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Background: Given the relatively high risk of contralateral anterior cruciate ligament (ACL) injury in patients with ACL reconstruction (ACLR), there is a need to understand intrinsic risk factors that may contribute to contralateral injury. Hypothesis: The ACLR group would have smaller ACL volume and a narrower femoral notch width than healthy individuals after accounting for relevant anthropometrics. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: Magnetic resonance imaging data of the left knee were obtained from uninjured (N = 11) and unilateral ACL-reconstructed (N = 10) active, female, collegiate-level recreational athletes. ACL volume was obtained from T2-weighted images. Femoral notch width and notch width index were measured from T1-weighted images. Independent-samples t tests examined differences in all measures between healthy and ACLR participants. Results: The ACLR group had a smaller notch width index (0.22 ± 0.02 vs 0.25 ± 0.01; P = 0.004; effect size, 1.41) and ACL volume (25.6 ± 4.0 vs 32.6 ± 8.2 mm3/(kg·m)−1; P = 0.025; effect size, 1.08) after normalizing by body size. Conclusion: Only after normalizing for relevant anthropometrics, the contralateral ACLR limb had smaller ACL size and narrower relative femoral notch size than healthy individuals. These findings suggest that risk factor studies of ACL size and femoral notch size should account for relevant body size when determining their association with contralateral ACL injury. Clinical Relevance: The present study shows that the method of the identified intrinsic risk factors for contralateral ACL injury could be used in future clinical screening settings.

Context Females have consistently higher anterior cruciate ligament (ACL) injury rates than males. The reasons for this disparity are not fully understood. Whereas ACL morphometric characteristics are associated with injury risk and females have a smaller absolute ACL size, comprehensive sex comparisons that adequately account for sex differences in body mass index (BMI) have been limited. Objective To investigate sex differences among in vivo ACL morphometric measures before and after controlling for femoral notch width and BMI. Design Cross-sectional study. Setting Laboratory. Patients or Other Participants Twenty recreationally active men (age = 23.2 ± 2.9 years, height = 180.4 ± 6.7 cm, mass = 84.0 ± 10.9 kg) and 20 recreationally active women (age = 21.3 ± 2.3 years, height = 166.9 ± 7.7 cm, mass = 61.9 ± 7.2 kg) participated. Main Outcome Measure(s) Structural magnetic resonance imaging sequences were performed on the left knee. Anterior cruciate ligament volume, width, and cross-sectional area measures were obtained from T2-weighted images and normalized to femoral notch width and BMI. Femoral notch width was measured from T1-weighted images. We used independent-samples t tests to examine sex differences in absolute and normalized measures. Results Men had greater absolute ACL volume (1712.2 ± 356.3 versus 1200.1 ± 337.8 mm3; t38 = −4.67, P < .001) and ACL width (8.5 ± 2.3 versus 7.0 ± 1.2 mm; t38 = −2.53, P = .02) than women. The ACL volume remained greater in men than in women after controlling for femoral notch width (89.31 ± 15.63 versus 72.42 ± 16.82 mm3/mm; t38 = −3.29, P = .002) and BMI (67.13 ± 15.40 versus 54.69 ± 16.39 mm3/kg/m2; t38 = −2.47, P = .02). Conclusions Whereas men had greater ACL volume and width than women, only ACL volume remained different when we accounted for femoral notch width and BMI. This suggests that ACL volume may be an appropriate measure of ACL anatomy in investigations of ACL morphometry and ACL injury risk that include sex comparisons.

Background: High anterior knee laxity (AKL) has been prospectively identified as a risk factor for anterior cruciate ligament (ACL) injuries. Given that ACL morphometry and structural composition have the potential to influence ligamentous strength, understanding how these factors are associated with greater AKL is warranted. Hypothesis: Smaller ACL volumes combined with longer T2* relaxation times would collectively predict greater AKL. Study Design: Cross-sectional study; Level of evidence, 3. Methods: College-aged active male (n = 20) and female (n = 30) participants underwent magnetic resonance imaging (MRI) and AKL testing. T2-weighted MRI scans were used to assess ACL volumes, and T2* relaxation times were used to assess ACL structural composition. AKL was measured via a commercial knee arthrometer. Forward stepwise linear regression with sex and weight (first step; suppressor variables) as well as ACL volume and T2* relaxation time (second step; independent variables) was used to predict AKL (dependent variable). Results: After initially adjusting for sex and weight ( R 2 = 0.19; P = .006), smaller ACL volumes combined with longer T2* relaxation times collectively predicted greater AKL ( R 2 = 0.52; P < .001; R 2 Δ = 0.32; P Δ < .001). A smaller ACL volume was the primary predictor of greater AKL ( R 2 Δ = 0.28; P < .001), with a longer T2* relaxation time trending toward a significant contribution to greater AKL ( R 2 Δ = 0.04; P = .062). After adjusting for ACL volume and T2* relaxation time, sex (partial r = 0.05; P = .735) and weight (partial r = 0.05; P = .725) were no longer significant predictors. Conclusion: AKL was largely predicted by ACL volume and to a lesser extent by T2* relaxation time (and not a person’s sex and weight). These findings enhance our understanding of how AKL may be associated with a structurally weaker ACL. The current study presents initial evidence that AKL is a cost-effective and clinically accessible measure that shows us something about the structural composition of the ACL. As AKL has been consistently shown to be a risk factor for ACL injuries, work should be done to continue to investigate what AKL may tell a clinician about the structure and composition of the ACL.

Drop landings and drop jumps are common training exercises and injury research model tasks. Drop landings have a single landing, whereas drop jumps include a subsequent jump after initial landing. With the expected ground impact, instant and landing surface suggested to modulate landing neuromechanics, muscle activity, and kinetics should be the same in both tasks when landing from the same height onto the same surface. Although previous researchers have noted some differences between these tasks across separate studies, little research has compared these tasks in the same study. Thus, we examined whether a subsequent movement after initial landing alters muscle activity and kinetics between drop landings and jumps. Fifteen women performed 10 drop landings and drop jumps each from 45 cm. Muscle onsets and integrated muscle activation amplitudes 150 milliseconds before (preactivity) and after landing (postactivity) in the medial and lateral quadriceps, hamstrings, and lateral gastrocnemius and peak and time-to-peak vertical ground reaction forces were examined across tasks (p

Context: Multiple factors have been suggested to increase the risk of faulty dynamic alignments that predict noncontact anterior cruciate ligament injury. Few researchers have examined this relationship using an integrated, multifactorial approach.Objective: To describe the relationship among static lower extremity alignment (LEA), hip muscle activation, and hip and knee motion during a single-leg squat.Design: Descriptive laboratory study.Setting: Research laboratory.Patients or Other Participants: Thirty men (age = 23.9 ± 3.6 years, height = 178.5 ± 9.9 cm, mass = 82.0 ± 14.1 kg) and 30 women (age = 22.2 ± 2.6 years, height = 162.4 ± 6.3 cm, mass = 60.3 ± 8.1 kg).Main Outcome Measure(s): Pelvic angle, femoral anteversion, quadriceps angle, tibiofemoral angle, and genu recurvatum were measured to the nearest degree; navicular drop was measured to the nearest millimeter. The average root mean square amplitude of the gluteus medius and maximus muscles was assessed during the single-leg squat and normalized to the peak root mean square value during maximal contractions for each muscle. Kinematic data of hip and knee were also assessed during the single-leg squat. Structural equation modeling was used to describe the relationships among static LEA, hip muscle activation, and joint kinematics, while also accounting for an individual's sex and hip strength.Results: Smaller pelvic angle and greater femoral anteversion, tibiofemoral angle, and navicular drop predicted greater hip internal-rotation excursion and knee external-rotation excursion. Decreased gluteus maximus activation predicted greater hip internal-rotation excursion but decreased knee valgus excursion. No LEA characteristic predicted gluteus medius or gluteus maximus muscle activation during the single-leg squat.Conclusions: Static LEA, characterized by a more internally rotated hip and valgus knee alignment and less gluteus maximus activation, was related to commonly observed components of functional valgus collapse during the single-leg squat. This exploratory analysis suggests that LEA does not influence hip muscle activation in controlling joint motion during a single-leg squat.

Changes in anterior knee laxity (AKL), genu recurvatum (GR) and general joint laxity (GJL) were quantified across days of the early follicular and early luteal phases of the menstrual cycle in 66 females, and the similarity in their pattern of cyclic variations examined. Laxity was measured on each of the first 6 days of menses (M1–M6) and the first 8 days following ovulation (L1–L8) over two cycles. The largest mean differences were observed between L5 and L8 for AKL (0.32mm), and between L5 and M1 for GR (0.56°) and GJL (0.26)(P

ABOUT 80,000 to 250,000 anterior cruciate ligament (ACL) injuries of the knee occur annually, with many of these injuries affecting individuals between the ages of 15-25 years. 1 The majority of ACL injuries are noncontact in nature, 2,3 with landing and plant-and- cut maneuvers being the most common activities associated with it. 4 Females participating in sports that involve jump landing and plant-and-cut type activities have a risk level that is 3-8 times greater than that for males during similar activities. 3,4 Anatomical, hormonal, neuromuscular, and biomechanical differences have been suggested to be the major factors that explain this injury bias. 1,5,6

Context:Hop tests are functional tests that reportedly require strength, power, and postural stability to perform. The extent to which a triple-hop distance (THD) test measures each of these characteristics is relatively unknown.Objective:To determine the extent to which the THD predicts performance on clinical measures of power, strength, and balance in athletic individuals.Design:Within-subjects correlational study.Setting:Station-based, preseason screening of athletes.Patients or Other Participants:Forty National Collegiate Athletic Association Division I-AA men's and women's soccer student-athletes (20 women, 20 men; age = 20.0 ± 1.4 years, height = 172.8 ± 9.2 cm, mass = 71.9 ± 8.9 kg).Intervention(s):As part of a comprehensive preseason screening of athletes, participants completed the Balance Error Scoring System (BESS) test, 3 trials each of the THD and vertical jump, and 5 repetitions each of concentric isokinetic quadriceps and hamstrings strength testing at 60°/s and 180°/s. Bivariate correlations and linear regression analyses determined the extent to which THD (cm) predicted each of the strength, power, and balance measures.Main Outcome Measure(s):Maximal vertical jump height (cm), total BESS error scores, and quadriceps (Quad60, Quad180) and hamstrings (Ham60, Ham180) isokinetic maximum peak torque (Nm) at 60°/s and 180°/s, respectively.Results:Triple-hop distance was a strong predictor of vertical jump height, explaining 69.5% of the variance (P < .01). THD also predicted 56.7% of the variance in Ham60 (P < .01), 55.5% of the variance in Ham180 (P < .01), 49.0% of the variance in Quad60 (P < .01), and 58.8% of the variance in Quad180 (P < .01). No relationships between THD and BESS scores were noted.Conclusions:Triple-hop distance is a useful clinical test to predict an athlete's lower extremity strength and power. Although THD was not a predictor of static balance, further research is needed to examine its relationship with more dynamic balance tests.

We examined the capabilities of the Vermont Knee Laxity Device (VKLD) in measuring varus (VR)-valgus (VL) and internal (INT)-external (EXT) rotational laxities by quantifying measurement consistency and absolute measurement error (N = 10). Based on the expected measurement error, we then examined side-to-side differences (N = 20). For all measures, the knee was flexed 20 degrees , the thigh securely fixed, and counterweights applied to the thigh and shank to create an initial zero shear and compressive load across the tibiofemoral joint. A 10-Nm torque was applied to the knee for VL and VR during non-weight-bearing, and a 5-Nm torque was applied for INT and EXT during non-weight-bearing and weight-bearing conditions. Position sensors measured angular displacements (deg). Except for INT during weight bearing, measurement consistency was good to excellent (range, 0.68-0.96), with absolute measurement errors generally less than 2 degrees for VR-VL and 3-4 degrees for INT-EXT. Although side-to-side differences were observed, they did not exceed absolute measurement errors. The VKLD yields reliable measures of VR-VL and INT-EXT laxities, with sufficient measurement precision to yield clinically relevant differences.

We examined sex differences in general joint laxity (GJL), and anterior-posterior displacement (ANT-POST), varus-valgus rotation (VR-VL), and internal-external rotation (INT-EXT) knee laxities, and determined whether greater ANT and GJL predicted greater VR-VL and INT-EXT. Twenty subjects were measured for GJL, and scored on a scale of 0-9. ANT and POST were measured using a standard knee arthrometer at 133 N. VR-VL and INT-EXT were measured using a custom joint laxity testing device, defined as the angular displacements (deg) of the tibia relative to the femur produced by 0-10 Nm of varus-valgus torques, and 0-5 Nm of internal-external torques, respectively. INT-EXT were measured during both non-weight-bearing (NWB) and weight-bearing (WB = 40% body weight) conditions while VR-VL were measured NWB. All laxity measures were greater for females compared to males except for POST. ANT and GJL positively predicted 62.5% of the variance in VR-VL and 41.8% of the variance in WB INT-EXT. ANT was the sole predictor of INT-EXT in NWB, explaining 42.3% of the variance. These findings suggest that subjects who score higher on clinical measures of GJL and ANT are also likely to have greater VR-VL and INT-EXT knee laxities.

Females have an increased incident rate of anterior cruciate ligament tears compared to males. Biomechanical strategies to decelerate the body in the vertical direction have been implicated as a contributing cause. This study determined if females would exhibit single leg landing strategies characterized by decreased amounts of hip, knee, and ankle flexion resulting in greater vertical ground reaction forces and altered energy absorption patterns when compared to males.Recreationally active males (N=14) and females (N=14), completed five single leg landings from a 0.3m height onto a force platform while three-dimensional kinematics and kinetics were simultaneously collected.Compared to males, females exhibited (1) less total hip and knee flexion displacements (40% and 64% of males, respectively, P0.05) and less time to peak hip and knee flexion (48% and 78% of males, respectively, P0.05), (2) 9% greater peak vertical ground reaction forces (P0.05), (3) less total lower body energy absorption (76% of males, P0.05), and (4) 11% greater relative energy absorption at the ankle (P0.05).Females in this study appear to adopt a single leg landing style using less hip and knee flexion, absorbing less total lower body energy with more relative energy at the ankle resulting in a landing style that can be described as stiff. This may potentially cause increased demands on non-contractile components of the lower extremity. Preventative training programs designed to prevent knee injury may benefit from the biomechanical description of sex-specific landing methods demonstrated by females in this study by focusing on the promotion of more reliance on using the contractile components to absorb impact energy during landings.

Although leg spring stiffness represents active muscular recruitment of the lower extremity during dynamic tasks such as hopping and running, the joint-specific characteristics comprising the damping portion of this measure, leg impedance, are uncertain. The purpose of this investigation was to assess the relationship between leg impedance and energy absorption at the ankle, knee, and hip during early (impact) and late (stabilization) phases of landing. Twenty highly trained female dancers (age = 20.3 ± 1.4 years, height = 163.7 ± 6.0 cm, mass = 62.1 ± 8.1 kg) were instrumented for biomechanical analysis. Subjects performed three sets of double-leg landings from under preferred, stiff, and soft landing conditions. A stepwise linear regression analysis revealed that ankle and knee energy absorption at impact, and knee and hip energy absorption during the stabilization phases of landing explained 75.5% of the variance in leg impedance. The primary predictor of leg impedance was knee energy absorption during the stabilization phase, independently accounting for 55% of the variance. Future validation studies applying this regression model to other groups of individuals are warranted.

We examined the relationship between anterior knee laxity (AKL), evaluated while the knee was nonweight bearing, and anterior translation of the tibia relative to the femur (ATT), evaluated when the knee transitioned from nonweight-bearing to weight-bearing conditions in response to an applied compressive load at the foot. Twenty subjects with normal knees (10 M, 10 F; 25.2 +/- 4.1 years, 169.8 +/- 11.5 cm, 71.6 +/- 16.9 kg) underwent measurements of AKL and ATT of the right knee on 2 days. AKL was measured at 133N with the KT-2000. ATT was measured with the Vermont Knee Laxity Device and electromagnetic position sensors attached to the patella and the anteromedial aspect of the proximal tibia. Three trials for each measure were averaged and analyzed. Measurement consistency was high for both AKL (ICC = 0.97; SEM = 0.44 mm) and ATT (ICC = 0.88; SEM = 0.84 mm). Linear regression revealed that AKL predicted 35.5% of the variance in ATT (p = 0.006), with a prediction equation of Y(ATT) = 3.20 + 0.543(X(AKL)). Our findings suggest that increased AKL is associated with increased ATT as the knee transitions from nonweight-bearing to weight-bearing conditions. The potential for increased knee joint laxity to disrupt normal knee biomechanics during activities such as landing from a jump, or the foot strike phase of gait deserves further study.

This study aimed to determine whether absolute sex hormone concentrations predict the magnitude of knee joint laxity changes across the menstrual cycle. Twenty-two females (18-30 years, body mass index

Objective: To compare the effect of knee angle on muscle response times and neuromuscular recruitment patterns between sexes following a perturbation in single leg stance at 10°, 20°, and 30°. We hypothesized that response times would be faster at lesser knee flexion angles and that females would recruit their quadriceps faster than males at all angles. Design: A repeated-measures design. Setting: Motion analysis laboratory. Participants: Twenty (10 female; 10 male) healthy, recreationally active volunteers. Interventions: A rotary perturbation in single leg stance. Outcome Measurements: Response times of the medial and lateral quadriceps, hamstrings, and gastrocnemius. Results: There was a trend toward faster response times for all muscles closer toward extension. A consistent neuromuscular recruitment pattern for both males and females was evident for each knee angle tested. Females, however, contracted their quadriceps faster than males at all knee flexion angles. Conclusions: Small changes in knee angle near extension do not alter muscle response times and hence neuromuscular recruitment patterns in males and females. Regardless of knee flexion angle, following a perturbation in single leg stance, females contract their quadriceps faster than males. Clinical Relevance: Earlier contraction of the quadriceps in females may increase anterior tibial translation and hence anterior cruciate ligament strain, thereby heightening injury risk.

Sudden changes in direction on a single weight-bearing-limb are commonly associated with injury to the lower extremity. The purposes of this study were to assess the between day reliability of hip, knee, and ankle kinematic displacements achieved with internal and external femur-on-weight-bearing-tibia rotation perturbations and to determine the effect of these perturbations on three dimensional hip, knee and ankle kinematics.Twenty recreationally active, healthy college students with no history of significant orthopedic injury (10 male, 10 female) were subjected to a forward and either internal or external rotary perturbation of the trunk and thigh on the weight-bearing-tibia while three dimensional kinematics were simultaneously collected. The protocol was repeated 24-48 h later to assess reliability.External perturbations resulted in significant internal rotation (IR) of the tibia on the femur (mean 7.3 (SD 3.9 degrees)) and IR of the femur on the pelvis (mean 6.8 (SD 5.4 degrees)) (P0.05). Internal perturbations resulted in significant external rotation (ER) of the tibia on the femur (mean 6.8 (5.9 degrees)) and ER of the femur on the pelvis (mean 10.7 (SD 96.1 degrees)) (P0.05). Additionally the external perturbation results in a significantly greater knee valgus (mean 3.6 (SD 2.2 degrees)) position while the internal perturbation results in a significantly greater knee varus position (mean 2.3 (SD 3.5 degrees)) (P0.05). External perturbation hip and knee total joint displacements revealed moderate to strong reliability (Intraclass Correlation Coefficient(2,k)=0.67-0.94) while internal perturbations revealed slightly higher Intraclass Correlation Coefficients(2,k)(0.80-0.96).The lower extremity perturbation device provides a consistent external and internal perturbation of the femur on the weight-bearing-tibia. The observed transverse and frontal plane kinematics are similar to motions observed during cross-over and side-stepping tasks.

Objective:To determine the relationship between weight-bearing (WB) and non-weight-bearing (NWB) joint reposition sense (JRS) and a functional hop test (FH) and to compare performance on these parameters between athletes and nonathletes.Design:Repeated-measures ANOVA and Pearson correlations.Setting:Research laboratory.Participants:40 men (age = 20.8 ± 1.7 y; ht = 176.9 ± 5.8 cm; wt = 82.6 ± 9.5 kg): 20 lacrosse players and 20 nonathletes.Main Outcome Measures:Ability to actively reproduce 30° of knee flexion in the WB and NWB conditions and functional performance on a single-leg crossover-hop test.Results:No significant correlations were observed between JRS and FH in athletes and nonathletes. No significant differences were observed between athletes and nonathletes in JRS. All participants were significantly more accurate at WB than at NWB JRS.Conclusions:There appears to be no relationship between WB or NWB JRS and functional performance, regardless of one’s physical activity level

This study investigated the effects of isotonic and isometric knee extension exercises on strength, power, and surface EMG in male and female populations. Using the knee extensors, ten males and ten females performed a 120 s MVIC and 120 maximal isotonic contractions. Prior to each exercise (t = pre) knee extensor isometric peak torque (strength) and average peak power (power) were tested utilizing three, 3 s MVIC’s and three maximal isotonic contractions, respectively. Following each exercise, strength and power were assessed immediately after (t =: 00) and at 2.5 (t =: 02.5), 5 (t =: 05), 10 (t =: 10), and 15 (t =: 15) minutes. All strength and power measures were normalized to the respective t = pre value. Vastus lateralis surface EMG signals were collected during all muscle testing and normalized to the respective tire value. Following isometric exercise, both strength and power at t =: 00 (68.7% ± 8.7% & 88.0% ± 8.7%) and t =: 02.5 (82.2% ± 17.8% & 95.2% ± 5.0%) significantly decreased from t=pre (100% ± 0.0%) (p < 0.05) with greater decreases in strength at each time point (p < 0.05). EMG analysis revealed a significant EMG amplitude decrease (p < 0.05) at t =: 00 and t =: 02.5 during strength testing with respect to t=pre. Following isotonic exercise, both strength and power at t =: 00 (68.0% ± 13.2% & 38.8% ± 10.7%) and t =: 02.5 (84.5% ± 14.9% & 81.6% ± 14.5%) significantly decreased from t=pre (100% ± 0.0%) with a greater power decrease at t =: 00 (p < 0.05). The EMG amplitude of males was significantly less at t =: 00 than the respective EMG amplitude for females (p < 0.05) (irrespective of testing condition). We conclude that muscle performance in the fatigued state is dependent upon the type of exercise performed.

Purpose: The purpose of this study was to determine if surface electromyography (EMG) could be used to index fatigue during isotonic and maximal voluntary isometric contractions (MVIC) of the knee extensors in men and women. Methods: Ten males (age = 22.1 ± 3.3 yr, ht = 180.3 ± 5.5 cm, mass 78.7 ± 5.1 kg) and ten females (age = 23.9 ± 4.6 yr, ht = 163.7.3 ± 11.1 cm, mass 63.2 ± 7.4 kg) underwent one isometric (120 s MVIC of the knee extensors) and one isotonic (120 maximal effort isotonic contractions at a resistance of 25% of the MVIC peak torque determined on the testing day) exercise session separated by at least 48 hrs. The EMG signal was collected from the vastus lateralis during both exercise protocols using standard EMG collection techniques. Average torque (AT) was calculated from each 3 s window of the 120 s MVIC, and the average peak power (APP) was calculated for every 3 consecutive contractions during the dynamic exercise. Results: Both the isometric and isotonic fatigue protocols resulted in significant (p 0.05). A main effect for gender (p < 0.05) revealed larger EMG amplitude for females when compared to males during isotonic exercise. Conclusions: These results indicate that gender may be a factor in the development of dynamic fatigue and that EMG can index fatigue during a sustained MVIC.

The purpose of this study was to examine the effects of a resistive tubing kick training protocol on postural sway in uninjured collegiate wrestlers. An experimental group (n = 10) performed a progressive resistive tubing kick training protocol three times per week for 6 weeks. A control group (n = 9) performed no resistive tubing training during the 6 weeks. Postural sway (stability index) was assessed before and after the 6-week training period. ANOVAs demonstrated no significant interactions, although significant main effects were found for group and eye condition. The experimental group demonstrated less postural sway than the control group regardless of training, and postural sway was greater with the eyes closed than with the eyes open. Resistive tubing kick training does not significantly improve postural sway in healthy collegiate wrestlers. Further research should examine the potential benefits of proprioceptive training using a greater intensity of training and/or using subjects who have a greater potential for improvement.

A case of tarsal tunnel syndrome in a male collegiate lacrosse player is presented. The subject reported symptoms consistent with tarsal tunnel syndrome following two incidents of medial ankle sprain in one lacrosse season. Conservative treatment was successful following the first ankle sprain but failed to relieve pain and paresthesia in his heel and medial arch following the second injury. Laboratory tests provided an inconclusive diagnosis, and the subject underwent a retinacular release 5 months after the second ankle sprain. Following a 13-week rehabilitation program, the subject returned to full participation in his sport.

In this study, joint reposition sense of the knee in a non-weight-bearing (NWB) state and that in a weight-bearing (WB) state were compared, and it was determined whether a significant relationship existed between knee displacement (KD) and joint reposition sense. The dominant knees of 8 male and 12 female subjects (age 19–26 years, M ± SD = 21.5 ± 2.06) who had no previous history of knee dysfunction were tested for accuracy of angular reproduction in the WB and NWB states. There was a significant difference in the accuracy of angular repositioning between the two conditions, with the WB test having less deviation from the predetermined angle. There was a weak relationship between KD and the ability to reproduce specific angles of the knee. These results suggest that the WB or closed chain state of the knee was more accurate in the determination of joint position sense than the NWB or open chain condition.

The purpose of this study was to determine how isokinetic eccentric and concentric peak torque/body weight ratios and time to peak torque values relate to drop vertical jump heights in 30 healthy subjects (12 men and 18 women, age = 22.7±2.2 yr, ht =169.6±8.0 cm, wt =67.2f11.9 kg). Drop vertical jumps were performed from a box 50 cm high. Subjects were tested isokinetically on each leg for the motions of knee extension and ankle plantar flexion. Eccentric and concentric peak torque (PT)/body weight ratios along with time (s) to eccentric and concentric peak torque were extracted from the Kin Com II computer. A stepwise multiple regression analysis was conducted to determine the relationship between the eight predictor variables and drop vertical jump height. Knee extension concentric PT/body weight ratio was the most significant predictor of drop vertical jump height, accounting for 23% of-the variance. This finding suggests that the stretch-shortening cycle can be simulated using isokinetic strength measurements and that drop vertical jump height can be attributed in part to concentric knee extension strength.

The purpose of this study was to assess the effect of interferential current (IFC) on perceived pain and serum Cortisol levels in subjects with delayed onset muscle soreness (DOMS). DOMS was induced in 10 subjects through repeated eccentric contractions of the elbow flexors. Forty-eight hours later subjects were evaluated. Starting at t = 0:00, blood samples were withdrawn from a superficial vein every 5 min for 65 min. At t = 0:05, subjects received IFC of 10 bps or IFC of 100 bps. Perceived pain levels were evaluated prior to catheter insertion and at t = 0:35, 0:50, and 0:65. Two mixed-model analyses of variance revealed a significant decrease in perceived pain scores across time for both treatment groups but no significant difference in serum Cortisol for the two groups. It was concluded that IFC of high and low beat frequency is effective in controlling the pain of DOMS but does not elicit a generalized stress response as indexed by increasing serum Cortisol levels.

This study evaluated a visual analog scale (VAS) and a graphic rating scale (GRS) for the measurement of pain following delayed onset muscle soreness (DOMS) and following treatment for the symptoms of DOMS. Data from two studies were used to evaluate the scales. Pain intensity was assessed prior to and following induction of DOMS and immediately before and after each treatment session. In Study 1, subjects were randomly assigned to receive a 20-min ice pack followed by a 7-min sham ultrasound treatment or a 20-min ice pack followed by a 7-min nonthermal ultrasound treatment. In Study 2, subjects received a 20-rain microcurrent neuromuscular stimulation (MENS) treatment or a 20-min sham MENS treatment. In both studies, significant differences were found between the VAS and GRS scales for pretest conditions on Days 1 and 2 for all subjects. There were no significant differences between any other days or tests. The differences on Day 1 and Day 2 were attributed to the novelty of filling out the scales. Therefore, a. visual analog or graphic rating scale can be used to evaluate pain intensity following DOMS when repeated measurement is involved, although consideration should be given to potential differences the first one or two times the scales are completed.

Aging is associated with decreases in strength and muscle mass. In addition, the ability to maintain balance decreases with age. Few studies have examined the relationship between isokinetic muscle performance and balance performance. It was the purpose of this study to determine if there is a relationship between muscle and balance performance, and to discover how this relationship is affected by age. Fifty-five healthy females were recruited from two different age groups, 28 females who were 18-30 years of age {mean age = 22.9 years ( ± 3.4), height = 163.5 cm (±6.5), weight = 64.8 kg (± 15.7)) and 26 females who were > 60 years of age {mean age = 68.1 years (+ 4.8), height = 159.7 cm (± 10.0), weight = 68.0 kg (± 11.4)1. Concentric and eccentric isokinetic muscle performance for the hip, knee, and ankle was measured using the KinCom isokinetic dynamometer. Balance performance was measured using the sharpened Romberg and one-legged stance tests. Younger subjects performed significantly better than older subjects on all muscle and balance performance variables (P = 0.05 to P = 0.0001), except the sharpened Romberg test with the eyes open. The older group exhibited significant relationships between balance and muscle performance measures (r — 0.10 to r — 0.57). In the older group, hip muscle performance was shown to correlate significantly better with balance performance than knee or ankle muscle performance. Also noted was a significantly greater relationship between muscle performance and balance performance with the eyes closed in the older group, as compared to the younger group. This is the first study known to thoroughly examine the relationship between muscle and balance performance. The presence of significant relationships warrants further examination. It is recommended that this relationship be examined in a broad spectrum of young, old, healthy and disabled populations.

The purpose of this study was to investigate the effects of induced anesthesia of the lateral ankle joint on proprioception as assessed in weight-bearing and non-weight-bearing conditions. Sixteen subjects were assessed under normal conditions and following an 8-cc injection of lidocaine into the anterior talofibular ligament of the ankle being tested. Center of balance and postural sway measurements were analyzed, revealing a significant lateral adjustment of center of balance during the stable tests compared to a medial adjustment during the dynamic tests under the anesthetized condition. ANOVA of postural sway scores revealed no main effect for condition (anesthesia vs. no anesthesia), but sway scores were higher during the two dynamic conditions as compared to the stable condition. ANOVA of joint position error scores revealed no main effect for condition. Findings suggest that inhibition of the joint receptor afferent fibers adversely affected joint proprioception as assessed while subjects were weight bearing but not while they were non-weight bearing.

Returning athletes to competition following injury often creates a dilemma for athletic trainers and team physicians. Most clinicians gather as much data as possible before deciding whether to return an athlete to competition following injury. The status of the postural control system and balance is important for certain pathologies and therefore should be considered in these clinical decisions. As more high-tech balance systems become available, it is important for clinicians to understand not only what is available but what these devices measure. This paper will review the relationship between the postural control system and the kinetic chain, traditional and contemporary techniques for assessing balance, and ways in which clinicians can bridge the gap between balance research and clinical practice.

The influence of cutaneous and joint receptors on the quadriceps femoris torque-velocity relationship was assessed with the Kin-Com (Chattecx, Inc., Hixson, TN) isokinetic dynamometer. Twenty-four females (age = 21 ± 1.4 years, ht = 163 ± 6.0 cm, wt = 60 ± 7.6 kg) were divided into two groups and tested with the force pad placed either proximally or distally on the leg. Three concentric and eccentric contractions were performed at 25, 50, 75, 100, 125, 150, 175 and 200 0 s -Ion 2 separate days with an anesthetic applied to the skin under the force pad on 1 of the 2 days. An ANOYA was performed on peak torque with trend analyses performed on velocity factors. The results indicate the cutaneous and knee joint receptors do not affect the quadriceps femoris concentric or eccentric torque-velocity relationships, F(7, 154) = 1.6~. Furthermore, the results revealed significant linear, F(1, 154) = 161.14, and quadratic trends, F(1, 154) = 25.85, for concentric and eccentric peak torque, respectively. Thus, the concentric torque-velocity relationship is best described by a linear relationship rather than the classic curvilinear relationship. Conversely, the eccentric relationship is best described by the classic curvilinear relationship. These results suggest that adequate assessment of muscular torque production requires testing at multiple velocities.

This study examined the effect of cold treatment on the force-velocity relationship of the quadriceps muscle of 16 athletes. Each subject performed three maximal concentric and eccentric quadriceps contractions on the Kin-Com at 25, 50, 75, 100, 125, 150, 175 and 2000s -I. On one of two testing sessions, subjects received a 20 min ice application prior to testing, and for the remaining session, no ice was applied. The results revealed no significant change in the torque-velocity relationship. A trend analysis revealed linear relationships for the concentric ice [F 0,15) = 82.23] and no ice [F 0,15) = 44.86] conditions as well as for the eccentric ice [F 0,15) = 38.58] and no ice [F (1,15) = 26.40] conditions. There were no significant differences between the concentric ice and no ice means at any velocity, but peak torque at 2000s -I was significantly different from peak torque at 25-1000s -I. For eccentric contractions there was a difference between ice and no ice means, with an increase of 20% and 16% for the ice condition at 175 and 2000s -I, respectively. For the eccentric ice conditions across velocities, the PT at 2000s -I was significantly different from the PT at 125-2000s -I. This suggests that the application of ice will not decrease strength but may in fact result in an increase in eccentric strength.

The purpose of this study was to estimate intertester reliability of active and passive ankle joint position sense measurements in uninjured subjects. Subjects were 10 males and 10 females. Active and passive ankle joint position sense was assessed by two testers. Each subject was positioned supine on a modified examination table with his or her ankle placed in 25° of plantar flexion. Joint position sense (IPS) measurements, on two separate occasions, were recorded in degrees of error from four predetermined test positions. Test order was counterbalanced according to mode (active/passive) and test position. Two trials were performed for each sequence and the average of the two was recorded for analysis. The results revealed that both the active and passive JPS protocols yielded poor to moderate intertester reliability. It was concluded that further research is needed to develop reliable protocols for testing joint position sense of the ankle joint.

This study evaluated the effectiveness of ibuprofen in treating delayed onset muscle soreness (DOMS) of the elbow flexors when taken prior to and following exercise. Twenty subjects received either 2,400 mg/day ibuprofen or a placebo four times per day. Subjects performed intense eccentric exercise of the elbow flexors to elicit DOMS. Concentric and eccentric peak torque production against an isokinetic resistance of 0.52 radls, range of motion at the elbow, and subjective soreness of the elbow flexors were measured. ANOVA indicated no significant group-by-time interaction for concentric peak torque, eccentric peak torque, or pain. A significant interaction was revealed for range of motion. There was a significant difference within each group's ROM but no interaction between groups. It was concluded that the use of 2,400 mg/day ibuprofen prior to and following intense eccentric exercise was no more effective than a placebo in treating DOMS of the elbow flexors.

This study examined the test-retest reliability of a prototype device used to measure ankle inversion and eversion isokinetic average torque values. The purpose of this paper was to illustrate a situation where common isokinetic measures were reliable but not valid. Concentric and eccentric average torque was assessed at 90 deg/s on the Kin Com II dynamometer using 14 healthy subjects in two sessions; a manufactured prototype ankle inversion/eversion attachment device was used. Reliability was assessed by performing separate intraclass correlations (ICC 2,1) on the results. The data indicated that the average torque calculated from the clockwise direction was consistently higher than those values from the counterclockwise direction, regardless of ankle movement or side measured. The validity of this prototype device to accurately measure average torque for these two ankle motions is questionable. This finding demonstrates a situation where the measures appear to be reliable while the validity of the device used to obtain the measures is suspect.

Using the Kin-Com (Chattecx Corp, Hixson, TN) isokinetic dynamometer, 20 university females (age = 21.6 ± 1.4 years, wt = 61.73 ± 7.3 kg, ht = 162.81 ± 5.8 cm) performed concentric and eccentric isokinetic contractions at nine different velocities. At each velocity, subjects performed two submaximal and one maximal concentric and eccentric familiarization contractions. Three alternating concentric and eccentric maximal contractions followed a 1-min rest between the familiarization and maximal contractions. One minute of rest was also provided between the test contractions and the next set of familiarization contractions. The peak torque (PT) and average torque (AT) for the first and ninth set of contractions were analyzed with separate repeated measures ANOVAs. The results demonstrated no significant differences for the interaction or for the test main effect for either PT or AT. This suggests that with appropriate rest intervals, as many as 96 submaximal and maximal concentric and eccentric contractions can be performed without fatigue affecting assessment of PT and AT.

The purpose of this study was to determine the reliability of the Kinetic Communicator's (Kin-Com) gravity correction procedure. To determine mechanical reliability, gravity correction was performed at 11 different angles while weights (1.15, 2.30, 3.45 and 4.60 kg) were suspended from the lever arm. Intraclass correlation (ICC) between trials showed that the Kin-Com was able to gravity correct weights with high reliability (R = 0.961-0.999). Gravity correction values from the 11 angles were analyzed with a one-way analysis of variance with repeated measures to determine if differences existed between gravity correction values collected at different angles for each weight condition. Even though reliability was good for each angle, gravity correction values collected near the vertical position differed from the gravity correction values collected at the horizontal position (P < 05). Differences decreased as weight increased. To determine clinical reliability, 25 subjects (age = 21.0 years, height = 16.6 cm, weight = 59.8 kg) were also gravity corrected in both the seated and prone positions at six different angles on 2 separate days. Correlation analysis between days showed good reliability (R = 0.83) for both positions when subjects were corrected at the horizontal. Reliability decreased as the lever arm approached vertical. Differences between gravity correction values existed at every angle measured for both positions. Even though the gravity correction was shown to be reliable at positions other than the horizontal, gravity correction should be performed at the horizontal position each time subjects are assessed.

Various devices and test protocols have been used during isokinetic assessment of human muscle performance. The purpose of this investigation was to examine the effects of continuous and interrupted test protocols and test device on concentric quadriceps peak torque (PT) production. PT was measured via two commonly employed isokinetic test devices (Cybex II and Kin-Corn) and test protocols (interrupted (1) and continuous (C)). Thirty-one. male subjects ( x age 23.0 ± 2.07 years, x wt 78.2 ± 12.2 kg, x ht 177.8 ± 6.45 cm) were tested at 1.08 rad/s (60°/second), 48 h apart on each device in random order. Because the devices correct for gravity differently, gravity correction was eliminated from all test conditions. Preload and damp were applied in order to replicate clinical protocols as closely as possible. Intraclass correlation coefficients (2,3) (and standard errors of measurement) were 0.88(7.52 N , m) (I) and 0.91 (7.04 N , m) (C) for the Kin-Corn, and 0.98 (3.30 N , m) (I) and 0.92 (8.42 N. m) (C) for the Cybex. A 2 x 2 within subjects ANOVA demonstrated significant differences between Cybex (damped) and Kin-Corn (preload) PT measures (P 5 0.05). An interaction for device x protocol demonstrated greater peak torque values for the I protocol (Kin-Corn: 199.1 ± 44.9 N. m, Cybex: 181.7 ± 35.0 N .m) than for the C protocol (Kin-Com: 182.2 ± 35.5 N m, Cybex: 183.3 ± 33.9 N -m) (P < 0.05) for the Kin-Com although the Cybex values were the same. Although both the interrupted and continuous protocols demonstrate high reliability, the interrupted protocol results in higher quadriceps PT values for the Kin-Com. We conclude that selection of test protocol influences assessment of quadriceps PT when using the Kin-Com isokinetic dynamometer.

Background: Anterior cruciate ligament (ACL) injuries often occur during landing, with female athletes at higher injury risk than male athletes. Interestingly, female dancers have lower ACL injury rates than do female athletes in general. Hypothesis: Female dancers will have earlier and greater lower extremity muscle activity and higher sagittal knee joint and leg stiffness than will female basketball players. Study Design: Cross-sectional group comparison. Methods: Fifty-five healthy female athletes (35 dancers, 20 basketball players) performed 5 double-leg drop jumps from a 45-cm box. Surface electromyography (onsets and amplitudes; prelanding and postlanding) was recorded from the lateral gastrocnemius, medial and lateral hamstrings, lateral quadriceps muscles with a 3-dimensional electromagnetic tracking system, and forceplates recording biomechanics (leg spring stiffness and knee joint stiffness). Results: Compared with basketball players, dancers had greater leg spring stiffness ( P = 0.047) but similar knee joint stiffness ( P = 0.44). Although no significant differences were observed in overall muscle onset times ( P = 0.22) or activation amplitudes (prelanding, P = 0.60; postlanding, P = 0.78), small to moderate effect sizes (ESs) suggest trends in dancers toward earlier (ES = 0.53) and higher medial hamstrings activation pre- (ES = 0.55) and post- (ES = 0.41) landing and lower lateral quadriceps (ES = 0.30) and higher gastrocnemius (ES = 0.33) postlanding muscle activation. Conclusions: In dancers, the higher leg spring stiffness and trends toward higher hamstrings prelanding and postlanding, as well as lower quadriceps and higher gastrocnemius activation postlanding with similar knee joint stiffness, indicate lower extremity neuromechanical differences across other joints. Clinical Relevance: Female dancers may have lower extremity neuromechanics that are different from those of basketball players during drop jumps. If dancers use ACL-protective strategies during activity, then their training routines should be further investigated to improve ACL injury prevention programs.

The purpose of this study was to assess anterior translation of the tibia using the Tibial Fixator Device (a mechanical leg stabilizer that controls tibial alignment) with the leg in three positions: neutral (N), internal rotation of 15° (IR), and external rotation of 15° (ER). Displacement was measured using a modified KT-1000 arthrometer. Eleven subjects with anterior cruciate ligament lesions were examined bilaterally in the three positions at 45, 67, and 89 newtons of anterior force. Three-factor repeated-measures ANOVA revealed a significant position effect regardless of force (p < .001). This effect was significant in the injured and noninjured legs. Displacement was greatest in ER and least in IR. These data indicate that the position of the tibia, maintained with an external leg restraint, has a significant effect on anterior displacement of the knee. Control of tibiofemoral alignment and modifications to the KT-1000 provide new potentials for instrumented arthrometry.

•The purpose of this investigation was to determine the effect of test protocol on concentric and eccentric torque production of the rotators of the shoulder. Twenty­ eight female subjects were randomly assigned to participate in either a continuous (no pause between concentric and eccentric contractions) or interrupted (5-second pause between contractions) measurement protocol. A Kin-Com dynamometer (Chattecx Corp., Hixson, TN) was used to obtain average torque measurements at 60 and 180 deg/sec for the shoulder rotators. Analysis of variance determined that there were no significant (p > 0.05) differences in average torque between test protocols for either muscle group. Intraclass correlation coefficients (ICCs) ranged from 0.57 to 0.88 for the continuous protocol and from 0.83 to 0.94 for the interrupted protocol. Standard error of measurement estimates ranged from 0.7 to 1.5 Nm for the continuous protocol and from 0.5 to 1.4 Nm for the interrupted protocol. The results of this investigation demonstrate no differences in torque production between continuous and interrupted test protocols, although the interrupted measurement protocol provides greater reliability and precision of measurement

Medial elbow injuries of athletes, such as baseball pitchers and javelin throwers, can prove to be debilitating and may have a negative effect on performance. The most significant injury to the elbow occurs is an ulnar collateral ligament (UCL) sprain or rupture, which compromises the medial stability of the elbow joint. It has been found that the anterior oblique portion of the UCL is the primary stabiliser of the elbow, and that trauma to this complex may significantly hinder normal elbow function. An accurate diagnosis will dictate the degree of injury to the elbow as well as determine the most appropriate means of treatment.

This paper reviews the concepts associated with isokinetic open chain assessment and exercise of the quadriceps and hamstring muscle groups. Following a review of the isokinetic concept of exercise, the paper addresses principles of assessment and exercise of the knee, including the importance of musculoskeletal and cardiovascular screening, warm-up, body position, stabilization, and joint alignment. Gravity correction, test and exercise velocity, and duration of exercise are also addressed. Interpretation of an isokinetic evaluation of the knee is also addressed within the context of force-velocity relationships, peak torque relative to body weight, and bilateral and reciprocal muscle group relationships. Joint range of motion and test velocity are also discussed with respect to patellofemoral and tibiofemoral joint forces. Finally, recommended protocols for isokinetic assessment and exercise of the quadriceps and hamstring muscle groups are presented.

The purpose of this study was to determine whether external compression would cause a decrease in the isokinetic muscular endurance of the quadriceps and hamstring muscle groups. Subjects were tested on the Cybex II dynamometer (Cybex, Ronkonkoma, NY) under two conditions: with external compression applied to the thigh and without external compression applied to the thigh. External compression was applied with a lower extremity blood pressure cuff inflated to a predetermined clinically standardized pressure. The subjects performed an isokinetic endurance test consisting of 30 maximal repetitions at 180 deg/sec under both conditions. A paired t test showed no statistical differences (p > 0.05) between the mean total work, work over the first five repetitions, and work over the last five repetitions between the two conditions for the quadriceps and the hamstring muscle groups. Results indicated that external compression applied to the thigh at 30 mm Hg caused no significant decrease in the isokinetic muscular endurance of the quadriceps or hamstrings. Further research is indicated to determine whether external compression could influence other aspects of muscular performance.

Nineteen patients with the clinical diagnosis of anterior cruciate ligament injury were examined by KT-1000 ar thrometry before arthroscopy in an effort to differentiate partial from complete tears. To this end, the KT-1000 arthrometer was equipped with a strain gauge and pro cessor that permitted the required force to increase the anterior displacement by 1-mm increments, to be read on a light-emitting diode. The measured force has been plotted against anterior displacement expressed in non linear increments along the x-axis to allow for the vis coelastic nature of the ligament. The results show that stress-strain diagrams of partially torn and completely torn ligaments are similar to those obtained by graded stress radiography. Using arthroscopy as the standard of measurement, partial tears can be differentiated from complete tears with a sensitivity of 80% and a specificity of 100%. The figures for complete tears versus partial tears are 100% and 80%, respectively. Graded arthrom etry with x-y recording of the force-displacement rela tionship that allows for the viscoelastic qualities of liga ment further extends the capabilities of instrumented arthrometry.

This study examined the effect of the Swede-O ankle brace on talar tilt in subjects with unstable ankle joints. Six college-age females with talar tilts greater than 9.5° at 15 decaNewtons (daN) of force on a Telos stress test device participated in the study. Each subject was X-rayed at five levels of force (0,6,9, 12, and 15 daN), first with a bare ankle then wearing a Swede-O ankle brace. A two-factor (Brace × Force) analysis of variance revealed a main effect for force, but no main effect for brace and no Brace × Force interaction. For the unbraced ankles, mean displacements were 8.2, 10.4, 11.9, and 13.1° at the four levels of force, respectively. After application of the brace, the talar tilts were 5.7, 8.5, 11.1, and 12.8°, respectively. These findings suggest that the Swede-O ankle brace was not effective in reducing talar tilt in subjects with unstable ankles. Any efficacy of the brace may be due to other factors, such as proprioceptive feedback during inversion.

The purpose of this study was to examine the validity of the average and peak torque values of the knee extensor and flexor musculature obtained through the data extraction technique. Twenty women (age = 20.2 ± 1.01 yr; height = 169.0 ± 6.8 cm; weight = 60.8 ± 5.5 kg) were assessed for isokinetic peak and average torque of the knee musculature at a velocity of 90 deg/sec. Subjects were randomly assessed through a range of motion of 5-90 deg and 25-70 deg. Peak and average torque values within a range of motion of 25-70 deg were extracted from the tested range of motion of 5-90 deg. Correlational analyses between the tested and extracted variables revealed relationships ranging from r = 0.79 to 0.95. Paired t tests found no significant differences (p < 0.006). These findings suggest that the data extraction techniques are valid.

The purpose of this investigation was to determine the relationship between ethnicity and acute pain response in male athletes. Subjects included 93 male athletes (age = 18.65 ± .58 years) of differing ethnicity. Each subject performed a Cold Pressor Test (CPT) and was evaluated for pain threshold and pain tolerance times. Two one-way analyses of variance were performed to analyze the data. The results indicated that significant differences existed in pain tolerance times between ethnic groups (p

to better understand how sex differences in anterior knee laxity (AKL) affect knee joint biomechanics, we examined the consequence of greater absolute baseline (males and females) and cyclic increases in AKL during the menstrual cycle (females) on anterior tibial translation (ATT) as the knee transitioned from non-weight-bearing to weight-bearing conditions, while also controlling for genu recurvatum (GR).males and females (71 females and 48 males, aged 18-30 yr) were measured for AKL and GR and underwent measurement of ATT. Women were tested on the days of their cycle when AKL was at its minimum (T1) and maximum (T2); males were matched in time to a female with similar AKL. Linear regressions examined relationships between absolute baseline (AKLT1, GRT1) and cyclic changes (Δ = T2 - T1; AKLΔ, GRΔ) (females only) in knee laxity with ATT as measured at T1 and T2 and Δ (T2 - T1) (females only).AKL and GR increased in females, but not in males, from T1 to T2. Greater AKLT1 and GRT1 predicted greater ATTT1 and ATTT2 in males (R = 21.0, P0.007). The combination of greater AKLT1, AKLΔ, and less GRΔ predicted greater ATTT1 and ATTT2 in females (R = 12.5-13.1, P0.05), with AKLΔ being a stronger predictor (coefficient, P value) of ATTT2 (0.864, P = 0.027) compared with ATTT1 (0.333, P = 0.370). AKLΔ was the sole predictor of ATTΔ (R = 0.104 and 0.740, P = 0.042).greater absolute baseline and cyclic increases in AKL were consistently associated with greater ATT produced by transition of the knee from non-weight-bearing to weight-bearing. Because the anterior cruciate ligament is the primary restraint to ATT, these findings provide insight into the possible mechanisms by which greater AKL may be associated with at-risk knee biomechanics during the weight acceptance phase of dynamic tasks.

The purpose of this investigation was to determine the relationship between personality characteristics, as measured by the Myers-Briggs Type Indicator (MBTI) (form G), and an acute pain response in 107 postadolescent men. Subjects included 107 military school cadets. Each subject performed a cold pressor test (CPT) and was evaluated for pain threshold and pain tolerance times. Each was then evaluated for preference on eight personality characteristics: extraversion, introversion, sensing, intuition, thinking, feeling, judging, and perception. The personality characteristics were measured by the MBTI (form G). Pearson product-moment correlations between the pain threshold and tolerance times and the eight personality characteristic scores were nonsignificant. The results indicated there was no relationship between the eight personality characteristics, as measured by the MBTI (form G), and pain threshold or pain tolerance, as measured by the CPT. The findings also indicated a low correlation between pain threshold and pain tolerance (r=.25). The sensation of pain is basic to all people. It acts as a warning system and alerts a living organism of danger or threat to homeostasis. Monks and Taenzer (14) state than an individual's pain perception is associated with "interrelated biological, psychological, and social factors" (p. 233). Health care professionals are aware of individual differences among the patients they encounter with respect to personality and response to pain. However, these differences are rarely considered when planning treatment protocols. The aspect of personality type and its relation to pain response is an area that has been examined in the past. The literature indicates that personality influences pain response (1, 10, 13, 19). with a focus on extraversion and neuroticism (4, 8, 11, 20). It has been hypothesized that a subject's pain tolerance should be positively related to extraversion and negatively related to neuroticism (5, N. Eysenck (5, 6) postulated that extraverts develop inhibition/satiation more quickly and dissipate it more slowly. As such, prolonged pain sensations should be inhibited more quickly and more strongly in extraverts, leading to diminished pain sensation, Beecher (2) stated that physiological pain is always associated with the apprehension of future pain, which can be conceived as an anxiety response that summates with the physiological pain response, It was further suggested that extraverts condition less well. Therefore they would not develop the component of total pain to the same degree that introverts would. Several investigators have tested the relationship between pain and personality and have reported conflicting findings. Lynn and Eysenck (11) used the Maudsley Personality Inventory (MPI) as a measure of personality, and radiant heat as an acute pain inducer. They reported positive correlations for extraversion and pain tolerance , 0.69 (

David H. Perrin, PhD, ATC* • Evan V. Hellwig, PT, ATC* Laurie L. Tis, MEd, ATC* • Byron S. Shenk, EdDt University of Virginia . ------------------This study examined the effect of gravity correction on concentric and eccentric average force of the right and left side shoulder rotator muscles and on the external/internal rotation reciprocal muscle group ratios. Thirty-three males were tested on a Kinetic Communicator dynamometer at 150 deg/sec from a seated position with the shoulder abducted to 90 deg and positioned along the frontal plane. Gravity correction procedures were followed prior to testing, and both the gravity-uncorrected (GU) and gravity-corrected (GC) values were obtained from the dynamometer's software. Paired t-tests indicated the gravity correction procedure increased every value obtained during external rotation and decreased all values obtained during internal rotation. Also, the concentric and eccentric external/internal rotation reciprocal muscle group ratios were all higher as a result of the gravity correction procedure. These findings were consistent with previous reports on the effect of gravity correction on lower extremity muscle groups. In particular, gravity correction significantly added to the muscle group opposed by gravity (external rotators) and detracted from the muscle group assisted by gravity (internal rotators). Therefore correction for the effects of gravity is recommended during isokinetic assessment of the shoulder internal and external rotator muscle groups.