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PubMed2005

Evaluation of female pelvic-floor muscle function and strength.

Evaluation of pelvic-floor muscle (PFM) function and strength is necessary (1) to be able to teach and give feedback regarding a woman's ability to contract the PFM and (2) to document changes in PFM function and strength throughout intervention. The aims of this article are to give an overview of methods to assess PFM function and strength and to discuss the responsiveness, reliability, and validity of data obtained with the methods available for clinical practice and research today. Palpation, visual observation, electromyography, ultrasound, and magnetic resonance imaging (MRI) measure different aspects of PFM function. Vaginal palpation is standard when assessing the ability to contract the PFM. However, ultrasound and MRI seem to be more objective measurements of the lifting aspect of the PFM. Dynamometers can measure force directly and may yield more valid measurements of PFM strength than pressure transducers. Further research is needed to establish reliability and validity scores for imaging techniques. Imaging techniques may become important clinical tools in future physical therapist practice and research to measure both pathophysiology and impairment of PFM dysfunction.

Electromyography↗
PubMed2004

Handgrip strength, pulmonary function tests, and pulmonary muscle strength in fibromyalgia syndrome: is there any relationship?

OBJECTIVE: It has been reported that patients with fibromyalgia syndrome (FMS) have lower maximal respiratory pressures than healthy subjects, indicating reduced pulmonary muscle strength. It has also been reported that patients with FMS have reduced grip strength. In this study, we aimed to examine the possible relationship between handgrip strength as a determinant of peripheral muscle strength and pulmonary muscle strength in patients with FMS by comparing them with healthy controls. METHODS: Forty-one consecutive women with FMS (diagnosed according to the American College of Rheumatology 1990 criteria) were compared with 40 age- and body mass index-matched healthy female controls. Pulmonary function tests were assessed by spirometry. Maximal pulmonary pressures were evaluated using an oral pressure meter. A dyspnea score was obtained. Pain was scored according to visual analogue scale and chest pain was classified (0-9) in fibromyalgia patients. Chest expansion was also measured in the two groups. Tender points were also evaluated in FMS patients. Grip strength (Jamar handheld dynamometer) was also measured in the two groups. RESULTS: The difference in pulmonary function tests was not statistically significant between groups. Maximal respiratory pressures (maximum inspiratory pressure and maximum expiratory pressure) and endurance (maximum ventilatory volume) were significantly lower in patients with FMS than in controls. There was also a statistically significant difference between groups regarding grip strength. There was also significant correlation between maximal inspiratory pressure and maximal expiratory pressure values and handgrip strength in patients with FMS. CONCLUSION: These data indicate that handgrip strength may be a determinant of pulmonary muscle strength in fibromyalgia patients.

Adult↗
PubMed2005

Cervical muscles weakness in chronic whiplash patients.

BACKGROUND: Isometric cervical strength has been used for assessing the severity of cervical spine pathologies. However there is a conspicuous dearth of information relating to cervical strength data in patients suffering from chronic whiplash. Therefore the objective of this study was to compare absolute and ratio-based isometric cervical strength scores in chronic whiplash patients with reported corresponding scores in healthy subjects. METHODS: Isometric cervical strength was measured in the directions of flexion, extension, right and left lateral flexion in 97 patients, 51 women and 46 men, using a wall-mounted dynamometer. FINDINGS: Compared to published values of normal subjects, whiplash patients suffered sharp reductions of about 90% in both genders and in all directions. The consistency of the isometric cervical strength scores as indicated by the mean coefficient of variation was relatively low, 17% and 20% in men and women respectively. The flexion/extension strength ratio ranged 0.8--0.9, slightly higher than the reported range for normal subjects. This ratio was highly correlated (r=0.91, P=0.01) with the mean coefficient of variation in a subgroup of 9 patients. INTERPRETATION: In the absence of an obvious reason such as sever atrophy or grossly dysfunctional neurological control the indicated weakness of the cervical muscles may be associated with learned pain avoidance behavior which is typical among this group of patients.

Adult↗
PubMed2001

Identifying feigned isokinetic trunk extension effort in normal subjects: an efficiency study of the DEC.

STUDY DESIGN: A test-retest comparison of maximal and feigned trunk extension effort in normal subjects was performed. OBJECTIVE: To test the robustness of an index termed DEC for differentiating maximal from feigned effort in normal subjects. SUMMARY OF BACKGROUND DATA: Previous studies have indicated that the DEC, which is the difference between the eccentric to concentric strength ratio at two test velocities, is a powerful identifier of feigned effort. This has been found for various muscle groups including the trunk extensors. However, whether this efficiency is affected by exposure to the protocol, learning, or other factors had not been examined. METHODS: Using a KinCom isokinetic dynamometer, 18 men and 17 women were tested twice within 1 to 2 weeks. Concentric and eccentric efforts of the trunk extensors were exerted using a short range of motion (20 degrees ) and two test velocities (10 degrees and 40 degrees per second). In the first part of each test, participants exerted maximal force against the lever arm, whereas in the second part they were to feign their maximal capability, pretending the presence of injury. RESULTS: In both Tests I and II, the feigned DEC scores (DECf) of all the participants were greater than the maximal DEC (DECm) scores (P = 0.0001). Repeated measurement analysis showed that neither DECm nor DECf varied systematically from Test 1 to Test 2. On the basis of the individual male scores, the DEC cutoff score of 0.41 was 100% efficient in Test 1 at differentiating feigned from maximal effort, with neither false-positive nor false-negative cases. Test 2 had a single false-positive case (efficiency 95%), and the optimal cutoff score was 0.275. In the female group, the corresponding efficiency of the DEC was 82% (optimal cutoff, 0.35) for Test 1 and 70% (optimal cutoff, 0.25-0.35) for Test 2. A statistical model for tolerance intervals at 90%, 95% and 99% indicated higher cutoff values for women than men. CONCLUSION: In healthy subjects, the DEC effectively differentiates feigned from maximal performance.

Adult↗
PubMed1994

Pain inhibition of shoulder strength in patients with impingement syndrome.

Fourteen patients with Stage II or III impingement syndrome (average age 58 years) were studied. Nine patients had full-thickness rotator cuff tears documented by arthrograms. Patients initially underwent a thorough shoulder examination followed by baseline isokinetic strength testing. Abduction/adduction testing was performed utilizing a Biodex dynamometer. Maximum concentric contractions were performed, and values for peak torque (PT), total work (W), and power (P) were obtained. All patients received a subacromial injection of 5 cc 1% lidocaine plus 5 cc 0.5% bupivacaine (Marcaine). After 5 minutes the testing sequence was repeated. Clinically, patients demonstrated marked improvement following injection. Eighty-six percent reported complete pain relief; the remaining two patients reported only mild discomfort at the extremes of motion. Improvement in functional activity of the affected shoulder was noted by all subjects. On manual muscle testing, 13 of 14 patients (93%) demonstrated increased abduction strength; 11 of 14 (79%) had improvement in external rotation. Mean increases in active forward elevation and external rotation were 36 degrees and 11 degrees, respectively (P < .01). Postinjection isokinetic changes in PT, W, and P for abduction/adduction were dramatic. For abduction, all patients showed significant increases in P (mean 82%), W (mean 90%), and PT (mean 48%) (all P < .05). No significant differences in range of motion testing or strength parameters were noted based on the presence or absence of a rotator cuff tear. For adduction, all patients showed significant increases in P (mean 208%), W (mean 183%), and PT (mean 41%) (all P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Relation between open and closed kinematic chain assessment of knee strength and functional performance.

OBJECTIVE: To assess the relationship between concentric isokinetic quadriceps and hamstring strength values with the single leg hop for distance test, a closed kinematic chain activity. DESIGN: Correlational study. SETTING: Neuromuscular Research Laboratory, University of Pittsburgh. PARTICIPANTS: Subjects for this study consisted of 37 college-aged volunteers (21 men, 16 women: mean age = 22.76 +/- 3.52 years, height = 169.90 +/- 10.60 cm, weight = 69.31 +/- 14.60 kg) with no previous history of injury to the lower extremity. INTERVENTION: Each subject performed three trials of a single leg hop for distance test for the dominant and nondominant limbs followed by isokinetic evaluation. Isokinetic strength was assessed with the Biodex System II Isokinetic Dynamometer (Biodex Medical Inc., Shirley, NY, U.S.A.) for the quadriceps and hamstrings at preset angular velocities of 60 degrees/s (5 repetitions) and 180 degrees/s (30 repetitions). Before testing, each subject completed a dynamic warm-up period that consisted of submaximal cycling at a fixed cadence of 60 revolutions/min followed subsequently by quadriceps and hamstring muscle stretching. MAIN OUTCOME MEASURES: The distance hopped in centimeters was converted to a ratio of the distance hopped to the individual leg length measured from the anterior superior iliac spine to the medial malleolus. Isokinetic values were obtained for peak torque (Nm), peak torque/body weight (%), total work (Nm), and average power (W). MAIN RESULTS: Low to moderate significant relationships were found to exist between the single leg hop for distance test and the isokinetic variables for the quadriceps and hamstrings of both limbs at each test velocity. Significant correlation coefficients ranged from r = 0.33 to r = 0.69 at 60 degrees/s and r = 0.33 and r = 0.67 at 180 degrees/s. Correlation coefficients were found to be statistically greater for the hamstrings than the quadriceps for total work and average power at 60 degrees/s and for peak torque/body weight, total work, and average power at 180 degrees/s (p < 0.05). CONCLUSIONS: Concentric quadriceps and hamstring strength seem to demonstrate a significant contribution to the single leg nop for distance test; however, the hamstring muscles may play a more important role during the propulsive phase, thereby enabling subjects to jump further.

Adult↗
PubMed1999

Eversion strength analysis of uninjured and functionally unstable ankles.

OBJECTIVE: Functional ankle instability (FAI) afflicts many athletes. Several causes of FAI have been implicated, including peroneal muscle weakness. Traditional musculoskeletal rehabilitation programs have focused on concentric muscle strength. The purpose of our study was to compare concentric and eccentric isokinetic and isometric eversion ankle strength measurements between subjects identified as having unilateral FAI and subjects having no history of inversion ankle sprain. DESIGN AND SETTING: Employing a matched-pairs technique, subjects with no history of ankle injury were compared with subjects with unilateral FAI using isokinetic and isometric measures of eversion ankle strength. Strength testing was performed in a sports medicine clinic setting. SUBJECTS: Forty-two subjects volunteered for this study: 21 subjects suffered from unilateral FAI (age = 19.3 +/- 1.1 years, wt = 84.0 +/- 9.5 kg, ht = 181.5 +/- 9.2 cm), while 21 subjects served as matched-paired controls (age = 19.5 +/- 1.2 years, wt = 82.5 +/- 10.9 kg, ht = 179.5 +/- 7.9 cm). MEASUREMENTS: Ankle eversion concentric and eccentric strength (peak torque) was assessed at 0 degrees /s, 30 degrees /s, 60 degrees /s, 90 degrees /s, 120 degrees /s, 150 degrees /s, and 180 degrees /s using an isokinetic dynamometer. RESULTS: We found no significant differences in concentric, eccentric, or isometric eversion ankle strength between the 2 groups of subjects. CONCLUSIONS: The exact cause of FAI remains elusive. Based on our results, those who suffer from unilateral FAI do not appear to have eversion strength deficits. Unless clear evidence of weakness exists, clinicians may find that eversion strength training exercises are unnecessary. Future research should examine other causes of FAI, including reciprocal muscle group strength ratios and proprioception deficits.

Journal Article↗
PubMed2005

Limb muscle dysfunction in COPD: effects of muscle wasting and exercise training.

PURPOSE: Lower-limb muscle weakness has often been reported in COPD, and contributes to exercise intolerance. Controversial information is available regarding upper-limb muscle adaptations and the influence of muscle wasting on muscle weakness. We investigated leg and arm muscle function in 59 stable COPD patients (GOLD stage III) with preserved fat-free mass (FFM) and in 28 patients with reduced FFM relative to age- and sex-matched healthy control subjects and studied the effects of 8 wk of whole-body exercise training. METHODS: FFM was measured with bioelectrical impedance analysis. Isokinetic quadriceps (F-leg) and biceps strength (F-arm), as well as quadriceps (E-leg) and biceps endurance (E-arm) were determined with a Biodex dynamometer. Exercise training consisted of cycle ergometry, treadmill walking, weight training, and gymnastics during 5 d.wk. RESULTS: F-leg (76.2 +/- 3.6 vs 118.2 +/- 6.3 N.m, P < 0.001) and F-arm (25.6 +/- 1.3 vs 38.1 +/- 2.1 N.m, P < 0.001) were significantly and similarly reduced in the COPD patient group compared with controls. Also, E-leg (-2.13 +/- 0.12 vs -1.61 +/- 0.11, P < 0.01), but not E-arm (-2.72 +/- 0.11 and -2.47 +/- 0.13 NS), was decreased in patients. F-leg (62.4 +/- 4.3 vs 82.8 +/- 4.7 N.m, P < 0.01), but not F-arm or muscle endurance, was reduced in FFM-depleted compared with non-FFM-depleted patients. Whereas after training F-leg and E-leg significantly increased by 20% in the whole COPD group, biceps muscle function remained unchanged. CONCLUSION: Lower- and upper-limb muscle dysfunction was observed in COPD patients, irrespective of the presence of FFM depletion. Generalized muscle weakness suggests systemic muscular involvement, although the preserved arm endurance and the poor response of arm performance to exercise training is indicative for intrinsic differences in muscular adaptations between leg and arm muscles.

Case-Control Studies↗
PubMed1997

Comparison between estimates of hand volume and hand strengths with sex and age with and without anthropometric data in healthy working people.

Edema and hand strength measurements are useful for the recovery assessment of patients with a hand lesion. This work determined and compared estimates of hand volume, grip strengths (measured with a Jamar and a Collins dynamometer), and pinch strength (with a Jamar pinch gauge) in terms of sex and age with or without anthropometric indices in healthy working people. The sample included 100 subjects from within the staffs of two rehabilitation centres. For both grip strengths, multiple linear regression models including body height, weight, and arm muscle area were very good (multiple correlation coefficient R of about 0.84) and clearly better than those obtained with sex and age only. For pinch strength, the best estimate was obtained with sex and arm muscle area (R of 0.76); for hand volume, the model with sex, body height, and weight provided the best result (R of 0.93). These findings suggested that anthropometric indices easy to measure must be taken into account to estimate hand volume and hand strengths.

Adult↗
PubMed1987

The relationship of knee and ankle weakness to falls in nursing home residents: an isokinetic study.

The strength of the knees and ankles of a group of nursing home residents with a history of falls was compared to age-matched controls. Peak torque (PT) and power (POW) were recorded at two limb velocities (60 degrees/s and 120 degrees/s) on a Cybex II Isokinetic dynamometer for four muscle groups: knee extensors, knee flexors, ankle plantar flexors and ankle dorsiflexors. The PT and POW of fallers were significantly decreased for all four muscle groups in comparison to controls, with the ankles showing the greatest decrements. Although POW in fallers was significantly lower at the higher velocity in both joints, the decrease was most prominent in the ankles. Dorsiflexion POW production in fallers was the most affected of all the motions (7.5 times less than the control value). At the higher, more functional limb velocities, ankle weakness particularly involving the dorsiflexors appears to be an important factor underlying poor balance.

Accidental Falls↗
PubMed1996

Various treatment techniques on signs and symptoms of delayed onset muscle soreness.

Eccentric activities are an important component of physical conditioning and everyday activities. Delayed onset muscle soreness (DOMS) can result from strenuous eccentric tasks and can be a limiting factor in motor performance for several days after exercise. An efficacious method of treatment for DOMS would enhance athletic performance and hasten the return to activities of daily living. The purpose of this study was to identify a treatment method which could assist in the recovery of DOMS. In the selection of treatment methods, emphasis was directed toward treatments that could be rendered independently by an individual, therefore making the treatment valuable to an athletic trainer in team setting. DOMS was induced in 70 untrained volunteers via 15 sets of 15 eccentric contractions of the forearm extensor muscles on a Lido isokinetic dynamometer. All subjects performed a pilot exercise bout for a minimum of 9 weeks before data collection to assure that DOMS would be produced. Data were collected on 15 dependent variables: active and passive wrist flexion and extension, forearm girth, limb volume, visual analogue pain scale, muscle soreness index, isometric strength, concentric and eccentric wrist total work, concentric and eccentric angle of peak torque. Data were collected on six occasions: pre- and post-induced DOMS, 20 minutes after treatment, and 24, 48, and 72 hours after treatment. Subjects were randomly assigned to 1 of 7 groups (6 treatment and 1 control). Treatments included a nonsteroidal anti-inflammatory drug, high velocity concentric muscle contractions on an upper extremity ergometer, ice massage, 10-minute static stretching, topical Amica montana ointment, and sublingual A. montana pellets. A 7 x 6 ANOVA with repeated measures on time was performed on the delta values of each of the 15 dependent variables. Significant main effects (p < .05) were found for all of the dependent variables on time only. There were no significant differences between treatments. Therefore, we conclude that none of the treatments were effective in abating the signs and symptoms of DOMS. In fact, the NSAID and A. montana treatments appeared to impede recovery of muscle function.

Journal Article↗
PubMedDate not supplied

Muscle strength of trunk flexion-extension in post-stroke hemiplegic patients.

This study was undertaken to determine muscle strength of trunk flexion-extension in hemiplegic patients after stroke compared with that of normal controls. The design consisted of a nonrandomized control trial in a secondary care setting (a rehabilitation unit at a hospital facility). The subjects included 25 post-stroke male hemiplegic patients and 25 male healthy controls. The maximal peak torques of trunk flexion-extension at angular velocities of 0 degrees (isometric contraction), 60 degrees, 120 degrees, and 150 degrees/s were measured by using an isokinetic dynamometer (Cybex Trunk Extension-Flexion Unit, Cybex, Ronkonkoma, NY). Peak torque of trunk flexion and extension in hemiplegic patients was significantly smaller than that of healthy controls (P < 0.05), except isometric trunk flexion (P > 0.05). The weakness of trunk flexion-extension muscles in hemiplegic patients might be accounted for by the bilateral innervation from the motor cortex, the insufficient use of high threshold motor units, and disuse atrophy.

Abdominal Muscles↗
PubMed2004

Structured exercise improves calf muscle pump function in chronic venous insufficiency: a randomized trial.

OBJECTIVE: Deterioration of calf muscle pump function is associated with progression of chronic venous insufficiency (CVI). We postulated that a supervised exercise program would improve calf muscle strength and venous hemodynamics in patients with CVI. METHODS: We recruited 31 patients for this randomized, prospective trial. Inclusion criteria required the presence of skin changes or ulceration (CEAP 4, 5, 6), and duplex ultrasound scanning (reflux or scarring) and air plethysmographic (APG) evidence of CVI. Subjects were randomized into control (n = 13) and therapy (n = 18) groups. Class II (30-40 mm Hg) compression hosiery was given to all. The experimental group received physical therapy designed specifically to strengthen calf musculature. Dynamic strength and power were measured with a Biodex II dynamometer (Biodex Medical Systems, Shirley, NY) at slow and fast speeds. Reflux (venous filling index) and calf pump function (ejection fraction, residual volume fraction) were measured with APG. Quality-of-life questionnaires and venous severity scores were also administered. Outcomes were compared 6 months after initiation of exercise. Probability of treatment effect was tested with univariate analysis of variance, with control for baseline values. RESULTS: Demographic variables and medical comorbidities were not different between groups. After 6 months of intervention, indicators of calf pump function returned to a normal range in the therapy (experimental) group. Mean residual volume fraction was improved in the exercise group (-8.75 +/- 4.6 vs 3.4 +/- 2.9 in the control group; P <.029). Mean ejection fraction was increased in the exercise group (3.48 +/- 2.7 vs -1.4 +/- 2.1 in the control group; P <.026). Reflux, while substantially greater than the normal value of 2.0 mL/s in both groups, was unchanged. The exercise regimen improved isokinetic peak torque/body weight at both slow speed (3.1 +/- 1.4 in the therapy group vs -1.0 +/- 1.1 in the control group; P <.05) and fast speed (2.8 +/- 0.9 in the therapy group vs - 0.3 +/- 0.6 in the control group; P <.03). No changes were observed in quality-of-life or severity scores. CONCLUSIONS: Calf muscle pump function and dynamic calf muscle strength were improved after a 6-month program of structured exercise. Directed physical conditioning of the calf musculature may prove beneficial for patients with or without alternative management options for severe CVI. Further research on exercise for patients with CVI is warranted.

Aged↗
PubMed2004

A 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players.

PURPOSE: To compare the effects of a 10-week training program with two different exercises -- traditional hamstring curl (HC) and Nordic hamstrings (NH), a partner exercise focusing the eccentric phase -- on muscle strength among male soccer players. METHODS: Subjects were 21 well-trained players who were randomized to NH training (n = 11) or HC training (n = 10). The programs were similar, with a gradual increase in the number of repetitions from two sets of six reps to three sets of eight to 12 reps over 4 weeks, and then increasing load during the final 6 weeks of training. Strength was measured as maximal torque on a Cybex dynamometer before and after the training period. RESULTS: In the NH group, there was an 11% increase in eccentric hamstring torque measured at 60 degrees s(-1), as well as a 7% increase in isometric hamstring strength at 90 degrees, 60 degrees and 30 degrees of knee flexion. Since there was no effect on concentric quadriceps strength, there was a significant increase in the hamstrings:quadriceps ratio from 0.89 +/- 0.12 to 0.98 +/- 0.17 (11%) in the NH group. No changes were observed in the HC group. CONCLUSION: NH training for 10 weeks more effectively develops maximal eccentric hamstring strength in well-trained soccer players than a comparable program based on traditional HC.

Adult↗
PubMed2004

Are unilateral and bilateral patellar tendinopathy distinguished by differences in anthropometry, body composition, or muscle strength in elite female basketball players?

BACKGROUND: Overuse injury to the patellar tendon (patellar tendinopathy) is a major reason for interrupted training and competition for elite athletes. In both sexes, the prevalence of unilateral and bilateral tendinopathy has been shown to differ. It has been proposed that bilateral pathology may have a different aetiology from unilateral pathology. Investigation of risk factors that may be unique to unilateral and bilateral patellar tendinopathy in female athletes may reveal insights into the aetiology of this condition. OBJECTIVES: To examine whether anthropometry, body composition, or muscle strength distinguished elite female basketball players with unilateral or bilateral patellar tendinopathy. METHODS: Body composition, anthropometry, and muscle strength were compared in elite female basketball players with unilateral (n = 8), bilateral (n = 7), or no (n = 24) patellar tendinopathy. Body composition was analysed using a dual energy x ray absorptiometer. Anthropometric measures were assessed using standard techniques. Knee extensor strength was measured at 180 degrees /s using an isokinetic dynamometer. z scores were calculated for the unilateral and bilateral groups (using the no tendinopathy group as controls). z scores were tested against zero. RESULTS: The tibia length to stature ratio was approximately 1.3 (1.3) SDs above zero in both the affected and non-affected legs in the unilateral group (p<0.05). The waist to hip ratio was 0.66 (0.78) SD above zero in the unilateral group (p<0.05). In the unilateral group, leg lean to total lean ratio was 0.42 (0.55) SD above zero (p<0.07), the trunk lean to total lean ratio was 0.63 (0.68) SD below zero (p<0.05), and leg fat relative to total fat was 0.47 (0.65) SD below zero (p<0.09). In the unilateral group, the leg with pathology was 0.78 (1.03) SD weaker during eccentric contractions (p<0.07). CONCLUSIONS: Unilateral patellar tendinopathy has identifiable risk factors whereas bilateral patellar tendinopathy may not. This suggests that the aetiology of these conditions may be different. However, interpretation must respect the limitation of small subject numbers.

Adolescent↗
PubMed1989

Effect of thyroid dysfunction on thigh muscle efficiency.

To establish whether muscle weakness in thyroid dysfunction can be attributed solely to muscle atrophy (i.e. reduction in the total muscle cross-section) or whether the intrinsic contractile strength of the muscle is reduced per unit cross-sectional area, the ratio between thigh muscle strength and thigh muscle area was determined before and after treatment of hyper- and hypothyroidism. Midthigh muscle areas, assessed by computer tomography, increased in all seven hyperthyroid and decreased in three of four hypothyroid patients investigated after treatment of the thyroid disease. Peak torque and total work output, assessed by an isokinetic dynamometer (Cybex II), increased in both groups of patients. The muscle efficiency (total work output per cm2 muscle) increased in all patients after therapy [mean +/- SD values before vs. after therapy in hyperthyroid patients, 17.6 +/- 5.3 vs. 30.5 +/- 3.7 joules (J)/cm2 (P less than 0.001); in hypothyroid patients, 12.8 +/- 6.1 J/cm2 vs. 25.8 +/- 8.6 J/cm2 (P less than 0.05)]. Thus, the present study demonstrates that patients with thyroid dysfunction have altered muscle mass and diminished muscle efficiency.

Adult↗
PubMedDate not supplied

Electromyographic analysis of effort in grip strength assessment.

The purpose of the present research was to investigate the use of surface EMG in assessing effort while measuring grip strength with the Jamar dynamometer. We hypothesized that sincere, maximal grip contractions could be distinguished from feigned, submaximal contractions by differences in the amplitude and frequency content of the EMG, as well as by differences in force. Healthy subjects (seven men and ten women) were instructed on different trials to give a sincere (maximal, 100%) effort or a feigned (50% of maximal) effort with the right hand. The subjects were tested at each of the five handle positions of the Jamar dynamometer. Surface EMG was obtained for the right palmaris longus/flexor carpi radialis muscles. Consistent with previous research, we found that the 50% efforts, compared to 100% efforts, showed, (1) lower peak force; (2) a slower rise to peak force; and (3) a different pattern of force measurements as a function of handle position. Feigned and sincere efforts also differed in the EMG. As hypothesized, amplitude was lower for 50% than 100% efforts. The frequency spectra of the EMG were obtained by Fourier analysis. The 50% efforts showed a higher frequency EMG than did the 100%. The results supported the hypothesis that surface EMG may provide a measure of effort in a grip strength task. Analysis of the EMG, in conjunction with force analysis, has the potential of being a valuable tool for the clinician needing to determine whether a patient is giving a sincere, maximal effort or is feigning.

Adult↗
PubMed1995

Isokinetic eccentric exercise.

The development of active isokinetic dynamometers has allowed the assessment of muscular moment under eccentric activations that have different characteristics to concentric actions. It is well documented that at a given angular velocity the eccentric moment is greater than the corresponding concentric moment. The moment-velocity relationship under eccentric conditions has been investigated, with conflicting results. Particularly, eccentric moment was reported to remain similar to, or to increase or decrease with, increasing angular velocity. As with concentric actions, the reliability of isokinetic eccentric measurements is influenced by a number of factors such as gravity, preload force and testing position. The velocity-specific effects of eccentric training have not been extensively investigated. Based on current knowledge, eccentric exercise does not appear to be velocity-specific. Although the mode specificity of both concentric and eccentric exercises have been investigated, the resultant observations are conflicting. Eccentric training has been found to improve both concentric and eccentric strength: yet, it has also been reported to improve only concentric or eccentric strength. The reciprocal muscle group ratios under eccentric actions were found not to be influenced by angular velocity, but the significant role of the eccentric/concentric moment ratio of each muscle has not been examined thoroughly. It is well documented that eccentric activations are associated with delayed muscle soreness and muscle damage. A limited number of studies have reported that isokinetic eccentric efforts may result in a lower amount of muscle soreness compared with other exercise modalities. Isokinetic dynamometers provide some unique characteristics for rehabilitation applications. Examination of the clinical application of eccentric exercise is limited. Consequently, the use of this exercise modality in prevention and assessment of musculoskeletal injuries should be investigated further.

Athletic Injuries↗