data were obtained and evaluated. On statistical analysis, no significant difference in muscle strength of the quadriceps muscle was found between the left involved and right uninvolved lower extremities (P = 0.124). Also, when comparing hamstring strength, no statistically significant difference was found between the left involved and right uninvolved sides (P = 0.210). Moreover, spatiotemporal gait parameters did not differ significantly between the involved and uninvolved legs (all P > 0.05), and no differences in kinematic or kinetic parameters were observed. This study reports the effects of MFC free flap harvest on the knee muscle strength and locomotion of patients. For most biomechanical parameters investigated, there was no effect (positive or negative).

The relationship between the functional status of the extremities and "core" stabilization in women with fibromyalgia

Introduction

The aim of this study was to examine the relationship between the functional status of the extremities and "core" stabilization in women with fibromyalgia (FM).

Material and methods

Fifty-seven women with FM were included. The Widespread Pain Index (WPI), Visual Analogue Scale-Pain (VAS-Pain), Symptom Severity Scale (SSS), Fibromyalgia Impact Questionnaire (FIQ), McGill Static endurance tests (trunk flexors endurance, trunk extensors endurance, lateral bridge tests), Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH), grip strength, Lower Extremity Functional Scale (LEFS), chair-stand test, pressure pain threshold and 6-minute walk test (6MWT) were used in evaluation.

Results

The trunk flexors endurance test showed a weak correlation with 6MWT (r = 0.392), DASH (r = -0.347), LEFS (r = 0.328) and WPI (r = -0.289). The trunk extensors endurance test showed a weak correlation with grip strength-right (r = 0.285), DASH (r = -0.301) and LEFS (r = 0.321) and a moderate correlation with grip strength-left (r = 0.407), chair-stand test (r = 0.470) and 6MWT (r = 0.524). The right lateral bridge test showed a weak correlation with grip strength-right (r = 0.271), DASH (r = -0.379), LEFS (r = 0.254), WPI (r = -0.306), average of maximal values of pressure pain threshold (r = 0.316) and average of mean values of pressure pain threshold (r = 0.337); it showed a moderate correlation with grip strength-left (r = 0.418) and 6MWT (r = 0.414). The left lateral bridge test showed a weak correlation with grip strength-right (r = 0.279), chair-stand test (r = 0.276), 6MWT (r = 0.359), DASH (r = -0.294), average of maximal values of pressure pain threshold (r = 0.315) and average of mean values of pressure pain threshold (r = 0.370); it showed a moderate correlation with grip strength-left (r = 0.502) (p < 0.05).

Conslusions

Core muscle endurance is associated with upper and lower extremity functional level and pain parameters in women with FM.

Core Training for Pain Management and Functional Improvement in Patients With Patellofemoral Pain Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

The aim of the study is to investigate the effects of core strengthening exercises on pain, mobility, and lower limb muscle strength in patients with patellofemoral pain syndrome.

DESIGN

Six databases were searched from inception until August 11, 2023. Pain, function, and muscle strength-related outcomes were extracted and the quality of the studies was assessed using the PEDro scale and the level of evidence was assessed using the GRADE.

RESULTS

Nineteen studies involving 1138 patients were included. Very low-grade evidence supported the short-term pain-relieving effect of core training (standardized mean difference = -0.60, 95% confidence interval [-0.95, -0.25]), high-grade evidence supported the short-term functional improvement effects of core training (weighted mean difference = 3.61, 95% confidence interval [1.44, 5.78]), which was similarly significant within 3-12 mos of follow-up. The results of the subgroup analyses suggested that hip-knee training was most advantageous in relieving pain and enhancing motor function.

CONCLUSIONS

Although training that includes trunk core is clearly superior to knee strengthening alone, the effectiveness of hip-knee training, which is also a core training program for pain and function, is more pronounced. The available evidence supports that hip-knee training is the most valuable treatment option for patients with patellofemoral pain syndrome.

Investigation of the effect of chronic ankle instability on core stabilization, dynamic balance and agility among basketball players of a university

BACKGROUND

Chronic ankle instability (CAI) is frequently seen in basketball, where ankle sprains are common due to repetitive movements such as jumping, landing, deceleration and acceleration.

OBJECTIVE

This study investigated the effects of CAI on core stabilization, dynamic balance, and agility in university-level basketball players.

MATERIALS AND METHODS

The study included 22 basketball players with CAI (8F, 3M; 20.09 ± 1.04 years) and without CAI (8F, 3M; 21.27 ± 2.24 years), registered as team players in the Yeditepe University basketball teams. Participants divided into two groups: the chronic ankle instability group (CAIG) and the control group (CG). The participants' core stabilization was evaluated using the McGill Core Endurance Test, dynamic balance was evaluated with the Y Balance Test and the T Test was used to evaluate agility.

RESULTS

According to the results of an independent t-test, significant differences were observed between groups including posteromedial (p = 0.03) and posterolateral (p = 0.03) reach distances, trunk flexion (p = 0.04) and trunk extension (p = 0.03) tests. According to the logistic regression analysis, Y Balance Test posteromedial and posterolateral reach distances, trunk flexion and trunk extension tests in the McGill Core Endurance Test were found to be statistically significant on the presence of CAI (p < 0.05).

CONCLUSION

Including core stabilization and dynamic balance exercises in the training program may be beneficial to improve core stabilization and dynamic balance parameters and prevention of CAI in university-level basketball players with CAI.

Compensatory muscle activation and spinal curve changes in response to fatigue among adolescent male athletes

BACKGROUND

The prone plank test has been often used to assess the strength and endurance of trunk muscles. We aimed to develop a new measurement protocol to objectively monitor the changes in spinal curves and muscle activity simultaneously.

METHODS

Eleven adolescent male basketball athletes (13-17 years) performed a one-minute plank test. Spinal curvatures (thoracic kyphosis (TK) and lumbar lordosis (LL)) were determined at each time point by optical tracking of markers placed on the spinous processes of 10 vertebrae. Eleven muscles were measured by surface electromyography to determine muscle fatigue via changes in median frequency.

RESULTS

TK significantly increased (p = 0.003) from the first to the last 10 s of the plank test; changes in LL were mixed within the group. Only the rectus abdominis showed consistent and significant fatigue (p < 0.001). The increased spinal curves significantly correlated with the fatigue of biceps femoris (TK: r = -0.75, p = 0.012; LL: r = -0.71, p = 0.019) indicating a compensatory muscle activation and spinal curve changes in response to fatigue.

CONCLUSION

Our protocol may support future researches that aim to objectively evaluate the prone plank test and which posture-related muscles need strengthening for the individual.

The effects of core stabilization exercises on the neuromuscular function of athletes with ACL reconstruction

Athletes who have undergone anterior cruciate ligament reconstruction (ACLR) often exhibit persistently impaired kinematics and strength. Core stability training appears to be effective for reducing high-risk landing mechanics and preventing primary anterior cruciate ligament (ACL) injuries; however, there have been few attempts to examine their effects in athletes who have undergone ACLR. This study aimed to investigate the effect of eight weeks of simple core stability training on core endurance, hip strength, and knee kinematics in ACLR athletes. Twenty-six male athletes (20-30 years old) with a history of ACL surgery with hamstring tendon autograft were randomly divided into training (n = 13) and control groups (n = 13). The training group performed core stability exercises for eight weeks before starting their team training; the control group did not receive any intervention. Both groups continued their regular team schedule. The core endurance, hip muscle strength, and knee kinematics were assessed by the McGill test, a hand-held dynamometer, and video-taping, respectively. Analysis of covariance test was used for data analysis. The training group showed a significant increase in core endurance, hip abductor and external rotator strength, knee flexion angle, and a significant decrease in the knee valgus angle during single-leg landing in post-training tests compared to their baseline tests (P < 0.05). Our results demonstrated that core stability exercise alters neuromuscular function to a level that is clinically acceptable and statistically significant. Because of the high incidence rate of secondary ACL injury after ACLR, it is recommended that athletes with a history of ACLR benefit from adding core stability exercises to warm-up routines or tertiary prevention programs even after completing post-operative rehabilitation. It is fast and not time-consuming to perform for athletes to reduce the risk factors of re-injury. Trial registration: This study was registered in the Iranian Registry of Clinical Trials with the number IRCT20190224042827N2, registered on 19 December 2019.

The ability to produce a timely explosive force may affect loading rate at landing

Background

Sports injuries are strongly associated with the impact loading at landing. The abilities to produce force and adjust timing are simultaneously required to absorb impact loading.

Aims

Hence, we aimed to examine the hypothesis that the ability to produce an explosive force at the right timing is related to the ability to absorb the impact loading at landing.

Methods

Twenty-nine healthy young men volunteered to participate in the study. We proposed a new test to measure the rate of force development (RFD) in accordance with the countdown signal. To evaluate the ability to produce explosive force at the right time, we measured the rate of change between the RFD at the standard start signal and the RFD at the countdown signal. Furthermore, to evaluate the ability to land from a jump, we measured the loading rate at single-leg drop landing (20 cm).

Results

We divided the participants into two groups based on the timing effect: the positive group (participants with increased RFD at the countdown signal, n = 11) and the negative group (participants with decreased RFD at the countdown signal, n = 18). The loading rate was significantly greater (P < .01) in the negative group (47.4 ± 11.2 body weight (BW)/s) than in the positive group (34.7 ± 7.1 BW/s).

Conclusions

Participants with increased RFD at the countdown signal had a lower loading rate at landing. Our results suggest that the ability to produce a timely explosive force may be a determinant of safe landing ability.

FATIGUE AND REHABILITATION IN THE TRAINING OF GYMNASTS

ABSTRACT Introduction Aerobic gymnastics requires a lot of physical ability and endurance. Fatigue is an inevitable consequence of intrinsic movements with a high intensity related to the sport. Objective Analyze the rehabilitation strategy of sports fatigue in aerobic gymnastics athletes caused by training. Methods 20 volunteer aerobics students in colleges and universities were recruited and divided into experimental and control groups. High-intensity aerobic gymnastics training was performed where the experimental group used a combined exercise fatigue recovery scheme, while the control group used only traditional walking and stretching. Results Lasting 40 minutes, the post-exercise fatigue rehabilitation protocol showed a decreasing trend in muscle stress, while the control group evidenced a fluctuating decreasing trend. The recovery frequency of the experimental group was higher than that of the control group. Conclusion The combined method of rehabilitation training mentioned in this paper can better regulate the heart rate of athletes, reduce the level of fatigue, and transform passive relaxation into active sports rehabilitation, engaging the enthusiasm of sport in athletes. Therefore, the scheme proposed in this paper has better practical significance and practical value. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

SCIENTIFIC INVESTIGATION OF A TRAINING MODEL ON ATHLETE’S CORE STRENGTH

ABSTRACT Introduction The muscular structure that makes up the core is responsible for the central stabilization of the human body and controlling the movement of the body’s center of gravity. Core training is indispensable for improving physical performance in competitive sports. Objective To analyze the concepts, methods, and results of core strengthening in athletes. Methods Controlled research among several athletes for three months. The experimental group was approached with a training model for core strengthening of 30 minutes four times a week. The relationship between core strength and traditional strength training was confronted with the literature, logical analysis, and comparative analysis methods. Results After the core strength training, the athletes’ sports quality was improved, especially the abdominal strength and the strength of the dorsal muscle groups. The stability of deep core muscles, motor coordination, and core balance capacity was improved (P<0.05). Conclusion The presented model for strengthening running in athletes showed a high value of applicability and dissemination. Evidence Level II; Therapeutic Studies – Investigating the results.

Composite functional movement screen score predicts injuries in youth volleyball players: a prospective cohort study

We aimed to investigate whether composite Functional Movement Screen (FMS) test scores can predict musculoskeletal injuries (MSI) in youth volleyball players. 131 national young volleyball players (Males: n = 100, age = 16.5 years, height = 1.787 m, mass = 68.32 kg; Females: n = 31, age = 13.83 years, height = 1.684 m, mass = 65.12 kg) participated in this prospective cohort study. The FMS screen was performed before starting the season. MSI and exposure data were collected during the season via each team's certified athletic trainer. The mean FMS score and standard deviation for all volleyball players was 15.85 ± 3.31. A score of ≤ 14 was positive to predict MSI with specificity of 0.60 and sensitivity of 0.93. The odds ratio for (≤ 14/˃14) was 0.048. The relative risk for being injured was 3.46. Positive likelihood ratio was 2.34, and negative likelihood ratio was 0.11. The findings of this study demonstrated that an FMS score of ≤ 14 is an identifiable risk factor for injury in young volleyball players. The FMS can be used as a pre-season screening test to identify volleyball players who may be predisposed to sustaining MSI during the season ahead.

Effects of a 6 week core strengthening training on measures of physical and athletic performance in adolescent male sub-elite handball players

The objective was to investigate the effects of a 6-week core strengthening training within the regular handball training sessions compared to regular handball training only. Male sub-elite handball players were randomly assigned to an intervention (INT: n = 13; age: 16.9 ± 0.6 years) or a control (CON: n = 13; age: 17.2 ± 0.8 years) group. The INT group performed the "big 3" core exercises cross curls-up, side bridge (both sides), and the quadrupedal stance ("birddog exercise") triweekly for 20-30 min while the CON group conducted regular handball training only. Pre- and post-training assessments included measures of muscular endurance (Closed Kinetic Chain Upper Extremity Stability Test [CKCUEST] and the Bourban test), shoulder mobility/stability (Upper Quarter Y Balance [YBT-UQ] test), and throwing velocity. The ANCOVA revealed significant differences between means in favour of the INT group for the dorsal chain (p < 0.001,η p 2 = 0.46) and the lateral chain (left side: p = 0.015,η p 2 = 0.22; right side: p = 0.039,η p 2 = 0.17) of the Bourban test, the composite score (p = 0.024,η p 2 = 0.20) of the throwing arm reach and the inferolateral reach direction (p = 0.038,η p 2 = 0.17), and the composite score (p = 0.027,η p 2 = 0.19) of the non-throwing arm reach of the YBT-UQ. However, performance in the CKCUEST and throwing velocity did not show any group-specific changes. Therefore, 6 weeks of core strengthening training were effective in improving some components of physical but no handball-specific athletic (i.e., throwing velocity) performance in adolescent male sub-elite handball players. Practitioners may still opt for this training regimen when stimulus variability is sought or when a low load/low movement approach (e.g., during rehabilitation) is favoured.

Core muscle strength can be reliably measured using a novel isokinetic device: An intra-observer study

BACKGROUND

Core strength is an important aspect of physical fitness. A dynamometer was developed to measure isokinetic core muscle strength in multiple planes of motion. Establishing the reliability is needed before it can be used in practice.

OBJECTIVE

Examine the intra-observer reliability of a trunk isokinetic dynamometer.

METHODS

31 participants were recruited. Tests were performed twice with an interval of 5-9 days by the same observer. Testing included rotation, flexion/extension and lateral flexion at speeds of 90∘/s and 60∘/s. The main outcome measure was peak torque (PT). The secondary outcomes included peak torque angle (PTA), time to peak torque (TTPT) and compensatory torques (CompTQ). The intra-observer reliability was investigated using intraclass correlation coefficients (ICC).

RESULTS

Peak torque reliability was good to excellent (ICC = 0.70-0.91), whereas the reliability of the PTA (ICC =-0.04-0.56) and TTPT (ICC = 0.01-0.68) were poor to moderate. CompTQ reliability was moderate to good (ICC = 0.20-0.88).

CONCLUSIONS

The intra-observer reliability of the isokinetic measurement of core strength peak torque was good. The secondary outcomes peak torque angle and time to peak torque were less reliable and the compensatory torques showed moderate to good reliability. This isokinetic dynamometer could have useful applications in the field of sports medicine and rehabilitation.

Plank Times and Lower Extremity Overuse Injury in Collegiate Track-and-Field and Cross Country Athletes

Trunk muscle endurance has been theorized to play a role in running kinematics and lower extremity injury. However, the evidence examining the relationships between static trunk endurance tests, such as plank tests, and lower extremity injury in athletes is conflicting. The purpose of this study was to assess if collegiate cross country and track-and-field athletes with shorter pre-season prone and side plank hold times would have a higher incidence of lower extremity time-loss overuse injury during their competitive sport seasons. During the first week of their competitive season, 75 NCAA Division III uninjured collegiate cross country and track-and-field athletes (52% female; mean age 20.0 ± 1.3 years) performed three trunk endurance plank tests. Hold times for prone plank (PP), right-side plank (RSP) and left-side plank (LSP) were recorded in seconds. Athletes were followed prospectively during the season for lower extremity overuse injury that resulted in limited or missed practices or competitions. Among the athletes, 25 (33.3%) experienced a lower extremity overuse injury. There were no statistically significant mean differences or associations found between PP, RSP or LSP plank test hold times (seconds) and occurrence of lower extremity overuse injury. In isolation, plank hold times appear to have limited utility as a screening test in collegiate track-and-field and cross country athletes.

Thirty Minutes Identified as the Threshold for Development of Pain in Low Back and Feet Regions, and Predictors of Intensity of Pain during 1-h Laboratory-Based Standing in Office Workers

This study with 40 office workers investigated (a) the effect of time spent standing on low- back and lower limb pain during a 1-h laboratory-based task; (b) the standing time after which a significant increase in pain is likely; and (c) the individual, physical and psychosocial factors that predict pain. The primary outcome was bodily location of pain and pain intensity on a 100-mm Visual Analogue Scale recorded at baseline and every 15 min. Physical measures included trunk and hip motor control and endurance. Self-report history of pain, physical activity, psychosocial job characteristics, pain catastrophizing and general health status were collected. Univariate analysis and regression models were included. The prevalence of low-back pain increased from 15% to 40% after 30 min while feet pain increased to 25% from 0 at baseline. The intensity of low-back and lower limb pain also increased over time. A thirty-minute interval was identified as the threshold for the development and increase in low-back and feet pain. Modifiable factors were associated with low-back pain intensity-lower hip abductor muscle endurance and poorer physical health, and with feet symptoms-greater body mass index and less core stability.

Age and Gender Differences in Injuries and Risk Factors in Elite Junior and Professional Tennis Players

BACKGROUND

Elite tennis athletes experience injuries throughout the entire body. Impairments in trunk stability, lower limb flexibility, and hip range of motion (ROM) are modifiable risk factors that can impact injuries and performance. Information on nonmodifiable risk factors such as age and gender is limited. The purpose of this investigation was to provide information on risk factors to direct clinical decision-making and injury prevention and rehab programming in this population.

HYPOTHESIS

Prevalence and location of injuries will differ by age group and gender. Trunk stability, lower limb flexibility, and hip ROM will differ by age group and gender.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A de-identified database (n = 237; females = 126) from the United States Tennis Association High Performance Profile (HPP) 2014-2015 was used for the analysis. Subjects were elite junior and professional tennis players (mean age 14.6 [range, 9-27] years). The HPP is a tennis-specific assessment and questionnaire that includes retrospective information on injury history. Subjects were categorized by injury, gender, and age. Injury locations were classified by region. Trunk stability measures included drop vertical jump (DVJ), single-leg squat, and prone and side planks. Lower limb measures included hamstring, quadriceps and hip flexor flexibility, and hip rotation ROM.

RESULTS

A total of 46% of athletes reported an injury. Significant differences were found for injury prevalence and location by age group. Adolescent athletes (age 13-17 years) had more trunk injuries, while adult athletes (age ≥18 years) had more lower limb injuries. Adolescent athletes performed worse on DVJ, dominant side plank, and hamstring flexibility compared with young (age ≤12 years) and adult athletes. Significant gender differences in hip ROM included internal rotation on both the dominant and nondominant sides.

CONCLUSION

Impairments in trunk stability, lower limb flexibility, and hip rotation ROM may affect both health and performance outcomes in this population. Elite tennis athletes may benefit from additional off court programming to address trunk and lower limb impairments.

CLINICAL RELEVANCE

Adolescent elite tennis athletes may be at higher risk of trunk injuries. Age, gender, injury history, and impairments should be considered with all assessments and programming.

Analysis of the Stability of the Body in a Standing Position When Shooting at a Stationary Target-A Randomized Controlled Trial

Postural stability of the body depends on many factors. One of them is physical activity. It is especially important in the case of sports or professional work, which combine mobility with the accuracy of a shot in a standing position. The smaller the body fatigue, the more accurate the shot. The aim of the study was the assessment of the impact of physical effort on the center of gravity deflection and length of the COP (center of pressure) path, as well as the reaction of ground forces in people who do not engage in systematic physical activity. The study group included 139 people (23.1 ± 5.2 yr; M: 46.8%; F: 53.2%). The test consisted of performing a static test twice, shooting at the target in a multimedia shooting range. Group X performed the Harvard test between the static tests. Group Y made no effort. The reaction parameters of the ground forces were assessed using the Zebris PDM-L Platform. In Group X performing the Harvard test, an increase in the average COP, VCOP, and 95% confidence ellipse area was noted. The path length and the average velocity of COP speed increased. There were no differences in Group Y (p > 0.05). Physical effort significantly affected the postural stability of the studied people, increasing the average parameters assessing balance when adopting static firing position.

Prediction of the Risk Factors of Knee Injury During Drop-Jump Landing With Core-related Measurements in Amature Basketball Players

Purpose: To evaluate the relationship between specific aspects of core stability and knee injury risk factors during drop-jump (DJ) landing.

Methods: Eighteen college-aged male amateur basketball players participated in the project. Kinetic and kinematic data for DJ tasks were collected with force plates and infrared cameras. Raw data were processed to calculate knee joint angles and joint moments during DJ landing. Different components of core stability were represented by the sit-ups in 20 s (SU), trunk extensor endurance, trunk flexion and extension range of motion, dominant extremity single-leg stance time (DLS), and dominant extremity single-leg hop distance, respectively.

Methods: Correlation and regression were used to determine the relationship between jumping-related biomechanical parameters and core stability components.

Results: SU shared significant variance with the peak moment of knee extension (PMKE, p < 0.05), the peak moment of knee abduction (PMKA, p < 0.05), and the angle of knee internal rotation at initial contact (AKRI, p < 0.05). DLS shared significant variance with the angular motion of knee internal rotation (AMKR, p < 0.05) and the AKRI (p < 0.01). SU and DLS together could explain 52% of the variance observed in the AKRI, and the result was significant.

Conclusion: Core stability’s strength and motor control aspects played an essential role in preventing knee injury during DJ landing. An integrative training program addressing core strength and motor control could be considered for coaches and athletes to prevent knee injury through core training and conditioning.

Effect of lumbopelvic control on landing mechanics and lower extremity muscles' activities in female professional athletes: implications for injury prevention

Background

Lumbopelvic control (LPC) has recently been associated with function, kinesiology, and load distribution on the limb. However, poor LPC has not been studied as a risk factor for lower limb injury in sports requiring frequent jump landings. The present study investigated the effects of LPC on landing mechanics and lower limb muscle activity in professional athletes engaged in sport requiring frequent landing.

Methods

This study was conducted on 34 professional female athletes aged 18.29 ± 3.29 years with the height and body mass of 173.5 ± 7.23 cm and 66.79 ± 13.37 kg, respectively. The landing error scoring system (LESS) and ImageJ software were used to assess landing mechanics. Wireless electromyography was also used to record the activity of the gluteus medius (GMed), rectus femoris, and semitendinosus. Lumbopelvic control was evaluated using the knee lift abdominal test, bent knee fall-out, active straight leg raising, and the PRONE test using a pressure biofeedback unit. Based on the LPC tests results, the participants were divided into two groups of proper LPC (n = 17) and poor LPC (n = 17).

Results

There were significant differences between the groups with proper and poor LPC in terms of the LESS test scores (P = 0.0001), lateral trunk flexion (P = 0.0001), knee abduction (P = 0.0001), knee flexion (P = 0.001), trunk flexion (P = 0.01), and GMed muscle activity (P = 0.03). There were no significant differences in the activity of the rectus femoris and semitendinosus muscles, and ankle dorsiflexion (P > 0.05).

Conclusions

Poor lumbopelvic control affects the kinematics and activity of the lower limb muscles, and may be a risk factor for lower limb injuries, especially of the knee.

Musculoskeletal Injuries and Their Association With Previous Concussion History: A Prospective Study of High School Volleyball and Soccer Players

BACKGROUND

Sports-related concussions may have a neurobiological recovery period that exceeds the period of clinical recovery, and one consequence of an extended neurobiological recovery may be the risk of subsequent musculoskeletal injuries. Most literature citing an increased risk of musculoskeletal injury after a sports-related concussion has been reported in populations other than adolescent athletes.

PURPOSE/HYPOTHESIS

The purpose was to prospectively determine if incidence rates of musculoskeletal injury differ between adolescent athletes with and without a previous sports-related concussion, while controlling for sex, sport, and age. A secondary aim was to determine if this relationship differs between male and female athletes of the same sport. Our hypotheses were that acute-noncontact injury rates would be higher in athletes with a previous sports-related concussion when compared with athletes without a previous sports-related concussion, and that this relationship would exist only in female athletes and not male athletes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

High school soccer and volleyball players were recruited in 2 prospective cohort studies that observed 4837 athletes during their sporting season (females, 80%; soccer, 57%; mean [SD] age, 15.6 [1.1] years). At preseason, all participants self-reported demographics and previous sports-related concussion within the past 12 months. During the sport season, team athletic trainers electronically recorded athlete exposures and injury data, including injury characteristics. Injury rates per 1000 athlete exposures and injury rate ratios (IRRs) with 95% confidence intervals were calculated. All injury rates and IRRs were adjusted for sex, age, and sport.

RESULTS

The rate of acute-noncontact lower extremity injury was 87% greater (IRR, 1.87; 95% CI, 1.29-2.74) in participants with a previous sports-related concussion versus those without one. The acute-noncontact lower extremity injury rates (IRRs) for females and males with a previous sports-related concussion were 1.76 (95% CI, 1.19-2.59) and 2.83 (95% CI, 0.85-9.50), respectively. No difference was detected in acute-contact (IRR, 0.98; 95% CI, 0.56-1.73) or overuse (IRR, 1.09; 95% CI, 0.51-2.37) lower extremity injury rates by previous sports-related concussion.

CONCLUSION

Female adolescent athletes who reported a sports-related concussion within the past 12 months were more likely to sustain an acute-noncontact lower extremity injury during their high school sports season when compared with female athletes without a previous sport-related concussion.

Reliability of Hand-Held Dynamometer for assessing Isometric Lumbar Muscles Strength in Asymptomatic Healthy Population

Objective:

To determine intra-rater and inter-rater reliability of hand-held dynamometer for assessing isometric lumbar muscle strength in asymptomatic healthy population.

Methods:

It was a cross-sectional study conducted at the department of physiotherapy, University of Lahore Teaching Hospital, Lahore, Pakistan, from July 2020 to August 2020 through non probability-purposive sampling technique. Thirty healthy subjects were tested at thirty-degree lumbar flexion and zero-degree lumbar extension positions. Two raters assessed isometric strength of lumbar flexor and extensor muscles, by a hand-held dynamometer. Strength was measured and recorded by each of the two raters and re-assessed after a week. Correlation and pairwise comparison were done between readings. ICC values were calculated for the assessment of isometric lumbar muscle strength using handheld dynamometer.

Results:

A total of 30 healthy subjects had participated with mean age of 22.84±1.21 years, height 174.33±6.83 cm, weight 68.58±5.08 kg and BMI 22.52±0.35. Findings showed an excellent intra-rater (ICC 2, k = 0.95 to 0.97) and inter-rater (ICC 2, k = 0.94 to 0.95) reliability.

Conclusions:

Hand held dynamometer demonstrated an excellent intra- and inter-rater reliability for assessment of isometric lumbar muscles strength of healthy subject at clinical setting as it is simple to use, portable and cost-effective for the precise measurement of lumbar muscles strength.

Lack of Abdominal Stability and Control as a Possible Contributor to Rectus Femoris Avulsion Fracture in the Adolescent Soccer Player: A Case Report

PURPOSE

To describe evaluation and physical therapy treatment for an athlete who is male and 13 years old with healing bilateral rectus femoris avulsion fractures.

SUMMARY OF KEY POINTS

Fractures of the anterior inferior iliac spine may be linked to poor abdominal stability in soccer athletes who are male and an adolescent. The development and use of an abdominal stability screening tool could be an efficient and effective way to determine fracture risk and guide prevention programs.

CONCLUSIONS AND RECOMMENDATIONS FOR CLINICAL PRACTICE

Following 8 weeks of conservative physical therapy treatment, the athlete met all goals and returned to pain-free soccer activities without residual impairments. Four months following discharge, he reported full participation in soccer competition without complications. This case illustrates that abdominal weakness is a potential risk factor for anterior inferior iliac spine avulsion fracture. Screening for abdominal weakness and incorporating preventative programs into training regimens is recommended to prevent anterior inferior iliac spine injuries in this population.

Trunk endurance, posterior chain flexibility, and previous history of musculoskeletal pain predict overuse low back and lower extremity injury: a prospective cohort study of 545 Navy Cadets

OBJECTIVE

To investigate predictors of low back and lower extremity musculoskeletal injury in a cohort of Naval cadets.

DESIGN

Prospective Cohort Study METHODS: 545 Naval cadets (Males, n = 394, 72%) were followed-up over eight months. Nine variables were investigated as predictors: history of musculoskeletal symptoms in the last 12 months, ankle dorsiflexion range of motion, sit and reach test, isometric hip abduction and external rotation strength, alignment during the single leg squat test, single leg hop test for distance, prone plank and side plank tests. All injuries that required medical attention were registered. Predictive associations were examined using univariable and multivariable logistic regression analyses.

RESULTS

The incidence of all injuries was 7%. Cadets who failed the 60-second plank test (OR = 3.3; 95% CI, 1.2-8.8, P = 0.04), had ≤18 cm in the sit and reach test (OR = 4.0; 95% CI, 1.4-11.2, P = 0.01), or reported pain in the last 12 months in two or more body regions (OR = 2.7; 95% CI, 1.02-7.3, P = 0.04), had greater odds of sustaining an overuse injury. No predictors were identified for acute injuries.

CONCLUSION

Decreased trunk endurance on the prone plank test, reduced posterior chain flexibility on the sit and reach test, and a history of pain reported in two or more sites in the last 12 months were predictors of overuse injuries in Naval cadets. Assessment and intervention of these modifiable risk factors may be clinically relevant in injury screening and prevention.

The role of core stability in the development of non-contact acute lower extremity injuries in an athletic population: A prospective study

OBJECTIVES

Stability of the core is associated with lower extremity functioning. Consequently, impaired core stability might play a role in developing non-contact acute lower extremity sports injuries. The objective was to investigate components of core stability as potential risk factors for acute lower extremity injuries.

DESIGN

A cohort study was set up with a follow-up and injury registration period of 1.5 years.

PARTICIPANTS

142 male and female physical education students were included.

MAIN OUTCOME MEASURES

Measures of isometric hip and core muscular strength, endurance, proprioception and neuromuscular control of the core, and postural control were taken at the start of the study. Sports-related injury occurrence was registered during follow-up.

RESULTS

27 (19%) injuries of interest occurred during follow-up. After multivariate model building, a significant predictive effect was found for side-to-side hip abduction strength asymmetry (p = .007). The hazard of developing an acute lower extremity injury increased with 6.2% with a 1 unit increase in side-to-side strength imbalance, regardless of gender.

CONCLUSION

Hip abduction strength imbalance was determined as a risk factor for the development of non-contact, acute lower extremity injuries. Normalizing hip strength imbalances might be beneficial for injury prevention. However, further research is needed to support this claim.

Modification of Pronated Foot Posture after a Program of Therapeutic Exercises

Working on the intrinsic musculature of the foot has been shown to be effective in controlling pronation. However, the potential coadjuvant effect that involving other muscle groups might have on foot posture remains unknown. The aim was, therefore, to assess whether a 9-week intrinsic and extrinsic foot and core muscle strength program influenced foot posture in pronated subjects. The participants were 36 healthy adults with pronated feet that were randomly assigned to two groups. The experimental group (n = 18) performed a strengthening exercise protocol for 9 weeks (two sessions of 40 min per week), while the control group (n = 18) did not do these exercises. After 9 weeks, the foot posture index (FPI) scores of the two groups were analyzed to detect possible changes. The FPI at the baseline was 8.0 ± 1.5. After the 9 weeks, the experimental group showed significantly reduced FPI from 8.1 ± 1.7 to 6.4 ± 2.1 (p = 0.001), while the control group had the same score as pre-intervention (FPI 8 ± 1.2, p = 1.0). The FPI scores showed no significant differences by sex. Strengthening of the intrinsic and extrinsic foot and core muscles contributed to improving foot posture in adults, reducing their FPI by 1.66 points.

The 9+ screening test score does not predict injuries in elite floorball players

We aimed to examine whether the 9+ screening test score could predict injuries in elite floorball players. Eighty-four elite floorball players participated in the study. At baseline, two physiotherapists assessed the participants using the 9+ screening test. The test score reflects strength, stability, mobility, and functional movement pattern with an emphasis on the lower body and core. Injuries that occurred the following season (2013/2014) were recorded by medical staff, coaches, and/or self-reported by the players. Overall, there was no relationship between the 9+ screening test score and injury risk (OR = 0.96 per SD lower test score, P = .84). We, therefore, conclude that the 9+ screening test is not suited for overall injury risk prediction in elite floorball players. Whether the test may be used to predict risk of certain injury types more strongly related to inadequate mobility and strength (eg, muscle ruptures or strains) warrants further investigation.