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At least 1,027 records · Page 57Linked to original sources
PubMed1999

Test-retest reliabilty of isokinetic hip adductor and flexor muscle strength.

OBJECTIVE: To determine the test-retest reliability of eccentric hip flexor and adductor peak torque and endurance using a Cybex Norm isokinetic dynamometer and to evaluate muscle soreness after exercise as a result of the testing procedure. DESIGN: Prospective test-retest reliability study. PARTICIPANTS: A total of 19 male volunteers (21-43 years old). INTERVENTION: Tests included hip flexor and adductor peak torque strength measured at 60 degrees/s (concentric and eccentric) and endurance measurements (total work done over 20 continuous concentric/eccentric contractions at 150 degrees/s). Subjects were tested on three occasions at 1-week intervals. MAIN OUTCOME MEASURES: Repeated measures analysis of variance was performed for all dependent variables including the subject's dominant and nondominant side among the three test sessions. Intraclass correlation coefficients (ICCs) were calculated to compare the data between sessions. In addition, simple linear regression analysis was completed to determine the relationship between session measurements for all measures with ICC > 0.75. RESULTS: The main findings of this study are that eccentric peak hip adductor torque was reliably measured on a Cybex Norm isokinetic dynamometer using a continuous eccentric/ concentric cycle protocol at a speed of 60 degrees/s (ICC > 0.84). Peak concentric adductor torque and peak eccentric and concentric hip flexor torque were less reliable using the same protocol (ICC < 0.67). Endurance measurements, using total work done over 20 repetitions, were not reliable for hip flexor and adductor muscle groups using a continuous eccentric/concentric cycle protocol at a speed of 150 degrees/s (ICC < 0.55). Posttest muscle soreness was found to be of significant concern with such a protocol. CONCLUSION: The results from this test-retest reliability study confirm the reliability of eccentric peak hip adductor torque measurements for use clinically and in future research. In addition, the need to assess posttest muscle soreness after isokinetic muscle testing is confirmed.

Adult↗
PubMed1982

Rehabilitation of knee flexor and knee extensor muscle strength in patients with meniscectomies, ligamentous repairs, and chondromalacia.

The purpose of this investigation was to determine the relationship of torque developed by knee extensor muscles to torque developed by knee flexor muscles as a result of rehabilitation programs for patients with chondromalacia, ligamentous repairs, and meniscectomies. Peak torque of knee extensor and flexor muscles was measured at slow dynamic and rapid dynamic tension on the involved and homologous noninvolved limb. The rehabilitation program produced significant changes in the torque of the involved limb at both dynamic tensions for each group of patients. The knee extensor muscles of the involved limb were not rehabilitated to the level of the knee extensor muscles of the noninvolved limb were rehabilitated to the level of those of the noninvolved limb. The ratio of flexor to extensor muscle torque seemed dependent on the nature of the injury and the rate of displacement. The ratio of flexor to extensor muscle torque of the involved limb was not rehabilitated to that of the homologous noninvolved limb. In rehabilitating muscles of the knee, attention must be directed to the ration between the flexor and extensor muscle torque of the knee.

Adolescent↗
PubMedDate not supplied

Hamstring injuries in sprinters. The role of concentric and eccentric hamstring muscle strength and flexibility.

Eleven sprinters with recent hamstring injuries were compared with nine uninjured runners. The flexibility of the hamstrings and the eccentric and concentric muscle torque were measured in the hamstrings and quadriceps muscles at different angular velocities. Sprinters with a previous hamstring injury had significantly tighter hamstrings than uninjured sprinters had. The uninjured sprinters had significantly higher eccentric hamstring torques at all angular velocities. They also had significantly higher concentric quadriceps and hamstring torques at 30 deg/sec but not at higher velocities. Sprinters with a history of hamstring injury thus differed from uninjured runners, being weaker in eccentric contractions and in concentric contractions at low velocities.

Adolescent↗
PubMed2005

Intrarater reliability of 1 repetition maximum estimation in determining shoulder internal rotation muscle strength performance.

The purpose of this study was to determine intrarater reliability of the 1 repetition maximum (1RM) estimation for shoulder internal rotation. The accuracy of the estimated 1RM was determined by establishing the actual 1RM. Fifteen subjects were positioned supine with the shoulder in 0 degrees abduction (position 1) and prone with the shoulder in 90 degrees abduction (position 2). Subjects were placed in both testing positions and performed resisted shoulder internal rotation. A 1RM estimation equation was used to estimate shoulder internal rotation strength. After 1 week, procedures were repeated and intrarater reliability was calculated. One week after 1RM estimation procedures were completed, the accuracy of an estimated 1RM was determined by establishing an actual 1RM. The results indicated excellent intrarater reliability for position 1 (intraclass correlation coefficient [ICC] = 0.99) and position 2 (ICC = 0.96). The correlation coefficients for accuracy indicated excellent concurrent validation was attained for position 1 (ICC = 0.99) and position 2 (ICC = 0.97). Shoulder internal rotation 1RM estimation appears to be reliable and accurate. Clinicians may use submaximal loads to estimate the 1RM and decrease the possibility of injury during actual 1RM strength testing.

Adult↗
PubMed2003

Interrelationships between muscle structure, muscle strength, and running economy.

PURPOSE: The present study was designed to investigate possible differences in running economy (RE) among elite middle-distance runners by examining muscle structure and maximal isometric force (MVC). METHODS: Ten young male runners ran at six different running speeds. During the running bouts, respiratory gases, and blood lactate were measured. Muscle biopsies were obtained from the vastus lateralis muscle for analyzing fiber type distribution, muscle fiber area, myosin heavy chain (MHC) composition, activities of a number of metabolic enzymes (citrate synthase, lactate dehydrogenase, phosphofruktokinase, and 3-hydroxyacyl-CoA-dehydrogenase), and titin isoforms. RESULTS: Energy expenditure (EE) increased linearly up to the speed of 6.0 m.s. The relative distribution of the MHC isoforms was MHC I: 67.0%, MHC IIA: 31.5%, and MHC IIX: 1.5%. The present results demonstrated that higher the area of Type II fibers, higher the MVC (r = 0.59, P< 0.05). The amount of MHC II correlated inversely with EE when running close to the competition speed (r = -0.61, P< 0.05). Enzyme activities did not correlate significantly with either RE or EE. Titin analysis revealed that a faster-mobility titin band was observed in all subjects, whereas a lower-mobility titin band was observed only in the most economical runner. CONCLUSION: Differences in RE among homogeneous group of middle-distance runners were observed at various running speeds. This may partly be explained by differences in muscle fiber distribution, MHC composition, and titin isoforms.

Adult↗
PubMed1998

Association of IgM type anti-GM1 antibodies and muscle strength in chronic acquired demyelinating polyneuropathy.

The pathogenetic role of anti-GM1 in chronic acquired demyelinating polyneuropathy (CADP) is uncertain. An association between antibodies and disease activity has not yet been established. In 8 patients with CADP followed longitudinally, anti-GM1 antibodies were monitored with a standardized enzyme-linked immunosorbent assay technique and muscle performance with isokinetic dynamometry. During a mean observation period of 24 months, strength improved in 6 of 8 patients by a median value of 54.5%, and anti-GM1 fell in all 6 patients; the reduction being 43%. In 2 patients, muscle performance deteriorated by 30 and 8%, whereas anti-GM1 titers increased by 10 and 9%, respectively. The relative change in anti-GM1 was inversely related to muscle performance. Clinical scoring of muscle performance according to the Medical Research Council scale failed to show an association with anti-GM1. It is concluded that anti-GM1 antibodies are closely related to disease activity, and that the close association indicates a role of anti-GM1 in the pathogenesis of CADP.

Adult↗
PubMed1996

Neck flexor muscle strength, efficiency, and relaxation times in normal subjects and subjects with unilateral neck pain and headache.

OBJECTIVE: To determine the test-retest reliability of a new method for measuring muscular strength, efficiency, and relaxation times of the neck flexor musculature of healthy adults, and to compare these neck flexor muscle properties in subjects who have unilateral neck pain and headache with those in controls. DESIGN: Subjects lay supine and isometrically flexed their necks against a force transducer attached to the back of a webbing and velcro helmet. Electromyograms (EMGs) were recorded from surface electrodes on the sternocleidomastoid (SCM) muscles. Two consecutive sessions of five contractions of varying levels of effort from minimal through moderate and maximal effort were analyzed. SETTING: Ambulatory referral center. PARTICIPANTS: Volunteer control subjects (n = 10, 3 men and 7 women) were recruited from hospital and university personnel. Volunteer neck pain subjects (n = 10, 3 men and 7 women) were recruited from a physiatric chronic pain practice and a hospital outpatient physical therapy practice. RESULTS: In the controls, the intraclass correlation coefficients (ICCs) for the first two maximum neck flexion contractions were; peak force ICC = .81; peak force/body weight ICC = .75; average force ICC = .75; force relaxation time ICC = .73; SCM EMG relaxation times: right ICC = .60 and left ICC = .67. Comparing sessions 1 and 2 the intraclass correlations for SCM efficiencies were right ICC = .58 and left ICC = .97. The peak force in controls (mean = 45.3 +/- 17.6N) was reduced by 50% in the neck pain subjects (mean = 22.4 +/- 13.1N) (p = .004). Similarly, peak force/body weight in the neck pain subjects (X = 0.3 +/- 0.2N/kg) was 46% of control (mean = 0.7 +/- 0.2N/kg) (p = .001), and average force in the neck pain subjects (X = 12.1 +/- 7.5N) was 43% of controls (mean = 28.5 +/- 11.0N) (p = .001). In two neck pain subjects. SCM, EMG and force relaxation times were abnormally long in both the affected and the unaffected SCM muscles, exceeding the control values by greater than 3 standard deviations. The difference between the right SCM efficiency of the control subjects (mean = 0.3 +/- 0.2N/ microV) and the affected SCM efficiency of the neck pain subjects (mean = 0.1 +/- 0.1 N/microV) approached the p < .05 criterion for significance (p = .055). CONCLUSION: The technique was found to be highly reliable for the measurement of neck flexor peak force, peak force/body weight, average force, and force relaxation time, and moderately reliable for the quantitation of SCM EMG relaxation times and SCM efficiency. All force values were significantly lower in the neck pain population compared with the controls. In the neck pain population, force and SCM EMG relaxation times, as well as efficiencies, suggested abnormalities. Neck pain subjects showed no significant differences in SCM EMG relaxation time or SCM efficiency between affected and unaffected SCM muscles.

Adult↗
PubMed2002

Effects of heavy resistance/power training on maximal strength, muscle morphology, and hormonal response patterns in 60-75-year-old men and women.

Eleven women (TRW; 64 +/- 4 yrs) and ten men (TRM; 65 +/- 5 yrs) participated in the strength/power training twice a week for 24 weeks. Basal concentrations of serum total and free testosterone, growth hormone (GH), dehydroepiandrosterone sulfate (DHEAS), cortisol and sex hormone binding globulin (SHBG) as well as acute responses of serum total and free testosterone, growth hormone (GH) were measured. Maximal 1RM strength in the squat, chair rise time and muscle fibre distribution and areas of type I and IIa and IIb of the vastus lateralis were also examined. 1RM squat increased in TRW by 26 (SD10)% (p < .001), and in TRM by 35 (7)% (p < .001) and chair rise time improved in both groups (p < .001). Fibre areas increased in type I, (p < .01), IIa (p < .01) and IIb (p < .01) in TRM and type I (p < .05) and IIa (p < .05) in TRW. The proportion of type IIa increased from 31% to 43% (p < .05) in TRW and that of type IIb decreased from 27% to 17% (p < .05) in TRW and from 25% to 17% (p < .05) in TRM. Individual concentrations of testosterone/cortisol ratios correlated (r = 0.63; p < .05) with the individual increases in 1RM strength in TRW. The exercise sessions resulted in acute increases in serum GH in both groups (p < .05) with a further increase (p < .01) up to 10 minutes post-loading in TRM at post-training.

Aged↗