Kinesiophobia and Its Association With Health-Related Quality of Life Across Injury Locations.

OBJECTIVE: To compare baseline kinesiophobia levels and their association with health-related quality of life across injury locations. DESIGN: Retrospective cross-sectional study. SETTING: Single, large outpatient physical therapy clinic within an academic medical center. PARTICIPANTS: Patients (N=1233) who underwent an initial evaluation for a diagnosis related to musculoskeletal pain and completed the 11-item version of the Tampa Scale for Kinesiophobia (TSK-11) and the Medical Outcomes Study 8-Item Short-Form Health Survey (SF-8) questionnaires within 7 days of their first visit were eligible for inclusion. Three hundred eighty patients were excluded because of missing data or because they were younger than 18 years. A total of 853 patients (mean age, 43.55y; range, 18-94y) were included. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Comparison of baseline kinesiophobia levels and their association with health-related quality of life across injury locations in an outpatient physical therapy setting. RESULTS: Separate analysis of variance models compared TSK-11 scores based on involved body region, and Pearson correlation coefficients were used to examine the association between TSK-11 scores and the SF-8 subscales at each body region. TSK-11 scores did not differ by body region (range, 23.9-26.1). Weak to moderate negative correlations existed between kinesiophobia and the SF-8 subscales. CONCLUSIONS: Kinesiophobia levels appear elevated and negatively associated with health-related quality of life at initial physical therapy evaluation regardless of injury location. These findings suggest that physical therapists in outpatient orthopedic settings should implement routine kinesiophobia assessment and provide stratified care based on kinesiophobia levels across musculoskeletal conditions.

Concussion May Increase the Risk of Subsequent Lower Extremity Musculoskeletal Injury in Collegiate Athletes.

BACKGROUND: Laboratory-based studies on neuromuscular control after concussion and epidemiological studies suggest that concussion may increase the risk of subsequent musculoskeletal injury. OBJECTIVE: The purpose of this study was to determine if athletes have an increased risk of lower extremity musculoskeletal injury after return to play from a concussion. METHODS: Injury data were collected from 2006 to 2013 for men's football and for women's basketball, soccer and lacrosse at a National Collegiate Athletic Association Division I university. Ninety cases of in-season concussion in 73 athletes (52 male, 21 female) with return to play at least 30 days prior to the end of the season were identified. A period of up to 90 days of in-season competition following return to play was reviewed for time-loss injury. The same period was studied in up to two control athletes who had no concussion within the prior year and were matched for sport, starting status and position. RESULTS: Lower extremity musculoskeletal injuries occurred at a higher rate in the concussed athletes (45/90 or 50 %) than in the non-concussed athletes (30/148 or 20 %; P < 0.01). The odds of sustaining a musculoskeletal injury were 3.39 times higher in the concussed athletes (95 % confidence interval 1.90-6.05; P < 0.01). Overall, the number of days lost because of injury was similar between concussed and non-concussed athletes (median 9 versus 15; P = 0.41). CONCLUSIONS: The results of this study demonstrate a relationship between concussion and an increased risk of lower extremity musculoskeletal injury after return to play, and may have implications for current medical practice standards regarding evaluation and management of concussion injuries.

Lower Extremity Stiffness Changes after Concussion in Collegiate Football Players.

PURPOSE: Recent research indicates that a concussion increases the risk of musculoskeletal injury. Neuromuscular changes after concussion might contribute to the increased risk of injury. Many studies have examined gait postconcussion, but few studies have examined more demanding tasks. This study compared changes in stiffness across the lower extremity, a measure of neuromuscular function, during a jump-landing task in athletes with a concussion (CONC) to uninjured athletes (UNINJ). METHODS: Division I football players (13 CONC and 26 UNINJ) were tested pre- and postseason. A motion capture system recorded subjects jumping on one limb from a 25.4-cm step onto a force plate. Hip, knee, and ankle joint stiffness were calculated from initial contact to peak joint flexion using the regression line slopes of the joint moment versus the joint angle plots. Leg stiffness was (peak vertical ground reaction force [PVGRF]/lower extremity vertical displacement) from initial contact to peak vertical ground reaction force. All stiffness values were normalized to body weight. Values from both limbs were averaged. General linear models compared group (CONC, UNINJ) differences in the changes of pre- and postseason stiffness values. RESULTS: Average time from concussion to postseason testing was 49.9 d. The CONC group showed an increase in hip stiffness (P = 0.03), a decrease in knee (P = 0.03) and leg stiffness (P = 0.03), but no change in ankle stiffness (P = 0.65) from pre- to postseason. CONCLUSION: Lower extremity stiffness is altered after concussion, which could contribute to an increased risk of lower extremity injury. These data provide further evidence of altered neuromuscular function after concussion.

Low- Versus High-Intensity Plyometric Exercise During Rehabilitation After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Plyometric exercise is used during rehabilitation after anterior cruciate ligament (ACL) reconstruction to facilitate the return to sports participation. However, clinical outcomes have not been examined, and high loads on the lower extremity could be detrimental to knee articular cartilage. PURPOSE: To compare the immediate effect of low- and high-intensity plyometric exercise during rehabilitation after ACL reconstruction on knee function, articular cartilage metabolism, and other clinically relevant measures. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: Twenty-four patients who underwent unilateral ACL reconstruction (mean, 14.3 weeks after surgery; range, 12.1-17.7 weeks) were assigned to 8 weeks (16 visits) of low- or high-intensity plyometric exercise consisting of running, jumping, and agility activities. Groups were distinguished by the expected magnitude of vertical ground-reaction forces. Testing was conducted before and after the intervention. Primary outcomes were self-reported knee function (International Knee Documentation Committee [IKDC] subjective knee form) and a biomarker of articular cartilage degradation (urine concentrations of crosslinked C-telopeptide fragments of type II collagen [uCTX-II]). Secondary outcomes included additional biomarkers of articular cartilage metabolism (urinary concentrations of the neoepitope of type II collagen cleavage at the C-terminal three-quarter-length fragment [uC2C], serum concentrations of the C-terminal propeptide of newly formed type II collagen [sCPII]) and inflammation (tumor necrosis factor-α), functional performance (maximal vertical jump and single-legged hop), knee impairments (anterior knee laxity, average knee pain intensity, normalized quadriceps strength, quadriceps symmetry index), and psychosocial status (kinesiophobia, knee activity self-efficacy, pain catastrophizing). The change in each measure was compared between groups. Values before and after the intervention were compared with the groups combined. RESULTS: The groups did not significantly differ in the change of any primary or secondary outcome measure. Of interest, sCPII concentrations tended to change in opposite directions (mean ± SD: low-intensity group, 28.7 ± 185.5 ng/mL; high-intensity group, -200.6 ± 255.0 ng/mL; P = .097; Cohen d = 1.03). Across groups, significant changes after the intervention were increased the IKDC score, vertical jump height, normalized quadriceps strength, quadriceps symmetry index, and knee activity self-efficacy and decreased average knee pain intensity. CONCLUSION: No significant differences were detected between the low- and high-intensity plyometric exercise groups. Across both groups, plyometric exercise induced positive changes in knee function, knee impairments, and psychosocial status that would support the return to sports participation after ACL reconstruction. The effect of plyometric exercise intensity on articular cartilage requires further evaluation. REGISTRATION NUMBER: Clinicaltrials.gov NCT01851655.

Comparison of physical impairment, functional, and psychosocial measures based on fear of reinjury/lack of confidence and return-to-sport status after ACL reconstruction.

BACKGROUND: Fear of reinjury and lack of confidence influence return-to-sport outcomes after anterior cruciate ligament (ACL) reconstruction. The physical, psychosocial, and functional recovery of patients reporting fear of reinjury or lack of confidence as their primary barrier to resuming sports participation is unknown. PURPOSE: To compare physical impairment, functional, and psychosocial measures between subgroups based on return-to-sport status and fear of reinjury/lack of confidence in the return-to-sport stage and to determine the association of physical impairment and psychosocial measures with function for each subgroup at 6 months and 1 year after surgery. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Physical impairment (quadriceps index [QI], quadriceps strength/body weight [QSBW], hamstring:quadriceps strength ratio [HQ ratio], pain intensity), self-report of function (International Knee Documentation Committee [IKDC]), and psychosocial (Tampa Scale for Kinesiophobia-shortened form [TSK-11]) measures were collected at 6 months and 1 year after surgery in 73 patients with ACL reconstruction. At 1 year, subjects were divided into "return-to-sport" (YRTS) or "not return-to-sport" (NRTS) subgroups based on their self-reported return to preinjury sport status. Patients in the NRTS subgroup were subcategorized as NRTS-Fear/Confidence if fear of reinjury/lack of confidence was the primary reason for not returning to sports, and all others were categorized as NRTS-Other. RESULTS: A total of 46 subjects were assigned to YRTS, 13 to NRTS-Other, and 14 to NRTS-Fear/Confidence. Compared with the YRTS subgroup, the NRTS-Fear/Confidence subgroup was older and had lower QSBW, lower IKDC score, and higher TSK-11 score at 6 months and 1 year; however, they had similar pain levels. In the NRTS-Fear/Confidence subgroup, the IKDC score was associated with QSBW and pain at 6 months and QSBW, QI, pain, and TSK-11 scores at 1 year. CONCLUSION: Elevated pain-related fear of movement/reinjury, quadriceps weakness, and reduced IKDC score distinguish patients who are unable to return to preinjury sports participation because of fear of reinjury/lack of confidence. Despite low average pain ratings, fear of pain may influence function in this subgroup. Assessment of fear of reinjury, quadriceps strength, and self-reported function at 6 months may help identify patients at risk for not returning to sports at 1 year and should be considered for inclusion in return-to-sport guidelines.

Observational ratings of frontal plane knee position are related to the frontal plane projection angle but not the knee abduction angle during a step-down task.

STUDY DESIGN: Laboratory study, cross-sectional. OBJECTIVES: To determine if the magnitude of frontal plane knee angle, as determined with a 3-D motion-capture system (knee abduction angle [KAA]) or digital video (frontal plane projection angle [FPPA]), varies among groups of individuals with different frontal plane knee position, as determined by observational ratings. BACKGROUND: Performing functional tasks with the knee positioned medial to the foot may increase the risk for knee injury. The KAA and FPPA are commonly used in research settings to determine injury risk. However, observational ratings of frontal plane knee position are easier to perform in the clinical setting. It is not clear whether observational ratings of knee position can be used as a surrogate for the KAA or FPPA. METHODS: Eighty-one female collegiate athletes performed a lateral step-down task. Participants were rated as good, fair, or poor based on observation of their knee position relative to the foot in the frontal plane and assigned to observational rating groups. Movement was concurrently recorded with a 3-D motion-capture system and a digital video camera to calculate KAA and FPPA, respectively. RESULTS: Knee abduction angle did not differ among participants assigned to the different observational rating groups (P = .265). In contrast, FPPA values differed between groups (P<.001), with the highest values in the poor group and the lowest values in the good group. CONCLUSION: Observational ratings of frontal plane knee position relative to the foot are an appropriate clinical substitute for FPPA but not KAA. Therefore, observational ratings of medial knee position may be more suitable as a clinical screening tool when FPPA is the measure of interest.

Normalization considerations for using the unilateral seated shot put test in rehabilitation.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To examine the effect of different normalization methods on unilateral seated shot put test results. BACKGROUND: The unilateral seated shot put test could assist clinical decision making in upper extremity rehabilitation, but test results must be normalized to compare across patients. The effect of normalization methods based on body size and upper-limb dominance is unknown. METHODS: One hundred twenty-five collegiate athletes (63 males) performed the unilateral seated shot put test with each upper extremity. Anthropometric measures (height, body mass, arm length) and distance thrown were recorded. Normalization based on body size included ratio scaling and allometric scaling. Ratio scaling was performed with the anthropometric measure having the highest correlation to distance thrown (distance/anthropometric measure). Allometric scaling was performed with body mass raised to the theoretical exponent 0.67 (distance/body mass(0.67)) and a derived exponent. Correlations of nonnormalized and normalized values with body mass were then determined. The limb symmetry index [(dominant-side distance/nondominantside distance) × 100] was used for normalization based on limb dominance. Sex differences were examined. RESULTS: Body mass was selected for ratio scaling, and 0.35 was the derived allometric-scaling exponent. Across sexes, only allometric scaling with the exponent 0.35 removed the correlation with body mass. The mean limb symmetry index exceeded 100% in males (108.7%) and females (104.4%). All normalized test results were higher in males. CONCLUSION: When using the unilateral seated shot put test in rehabilitation, allometric scaling with the exponent 0.35 is preferable, limb comparisons should account for 5% to 10% better performance on the dominant side, and performance benchmarks should be set within sex. J Orthop Sports Phys Ther 2014;44(7):518-524. Epub 10 May 2014. doi:10.2519/jospt.2014.5004.

Return to preinjury sports participation following anterior cruciate ligament reconstruction: contributions of demographic, knee impairment, and self-report measures.

STUDY DESIGN: Cross-sectional cohort. OBJECTIVES: (1) To examine differences in clinical variables (demographics, knee impairments, and self-report measures) between those who return to preinjury level of sports participation and those who do not at 1 year following anterior cruciate ligament reconstruction, (2) to determine the factors most strongly associated with return-to-sport status in a multivariate model, and (3) to explore the discriminatory value of clinical variables associated with return to sport at 1 year postsurgery. BACKGROUND: Demographic, physical impairment, and psychosocial factors individually prohibit return to preinjury levels of sports participation. However, it is unknown which combination of factors contributes to sports participation status. METHODS: Ninety-four patients (60 men; mean age, 22.4 years) 1 year post-anterior cruciate ligament reconstruction were included. Clinical variables were collected and included demographics, knee impairment measures, and self-report questionnaire responses. Patients were divided into "yes return to sports" or "no return to sports" groups based on their answer to the question, "Have you returned to the same level of sports as before your injury?" Group differences in demographics, knee impairments, and self-report questionnaire responses were analyzed. Discriminant function analysis determined the strongest predictors of group classification. Receiver-operating-characteristic curves determined the discriminatory accuracy of the identified clinical variables. RESULTS: Fifty-two of 94 patients (55%) reported yes return to sports. Patients reporting return to preinjury levels of sports participation were more likely to have had less knee joint effusion, fewer episodes of knee instability, lower knee pain intensity, higher quadriceps peak torque-body weight ratio, higher score on the International Knee Documentation Committee Subjective Knee Evaluation Form, and lower levels of kinesiophobia. Knee joint effusion, episodes of knee instability, and score on the International Knee Documentation Committee Subjective Knee Evaluation Form were identified as the factors most strongly associated with self-reported return-to-sport status. The highest positive likelihood ratio for the yes-return-to-sports group classification (14.54) was achieved when patients met all of the following criteria: no knee effusion, no episodes of instability, and International Knee Documentation Committee Subjective Knee Evaluation Form score greater than 93. CONCLUSION: In multivariate analysis, the factors most strongly associated with return-to-sport status included only self-reported knee function, episodes of knee instability, and knee joint effusion.

Longitudinal changes in psychosocial factors and their association with knee pain and function after anterior cruciate ligament reconstruction.

BACKGROUND: Evidence in the musculoskeletal rehabilitation literature suggests that psychosocial factors can influence pain levels and functional outcome. OBJECTIVE: The purpose of this study was to examine changes in select psychosocial factors and their association with knee pain and function over 12 weeks after anterior cruciate ligament (ACL) reconstruction. DESIGN: This was a prospective, longitudinal, observational study. METHODS: Patients with ACL reconstruction completed self-report questionnaires for average knee pain intensity (numeric rating scale [NRS]), knee function (International Knee Documentation Committee Subjective Knee Form [IKDC-SKF]), and psychosocial factors (pain catastrophizing [Pain Catastrophizing Scale], fear of movement or reinjury [shortened version of the Tampa Scale for Kinesiophobia (TSK-11)], and self-efficacy for rehabilitation tasks [modified Self-Efficacy for Rehabilitation Outcome Scale (SER)]). Data were collected at 4 time points after surgery (baseline and 4, 8, and 12 weeks). Repeated-measures analyses of variance determined changes in questionnaire scores across time. Hierarchical linear regression models were used to examine the association of psychosocial factors with knee pain and function. RESULTS: Seventy-seven participants completed the study. All questionnaire scores changed across 12 weeks. Baseline psychosocial factors did not predict the 12-week NRS or IKDC-SKF score. The 12-week change in modified SER score predicted the 12-week change in NRS score (r(2)=.061), and the 12-week change in modified SER and TSK-11 scores predicted the 12-week change in IKDC-SKF score (r(2)=.120). LIMITATIONS: The psychometric properties of the psychosocial factor questionnaires are unknown in people with ACL reconstruction. The study focused on short-term outcomes using only self-report measures. CONCLUSIONS: Psychosocial factors are potentially modifiable early after ACL reconstruction. Baseline psychosocial factor levels did not predict knee pain or function 12 weeks postoperatively. Interventions that increase self-efficacy for rehabilitation tasks or decrease fear of movement or reinjury may have potential to improve short-term outcomes for knee pain and function.

Morbid obesity is associated with fear of movement and lower quality of life in patients with knee pain-related diagnoses.

OBJECTIVE: To compare fear of movement in patients with different body mass index (BMI) values referred for rehabilitative care of the knee and to examine whether this fear contributed to self-reported knee-related function. We hypothesized that fear of movement would be elevated with increasing BMI and that fear would correspond with lower self-report knee-related function and lower quality of life (QOL). DESIGN: Retrospective cross-sectional study. SETTING: Outpatient therapy clinic affiliated with a tertiary care hospital. PATIENTS: Patients with knee pain diagnoses (n = 278) were stratified into 4 BMI groups (in < or =25 kg/m(2) nonobese; 25-29.9 kg/m(2) overweight; 30-39.9 kg/m(2) obese; > or =40 kg/m(2) morbidly obese). MAIN OUTCOME MEASUREMENTS: The Tampa Scale of Kinesiophobia (TSK; fear of movement), International Knee Documentation (IKDC; knee function), and Short-Form 8 (SF-8; QOL) scores were main outcomes. Pain and straight leg raise test scores also were collected. METHODS: After review of the medical records, descriptive statistics and nonparametric tests were performed, and TSK, QOL, and SF-8 scores were compared. Hierarchical regression modeling determined the contribution of TSK scores to the variance of IKDC scores. RESULTS: Pain scores were greatest in the nonobese group and lowest in the morbidly obese group (7.5 +/- 2.6 points vs 4.8 +/- 3.1 points; P < .05). TSK scores in morbidly obese patients were greater than in nonobese patients (27.1 +/- 7.7 points vs 22.0 +/- 6.6 points; P = .002). The SF-8 mental-physical subscores were 27% to 32% lower in the morbidly obese than nonobese patients (both P < .0001). IKDC scores were lower in the morbidly obese than nonobese patients (32.1 +/- 19.2 points vs 50.9 +/- 23.8 points; P = .0001). Pain severity and TSK scores contributed 28.6% and 7.1% to the variance of the IKDC scores (overall R(2) = 68.6). CONCLUSIONS: Morbid obesity is associated with elevated fear of movement. Pain was the strongest predictor of IKDC scores, and fear of movement enhanced this predictive value of the regression model. Despite lower absolute pain severity in the morbidly obese group, this fear may influence IKDC scores in this population. Morbidly obese patients might benefit from rehabilitation activities that reduce fear of movement to optimize participation in rehabilitation activity.

Factors associated with function after anterior cruciate ligament reconstruction.

BACKGROUND: Many individuals do not resume unrestricted, preinjury sports participation after anterior cruciate ligament reconstruction, thus a better understanding of factors associated with function is needed. The purpose of this study was to investigate the association of knee impairment and psychological variables with function in subjects with anterior cruciate ligament reconstruction. HYPOTHESIS: After controlling for demographic variables, knee impairment and psychological variables contribute to function in subjects with anterior cruciate ligament reconstruction. STUDY DESIGN: Cross-sectional study; Level of evidence, 4a. METHODS: Fifty-eight subjects with a unilateral anterior cruciate ligament reconstruction completed a standardized testing battery for knee impairments (range of motion, effusion, quadriceps strength, anterior knee joint laxity, and pain intensity), kinesiophobia (shortened Tampa Scale for Kinesiophobia), and function (International Knee Documentation Committee subjective form and single-legged hop test). Separate 2-step regression analyses were conducted with International Knee Documentation Committee subjective form score and single-legged hop index as dependent variables. Demographic variables were entered into the model first, followed by knee impairment measures and Tampa Scale for Kinesiophobia score. RESULTS: A combination of pain intensity, quadriceps index, Tampa Scale for Kinesiophobia score, and flexion motion deficit contributed to the International Knee Documentation Committee subjective form score (adjusted r(2) = 0.67; P < .001). Only effusion contributed to the single-legged hop index (adjusted r(2) = 0.346; P = .002). CONCLUSION: Knee impairment and psychological variables in this study were associated with self-report of function, not a performance test. CLINICAL RELEVANCE: The results support focusing anterior cruciate ligament reconstruction rehabilitation on pain, knee motion deficits, and quadriceps strength, as well as indicate that kinesiophobia should be addressed. Further research is needed to reveal which clinical tests are associated with performance testing.

The association of pain and fear of movement/reinjury with function during anterior cruciate ligament reconstruction rehabilitation.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To measure fear of movement/reinjury levels and determine the association with function at different timeframes during anterior cruciate ligament (ACL) reconstruction rehabilitation. We hypothesized that fear of movement/reinjury would decrease during rehabilitation and be inversely related with function. BACKGROUND: Fear of movement/reinjury can prevent return to sports after ACL reconstruction, but it has not been studied during rehabilitation. METHODS AND MEASURES: Demographic data and responses on the shortened version of Tampa Scale for Kinesiophobia (TSK-11), 8-Item Short-Form Health Survey (SF-8), and International Knee Documentation Committee (IKDC) subjective form were extracted from a clinical database for 97 patients in the first year after ACL reconstruction. Three groups were formed: group 1, less than or equal to 90 days; group 2, 91 to 180 days; group 3: 181 to 372 days post-ACL reconstruction. Group differences in TSK-11 score, SF-8 bodily pain rating, and IKDC scores were determined. Hierarchical linear regression models were created for each group, with IKDC score as the dependent variable and demographic factors, SF-8 bodily pain rating, and TSK-11 score as independent variables. RESULTS: TSK-11 score was higher in group 1 than in group 3 (P < .05). Across the groups, SF-8 bodily pain rating decreased (P < .001) and IKDC score increased (P < .001). SF-8 bodily pain rating was a significant factor in the regression model for all groups, whereas TSK-11 score only contributed to the regression model in group 3 (partial correlation, -0.529). CONCLUSIONS: Pain was consistently associated with function across the timeframes studied. Fear of movement/reinjury levels appear to decrease during ACL reconstruction rehabilitation and are associated with function in the timeframe when patients return to sports. LEVEL OF EVIDENCE: Prognosis, level 4.

Investigation of clinician agreement in evaluating movement quality during unilateral lower extremity functional tasks: a comparison of 2 rating methods.

STUDY DESIGN: Nonexperimental. OBJECTIVES: To determine interrater and intrarater agreement for 2 methods of evaluating movement quality during 2 lower extremity functional tasks, and to descriptively compare levels of agreement between the 2 methods. BACKGROUND: Clinicians typically use observational analysis to evaluate movement quality during functional tasks, but the extent of agreement is unknown. METHODS AND MEASURES: Twenty-five uninjured subjects performed 3 trials of unilateral squat and lateral step-down tasks. Three clinicians evaluated the trunk, pelvis, and hips for coronal plane and transverse plane movement deviations. Two rating methods were used: assessment of the entire movement ("overall method") and rating each segment individually ("specific method"). Movement deviation severity was rated using basic clinical guidelines and ratings were repeated from videotape. Percent agreement and weighted kappa coefficients were calculated between rater pairs and rating sessions. Generalized kappa coefficients were calculated across raters. RESULTS: Interrater and intrarater percent agreement were higher using the overall method. Interrater weighted kappa coefficients were similar between rating methods (overall method, 0-0.55; specific method, 0.23-0.53). Intrarater weighted kappa coefficients were higher for the specific method (0.38-0.68) compared to the overall method (0.13-0.50). Generalized kappa coefficients were also higher for specific method compared to the overall method (unilateral squat, 0.19 and 0.01, respectively; lateral step-down, 0.22 and 0.18, respectively) and 95% confidence intervals remained above zero. CONCLUSIONS: Rating movement at body segments appears to result in agreement among raters that is better than chance. Neither rating method produced high agreement, indicating a need to develop more explicit criteria for rating movement deviation severity.

Deficit in human muscle strength with cast immobilization: contribution of inorganic phosphate.

Metabolic factors have been proposed to explain strength deficits observed in skeletal muscle with immobilization that are not completely accounted for by changes in muscle cross-sectional area (CSA) and neural adaptations. The aim of this study was to quantify changes in the resting inorganic phosphate (Pi) concentration from the medial gastrocnemius muscle during immobilization, reloading and rehabilitation. Additionally, we assessed the contributions of CSA, muscle activation and Pi concentration to plantar flexor torque during rehabilitation following immobilization. Eight persons with a surgically stabilized ankle fracture participated. Subjects were immobilized for 6-8 weeks and subsequently participated in 10 weeks of rehabilitation. Localized (31)P-Magnetic resonance spectroscopy, magnetic resonance imaging, isometric torque and activation testing were performed on the immobilized and uninvolved limbs. At 6 weeks of immobilization, significant differences were noted between the immobilized and uninvolved limbs for the Pi concentration and the Pi/PCr ratio (P < 0.05). From 6 weeks of immobilization to 3-5 days of reloading, the increase in Pi concentration (15%, P = 0.26) and Pi/PCr (20%, P = 0.29) was not significant. During rehabilitation, the relative contributions of CSA, muscle activation and Pi concentration to plantarflexor torque were 32, 44 and 40%, respectively. Together, CSA, muscle activation and Pi concentration accounted for 76% of the variance in torque (P < 0.01). In summary, our findings suggest that immobilization, independent of reloading, leads to a significant increase in the resting Pi concentration of human skeletal muscle. Additionally, alterations in resting Pi concentration may contribute to strength deficits with immobilization not accounted for by changes in muscle CSA or neural adaptations.

Relative contributions of muscle activation and muscle size to plantarflexor torque during rehabilitation after immobilization.

Muscle atrophy is clearly related to a loss of muscle torque, but the reduction in muscle size cannot entirely account for the decrease in muscle torque. Reduced neural input to muscle has been proposed to account for much of the remaining torque deficits after disuse or immobilization. The purpose of this investigation was to assess the relative contributions of voluntary muscle activation failure and muscle atrophy to loss of plantarflexor muscle torque after immobilization. Nine subjects (ages 19-23) years with unilateral ankle malleolar fractures were treated by open reduction-internal fixation and 7 weeks of cast immobilization. Subjects participated in 10 weeks of rehabilitation that focused on both strength and endurance of the plantarflexors. Magnetic resonance imaging, isometric plantarflexor muscle torque and activation (interpolated twitch technique) measurements were performed at 0, 5, and 10 weeks of rehabilitation. Following immobilization, voluntary muscle activation (56.8 +/- 16.3%), maximal cross-sectional area (CSA) (35.3 +/- 7.6 cm(2)), and peak torque (26.2 +/- 12.7 N-m) were all significantly decreased ( p < 0.0056) compared to the uninvolved limb (98.0 +/- 2.3%, 48.0 +/- 6.8 cm(2), and 105.2 +/- 27.0 N-m, respectively). During 10 weeks of rehabilitation, muscle activation alone accounted for 56.1% of the variance in torque ( p < 0.01) and muscle CSA alone accounted for 35.5% of the variance in torque ( p < 0.01). Together, CSA and muscle activation accounted for 61.5% of the variance in torque ( p < 0.01). The greatest gains in muscle activation were made during the first 5 weeks of rehabilitation. Both increases in voluntary muscle activation and muscle hypertrophy contributed to the recovery in muscle strength following immobilization, with large gains in activation during the first 5 weeks of rehabilitation. In contrast, muscle CSA showed fairly comparable gains throughout both the early and later phase of rehabilitation.

Plyometric exercise in the rehabilitation of athletes: physiological responses and clinical application.

Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.

Rotational motion changes in the glenohumeral joint of the adolescent/Little League baseball player.

BACKGROUND: Differences in range of motion and rotational motion between the dominant and nondominant shoulders in throwing athletes are well documented, although the age at which these changes begin to occur is not known. HYPOTHESIS: Changes in glenohumeral rotational motion in the shoulder of the Little League/adolescent baseball player occur during the most formative years of physical development. STUDY DESIGN: Cross-sectional study. METHODS: Elevation, internal rotation at 90 degrees of abduction, and external rotation at 90 degrees of abduction were measured in the dominant and nondominant shoulders of 294 baseball players, aged 8 to 16 years. RESULTS: Analysis of variance revealed 2-way interactions between arm dominance by age for elevation (P = .005) and internal rotation (P = .001). Significant differences were noted between dominant and nondominant arms for internal rotation at 90 degrees (P = .001) and external rotation at 90 degrees (P = .001). Elevation, internal rotation at 90 degrees , external rotation at 90 degrees , and total range of motion varied significantly (P = .001) among age groups. Elevation in the dominant arms of 16-year-olds was on average 5.3 degrees less than in 8-year-olds (179.6 degrees vs 174.3 degrees ). In the nondominant arms, mean elevation for 16-year-olds was 5.6 degrees less than in 8-year-olds (179.7 degrees vs 174.1 degrees ). Internal rotation at 90 degrees for the dominant arms averaged 39.0 degrees at age 8 and only 21.3 degrees at age 16. In the non-dominant arms, internal rotation for 8-year-olds averaged 42.2 degrees and only 33.1 degrees for 16-year-olds. CONCLUSIONS: Elevation and total range of motion decreased as age increased. These changes may be consequences of both bone and soft tissue adaptation. The most dramatic decline in total range of motion was seen between the 13-year-olds and 14-year-olds, in the year before peak incidence of Little Leaguer's shoulder. This decrease in rotational motion may cause increased stress at the physis during throwing.

Muscle adaptations with immobilization and rehabilitation after ankle fracture.

UNLABELLED: INTRODUCTION/ PURPOSE: The widespread occurrence of muscular atrophy during immobilization and its reversal presents an important challenge to rehabilitation medicine. We used 3D-magnetic resonance imaging (MRI) in patients with surgically-stabilized ankle mortise fractures to quantify changes in plantarflexor and dorsiflexor muscle size during immobilization and rehabilitation, as well as to evaluate changes in force generating capacity (specific torque). METHODS: Twenty-individuals participated in a 10 wk rehabilitation program after 7 wk of immobilization. MRIs were acquired at baseline, 2, and 7 wk of immobilization, and at 5 and 10 wk of rehabilitation. Isometric plantarflexor muscle strength testing was performed at 0, 5, and 10 wk of rehabilitation. RESULTS: Dorsiflexors and plantarflexors atrophied 18.9% and 24.4% respectively, the majority of which occurred during the first 2 wk of immobilization (dorsiflexors: 9.6%; plantarflexors: 14.1%). Likewise, more than 50% of hypertrophy during rehabilitation occurred within the first 5 wk of rehabilitation for both the dorsiflexors (12.9%) and plantarflexors (13.2%), when compared to the total amount of hypertrophy over 10 wk of rehabilitation (dorsiflexors: 17.6%, plantarflexors: 22.5%). There were no significant differences in hypertrophy or atrophy of the dorsiflexor or plantarflexor muscles, despite a rehabilitation emphasis on the plantarflexors. Patients had significantly lower plantarflexor specific torque (torque/CSA) than healthy, control subjects immediately after cast immobilization, which did not return to normal after 10 wk of rehabilitation (P < 0.05). CONCLUSION: Our investigation of the consequences of limb immobilization on rehabilitation outcomes in patients can be applied directly to optimizing rehabilitation programs. Although muscle hypertrophy occurred early during rehabilitation, plantarflexor muscle function (specific torque) should remain the focus of rehabilitation programs because although CSA recovered quickly, specific torque still lagged behind that of control subjects.