Increased trunk extension endurance is associated with meaningful improvement in balance among older adults with mobility problems

Suri P, Kiely DK, Leveille SG, Frontera WR, Bean JF. Increased trunk extension endurance is associated with meaningful improvement in balance among older adults with mobility problems.

Objective

To determine whether trunk extension endurance changes with training are associated with clinically meaningful improvements in balance among mobility-limited older adults.

Design

Longitudinal data from a randomized controlled trial.

Setting

Outpatient rehabilitation research center.

Participants

Community-dwelling older adults (N=64; mean age, 75.9y) with mobility limitations as defined by a score of 4 to 10 on the Short Physical Performance Battery.

Interventions

Sixteen weeks of progressive resistance training.

Main Outcome Measures

Outcomes were the Berg Balance Scale (BBS) and the Unipedal Stance Time (UST). Predictors included leg strength, leg power, trunk extension endurance, and the product of heart rate and blood pressure (RPP) at the final stage of an exercise tolerance test. We performed an analysis of data from participants who completed 16 weeks of training by using binary outcomes defined by a clinically meaningful change (CMC) from baseline to completion of the intervention (BBS=4 units; UST=5s). The association of predictor variables with balance outcomes was examined separately and together in multivariate adjusted logistic regression models.

Results

Trunk extension endurance in seconds (1.04 [1.00–1.09]) was independently associated with CMC on the BBS. Trunk extension endurance (1.02 [1.00–1.03]) was independently associated with CMC on the UST. Other physical attributes were not associated with meaningful change in balance.

Conclusions

Improvements in trunk extension endurance were independently associated with CMCs in balance in older adults. Leg strength, leg power, and RPP were not associated with CMC in balance. Poor trunk extension endurance may be a rehabilitative impairment worthy of further study as a modifiable factor linked to balance among older adults.     

Construct and predictive validity of a self-reported measure of preclinical mobility limitation

OBJECTIVES: To validate self-reported preclinical mobility limitation concept and self-report assessment method against muscle power and walking speed, and to study the predictive validity of preclinical mobility limitation with respect to future risk of manifest mobility limitation. DESIGN: Observational prospective cohort study and cross-sectional analysis. SETTING: Research laboratory and community. PARTICIPANTS: A total of 632 community-living (age range, 75-81 y) women and men took part in the baseline assessments and 302 persons in the semi-annual interviews on mobility limitation over 2 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Walking speed, muscle power, and self-reported preclinical and manifest mobility limitation. Preclinical mobility limitation was defined as self-reported tiredness or modification of task performance without task difficulty. At baseline, 4 subgroups were created according to self-reported preclinical mobility limitation in any of 3 mobility tasks (walking 2 km, walking 0.5 km, climbing up stairs): no limitation, preclinical limitation, and minor and major manifest limitation. RESULTS: At baseline, participants with preclinical mobility limitation showed intermediate levels of walking speed and muscle power, compared with those with no limitation or manifest mobility limitation. Participants reporting baseline preclinical mobility limitation had 3- to 6-fold higher age- and sex-adjusted risk of progressing to major manifest mobility limitation during the 2-year follow-up compared with participants with no limitation at baseline, whereas the risk among those with minor limitation at baseline was 14- to 18-fold higher compared with those with no limitation. CONCLUSIONS: The self-report assessment tool proved to be a valid measure to capture the early signs of disability and may serve as an inexpensive tool for identifying those nondisabled persons at high risk for future disability.     

Lower extremity physical performance, self-reported mobility difficulty, and use of compensatory strategies for mobility by elderly women

Ganesh SP, Fried LP, Taylor DH Jr, Pieper CF, Hoenig HM. Lower extremity physical performance, self-reported mobility difficulty, and use of compensatory strategies for mobility by elderly women.

Objective

To describe the relationship between lower extremity physical performance, self-reported mobility difficulty, and self-reported use of compensatory strategies (CSs) for mobility inside the home.

Design

Cross-sectional exploratory study.

Setting

Community-dwelling elders.

Participants

Disabled, cognitively intact women 65 years or older (N=1002), from the Women's Health and Aging Study I.

Interventions

Not applicable.

Main Outcome Measures

CS scale: no CS, behavioral modifications (BMs) only, durable medical equipment (DME) with or without use of BMs, and any use of human help (HH); and 3 dichotomous CS measures: any CS (vs none); DME+HH (vs BMs only, among users of any CS); any HH (vs DME only, among users of any DME/HH).

Results

Self-reported mobility difficulty and physical performance were significantly correlated with one another (r=−.57, P<.0001) and with the CS scale ([r=.51, P<.001] and [r=−.54, P<.0001], respectively). Sequential logistic regressions showed self-reported difficulty and physical performance were significant independent predictors of each category of CS. For the any CS and DME+HH models, the odds ratio for self-reported difficulty decreased by approximately 50% when physical performance was included in the model, compared with difficulty alone ([18.0 to 8.6] and [7.3 to 3.8], respectively), but both physical performance and difficulty remained significant predictors (P<.0001). The effects of covariates differed for the various CS categories, with some covariates having independent relationships to CS, and others appearing to have moderating or mediating effects on the relationship of self-reported difficulty or physical performance to CS.

Conclusions

Physical performance, self-reported difficulty, health conditions, and contextual factors have complex effects on the way elders carry out mobility inside the home.     

Compensatory strategies used by older adults facing mobility disability

Preclinical disability in mobility tasks can be recognized by asking people without overt mobility disability whether they have changed the way, either the manner or the frequency, of doing a mobility task because of a health or physical condition. Like other compensatory strategies, preclinical mobility disability has a dual nature as both a risk marker associated with impairment or limitation and a mediating factor affecting the natural history of disability. The method of ascertaining preclinical disability through self-report has been shown to have construct validity, to be reliable, and to identify people at an elevated risk of developing overt mobility disability over 1 to 2 years. Many worthy research questions in this field remain to be addressed, especially regarding qualitative heterogeneity (doing more vs doing less) and interactions among compensatory strategies. Nonetheless, there is sufficient evidence to apply what is known about preclinical disability to screening in clinical settings. This area of research and practice constitutes an opportunity for physical medicine and rehabilitation and geriatric medicine to jointly make a large beneficial impact on population health through strategies to prevent disability because rapidly growing numbers of older adults will experience this early and potentially malleable stage.     

Improvement of Stance Control and Muscle Performance Induced by Focal Muscle Vibration in Young-Elderly Women: A Randomized Controlled Trial

Filippi GM, Brunetti O, Botti FM, Panichi R, Roscini M, Camerota F, Cesari M, Pettorossi VE. Improvement of stance control and muscle performance induced by focal muscle vibration in young-elderly women: a randomized controlled trial.

Objective

To determine the effect of a particular protocol of mechanical vibration, applied focally and repeatedly (repeated muscle vibration [rMV]) on the quadriceps muscles, on stance and lower-extremity muscle power of young-elderly women.

Design

Double-blind randomized controlled trial; 3-month follow-up after intervention.

Setting

Human Physiology Laboratories, University of Perugia, Italy.

Participants

Sedentary women volunteers (N=60), randomized in 3 groups (mean age ± SD, 65.3±4.2y; range, 60–72).

Intervention

rMV (100Hz, 300–500μm, in three 10-minute sessions a day for 3 consecutive days) was applied to voluntary contracted quadriceps (vibrated and contracted group) and relaxed quadriceps (vibrated and relaxed group). A third group received placebo stimulation (nonvibrated group).

Main Outcome Measures

Area of sway of the center of pressure, vertical jump height, and leg power.

Results

Twenty-four hours after the end of the complete series of applications, the area of sway of the center of pressure decreased significantly by approximately 20%, vertical jump increased by approximately 55%, and leg power increased by approximately 35%. These effects were maintained for at least 90 days after treatment.

Conclusions

rMV is a short-lasting and noninvasive protocol that can significantly and persistently improve muscle performance in sedentary young-elderly women.     

Clinimetric properties of the de Morton Mobility Index in healthy, community-dwelling older adults

Davenport SJ, de Morton NA. Clinimetric properties of the de Morton Mobility Index in healthy, community-dwelling older adults.

Objective

To investigate the clinimetric properties of the de Morton Mobility Index (DEMMI) in healthy, community-dwelling older adults.

Design

Cohort study.

Setting

Retirement village and Returned and Services League (RSL) club in Melbourne, Australia.

Participants

All participants were 65 years or older, healthy, and living within the community. The validation study included participants recruited from a retirement village (n=61), and the reliability studies included participants recruited from an RSL club and a subset of participants from the retirement village.

Interventions

Not applicable.

Main Outcome Measures

Mobility was assessed using the DEMMI. The percentage of participants who scored the highest and lowest possible score on the DEMMI was calculated to determine whether a floor or ceiling effect occurred. The minimal clinically important difference (MCID) was estimated using a distribution-based method. Reliability was assessed independently and concurrently using the minimal detectable change at 90% confidence (MDC₉₀).

Results

Evidence of convergent and discriminant validity was obtained for the DEMMI by examining correlations with measures of related constructs, the Lower Extremity Functional Scale (r=.69) and Quality of Life Scale scores (r=.28), respectively. Participants who ambulated without a gait aid (82.62±10.63) had significantly higher (P<.0) DEMMI scores than those who ambulated with an aid (64.1±12.40), providing evidence of known groups validity. No floor or ceiling effect was identified. The MCID was 7 points. The MDC₉₀ was 13 (95% CI, 8.76–17.05) points on the 100-point scale.

Conclusion

DEMMI scores in healthy, community-dwelling older adults are both valid and reliable.     

Leg preference associated with protective stepping responses in older adults

Background

Asymmetries in dynamic balance stability have been previously observed. The goal of this study was to determine whether leg preference influenced the stepping response to a waist-pull perturbation in older adult fallers and non-fallers.

Methods

39 healthy, community-dwelling, older adult (> 65 years) volunteers participated. Participants were grouped into non-faller and faller cohorts based on fall history in the 12 months prior to the study. Participants received 60 lateral waist-pull perturbations of varying magnitude towards their preferred and non-preferred sides during quiet standing. Outcome measures included balance tolerance limit, number of recovery steps taken and type of recovery step taken for perturbations to each side.

Findings

No significant differences in balance tolerance limit (P ≥ 0.102) or number of recovery steps taken (η²_partial ≤ 0.027; P ≥ 0.442) were observed between perturbations towards the preferred and non-preferred legs. However, non-faller participants more frequently responded with a medial step when pulled towards their non-preferred side and cross-over steps when pulled towards their preferred side (P = 0.015).

Interpretation

Leg preference may influence the protective stepping response to standing balance perturbations in older adults at risk for falls, particularly with the type of recovery responses used. Such asymmetries in balance stability recovery may represent a contributing factor for falls among older individuals and should be considered for rehabilitation interventions aimed at improving balance stability and reducing fall risk.     

High-frequency vibration training increases muscle power in postmenopausal women

OBJECTIVE: To test whether training on a high-frequency (28Hz) vibrating platform improves muscle power and bone characteristics in postmenopausal women. DESIGN: Randomized controlled trial with 6-month follow-up. SETTING: Outpatient clinic in a general hospital in Italy. PARTICIPANTS: Twenty-nine postmenopausal women (intervention group, n=14; matched controls, n=15). INTERVENTION: Participants stood on a ground-based oscillating platform for three 2-minute sessions for a total of 6 minutes per training session, twice weekly for 6 months. The controls did not receive any training. Both groups were evaluated at baseline and after 6 months. MAIN OUTCOME MEASURES: Muscle power, calculated from ground reaction forces produced by landing after jumping as high as possible on a forceplate, cortical bone density, and biomarkers of bone turnover. RESULTS: Over 6 months, muscle power improved by about 5% in women who received the intervention, and it remained unchanged in controls (P=.004). Muscle force remained stable in both the intervention and control groups. No significant changes were observed in bone characteristics. CONCLUSION: Reflex muscular contractions induced by vibration training improve muscle power in postmenopausal women.     

Effects of reducing resistance, repetitions, and frequency of back-strengthening exercise in healthy young women: a pilot study

OBJECTIVE: To determine the effects of reducing intensity or frequency of back-strengthening exercise on back extensor strength. DESIGN: Randomized controlled trial. SETTING: Exercises were performed in participants' homes. Instruction and measurements were performed at the rehabilitation center in the hospital. PARTICIPANTS: Fifty-eight healthy female volunteers (mean age, 20 y). INTERVENTIONS: Participants were assigned to 1 of 5 exercise intervention groups: control; standard protocol (STD) that has been shown to increase back extensor strength; weight reduction (WRD); repetition reduction (RRD); and frequency reduction (FRD). Back exercises involved lifting a weighted backpack while in a prone position. The study period was 12 weeks. MAIN OUTCOME MEASURE: Isometric back extensor strength. RESULTS: Back extensor strength increased significantly in all groups except the control group. The maximum increase was achieved by the STD group (39%), followed by the FRD (25%), WRD (22%), RRD (20%), and control (5%) groups. Percentage change in back extensor strength was significantly greater in the STD group than in all other groups except the FRD group. CONCLUSIONS: Back extensor strength in the WRD, RRD, and FRD groups was significantly higher at 12 weeks compared with baseline. Reductions in intensity and frequency resulted in similar effects on increases in back extensor strength.     

Self-reported difficulty in climbing up or down stairs in nondisabled elderly

Verghese J, Wang C, Xue X, Holtzer R. Self-reported difficulty in climbing up or down stairs in nondisabled elderly.

Objective

To examine clinical and functional correlates of self-reported difficulty in climbing up or climbing down stairs in older adults.

Design

Cross-sectional survey.

Setting

Community sample.

Participants

Older adults (N=310; mean age, 79.7y; 62% women), without disability or dementia.

Interventions

Not applicable.

Main Outcome Measures

Clinical and functional status as well as activity limitations (able to perform activities of daily living [ADLs] with some difficulty).

Results

Of the 310 subjects, 140 reported difficulties in climbing up and 83 in climbing down stairs (59 both). Self-reported difficulty in climbing up stairs was associated with hypertension, arthritis, and depressive symptoms. Difficulty in climbing up stairs was also associated with poor balance and grip strength as well as neurologic gait abnormalities. Subjects with difficulty climbing down stairs had more falls. Both activities were associated with leg claudication, fear of falling, non-neurologic gait abnormalities, and slow gait. Examined individually, self-reported difficulty climbing down stairs captured a wider spectrum of ADL limitations than climbing up stairs. However, combined difficulty in both phases of stair climbing had a stronger association with activity limitations (vs no difficulty; odds ratio, 6.58; 95% confidence interval, 3.35−12.91) than difficulty in any one phase alone.

Conclusions

Self-reported difficulty in climbing up and down stairs revealed commonalities as well as differences in related clinical correlates. Difficulty in both climbing up and down stairs should be separately assessed to better capture clinical and functional status in older adults.     

Using Timed Up and Go and Usual Gait Speed to Predict Incident Disability in Daily Activities Among Community-Dwelling Adults Aged 65 and Older

Objectives

To compare the ability of Timed Up and Go (TUG) and usual gait speed (UGS) to predict incident disability completing basic activities of daily living (ADL) and instrumental ADL (IADL) in older adults free of disability at baseline, and to provide estimates for the probability of incident disability at different levels of baseline mobility performance.

Design

Data from the first 2 waves of The Irish Longitudinal Study on Ageing, a study assessing health, economic, and social aspects of ageing in adults aged ≥50 years.

Setting

A nationally representative, population-based sample of community-dwelling adults.

Participants

Participants aged ≥65 years who completed mobility tests during a health assessment, had no reported difficulty in ADL/IADL, and had a Mini-Mental State Examination score ≥24 were re-interviewed after 2 years (n=1664).

Interventions

Not applicable.

Main Outcome Measures

Participants completed the TUG and UGS at baseline and indicated difficulty in a number of basic ADL and IADL at follow-up.

Results

Receiver operating characteristic analysis indicated that TUG and UGS are acceptable tools to predict disability in ADL and IADL (area under the curve [AUC]=.65–.75) with no significant difference between them (P>.05). Both were excellent predictors of difficulty in higher-level functioning tasks such as preparing hot meals, taking medications, and managing money (AUC>.80). Predictive probabilities were obtained across a range of performance levels.

Conclusions

TUG and UGS have similar predictive ability in relation to incident disability in basic ADL and IADL. Predictive probabilities can be used to identify those most at risk and in need of particular services. Since improving physical function can prevent or delay dependence in ADL/IADL, TUG and UGS can also provide performance goals and feedback during exercise interventions.     

Promoting physical activity among women with mobility impairments: a randomized controlled trial to assess a home- and community-based intervention

OBJECTIVE: To assess the effectiveness of an intervention to promote physical activity and fitness in physically disabled women. DESIGN: Randomized controlled trial. SETTING: Home or community. PARTICIPANTS: Seventy-five adult women with mobility limitations. INTERVENTION: Incorporated behavioral techniques, social support, and education to promote exercise. MAIN OUTCOME MEASURES: Fitness measures included weight, body mass index, resting blood pressure and heart rate, time to complete a mobility course, and heart rate during and blood pressure after navigating the course. Also collected self-reported experience of secondary conditions and weekly self-reports of physical activity. RESULTS: We found no significant fitness differences between groups, except for peak heart rate. However, paired t tests of the physical activity data revealed the experimental group significantly increased its total weekly physical activity minutes (P=.04), and the increase in weekly cardiovascular activity approached significance (P=.06). CONCLUSIONS: The experimental group did not experience better fitness or fewer secondary conditions than the controls. However, the experimental group's physical activity data indicate that this group significantly increased its activity over 6 months. Thus, although this study did not detect health changes, it showed that mobility-impaired women can adopt and maintain a physical activity program.     

Prevalence and etiology of delayed orthostatic hypotension in adult women

Madhavan G, Goddard AA, McLeod KJ. Prevalence and etiology of delayed orthostatic hypotension in adult women.

Objective

To evaluate the contributing roles of venous status, microvascular filtration, and calf muscle pump activity in the etiology of delayed orthostatic hypotension (OH).

Design

Unblinded within-subjects trial.

Setting

Academic clinical research center.

Participants

Convenience sample of healthy adult women (N=30) with an age range of 30 to 65 years.

Intervention

Plantar micromechanical stimulation applied at a 45-Hz frequency and a 50-μm amplitude for a duration of 30 minutes during upright sitting.

Main Outcome Measure

Diastolic blood pressure (DBP).

Results

White women (mean age, 51.8±1.3y) were recruited and screened for delayed OH. About one quarter (9/33) of the screened subjects showed delayed OH as determined by a significant decrease in blood pressure after at least 15 minutes of quiet sitting. Air plethysmographic assessment provided no evidence of venous insufficiency (venous filling index, >2.5mL/s; venous volume, >80mL) or excessive microvascular filtration in the affected subjects, whereas activation of the calf muscle pump (CMP) through plantar-based micromechanical stimulation consistently resulted in a significant increase in systolic blood pressure (SBP) (ΔSBP=22.8±3.9mmHg, P=.003) and DBP (ΔDBP=20.9±3.3mmHg, P=.002).

Conclusions

About 25% of the adult women studied showed delayed OH during quiet sitting and the proximate cause appears to be neuromuscular in origin, specifically inadequate calf muscle tone, because venous and microvascular filtration status is normative in the delayed OH subpopulation and CMP stimulation reverses the hypotension.     

Obesity influences transitional states of disability in older adults with knee pain

Rejeski WJ, Ip EH, Marsh AP, Zhang Q, Miller ME. Obesity influences transitional states of disability in older adults with knee pain.

Objectives

This study employed relatively new statistical methods to understand how many states are needed to describe disability in older adults with knee pain, describe the relative probability of transitioning between states over time, and examine whether obesity influences the probability of transitioning between states.

Design

Prospective epidemiologic study of older adults with knee pain.

Setting

Community.

Participants

The participants, 245 women and 235 men, were 65 years or older, had chronic knee pain on most days, and had difficulty with at least 1 mobility-related activity caused by knee pain.

Interventions

Not applicable.

Main Outcome Measure

The primary instrument, the Pepper Assessment Tool for Disability, evaluated self-reported difficulty with mobility, basic activities of daily living (ADLs), and instrumental activities of daily living (IADLs).

Results

The Hidden Markov Model yielded 6 states reflecting changes in mobility, ADLs, and IADLs. There is evidence that loss in more demanding mobility-related activities such as stair climbing is an early sign for the onset of disability and that functional deficits in the lower extremities are critical to the early loss of ADLs. Overall the trend is for older adults to experience greater progression than regression and for obesity to be important in understanding severe states of disability.

Conclusions

These data provide a strong rationale for characterizing disability on a continuum and underscore the fluid nature of disability in older adults. As expected, lower-extremity function plays a key role in the disablement process; obesity is also particularly relevant to understanding severe states of disability.     

Oxygen consumption during machine-assisted and unassisted walking: a pilot study in hemiplegic and healthy humans

OBJECTIVE: To determine whether a gait-training (GT) machine influenced walking time duration and oxygen consumption in hemiplegic patients. DESIGN: Repeated measures with comparison of 2 groups. SETTING: Physiology laboratories in a rehabilitation hospital. PARTICIPANTS: Seven patients with stroke-related hemiplegia (2 men, 5 women; age, 46+/-11y; time since stroke, 12+/-9wk) and 7 healthy subjects (3 men, 4 women; age, 30+/-7y). INTERVENTIONS: Floor walking (FW) and GT-assisted walking with and without 50% body-weight support (BWS). MAIN OUTCOME MEASURES: Walking time duration, oxygen consumption (Vo(2)), minute ventilation (V(E)), and heart rate. RESULTS: When the condition effect was analyzed independently from the group, mean Vo(2) was higher during FW than during the GT tests (post hoc analysis: FW vs GT, P=.017; FW vs GT+BWS, P<.002). When the groups were compared independently of the condition, the group with hemiplegia had a significantly shorter walking time duration (analysis of variance [ANOVA], P<.001) and a significantly higher Vo(2) as a percentage of baseline (ANOVA, P=.03), compared with the controls. Walking time duration was influenced by walking condition (ANOVA, P<.001; post hoc analysis: FW vs GT, P<.001; FW vs GT+BWS, P<.001). Ve was influenced by walking condition (ANOVA, P=.043; not significant in the post hoc analysis) and was higher in the group with hemiplegia (ANOVA, P=.02). Heart rate was not influenced by walking condition (P=.11). A group effect was found with heart rate in cycles per minute (P=.035) but not as a percentage of baseline. No interaction was found between the ANOVA group-effect factor and the ANOVA walking-condition effect factor. CONCLUSIONS: Compared with FW, GT assistance increased walking time duration and reduced Vo(2) in patients with severe hemiplegia.     

Sensorimotor and psychosocial correlates of adaptive locomotor performance in older adults

Deshpande N, Metter EJ, Ferrucci L. Sensorimotor and psychosocial correlates of adaptive locomotor performance in older adults.

Objective

To identify sensorimotor and psychosocial factors independently associated with an inability to perform adaptive walking tasks in older adults.

Design

Cross-sectional cohort study.

Setting

Population-based older cohort.

Participants

Community-living elderly (N=720; age ≥65y) who could walk 7m at self-selected normal speed.

Interventions

Not applicable.

Main Outcome Measures

Walking performance was assessed in 4 walking tests: fast walking, obstacle crossing, narrow-based walking, and walking while talking. Possible correlates of the inability to perform the walking test included knee extensor strength, lower limb coordination, Cumulative Somatosensory Impairment Index (CSII), visual acuity and contrast sensitivity, cognition, depression, personal mastery, social support, and years of education.

Results

The results of binary logistic regression analyses, adjusted for demographics and self-selected normal speed, demonstrated that poor knee extensor strength was associated with an inability to perform tasks demanding an increase in walking speed (fast walking and obstacle crossing). Both poor lower limb coordination and higher CSII were significantly associated with failure in tests that demanded precise control over foot placement (obstacle crossing and narrow-based walking). Higher CSII was associated with failure in all tests except in the walking while talking. In contrast, poor cognition was associated with an inability to perform walking while talking. Poor personal mastery was the only variable that was associated with failure in all walking tests.

Conclusions

The results demonstrated a systematic and coherent pattern in these associations and indicated possible sensorimotor and psychological parameters that should be specifically investigated and should be intervened if a patient reports a difficulty/inability in walking in certain situations.     

Maintenance of aquatic training-induced benefits on mobility and lower-extremity muscles among persons with unilateral knee replacement

Valtonen A, Pöyhönen T, Sipilä S, Heinonen A. Maintenance of aquatic training-induced benefits on mobility and lower-extremity muscles among persons with unilateral knee replacement.

Objective

To evaluate the maintenance of observed aquatic training-induced benefits at 12-month follow-up.

Design

Twelve-month follow-up of a randomized controlled study.

Setting

Research laboratory and hospital rehabilitation pool.

Participants

Population-based sample of 55 to 75-year-old women and men 4 to 18 months (on average 10mo) after unilateral knee replacement. Fifty people were willing to participate in the exercise trial and 42 people in the follow-up study.

Intervention

Twelve-month follow-up of 12-week progressive aquatic resistance training, or no intervention.

Main Outcome Measures

Isokinetic knee extensor and flexor power, thigh muscle cross-sectional area (CSA), habitual walking speed, stair ascending time, and sit-to-stand test.

Results

After a 12-month follow-up, a 32% (95% confidence interval [CI], 10–53) training effect in knee extensor power (P=.008) and 50% (95% CI, 9–90) in knee flexor power (P=.005) of the operated knee remained. In muscle CSA, the training-induced benefit had disappeared at the follow-up. All the significant 12-week improvements in habitual walking speed, stair ascending time, and sit-to-stand in the training group compared with controls were lost at follow-up.

Conclusions

After the 12-month follow-up, the 12-week aquatic training-induced benefits in knee extensor and flexor power were maintained, whereas the mobility benefits had disappeared. Aquatic resistance training should be continued at least on some level to maintain the training-induced benefits in mobility.