Relationship between grip strength and global muscle strength in community-dwelling older people

There are still conflicting results regarding the association between grip and global muscle strength in older people. Therefore, the objective of the present study was to determine the association between grip strength and global muscle strength, as well as between grip strength and individual trunk, hip, knee and ankle muscle strengths.MethodsGrip strength was assessed using a manual dynamometer, and trunk, hip, knee and ankle muscle strength with an isokinetic dynamometer, in order to obtain the global muscle strength variable, in 150 older men and women from the community. The association between grip and global muscle strength and between grip strength and the strength of each muscle group was determined through the Pearson correlation test, followed by multivariate linear regression adjusted for sex, age, body mass index, level of physical activity and number of comorbidities.ResultsA positive significant association was found between grip strength and global muscle strength in older people (r = 0.690; β = 10.07; p < 0.001; R² = 0.604), even after adjustment. There was also a low to moderate association between all the muscle groups and grip strength. However, when the model was adjusted, the relationship between grip strength and ankle dorsiflexor peak torque lost significance (p = 0.924).ConclusionGrip strength can represent global muscle strength in younger older people in the community, even when confounding variables are considered in the statistical model. However, grip strength does not eliminate the need for specific assessment of different muscle groups, when indicated.     

Relationships between muscle strength and bone mineral density of three body regions in sedentary postmenopausal women

This cross-sectional study was designed to investigate correlations between muscle strength and regional bone mineral density (BMD) in sedentary postmenopausal women. Sixty-two women who ranged in age from 41 to 76 years were investigated. Hip and trunk muscle strength was measured by isokinetic dynamometry. Grip strength of the nondominant hand was measured using a hand-held dynamometer. Bone mineral density of the lumbar spine, femur, and distal radius was measured by dual-energy X-ray absorptiometry. Only the correlation between hip abductor strength and femoral BMD was significant (P=0.009, r=0.327). There was no correlation between trunk muscle strength and lumbar vertebral BMD or between grip strength and distal radius BMD. Subjects with osteoporosis (T score <–2.5) or osteopenia T (–2.5 to –1) and normal subjects (T>–1) exhibited similar isokinetic hip and trunk muscle strength. Women with osteoporotic distal radii had significantly lower grip strength than subjects who were osteopenic or normal at this site, but the osteoporotic group was also significantly older. In conclusion, our results indicate that the isokinetic strength of hip abductors weakly correlates with femoral BMD in postmenopausal women with and without osteoporosis. Trunk muscle strength did not correlate with lumbar vertebral BMD in either of these groups. The weaker handgrip we observed in the women with osteoporotic radii may be attributed to older age.     

Biodex等速系统测试老年人膝关节屈伸肌力可靠性的初步研究

目的确定Biodex等速系统测试老年人膝关节伸肌和屈肌等速向心肌肉功能的可靠性。方法使用Biodex System 3型多关节等速系统在2个测试日对20名老年人（年龄71±6岁）的双下肢进行等速向心肌力测试。结果除了屈肌的作功疲劳度值,伸肌和屈肌两次测试的峰力矩、单次最大作功和平均功率值差异均有统计学意义（P〉0．05）。伸肌和屈肌两次重复测试的相关系数在0．40～0．96之间,除屈肌的作功疲劳度值的P值〉O．05,其余各指标的P值均〈0．05,具有相关关系。结论采用Biodex等速系统对老年人膝关节伸肌和屈肌进行的肌肉功能的重复测试之间具有较好的可靠性。同时提示,有必要加强测试程序的标准化、测试前的热身和熟练程序。     

The relationship between lower body strength and obstructed gait in community-dwelling older adults

OBJECTIVES: To determine the relationship between lower body strength of community-dwelling older adults and the time to negotiate obstructed gait tasks. DESIGN: A correlational study. SETTING: The Biomechanics Laboratory, Deakin University, Australia. PARTICIPANTS: Twenty-nine women and 16 men aged 62 to 88 were recruited using advertisements placed in local newspapers. The participants were independent community dwellers, healthy and functionally mobile. MEASUREMENTS: Maximal isometric strength of the knee extensors and dynamic strength of the hip extensors, hip flexors, hip adductors, hip abductors, knee extensors, knee flexors, and ankle plantar flexors were assessed. The times to negotiate four obstructed gait tasks at three progressively challenging levels on an obstacle course and to complete the course were recorded. The relationship between strength and the crossing times was explored using linear regression models. RESULTS: Significant associations between the seven strength measures and the times to negotiate each gait task and to walk the entire course at each level were obtained (r = -0.38 to -0.55; P < .05). In addition, the percentage of the variance explained by strength (R(2)), consistently increased as a function of the progressively challenging level. This increase was particularly marked for the stepping over task (R(2) = 19.3%, 25.0%, and 27.2%, for levels 1, 2, and 3, respectively) and the raised surface condition (R2 = 17.1%, 21.1%, and 30.8%, for levels 1, 2, and 3, respectively). CONCLUSION: The findings of the study showed that strength is a critical requirement for obstructed locomotion. That the magnitude of the association increased as a function of the challenging levels suggests that intervention programs aimed at improving strength would potentially be effective in helping community-dwelling older adults negotiate environmental gait challenges.     

Hip muscle weakness in individuals with medial knee osteoarthritis

Objective

To compare the strength of the hip musculature in people with symptomatic medial knee osteoarthritis (OA) with asymptomatic controls.

Methods

Eighty‐nine people with knee OA and 23 controls age >50 years were recruited from the community. The maximal isometric strength (torque relative to body mass) of the hip abductors, adductors, flexors, extensors, and internal and external rotators was evaluated using hand‐held dynamometry or a customized force transducer apparatus. Univariate linear models with age and sex included as covariates were used to compare muscle strength between groups.

Results

In people with knee OA, significant strength deficits were evident for all hip muscle groups evaluated (P < 0.05). Compared with controls, strength deficits ranged from 16% (hip extensors) to 27% (hip external rotators) after accounting for differences in sex and age between groups.

Conclusion

People with knee OA demonstrate significant weakness of the hip musculature compared with asymptomatic controls. It is not clear if hip muscle weakness precedes the onset of knee OA or occurs as a consequence of disease. Findings from this study support the inclusion of hip strengthening exercises in rehabilitation programs.     

The effect of age and joint angle on the proportionality of extensor and flexor strength at the knee joint

Functional movements require concerted actions of monoarticular and biarticular agonists and antagonists. Understanding age-related changes of muscle function on performance requires insight in the contributions of different muscles to joint moments. Young and elderly participants performed isometric knee extensions and flexions at combinations of knee and hip joint angles. This approach allowed assessing changes in contribution of monoarticular and biarticular knee joint flexors and extensors. Reduced moments were found for elderly persons (flexors: -43%; extensors: -33%). In the flexor group, this reduction was mainly caused by retardation of the biarticular muscles; in the extensors, by reduced strength of the monoarticular muscles. This age-related reduction of joint moments occurred to be joint angle dependent for the extensors. In the flexor group, the reduction was almost invariant. Due to this difference in joint angle dependence, the proportionality between extensors and flexors varied over joint angles and differed with age. It has been discussed how this is related to changes in performances occurring with age.     

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.     

Effects of long-term resistive training on mobility and strength in older adults with diabetes

BACKGROUND: Strength training has been shown to be beneficial in older adults. However, very little data exist on the effects of strength training in older diabetics. METHODS: 31 community-dwelling older adults with diabetes (mean age = 66.1 years) were randomly assigned to either an exercise (EX) or control (CO) group. The EX group trained the plantar flexors, knee extensors, knee flexors, hip extensors, and hip flexors muscle groups at 50%, 60%, and 70% of 1-repetition maximum, 2.6 days a week, for 24 months. Mobility tests included the timed up and go, 50-foot walk, and walking up and down 8 stairs. Strength and mobility for both groups were evaluated at 6-month intervals. RESULTS: There was a group and time effect as the EX group increased 31.4% (p <.001) in strength for all muscle groups after the first 6 months of training, and the strength gains were retained for the duration of the training intervention. There was also a group and time effect for mobility as performance increased 8.6% and 9.8% (p =.032 and p = 0.031) for the first 6 and 12 months, respectively, but decreased to 4.6% above baseline at the end of the intervention. There were essentially no changes from baseline strength or mobility values for the CO group. CONCLUSION: In conclusion, these data suggest that a moderate-intensity resistive-training program can improve mobility and strength for the duration of a 24-month intervention in older adults with diabetes, thus potentially reducing the rate of mobility loss during aging.     

Relationships among age-associated strength changes and physical activity level, limb dominance, and muscle group in women

This study investigated the magnitude and rate of age-associated strength reductions in Australian independent urban-dwelling women and the relationship to muscle groups, limb dominance, and physical activity level. Independent urban-dwelling women aged 20 to 89 years (N = 217) performed maximal voluntary contractions with the dominant and nondominant knee extensors, plantar flexors, and handgrip. Anthropometric measurements were made and questionnaire responses used to obtain current physical activity levels. Trend analysis within analysis of variance and regression analysis on strength was performed. Limb muscle strength was found to be associated with increased age, muscle group, limb dominance, and activity. Self-reported physical activity levels declined with age but women who were more physically active for their age group were stronger in all muscle groups and had more lean body mass and lean thigh and leg cross-sectional area than relatively inactive women. Slopes of the linear reductions of maximal voluntary strength of the knee extensors, plantar flexors, and handgrip with age were significantly different (p < .05) at 9.3%, 7.4%, and 6.2% per decade, respectively. The limb muscle strength of healthy Australian independent and urban-dwelling women aged 20 to 89 years was found to be associated with age and three aspects of disuse: muscle group, relative levels of physical activity, and limb dominance.     

Muscle strength, endurance, and aerobic capacity in rheumatoid arthritis: a comparative study with healthy subjects.

Isometric/isokinetic muscle strength and isokinetic endurance of the lower extremities as well as aerobic capacity were evaluated in 67 patients (43 female, 24 male; mean age 53 years, range 23-65) with classical/definite rheumatoid arthritis (RA) of functional class II. Results obtained were compared with those of a healthy reference group matched for age and sex. Disease characteristics of the group with RA were registered and lifestyle characteristics, such as work load, exercise, diet, smoking, and alcohol habits, were reported by both groups. Generally, results showed that the group with RA had decreased functional capacity. Isometric hip and knee muscle strength of the rheumatoid group was reduced to about 75% of normal function, isokinetic knee muscle strength at the velocities of 60 and 180 degrees/s to about 65% and 75% of normal function respectively, isokinetic endurance of the knee muscle groups to about 45%, and aerobic capacity to about 80% of the results obtained for the healthy reference group. Analyses of variance showed that the rheumatoid group, compared with the healthy group, had significantly reduced function on all isometric and isokinetic tests of the extensors and flexors of the knee. Results for isometric hip muscle strength were similar--all tests but one yielding highly significant differences. To avoid unnecessary functional deficits it seems important to include muscular training in rehabilitation programmes for patients with RA.     

Age-related differences in the force generation capabilities and tendon extensibilities of knee extensors and plantar flexors in men

BACKGROUND: Recently, the number of elderly individuals who participate in sports has increased, thus injuries from overuse are now becoming recognized in the elderly population. Therefore, it is important to determine which muscle groups and tendons are most affected with aging to plan appropriate exercise interventions for elderly individuals. In particular, muscles and tendons in knee extensors and plantar flexors play an important role during locomotion. The purpose of this study was to compare the knee extensor and plantar flexor muscles and tendons. METHODS: Young (n = 19) and elderly (n = 17) men performed isometric voluntary knee extension and plantar flexion contractions. Muscle thickness and elongation of tendon structures in knee extensors and plantar flexors were measured by ultrasonography. RESULTS: Relative muscle thickness (to limb length) in the elderly group was significantly lower than that in the young group in knee extensors (p <.001), although no significant difference was found between the two groups in plantar flexors (p =.063). Relative muscle strength (to body mass) in the elderly group was significantly lower than that in the young group in both sites (all p <.001). Ratio of muscle strength to muscle thickness in the elderly group was significantly lower than that in the young group in plantar flexors, but not in knee extensors. The elderly group had significantly lower maximal elongation and strain of tendon structures in both sites than the young group had. CONCLUSION: These results suggest that the age-related weakness in knee extensors may be attributed to muscle atrophy, whereas that in plantar flexors is not, and that elderly persons have less extensible tendon structures in both sites.     

Hand grip strength is strongly associated with lower limb strength but only weakly with postural control in community-dwelling older adults

BackgroundHand grip strength is frequently used as a measurement of muscle strength, especially among older adults. Muscle strength is only one of the many components in postural control and it is currently unclear to what extent hand grip strength is associated with postural control. The aim was to analyze the association between hand grip strength and lower limb muscle strength, and postural control among older adults.MethodsForty-five community-dwelling individuals over 70 years of age provided isometric hand grip strength and lower limb strength (including hip extension and abduction, knee flexion and extension, and ankle dorsiflexion and plantarflexion), as well as postural control measurements. In the latter, center of pressure excursions were recorded for quiet stance and limits of stability tests on a force plate. Orthogonal projection of latent structures regression models were used to analyze associations between hand grip strength and lower limb strength as well as postural control, respectively.ResultsLower limb strength explained 74.4% of the variance in hand grip strength. All lower limb muscle groups were significantly associated with hand grip strength. In a corresponding model, postural control measured with center of pressure excursions explained 20.7% of the variance in a statistically significant, albeit weak, model.ConclusionsThese results support that hand grip strength is a valid method to estimate lower limb strength among older adults on a group level. However, strength measurements seem insufficient as a substitute for measuring postural control, and therefore specific balance tests are necessary.     

Low plasma carotenoids and skeletal muscle strength decline over 6 years

BACKGROUND: Higher intake of fruits and vegetables appears to protect against inflammation, poor physical performance, and disability, but its relationship with muscle strength is unclear. We examined the association between total plasma carotenoids, an indicator of fruit and vegetable intake, and changes in muscle strength over a 6-year follow-up in the participants aged 65 years and older in the InCHIANTI study, a population-based study in Tuscany, Italy. METHODS: Plasma carotenoids were measured at enrollment (1998-2000). Hip, knee, and grip strength were measured at enrollment and 6 years later (2004-2006) in 628 of the 948 participants evaluated at baseline. Poor muscle strength was defined as the lowest sex-specific quartile of hip, knee, and grip strength at enrollment. The main outcome was poor muscle strength at the 6-year follow-up visit among those participants originally in the upper three quartiles of strength at enrollment. RESULTS: Overall, 24.9% (110/441), 25.0% (111/444), and 24.9% (118/474) participants developed poor hip, knee, and grip strength, respectively. After adjusting for potential confounders, participants in the lowest versus the highest quartile of total plasma carotenoids at enrollment were at higher risk of developing poor hip (odds ratio [OR] = 3.01, 95% CI, 1.43-6.31, p =.004), knee (OR = 2.89, 95% CI, 1.38-6.02, p =.005), and grip (OR = 1.88, 95% CI, 0.93-3.56, p =.07) muscle strength at the 6-year follow-up visit. CONCLUSION: These findings suggest that older community-dwelling adults with lower plasma carotenoids levels, a marker of poor fruit and vegetable intake, are at a higher risk of decline in skeletal muscle strength over time.     

Longitudinal muscle strength changes in older adults: influence of muscle mass, physical activity, and health

The longitudinal changes in isokinetic strength of knee and elbow extensors and flexors, muscle mass, physical activity, and health were examined in 120 subjects initially 46 to 78 years old. Sixty-eight women and 52 men were reexamined after 9.7 +/- 1.1 years. The rates of decline in isokinetic strength averaged 14% per decade for knee extensors and 16% per decade for knee flexors in men and women. Women demonstrated slower rates of decline in elbow extensors and flexors (2% per decade) than men (12% per decade). Older subjects demonstrated a greater rate of decline in strength. In men, longitudinal rates of decline of leg muscle strength were approximately 60% greater than estimates from a cross-sectional analysis in the same population. The change in leg strength was directly related to the change in muscle mass in both men and women, and it was inversely related to the change in medication use in men. Physical activity declined yet was not directly associated with strength changes. Although muscle mass changes influenced the magnitude of the strength changes over time, strength declines in spite of muscle mass maintenance or even gain emphasize the need to explore the contribution of other cellular, neural, or metabolic mediators of strength changes.     

The interrelationship among muscle mass, strength, and the ability to perform physical tasks of daily living in younger and older women

The purpose of this study was to objectively compare the difficulty and determine the contribution of strength and muscle mass to the performance of physical tasks of daily living in a group of younger and older women. A cross-sectional design was used. Volunteer participants were from the community of Birmingham, AL; there were 21 older (aged 60-75 years) and 20 younger (23-34 years) healthy women in the study. Subjects were matched for height and weight. Their testing included total and regional body composition evaluation by use of dual-energy x-ray absorptiometry, isometric strength tests of elbow flexors and knee extensors, and integrated electromyography (IEMG) evaluation while the subjects were standing from and sitting into a chair, and while they were carrying a small load (weight relative to strength). A two-way analysis of variance and a two-way analysis of covariance with repeated measures, Pearson product correlation, and first-order partial correlations were used to analyze the data. A significant inverse correlation was observed between age and isometric strength of both the knee extensors and elbow flexors. Adjusting for upper leg lean tissue did not change the significant inverse correlation between age and knee extensor strength. However, after an adjustment for arm lean tissue, there was no significant correlation between elbow flexor strength and age. Older women experienced significantly greater difficulty in standing than younger women as measured by quadriceps normalized IEMG (i.e., IEMG during task/IEMG during maximum isometric strength test). This difference persisted even after the covariate upper leg lean tissue was added to the model. No significant difference was observed between younger and older women for difficulty (biceps normalized IEMG) during the carry task after the covariate arm lean tissue was added to the model. The older women in this study had less strength in the knee extensors and experienced greater difficulty standing from a chair than the younger women, even after the covariate upper leg lean tissue was added to the model. This suggests that other factors, in addition to loss of lean tissue, contribute to the age-related decline of muscular strength and the ability to perform tasks with the legs. In contrast, although elbow flexor strength declined, this appeared to be largely due to decreased arm lean tissue mass.     

Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia

OBJECTIVE: To evaluate the short- and long-term efficacy of exercise therapy in a warm, waist-high pool in women with fibromyalgia. METHODS: Thirty-four women (mean +/- SD tender points 17 +/- 1) were randomly assigned to either an exercise group (n = 17) to perform 3 weekly sessions of training including aerobic, proprioceptive, and strengthening exercises during 12 weeks, or to a control group (n = 17). Maximal unilateral isokinetic strength was measured in the knee extensors and flexors in concentric and eccentric actions at 60 degrees /second and 210 degrees /second, and in the shoulder abductors and adductors in concentric contractions. Health-related quality of life (HRQOL) was assessed using the EQ-5D questionnaire; pain was assessed on a visual analog scale. All were measured at baseline, posttreatment, and after 6 months. RESULTS: The strength of the knee extensors in concentric actions increased by 20% in both limbs after the training period, and these improvements were maintained after the de-training period in the exercise group. The strength of other muscle actions measured did not change. HRQOL improved by 93% (P = 0.007) and pain was reduced by 29% (P = 0.012) in the exercise group during the training, but pain returned close to the pretraining level during the subsequent de-training. However, there were no changes in the control group during the entire period. CONCLUSION: The therapy relieved pain and improved HRQOL and muscle strength in the lower limbs at low velocity in patients with initial low muscle strength and high number of tender points. Most of these improvements were maintained long term.     

Isometric grip endurance of healthy elderly men and women

Grip endurance is one of the important prerequisites for good performance of the upper extremity and hence it is important to evaluate it correctly. However, we know little about normal grip endurance, especially for elderly people. The main objective of this study was to examine the age-related changes in grip isometric endurance of healthy community-dwelling elderly people. Two-hundred and eighty-six subjects aged between 60 and 90, were randomly selected from the electoral list of the city of Sherbrooke, Quebec, Canada. Grip relative isometric endurance was evaluated using the Jamar dynamometer. Isometric grip endurance was estimated by the number of seconds a subject could sustain 50% of his/her maximal voluntary grip strength. Contrary to other upper extremity sensorimotor parameters, no grip isometric endurance difference was found with age, in spite of a slight tendency towards a decrease. The women tended to have better scores than the men and endurance of dominant hand is better than the non-dominant. The stability with age could be explained by muscle fiber composition modifications.     

MUSCLE STRENGTH IN HEALTHY PEOPLE AND IN PATIENTS SUFFRING FROM RECENT-ONSET INFLAMMATORY ARTHRIRIS

Neuromuscular function was compared among 20 patients with relativelyrecent onset (symptomatic period 17 ± 24 months) rheumatoidarthritis (RA) (experimental group; EG), and 20 age- and sex-matchedhealthy people (control group; CG).The comparison was repeatedafter a period of 6 months, when 16 patients had carried outprogressive strength training. At baseline maximal grip strengthand maximal dynamic unilateral strength of the knee extensorsin the EG were significantly (P < 0.05) lower in comparisonto the CG. The groups did not differ from each other in maximalisometric strength of the trunk flexors and extensors or theknee extensors. The 6-month dynamic strength training in theEG resulted in significant increases in maximal dynamic strengthof the knee extensors (P < 0.001), in isometric grip strength(P < 0.001) and in isometric strength of the trunk flexors(P < 0.05) and extensors (P < 0.05) to the level of thehealthy controls. Only minor changes took place in explosivestrength and maximal isometric strength of the knee extensors.Erythrocyte sedimentation rate (P < 0.001), Ritchie's articularindex (P < 0.01) and modified health assessment questionnaire(P < 0.01) improved significantly during the training period.The results suggest that inflammatory arthritis decreases dynamicand/or isometric muscle strength in selected muscle groups ofthe body already in the early stages of disease. However, progressivedynamic strength training rapidly increases the neuromuscularperformance capacity of the patients even to the level of healthypeople without detrimental effects on disease activity. KEY WORDS: Recent-onset inflammatory arthritis, Muscle strength, Neuromuscular function, Strength training, Disease activity, Healthy people     

The role of muscle loss in the age-related decline of grip strength: cross-sectional and longitudinal perspectives

The decline of strength with age has often been attributed to declining muscle mass in older subjects. To investigate factors which might influence changes in strength across the life span, grip strength and muscle mass (as estimated by creatinine excretion and forearm circumference) were measured in 847 healthy volunteers, aged 20-100 years, from the Baltimore Longitudinal Study of Aging. Cross-sectional and longitudinal results concur that grip strength increases into the thirties and declines at an accelerating rate after age 40. However, the grip strength of 48% of subjects less than 40 years old, 29% of individuals 40-59 years old, and 15% of subjects older than 60 did not decline during the average 9-year follow-up. Grip strength is strongly correlated with muscle mass (r = .60, p less than .0001). However, using multiple regression analysis, grip strength is more strongly correlated with age (partial r2 = .38) than muscle mass (partial r2 = .16). Additionally, a residuals analysis demonstrates that younger subjects are stronger and older subjects are weaker than one would predict based on their muscular size. Thus, while strength losses are partially explained by declining muscle mass, there remain other yet undetermined factors beyond declining muscle mass to explain some of the loss of strength seen with aging.     

Knee extensor and knee flexor strength: cross-sectional area ratios in young and elderly men.

The relationships between isometric and isokinetic-concentric knee extensor and knee flexor strength, and quadriceps and hamstring cross-sectional area (CSA) were determined in young (n = 13, M = 24.5y) and elderly (n = 12, M = 70.7y) men. Quadriceps and hamstring CSA was determined by computed tomography. Knee extensor and flexor strength at 0 degree/s and 120 degree/s was determined on a Kin-Com isokinetic dynamometer. Compared to the young men, elderly men had significantly smaller quadriceps muscles and were weaker (22-32%) in knee flexion and knee extension at both angular velocities. Strength:CSA ratios were similar at 0 degree/s, but elderly men had decreased ratios for both extensors and flexors at 120 degree/s. Correlations of knee extensor and flexor strength with muscle CSA were significant at both velocities in elderly men, but not at either velocity for the knee flexors in young men. The decrease in isometric strength in elderly men can be accounted for by their decrease in muscle CSA, but their decrease in isokinetic-concentric strength was greater than their loss of CSA. Further study is required to determine the reason for this nonproportional loss of isokinetic-concentric strength.