Rate of force development: physiological and methodological considerations

The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.

Handgrip strength as a predictor of functional, psychological and social health. A prospective population-based study among the oldest old

BACKGROUND

muscle wasting is associated with a detrimental outcome in older people. Muscle strength measurements could be useful as part of a clinical evaluation of oldest old patients to determine who are most at risk of accelerated decline in the near future.

OBJECTIVE

this study aimed to assess if handgrip strength predicts changes in functional, psychological and social health among oldest old.

DESIGN

the Leiden 85-plus Study is a prospective population-based follow-up study.

SUBJECTS

five-hundred fifty-five, all aged 85 years at baseline, participated in the study.

METHODS

handgrip strength was measured with a handgrip strength dynamometer. Functional, psychological and social health were assessed annually. Baseline data on chronic diseases were obtained from the treating physician, pharmacist, electrocardiogram and blood sample analysis.

RESULTS

at age 85, lower handgrip strength was correlated with poorer scores in functional, psychological and social health domains (all, P < 0.001). Lower baseline handgrip strength predicted an accelerated decline in activities of daily living (ADL) and cognition (both, P <or= 0.001), but not in social health (P > 0.30).

CONCLUSION

poor handgrip strength predicts accelerated dependency in ADL and cognitive decline in oldest old. Measuring handgrip strength could be a useful instrument in geriatric practice to identify those oldest old patients at risk for this accelerated decline.

Muscle strength: clinical and prognostic value of hand-grip dynamometry

PURPOSE OF REVIEW

Grip strength measured by dynamometry is well established as an indicator of muscle status, particularly among older adults. This review was undertaken to provide a synopsis of recent literature addressing the clinical and prognostic value of hand-grip dynamometry.

RECENT FINDINGS

Numerous large-scale normative grip strength projects have been published lately. Other recent studies have reinforced the concurrent relationship of grip strength with measures of nutritional status or muscle mass and measures of function and health status. Studies published in the past few years have confirmed the value of grip strength as a predictor of mortality, hospital length of stay, and physical functioning.

SUMMARY

As a whole, the recent literature supports the use of hand-grip dynamometry as a fundamental element of the physical examination of patients, particularly if they are older adults.

Assessment of Lower Limb Muscle Strength and Power Using Hand-Held and Fixed Dynamometry: A Reliability and Validity Study

Introduction

Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power.

Methods

30 healthy young adults (age: 23±5yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change.

Results

Comparison of RFD methods revealed that a peak 200ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31–0.79).

Conclusions

Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.

Outcomes before and after total knee arthroplasty compared to healthy adults

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To measure changes in muscle strength, range of motion, and function from 2 weeks before to 6 months after total knee arthroplasty (TKA) and compare outcomes with data from a control group consisting of healthy adults.

BACKGROUND

Total knee arthroplasty successfully alleviates pain from knee osteoarthritis, but deficits in function can persist long term. How impairments and functional limitations change over the first 6 months after TKA, compared to data from healthy adults, has not been well reported in the literature.

METHODS

Twenty-four patients who underwent a primary unilateral TKA were compared to healthy adults (n = 17). All patients participated in a standardized rehabilitation program following surgery. Isometric quadriceps torque was assessed using an electromechanical dynamometer. Range of motion was measured actively and passively. Functional performance was assessed using the stair-climbing test, timed up-and-go test, 6-minute walk test, and single-limb stance time. Patients underwent testing at 2 weeks preoperatively and at 1, 3, and 6 months postoperatively.

RESULTS

Compared to healthy older adults, patients performed significantly worse at all times for all measures (P<.05), except for single-limb stance time at 6 months (P>.05). One month postoperatively, patients experienced significant losses from preoperative levels in all outcomes. Patients recovered to preoperative levels by 6 months postoperatively on all measures, except knee flexion range of motion, but still exhibited the same extent of limitation they did prior to surgery.

CONCLUSION

The persistent impairments and functional limitations 6 months after TKA with standard rehabilitation suggest that more intensive therapeutic approaches may be necessary to restore function of patients following TKA to the levels of healthy adults.

Diet and its relationship with grip strength in community-dwelling older men and women: the Hertfordshire cohort study

OBJECTIVES

To examine relationships between diet and grip strength in older men and women and to determine whether prenatal growth modifies these relationships.

DESIGN

Cross-sectional and retrospective cohort study.

SETTING

Hertfordshire, United Kingdom.

PARTICIPANTS

Two thousand nine hundred eighty-three men and women aged 59 to 73 who were born and still living in Hertfordshire, United Kingdom.

MEASUREMENTS

Weight at birth recorded in Health Visitor ledgers; current food and nutrient intake assessed using an administered food frequency questionnaire; and grip strength measured using a handheld dynamometer.

RESULTS

Grip strength was positively associated with height and weight at birth and inversely related to age (all P<.001). Of the dietary factors considered in relation to grip strength, the most important was fatty fish consumption. An increase in grip strength of 0.43 kg (95% confidence interval (CI)=0.13-0.74) in men (P=.005) and 0.48 kg (95% CI=0.24-0.72) in women (P<.001) was observed for each additional portion of fatty fish consumed per week. These relationships were independent of adult height, age, and birth weight, each of which had additive effects on grip strength. There was no evidence of interactive effects of weight at birth and adult diet on grip strength.

CONCLUSION

These data suggest that fatty fish consumption can have an important influence on muscle function in older men and women. This raises the possibility that the antiinflammatory actions of omega-3 fatty acids may play a role in the prevention of sarcopenia.

Hand-grip strength cut points to screen older persons at risk for mobility limitation

OBJECTIVES

To determine optimal hand-grip strength cut points for likelihood of mobility limitation in older people and to study whether these cut points differ according to body mass index (BMI).

DESIGN

Cross-sectional analysis of data.

SETTING

Data collected in the Finnish population-based Health 2000 Survey.

PARTICIPANTS

One thousand eighty-four men and 1,562 women aged 55 and older with complete data on anthropometry, hand-grip strength and self-reported mobility.

MEASUREMENTS

Mobility limitation was defined as difficulty walking 0.5 km or climbing stairs. Receiver operating characteristic analysis was used to estimate hand-grip strength cut points for likelihood of mobility limitation.

RESULTS

The overall hand-grip strength cut points for likelihood of mobility limitation were 37 kg (sensitivity 62%; specificity 76%) for men and 21 kg (sensitivity 67%; specificity 73%) for women. The effect of the interaction between hand-grip strength and BMI on mobility limitation was significant in men (P=.02), but no such interaction was observed in women (P=.16). In men, the most-optimal cutoff points were 33 kg (sensitivity 73%; specificity 79%) for normal-weight men, 39 kg (sensitivity 67%; specificity 71%) for overweight men, and 40 kg (sensitivity 57%; specificity 68%) for obese men. In women, BMI-specific hand-grip strength cutoff values was not markedly more accurate than the overall cutoff value.

CONCLUSION

The hand-grip strength test is a useful tool to identify persons at risk of mobility limitation. In men, hand-grip strength cut points for mobility increased with BMI, whereas in women, only one hand-grip strength threshold was identified.

Relationships Between Spasticity, Strength, Gait, and the GMFM-66 in Persons With Spastic Diplegia Cerebral Palsy

OBJECTIVE

To determine the relationships between spasticity, strength, and the functional measures of gait and gross motor function in persons with spastic diplegia cerebral palsy (CP).

DESIGN

Retrospective, cross-sectional study.

SETTING

Hospital clinic.

PARTICIPANTS

Ninety-seven participants (49 boys, 48 girls; mean age+/-standard deviation, 9.11+/-4.8 y) with spastic diplegia CP were tested once.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A KinCom dynamometer was used to objectively measure spasticity (ankle plantarflexors, knee flexors, hip adductors) and maximum strength (ankle dorsiflexors and plantarflexors, knee flexors and extensors, hip abductors and adductors). A gait analysis was conducted to evaluate linear variables (gait speed, stride length, cadence) and kinematic variables (ankle dorsiflexion, foot progression, knee and hip flexion, pelvic tilt at initial contact and ankle dorsiflexion, knee and hip flexion, pelvic tilt, trunk rotation range of motion) during gait. Gross motor function was measured using the Gross Motor Function Measure (GMFM-66) and separately, the GMFM walking, running & jumping dimension. Multiple linear regression analysis was used to determine the relationships between spasticity, strength, gait, and the GMFM (P<.05).

RESULTS

Spasticity did not account for a substantial amount of explained variance in gait and gross motor function (up to 8% for the GMFM walking, running & jumping dimension). Moderate to high correlations existed between strength and gait linear data and function, accounting for up to 69% of the explained variance (strength and GMFM-66, r2=.69).

CONCLUSIONS

For this cohort of participants with spastic diplegia CP who ambulated with or without an assistive device, strength was highly related to function and explained far more of the variance than spasticity. The results may not be generalized to those with more severe forms of CP.

Effect of amino acid supplementation on muscle mass, strength and physical function in elderly

BACKGROUND & AIMS

With advancing age there is a gradual decline in muscle mass, strength and function. The aim of this study was to determine if regular intake of a nutritional supplement containing essential amino acids (EAA)+arginine could reverse these responses in elderly subjects.

METHODS

Twelve glucose intolerant subjects (67.0+/-5.6 (SD) years, 7 females, 5 males) ingested 11 g of EAA+arginine two times a day, between meals for 16 weeks. Diet and activity were not otherwise modified. Lean body mass (DEXA) was measured every fourth week. Maximal leg strength was tested and functional tests were performed at week 0, 8, 12, and 16.

RESULTS

Lean body mass (LBM) increased during the study (p=0.038). At week 12, the average increase in LBM was 1.14+/-0.36 (SE) kg (p<0.05 vs baseline), whereas at week 16, the increase was 0.60+/-0.38 kg (NS vs baseline). The lower extremity strength measure score (sum of individual knee flexors and extensors' one repetition maximum, n=10) was 127.5+/-21.8 kg at baseline, and average increase during the study was 22.2+/-6.1% (p<0.001). Improvements were also observed in usual gait speed (p=0.002), timed 5-step test (p=0.007), and timed floor-transfer test (p=0.022).

CONCLUSION

Supplementation of the diet with EAA+arginine improves lean body mass, strength and physical function compared to baseline values in glucose intolerant elderly individuals.

Drug burden index score and functional decline in older people

BACKGROUND

The Drug Burden Index (DBI), a measure of exposure to anticholinergic and sedative medications, has been independently associated with physical and cognitive function in a cross-sectional analysis of community-dwelling older persons participating in the Health, Aging and Body Composition study. Here we evaluate the association between DBI and functional outcomes in Health, Aging and Body Composition study participants over 5 years.

METHODS

DBI was calculated at years 1 (baseline), 3, and 5, and a measure of the area under the curve for DBI (AUCDB) over the whole study period was devised and calculated. Physical performance was measured using the short physical performance battery, usual gait speed, and grip strength. The association of DBI at each time point and AUCDB with year 6 function was analyzed in data from participants with longitudinal functional measures, controlling for sociodemographics, comorbidities, and baseline function.

RESULTS

Higher DBI at years 1, 3, and 5 was consistently associated with poorer function at year 6. On multivariate analysis, a 1-unit increase in AUCDB predicted decreases in short physical performance battery score of .08 (P=.01), gait speed of .01 m/s (P=.004), and grip strength of .27 kg (P=.004) at year 6.

CONCLUSION

Increasing exposure to medication with anticholinergic and sedative effects, measured with DBI, is associated with lower objective physical function over 5 years in community-dwelling older people.

Impact of whole-body vibration training versus fitness training on muscle strength and muscle mass in older men: a 1-year randomized controlled trial

BACKGROUND

This randomized controlled study investigated the effects of 1-year whole-body vibration (WBV) training on isometric and explosive muscle strength and muscle mass in community-dwelling men older than 60 years.

METHODS

Muscle characteristics of the WBV group (n = 31, 67.3 +/- 0.7 years) were compared with those of a fitness (FIT) group (n = 30, 67.4 +/- 0.8 years) and a control (CON) group (n = 36, 68.6 +/- 0.9 years). Isometric strength of the knee extensors was measured using an isokinetic dynamometer, explosive muscle strength was assessed using a counter movement jump, and muscle mass of the upper leg was determined by computed tomography.

RESULTS

Isometric muscle strength, explosive muscle strength, and muscle mass increased significantly in the WBV group (9.8%, 10.9%, and 3.4%, respectively) and in the FIT group (13.1%, 9.8%, and 3.8%, respectively) with the training effects not significantly different between the groups. No significant changes in any parameter were found in the CON group.

CONCLUSION

WBV training is as efficient as a fitness program to increase isometric and explosive knee extension strength and muscle mass of the upper leg in community-dwelling older men. These findings suggest that WBV training has potential to prevent or reverse the age-related loss in skeletal muscle mass, referred to as sarcopenia.

Lower extremity muscle mass predicts functional performance in mobility-limited elders

OBJECTIVES

This study examined the influence of lower extremity body composition and muscle strength on the severity of mobility-disability in community-dwelling older adults.

METHODS

Fifty-seven older males and females (age 74.2 +/- 7 yrs; BMI 28.9 +/- 6 kg/m2) underwent an objective assessment of lower extremity functional performance, the Short Physical Performance Battery test (SPPB). Participants were subsequently classified as having moderate (SPPB score 7: n = 38) or severe mobility impairments (SPPB score

RESULTS

TLM was a strong independent predictor of the level of functional impairment, after accounting for chronic medical conditions, BMD, body fat, body weight and habitual physical activity. In a separate predictive model, reduced muscle strength was also a significant predictor of severe functional impairment. The severity of mobility-disability was not influenced by gender (p = 0.71). A strong association was elicited between TLM and muscle strength (r = 0.78, p < 0.01).

CONCLUSIONS

These data suggest that lower extremity muscle mass is an important determinant of physical performance among functionally-limited elders. Such findings may have important implications for the design of suitable strategies to maintain independence in older adults with compromised physical functioning. Additional studies are warranted to assess the efficacy of lifestyle, exercise or therapeutic interventions for increasing lean body mass in this population.

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Key Words

• aging
• sarcopenia
• mobility
• muscle mass
• strength

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MESH Headings

• Absorptiometry, Photon
• Activities of Daily Living
• Aged
• Body Composition/physiology
• Bone Density/physiology
• Cross-Sectional Studies
• Exercise Test
• Female
• Health Status
• Humans
• Logistic Models
• Lower Extremity/physiology
• Male
• Mobility Limitation
• Muscle Strength/physiology
• Muscle Strength Dynamometer
• Muscle, Skeletal/anatomy & histology
• Muscle, Skeletal/physiology
• Physical Fitness/physiology
• Randomized Controlled Trials as Topic

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Grants

• M01 RR000533 NCRR NIH HHS
• R01 AG018844 NIA NIH HHS
• M01 RR00533 NCRR NIH HHS
• AG18844 NIA NIH HHS

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Collaborators Collapse

Get a grip: individual variations in grip strength are a marker of brain health

Demonstrations that grip strength has predictive power in relation to a range of health conditions-even when these are assessed decades later-has motivated claims that hand-grip dynamometry has the potential to serve as a "vital sign" for middle-aged and older adults. Central to this belief has been the assumption that grip strength is a simple measure of physical performance that provides a marker of muscle status in general, and sarcopenia in particular. It is now evident that while differences in grip strength between individuals are influenced by musculoskeletal factors, "lifespan" changes in grip strength within individuals are exquisitely sensitive to integrity of neural systems that mediate the control of coordinated movement. The close and pervasive relationships between age-related declines in maximum grip strength and expressions of cognitive dysfunction can therefore be understood in terms of the convergent functional and structural mediation of cognitive and motor processes by the human brain. In the context of aging, maximum grip strength is a discriminating measure of neurological function and brain health.

Promotion of physical fitness and prevention of secondary conditions for children with cerebral palsy: section on pediatrics research summit proceedings

Inadequate physical fitness is a major problem affecting the function and health of children with cerebral palsy (CP). Lack of optimal physical activity may contribute to the development of secondary conditions associated with CP such as chronic pain, fatigue, and osteoporosis. The purpose of this article is to highlight the content and recommendations of a Pediatrics Research Summit developed to foster collaborative research in this area. Two components of physical fitness-muscle strength and cardiorespiratory fitness-were emphasized. Although there is evidence to support the use of physical fitness interventions, there are many gaps in our current knowledge. Additional research of higher quality and rigor is needed in order to make definitive recommendations regarding the mode, intensity, frequency, and duration of exercise. Outcome measurements have focused on the body functions and structures level of the International Classification of Functioning, Disability and Health (ICF), and much less is known about effects at the activities and participation levels. Additionally, the influence of nutritional and growth factors on physical fitness has not been studied in this population, in which poor growth and skeletal fragility have been identified as serious health issues. Current intervention protocols and outcome measurements were critically evaluated, and recommendations were made for future research.

Prevalence and correlates of frailty among community-dwelling older men and women: findings from the Hertfordshire Cohort Study

BACKGROUND

frailty, a multi-dimensional geriatric syndrome, confers a high risk for falls, disability, hospitalisation and mortality. The prevalence and correlates of frailty in the UK are unknown.

METHODS

frailty, defined by Fried, was examined among community-dwelling young-old (64-74 years) men (n = 320) and women (n = 318) who participated in the Hertfordshire Cohort Study, UK.

RESULTS

the prevalence of frailty was 8.5% among women and 4.1% among men (P = 0.02). Among men, older age (P = 0.009), younger age of leaving education (P = 0.05), not owning/mortgaging one's home (odds ratio [OR] for frailty 3.45 [95% confidence interval {CI} 1.01-11.81], P = 0.05, in comparison with owner/mortgage occupiers) and reduced car availability (OR for frailty 3.57 per unit decrease in number of cars available [95% CI 1.32, 10.0], P = 0.01) were associated with increased odds of frailty. Among women, not owning/mortgaging one's home (P = 0.02) was associated with frailty. With the exception of car availability among men (P = 0.03), all associations were non-significant (P > 0.05) after adjustment for co-morbidity.

CONCLUSIONS

frailty is not uncommon even among community-dwelling young-old men and women in the UK. There are social inequalities in frailty which appear to be mediated by co-morbidity.

Loss of knee-extension strength is related to knee swelling after total knee arthroplasty

OBJECTIVE

To examine whether changes in knee-extension strength and functional performance are related to knee swelling after total knee arthroplasty (TKA).

DESIGN

Prospective, descriptive, hypothesis-generating study.

SETTING

A fast-track orthopedic arthroplasty unit at a university hospital.

PARTICIPANTS

Patients (N=24; mean age, 66y; 13 women) scheduled for primary unilateral TKA were investigated 1 week before surgery and on the day of hospital discharge 2.4 days postsurgery.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

We assessed all patients for knee-joint circumference, knee-extension strength, and functional performance using the Timed Up & Go, 30-second Chair Stand, and 10-m fast speed walking tests, together with knee pain during all active test procedures.

RESULTS

All investigated variables changed significantly from pre- to postsurgery independent of knee pain. Importantly, knee circumference increased (knee swelling) and correlated significantly with the decrease in knee-extension strength (r=-.51; P=.01). Reduced fast-speed walking correlated significantly with decreased knee-extension strength (r=.59; P=.003) and decreased knee flexion (r=.52; P=.011). Multiple linear regression showed that knee swelling (P=.023), adjusted for age and sex, could explain 27% of the decrease in knee-extension strength. Another model showed that changes in knee-extension strength (P=.009) and knee flexion (P=.018) were associated independently with decreased performance in fast-speed walking, explaining 57% of the variation in fast-speed walking.

CONCLUSIONS

Our results indicate that the well-known finding of decreased knee-extension strength, which decreases functional performance shortly after TKA, is caused in part by postoperative knee swelling. Future studies may look at specific interventions aimed at decreasing knee swelling postsurgery to preserve knee-extension strength and facilitate physical rehabilitation after TKA.

Hand span influences optimal grip span in male and female teenagers

PURPOSE

To determine if there is an optimal grip span for determining the maximum handgrip strength in male and female teenagers, and if the optimal grip span was related to hand span. If they are related then the second aim was to derive a mathematic equation relating hand span and optimal grip span.

METHODS

One hundred healthy teenage boys (15.1 +/- 1.1 y) and 106 girls (15.4 +/- 1.3 y) were evaluated (age range, 13-18 y). Each hand was randomly tested on 10 occasions using 5 different grip spans, allowing a 1-minute rest between attempts. The hand span was measured from the tip of the thumb to the tip of the small finger with the hand opened as wide as possible.

RESULTS

The results showed that an optimal grip span to determine the maximum handgrip strength was identified for both genders, and the optimal grip span and hand span correlated in both genders.

CONCLUSIONS

The results suggest that there is an optimal grip span to which the dynamometer should be adjusted when measuring handgrip strength in teenagers. The optimal grip span was influenced by hand span in both genders. For males the optimal grip span can be derived from the equation y = x/7.2 + 3.1 cm, and for females from the equation y = x/4 + 1.1 cm. where y is the optimal grip span and x is the hand-span. These equations may improve the reliability and accuracy of the results and may guide clinicians and researchers in selecting the optimal grip span on the hand dynamometer when measuring handgrip strength in teenagers.

The reliability of one vs. three grip trials in symptomatic and asymptomatic subjects

Grip strength is used in the assessment of hand and upper limb function. Current recommendations state that taking the mean of three repeated grip trials provides more reliable results than only one trial. A repeated measures, crossover design was used. Sixty-six subjects were recruited (22 asymptomatic subjects, 22 following carpal tunnel decompression, and 22 following flexor tendon repair). Grip strength testing was performed on a Jamar dynamometer using a standardized testing protocol. Pre- and post testing pain levels were recorded using a verbal analogue scale. Each subject's grip strength was tested four times, twice using a single trial protocol and twice using three grip trials in random order. Intraclass correlation coefficients (ICC) (2,1), 95% confidence intervals, and standard error of measurements were calculated. A two-tailed paired samples t-test was used to investigate the difference between the grip strength values obtained and the changes in verbal analogue scale. High levels of test-retest reliability (ICC>or=0.85) were found for the three methods of grip strength testing (one trial, the mean of three trials, and the best of three trials). The mean values of grip strength generated for each method of grip strength testing produced comparable results. A significant difference (p>or=0.0001) was observed in the verbal analogue scale scores following one trial and three in all three sample groups. Clinically acceptable levels of reliability (>or=0.91) were demonstrated by all three methods of grip strength testing other than the mean of three trials for the asymptomatic group. Distribution of the ICC results and the elevated verbal analogue scales associated with three trials suggest that the use of one grip trial may be appropriate. This study suggests that one maximal trial is as reliable as and less painful than either the best of, or, mean of three trials.

Correlates of Life Space in a Volunteer Cohort of Older Adults

The authors measured the spatial extent of movement of older persons (i.e., life space) and examined factors that are related to life space. A larger life space was positively correlated with self-report measures of disability. In generalized logit models adjusted for demographics and time of year, a larger life space was associated with less visual impairment, higher levels of lower extremity motor performance, global cognition, and social involvement, and with personality and purpose in life. The results suggest that the range of environmental movement in older adults is a useful indicator of health in old age and may complement measures of disability.

Effectiveness of loaded sit-to-stand resistance exercise for children with mild spastic diplegia: a randomized clinical trial

OBJECTIVE

To investigate effectiveness of a functional strengthening program, the loaded sit-to-stand (STS) resistance exercise, for children with cerebral palsy (CP).

DESIGN

A single-blind, randomized block design.

SETTING

STS exercises were carried out at the children's homes.

PARTICIPANTS

Twenty children (12 boys, 8 girls; age range, 5-12y) with spastic diplegia CP and classified by the Gross Motor Function Classification System as level I or II were stratified by their severity and age and randomly allocated into either the experimental or control group.

INTERVENTION

Both groups received their regular physical therapy. The experimental group underwent loaded STS exercise 3 times a week for 6 weeks.

MAIN OUTCOME MEASURES

Goal dimension scores of the Gross Motor Function Measure (GMFM), gait speed, 1 repetition maximum (1-RM) of the loaded STS, isometric strength of knee extensor, and Physiological Cost Index (PCI). The outcome measures were conducted at the beginning and end of the 6-week study.

RESULTS

After loaded STS exercise, the experimental group showed statistically significant differences in GMFM goal dimension scores, 1-RM STS, and PCI from the control group. The changes in gait speed and isometric strength of the knee extensor did not differ significantly between the 2 groups.

CONCLUSIONS

After the loaded STS exercise, children with mild spastic diplegia improved their basic motor abilities, functional muscle strength, and walking efficiency.

Strong or Weak Handgrip? Normative Reference Values for the German Population across the Life Course Stratified by Sex, Age, and Body Height

Handgrip strength is an important biomarker of healthy ageing and a powerful predictor of future morbidity and mortality both in younger and older populations. Therefore, the measurement of handgrip strength is increasingly used as a simple but efficient screening tool for health vulnerability. This study presents normative reference values for handgrip strength in Germany for use in research and clinical practice. It is the first study to provide normative data across the life course that is stratified by sex, age, and body height. The study used a nationally representative sample of test participants ages 17–90. It was based on pooled data from five waves of the German Socio-Economic Panel (2006–2014) and involved a total of 11,790 persons living in Germany (providing 25,285 observations). Handgrip strength was measured with a Smedley dynamometer. Results showed that peak mean values of handgrip strength are reached in men’s and women’s 30s and 40s after which handgrip strength declines in linear fashion with age. Following published recommendations, the study used a cut-off at 2 SD below the sex-specific peak mean value across the life course to define a ‘weak grip’. Less than 10% of women and men aged 65–69 were classified as weak according to this definition, shares increasing to about half of the population aged 80–90. Based on survival analysis that linked handgrip strength to a relevant outcome, however, a ‘critically weak grip’ that warrants further examination was estimated to commence already at 1 SD below the group-specific mean value.

Midlife muscle strength and human longevity up to age 100 years: a 44-year prospective study among a decedent cohort

We studied prospectively the midlife handgrip strength, living habits, and parents' longevity as predictors of length of life up to becoming a centenarian. The participants were 2,239 men from the Honolulu Heart Program/Honolulu-Asia Aging Study who were born before the end of June 1909 and who took part in baseline physical assessment in 1965-1968, when they were 56-68 years old. Deaths were followed until the end of June 2009 for 44 years with complete ascertainment. Longevity was categorized as centenarian (≥100 years, n = 47), nonagenarian (90-99 years, n = 545), octogenarian (80-89 years, n = 847), and ≤79 years (n = 801, reference). The average survival after baseline was 20.8 years (SD = 9.62). Compared with people who died at the age of ≤79 years, centenarians belonged 2.5 times (odds ratio (OR) = 2.52, 95% confidence interval (CI) = 1.23-5.10) more often to the highest third of grip strength in midlife, were never smokers (OR = 5.75 95% CI = 3.06-10.80), had participated in physical activity outside work (OR = 1.13 per daily hour, 95% CI = 1.02-1.25), and had a long-lived mother (≥80 vs. ≤60 years, OR = 2.3, 95% CI = 1.06-5.01). Associations for nonagenarians and octogenarians were parallel, but weaker. Multivariate modeling showed that mother's longevity and offspring's grip strength operated through the same or overlapping pathway to longevity. High midlife grip strength and long-lived mother may indicate resilience to aging, which, combined with healthy lifestyle, increases the probability of extreme longevity.

Sarcopenia and cognitive impairment in elderly women: results from the EPIDOS cohort

BACKGROUND

common pathophysiological pathways are shared between age-related body composition changes and cognitive impairment.

OBJECTIVE

evaluate whether current operative sarcopenia definitions are associated with cognition in community-dwelling older women.

DESIGN

cross-sectional analyses.

SUBJECTS

a total of 3,025 women aged 75 years and older.

MEASUREMENTS

body composition (assessed by dual energy X-ray absorptiometry) and cognition (measured by short portable mental status questionnaire) were obtained in all participants. Multivariate logistic regression models assessed the association of six operative definitions of sarcopenia with cognitive impairment. Gait speed (GS, measured over a 6-meter track at usual pace) and handgrip strength (HG, measured by a hand-held dynamometer) were considered additional factors of interest.

RESULTS

a total of 492 (16.3%) women were cognitively impaired. The prevalence of sarcopenia ranged from 3.3 to 18.8%. No sarcopenia definition was associated with cognitive impairment after controlling for potential confounders. To proof consistency, the analyses were performed using GS and HG, two well-established predictors of cognitive impairment. Low GS [odds ratio (OR) 2.42, 95% confidence interval (CI) 1.72-3.40] and low HG (OR: 1.81, 95% CI: 1.33-2.46) were associated with cognitive impairment.

CONCLUSION

no significant association was evidenced between different operative sarcopenia definitions and cognitive impairment. The study suggests that the association between physical performance and cognitive impairment in not mediated by sarcopenia.