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Results for “Muscle Strength Dynamometer”

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PubMed2005

Effects of long-term tennis playing on the muscle-bone relationship in the dominant and nondominant forearms.

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 +/- 5.8 yrs, 16.2 +/- 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p < 0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81-0.84, p < 0.0001). The correlations were still significant after adjusting for whole-body BMC, body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone.

Absorptiometry, Photon↗

PubMed2002

The "spray can" sign: validation of a clinical observation in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND: The presentation of chronic inflammatory neuropathies is variable. The decision regarding when to intervene with treatment is ideally determined by identifying early markers of loss of function. OBJECTIVE: To test the hypothesis that an observation of functional impairment, defined by a patient with demyelinating neuropathy, can be used as a reproducible and reliable measure of improvement with intravenous immune globulin. DESIGN: A 28-year-old woman presented with a chronic inflammatory demyelinating polyneuropathy. Her first complaint was the inability to use her deodorant spray because of hand weakness. A calibrated pincer gauge fixed on top of her usual spray can was used to objectively test finger flexion. Tip grip and lateral pinch were also measured. A calibrated dynamometer was used to measure grip strength. RESULTS: Power and precision grip force were reproducible in normal control subjects by means of the spray can test. This test proved to be a reliable indicator of reduced muscle strength in the patient and improved after treatment with intravenous immune globulin. CONCLUSIONS: The spray can test objectively quantified the daily function, nominated by the patient, of operating an aerosol can. This measurement, drawn from a functional loss observed by the patient, proved to be a portable and reliable indicator of decline and recovery in chronic inflammatory demyelinating polyneuropathy.

Adult↗

PubMedDate not supplied

Reliability and validity of the BTE-Primus grip tool.

This study was designed to examine the reliability and validity of the newly designed grip tool of the Baltimore Therapeutic Equipment (BTE)-Primus and to investigate the effects of body position (sit versus stand), handedness, and fatigue on grip strength. The subjects performed maximal grip strength tests using the Jamar dynamometer and the BTE-Primus. Intraclass correlation coefficients were calculated for test-retest reliability and criterion-related validity. A repeated measures analysis of covariance was conducted to reveal differences in grip strength between instruments, body positions, hands, and sessions. The BTE-Primus grip tool was found to be reliable (r = 0.97 to 0.98) and valid (r = 0.95 to 0.96). There were no significant differences in grip strength scores between the Jamar and the BTE-Primus or between sitting and standing. Grip strength scores of the right hand were significantly greater than those of the left hand, and grip strength scores in the first session were significantly greater than those in the second session. The results of this study indicate that clinicians can use the BTE-Primus grip attachment at the second handle setting and know that is reliable, valid, and comparable to the second-handle setting of the Jamar dynamometer.

Adolescent↗

PubMed1993

Reliability of isokinetic muscle strength testing in 45- to 78-year-old men and women.

The test-retest reliability of isokinetic muscle strength testing was determined in 45- to 78-year-old men (N = 71; mean age = 60.2 years) and women (N = 107; mean age = 60.0 years). The dynamic muscle strength of the knee and elbow extensor (KE, EE) and flexor (KF, EF) muscle groups was measured at slow (60 degrees/sec) and fast (K = 240 degrees/sec; E = 180 degrees/sec) angular velocities using a Cybex II isokinetic dynamometer on two occasions seven to ten days apart. The mean peak torque in the second test was significantly higher (p < 0.001) in all muscle groups and both angular velocities tested in both sexes. The angle at which peak torque occurred did not change from the first to the second test except in the KF of females tested at 60 degrees/sec. Pearson's correlation coefficients (CCs; p < 0.01) in males ranged from .68 to .77 in the knee and from .71 to .84 in the elbow. In females, the CCs (p < 0.01) ranged from .58 to .74 in the knee and from .67 to .78 in the elbow. Thus in a large number of older men and women at least two tests may be necessary to determine isokinetic peak torque.

Adult↗

PubMed1988

Strength conditioning in older men: skeletal muscle hypertrophy and improved function.

The effects of strength conditioning on skeletal muscle function and mass were determined in older men. Twelve healthy untrained volunteers (age range 60-72 yr) participated in a 12-wk strength training program (8 repetitions/set; 3 sets/day; 3 days/wk) at 80% of the one repetition maximum (1 RM) for extensors and flexors of both knee joints. They were evaluated before the program and after 6 and 12 wk of training. Weekly measurements of 1 RM showed a progressive increase in strength in extensors and flexors. By 12 wk extensor and flexor strength had increased 107.4 (P less than 0.0001) and 226.7% (P less than 0.0001), respectively. Isokinetic peak torque of extensors and flexors measured on a Cybex II dynamometer increased 10.0 and 18.5% (P less than 0.05) at 60 degrees/s and 16.7 and 14.7% (P less than 0.05) at 240 degrees/s. The torque-velocity relationship showed an upward displacement of the curve at the end of training, mainly in the slow-velocity high-torque region. Midthigh composition from computerized tomographic scans showed an increase (P less than 0.01) in total thigh area (4.8%), total muscle area (11.4%), and quadriceps area (9.3%). Biopsies of the vastus lateralis muscle revealed similar increases (P less than 0.001) in type I fiber area (33.5%) and type II fiber area (27.6%). Daily excretion of urinary 3-methyl-L-histidine increased with training (P less than 0.05) by an average 40.8%. Strength gains in older men were associated with significant muscle hypertrophy and an increase in myofibrillar protein turnover.

Aged↗

PubMed2000

Effect of salbutamol on muscle strength and endurance performance in nonasthmatic men.

PURPOSE: The ergogenic effect of acute beta2-adrenergic agonist administration in nonasthmatic individuals has not been clearly demonstrated. Therefore, the acute effects of oral administration of the beta2-adrenergic agonist salbutamol (4 mg) on muscle strength and endurance performance were studied in 16 nonasthmatic men in a double-blind randomized cross-over study. METHODS: Peak expiratory flow (Mini Wright Peakflowmeter), isokinetic strength of the knee extensors and knee flexors at four angular velocities (Cybex II dynamometer), and endurance performance in a cycle ergometer test until exhaustion at 70% of maximal workload were measured. RESULTS: Peak expiratory flow increased from 601 +/- 67 L x min(-1) to 629 +/- 64 L x min(-1) after salbutamol (P < 0.05). Peak torque was higher after salbutamol than after placebo (4.4% for the knee extensors, 4.9% for the knee flexors) (P < 0.05). Mean endurance time increased from 3,039 +/- 1,031 s after placebo to 3,439 +/- 1,287 s after salbutamol (P = 0.19). When four subjects complaining about adverse side effects were excluded from the analysis, the increase in endurance time (729 +/- 1,007 s or 29%) was statistically significant (P <-0.05). Salbutamol did not affect VO2, respiratory exchange ratio, heart rate, and plasma free fatty acid and glycerol concentration during exercise; plasma lactate and potassium concentrations were increased (P < 0.05). CONCLUSIONS: Under the conditions of this study, oral salbutamol appears to be an effective ergogenic aid in nonasthmatic individuals not experiencing adverse side effects.

Administration, Oral↗

PubMed2001

Postural control and torque of the knee joint after healed tibial shaft fracture.

Muscular atrophy occurs as a consequence of trauma and immobilisation. This cohort comparison study was conducted to evaluate the limb function after healed tibial shaft fractures, which were treated by casting versus nailing. Balance (as centre of pressure) and muscle strength (as torque of the knee joint during knee extension) have been measured in 27 patients with tibial shaft fractures with a mean age of 39 (19-73) years, 1 year after fracture healing. Fourteen patients were treated by intramedullary nailing 'nailed group' and 13 by plaster cast with or without minimal internal fixation 'casted group'. Centre of pressure was measured on a force platform. Knee extension torque was measured during isometric and concentric muscle actions by an isokinetic dynamometer. Centre of pressure tended to be more towards the uninjured leg in patients who had been treated by plaster cast (P<0.05). Side-to-side differences for isometric torque were significantly higher within the casted group (P<0.05). Patients with tibial shaft fractures treated by intramedullary nailing showed better postural control, one-leg standing test, and side-to-side differences for isometric muscle strength compared with patients treated by cast. Therefore, we recommend intramedullary nailing as a better method of treatment for tibial shaft fractures, with regard to recovery of muscle function.

Adult↗

PubMed1999

Lean mass and physical activity as predictors of bone mineral density in 16-20-year old women.

OBJECTIVE: The aim of the study was to quantify the inter-relationship between bone mineral density and physical activity, muscle strength, and body mass composition in a group of healthy 16-20-year-old women. DESIGN: A cross-sectional study. SETTING: Reykjavik area. SUBJECTS: Two-hundred and fifty-four Icelandic Caucasian women aged 16, 18 and 20 years, randomly selected from the registry of Reykjavik. MAIN OUTCOME MEASURES: Bone mineral content (BMC) and density (BMD) in lumbar spine, hip, distal forearm and total skeleton and lean mass and fat mass were measured with dual energy X-ray absorptiometry (DEXA) and compared with grip strength measured with a dynamometer and physical activity as assessed by a questionnaire. RESULTS: The lean mass had the strongest correlation with BMC and BMD, stronger than weight, height and fat mass, both in univariate analysis (r = 0.41-0.77; P<0.001) and in linear regression analysis. The total skeletal BMD was logarithmically higher by hours of exercise per week (P<0.001)). About 30% of variability in total skeletal BMD in this age group can be predicted by lean mass and physical exercise. CONCLUSIONS: Modifiable factors, such as exercise and adequate muscle seem to be significant predictors of the attainment of peak bone mass in women.

Absorptiometry, Photon↗

PubMed1991

Rehabilitation and biomechanics.

In the area of rehabilitation and biomechanics, several articles divided into five categories, including therapeutic heat, foot and ankle orthotics, exercise in elderly arthritis patients, muscle strengthening in rheumatoid arthritis, and arthroplasty and immobilization are reviewed. Superficial heat was demonstrated to increase intra-articular temperature, and therefore, may be detrimental. On the other hand, local deep microwave hyperthermia appears to have potential therapeutic benefits. The role and effectiveness of foot orthotic devices are reviewed. The problem and treatment of forefoot varus is emphasized. A new technique of measuring subpedal pressure in the shoe is presented, demonstrating reduced foot pressures by certain types of footwear. Rheumatoid arthritis and osteoarthritis wee present in 23% of a nursing home population, but were a substantial factor for placement in only 15%. However, this group had higher pain scores, depended more on wheelchair use, and was more likely to have significant functional limitations. Exciting new data on strengthening the quadriceps in the frail elderly, whose mean age was 90.2 years, are reviewed. The relationship of quadriceps muscle strength and maximum voluntary strength as a function of age and gender and the effects of an endurance training program in 15 physically compromised nursing home residents is discussed. A static and a dynamic training program for rheumatoid arthritis patients were compared. The dynamic group significantly increased muscle strength, endurance, and aerobic capacity as compared to the static group, without any increase in disease activity. The results further showed that a home program was beneficial. Interesting data presented show that using a Cybex isokinetic dynamometer (Lumex, Bayshore, NY) test was reliable for normal control and for rheumatoid arthritis patients who were stronger.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗

PubMed1999

Muscle performance in detoxified alcoholics.

OBJECTIVE: Although numerous reports have described alcohol muscle dysfunction (myopathy) in histochemical and morphological terms, a description of the relative impact of alcoholism on the functional capabilities (strength, power) of the various muscle groups of the arms and legs has not been reported. METHOD: The strength of flexor and extensor muscles of the elbow, knee and ankle was evaluated in a group of healthy detoxified white, alcoholic men (N = 83) and lifestyle control subjects (N = 61) using a computer-operated isokinetic dynamometer. RESULTS: The muscle mass (muscle-plus-bone cross-sectional area) did not differ significantly in alcoholics and controls for any of the limbs studied. Tests of isokinetic torque, work and power revealed small deficits (3-8%) in alcoholics in muscle groups involved in elbow flexion/extension, knee extension and ankle dorsiflexion. Tests of isometric torque in the knee extensors at different degrees of muscle stretch revealed approximately 4-6% lower torque in alcoholics at four different muscle lengths. The force-velocity (isoinertia knee extension) measures indicated slightly slower speeds of contraction (3.9-6.6%) in alcoholics under varying load conditions. CONCLUSIONS: The small magnitude of the muscle performance deficit in this group of alcoholics was less than expected and is probably related to (1) the elimination of subjects with other medical comorbidities or polydrug abuse, (2) the comparison with a control group of somewhat similar lifestyle and (3) the long (35-day) detoxification period elapsing before testing.

Adult↗

PubMed1997

Muscle strength and soft tissue composition as measured by dual energy x-ray absorptiometry in women aged 18-87 years.

Dual energy x-ray absorptiometry (DEXA) offers the possibility of assessing regional soft tissue composition, i.e. lean mass (LM) and fat mass: LM may be considered a measure of muscle mass. We examined age-related differences in LM, percentage fat (%fat) and muscle strength in 100 healthy non-athletic women aged 18-87 years. Relationships between muscle strength and leg LM in 20 elite female weight lifters and in 18 inactive women with previous hip fractures were also studied. The LM and %fat of the whole body, trunk, arms and legs were derived from a whole body DEXA scan. Isokinetic knee extensor strength (KES) and flexor strength (KFS) at 30 degrees.s-1 were assessed using an isokinetic dynamometer. The women aged 71-87 years had 35% lower KES and KFS than the women aged 18-40 years (P < 0.0001). Differences in LM were less pronounced. The LM of the legs, for instance, was 15% lower in the old than in the young women (P < 0.0001). In a multiple regression analysis with age, body mass, height and leg LM or KES as independent variables and KES or leg LM as the dependent variable, age was the most important predictor of KES (r(partial) = -0.74, P < 0.0001). The same applied to KFS. Body mass, not age, was the most important predictor of leg LM (r(partial) = 0.65, P < 0.0001) and of LM at all other measurement sites. The LM measured at different regions decreased equally with increasing age. The KES:leg LM ratio was negatively correlated with age (r = -0.70, P < 0.0001). The weight lifters had significantly higher KES:leg LM ratios than age-matched controls (+ 12%, P < 0.0001) and vice versa for the women with previous hip fractures (-36%, P < 0.0001). In conclusion, from our study it would seem that in healthy nonathletic women, age is a more important determinant of muscle strength than is LM as measured by DEXA. Muscle strengthening exercises and inactivity seem to have a considerably stronger influence on muscle strength than on LM.

Absorptiometry, Photon↗

PubMed2005

Relation between foot arch index and ankle strength in elite gymnasts: a preliminary study.

BACKGROUND: Gymnasts usually start intensive training from early childhood. The impact of such strenuous training on the musculoskeletal system is not clear. OBJECTIVES: To evaluate the relation between muscle strength of the ankle joint and foot structure in gymnasts. METHODS: The study population comprised 20 high level male gymnasts and 17 non-athletic healthy male controls. Arch indices were measured using a podoscope. Ankle plantar/dorsiflexion and eversion/inversion strengths were measured using a Biodex 3 dynamometer within the protocol of concentric/concentric five repetitions at 30 degrees /s velocity. RESULTS: The mean arch index of the right and left foot of the gymnasts and the controls were respectively: 31.4 (29.1), 34.01 (34.65); 60.01 (30.3), 63.75 (32.27). Both the arch indices and the ankle dorsiflexion strengths were lower in the gymnasts. Although no correlation was found between strength and arch index in the control group, a significant correlation was observed between eversion strengths and arch indices of the gymnasts (r = 0.41, p = 0.02). CONCLUSIONS: Whether or not the findings indicate sport specific adaptation or less training of the ankle dorsiflexors, prospective data are required to elucidate the tendency for pes cavus in gymnasts, for whom stabilisation of the foot is a priority.

Adaptation, Physiological↗

PubMed2004

Concentric quadriceps and hamstrings isokinetic strength in volleyball and soccer players.

AIM: Muscular strength is one of the most important components of sport, both for high performance and for injury prevention. One of the most used methods to assess strength muscle balance between dominant (D)/non-dominant (ND) and antagonist/agonist is isokinetic testing. The main purpose of the present study was to describe and to compare isokinetic strength profiles (peak torque, bilateral strength differences between D/ND leg (BD) and hamstrings/quadriceps (H/Q) ratio) in athletes of different sports and positional roles. METHODS: Twenty-eight elite volleyball players and 47 pro soccer players (goalkeepers, n = 5; full-backs, n = 7; defenders, n = 10; midfielders, n = 15; forwards, n = 10) were evaluated using an isokinetic dynamometer (Biodex-System 2). Maximal gravity corrected concentric peak torque of knee extensor and flexor muscles were measured at angular velocities of 360 degrees x s(-1) (6.28 rad x s(-1)) and 90 degrees x s(-1) (1.57 rad x s(-1)). RESULTS: No significant BD were found between soccer and volleyball players with exception of hamstrings at 90 degrees x s(-1) (soccer: 10.6 +/- 8.0% vs volleyball: 6.9 +/- 5.5%). The H/Q ratio was significantly lower in volleyball players at 90 degrees x s(-1) (D: soccer 57.4 +/- 6.7% vs volleyball 50.4 +/- 7.2%; ND: soccer: 56.1 +/- 8.2% vs volleyball: 50.5 +/- 6.4%). No significant differences were found for BD and H/Q ratio in soccer players of different positional roles. CONCLUSION: In general, soccer and volleyball players do not seem to be different concerning BD although a significant difference was observed in hamstrings at 90 degrees x s(-1). Moreover, our data suggest that specific demands of these sports and the different positional roles in soccer did not induce bilateral leg imbalances. However, sport demands seem to influence isokinetic concentric H/Q ratio.

Adult↗

PubMed1998

Concentric versus enhanced eccentric hamstring strength training: clinical implications.

OBJECTIVE: Hamstring injuries can be quite debilitating and often result in chronic problems. Eccentric muscle actions are often the last line of defense against muscle injury and ligament disruption. Traditionally, the focus of hamstring strength rehabilitation has been on concentric muscle actions. The purpose of our study was to compare hamstring muscle strength gains in concentric and eccentric hamstring strength training. DESIGN AND SETTING: A randomized-group design was used to examine differences in 1-repetition maximum (1 RM) and isokinetic strength values among 3 groups of subjects. Subjects were tested in a biomechanics laboratory using an isokinetic dynamometer, while training was carried out in a physical therapy outpatient clinic. SUBJECTS: Twenty-seven healthy male subjects (age = 22.9 +/- 3.1 years, wt = 81.8 +/- 12.9 kg, ht = 178.6 +/- 7.2 cm) participated in this study. Subjects were randomly assigned to 1 of 3 treatment groups: eccentric training, concentric training, or control. MEASUREMENTS: Subjects performed hamstring curls using an isotonic weight training device. Pretest 1 RM weight values were determined for all subjects using a standardized 1 RM protocol. In addition, maximum concentric and eccentric isokinetic strength values for knee-flexion strength were determined. Control group subjects refrained from weight training for 6 weeks. Subjects in the training groups trained 2 days per week for 6 weeks (12 sessions). After 6 weeks of training, all subjects returned for 1RM and isokinetic posttesting. RESULTS: The concentric group improved 19%, while the eccentric group improved 29%. The control group subjects did not show any significant change over the 6 weeks. In addition, there were improvements in eccentric isokinetic peak torque/ body weight ratios at both 60 degrees s and 180 degrees from pretesting to posttesting in the eccentric training group only. CONCLUSIONS: Our results demonstrate the effectiveness of isotonic strength training on the development of hamstring muscle strength. More important is the dramatic effect of eccentric strength training on overall hamstring muscle strength, both isotonic and isokinetic. Clinicians should consider using eccentric hamstring strengthening as part of their rehabilitation protocols for hamstring and knee injuries.

Journal Article↗

PubMed1998

Fatigue during repeated eccentric-concentric and pure concentric muscle actions of the plantar flexors.

OBJECTIVE: To compare the fatigue development during pure concentric actions with eccentric-concentric actions in standardized isokinetic, open-chain conditions. DESIGN: The study was performed with measurement of muscular strength and EMG of the plantar flexors on an isokinetic dynamometer. BACKGROUND: Fatigue development on a dynamometer has mostly been studied with repeated pure concentric actions. Eccentric-concentric actions are, however, often used in normal activities. An eccentric action has an immediate effect on a following concentric action and therefore it is of interest to follow the fatigue process in repeated combined actions. METHODS: Ten healthy young women participated. The pure concentric test was performed with the same number of cycles as in the eccentric-concentric test, which was performed until exhaustion. Development of MPF and RMS of the EMG in the triceps surae, as well as work, were evaluated. RESULTS: The total amount of work was significantly higher in the eccentric-concentric test than in the pure concentric test. The work decreased similarly (32-39%) with no significant difference between the two tests. A significant decrease (12-16%) in MPF was only seen in the eccentric-concentric test. No changes in RMS were seen. CONCLUSION: The similar reductions of work seen in both tests should primarily be sought in the contractile process as such. Changes in MPF may then be viewed as a phenomenon dependent on the timing of the duty cycle. RELEVANCE: The eccentric-concentric test lead to exhaustion and showed EMG changes and should therefore be recommended when evaluating the development of fatigue in muscular performances in different groups of patients.

Journal Article↗

PubMedDate not supplied

Recovery of sensory and motor function after nerve repair. A rationale for evaluation.

In order to identify an effective test for evaluating the results of nerve repair, 25 patients, age 10-53 years (mean 27 years), were evaluated two to five years after median or ulnar nerve repair at the distal forearm level. The initial assumption was that evaluation after nerve repair should reflect four aspects of recovery: reinnervation, tactile gnosis, integrated sensory and motor functions, and pain or discomfort. The evaluation included a number of assessment methods addressing these aspects. Attention was paid to the usefulness of the tests with reference to their relevance for assessing hand functions. Clinical utility and possibilities for standardization and quantification of the results were considered important. Statistical analysis showed no correlations between the results obtained in clinical tests for reinnervation and the results from neurophysiologic examination. Grip strength and cold intolerance together accounted for a significant 51% of the variance in activities of daily living (ADL) capacity. Tactile gnosis correlated weakly with ADL capacity and strongly with age. Based on these findings, the following design for evaluating the result after median and ulnar nerve repair is suggested. To assess reinnervation: Semmes-Weinstein monofilaments and manual muscle-testing; to assess tactile gnosis: classic 2PD and a test with the features of the used shape identification test; to assess integrated functions: selected parts of Sollerman's grip test and grip-strength test with Jamar dynamometer; to quantify pain and discomfort: a four-ranked scale for grading perceived problems from cold intolerance and hypersensitivity.

Activities of Daily Living↗

PubMedDate not supplied

Reconstruction of skin and tendon defects from wound complications after Achilles tendon rupture.

Four patients who developed combined tendon and overlying skin defects following operative repair of ruptured Achilles tendon were presented. Three patients had an infected wound. The average interval from the first operation for repairing the ruptured Achilles tendon and the reconstructive procedure was 46.2 days (range, 5-65 days). All patients were treated with a one-stage operation including radical debridement, reconstruction of the Achilles tendon defects using vascularized or nonvascularized tendon grafts, transfer of peroneus brevis for augmentation, and skin coverage with a free flap. The patients recovered uneventfully. The average follow-up period was 39.2 months (range, 18-79 months). In all patients, an evaluation of the clinical outcome, the performance of the calf muscles using a computerized dynamometer, and structural changes of the reconstructed Achilles tendon using magnetic resonance (MR) imaging were made. The clinical outcome was excellent in three patients and good in one. In isokinetic testing (Cybex-Norm), strength was found to be normal in one patient and abnormal in three patients. MR images revealed an intratendinous area of homogenous and normal intensity signal, and a significant increase in thickness and width in all levels of the reconstructed Achilles tendon. The authors conclude that it is possible to obtain satisfactory function in patients with complex wounds in the region of the Achilles tendon.

Achilles Tendon↗

PubMed1984

Size and strength of the quadriceps muscles of old and young women.

Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n = 25) and in their 20s (n = 25) and have compared it with the mid-thigh cross-sectional area of the same muscles. The two groups of women showed similar variability when strength was measured on consecutive days (coefficients of variation: 8%). The older women were 35% weaker than the young women (P less than 0.001) and their quadriceps cross-sectional area was 33% less (P less than 0.001). Quadriceps strength and cross-sectional area were correlated (r = 0.66, P less than 0.001, elderly; r = 0.53, P less than 0.01, young) and the principal axis of the relationship was closely similar for the two groups of women. There is therefore no difference in the intrinsic strength of the quadriceps muscles of healthy women in their third and eighth decades. This report also provides normative data for the objective evaluation of quadriceps weakness and/or wasting in female patients. The techniques involved are straightforward, the dynamometer is easily made, and compound ultrasound imaging is widely available.

Adult↗