Biomedical subjects

J F Kramer

Publications and source records attributed to J F Kramer.

At least 19 recordsLinked to original sources

PubMed2001

Association among neuromuscular and anatomic measures for patients with knee osteoarthritis.

OBJECTIVE: To investigate neuromuscular and anatomic factors involved in varus gonarthrosis by identifying measures associated with degenerative changes. DESIGN: Descriptive study. Individual measures that explained substantial portions of the variability in ratings of knee joint-degenerative changes in patients with knee medial compartment osteoarthritis. SETTING: Outpatient orthopedic clinic and biomechanics and muscular assessment laboratory. PATIENTS: Volunteer sample of 20 subjects (age range, 59 +/- 9 yr) with no history of neurologic disease. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: We assessed degenerative changes, varus alignment, standing balance, and knee proprioception. Weight-bearing radiographs were used to assess the extent of degenerative changes and the degree of varus alignment. Single-limb standing balance control was assessed through tests performed on a force platform. Knee proprioception was assessed with an isokinetic dynamometer, using a joint angle replication test. RESULTS: Forward-stepwise multiple linear regression indicated that the extent of degenerative changes could be best predicted from a linear combination of the independent variables, varus alignment, and standing balance (R =.80, F(2,17) = 14.81, p =.0002). Sixty-four percent of the variability in ratings of degenerative changes was explained by alignment and standing balance measures (37% by varus alignment, 27% by standing balance). Alignment and balance measures were poorly correlated (r =.12, p =.63), further suggesting that they provided different information about gonarthrosis. CONCLUSIONS: Although varus alignment is widely accepted as a clinically important factor in gonarthrosis, and is the focus of many treatment efforts, our results suggest that objective measures of standing balance are also important. As a result, the potential impact of rehabilitation to improve the control of standing balance should be further evaluated in this patient population.

Biomechanical Phenomena↗

PubMed2001

Knee bracing for medial compartment osteoarthritis: effects on proprioception and postural control.

OBJECTIVE: To evaluate the effects of a functional knee brace specifically designed for patients with varus gonarthrosis on measures of proprioception and postural control. SUBJECTS: Fourteen men and six women (aged 59+/-9 yr) with measurable varus alignment and osteoarthritis of the knee medial compartment. METHODS: Proprioception was assessed in the sitting position using an isokinetic dynamometer and was quantified as the ability to replicate target knee-joint angles. Postural control was assessed with a force platform using tests of single-limb standing balance performed, while the patient was standing on a stable surface and standing on foam, and was quantified as the total length of the path of the centre of pressure. All tests were performed with and without the patient's own custom-fit valgus brace. RESULTS: Proprioception was significantly improved following application of the brace [mean difference=0.7 degrees, 95% confidence interval (CI)=0.2 to 1.1 degrees ). Postural control was not significantly affected by the use of the brace during the stable surface test (mean difference=2.6 cm, 95% CI=-4.3 to 9.5 cm) or the foam surface test (mean difference=0.9 cm, 95% CI=-7.5 to 9.4 cm). CONCLUSION: Although enhanced proprioception may be partially responsible for reported improvements with the use of a brace, the present findings call into question the functional importance of the small changes observed.

Braces↗

PubMed2001

Knee bracing after ACL reconstruction: effects on postural control and proprioception.

PURPOSE: To evaluate the effects an anterior cruciate ligament (ACL) brace has on various measures of knee proprioception and postural control. METHODS: Thirty subjects (mean age 27 +/- 11 yr) having undergone unilateral ACL reconstruction were tested with and without wearing their own custom-fit brace on their involved limb. Proprioception was assessed using joint angle replication tests completed on an isokinetic dynamometer. Postural control was assessed using a series of single-limb standing balance tests completed on a force platform. The balance tests included: 1) standing on the stable platform with eyes open, 2) standing on a foam mat placed over the platform with eyes open, 3) standing on the platform with eyes closed, and 4) standing on the platform after landing from a maximal single-limb forward hop. RESULTS: The brace provided a small but statistically significant improvement in proprioception (mean reduction in error scores between target and reproduced angles = 0.64 +/- 1.4 degrees, P = 0.02). For the postural control tests, there was a significant brace condition by test situation interaction (P = 0.02), with the brace providing a small but statistically significant improvement during the test completed on the stable platform with eyes open (mean reduction in center of pressure path length = 4.2 +/- 8.4 cm, P = 0.02) but not during the other more challenging test situations. Additional post hoc analyses indicated that the relationship between knee proprioception and postural control measures were low and not significant (r = 0.003 to 0.19, P > 0.32), consistent with the suggestion that changes in knee proprioception can occur in the absence of substantial changes in postural control. Also, standing balance tests that challenged the somatosensory contribution to postural control (i.e., those completed on foam, or with eyes closed) were significantly related to single-limb forward hop distances (r = -0.4, P < 0.05), whereas performance during the proprioception test was not (r = 0.1, P > 0.50). CONCLUSIONS: In general, bracing appears to improve performance during tasks characterized by relatively limited somatosensory input but not during tasks characterized by increased somatosenory input. The small magnitude of the improvements, coupled with their apparent lack of carry over to more difficult and functionally relevant tasks, questions the clinical benefit of the present effects of bracing.

Adult↗

PubMed2000

Effect of a neoprene sleeve on knee joint kinesthesis: influence of different testing procedures.

PURPOSE: Objectives of this study were to examine the perceived sense of knee joint position during selected test situations, and to evaluate the proposed kinesthetic effect of a neoprene knee sleeve during these test situations. METHODS: Fifty-nine young healthy subjects (39 females and 20 males) attempted to replicate target knee joint angles using active and passive knee extension movements completed in sitting (nonaxially loaded) situations, and during active knee extension movements completed in supine while applying a load of 15% body weight through the long axis of the tibia (axially loaded). The criterion measure used was the absolute difference between target and reproduced angles, averaged over five attempts (Average absolute difference: AAD). RESULTS: A three-way ANOVA (two genders by three test situations by two sleeve conditions), with repeated measures on the last two factors, indicated a significant main effect for test situation and sleeve condition (P < 0.05), but not for gender. There was also a significant test situation by sleeve condition interaction (P < 0.05). Post-hoc analysis indicated that the AAD score during the active nonaxially loaded test situation without the sleeve was significantly greater than AAD scores for all other tests (P < 0.01). CONCLUSIONS: Pre-existing differences in knee joint kinesthesis observed during different contexts of limb movement must be recognized before various interventions, including the effect of knee supports, can be adequately interpreted. Because knee joint position sense was attenuated during voluntary active movement, and because this attenuation was ameliorated by the use of a sleeve, future studies evaluating the kinesthetic effects of knee bracing may benefit from using active movements. However, since the sleeve did not affect performance during the axially loaded test situation, future studies should also evaluate the relationship between tests of knee joint kinesthesis and other more functional tests of neuromuscular performance.

Adult↗

PubMed2000

Intertester reliability of the McKenzie evaluation in assessing patients with mechanical low-back pain.

STUDY DESIGN: Prospective intertester reliability study investigating the ability of 2 therapists to agree on a low back pain diagnosis using examination techniques and the classification system described by McKenzie. OBJECTIVES: To investigate intertester agreement in determining McKenzie diagnostic syndromes, subsyndromes, presence, and relevance of the spinal deformities. BACKGROUND: Reliability of the McKenzie approach for determining diagnostic categories is unclear. Previous studies have been characterized by inconsistency of test protocols, criterion measures, and level of training of the examiners, which confounds the interpretation of results. METHODS: Patients were assessed simultaneously by 2 physical therapists trained in the McKenzie evaluation system. The therapists were randomly assigned as examiner and observer. Agreement was estimated by Kappa statistics. RESULTS: Forty-five subjects (47 +/- 14 years), composed of 25 women and 20 men with acute, subacute, or chronic low back pain were examined. The agreement between raters for selection of the McKenzie syndromes was kappa = 0.70, and for the derangement subsyndromes was kappa = 0.96. Interrater agreement for presence of lateral shift, relevance of lateral shift, relevance of lateral component, and deformity in sagittal plane was kappa = 0.52, 0.85, 0.95, and 1.00, respectively. Intertester agreement on syndrome categories in 17 patients under 55 years of age was excellent, with kapp = 1.00. CONCLUSIONS: A form of low back evaluation, using patterns of pain response to repeated end range spinal test movements, was highly reliable when performed by 2 properly trained physical therapists.

Adult↗

PubMed1998

Strength and pain measures associated with lateral epicondylitis bracing.

OBJECTIVE: To determine the effect of bracing on measures of pain-free grip strength and pain scores in individuals with unilateral lateral epicondylitis through a comparison of two elbow braces, a placebo brace, and a no-brace situation. DESIGN: Repeated-measures design in which the subjects acted as their own controls. SETTING: A clinical research laboratory at a hand and upper limb clinic. PATIENTS: Fifty individuals diagnosed by a physician with unilateral lateral epicondylitis, having symptoms for at least 3 weeks, were recruited from the community. INTERVENTIONS: The braces studied were the Count'R-Force Tennis Elbow Brace, the Body Glove Airprene Elbow Support, and a placebo brace that consisted of a modified DePuy Levy Clinic Patella Strap. MAIN OUTCOME MEASURES: Pain-free grip strength measured using an NK Biotechnical Corporation Hand Assessment System DIGIT-grip Device and pain scores measured on a visual numeric rating scale. RESULTS: No significant differences in pain-free grip strength or pain were observed between any of the test situations (p > .05). Pain during the test, however, was greater than pain before or after the test (p < .05). CONCLUSIONS: When tests were completed on one occasion with the brace on, no advantages of elbow bracing were detected. Whether bracing is effective when used as a treatment technique for an extended period of time should be addressed in future research.

Adult↗

PubMed1998

Measurement variability and sincerity of effort: clinical utility of isokinetic strength coefficient of variation scores.

Although the use of measures of strength variability as a means of judging sincerity of effort is becoming common practice, the accuracy of doing so has been questioned. Coefficient of variation (CV) cut-off points, indicating the upper limit of variability for repeated maximal efforts, are routinely used to identify workers providing submaximal efforts during various strength tests. However, the stability of the CV itself has not been considered when comparing an individual's observed CV score to these cut-off points. The purpose of the present study was to examine the day-to-day variability of the CV calculated from maximal isokinetic knee extension efforts, and to describe how this measurement error affects the accuracy of the CV as a distinguishing criterion between maximal and submaximal efforts. Thirty-one healthy males (mean age 25 +/- 4.5 years) completed three maximal and three submaximal isokinetic knee extension efforts on two separate occasions. Although submaximal CVs were significantly greater than maximal CVs (15.6 versus 3.7%; p < 0.01), there was considerable overlap between submaximal and maximal CV frequency distributions. More importantly, an individual observed CV could vary +/- 3.1% as a result of day-to-day variation or measurement error. This range in possible CV scores should be considered when comparing an individual's score to proposed cut-off points. Since individual CVs vary considerably from day-to-day, and since precise cut-off values distinguishing between maximal and submaximal conditions cannot be identified, CV scores must be interpreted cautiously, and the potential errors in relying extensively on this approach to identifying insincere efforts should be recognised.

Adult↗

PubMed1998

Identifying submaximal muscular effort: reliability of difference scores calculated from isometric and isokinetic measurements.

The present investigation examined the reliability of a derived strength measurement and also how variability between test sessions affects the utility of this variable for judging an individual's muscular effort. 31 young healthy men (M age = 25 yr.) completed three isometric and isokinetic concentric contractions of the knee extensors, using maximal and self-selected submaximal efforts, on each of two test sessions. Difference scores between isometric and isokinetic measurements were calculated by subtracting the mean of the three isokinetic peak torques from the mean of the three isometric peak torques for each individual subject for maximal and submaximal efforts performed on both test sessions. For the group of subjects, difference scores were significantly greater during maximal (33 +/- 29 Nm) than submaximal (13 +/- 30 Nm) efforts, suggesting subjects could not maintain the same relationship between isometric and isokinetic muscular actions across the maximal and submaximal conditions. However, the test-retest reliability of the difference scores was only modest even when data were averaged over two test sessions (intraclass correlation coefficients were .82 for maximal, and .58 for submaximal). As a result, the range of scores within which an individual's true score might be expected to lie was large (+/- 25 Nm for maximal, and +/- 37 Nm for submaximal). Although derived strength parameters like difference scores may be effective in distinguishing submaximal from maximal efforts completed by groups of subjects, the test-retest reliability of the present scores suggests that their use in judging an individual's performance may be limited.

Adult↗

PubMed1997

Cumulative trauma disorders in the upper extremities: reliability of the postural and repetitive risk-factors index.

OBJECTIVE: This study addresses test-retest reliability of the Postural and Repetitive Risk-Factors Index (PRRI) for work-related upper body injuries. This assessment was developed by the present authors. DESIGN: A repeated measures design was used to assess the test-retest reliability of a videotaped work-site assessment of subjects' movements. SUBJECTS: Ten heavy users of video display terminals (VDTs) from a local banking industry participated in the study. SETTING: The 10 subjects' movements were videotaped for 2 hours on each of 2 separate days, while working on-site at their VDTs. MAIN OUTCOME MEASURE: The videotaped assessment, which utilized known postural risk factors for developing musculoskeletal disorder, pain, and discomfort in heavy VDT users (ie, repetitiveness, awkward and static postures, and contraction time), was called the PRRI. The videotaped movement assessments were subsequently analyzed in 15-minute sessions (five sessions per 2-hour videotape, which produced a total of 10 sessions over the 2 testing days), and each session was chosen randomly from the videotape. The subjects' movements were given a postural risk score according to the criteria in the PRRI. Each subject was therefore tested a total of 10 times (ie, 10 sessions), over two days. The maximum PRRI score for both sides of the body was 216 points. RESULTS: Reliability coefficients (RCs) for the PRRI scores were calculated, and the reliability of any one session met the minimum criterion for excellent reliability, which was .75. A two-way analysis of variance (ANOVA) confirmed that there was no statistically significant difference between sessions (p < .05). Calculations using the standard error of measurement (SEM) indicated that an individual tested once, on one day and with a PRRI score of 25, required a change of at least 8 points in order to be confident that a true change in score had occurred. The significant results from the reliability tests indicated that the PRRI was a reliable measurement tool that could be used by occupational health practitioners on the job site.

Adult↗

PubMed1997

Eccentric peak torque of the plantar and dorsiflexors is maintained in older women.

Although a relative preservation of eccentric (ECC) strength with age has been reported previously, this phenomenon has not been studied in lower leg muscles. Concentric (CONC) and ECC plantar (PF) and dorsiflexion (DF) in healthy active older women (OW; n = 16, age = 67 +/- 4 years) and younger women (YW; n = 16, age = 27 +/- 4 years) were studied. Passive resistive torque of the plantar flexors and average rate of torque development (RTD) for both DF and PF were also measured. The OW had CONC peak torques that were 74% and 89% of the YW for PF and DF, whereas ECC peak torques were 97% and 100% of the YW. ECC torque patterns were almost identical for both groups, but there were significant differences for passive resistive torque (OW > YW; p < .01) and CONC RTD (OW < YW; p < .05). While increased passive resistive torque did not prove to be influential in maintaining ECC strength with age, it had a negative effect on CONC DF function.

Adult↗

PubMed1997

Functional knee braces and dynamic performance: a review.

OBJECTIVE: The purpose of the present review was to examine current experimental research on the effectiveness of functional knee braces (FKBs) used by patients with anterior cruciate ligament injury during dynamic performance tests. DATA SOURCES: Twelve studies published in peer-reviewed journals and listed in the Excerpta Medica system were reviewed. STUDY SELECTION: All studies compared braced and unbraced tests performed by the same subjects, using tests characterized by weight bearing/axial loading. DATA EXTRACTION: Studies were reviewed independently by three investigators. DATA SYNTHESIS: Tests included one-leg hop, figure-of-eight run, stair climbing, walking, cutting, agility runs, straight running, and bicycle ergometry. Experimental situations were classified as follows: (a) maximal effort tests, which compared overall measures of performance such as the distance hopped and the time to run a specific distance; and (b) matched submaximal effort tests, which compared specific variables such as electromyography, range of motion, ground reaction forces, and energy costs. Bracing was found to be advantageous in three of the 16 maximal effort situations, disadvantageous in two, and of no measurable effect in 11. Six of the 10 matched effort situations reported differences in the criterion measurements when braced, while four reported no differences. CONCLUSIONS: If FKB prescription is to be based solely on empirical evidence of efficacy from performance tests, then further investigation is required to provide this evidence. Future research needs to examine the subjective and psychological aspects of FKB usage along with the results of objective performance tests.

Braces↗

PubMed1997

Preferential activation of the vastus medialis oblique, vastus lateralis, and hip adductor muscles during isometric exercises in females.

Disagreement exists as to whether the individual components of the quadriceps femoris can be preferentially activated, i.e., that one muscle component is activated to a greater degree of its maximum voluntary contraction ability than the remaining components. Preferential activation of the vastus medialis (VM) might be useful in the treatment of knee patients demonstrating VM atrophy. The purpose of the present investigation was to determine if the vastus medialis oblique (VMO), vastus lateralis (VL), and hip adductor (HA) muscles were preferentially activated in females during the following maximal voluntary isometric exercises: 1) unilateral quadriceps setting (QS) with the ankle positioned in neutral, 2) unilateral quadriceps setting combined with ankle dorsiflexion (QS + D), and 3) maximal bilateral hip adduction. Integrated electromyography (IEMG in mV.sec) was determined for the VMO, VL, and HA muscles of the preferred leg (i.e., that used to kick a ball) of 20 healthy females. Data were normalized using QS exercise as the reference exercise. Nonnormalized IEMG (+/-SD) of the VMO and VL was similar during QS [i.e., VMO = 1050 (+/-802) mV.sec, VL = 1075 (+/-738) mV. sec] and QS + D exercises [i.e., VMO = 1191 (+/-738) mV.sec, VL = 1202 (+/-836) mV.sec], but significantly less than these values during hip adduction exercise [i.e., VMO = 174 (+/-62) mV. sec, VL = 194 (+/-70) mV.sec]. Nonnormalized IEMG of the HA muscles was similar during both QS and QS+D [i.e., 286 (+/-405) mV.sec and 195 (+/-432) mV.sec], but significantly higher than these values during hip adduction exercise [i.e., 413 (+/-235) mV.sec]. Normalized IEMG (+/-SD)(%) demonstrated similar patterns, i.e., the ratios for the VMO and the VL muscles did not differ from one another under either QS + D [i.e., VMO = 121 (+/-60)%, VL = 116 (+/-40)%] or hip adduction conditions [i.e., VMO = 33 (+/-24)%, VL = 36 (+/-25)%]. As a result, the degree of activation of the two muscles was considered the same. These results suggest no preferential activation of the quadriceps femoris component muscles during QS, QS + D, and hip adduction exercises in the nonweight-bearing position. The use of hip adduction to preferentially activate the VMO over the VL compared with QS exercises was not substantiated. A mean increase of 20% in the VMO and VL myoelectric activity during QS (as demonstrated by the normalized IEMG), by the addition of dorsiflexion, may be clinically significant. However, further study is required.

Adult↗

PubMed1997

Effectiveness of visual feedback during isokinetic exercise.

Although previous investigators have observed that knowledge of performance via visual feedback tends to enhance performance during an isokinetic test, the time frame over which visual feedback remains advantageous is unclear. The purpose of this study was to compare knee extensor torques produced by visual feedback and no visual feedback groups on three occasions, completed over a 2-week period, and at 4 weeks after the third test. Healthy, sedentary subjects were each randomly assigned to either a visual feedback or a no visual feedback group (N = 10 males and 10 females per group). Visual feedback consisted of viewing a computer monitor which displayed the current and a target knee extension force. Torques produced by the visual feedback group were consistently greater (p < 0.05) and more reliable than those produced by the no visual feedback group. The effectiveness of visual feedback tended to decrease over the first three occasions, suggesting that visual feedback may not be as advantageous once a skill is well learned. Further research needs to examine the contribution of visual feedback to motor learning as well as retention and transfer of motor skills during more complex functional tasks.

Adult↗

PubMed1996

A method of measuring standing isokinetic plantar and dorsiflexion peak torques.

Different methods have been used for concentric (CONC) isokinetic testing of ankle dorsiflexion (DF) and plantar flexion (PF). However, little information is available on either the reliability of these protocols or eccentric (ECC) torque production. As well, previous studies utilized non-weight-bearing test positions. The purpose of this study was to develop a reliable method of testing CONC and ECC DF and PF in a weight-bearing position. One group of adults, including older men and women were tested on two occasions with a standing protocol. Another group of older and younger men and women were compared between the standing method and a supine protocol. For both positions the velocity was 30 degrees.s-1 for the CONC and ECC actions, and the range of motion was 10 degrees DF to 20 degrees PF. Reliability coefficients for peak torque (PT) were acceptable and ranged from 0.65 to 0.90. The two testing positions were significantly related (r = 0.84-0.91), but CONC PT in standing were greater than supine. Therefore, this method of testing isokinetic DF and PF in a standing position has acceptable reliability and produces results consistent with those acquired with the supine protocol. It provides a means of comparing groups and examining intervention strategies while weight-bearing.

Aged↗

PubMed1996

Static and dynamic strength of the shoulder rotators in healthy, 45- to 75-year-old men and women.

Although clinicians routinely treat patients > 45 years of age and use ratio data in making treatment decisions, the reliability of performance of these individuals and the potential utility of ratio data are unclear. The purposes of the present study were to examine the reliability of peak torques and external/internal rotation (ER/IR) ratios for static, dynamic-concentric, and dynamic-eccentric tests and to determine the interrelationships between strength measurements in healthy 45- to 75-year-old subjects. Twenty men and 20 women (mean age = 59 +/- 9 years) were tested on two occasions, completed within 4-6 days. With subjects sitting and their dominant glenohumeral joint positioned in the scapular plane, two isolated contractions were completed at 0, 60, and 120 degrees/sec angular velocities. For peak torques (Nm), all 10 reliability coefficients > or = 0.83, whereas for external rotation/internal rotation (ER/IR) ratios (%), all five reliability coefficients < or = 0.67. Relative measurement error (standard error of measurement/ standard deviation) was much larger for ER/IR ratios (56-79%) than for peak torques (17-41%). Static and dynamic scores were highly related for peak torques (r = 0.72-0.89), but poorly related for ER/IR ratios (r = 0.23-0.36). The high variation associated with ratio data and its tendency not to follow the pattern of relationships which characterizes absolute data suggests that clinicians exercise caution when making treatment-related decisions using ratio data.

Aged↗

PubMed1995

Clinical applicability and test-retest reliability of an external perturbation test of balance in stroke subjects.

We address the test-retest reliability and clinical applicability of an adapted external perturbation balance assessment, ie, the Postural Stress Test (PST). Repeated-measures were designed to assess the clinical features of a component of balance disorder in stroke. Twenty ambulatory stroke patients and 20 age-, gender-, height-, and weight-matched healthy control subjects participated in this study. Stroke patients were tested (using the adapted PST) on 4 separate days; matched control subjects were tested on one occasion. With the subject standing, backward perturbation forces were applied at the level of the center of gravity. Postural reactions to the test were scored in real-time and from videotape, from two different viewing angles, ie, 45 degrees and 90 degrees to the saggital plane. Scores (out of a maximal of 81) were ascertained using a 10-point subjective-observational scale. None of the control subjects fell during testing; four of the hemiplegic subjects fell. Subjects were protected from potential injury by a custom-designed safety harness system. For the hemiplegic subjects, intraclass correlation coefficients (ICCs), calculated as the reliability of any one occasion, ranged from 0.71 to 0.77, whereas those calculated as the reliability of the mean of the first two occasions ranged from 0.83 to 0.93. Although scores on the fourth occasion were significantly greater than those on the third occasion, both being significantly greater than those on the first and second test occasions (p < .05), differences were less than 5 points on the 81-point scale.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1995

Effect of isokinetic strength-training on functional ability and walking efficiency in adolescents with cerebral palsy.

This study investigated changes in knee extensor and flexor strength of 17 mildly involved adolescents with cerebral palsy in response to an eight-week isokinetic strength-training program. Peak torque and work were used as strength outcome measures. Subsequent changes in gross motor function and walking efficiency were evaluated. The significant strength gains of 21 to 25 per cent observed were similar in magnitude to those previously reported for able-bodied individuals. A significant number of subjects showed an increase in gross motor ability. However, walking velocity and walking efficiency were unchanged. Strength gains of 15 to 17 per cent were maintained for three months after the cessation of isokinetic training.

Adolescent↗

PubMed1995

Concentric and eccentric knee extension strength in older and younger men and women.

Decrements in isometric and concentric (Conc) muscular strength with increased age are well documented. However, little information is available on the effects of aging on eccentric (Ecc) strength, even though Ecc or lengthening muscle actions are used in most physical activities. This study examined Conc and Ecc peak torques (PT) during knee extension at 90 degrees/sec in healthy older (62 to 89 yrs) and younger (20 to 29 yrs) men and women. Conc PT decreased more with age than did Ecc (p < 0.01), for both men and women. PT values for the older men and women as a percentage of those of the younger ones were 58.3 and 46.6% for Conc, and 75.1 and 61.7% for Ecc, respectively. These age differences need to be considered during isokinetic evaluations of Conc versus Ecc strength. Other muscle groups should be investigated, and mechanisms remain to be determined.

Adult↗