Jonathan F. Bean

The Relationship Between Leg Power and Physical Performance in Mobility‐Limited Older People

The purpose of this study was to assess the influence of leg power and leg strength on the physical performance of community‐dwelling mobility‐limited older people.

Aging, muscle activity, and balance control : physiologic changes associated with balance impairment.

Older adults demonstrate increased amounts of postural sway, which may ultimately lead to falls. The mechanisms contributing to age-related increases in postural sway and falls in the elderly remain unclear. In an effort to understand age-related changes in posture control, we assessed foot center-of-pressure (COP) displacements and electromyographic data from the tibialis anterior, soleus, vastus lateralis, and biceps femoris collected simultaneously during quiet-standing trials from elderly fallers, elderly non-fallers, and healthy young subjects. Both traditional measures of COP displacements and stabilogram-diffusion analysis were used to characterize the postural sway of each group. Regression analyses were used to assess the relationship between the COP measures and muscle activity. Elderly fallers demonstrated significantly greater amounts of sway in the anteroposterior (AP) direction and greater muscle activity during quiet standing compared with the young subjects, while elderly non-fallers demonstrated significantly greater muscle activation and co-activation compared with the young subjects. No significant differences were found between elderly fallers and elderly non-fallers in measures of postural sway or muscle activity. However, greater postural sway in both the AP and mediolateral (ML) directions and trends of greater muscle activity were found in those older adults who demonstrated lower scores on clinical measures of balance. In addition, short-term postural sway was found to be significantly correlated with muscle activity in each of these groups. This work suggests that high levels of muscle activity are a characteristic of age-related declines in postural stability and that such activity is correlated with short-term postural sway. It is unclear whether increases in muscle activity preclude greater postural instability or if increased muscle activity is a compensatory response to increases in postural sway.

High-velocity resistance training increases skeletal muscle peak power in older women.

OBJECTIVES: Peak power declines more precipitously than strength with advancing age and is a reliable measure of impairment and a strong predictor of functional performance. We tested the hypothesis that a high‐velocity resistance‐training program (HI) would increase muscle power more than a traditional low‐velocity resistance‐training program (LO).

Chronic Musculoskeletal Pain and the Occurrence of Falls in an Older Population

CONTEXT Chronic pain is a major contributor to disability in older adults; however, the potential role of chronic pain as a risk factor for falls is poorly understood. OBJECTIVE To determine whether chronic musculoskeletal pain is associated with an increased occurrence of falls in a cohort of community-living older adults. DESIGN, SETTING, AND PARTICIPANTS The Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly (MOBILIZE) Boston Study is a population-based longitudinal study of falls involving 749 adults aged 70 years and older. Participants were enrolled from September 2005 through January 2008. MAIN OUTCOME MEASURE Participants recorded falls on monthly calendar postcards mailed to the study center during an 18-month period. RESULTS There were 1029 falls reported during the follow-up. A report of 2 or more locations of musculoskeletal pain at baseline was associated with greater occurrence of falls. The age-adjusted rates of falls per person-year were 1.18 (95% confidence interval [CI], 1.13-1.23) for the 300 participants with 2 or more sites of joint pain, 0.90 (95% CI, 0.87-0.92) for the 181 participants with single-site pain, and 0.78 (95% CI, 0.74-0.81) for the 267 participants with no joint pain. Similarly, more severe or disabling pain at baseline was associated with higher fall rates (P < .05). The association persisted after adjusting for multiple confounders and fall risk factors. The greatest risk for falls was observed in persons who had 2 or more pain sites (adjusted rate ratio [RR], 1.53; 95% CI, 1.17-1.99), and those in the highest tertiles of pain severity (adjusted RR, 1.53; 95% CI, 1.12-2.08) and pain interference with activities (adjusted RR, 1.53; 95%CI, 1.15-2.05), compared with their peers with no pain or those in the lowest tertiles of pain scores. CONCLUSIONS Chronic pain measured according to number of locations, severity, or pain interference with daily activities was associated with greater risk of falls in older adults.

High intensity strength training improves strength and functional performance after stroke.

OBJECTIVE To evaluate the effects of a progressive resistance strength training program on changes in muscle strength, gait, and balance in older individuals 1 yr after stroke, seven individuals were recruited who were greater than 60-yr-old, 1 yr after stroke, living at home, and able to follow verbal commands. DESIGN Subjects participated in a 12-wk 2x per wk resistance training program at 70% of 1 repetition maximum. RESULTS Lower limb strength improved 68% on the affected side and 48% on the intact side during training, with the largest increases observed for hip extension (affected side: 88%, P < 0.01; intact side: 103%, P < 0.001). Repeated chair stand time decreased 21% (P < 0.02). Motor performance assessed by the Motor Assessment Scale improved 9% (P < 0.04) and static and dynamic balance (Berg balance scale) improved 12% (P < 0.004). Progressive resistance training in individuals 1 yr after stroke improves affected and intact side lower limb strength and was associated with gains in chair stand time, balance, and motor performance. CONCLUSIONS These results support the concept that strength training is an appropriate intervention to improve the quality of physical function in older community dwelling stroke survivors.

High-Intensity Resistance Training Improves Muscle Strength, Self-Reported Function, and Disability in Long-Term Stroke Survivors

Background and Purpose— To evaluate the efficacy of supervised high-intensity progressive resistance training (PRT) on lower extremity strength, function, and disability in older, long-term stroke survivors. Methods— Forty-two volunteers aged 50 years and above, 6 months to 6 years after a single mild to moderate stroke, were randomized into either a control group of upper extremity stretching or a PRT group that received a 12-week supervised high-intensity resistance training program consisting of bilateral leg press (LP), unilateral paretic and nonparetic knee extension (KE), ankle dorsiflexion (DF), and plantarflexion (PF) exercises. Functional performance was assessed using the 6-minute walk, stair-climb time, repeated chair-rise time, and habitual and maximal gait velocities. Self-reported changes in function and disability were evaluated using the Late Life Function and Disability Instrument (LLFDI). Results— Single-repetition maximum strength significantly improved in the PRT group for LP (16.2%), paretic KE (31.4%), and nonparetic KE (38.2%) with no change in the control group. Paretic ankle DF (66.7% versus −24.0%), paretic ankle PF (35.5% versus −20.3%), and nonparetic ankle PF (14.7% versus −13.8%) significantly improved in the PRT group compared with the control. The PRT group showed significant improvement in self-reported function and disability with no change in the control. There was no significant difference between groups for any performance-based measure of function. Conclusions— High-intensity PRT improves both paretic and nonparetic lower extremity strength after stroke, and results in reductions in functional limitations and disability.

Muscle Power of the Ankle Flexors Predicts Functional Performance in Community-Dwelling Older Women

OBJECTIVES: To test the hypothesis that peak power of the ankle flexors is related to physical functioning in older women with functional limitations.

Musculoskeletal pain and risk for falls in older disabled women living in the community.

To determine whether musculoskeletal pain increased risk for falls in older women with disabilities.

Increased Velocity Exercise Specific to Task (InVEST) Training: A Pilot Study Exploring Effects on Leg Power, Balance, and Mobility in Community‐Dwelling Older Women

Objectives: To evaluate a dynamic form of weighted vest exercise suitable for home use and designed to enhance muscle power, balance, and mobility.

Weighted Stair Climbing in Mobility-Limited Older People: A Pilot Study

OBJECTIVES: To evaluate weighted stair climbing exercise (SCE) as a means of increasing lower extremity muscle power in mobility‐limited older people.