Hip external rotation isometric torque for soccer,basketball, and volleyball athletes: normative data and asymmetry index

BackgroundDeficits in strength of the hip external rotators (ER) affect trunk, hip, and knee movement patterns, potentially contributing to injury in athletes.ObjectivesTo provide normative data on isometric torque for hip ER in athletes of three distinct sports and to determine if isometric torque for the hip ER and torque asymmetry between legs differ among sports and between sexes.MethodsBasketball, soccer, and volleyball athletes (n=451) were evaluated. Hip ER torque was quantified bilaterally with athletes in prone and 90° of knee flexion using a hand-held dynamometer.ResultsData are expressed as mean and 95% confidence interval. Hip ER torque values in Nm/kg for the dominant and non-dominant limbs were, respectively, 0.46 (0.44, 0.48) and 0.42 (0.40, 0.44) for male soccer athletes; 0.35 (0.32, 0.37) and 0.27 (0.25, 0.29) for male basketball athletes; and 0.37 (0.34, 0.39) and 0.35 (0.32, 0.37) for male volleyball athletes. Hip ER torque in Nm/kg for the female volleyball athletes was 0.29 (0.26, 0.33) for the dominant and 0.29 (0.25, 0.32) for the non-dominant limb. The Limb Symmetry Index for male soccer, basketball, and volleyball players was, respectively, 94% (91, 97), 81% (75, 87), and 95% (91, 99). For female volleyball players the Limb Asymmetry Index was 102% (95, 108). Male volleyball athletes showed higher torque values than female volleyball athletes.ConclusionsThis study reported normative values for hip ER isometric torque of youth athletes. Clinicians can use the reported data as reference to identify torque deficits in athletes of the three reported sports.     

Application of Shear-Wave Elastography in the Evaluation of Hamstring Stiffness in Young Basketball Athletes

BackgroundPrevious literature has postulated a relationship between greater hamstring stiffness and a higher risk of sustaining injury. Shear wave elastography (SWE) presents a relatively new means for non-invasive evaluation of soft tissue elasticity pre- and post- injury or intervention.Purpose1. To establish baseline hamstring stiffness measures for young competitive athletes and (2) determine effect of targeted neuromuscular training (TNMT) on shear wave stiffness of the hamstring.Study DesignUn-blinded, prospective, non-randomized, cohort study.MethodsSix-hundred forty-two lower extremities from 321 high school and collegiate basketball athletes (177 F: 139 M) were examined for hamstring stiffness prior to the start of their competitive basketball season. Teams were cluster assigned to either the control or intervention (TNMT) group. Subjects in the control group underwent regular season activities as directed, with no influence from the research team. For the TNMT group, the research team introduced a hamstring targeted dynamic warm-up program as an intervention focused on activating the hamstring musculature.ResultsCollegiate status was significant to hamstring stiffness for both sexes (p ≤ 0.02), but hamstring stiffness did not correlate to age or sex (r² ≤ 0.08). Intervention was a significant factor to hamstring stiffness when the hip was positioned in extension (p ≤ 0.01), but not in deeper flexion (p = 0.12). This effect was sex-specific as TNMT influenced hamstring stiffness in females (p = 0.03), but not in males (p ≥ 0.13). Control athletes suffered three HAM injuries; TNMT athletes suffered 0 hamstring injuries.ConclusionHigher SWE measurements correlated with increased risk of injury, male sex, and collegiate athletics. TNMT intervention can lessen muscle stiffness which may reduce relate to injury incidence. Intervention effectiveness may be sex specific.Level of EvidenceII     

NORMATIVE VALUES OF ECCENTRIC HIP ABDUCTION STRENGTH IN NOVICE RUNNERS: AN EQUATION ADJUSTING FOR AGE AND GENDER

Purpose:

Low eccentric strength of the hip abductors, might increase the risk of patellofemoral pain syndrome and iliotibial band syndrome in runners. No normative values for maximal eccentric hip abduction strength have been established. Therefore the purpose of this study was to establish normative values of maximal eccentric hip abduction strength in novice runners.

Methods:

Novice healthy runners (n = 831) were recruited through advertisements at a hospital and a university. Maximal eccentric hip abduction strength was measured with a hand–held dynamometer. The demographic variables associated with maximal eccentric hip abduction strength from a univariate analysis were included in a multivariate linear regression model. Based on the results from the regression model, a regression equation for normative hip abduction strength is presented.

Results:

A significant difference in maximal eccentric hip abduction strength was found between males and females: 1.62 ± 0.38 Nm/kg (SD) for males versus 1.41 ± 0.33 Nm/kg (SD) for females (p < 0.001). Age was associated with maximal eccentric hip abduction strength: per one year increase in age a ‐0.0045 ± 0.0013 Nm/kg (SD) decrease in strength was found, p < 0.001. Normative values were identified using a regression equation adjusting for age and gender. Based on this, the equation to calculate normative values for relative eccentric hip abduction strength became: (1.600 + (age * ‐0.005) + (gender (1 = male / 0 = female) * 0.215) ± 1 or 2 * 0.354) Nm/kg.

Conclusion:

Normative values for maximal eccentric hip abduction strength in novice runners can be calculated by taking into account the differences in strength across genders and the decline in strength that occurs with increasing age. Age and gender were associated with maximal eccentric hip abduction strength in novice runners, and these variables should be taken into account when evaluating eccentric hip abduction strength in this group of athletes.

Level of Evidence:

2A     

Twelve-Week Quadriceps Strength as A Predictor of Quadriceps Strength At Time Of Return To Sport Testing Following Bone-Patellar Tendon-Bone Autograft Anterior Cruciate Ligament Reconstruction

BackgroundRestoration of quadriceps strength following anterior cruciate ligament reconstruction (ACL-R) continues to challenge both patients and clinicians. Failure to adequately restore quadriceps strength has been linked to decreased patients’ self-reported outcomes and an increased risk for re-injury. Early identification of quadriceps strength deficits may assist in tailoring early interventions to better address impairments.PurposeThe purpose of this study was to assess the relationship between early (12 weeks following ACL-R) isokinetic peak torque and isokinetic peak torque at time of return to sport (RTS) testing.Study DesignCohort StudyMethodsA total of 120 participants (males = 55; females =65) were enrolled in the study (age = 16.1±1.4 yrs; height = 1.72±10.5 m; mass = 70.7±16.3 kg). All participants were level 1 or 2 cutting and pivoting sport athletes who underwent a primary bone-patellar tendon-bone autograft ACL-R. Participants were tested at two time points: 12 weeks following surgery and again at time of RTS testing. A linear regression model was carried out to investigate the relationship between age, sex, and isokinetic peak torque at 12 weeks following ACL-R and isokinetic peak torque at time of RTS testing.ResultsWhen 12-week isokinetic peak torque was entered first for the hierarchy regression analysis, this factor was predictive of the peak torque at the time of RTS testing, F(1, 118) = 105.6, p < 0.001, R² = 0.472, indicating that the 12-week quadriceps strength accounted for 47% of the variance in the quadriceps strength at the time of RTS testing. When age and sex were added in the regression analysis, both factors only added 0.8% of variance for the quadriceps strength at the time of RTS testing.ConclusionIsokinetic peak torque at 12 weeks following surgery was shown to be a significantly strong predictor (47%) for isokinetic quadriceps strength recovery at time of RTS. This finding underscores the importance of early restoration of quadriceps strength and that while non-modifiable factors such as sex and age are important, early restoration of quadriceps strength most strongly influences late stage quadriceps strength.Level of Evidence3     

Knee motion and muscle activation patterns are altered in hip osteoarthritis: The effect of severity on walking mechanics

BackgroundKnee function is impaired in individuals with moderate hip osteoarthritis. How this extends to those undergoing total hip arthroplasty is unknown despite the common requirement for knee arthroplasty in this population. The study purpose was to determine whether sagittal plane knee joint movements and quadriceps and hamstring activation patterns differ between individuals with either moderate or severe unilateral hip osteoarthritis, and between ipsilateral and contralateral knees.Methods20 individuals with moderate osteoarthritis and 20 with severe osteoarthritis were recruited. Sagittal knee motion and surface electromyograms from the hamstrings and quadriceps were collected during treadmill walking at a self-selected speed. Principal component analysis captured amplitude and temporal sagittal plane motion and EMG waveform features. Student's t-tests and Analysis of Variance determined between group differences and within/between group leg differences.FindingsThe severe groups' contralateral knee was in greater flexion at initial contact and demonstrated a movement profile of a longer stance phase (p < 0.001). The severe group had reduced sagittal plane knee motion (p < 0.0001); more so in the ipsilateral knee (p < 0.0001). The severe group had greater hamstring (p = 0.009) and quadriceps activation (p < 0.001) overall, specifically mid-stance quadriceps bilaterally (p = 0.002). Ipsilateral sagittal plane knee motion was reduced in both groups. Compared with those with moderate osteoarthritis, individuals with severe osteoarthritis walk with reduced sagittal plane knee motion bilaterally, suggesting prolonged contralateral stance, and elevated mid-stance hamstring and quadriceps activation.InterpretationAltered kinematics and muscle activity could contribute to a greater mechanical demand on the contralateral knee in those with more severe hip osteoarthritis.     

Medio-Lateral Hamstring Muscle Activity in Unilateral vs. Bilateral Strength Exercises in Female Team Handball Players – A Cross-Sectional Study

BackgroundReduced activation of the hamstring muscles and specifically the medial semitendinosus muscle (ST) has been shown to be a risk factor for non-contact anterior cruciate ligament (ACL) injury. Specific hamstring strength exercises may show high ST activity, however the effect of unilateral vs. bilateral exercise execution on ST activation remains unknown.PurposeTo investigate selected lower limb strengthening exercises performed either unilaterally or bilaterally to identify 1) which exercise elicited the highest hamstring activation, 2) which exercise elicited the highest ST activation, and 3) to examine if unilateral exercise execution altered the medio-lateral hamstring activation pattern. Furthermore, the kinematic characteristics of each specific exercise and execution modality were determined to reveal possible causes for differences in medio-lateral hamstring activation between the different exercise conditions.Study designCross-sectional study.MethodsSingle-session repeated measures were obtained in a randomized manner. Twenty-three female elite team handball players were recruited. Hamstring electromyographic (EMG) activity and 3D kinematics were obtained during selected lower limb exercises (hip thrust, kettlebell swing, Romanian deadlift). Hamstring EMG activity, normalized to maximal voluntary contraction (MVC) (nEMG), and inter-muscular activation difference between the ST and lateral hamstring biceps femoris (BF) were compared across exercises using two-way repeated measures ANOVA.ResultsBilateral hip thrust demonstrated highest overall hamstring activity (68.9±16.6 %). Kettlebell swing (Δ13%-point, p<0.01) and Romanian deadlift (Δ20-24%-point, p<0.01) demonstrated greater ST-BF activation differences (Δ=ST-BF) in favor of ST compared to hip thrust (Δ2-7%). Positive correlations were observed between knee joint angle and ST activity in kettlebell swing and deadlift.ConclusionKettlebell swing, deadlift and hip thrust all produced high activation of the hamstring muscles. Kettlebell swing and both deadlift exercises were superior in activating ST over BF, favoring these exercises in the prevention of non-contact ACL injury in female athletes, which should be evaluated in future intervention studies.Level of evidence3     

The Neuromuscular Effects of the Copenhagen Adductor Exercise: A Systematic Review

BackgroundGroin strains are one of the most common time-loss injuries in athletes. The Copenhagen Adductor Exercise (CAE) eccentrically strengthens the adductors and may function to prevent adductor strains, similar to the eccentric mechanism in which the Nordic Hamstrings exercise acts to prevent hamstring strains.ObjectiveThe purpose of this study was to systematically review the literature on the CAE and its effects on adductor muscle strength and muscle activity in athletes.Study DesignSystematic ReviewMethodsA systematic search of the literature was performed in the following databases: Pubmed; Medline (EBSCO); Sportdiscus; Scopus; Web of Science; CINAHL; Proquest; Cochrane Library; Physiotherapy Evidence Database (PEDro). Inclusion criteria consisted of 1) implements CAE, 2) includes athletes of any age participating in at least one sport, 3) study type is a cohort study or randomized control trial. Studies were excluded if they were not written in English or did not measure strength as an outcome. Data were extracted on eccentric hip adductor strength (EHAD), eccentric hip abductor strength (EHAB), EHAD:EHAB ratio, and electromyography (EMG) activity of the adductor muscles. Quality assessment was performed on all included studies using Quality Assessment Tool for Quantitative Studies.ResultsFive articles were identified for inclusion, four of which received a strong rating, and one a moderate rating on the Quality Assessment Tool for Quantitative Studies. The CAE significantly increased EHAD in four of the four studies that examined it; significantly increased EHAB and EHAD:EHAB in three of the three studies that examined them, and increased the EMG activity of the adductors in the dominant leg 108%.ConclusionOverall, the CAE increases EHAD, EHAB, EHAD:EHAB, and EMG activity in the hip adductors in male soccer players. The increase in strength may reduce adductor muscle injuries, although more research needs to be done in this area to identify a clear relationship between the CAE and groin injury prevention.Level of Evidence1b     

The Effects of Soft Tissue Flossing on Hamstring Range of Motion and Lower Extremity Power

BackgroundFlossing includes wrapping a specialized latex band around a muscle group providing compression, partially occluding blood flow, followed by performing exercises. This is hypothesized to improve flexibility by dissipating myofascial adhesions; however, research is lacking.ObjectiveTo determine the effect of the application of a floss band to the thigh on hamstring flexibility and lower extremity power.DesignCrossover StudySettingExercise Physiology Laboratory.ParticipantsTwenty-one recreationally active individuals (8 male, 13 female; age = 22.62±2.99 years; height = 171.52±9.08 cm; mass = 73.57±11.37 kg).MethodsThree counterbalanced interventions were studied during body weight squats, lunges, and hamstring curls (without resistance): floss, sham, and control. The floss treatment included wrapping the Rogue Wide Voodoo Floss Band™ from the proximal knee to the gluteal fold at a pressure of 140 to 200 mmHg. The sham treatment included wrapping the same band in the same location with less pressure (10 to 40 mmHg) while the control treatment did not include floss band application. Hip flexion range of motion, via the straight leg raise, and power (single-leg vertical jump) were compared from pre-test to post-test using a 3x2 repeated measures ANOVA.ResultsThere was a significant interaction between time and session for hamstring flexibility (F_(2,40)=17.54, p<0.001, η²=0.47). Post hoc tests showed significant differences between pre- (86.14±8.06 degrees) and post-test (90.81±7.69 degrees) for the floss session (p<0.001, Mean Difference=4.67, CI₉₅=3.35-5.98) and between pre- (87.67±7.51 degrees) and post-test (89.86±7.88 degrees) for the sham session (p=0.001, Mean Difference=2.19, CI₉₅=0.98-3.40). There were no significant interactions for jump power (F_(2,40)=1.82, P=0.18, η²=0.08, 1-β=0.36).ConclusionsFlossing treatment increased hamstring flexibility more than the sham session without affecting lower body power. Flossing could be beneficial when treatment or performance preparation goals are increased flexibility without decreased power. Future studies should continue to examine the clinical effectiveness of flossing on an injured population.     

Foam rolling improvements in passive hip flexion last up to 60-minutes in ice hockey players

BackgroundIce hockey players often lack hip mobility which may be attributed to excessive time spent in a flexed position during competition and the intensive use of hip external rotators and extensors. Previous investigations demonstrate that foam rolling increases range-of-motion in healthy populations. It is unclear whether such benefits occur in athletes with chronic hip tightness. Further, athletes often perform pre-competition warm-up up to 60-min prior to a game, therefore we investigated the retention of the effects of foam rolling. The purpose of this study was to analyze the effects of foam rolling the anterior and posterior aspects of the thigh on passive hip flexion in ice hockey players, up to 60-min post-rolling.MethodsSixteen amateur ice hockey players (8 ♀, 22 ± 2 years, 25.1 ± 3.5 kg m⁻²) warmed up for 5-min then performed 2, 1-min bouts of foam rolling using a high density multi-rigid roller on the quadriceps and hamstrings, with 1-min break between sets. Passive hip flexion was measured before and immediately after rolling, 10-min, 30 and 60-min post-rolling using the Coach's Eye application during a passive straight leg raise.ResultsCompared to baseline, passive hip flexion was greater immediately after foam rolling (p < 0.01), 10 min (p = 0.05), 30 (p < 0.01) and 60-min post-rolling (p < 0.01).ConclusionsRegardless of measurement time point, significant increases in passive hip flexion occurred up to 60-min compared to baseline. Incorporation of foam rolling into pre-competition warm-ups may be beneficial when increases in hip mobility are warranted, up to 1-h before competition.     

Neuromuscular joint function in knee osteoarthritis: A systematic review and meta-analysis

BackgroundNeuromuscular alterations are common in people with knee osteoarthritis (KOA). A comprehensive understanding of these alterations is important to enable targeted rehabilitation strategies.ObjectivesThis systematic review and meta-analysis aimed to comprehensively understand the neuromuscular alterations around the knee joint in people with KOA.MethodsModerate- and high-quality studies based on a modified version of the Downs and Black checklist, comparing neuromuscular function of peri?articular muscles between people with KOA and controls were retrieved from five databases from inception to October 2020. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and torque-related outcomes. Data were pooled according to structural KOA severity with sensitivity analysis based on sex. Evidence levels are presented in evidence gap maps.ResultsA total of 7 high-quality and 22 moderate-quality studies were retained (1146 people with KOA and 1353 age- and sex-matched controls). Studies demonstrated quadriceps and hamstring strength deficits and increased hamstring-to-quadriceps strength ratios across KOA severities. Women presented lower quadriceps strength at early KOA (very limited evidence) and lower voluntary activation at end stage KOA (very limited evidence) as compared with controls, whereas men did not (moderate evidence). People with KOA also demonstrated lower quadriceps force control ability with no change in rapid force production (very limited evidence). Voluntary activation deficits for quadriceps were evident (moderate evidence), with no change in quadriceps cortical excitability (very limited evidence) or soleus spinal reflexes (very limited evidence). No muscle size change was demonstrated except for the vastus medialis (limited evidence). Evidence gaps were found for neural and torque-related measures and differences in hamstring, gastrocnemius, soleus, and popliteus.ConclusionsNeuromuscular deficits are evident across different structural KOA severities and are seen in muscle strength, voluntary activation, muscle size, and force control ability. Women may exhibit these alterations to a greater extent than men.Prospero registration numberCRD42019160845.     

Reliability of the Modified CKCUEST and correlation with shoulder strength in adolescent basketball and volleyball players

BackgroundPhysical performance tests provide a more complete picture of the functional status of the athlete's upper extremity.ObjectivesThe primary purpose was to evaluate the reliability of the Modified Closed Kinetic Chain Upper Extremity Stability Test (MCKCUEST) in adolescent volleyball and basketball players. The secondary objective was to evaluate the relationship between the MCKCUEST and shoulder rotation isometric strength in this population.MethodsSeventy-three healthy basketball (n = 39) and volleyball (n = 34) players participated to establish the reliability and correlations of the MCKCUEST. We used a two-session measurement design to evaluate the reliability of the MCKCUEST. Shoulder rotation isometric strength was performed to determine relationships with the MCKCUEST.ResultsThe intraclass correlation coefficients (ICC_2,1) for intra-session reliability of the MCKCUEST ranged from 0.86 to 0.89, and the between days test–retest reliability (ICC_3,1) was 0.93. The standard error of measurement (1 touch) and the minimal detectable change (3 touches) showed clinically acceptable absolute reliability values. A weak correlation was found between the MCKCUEST power score and shoulder rotation isometric strength (r values between 0.3 and 0.4).ConclusionsResults demonstrated good to excellent relative reliability and clinically acceptable absolute reliability values for the MCKCUEST on adolescent basketball and volleyball athletes. Performances on the MCKCUEST were weakly associated with shoulder rotation strength.     

Influence of lower limb torque,range of motion,and foot alignment in patellar rotation (Arno angle) in athletes

BackgroundAlterations of frontal plane patellar alignment could be related to lower limb disorders. Clinical assessment must be able to identify the influence of non-local factors in patellar alignment.ObjectiveTo identify the influence of lower limb torque, range of motion (ROM), and foot alignment on patellar rotation in healthy athletes.MethodsThis cross-sectional study was performed with 232 healthy basketball and volleyball elite athletes. Participants were assessed in preseason for: patellar medial and lateral rotation (Arno angle), passive hip internal rotation (IR) ROM, iliotibial band flexibility, hip abductors and external rotators (ER) torque, shank-forefoot alignment (SFA), and ankle dorsiflexion ROM. Hierarchical multiple linear regression was performed to identify if these variables and sex, age, and body mass could be associated with patellar rotation in a standing position.ResultsHip ER isometric torque explained a small part (10%) of the variance of the Arno angle in healthy athletes (R² change=0.10; unstandardized ß=11.74 (95% CI 6.82, 16.65); Standardized Coefficient Beta=0.32) and sex explained 2% of its variance (R² change=0.02; unstandardized ß= 2.42 (95% CI 0.32, 4.52); Standardized Coefficient Beta=0.15). After controlling for sex, hip ER torque explained 9% of Arno angle variance (R² change=0.09; unstandardized ß= 11.09 (95% CI 6.43, 15.76; Standardized Coefficient Beta=0.31). The other variables were not associated with patellar rotation.ConclusionsHip ER torque may influence patellar rotation in different directions (medial or lateral rotation). Possible mechanisms that explain the contribution of higher and lower hip ER torque in lateral and medial patellar rotation, respectively, are discussed.     

Decreased passive muscle stiffness of vastus medialis is associated with poorer quadriceps strength and knee function after anterior cruciate ligament reconstruction

BackgroundMuscle deficits of the quadriceps and hamstrings are common after anterior cruciate ligament reconstruction, and increase the risk of knee reinjury. Muscle stiffness is an important factor for dynamic joint stability. However, the changes in quadriceps and hamstring muscle stiffness and its influence after anterior cruciate ligament reconstruction remain unclear.MethodTwenty-five male subjects with anterior cruciate ligament reconstruction and twenty-one matched healthy subjects participated in this study. The passive muscle stiffness of the quadriceps and hamstrings was assessed by shear modulus using ultrasound shear wave elastography. The isokinetic muscle strengths of the quadriceps and hamstrings were tested. Knee function was evaluated by the International Knee Documentation Committee and Lysholm score. Muscle stiffness was compared between limbs via non-parametric tests. Correlation analysis was used to detect the relationship between muscle stiffness, isokinetic muscle strength and knee functional scores.FindingsThe involved limb exhibited significantly decreased shear modulus in the vastus medialis compared to the dominant limbs(z = −3.585;P = 0.001;ES = 1.13) and non-dominant limbs(z = −3.551;P = 0.002;ES = 1.24) of healthy controls. The shear modulus of ST was also significantly lower in the involved limb when compared with the contralateral limbs(z = −3.996;P < 0.001;ES = 1.33), dominant limbs(z = −4.477;P < 0.001;ES = 1.65) and non-dominant limbs(z = −4.234;P = 0.001;ES = 1.43) of healthy controls. The shear modulus of the vastus medialis was associated with quadriceps peak torque at 60°/s(r = 0.470; p < 0.001) and knee functional score(r = 0.459; p = 0.021).InterpretationThe passive muscle stiffness of the vastus medialis decreased after anterior cruciate ligament reconstruction, which is associated with poorer quadriceps strength and knee function. The effect of modulation of muscle stiffness on improving knee function warrants future investigation.     

Knee extensor muscles strength indicates global lower-limb strength in individuals who have suffered a stroke: A cross-sectional study

ObjectivesThis study had three aims: (1) to evaluate the relationships between the paretic knee extensor muscle strength and global lower-limb strength in individuals who had suffered a sub-acute/chronic stroke, (2) to determine whether global lower-limb strength, sex, body mass index, or age could predict knee extensor muscle strength, and 3) to investigate whether the results obtained via a Modified Sphygmomanometer Test (MST) would be similar to those obtained using a hand-held dynamometer.MethodsThis was a cross-sectional study, performed at a research laboratory, at participants’ homes, or at outpatient clinics. Forty-two individuals with a sub-acute stroke and 45 individuals with a chronic stroke participated. Maximum isometric strength of the paretic lower-limb muscles (i.e. hip, knee, and ankle flexors/extensors, hip abductors) was measured using the MST and a hand-held dynamometer.ResultsSignificant and high correlation coefficients were found between knee extensor muscle strength and global lower-limb strength as measured by the combined strength values of 6 lower limb muscle groups in individuals with sub-acute (0.81 ≤ r ≤ 0.88; p < 0.05) and chronic (0.82 ≤ r ≤ 0.85; p < 0.05) stroke. Step-wise multiple regression analysis revealed that only global lower-limb strength was retained in the model and accounted for 66–78% and 67–72% (p < 0.001) of the variance in knee extensor muscle strength at the sub-acute and chronic phases post-stroke, respectively. The results obtained via the MST were similar to those obtained using the hand-held dynamometer.ConclusionParetic knee extensor muscles strength, assessed using a MST or a hand-held dynamometer, indicates global lower-limb strength in individuals with a sub-acute or chronic stroke.     

Effect of Whole-Body Vibration Exercise on Power Profile and Bone Mineral Density in Postmenopausal Women With Osteoporosis: A Randomized Controlled Trial

ObjectiveThe purpose of this study was to investigate the effect of whole-body vibration (WBV) on muscle work and bone mineral density (BMD) of the lumbar vertebrae and femur in postmenopausal women.MethodsForty-three postmenopausal women with low BMD were randomly assigned to WBV and control groups. Both groups received calcium and vitamin D supplementations once daily, while the WBV group additionally received WBV exercise (twice/wk) for 24 successive weeks. Qualisys gait analysis system was used to measure hip power generation by hip extensors (H1S) and flexors (H3S), hip power absorption by hip flexors (H2S), knee power absorption by quadriceps during loading response (K1S) and preswing (K3S), knee power absorption by hamstring (K4S), knee power generation by quadriceps (K2S), ankle power absorption by dorsiflexors (A1S) and plantar flexors (A2S), and ankle power generation by plantar flexors (A3S). Also, dual-energy X-ray absorptiometry was used to measure BMD of the lumbar vertebrae and femur before and after the intervention.ResultsThere were significant increases (P < .05) in the hip muscle work (H1S, H2S, and H3S), knee muscle work (K1S, K2S, K3S, and K4S), ankle muscle work (A1S, A2S, and A3S) during gait, and BMD of the lumbar vertebrae and femur of the WBV group. However, there were no significant changes (P > .05) in the control group. The posttreatment values of the hip, knee, and ankle muscle work and BMD of the WBV group were significantly (P < .05) higher than the posttreatment values of the control group.ConclusionWhole-body vibration training improved the leg muscle work and lumbar and femoral BMD in postmenopausal women with low BMD.     

Quadriceps Strength following Anterior Cruciate Ligament Reconstruction: Normative Values based on Sex,Graft Type and Meniscal Status at 3, 6 & 9 Months

BackgroundHigher postoperative quadriceps function has been positively associated with surgical outcomes after anterior cruciate ligament reconstruction (ACLR). However, the impact of autograft harvest and/or a concomitant meniscal procedure on the recovery of quadriceps strength is not well defined.PurposeTo describe postoperative recovery of quadriceps strength following ACLR related to autograft selection, meniscal status, and sex.Study DesignRetrospective Cohort.MethodsOne hundred and twenty-five participants who underwent ACLR with either a hamstring tendon (HT), bone-patellar tendon-bone (BPTB) or quadriceps tendon (QT) autograft were included. At postoperative months 3, 6 and 9, each participant completed an isometric quadriceps strength testing protocol at 90-degrees of knee flexion. Participants’ quadriceps average peak torque (Q-AvgPKT), average peak torque relative to body weight (Q-RPKT), and calculated limb symmetry index (Q-LSI) were collected and used for data analysis. Patients were placed in groups based on sex, graft type, and whether they had a concomitant meniscal procedure at the time of ACLR. At each time point, One-way ANOVAs, independent samples t-test and chi-square analyses were used to test for any between-group differences in strength outcomes.ResultsAt three months after ACLR, Q-RPKT was significantly higher in those with the HT compared to the QT. At all time points, males had significantly greater Q-RPKT than females and HT Q-LSI was significantly higher than BPTB and QT. A concomitant meniscal procedure at the time of ACLR did not significantly affect Q-LSI or Q-RPKT at any testing point.ConclusionThis study provides outcomes that are procedure specific as well as highlights the objective progression of quadriceps strength after ACLR. This information may help better-define the normal recovery of function, as well as guide rehabilitation strategies after ACLR.Level of Evidence3     

Musculoskeletal profile of male collegiate soccer players

Twenty-five collegiate soccer players were evaluated for lower extremity flexibility and muscle strength at the end of preseason training and before the onset of the collegiate soccer season on two successive seasons. The purpose of the evaluation was to determine whether symmetry was present in their legs and whether deficits in flexibility or strength would affect the susceptibility to hamstring or groin muscle strain injuries. The mean (+/- SE) flexibility of the dominant leg for hip abduction was 41 degrees +/- 1.2 degree; for hip flexion, 76 degrees +/- 1.9 degree; for hip extension, 174 degrees +/- 0.7 degree; and for ankle dorsiflexion, 33 degrees +/- 1.3 degree. The mean (+/- SE) isokinetic torque of the dominant leg (tested at 30 degrees per second) for knee extension was 214 +/- 8 newton meters and for flexion was 128 +/- 4 newton meters, while isometric strength for hip flexion was 315 +/- 8 newtons and for ankle plantar flexion was 1721 +/- 58 newtons. No significant differences were found between the dominant and nondominant legs in flexibility or strength. During this study no hamstring or groin strain injuries occurred. The lack of leg muscle strain injuries appeared to be directly related to the initiation of a controlled warmup and stretching program and underlines the importance of this in injury prevention. Interestingly, more than 50% (13 of 25) of the players were found to have significant deficits in one or more specific muscle groups. Two athletes sustained low back strain injuries and one athlete had a knee sprain injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage

BackgroundIntense physical activity can result in exercise-induced muscle damage, delayed-onset muscle soreness, and decrements in performance. Phototherapy (PhT), sometimes referred to as photobiomodulation or low-level laser therapy, may enhance recovery from vigorous exercise.PurposeThe purpose of this study was to assess the influence of phototherapy on functional movements (vertical jump, agility), and perceptions of muscle soreness following exercise-induced muscle damage caused by high volume sprinting and decelerations.MethodsIn a between-group design, 33 participants performed 40x15m sprints, a protocol intended to cause muscle damage. Immediately following sprinting and in the four days following, vertical jump and agility were assessed, as well as calf, hamstring, quadriceps, and overall perceptions of soreness. Sixteen subjects (age 20.6±1.6 yrs; BMI 25.8±4.6 kg.m-2) received PhT prior to testing each day, while 17 (age 20.8±1.3 yrs; BMI 26.2±4.5 kg.m-2) received sham PhT and served as a control (CON). Measurements were recorded during five days of recovery from the repeated sprint protocol, then compared to those recorded during three baseline days of familiarization. Area under the curve was calculated by summing all five scores, and comparing those values by condition via a two-tailed unpaired t-test for normally distributed data, and a two-tailed Mann-Whitney U test for nonparametric data (alpha level = 0.05).ResultsCalf soreness was lower in PhT compared to CON (p = 0.02), but no other significant differences were observed between groups for vertical jump, agility, quadriceps, hamstring, and overall soreness (p > 0.05).DiscussionPhototherapy may attenuate soreness in some muscle groups following exercise-induced muscle damage, but may not enhance recovery after explosive, short-duration activities.ConclusionPhototherapy may not be a useful recovery tool for those participating in explosive, short-duration activities.Level of evidence2c     

Key characteristics of low back pain and disability in college-aged adults: a pilot study

Handrakis JP, Friel K, Hoeffner F, Akinkunle O, Genova V, Isakov E, Mathew J, Vitulli F. Key characteristics of low back pain and disability in college-aged adults: a pilot study.ObjectiveTo identify which factors commonly associated with low back pain (LBP) and disability differ between college-aged persons with LBP and with no or minimal LBP.DesignClinical measurement, observational study. Subjects were assessed for LBP with the visual analog scale (VAS) and for disability from LBP using the Oswestry Disability Index (ODI). Subjects were measured for variables commonly associated with LBP and were grouped by both VAS (minimum [min]/no pain, pain) and ODI (no disability, disability) scores.SettingCollege campus at a university.ParticipantsA convenience sample (N=84) of English-speaking students (34 men, 50 women) between 18 and 30 years of age.InterventionsNot applicable.Main Outcome MeasuresSports activity (sports activity score of the Baecke Physical Activity Questionnaire), depression, hamstring and hip flexor range of motion, low back extensor endurance, abdominal strength and endurance.ResultsA significant main effect of group was found for both pain (P=.019) and disability groups (P=.006). The min/no pain and pain groups differed in back endurance (114.2±38.8s vs 94.5±44.5s, respectively; P=.04). The no disability and disability groups differed in back endurance (116.3±35.9s vs 97.1±45.7s, respectively; P=.03) and the sports activity score of the Baecke Physical Activity Questionnaire (2.98±.95 vs 2.48±.85, respectively; P=.01). Subjects with hyperkyphotic postures compared with the normative thoracic group had higher depression scores (49 vs 38.5, respectively; P=.03) and less hamstring flexibility (30.5 vs 49.9, respectively; P<.001).ConclusionsBack extensor endurance was consistently different between both the pain and disability groups. Addressing limited low back extensor endurance and low levels of physical activity in young adults may have clinical relevance for the prevention and treatment of LBP and disability.     

Utilizing Hip Abduction Strength to Body-Weight Ratios in Return to Sport Decision-Making After ACL Reconstruction

BackgroundDespite the association between hip abduction weakness and non-contact anterior cruciate ligament (ACL) injury, hip abduction strength is rarely considered in return to sport decision-making following ACL reconstruction (ACLR).Hypothesis/PurposeThe purpose of this study was to compare self-reported function, objective functional test performance, and re-injury rates in patients with high (≥33%) versus low (<33% ) isometric hip abduction strength to body weight (BW) ratios when returning to activity following ACLR.Study DesignCohort studyMethodsData were gathered from a single-surgeon database and included baseline demographics. Clinical outcomes were assessed at the time of release to activity and included self-reported outcomes and a functional testing battery. Isometric hip abduction strength was obtained using a handheld dynamometer. Groups were dichotomized into those with low vs high strength to BW ratios. Two-year follow-up was performed using the single assessment numeric evaluation (SANE). Data were analyzed using univariate general linear models with an alpha level of .05.ResultsOf the 528 enrolled patients, 364 (68.9%) demonstrated a low strength to BW ratio. Baseline comparisons revealed more females and higher BMI (P <.05) in the <33% group. At release to activity, the <33% BW group demonstrated lower International Knee Documentation Committee survey scores (88.2 ± 13.6 vs 93.5 ± 10.3, P<.01), ACL-Return to Sport After Injury (76.2 ± 15.4 vs 88.5 ± 16.9, P<.01) scores, and isokinetic hamstring peak torque (P=.04). At 2-years, the <33% group reported lower SANE scores (83.3 ± 21.1 vs 92.83 ± 11.4, P=.05) with no significant differences in re-injuries.ConclusionPatients with low hip abduction strength to BW ratios demonstrated lower subjective function, psychological readiness, and isokinetic hamstring peak torque when completing functional testing following ACLR. Subjective deficits remained at 2-years.Level of EvidenceLevel 3Key TermsACL injury, hip abduction strength, return to sport, strength ratioClinical RelevanceAssessing isometric hip abduction strength to body weight ratio may be beneficial in determining readiness to return to sport following ACL reconstruction.What is Known About the SubjectThree prospective studies have provided conflicting evidence regarding the relationship between hip abduction strength and ACL injury. A clinical cut-point of hip abduction strength:BW ratio <35.4% has been suggested to identify athletes at risk of sustaining a non-contact ACL injury. To our knowledge no studies have examined isometric hip abduction strength:BW ratios in athletes attempting to return to sport following ACLR.What This Study Adds to Existing KnowledgeThis study examines the potential for hip abduction strength:BW ratio to be included as an additional metric in return to sport testing batteries.