Predictors of change in walking velocity in older adults

A Randomized, Double-Blind, Controlled Trial Assessing If Medium-Chain Triglycerides in Combination with Moderate-Intensity Exercise Increase Muscle Strength in Healthy Middle-Aged and Older Adults

An adequate nutritional intake is recommended for the prevention of physical frailty and sarcopenia. In particular, medium-chain fatty acids (MCFAs) are reportedly important for muscle strength in nursing home residents. However, the effects of MCFAs on healthy adults at risk for frailty remain unknown. Hence, a randomized, placebo-controlled study was conducted to investigate the effects of 12 weeks of medium-chain triglycerides (MCTs) intake and walking on muscle mass and function in healthy, sedentary, middle-aged and older adults with a low body mass index. Three MCT intake groups with different amounts of octanoic and decanoic acid intake were compared with a control group. After 12 weeks, knee extension strength increased in all groups, with the increases in all MCT intake groups being significantly higher than those in the control group (p < 0.05). Grip strength significantly increased from baseline in the MCT 6 g/day intake group (p < 0.05). The combination of aerobic exercise and MCT intake may be effective in preventing decline in muscle strength and promoting increase in muscle strength as they can improve muscle energy production, thereby contributing to the maintenance of good health for middle-aged and older adults at high risk for frailty and sarcopenia.

Gait Characteristics of Dynapenia, Sarcopenia, and Presarcopenia in Community-Dwelling Japanese Older Women: A Cross-Sectional Study

Age-related decline in skeletal muscle mass and function are risk factors for reduced walking ability. This study aimed to understand the characteristic gait parameters of presarcopenia (low muscle mass only), dynapenia (low muscle function only), and sarcopenia (low muscle mass and function), which have differing skeletal muscle characteristics. Skeletal muscle mass, grip strength, and gait parameters (walking speed, cadence, step length, step width, gait angle, foot angle, stance time, swing time, and double stance time) were evaluated in 307 older Japanese women. Low muscle function was determined by grip strength and normal walking speed. Participants were assessed and divided into the normal (60.9%, n = 187), presarcopenia (25.7%, n = 79), dynapenia (5.2%, n = 16), and sarcopenia (8.1%, n = 25) groups. When compared to the normal group, the sarcopenia group had significantly slower walking speed and shorter step length (p < 0.05); the dynapenia group had significantly slower walking speed, smaller cadence, shorter step length, wider step width, and longer stance time (p < 0.05); and the presarcopenia group showed no differences. Skeletal muscle function may therefore be more strongly related to reduced walking function in older adults than body composition factors. The decrease in walking function was most pronounced in older women with dynapenia.

Age-Related Change in Muscle Characteristics and Resistance Training for Older Adults

In older adults, muscle weakness contributes greatly to functional restrictions on daily living activities, increased risk of falls, and adverse physiological changes. It has been suggested that not only muscle mass but also muscular infiltration of noncontractile elements may influence muscular performance such as strength and rapid force production. It is proved that resistance training may provoke substantial increases in muscle size even if it is performed at low intensities in older individuals. Also, recent studies have demonstrated the effectiveness of resistance training on muscle quality such as muscular infiltration of noncontractile elements for older people. This review shows the age-related changes in muscle mass and muscle quality, which were measured by muscle echo intensity on ultrasound images, and low-intensity resistance training effects on muscle volume and muscle quality.

Comparative Analysis of High-Velocity Versus Low-Velocity Exercise on Outcomes After Total Knee Arthroplasty: A Randomized Clinical Trial

BACKGROUND AND PURPOSE

High-velocity (HV) exercise is defined as performing a concentric muscle contraction as fast as possible, or in 1 second or less. Low-velocity (LV) exercise is defined as using 2 seconds to complete the contraction. A comparison of HV to LV exercise performed by community dwelling older adults indicates that HV exercise produces greater gains in power and scores for the 8-ft up-and-go, 30-seond chair stand, and continuous scale physical function performance tests. The effectiveness of HV strengthening exercises has not been identified for individuals who undergo total knee arthroplasty (TKA). The purpose of this research study was to compare the effects of a 6-week exercise program, using either LV or HV contractions, on functional performance, gait, and pain of individuals who have undergone TKA.

METHODS

Adults aged 60 to 89 years with a mean (standard deviation) age of 71.2 (6.8) years who underwent TKA an average of 15 days prior were randomly assigned to an HV exercise (n = 19) or LV exercise (n = 19) training group. The training program lasted for 12 sessions, over 6 to 7 weeks. The primary outcome was functional performance rated with the 6-Minute Walk Test. Secondary measures were the stair climb test, Timed Up and Go test, gait velocity, gait deviations measured with the Gait Abnormality Rating Scale, and pain via a visual analog scale. A 2×2 mixed model analysis of variance (group × time) was used for all outcomes. Comparison between LV and HV groups for posttest gait velocity and Gait Abnormality Rating Scale used independent t test and Mann-Whitney U test, respectively.

RESULTS

At baseline no differences between groups were noted for sex, age, and height. The LV group weighed more and had more comorbid conditions. Spearman's ρ demonstrated that the greater comorbidities of the LV group correlated with a slower stair climb test at baseline. At posttest both groups exhibited significantly improved scores for all outcome measurements except the visual analog scale for pain. The HV group, but not the LV group, reported a significant decrease in pain at the end of the 6-week training program.

CONCLUSIONS

Both HV and LV progressive exercises equally improve functional performance. Only the HV group reported significantly decreased pain at posttest.

The relationship between mitochondrial function and walking performance in older adults with a wide range of physical function

BACKGROUND

Age related declines in walking performance may be partly attributable to skeletal muscle mitochondrial dysfunction as mitochondria produce over 90% of ATP needed for movement and the capacity for oxidative phosphorylation decreases with age.

METHODS

Participants were from two studies: an ancillary to the Lifestyle Interventions and Independence for Elders (LIFE) Study (n=33), which recruited lower functioning participants (Short Physical Performance Battery [SPPB], 7.8±1.2), and the Study of Energy and Aging-Pilot (SEA, n=29), which enrolled higher functioning (SPPB, 10.8±1.4). Physical activity was measured objectively using the Actigraph accelerometer (LIFE) and SenseWear Pro armband (SEA). Phosphocreatine recovery following muscle contraction of the quadriceps was measured using (31)P magnetic resonance spectroscopy and ATPmax (mM ATP/s) was calculated. Walking performance was defined as time (s) to walk 400m at a usual-pace. The cross-sectional association between mitochondrial function and walking performance was assessed using multivariable linear regression.

RESULTS

Participants were 77.6±5.3years, 64.2% female and 67.2% white. ATPmax was similar in LIFE vs. SEA (0.52±0.14 vs. 0.55±0.14, p=0.31), despite different function and activity levels (1.6±2.2 vs.77.4±73.3min of moderate activity/day, p<0.01). Higher ATPmax was related to faster walk-time in SEA (r(2)=0.19, p=0.02,); but not the LIFE (r(2)<0.01, p=0.74) cohort.

CONCLUSIONS

Mitochondrial function was associated with walking performance in higher functioning, active older adults, but not lower functioning, sedentary older adults.

Relations of morale and physical function to advanced activities of daily living in health promotion class participants

[Purpose] The aim of this study was to clarify the relations of morale and physical function to the presence/absence of advanced activities of daily living. [Subjects] The subjects were 86 elderly community residents participating in health promotion classes. [Methods] A questionnaire survey on age, gender, presence/absence of advanced activities of daily living, and Philadelphia Geriatric Center Morale Scale score was conducted, in addition to assessment of fitness, consisting of measurement of height, body weight, grip and knee extensor muscle strength, functional reach, one-leg standing time, and Timed Up and Go test. Furthermore, multiple logistic regression analysis was performed with the presence/absence of advanced activities of daily living as a dependent variable. [Results] Grip strength and Timed Up and Go time were identified as variables influencing the presence/absence of advanced activities of daily living. [Conclusion] Physical function represented by grip strength and Timed Up and Go time was higher among subjects performing advanced activities of daily living.

Age-related changes in inter-joint coordination during walking

Existing methods to assess inter-joint coordination in human walking have several important weaknesses. These methods are unable to define 1) the instantaneous changes in coordination within the stride cycle, 2) coordination between multiple joints, or 3) the coupling strength of joint rotations rather than their phase relationships. The present paper introduces a new method called generalized wavelet coherence analysis (GWCA) that solves these three fundamental limitations of previous methods. GWCA combines wavelet coherence analysis with a matrix correlation method to define instantaneous correlation coefficients as the coupling strength for an arbitrary number of joint rotations. The main purpose of the present study is to develop GWCA to quantify inter-joint coordination and thereby assess age-related differences in the coordination of human gaits. Nine young and 19 healthy older persons walked 5 min on a treadmill at three different gait speeds. Joint rotations of the lower extremities were assessed by a Vicon three-dimensional motion capture system. The main results indicated that the older group had significant weaker correlations (t-tests: P < 0.0001) in the preswing phase compared with the younger group for all gait speeds. The age-related differences in inter-joint coordination were more pronounced than the age-related differences in rotations of the individual joints. The intra-stride changes in inter-joint coordination were in agreement with recent findings of intra-stride modulations in neural activity in the sensorimotor cortex. Thus change in the inter-joint coordination assessed by GWCA might be an early indicator of functional decline.

Physical performance and disability in schizophrenia

Despite 50 years of pharmacological and psychosocial interventions, schizophrenia remains one of the leading causes of disability. Schizophrenia is also a life-shortening illness, caused mainly by poor physical health and its complications. The end result is a considerably reduced lifespan that is marred by reduced levels of independence, with few novel treatment options available.

Disability is a multidimensional construct that results from different, and often interacting, factors associated with specific types and levels of impairment. In schizophrenia, the most poignant and well characterized determinants of disability are symptoms, cognitive and related skills deficits, but there is limited understanding of other relevant factors that contribute to disability. Here we conceptualize how reduced physical performance interacts with aging, neurobiological, treatment-emergent, and cognitive and skills deficits to exacerbate ADL disability and worsen physical health. We argue that clearly defined physical performance components represent underappreciated variables that, as in mentally healthy people, offer accessible targets for exercise interventions to improve ADLs in schizophrenia, alone or in combination with improvements in cognition and health. And, finally, due to the accelerated aging pattern inherent in this disease – lifespans are reduced by 25 years on average – we present a training model based on proven training interventions successfully used in older persons. This model is designed to target the physical and psychological declines associated with decreased independence, coupled with the cardiovascular risk factors and components of the metabolic syndrome seen in schizophrenia due to their excess prevalence of obesity and low fitness levels.

Effects of hydraulic-resistance exercise on strength and power in untrained healthy older adults

The purpose of this study was to determine the efficacy of hydraulic-resistance exercise (HDRE) in improving strength and power in healthy older adults. Thirty-nine older adults (68.6 ± 4.9 years; 15 men, 24 women) were divided into a training group or control group (CON). Hydraulic-resistance exercise consisted of a 12-week supervised program, 50 min · d(-1), 3 d · wk(-1). Hydraulic-resistance exercise was used for 10 exercises: Chest press and pull, shoulder press and pull, low back flexion and extension squat, leg adduction/abduction, leg press, and elbow extension/flexion. The number of the sets and the hydraulic-resistance dial setting (D) were gradually increased in 3 stages during the 12-week program. Strength, rating of perceived exertion, and relative intensity during exercise increased significantly from stage to stage whereas repetition velocity decreased. Total work was higher in the second stage compared with the first but lower in the final stage because of reduced repetitions. Peak torque at D2 and D11 increased (p < 0.05) for knee extension (58 and 9%) and flexion (94 and 21%), chest press (35 and 12%) and pull (29 and 14%), shoulder press (14 and 18%) and pull (75 and 18%), and low back flexion (59 and 46%) and extension (84 and 34%). Peak power at D2 and D11 also increased (p < 0.05) for knee extension (140 and 26%) and flexion (96 and 36%), chest press (54 and 28%) and pull (62 and 23%), shoulder press (55 and 31%) and pull (159 and 30%), and low back flexion (177 and 127%) and extension (104 and 66%). There were no significant changes in the CON. Hydraulic-resistance exercise elicits significant improvements in strength and power in older adults. Therefore, HDRE is an effective form of resistance training that provides benefits using low and moderate intensity of training for older adults.

Declines in physical performance by sex and age among nondisabled community-dwelling older Japanese during a 6-year period

Background

Few studies have examined whether declines over time in hand-grip strength (HGS) and fast walking speed (FWS) differ by sex and age among non-Western community-dwelling older adults. This study aimed to quantify changes in HGS and FWS over the 6-year period from 1994 to 2000 and examine whether these changes differed by sex and baseline age among older individuals in a Japanese community.

Methods

We conducted a community-based prospective cohort study. The participants were 513 nondisabled men and women aged 67 to 91 years at the 1994 survey. Independent variables regarding time since baseline, in addition to various time-dependent and time-independent covariates, were obtained in 1994, 1996, 1998, and 2000. The outcome variables were HGS and FWS assessed at each survey. All data on independent and dependent variables that were collected at each survey were simultaneously analyzed using a linear mixed-effects model.

Results

The linear mixed-effects model revealed significant declines in both HGS (−0.70 kg/year, P < 0.001) and FWS (−0.027 m/sec/year, P < 0.001) among nondisabled older participants who had analyzable data in any survey during the 6-year period. Sex was significantly associated with the rate of decline in HGS (P < 0.001), but not FWS (P = 0.211).

Conclusions

In this analysis of nondisabled older Japanese, a mixed-effects model confirmed a significant effect of aging on declines in HGS and FWS and showed that men had a significantly steeper decline in HGS than did women during a 6-year period.

Quadriceps strength and executive functions in older women

OBJECTIVE

The aim of this study is to answer the question whether the strength of the knee extensor musculus quadriceps (m. quadriceps), in particular, is related to specific executive functions and whether this relationship is independent of aerobic fitness. The clinical relevance of this question is that the m. quadriceps can still be trained in older people and executive functions are the most vulnerable to processes of aging.

DESIGN

In 41 cognitively intact older women, cognitive functioning was assessed by neuropsychological tests; isometric and isotonic quadriceps strength by the Quadrisotester and the 30-sec chair-stand test, respectively; and aerobic fitness by the 6-min walk test.

RESULTS

A significant proportion of the total variance of the executive functions, attention/working memory and inhibition, were explained by isometric/isotonic knee extensor strength and aerobic fitness, respectively. Extensor muscle strength, aerobic fitness, or one or more interactions did not explain a significant proportion of the total variance of other cognitive functions.

CONCLUSIONS

These data suggest that in older women, quadriceps strength is associated with the executive function, attention/working memory, and that this effect is independent of aerobic fitness, which seems to be associated more strongly with inhibition, another executive function.

Mobility performance and its sensory, psychomotor and musculoskeletal determinants from age 75 to age 80

BACKGROUND AND AIMS

Prospective studies on the simultaneous effects of multiple determinants on objectively assessed mobility are few. The aim of this study was to analyse mobility performance, its stability and sensory, psychomotor and musculoskeletal determinants in an older population from age 75 to age 80.

METHODS

Sixty-three men and 121 women aged 75 participated at baseline and, five years later, in the follow-up phase of this population-based prospective study. Maximal walking speed and step-mounting height were assessed at baseline and follow-up. Maximal isometric knee extension strength, standing balance on force platform, reaction time, visual acuity and limitations in range of motion (ROM) of hips and knees were assessed at baseline. Structural equation modeling was used to analyse the associations.

RESULTS

The stability of mobility performance from baseline to the five-year follow- up was high (coefficient 0.80 in men, 0.78 in women). In men, knee extension strength, standing balance, ROM limitations and visual acuity explained 69% of the variation in mobility performance at baseline and, indirectly, 59% of that variation at follow-up. Among women, knee extension strength, standing balance, visual acuity and reaction time explained 52% of the variation of mobility performance at baseline and, indirectly, 30% at the five-year follow-up.

CONCLUSIONS

Results indicate that the predictive effects of sensory, psychomotor and musculoskeletal functions on mobility performance extend over five years in older people. In seeking to prevent mobility limitations, vision, reaction time and lower extremity ROM need to be targeted, in addition to muscle strength and balance.

Hip fractures among elderly women: longitudinal comparison of physiological function changes and health care utilization

OBJECTIVE

To compare physiological and functional impairments and their impact on health care use patterns among disabled older women with and without hip fracture.

METHODS

Data from the 3-year longitudinal Women's Health and Aging Study I (WHAS-I) and Medicare Current Beneficiaries Survey (MCBS) were used for this comparison study. Outcome variables include physiological measures (eg, hip and knee strength, functional reach), functional impairments (ADLs, IADLs), and health care use (physician visits). Generalized Estimation Equation (GEE) models were used to examine the differences between groups on physiological and functional change and health service use over time.

RESULTS

Three-year crude mortality rates were significantly higher in the hip fracture group (25%) than in the comparison group (18%); however, statistical significance did not persist after adjusting for age, race, education, living arrangement, depression, and comorbidity (RR = 1.5; P = .17). All physiological and functional measures deteriorated over time, regardless of presence or absence of hip fractures. After adjusting for covariates, the fracture group was significantly worse in knee strength (beta = -0.91; P = .01), usual walking speed (beta = -0.04; P = .01) and rapid walking speed (beta = -0.05; P = .02), and worse IADL function (beta = 0.26; P = .002) than the non-hip fracture group. The rate of additional impairment for both hip fracture group and non-hip fracture group was 0.013 IADL units per month (P = .001). However, there were no significant differences in health care use between the groups.

CONCLUSION

In spite of worse physiological and IADL impairments, once the women recovered from hip fracture surgery, they did not necessarily use more health care resources than non-hip fracture patients. To prevent functional deterioration, interventions need to focus on knee strength and mobility training.

Low serum 25-hydroxyvitamin D levels associated with falls among Japanese community-dwelling elderly

Previous studies have shown that low serum 25-hydroxyvitamin D [25(OH)D] level is a risk factor for falls among the elderly in European and North American populations. We used a cross-sectional community-based survey to study the association of serum 25(OH)D level and falls among Japanese community-dwelling elderly. A total of 2957 elderly persons (950 men and 2007 women) 65-92 yr of age who participated in mass health examinations for the prevention of geriatric syndrome for the elderly underwent an interview, blood analysis, and physical performance testing. Experience of falls over the previous year was assessed in an interview. Physical performance tests of handgrip strength, stork standing time with the eyes open, and normal waking speed as risk factors for falls among the elderly were conducted. Serum albumin and 25(OH)D concentrations were analyzed. Mean 25(OH)D concentration was significantly lower in women than in men (p < 0.001). Women showed a significant decline of 25(OH)D level with increased age (p < 0.001). There was also a significant difference in the prevalence of 25(OH)D insufficiency [25(OH)D level < 20 ng/ml] between the sexes (p < 0.001). The rate of falls was significantly higher in the lowest quartile of 25(OH)D level in women (p = 0.02) and in women with 25(OH)D insufficiency (p = 0.001). Women also showed significant declines in all three fall-related physical performance tests. Multiple logistic regression analysis showed significant and independent associations between 25(OH)D level and experience of falls in women only (p = 0.01). Low 25(OH)D level was significantly associated with a high prevalence of falls in Japanese elderly women because of their inferior physical performance. Low serum 25(OH)D levels appear preventable and easily treated; there is an evident need for greater awareness to screen and thus prevent this condition.

Gait characteristics of elderly people with a history of falls: a dynamic approach

BACKGROUND AND PURPOSE

This study investigated changes in the kinematics of elderly people who experienced at least one fall 6 months prior to data collection. The authors hypothesized that, in order to decrease variability of walking, people with a history of falls would show different kinematic adaptations of their walking patterns compared with elderly people with no history of falls.

SUBJECTS AND METHODS

Twenty-one elderly people who had fallen within the previous 6 months ("fallers"; mean age=72.1 years, SD=4.9) and 27 elderly people with no history of falls ("nonfallers"; mean age=73.8 years, SD=6.4) walked at their preferred stride frequency (STF) as treadmill speed was gradually increased (from 0.18 m/s to 1.52 m/s) and then decreased in steps of 0.2 m/s. Gait parameter measurements were recorded, and statistical analysis was applied using walking speed and STF as independent variables.

RESULTS

Fifty-seven percent of the fallers were unable to walk at the fastest speed, whereas all nonfallers walked comfortably at all walking speeds. Although the fallers showed significantly greater STF, smaller stride lengths, smaller center-of-mass lateral sway, and smaller ankle plantar flexion and hip extension during push-off, they showed increased variability of kinematic measures in their coordination of walking compared with the nonfallers.

DISCUSSION AND CONCLUSION

Although the fallers' adaptations were expected to reduce variability in the coordination of walking, they showed less stable gait patterns (ie, greater variability) compared with the nonfallers. Increased variability of walking patterns may be an important gait risk factor in elderly people with a history of falls.

Foot and leg problems are important determinants of functional status in community dwelling older people

PURPOSE

To determine whether foot and leg problems are independently associated with functional status in a community sample of older people after adjusting for the influence of socio-demographic, physical and medical factors.

METHOD

Data were analysed from the Health Status of Older People project, a population-based study involving a random sample of 1000 community-dwelling people aged 65 - 94 years (533 females, 467 males, mean age 73.4 years +/- 5.87). A structured interview and brief physical examination were used to investigate the associations between self-reported foot and leg problems and functional status. Functional status was assessed using: (i) timed 'Up & Go' test, (ii) self-reported difficulty climbing stairs, (iii) self-reported difficulty walking one kilometer, (iv) self-reported difficulty performing instrumental activities of daily living (IADLs), and (v) self-reported history of one or more falls in the previous 12 months. These associations were then explored after adjusting for socio-demographic, physical and medical factors.

RESULTS

Thirty-six percent of the sample reported having foot or leg problems. Univariate analyses revealed that people with foot and leg problems were significantly more likely to exhibit poorer functional status in all parameters measured. After adjusting for socio-demographic, physical and medical factors, foot and leg problems remained significantly associated with impaired timed 'Up & Go' performance (OR = 2.15, 95%CI 1.55 - 2.97), difficulty climbing stairs (OR = 3.33, 95%CI 1.98 - 5.61), difficulty walking one kilometer (OR = 3.13, 95%CI 2.09 - 4.69), and history of falling (OR = 1.73, 95%CI 1.26 - 2.37).

CONCLUSIONS

Foot and leg problems are reported by one in three community-dwelling people aged 65 years and older. Independent of the influence of age, gender, common medical conditions and other socio-demographic factors, foot and leg problems have a significant impact on the ability to perform functional tasks integral to independent living.

Incidence of loss of ability to walk 400 meters in a functionally limited older population

OBJECTIVES

To assess the incidence of and factors related to nondisabled but functionally limited older adults aged 75 to 85 years losing the ability to walk 400 m.

DESIGN

Observational study with average follow-up of 21 months.

SETTING

Community.

PARTICIPANTS

At baseline, 101 persons with objective signs of functional limitations and intact cognitive function agreed to participate in the study. Of these, 81 were able to walk 400 m at baseline, and 62 participated in the follow-up examination.

MEASUREMENTS

Mobility disability was defined as an inability to complete a 400-m walk test. At baseline, eligible participants (n=81) had the ability to walk 400 m, scored between 4 and 9 on the Short Physical Performance Battery (SPPB; range 0-12), and scored 18 or more on the Mini-Mental State Examination. Demographics, difficulty in daily activities, disease status, behavioral risk factors, and muscle strength were assessed at baseline and follow-up.

RESULTS

Of 62 persons at follow-up, 21 (33.9%) developed incident mobility disability. The strongest predictors of loss of mobility were the time to complete the 400-m walk at baseline (odds ratio (OR)=1.6 per 1-minute difference, 95% confidence interval (CI)=1.04-2.45), and decline in SPPB score over the follow-up (OR=1.4 per 1-point difference, 95% CI=1.01-1.92).

CONCLUSION

Older persons with functional limitations have a high rate of loss of ability to walk 400 m. The 400-m walk test is a highly relevant, discrete outcome that is an ideal target for testing preventive interventions in vulnerable older populations.

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.

Discriminating age and disability effects in locomotion: neuromuscular adaptations in musculoskeletal pathology

We identified biomechanical variables indicative of lower extremity dysfunction, distinct from age-related gait adaptations, and examined interrelationships among these variables to better understand the neuromuscular adaptations in gait. Sagittal plane ankle, knee, and hip peak angles, moments, and powers and spatiotemporal parameters were acquired during preferred-speed gait in 120 subjects: 45 healthy young, 37 healthy elders, and 38 elders with functional limitations due to lower extremity musculoskeletal pathology, primarily arthritis. Multiple analysis of covariance with discriminate analysis, adjusted for gait speed, was used to identify the variables discriminating groups. Correlation analysis was used to explore interrelationships among these variables within each group. Healthy elders were discriminated (sensitivity 76%, specificity 82%) from young adults via decreased late-stance ankle plantar flexion angle, increased late-stance knee power absorption, and early-stance hip extensor power generation. Disabled elders were discriminated (sensitivity 74%, specificity 73%) from healthy elders via decreased late-stance ankle plantar flexor moment and power generation, increased early-stance ankle dorsiflexor moment, and late-stance hip flexor moment and power absorption. Relationships among variables showed a higher degree of coupling for the disabled elders compared with the healthy groups, suggesting a reduced ability to alter motor strategies. Our data suggest that, beyond age-related changes, elders with lower extremity dysfunction rely excessively on passive action of hip flexors to provide propulsion in late stance and contralateral ankle dorsiflexors to enhance stability. These findings support a growing body of evidence that gait changes with age and disablement have a neuromuscular basis, which may be informative in a motor control framework for physical therapy interventions.

Posture of the trunk in the sagittal plane is associated with gait in community-dwelling elderly population

OBJECTIVES

The purpose of this study was to evaluate whether abnormal posture of the trunk in the sagittal plane would affect gait and functional performance in the elderly.

BACKGROUND

There have been very few reports on whether posture of the trunk is related to gait and functional performance.

METHODS

The study group included 237 participants with a mean age of 80.0 years (range 65-94 years). The posture of the trunk in a standing position of the sagittal plane was classified into five groups. We investigated the relationship between the trunk posture in the sagittal plane and age with gait parameters and functional performance such as timed up & go test and functional reach.

RESULTS

In the elderly subjects of normal posture, there was no difference between those in the 65-79 years age group and those in the 80 years and older age group in terms of any gait parameters. Walking abilities were significantly decreased in the abnormal posture groups. Among the abnormal posture groups, elderly in the lumbar kyphosis group had walking disabilities that did not differ between age groups, whereas gait disturbance in the thoracic kyphosis group showed a positive relation with age.

CONCLUSIONS

Posture of the trunk in the sagittal plane was associated not only with the distance and time parameter of gait, but also with functional performance in the elderly.

Knee pain in people aged 80 years and older is not associated with gait parameter and functional performance

We evaluated the differences in gait and functional performance between two groups of elderly people, one consisting of people between 65 and 79 years of age and the other consisting of people over 80 years of age. We analysed whether knee pain affected gait and looked at the functional performance of the timed 'up and go' (TUG) and functional reach (FR) tests. In 247 community-dwelling people aged 65 years and older, consisting of 90 men and 157 women with a mean age of 80 years (range 65-94 years), 47% had knee pain. Shorter stride, shorter step, slower speed, longer TUG and shorter FR were seen in the group aged 80 years and over compared with the group aged 65-79 years. Knee pain was associated with TUG, especially in the group aged 65-79 years. In the group aged 65-79 years with knee pain, a shorter stride and step length, a longer time required to hold a double stance, a slower walking speed and a longer TUG were shown. However, in the group aged 80 years and over, there was no significant difference between participants with and without knee pain for these parameters.

Why do older adults decide they are having difficulty with a task?

OBJECTIVE

Previous studies have identified risk factors for decline in physical function, but they have not examined specific reasons older adults report difficulty with mobility tasks.

DESIGN

Community-dwelling people ( n = 160) aged 59 yr and older in an observational cohort study were questioned to determine the most common cited reasons for self-reported difficulty in task performance.

RESULTS

Mobility tasks were most often reported to be difficult (66%). The reasons cited for difficulty in low exercise tolerance tasks were task modification by method (33%) and rate (33%). For high exercise tolerance tasks, reasons cited included having to modify the rate of performing the task (20%) or the method (13%). Among those who reported difficulty with low exercise tolerance mobility tasks, >80% reported modification (odds ratio, 46.4 [95% confidence limits: 9.75, 220.51]) and 32% also report frequency change (odds ratio, 5.9 [95% confidence limits: 2.72, 12.85]) as the reason for perceiving difficulty. For those who reported difficulty performing high exercise tolerance-demanding tasks, >90% reported modification (odds ratio, 5.5 [95% confidence limits: 2.05, 14.88]) and 61% also report frequency changes (odds ratio, 3.9 [95% confidence limits: 1.93, 8.04]).

CONCLUSION

The findings suggest that people are able to cite specific reasons for difficulty with mobility task performance, most commonly related to task modification.

Is brisk walking an adequate aerobic training stimulus for cardiac patients?

Walking is the most common aerobic training modality utilized in cardiac rehabilitation programs. However, it remains unclear whether or not brisk walking is of a sufficient intensity to improve aerobic fitness in this population. In this study, we investigated whether men and women with coronary artery disease can achieve an exercise intensity that is sufficient to induce a training effect, ie, a training heart rate (THR), defined as >/= 70% of measured maximal heart rate (HRmax), via brisk walking on a flat surface. One hundred forty-two outpatient volunteers from the William Beaumont Hospital Cardiac Rehabilitation Program (Royal Oak, MI) and the University of Wisconsin-La Crosse Exercise and Health Program (La Crosse, WI) were asked to walk one mile as briskly as possible on measured tracks. Heart rate was monitored throughout the walk via radiotelemetry. The percentage of patients within each gender and phase of rehabilitation who attained a THR were assessed using peak or symptom-limited exercise testing to determine the HRmax. All of the women and 90% of the men achieved a THR, averaging 85 +/- 8% and 79 +/- 10% of HRmax, respectively (mean +/- SD). There was no difference in the percentage of phase II or phase III cardiac rehabilitation program patients who achieved a THR. These findings suggest that brisk walking is of a sufficient intensity to elicit a THR in all but the most highly fit patients with coronary disease. Thus, physicians and allied health professionals can prescribe brisk walking on a flat surface to their cardiac patients with confidence that this intensity will achieve cardiorespiratory and health benefits.

Differential Increases in Average Isokinetic Power by Specific Muscle Groups of Older Women Due to Variations in Training and Testing

BACKGROUND

As a person ages, leg speed and power decrease. These changes are associated with increased falls and reduced gait speed. It has been shown that upper leg training in younger persons results in increased strength and power at the specific speed at which resistance training is applied, although there are only limited data concerning speed-specific training effects on lower leg activity. However, because both upper and lower leg speed and power influence gait and balance, it is important to determine the training speeds that selectively improve these variables in older persons.

METHODS

No studies have examined selective speed-specific changes in performance for the upper and lower leg muscles in older individuals. Therefore, we compared shifts in the power-velocity relationship after high-speed (HS) and low-speed (LS) isokinetic training of knee extensors (KE) and flexors (KF), dorsiflexors (DF), and plantar flexors (PF) in community-dwelling women (ages 61 to 75). Subjects were randomly assigned to a HS training, LS training, or control (C) group. Training occurred three times a week for 12 weeks. HS training occurred at 4.73 rad.s(-1) (knee) and 3.14 rad.s(-1) (ankle); LS training for both joint actions was at 1.05 rad.s(-1).

RESULTS

HS training improved KE power at intermediate (3.14 rad.s(-1); p =.0007) and high (5.24 rad.s(-1); p =.0004) testing speeds. Neither the HS nor LS group showed any change in KF as a result of the training. Both LS and HS training improved DF power at all testing speeds; however, PF power improved only with LS training and only at 1.05 rad.s(-1) (p =.0132) and 3.14 rad.s(-1) (p =.0310).

CONCLUSIONS

Our results suggest that, in older women, lower leg training should occur at lower training speeds than upper leg training. Additionally, attention to differential speed-specific training of knee and ankle actions could improve power production, mobility, balance, and other functional measures in older persons.

Mechanical energy analysis identifies compensatory strategies in disabled elders' gait

Current concepts in disablement emphasize the importance of identifying mobility impairments in aging humans to enable timely intervention and, ultimately, prevent disability. Because mobility impairments are likely to result in compensatory movement strategies, recognizing and understanding those strategies may be critical in designing effective interventions for preventing disability. We sought to determine if mechanical energy methods are useful for identifying and understanding lower extremity compensatory movement strategies due to disabilities. Aleshinski's method was used to compute mechanical energy expenditure (MEE) and mechanical energy compensation (MEC) for the sagittal plane stance leg and low-back joints of healthy elders (HE) and disabled elders (DE) during preferred speed and paced (120 steps min(-1)) gait. DE subjects expended less ankle energy in late-stance and more low-back energy in mid-stance than did the HE subjects. When controlling for walking speed, the difference in ankle MEE disappeared, but mid-stance hip MEE was significantly higher for the DE subjects. Despite increased hip and low-back MEE, the DE subjects compensated hip and low-back muscles greater then HE subjects by increasing energy transferred into the pelvis, particularly when walking faster than their self-selected speed. Increased energy transfers into the pelvis during mid-stance may be a strategy used to assist in advancing and controlling the contralateral limb's swing phase. Increased trunk energy, however, may compromise dynamic stability and increase the risk of falling. We conclude that mechanical energy methods are useful for identifying and understanding compensatory movement strategies in elders with disabilities.

Exercise training for rehabilitation and secondary prevention of falls in geriatric patients with a history of injurious falls

OBJECTIVE

To determine the safety and efficacy of an exercise protocol designed to improve strength, mobility, and balance and to reduce subsequent falls in geriatric patients with a history of injurious falls.

DESIGN

A randomized controlled 3-month intervention trial, with an additional 3-month follow-up.

SETTING

Out-patient geriatric rehabilitation unit.

PARTICIPANTS

Fifty-seven female geriatric patients (mean age 82 +/- 4.8 years; range 75-90) admitted to acute care or inpatient rehabilitation with a history of recurrent or injurious falls including patients with acute fall-related fracture.

INTERVENTION

Ambulatory training of strength, functional performance, and balance 3 times per week for 3 months. Patients of the control group attended a placebo group 3 times a week for 3 months. Both groups received an identical physiotherapeutic treatment 2 times a week, in which strengthening and balance training were excluded.

MEASUREMENTS

Strength, functional ability, motor function, psychological parameters, and fall rates were assessed by standardized protocols at the beginning (T1) and the end (T2) of intervention. Patients were followed up for 3 months after the intervention (T3).

RESULTS

No training-related medical problems occurred in the study group. Forty-five patients (79%) completed all assessments after the intervention and follow-up period. Adherence was excellent in both groups (intervention 85.4 +/- 27.8% vs control 84.2 +/- 29.3%). The patients in the intervention group increased strength, functional motor performance, and balance significantly. Fall-related behavioral and emotional restrictions were reduced significantly. Improvements persisted during the 3-month follow-up with only moderate losses. For patients of the control group, no change in strength, functional performance, or emotional status could be documented during intervention and follow-up. Fall incidence was reduced nonsignificantly by 25% in the intervention group compared with the control group (RR:0.753 CI:0.455-1.245).

CONCLUSIONS

Progressive resistance training and progressive functional training are safe and effective methods of increasing strength and functional performance and reducing fall-related behavioral and emotional restrictions during ambulant rehabilitation in frail, high-risk geriatric patients with a history of injurious falls.

Report of having slowed down: evidence for the validity of a new way to inquire about mild disability in elders

BACKGROUND

Mild disability in elderly persons may be detected by eliciting reports of modified task performance, even in the absence of reported difficulty. This study provides evidence for the validity of one type of task modification. namely, slowing, as a measure of mild walking disability.

METHODS

Community-dwelling elders (N = 287) were questioned about whether they were walking indoors as quickly as they had 1 year before and 10 years before. Construct validity was assessed by the degree to which responses to these two questions were logically consistent with a general decline in walking speed, and by determining whether reported slowing was associated with concurrent reports of difficulty walking and with measured gait speed. Predictive validity in subjects without reported difficulty walking was gauged by the association of reported slowing with adverse walking outcomes at 1-year follow-up.

RESULTS

Reports of slowing over 10- and 1-year periods were almost uniformly consistent with a general decline in speed. Reported slowing was significantly associated with reported difficulty walking and with slower gait speed. In the subgroup of elders initially reporting no difficulty walking, reported slowing significantly predicted incident difficulty walking at follow-up, as well as other adverse walking outcomes. For example, among elders who reported slowing, 7%, 10%, and 19% developed new difficulty walking indoors, new difficulty walking outdoors, or stopped walking for pleasure, compared with 0%, 0%, and 3% for those who had not reported slowing (p < .05).

CONCLUSIONS

This study provides evidence for the construct and predictive validity of one type of task modification, namely, slowing in indoor walking. This work contributes to the development of new methods for measuring mild disability, which may in turn form the basis for clinical interventions based on the early identification of functional problems.

The swing phase of human walking is not a passive movement

Many studies have assumed that the swing phase of human walking at preferred velocity is largely passive and thus highly analogous to the swing of an unforced pendulum. In other words, while swing-phase joint moments are generally nonzero during swing, it was assumed that they were either zero or at least negligibly small compared to gravity. While neglect of joint moments does not invalidate a study by default, it remains that the limitations of such an assumption have not been explored thoroughly. This paper makes five arguments that the swing phase cannot be passive, using both original data and the literature: (1) Computer simulations of the swing phase require muscular control to be accurate. (2) Swing-phase joint moments, while smaller than those during stance, are still greater than those due to gravity. (3) Gravity accounts for a minority of the total kinetics of a swing phase. (4) The kinetics due to gravity do not have the pattern needed to develop a normal swing phase. (5) There is no correlation between pendular swing times and human walking periods in overground walking. The conclusion of this paper is that the swing phase must be an actively controlled process, and should be assumed to be passive only when a study does not require a quantitative result. This conclusion has significant implications for many areas of gait research, including clinical study, control theory, and mechanical modeling.

Strength, physical activity, and body mass index: relationship to performance-based measures and activities of daily living among older Japanese women in Hawaii

OBJECTIVES

Remaining strong, lean, and physically active may contribute to successful aging, both by maintaining function and by enabling more independent living. The study objective was to investigate this hypothesis among a long-lived population of older Japanese women.

DESIGN

A cross-sectional study.

SETTING

The island of Oahu, Hawaii.

PARTICIPANTS

A total of 705 community-dwelling women (mean age, 74; range, 55-93).

MEASUREMENTS

As outcomes, 7 physical performance measures including walking speed, the Get Up and Go test, chair stands, functional reach, and hand and foot reaction times, and 8 questions regarding activities of daily living (ADL). As possible predictors, physical activity, body mass index, and quadriceps, grip, and triceps strength.

RESULTS

In multivariable models, one or more of the strength tests was associated positively with six of the seven performance-based measures. Among the significant associations, 1-SD increases in strength were associated with 2 to 4% increases in performance compared with the sample mean. Physical activity was independently, and positively associated with the most complex of the tests, the Get Up and Go test. Body mass index (BMI), in contrast to strength and physical activity, was negatively associated with five of the seven performance tests. Among the significant associations, 1-SD increases in BMI were associated with 3 to 8% reductions in performance. In multivariable models strength was also associated positively with seven of the eight ADLs. In the same models, physical activity was positively associated with five and BMI was negatively associated with six of the ADLs.

CONCLUSION

The results suggest that remaining strong, lean, and physically active provided wide-ranging benefits for this population of older Japanese women.

Predictors of decline in manual performance in older adults

OBJECTIVE

To determine factors that predict decline in manual performance using a multivariate model of determinants of functional limitation.

DESIGN

Longitudinal observational study.

SETTINGS

Ambulatory general medicine clinics, residences of homebound individuals, and a continuing care retirement community.

PARTICIPANTS

Subjects were 485 persons more than 60 years of age and included continuing care retirement community (CCRC) residents (n = 215), chronically homebound older persons (n = 65), and ambulatory older adults (n = 205). Mean age at baseline was 78 years.

MEASUREMENT

Independent variables included demographics, physician measures of upper-extremity joint impairment, comorbidities derived from physical examination and chart abstract, self-assessed arthritis pain, depression, and anxiety. The major dependent variable was 2-year decline in timed manual performance below a threshold associated with need for long-term care services.

RESULTS

The proportion of subjects who exceed a Timed Manual Performance Test threshold of 350 seconds increased slowly from baseline through Year 4 for all age groups but rose rapidly from Year 4 to Year 6 for the oldest group (> 85 years at baseline). Using a discrete survival model, we found that age, education, grip strength, and psychological status predicted crossing the manual performance threshold within a 2-year period.

CONCLUSIONS

The findings, coupled with earlier findings that upper extremity joint impairment predicted both grip strength and manual performance, suggest that joint impairment may be an important risk factor for future functional limitation. Since diminished hand function has been shown to predict dependency, development and testing of interventions to maintain or restore upper extremity joint function and reduce pain would appear to be a high research priority.

Predictors of five-year functional ability in a longitudinal survey of men and women aged 75 to 80. The 1914-population in Glostrup, Denmark

Data from a longitudinal study of aging-a Danish substudy within a Nordic comparative longitudinal Research on Ageing study (NORA)-is presented. The goal is to highlight easily measured factors, that are relevant to prevention and postponement of disability in the elderly. In a population-based, representative sample, the objectives were: to describe five-year outcome regarding death and functional ability to age 75 to 80, as well as individual changes in muscle strength, physical performance in simple function tests and self-reported physical activity, and relate "risk markers" to five-year outcome. Baseline values were obtained in 405 participants in the 1989-survey of the 1914-cohort in Copenhagen County. The 307 survivors were invited for the survey of 80-year olds in 1995. Outcome was measured as death, non-participation, decline, stability or improvement in two measures of mobility function (tiredness and dependency). Between ages 75 and 80, 24% died, 12% did not participate in the follow-up, 23% became tired performing mobility functions, 20% did not change but 21% became less tired; 19% became more dependent, 44% remained stable and only 2% improved in relation to dependency on help in mobility functions. "Stability" in mobility functions was related to ability to mount stairs, walking speed, mood and physical activity. Number of chronic diseases and low pulmonary function were only related to mobility in men. Among people who improved their function, many had rather low baseline-values, suggesting regression to the mean. Multiple logistic regression was conducted. The follow-up survey found that female participants were more physically active at baseline than non-participants. Five-year mortality was independently related to physical activity (RR = 0.41), pulmonary function in men (RR = 0.45/l increase) and muscle strength in women (RR = 0.65/N/kg increase). Dependency at follow-up in men was related to low physical activity at baseline (RR = 4.14), disability to mount a 50-cm step (RR = 4.07), two or more chronic diseases (RR = 3.36) and, only marginally significant, knee extension strength. In women only low physical activity was predictive (RR = 4.32). From baseline to follow-up, 34% of the population had reduced their physical activities. Knee extension strength was reduced from 6.0 to 4.4 N/kg in men, and from 4.2 to 3.3 N/kg in women. In the stair-mounting test, 44% could only attain one or more 10 cm steps lower than at baseline. A dose-response-relationship of declining muscle mass to functional limitations was observed in men and women at the age of 75 as well as the age of 80.