Biomedical subjects

Walter R Frontera

Publications and source records attributed to Walter R Frontera.

44 records · Page 3Linked to original sources

PubMed2002

Skeletal muscle fiber function and rate of disease progression in amyotrophic lateral sclerosis.

The contractile properties of single muscle fibers reflect the functional status of muscle at the cellular level and have not been described in amyotrophic lateral sclerosis (ALS). Chemically skinned single muscle fibers (n = 173), obtained by needle biopsy from six men with ALS, were activated with Ca(2+), allowing maximal force measurements and specific force (SF) estimates. Maximum unloaded shortening velocity (V(o)) was determined using the slack test. The results were compared with muscle from healthy controls. Markers of disease progression included rate of change of ALS functional rating scale score, rate of change of forced vital capacity, and disease duration. Compared with controls, ALS patients had decreased whole muscle SF (measured by a combination of computerized tomography and isokinetic testing) but normal single fiber SF. The V(o) was greater for type I fibers in ALS. Patients with slower disease progression had increased single fiber size and a high percentage of hybrid fibers (expressing multiple myosin heavy chain isoforms). A needle biopsy obtained at the time of ALS diagnosis may assist with predicting rate of disease progression.

Adult↗

PubMed2002

The relationship between leg power and physical performance in mobility-limited older people.

OBJECTIVES: 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. DESIGN: Cross-sectional analysis of baseline data from a 12-week randomized controlled exercise-intervention study. SETTING: Exercise laboratory within the Department of Health Science of an urban university. PARTICIPANTS: Forty-five community-dwelling mobility-limited people (34 women, 11 men), aged 65 to 83. MEASUREMENTS: Health status, depression, cognition, physical activity, and falls efficacy; physiological measures of lower extremity strength and power; and measures of physical performance. RESULTS: Through bivariate analyses, leg power was significantly associated with physical performance as measured by stair-climb time, chair-stand time, tandem gait, habitual gait, maximal gait, and the short physical performance battery describing between 12% and 45% of the variance (R2). Although leg power and leg strength were greatly correlated (r = .89) in a comparison of bivariate analyses of strength or power with physical performance, leg power modeled up to 8% more of the variance for five of six physical performance measures. Despite limitations in sample size, it appeared that, through quadratic modeling,the influence of leg power on physical performance was curvilinear. Using separate multivariate analyses, partial R2 values for leg power and leg strength were compared, demonstrating that leg power accounted for 2% to 8% more of the variance with all measures of physical performance. CONCLUSION: Leg power is an important factor influencing the physical performance of mobility-limited older people. Although related to strength, it is a separate attribute that may exert a greater influence on physical performance. These findings have important implications for clinicians practicing geriatric rehabilitation.

Age Factors↗

PubMed2002

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. DESIGN: Single-blinded, randomized controlled pilot study. SETTING: Human physiology laboratory of a metropolitan university. PARTICIPANTS: Forty-five community-dwelling people aged 65 and older who had baseline mobility limitations manifested by scores of 11 or lower on the Short Physical Performance Battery (SPPB). INTERVENTIONS: Subjects were randomized into one of two 12-week exercise programs. The intervention group (SCE) (n = 23) ascended and descended stairs, at a set pace, while wearing a weighted vest. The control group (WALK) (n = 22) participated in a standardized walking program. MEASUREMENTS: Primary and secondary outcomes included measures of muscle power and strength, submaximal aerobic capacity, and physical performance. RESULTS: SCE produced 17% improvement in double leg press peak power in comparison with WALK (P =.013) and significant improvement in stair climbing power from baseline (12%). Improvement in submaximal aerobic performance was equivalent for both groups. Although not statistically significant, effect size estimates suggest that SCE can potentially influence knee extension power and strength. Stair climb time was improved in both groups, whereas SCE produced significant improvements from baseline SPPB score in a subcohort of participants. CONCLUSIONS: These findings suggest that SCE maybe a useful component of a home exercise program designed to enhance lower extremity muscle power, aerobic capacity, and functional performance. Further investigation is needed involving larger sample sizes and direct comparisons with other forms of resistance training.

Aged↗

PubMed2002

Longitudinal changes in body composition in older men and women: role of body weight change and physical activity.

BACKGROUND: Estimates of body-composition change in older adults are mostly derived from cross-sectional data. OBJECTIVE: We examined the natural longitudinal patterns of change in fat-free mass (FFM) and fat mass (FM) in older adults and explored the effect of physical activity, weight change, and age on these changes. DESIGN: The body composition measured by hydrodensitometry and the level of sports and recreational activity (SRA) of 53 men and 78 women with a mean (+/-SD) initial age of 60.7 +/- 7.8 y were examined on 2 occasions separated by a mean (+/-SD) time of 9.4 +/- 1.4 y. RESULTS: FFM decreased in men (2.0% per decade) but not in women, whereas FM increased similarly in both sexes (7.5% per decade). Levels of SRA decreased more in men than in women over the follow-up period. Baseline age and level of SRA were inversely and independently associated with changes in FM in women only. Neither age nor level of SRA was associated with changes in FFM in men or women. Weight-stable subjects lost FFM. FFM accounted for 19% of body weight in those who gained weight, even in the presence of decreased levels of SRA. Loss of FFM (33% of body weight) was pronounced in those who lost weight, despite median SRA levels >4184 kJ/wk. CONCLUSIONS: On average, FM increased; however, the increase in women was attenuated with advancing age. The decrease in FFM over the follow-up period was small and masked the wide interindividual variation that was dependent on the magnitude of weight change. The contribution of weight stability, modest weight gains, or lifestyle changes that include regular resistance exercise in attenuating lean-tissue loss with age should be explored.

Adipose Tissue↗

PubMedDate not supplied

Motions or muscles? Some behavioral factors underlying robotic assistance of motor recovery.

Robotics and related technologies have begun to realize their promise to improve the delivery of rehabilitation therapy. However, the mechanism by which they enhance recovery remains unclear. Ultimately, recovery depends on biology, yet the details of the recovery process remain largely unknown; a deeper understanding is important to accelerate refinements of robotic therapy or suggest new approaches. Fortunately, robots provide an excellent instrument platform from which to study recovery at the behavioral level. This article reviews some initial insights about the process of upper-limb behavioral recovery that have emerged from our work. Evidence to date suggests that the form of therapy may be more important than its intensity: muscle strengthening offers no advantage over movement training. Passive movement is insufficient; active participation is required. Progressive training based on measures of movement coordination yields substantially improved outcomes. Together these results indicate that movement coordination rather than muscle activation may be the most appropriate focus for robotic therapy.

Behavior↗

PubMedDate not supplied

Rehabilitation Medicine Summit: Building Research Capacity-Executive Summary.

The general objective of the "Rehabilitation Medicine Summit: Building Research Capacity" was to advance and promote research in medical rehabilitation by making recommendations to expand research capacity. The five elements of research capacity that guided the discussions were (1) researchers; (2) research culture, environment, and infrastructure; (3) funding; (4) partnerships; and (5) metrics. The 100 participants included representatives of professional organizations, consumer groups, academic departments, researchers, governmental funding agencies, and the private sector. The small group discussions and plenary sessions generated an array of problems, possible solutions, and recommended actions. A post-Summit, multiorganizational initiative is called to pursue the agendas outlined in this report.

Biomedical Research↗

PubMedDate not supplied

Rehabilitation Medicine Summit: Building Research Capacity: executive summary.

The general objective of the "Rehabilitation Medicine Summit: Building Research Capacity" was to advance and promote research in medical rehabilitation by making recommendations to expand research capacity. The five elements of research capacity that guided the discussions were: (1) researchers; (2) research culture, environment, and infrastructure; (3) funding; (4) partnerships; and (5) metrics. The 100 participants included representatives of professional organizations, consumer groups, academic departments, researchers, governmental funding agencies, and the private sector. The small group discussions and plenary sessions generated an array of problems, possible solutions, and recommended actions. A post-Summit, multi-organizational initiative is called to pursue the agendas outlined in this report.

Allied Health Occupations↗

PubMedDate not supplied

Rehabilitation medicine summit: building research capacity.

The general objective of the "Rehabilitation Medicine Summit: Building Research Capacity" was to advance and promote research in medical rehabilitation by making recommendations to expand research capacity. The 5 elements of research capacity that guided the discussions were (1) researchers; (2) research culture, environment, and infrastructure; (3) funding; (4) partnerships; and (5) metrics. The 100 participants included representatives of professional organizations, consumer groups, academic departments, researchers, governmental funding agencies, and the private sector. The small group discussions and plenary sessions generated an array of problems, possible solutions, and recommended actions. A post-Summit, multiorganizational initiative is called to pursue the agendas outlined in this article.

Biomedical Research↗