Lumbopelvic-Hip Complex Contribution During Lower Extremity Screening Tests in Elite Figure Skaters

ABSTRACT Context: Figure skating requires power and stability for take-off and landing from multi-rotational jumps and various on-ice skills. Repetitive forces may cause overuse injuries distally making lumbopelvic-hip endurance, strength, and neuromuscular control imperative. Objective: The purpose was to compare lumbopelvic-hip endurance and neuromuscular control in elite figure skaters between sex and limbs using common screening tests. Design: Cross-sectional study. Setting: U.S. Olympic and Paralympic Training Center. Participants: Forty elite figure skaters (23.2±4.3 years, 169.1±12.2 cm, 20F, 40R landing limb) performed the Y-balance test, single leg squat (SLS), single leg squat jump (SLSJ), and unilateral hip bridge endurance test. Main Outcome Measures: Normalized reach difference (% of leg length) and composite scores (((Anterior + Posteromedial + Posterolateral)/Limb length x 3) x100) were calculated for Y-balance test. Skaters held the unilateral hip bridge until failure with a maximum allotted time of 120s. Participants performed 5 SLS and SLSJ, barefooted with the contralateral limb held behind them to mimic a landing position. Both tests were scored by the number of times the patella moved medially to the first ray (medial knee displacement (MKD)). MANOVA with post-hoc independent t-tests were performed between groups and sex. Paired t-tests were used to analyze limb differences. Results: Females had a larger composite Y-balance score (R:+10.8, p=.002; L:+10.5, p=.001) and hip bridge hold time (R:+26.4 sec, p=.004; L:+28.2 sec, p=.002) on both limbs compared to males. Males held the hip bridge longer on their landing limb. During the SLS and SLSJ, 6 skaters performed worse on their non-landing limb during the SLS, and 11 skaters had no MKD with either test. Conclusions: Females performed better on the Y-balance and unilateral hip bridge tests. Increased MKD for some skaters in the SLS and SLSJ may indicate hip abductor weaknesses. Understanding proximal lumbopelvic-hip variables during take-off and landing may elucidate contributing factors to distal overuse injuries.

Gluteal muscle activation during rehabilitation exercises in female field hockey players

Background: Field hockey, a team sport played by both men and women at both recreational and professional levels, requires maintaining a forward flexed posture putting stress on the lumbar spine. Hence, it is necessary to assess the muscles supporting the lumbar spine, especially those surrounding the hip, to inform strengthening exercises for this population.Objectives: To establish the best body weight rehabilitation exercises shown to produce high muscle activation (≥ 61%MVIC – maximal voluntary isometric contraction) for both the gluteus maximus (Gmax) and medius (Gmed) muscles. Four exercises fell into this category.Method: Surface electromyography (sEMG) was used to record the muscle activation of Gmax and Gmed of four body weight rehabilitation exercises in 26 high-performance female field hockey players. The %MVIC activation data of both Gmax and Gmed were analysed using a three-way ANOVA.Results: The single-leg squat generated the highest %MVIC activation of both Gmax (125.65%MVIC) and Gmed (126.30%MVIC). The only statistically significant difference for Gmax was between the single-leg squat and plank with hip extension (p = 0.0487). No statistically significant difference was observed for Gmed between the four body weight rehabilitation exercises (p = 0.6285).Conclusion: The four exercises generated similar %MVIC activation levels. The single-leg squat produced the highest observed %MVIC of Gmax and Gmed in high-performance female field hockey players and is, therefore, recommended.Clinical implications: Implementation of the findings could result in benefits during prehabilitation, injury prevention programmes and the later stages of rehabilitation for high-performance female field hockey players.

Establishing Age- and Sex-Specific Norms for Pediatric Return-to-Sports Physical Performance Testing

Background: Graft tears and contralateral anterior cruciate ligament (ACL) tears are common in pediatric athletes after ACL reconstruction. Use of objective return-to-sports (RTS) criteria, in particular physical performance tests (PPTs), is believed to reduce the incidence of secondary injury; however, pediatric norms for these tests are unknown. Purpose: To establish a proof of concept for the creation of age- and sex-based norms for commonly used RTS PPTs in healthy pediatric athletes, allowing the creation of growth curves for clinical referencing. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 100 healthy people who were between the ages of 6 and 18 years and involved in organized sports were enrolled, with even distributions of age and sex. All participants underwent 9 common RTS PPTs: stork test, stork test on Bosu, single-leg squat, single-leg squat on Bosu, clockwise and counterclockwise quadrant hops, single-leg hop for distance, 6-m timed hop, and triple crossover hop for distance. Mean performance across limbs was calculated for each individual. Chronological age, height, weight, sex, and self-reported Pubertal Maturational Observational Scale (PMOS) score were recorded. Univariable and multivariable models were created for each PPT, assessing the importance of the recorded descriptive variables. Quantile regression was used to create growth curves for each PPT. Results: The cohort was 52% female, and the mean ± standard deviation age was 11.7 ± 3.6 years. PMOS was highly correlated with age ( r = 0.86) and was excluded from the regressions. In univariable regression, age, height, and weight were strong predictors of performance for all PPTs, whereas sex was a predictor of performance on the single-leg and triple crossover hops for distance (with males outperforming females). Height and weight were excluded from multivariable regression because of multicollinearity with age. Multivariable regression showed predictive patterns for age and sex that were identical to those shown in the univariable analysis. Given ceiling effects, quantile regression for the stork tests was not possible, but quantile regression growth curves were successfully created for the 7 remaining PPTs. Conclusion: Chronological age and sex accurately predicted performance on common RTS PPTs in pediatric patients. The growth curves presented herein could assist clinicians with benchmarking pediatric patients postoperatively against a healthy athletic cohort.

SINGLE LEG SQUAT COMPENSATIONS ASSOCIATE WITH SOFTBALL PITCHING PATHOMECHANICS IN ADOLESCENT SOFTBALL PITCHERS

Background: Softball pitchers have an eminent propensity for injury due to the high repetition and ballistic nature of the pitch. As such, trunk pathomechanics during pitching have been associated with upper extremity pain. The single leg squat (SLS) is a simple diagnostic tool used to examine LPHC and trunk stability. Research shows a lack of LPHC stability is often associated with altered pitching mechanics consequently increasing pain and injury susceptibility. Hypothesis/Purpose: The purpose of this study was to examine the relationship between trunk compensatory kinematics during the SLS and kinematics during foot contact of the windmill pitch. The authors hypothesized there would be a relationship between SLS compensations and pitch kinematics previously associated with injury. In using a simple clinical assessment such as the SLS, athletes, coaches, parents, and clinicians can identify potential risk factors that may predispose the athlete to injurious movement patterns. Methods: Fifty-five youth and high school softball pitchers (12.6±2.2 years, 160.0±11.0 cm, 60.8±15.5 kg) were recruited to participate. Kinematic data were collected at 100Hz using an electromagnetic tracking device. Participants were asked to complete a SLS on their stride leg (contralateral to their throwing arm), then throw 3 fastballs at maximal effort. Values of trunk flexion, trunk lateral flexion, and trunk rotation at peak depth of the SLS were used as the dependent variables in three separate backward elimination regression analyses. Independent variables examined at foot contact of the pitch included: trunk flexion, trunk lateral flexion, trunk rotation, center of mass, stride length, and stride knee valgus. Results: The SLS trunk rotation regression, F(1,56) = 4.980, p = .030, revealed trunk flexion significantly predicted SLS trunk rotation (SE = .068, t = 2.232, p = .030) and explained approximately 7% of variance (Adj. R2 = .066). The SLS trunk flexion regression, F(1,56) = 5.755, p = .020, revealed stride knee valgus significantly predicted SLS trunk flexion (SE = .256, t = 2.399, p = .020) and explained approximately 8% of variance (Adj. R2 = .078). Conclusion/Significance: Additional trunk rotation and trunk flexion at peak depth of the SLS indicate increased knee valgus and trunk flexion at foot contact of the pitch, both of which suggest poor LPHC stability, may increase the potential for injury. Athletes, coaches and clinicians should acknowledge the risk of poor LPHC in softball pitching and implement exercises to improve LPHC stability in effort to decrease pitching pathomechanics and associated pain.

Dynamic Radiostereometry Evaluation of 2 Different Anterior Cruciate Ligament Reconstruction Techniques During a Single-Leg Squat

Background: Lateral extra-articular tenodesis in the context of anterior cruciate ligament (ACL) reconstruction (ACLR) is performed to better control anterolateral knee instability in patients with high-grade preoperative pivot shift. However, some authors believe these procedures may cause lateral compartment overconstraint, affecting knee motion in daily life. Purpose/Hypothesis: The primary aim of the present study was to identify kinematic differences during the execution of an activity under weightbearing conditions between knees having undergone ACLR using anatomic single-bundle (SB) versus single-bundle plus lateral plasty (SBLP) techniques. The secondary aim was to compare the postoperative kinematic data with those from the same knees before ACLR and from the healthy contralateral knees in order to investigate if ACLR was able to restore physiologic knee biomechanics during squat execution. The hypotheses were that (1) the SBLP technique would allow a better restoration of internal-external (IE) knee rotation than would SB and (2) regardless of the technique, ACLR would not fully restore physiologic knee biomechanics. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: In total, 32 patients (42 knees) were included in the study. Patients were asked to perform a single-leg squat before surgery (ACL-injured group, n = 32; healthy contralateral group, n = 10) and at minimum 18-month follow-up after ACLR (SB group, n = 9; SBLP group, n = 18). Knee motion was determined using a validated model-based tracking process that matched patient-specific magnetic resonance imaging bone models to dynamic biplane radiographic images under the principles of roentgen stereophotogrammetric analysis. Data processing was performed using specific software. The authors compared IE and varus-valgus rotations and anterior-posterior and medial-lateral translations among the groups. Results: The mean follow-up period was 21.7 ± 4.5 months. No kinematic differences were found between the SB and SBLP groups ( P > .05). A more medial tibial position ( P < .05) of the ACL-injured group was reported during the entire motor task and persisted after ACLR in both the SB and the SBLP groups. Differences in IE and varus-valgus rotations were found between the ACL-injured and healthy groups. Conclusion: There were no relevant kinematic differences between SBLP and anatomic SB ACLR during the execution of a single-leg squat. Regardless of the surgical technique, ACLR failed in restoring knee biomechanics. Registration: NCT02323386 ( ClinicalTrials.gov identifier).

Visual assessment of movement quality: a study on intra- and interrater reliability of a multi-segmental single leg squat test

Background The Single Leg Squat test (SLS) is a common tool used in clinical examination to set and evaluate rehabilitation goals, but there is not one established SLS test used in the clinic. Based on previous scientific findings on the reliability of the SLS test and with a methodological rigorous setup, the aim of the present study was to investigate the intra- and interrater reliability of a standardised multi-segmental SLS test. Methods We performed a study of measurement properties to investigate the intra- and interrater reliability of a standardised multi-segmental SLS test including the assessment of the foot, knee, pelvis, and trunk. Novice and experienced physiotherapists rated 65 video recorded SLS tests from 34 test persons. We followed the Quality Appraisal for Reliability Studies checklist. Results Regardless of the raters experience, the interrater reliability varied between “moderate” for the knee variable (ĸ = 0.41, 95% CI 0.10–0.72) and “almost perfect” for the foot (ĸ = 1.00, 95% CI 1.00–1.00). The intrarater reliability varied between “slight” (pelvic variable; ĸ = 0.17, 95% CI -0.22-0.55) to “almost perfect” (foot variable; ĸ = 1.00, 95% CI 1.00–1.00; trunk variable; ĸ = 0.82, 95% CI 0.66–0.97). A generalised kappa coefficient including the values from all raters and segments reached “moderate” interrater reliability (ĸ = 0.52, 95% CI 0.43–0.61), the corresponding value for the intrarater reliability reached “almost perfect” (ĸ = 0.82, 95% CI 0.77–0.86). Conclusions The present study shows a “moderate” interrater reliability and an “almost perfect” intrarater reliability for the variable all segments regardless of the raters experience. Thus, we conclude that the proposed standardised multi-segmental SLS test is reliable enough to be used in an active population.

Hip and ankle strength and range of motion in female soccer players with dynamic knee valgus

BACKGROUND: Dynamic knee valgus (DKV) is a known risk factor for acute and chronic knee injuries and is more frequently diagnosed in females. A real-time single-leg squat test (SLST) could screen for DKV to prevent injuries. OBJECTIVE: To compare the differences in lower extremity strength and range of motion (ROM) in female soccer athletes with and without DKV during an SLST. METHODS: Eighteen subjects with DKV (DKV group) and 18 subjects without DKV (control group) during a single-leg squat were included. Hip strength (flexion, extension, abduction, adduction, internal rotation, and external rotation) was measured with a hand-held dynamometer. Hip ROM (internal and external rotation), and ankle ROM (dorsiflexion with the knee flexed and extended) were measured. Independent t-test was used to compare the averages of the groups. RESULTS: There were significant differences in hip abduction to adduction strength ratio (DKV: 1.48 ± 0.3, control: 1.22 ± 0.26, p< 0.01) and ankle dorsiflexion with knee flexed (DKV: 17.22 ± 6.82, control: 21.22 ± 4.55, p< 0.05) and extended (DKV: 10.14 ± 4.23, control: 14.75 ± 3.40, p< 0.001) between the groups. CONCLUSION: The hip abduction to adduction strength ratio and gastrocnemius and soleus flexibility may be associated factors in dynamic knee valgus and therefore should be assessed and treated, if indicated, as a possible preventive measure in female athletes with this variation.