Publications (5)14.99 Total impact
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Article: Validity of an exercise test based on habitual gait speed in mobility-limited older adults.
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ABSTRACT: To evaluate whether a customized exercise tolerance testing (ETT) protocol based on an individual's habitual gait speed (HGS) on level ground would be a valid mode of exercise testing older adults. Although ETT provides a useful means to risk-stratify adults, age-related declines in gait speed paradoxically limit the utility of standard ETT protocols for evaluating older adults. A customized ETT protocol may be a useful alternative to these standard methods, and this study hypothesized that this alternative approach would be valid. We performed a cross-sectional analysis of baseline data from a randomized controlled trial of older adults with observed mobility problems. Screening was performed using a treadmill-based ETT protocol customized for each individual's HGS. We determined the content validity by assessing the results of the ETTs, and we evaluated the construct validity of treadmill time in relation to the Physical Activity Scale for the Elderly (PASE) and the Late Life Function and Disability Instrument (LLFDI). Outpatient rehabilitation center. Community-dwelling, mobility-limited older adults (N=141). Not applicable. Cardiac instability, ETT duration, peak heart rate, peak systolic blood pressure, PASE, and LLFDI. Acute cardiac instability was identified in 4 of the participants who underwent ETT. The remaining participants (n=137, 68% female; mean age, 75.3 y) were included in the subsequent analyses. Mean exercise duration was 9.39 minutes, with no significant differences in durations being observed after evaluating among tertiles by HGS status. Mean peak heart rate and mean peak systolic blood pressure were 126.6 beats/min and 175.0 mmHg, respectively. Within separate multivariate models, ETT duration in each of the 3 gait speed groups was significantly associated (P<.05) with PASE and LLFDI. Mobility-limited older adults can complete this customized ETT protocol, allowing for the identification of acute cardiac instability and the achievement of optimal exercise parameters.Archives of physical medicine and rehabilitation 02/2012; 93(2):344-50. · 2.18 Impact Factor -
Article: Are changes in leg power responsible for clinically meaningful improvements in mobility in older adults?
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ABSTRACT: From among physiological attributes commonly targeted in rehabilitation, to identify those in which changes led to clinically meaningful differences (CMDs) in mobility outcomes. Secondary analysis of data collected for a randomized controlled trial of exercise using binary outcomes defined by recording a large CMD (Short Physical Performance Battery (SPPB)=1 unit; gait speed (GS)=0.1 m/s). Iterative models were performed to evaluate possible confounding between physiological variables and relevant covariates. Outpatient rehabilitation centers. Community-dwelling mobility-limited older adults (n=116) participating in a 16-week randomized controlled trial of two modes of exercise. Physiological measures included leg power, leg strength, balance as measured according to the Performance-Oriented Mobility Assessment (POMA), and rate pressure product at the maximal stage of an exercise tolerance test. Outcomes included GS and SPPB. Leg power and leg strength were measured using computerized pneumatic strength training equipment and recorded in Watts and Newtons, respectively. Participants were 68% female, had a mean age of 75.2, a mean of 5.5 chronic conditions, and a baseline mean SPPB score of 8.7. After controlling for age, site, group assignment, and baseline outcome values, leg power was the only attribute in which changes were significantly associated with a large CMD in SPPB (odds ratio (OR)=1.48, 95% confidence interval (CI)=1.09-2.02) and GS (OR=1.31, 95% CI=1.01-1.70). Improvements in leg power, independent of strength, appear to make an important contribution to clinically meaningful improvements in SPPB and GS.Journal of the American Geriatrics Society 12/2010; 58(12):2363-8. · 3.74 Impact Factor -
Article: Increased velocity exercise specific to task training versus the National Institute on Aging's strength training program: changes in limb power and mobility.
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ABSTRACT: This study was designed to evaluate the benefits of InVEST (Increased Velocity Specific to Task) training on limb power and mobility among mobility-limited older adults. We conducted a single blinded, randomized controlled trial among 138 mobility-limited community-dwelling older adults, evaluating two 16-week supervised exercise programs. The intervention group participated in InVEST training, and the control group participated in the National Institute on Aging's (NIA) strength training program. Primary outcomes were changes in limb power per kilogram and mobility performance as measured by the Short Physical Performance Battery (SPPB). After 16 weeks, InVEST produced significantly greater improvements in limb power than NIA (p=.02). There was no significant difference in strength improvements. Both groups had significant changes in SPPB of greater than 1 unit. Self-reported function was also significantly improved in both groups. Differences between groups were not statistically different. In a post hoc analysis when participants were categorized by the manifestation of baseline leg velocity impairments (N=68), InVEST training produced effect size differences in SPPB that were clinically meaningful (SPPB Group x Time difference 0.73 units, p=.05). Among mobility-limited older adults, both NIA and InVEST produce robust changes in observed physical performance and self-reported function. These improvements were not meaningfully different by statistical or clinical criteria. Compared with NIA, InVEST training produced greater improvements in limb power and equivalent improvements in strength. Observed differences between NIA and InVEST based upon baseline leg impairment status are informative for futures studies.The Journals of Gerontology Series A Biological Sciences and Medical Sciences 06/2009; 64(9):983-91. · 4.60 Impact Factor -
Article: Which impairments are most associated with high mobility performance in older adults? Implications for a rehabilitation prescription.
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ABSTRACT: To test which rehabilitative impairments are associated with higher mobility performance among community-dwelling, mobility-limited older adults. Cross-sectional analysis of baseline data from participants within a randomized controlled trial. Outpatient rehabilitation research center. Community-dwelling older adults (N=138; mean age, 75.4 y) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Not applicable. Balance measured via the Berg Balance Scale, leg strength, leg velocity, submaximal aerobic capacity, body mass index (BMI), and mobility performance as measured by the SPPB. Each of the 5 physiologic attributes (unipedal balance, leg strength, leg velocity, submaximal aerobic capacity, BMI) was categorized into tertiles by using lower values as reference for impairment status. Within an adjusted model, measures associated with higher SPPB performance (>9) included a BBS score greater than or equal to 54 (odds ratio [OR]=4.54; 95% confidence interval [CI], 1.11-18.60), leg strength greater than or equal to 21.5 N/kg (OR=30.35; 95% CI, 5.48-168.09), leg velocity .0101 to .0129 m.s(-1).kg(-1) (OR=5.31; 95% CI, 1.25-22.57), and leg velocity greater than or equal to .0130 m.s(-1).kg(-1) (OR=22.86; 95% CI, 3.88-134.75). Our investigation highlights the importance of rehabilitative impairments in leg strength, leg velocity, and balance as being associated with mobility status as measured by the SPPB. In our sample of participants within an exercise trial, submaximal aerobic capacity and BMI status were not associated with mobility performance. These findings suggest that the augmentation of not only leg strength and balance but also leg velocity may be important in the rehabilitative care of mobility-limited older adults.Archives of physical medicine and rehabilitation 01/2009; 89(12):2278-84. · 2.18 Impact Factor -
Article: Is stair climb power a clinically relevant measure of leg power impairments in at-risk older adults?
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ABSTRACT: To test the clinical relevance of the stair climb power test (SCPT) as a measure of leg power impairments in mobility-limited older adults. Cross-sectional analysis of baseline data from participants within a randomized controlled trial. Rehabilitation research gym. Community-dwelling older adults (N=138; mean age, 75.4 y) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Not applicable. Leg power measures included the SCPT and double leg press power measured at 40% (DLP40) and 70% (DLP70) of the 1 repetition maximum. Mobility performance tests included the SPPB and its 3 components: gait speed, chair stand time, and standing balance. Stair climb power per kilogram (SCP/kg) had correlations of moderate strength (r=.47, r=.52) with DLP40/kg and DLP70/kg, respectively. All 3 leg power measures correlated with each of the mobility performance measures with the exception of DLP40/kg (r=.11, P=.27) and DLP70/kg (r=.11, P=.18) with standing balance. Magnitudes of association, as described by the Pearson correlation coefficient, did not differ substantively among the separate power measures as they related to SPPB performance overall. Separate adjusted multivariate models evaluating the relationship between leg power and SPPB performance were all statistically significant and described equivalent amounts of the total variance (R(2)) in SPPB performance (SCP/kg, R(2)=.30; DLP40, R(2)=.32; DLP70, R(2)=.31). Analyses of the components of the SPPB show that the SCPT had stronger associations than the other leg power impairment measures with models predicting chair stand (SCP/kg, R(2)=.25; DLP40, R(2)=.12; DLP70, R(2)=.13), whereas both types of leg press power testing had stronger associations with models predicting gait speed (SCP/kg, R(2)=.16; DLP40, R(2)=.34; DLP70, R(2)=.34). Stair climb power was the only power measure that was a significant component of models predicting standing balance (SCP/kg R(2)=.20). The SCPT is a clinically relevant measure of leg power impairments. It is associated with more complex modes of testing leg power impairments and is meaningfully associated with mobility performance, making it suitable for clinical settings in which impairment-mobility relationships are of interest.Archives of Physical Medicine and Rehabilitation 06/2007; 88(5):604-9. · 2.28 Impact Factor
