Open Chain Isokinetic Assessment and Exercise of the Knee

Abstract: This paper reviews the concepts associated with isokinetic open chain assessment and exereise 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. Article: Isokinetic resistance is a dynamic, fixed-velocity, and accommodating-resistance form of exercise. The primary advantage of isokinetic resistance is that a muscle group may be exercised to its maximum potential throughout the knee joint's entire range of available motion. Isokinetic exercise may be used to quantify the quadriceps and hamstring muscle groups' abilities to generate torque or force and is also useful as an exercise modality in the restoration of either muscle group's preinjury level of strength. A comprehensive review of the theory and clinical application of isokinetic exercise and assessment for all major joints of the body may be found elsewhere (16). The knee joint is a modified hinge joint formed by the articulation of the distal femur and proximal tibia. The joint is capable of flexion and extension, and it is modified in the sense that internal rotation and external rotation of the tibia occur in combination with flexion and extension, respectively. Twelve muscles croSS the knee joint with the principle extensors being the quadriceps femoris muscles, consisting of the rectus femoris, and the vasti medialis, intermedius, and lateralis muscles. The primary flexors of the knee include the hamstring muscle group, consisting of the biceps femoris, semitendinosus, an

Translocator protein in late stage Alzheimer\u27s disease and Dementia with Lewy bodies brains

OBJECTIVE: Increased translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), in glial cells of the brain has been used as a neuroinflammation marker in the early and middle stages of neurodegenerative diseases, such as Alzheimer\u27s disease (AD) and Dementia with Lewy Bodies (DLB). In this study, we investigated the changes in TSPO density with respect to late stage AD and DLB. METHODS: TSPO density was measured in multiple regions of postmortem human brains in 20 different cases: seven late stage AD cases (Braak amyloid average: C; Braak tangle average: VI; Aged 74-88, mean: 83 ± 5 years), five DLB cases (Braak amyloid average: C; Braak tangle average: V; Aged 79-91, mean: 84 ± 4 years), and eight age-matched normal control cases (3 males, 5 females: aged 77-92 years; mean: 87 ± 6 years). Measurements were taken by quantitative autoradiography using [ RESULTS: No significant changes were found in TSPO density of the frontal cortex, striatum, thalamus, or red nucleus of the AD and DLB brains. A significant reduction in TSPO density was found in the substantia nigra (SN) of the AD and DLB brains compared to that of age-matched healthy controls. INTERPRETATION: This distinct pattern of TSPO density change in late stage AD and DLB cases may imply the occurrence of microglia dystrophy in late stage neurodegeneration. Furthermore, TSPO may not only be a microglia activation marker in early stage AD and DLB, but TSPO may also be used to monitor microglia dysfunction in the late stage of these diseases

Reliability of isokinetic Measures

Abstract: Isokinetic resistance is frequently used to strength profile healthy athletes and to evaluate the status of injured athletes involved in rehabilitation programs. The purpose of this investigation was to determine the reliability of peak torque, torque acceleration energy, endurance ratio, average power, and total work measures obtained with a Cybex isokinetic dynamometer. Fifteen college students underwent a test -retest procedure for right and left knee flexion and extension, shoulder flexion and extension, and shoulder internal and external rotation. Highest reliability coefficients were found for peak torque, torque acceleration energy, average power, and total work measures. Lower coefficients were observed for the endurance ratio measure. Higher reliability was generally observed for the knee extension/ flexion test procedure than for the shoulder tests. Article: Since the use of isokinetic exercise by Hislop and Perrine (5), Moffroid et al. (10), and Thistle et al. (15), the procedure has received increasing interest in sports medicine research and clinical practice. Its usefulness in research has included examination of the relationship of muscle strength to fiber type and metabolic enzyme activity (16), the effects of training and performance on muscular strength and endurance (7), the influence of limb speed on torque production (12), and the relationship of peak torque to age, sex, performance, and body weight (9, 13). In the clinical setting, isokinetic exercise is used to evaluate the effectiveness of physical rehabilitation and to provide progressive resistance exercise therapy (3, 4). Most clinicians assume that isokinetic dynamometers provide reliable measures of strength, power, and endurance. While some research has proven the reliability of torque measures (1, 6, 10, 11), little attention has been devoted to the reliability of power and endurance measures. The development of a computer' interface with the Cybex apparatus has enabled the precise and rapid isokinetic measurement of peak torque, angle of occurrence of peak torque, average power, total work, torque acceleration energy, and endurance ratio (14). Barbee and Landis (2) assessed the reliability of some of these computer obtained measurements and reported coefficients of r = .91 to .97 for peak torque, r = .86 to .95 for power, r = .85 to .97 for total work, and r = .13 to .27 for torque acceleration energy

The Reliability of Four Different Methods. of Calculating Quadriceps Peak Torque Angle-Specific Torques at 30°, 60°, and 75 °

Twelve university females were studied to determine the reliability of four different methods of calculating concentric and eccentric peak torque (PT) and angle-specific torques (ASTs) for knee extension. Each subject was tested on the Kin-Corn isokinetic dynamometer on two separate occasions, performing five concentric and eccentric contractions at 60° PT and AST at 30°, 60°, and 75° were calculated by averaging the first three contractions, averaging all five contractions, taking the single best value of the first three contractions, and taking the single best value of all five contractions. Intraclass correlation coefficients derived from these calculations showed high correlation among the four methods. Additionally, z tests performed on correlation coefficients transformed to Fisher's Z revealed no differences between pairs of correlation coefficients. These data appear to show there is no difference among the four methods of calculating PT and AST

Effects of cutaneous and joint receptors on the quadriceps femoris force-velocity relationship

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's-1 on 2 separate days with an anesthetic applied to the skin under the force pad on 1 of the 2 days. An ANOVA 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) —1.61. 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

Research and clinical applications of assessing balance

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

Relationship between Selected Physical Characteristics and Functional Capacity in the Anterior Cruciate Ligament-Insufficient Athlete

Traditionally, clinicians have utilized various physical characteristics as criteria to assess the functional status of anterior cruciate ligament (ACL)-insufficient athletes without validating the efficacy of such assessments. The primary purposes of this study were to determine the relationship between traditionally used physical characteristics and functional capacity of individuals with an ACL insufficiency and to compare functional results of two groups of ACL-insufficient athletes. Forty-one subjects were tested for strength and power on an isokinetic device, anthropometric characteristics, and function using three functional performance tests (FPT). Results revealed that conventional physical characteristics correlated poorly (r = .01 to r = .42) with the functional tests. Additionally, athletes who were able to return to preinjury levels of activity performed significantly (p < 0.05) better on the FPT than those who were unable to return to preinjury activities. Based on the results of this study, use of such traditional physical characteristics for predicting function in the ACL-insufficient athlete may be inappropriate, and the functional performance tests designed for this study appear to be the most valuable assessment of the athlete's functional capacity

Alternative approaches to the assessment of mild head injury in athletes

Objectives: Athletic trainers and team physicians are often faced with decisions concerning the severity and timing of an athletes return to play following mild head injury (MHI). These decisions can be the most difficult ones facing clinicians because of the limited amount of quantitative information indicating injury severity. Several authors have published guidelines for return to play following MHI, however these guidelines are based on limited scientific data. The purpose of this paper was to examine the effects of MHI on two objective measures, postural stability and cognitive function, to determine their usefulness in MHI assessment. The data gathered from these two measures has the potential to establish recovery curves based on objective data. Methods: Eleven Division I collegiate athletes who sustained a MHI and eleven matched control subjects were assessed for postural stability and cognitive function at four intervals following injury. Postural stability was assessed using the Sensory Organization Test on the NeuroCom Smart Balance Master. Cognitive functioning was measured through the use of four neuropsychological tests: Stroop Test, Trail Making Test, Digits Span and Hopkins Verbal Learning Test. Separate mixed model repeated measures ANOVAs were calculated for the composite score and three ratio (vestibular, visual and somatosensory) scores from the Sensory Organization Test and the scores from the neuropsychological test to reveal significant differences between groups and across days postinjury. Results: A significant group by day interaction for overall postural stability(composite score) revealed that MHI athletes displayed increased postural instability for the first few days following MHI (p<.05). Analysis of the ratio scores revealed a significant interaction for the visual ratio. No significant group differences were revealed for any of the neuropsychological tests (p<.05), however significant day differences were revealed(p<.05). Conclusions: The results from this study indicate that athletes demonstrate decreased stability until 3 days postinjury. It appears this deficit is related to a sensory interaction problem, whereby the injured athlete fails to use their visual system effectively. These findings suggest that measures of postural stability may provide clinicians with a useful clinical tool for determining when an athlete may safely return to competition, although these findings need to be confirmed in larger groups of athletes

Effect of Orthotics on Postural Sway Following Inversion Ankle Sprain

Orthotic devices have been shown to successfully modify selected aspects of lower extremity mechanics and enhance foot stability during the support phase of running. It was hypothesized that orthotic intervention would relieve excessive strain on the ankle ligaments and reduce postural sway, especially in subjects with acute ankle sprains. The primary purpose of this study was to determine if orthotics would reduce postural sway in injured and uninjured subjects. Thirteen subjects with acute inversion ankle sprains and 12 uninjured subjects were assessed for postural sway on the Balance System under two treatment conditions (orthotic and nonorthotic) and four platform movements. A three-factor repeated measures analysis of variance revealed a significant group x treatment interaction, suggesting that postural sway with orthotic intervention improved significantly more in injured subjects than in uninjured subjects. A significant platform movement x treatment interaction, furthermore, revealed that postural sway for the four movement conditions was dependent upon treatment (orthotic vs. no orthotic). Tukey post hoc analysis revealed that orthotic intervention significantly reduced postural sway when the platform moved in the medial/lateral plane and inversion/eversion plane. This research suggests that custom-fit orthotics may restrict undesirable motion at the foot and ankle and enhance joint mechanoreceptors to detect perturbations and provide structural support for detecting and controlling postural sway in ankle-injured subjects

Assessment of neuromuscular response characteristics at the knee following a functional perturbation

Previous research indicates that both the extent and timing of muscular activation at the knee can be influenced by muscle activity state, joint angle, weight-bearing status and trunk position. However, little research to date has evaluated protective neuromuscular response times and activation patterns to an imposed perturbation with the knee joint in a functional, weight-bearing stance. Hence, we designed a lower extremity perturbation device to produce a sudden, forward and either internal or external rotation moment of the trunk and femur relative to the weight-bearing tibia. Surface electromyography (EMG) recorded long latency reflex times of the medial and lateral quadriceps, hamstring and gastrocnemius muscles in 64 intercollegiate lacrosse and soccer players in response to both internal and external rotation perturbation. We found the gastrocnemius fired significantly faster that the hamstring, which in turn fired significantly faster than the quadriceps. There was also a significant difference in activation times of the medial and lateral hamstring not found for the quadriceps or gastrocnemius muscles. Our findings confirmed that reactive neuromuscular responses following this functional perturbation differ markedly from those previously reported using seated, partial weight-bearing and/or uni-planar models under relaxed conditions