Brenda Brouwer

Muscle strengthening and physical conditioning to reduce impairment and disability in chronic stroke survivors

OBJECTIVE To evaluate the impact of a program of muscle strengthening and physical conditioning on impairment and disability in chronic stroke subjects. DESIGN A randomized pretest and posttest control group, followed by a single-group pretest and posttest design. SUBJECTS Thirteen community-dwelling stroke survivors of at least 9 months. INTERVENTION A 10-week (3 days/week) program consisting of a warm-up, aerobic exercises, lower extremity muscle strengthening, and a cool-down. MAIN OUTCOME MEASURES Peak isokinetic torque of the major muscle groups of the affected lower limb, quadriceps and ankle plantarflexor spasticity, gait speed, rate of stair climbing, the Human Activity Profile (HAP), and the Nottingham Health Profile (NHP) were recorded twice for the treatment group and three times for the control group. RESULTS Significant improvements were found for all the selected outcome measures (HAP, NHP, and gait speed) for the treatment group (p < .001). In terms of overall training effects, the 13 subjects demonstrated increases in strength of the affected major muscle groups, in HAP and NHP profiles, and in gait speed and rate of stair climbing without concomitant increases in either quadriceps or ankle plantarflexor spasticity. CONCLUSIONS The 10-week combined program of muscle strengthening and physical conditioning resulted in gains in all measures of impairment and disability. These gains were not associated with measurable changes of spasticity in either quadriceps or ankle plantarflexors.

Isokinetic strength training of the hemiparetic knee: Effects on function and spasticity

PURPOSE To determine whether isokinetic training can improve the strength of the hemiparetic knee musculature, functional mobility, and physical activity and to evaluate its effect on spasticity in long-term stroke survivors. DESIGN Nonrandomized self-controlled trial. SUBJECTS A volunteer sample of 15 community-dwelling stroke survivors of at least 6 months. INTERVENTION A 6-week (3 days/week, 40 minutes/day) program consisting of warm-up, stretches, reciprocal knee extension and flexion isokinetic strengthening, and cool-down for the paretic limb. MAIN OUTCOME MEASURES Peak isokinetic hamstring and quadriceps torque, quadriceps spasticity, gait velocity, timed Up and Go, timed stair climb, and the Human Activity Profile (HAP) scores were recorded at baseline, after training, and 4 weeks after training cessation (follow-up). RESULTS Paretic muscle strength improved after training (p < .05) while tone remained consistent (p > .87). Gait velocity increased after training (p < .05) and at follow-up (p < .05). Changes in stair climbing and timed Up and Go were not significant (p > .37; p > .91), although subjects perceived gains in their physical abilities at follow-up (p < .01). CONCLUSIONS Gains in strength and gait velocity without concomitant increases in muscle tone are possible after a short-term strengthening program for stroke survivors. The psychological benefit associated with physical activity is significant.

Reliability and Validity of Measures Obtained From Stroke Patients Using the Balance Master

OBJECTIVE To determine the test-retest reliability and validity of data obtained using the Balance Master (BM), a computerized balance assessment and training tool. DESIGN Data were collected on three occasions, 1 week apart. Intraclass correlation coefficients (ICCs) were calculated if significant (p < .05) between-subject variance was found using a univariate analysis of variance for repeated measures. Concurrent validity of the BM data was determined using the Berg Balance Scale and gait velocity as criterion standards. PARTICIPANTS Twenty ambulatory hemiparetic subjects who had no history of lower extremity orthopedic problems, no neurological deficits apart from stroke, and had not trained using the BM. MAIN OUTCOME MEASURES BM data relating to static and dynamic balance performance, gait velocity, and the total score from the Berg Balance Scale. RESULTS ICCs indicated that only the BM test requiring subjects to shift their center of gravity to randomly highlighted targets (positioned in a circle representing 75% of the individuals limits of stability) was reliable, both in terms of movement path (ICC = .84) and movement time (ICC = .88). Concurrent validity of the BM data was established for the dynamic measures of balance only, which correlated with both the Berg Balance Scale and gait velocity outcomes (r > or = .48, p < .05). CONCLUSIONS These findings suggest that in stroke patients the test-retest reliability of data obtained using the BM is greatest for complex tests of balance and that dynamic rather than static balance measures are valid indicators of functional balance performance.

Corticospinal projections to lower limb motoneurons in man

SummaryThe projections of cortical neurons activated by transcranial magnetic stimulation to single lower limb spinal motoneurons were examined in 34 normal subjects. Peristimulus time histograms of the discharge times of single, voluntarily activated motor units were used to derive information about postsynaptic potentials in single spinal motoneurons produced by magnetic stimuli applied over the contralateral scalp. All tibialis anterior motor units and the majority of motoneurons innervating the small muscles of the foot showed strong short latency facilitation. About half of the motoneurons of proximal lower limb muscles showed this facilitation. Short latency facilitation of the motoneurons of soleus and medial gastrocnemius was only rarely observed and when present was weak. The short latency facilitation is attributed to the projections of the fast corticospinal pathway with monosynaptic projections to motoneurons. The relative strength of the facilitation in different motoneuron pools is considered to reflect the density of corticospinal projections to that motoneuron pool. The observed pattern of projections in man shows some differences from the pattern of projections in subhuman primates that might reflect the different use of the limb.

Physical Function and Health Status among Seniors with and without a Fear of Falling

Background: Fear of falling (FF) is pervasive among older people and is an independent risk factor for decreased mobility and loss of quality of life. Although it is a serious health concern, little is known about the severity of the physical and health-related deficits in high-functioning fearful seniors. Objective: This study examined the physical correlates of FF in community-dwelling seniors in relation to their non-fearful counterparts and also explored the relevance of recent fall history. Subjects: Twenty-five volunteers who stated that they had curtailed their activities due to a FF and who reported themselves to be healthy participated. Non-fearful, age- and gender-matched subjects were also recruited and served as a comparison group. Methods: This cross-sectional study had participants come to the laboratory on one occasion for about 1.5 h. Limits of balance stability, walking speed, and lower limb muscle strength were measured in random order. In addition, the SF-36, the Activities-specific Balance Confidence (ABC) scale and the Human Activity Profile questionnaires were completed to provide measures of heath status, FF and activity levels, respectively. Results: Subjects with a FF had lower ABC scores (69.8 ± 10.2) than controls (90.2 ± 7.9; p < 0.001), and although they reported activity curtailment, the groups presented similar activity profiles (p > 0.05). Balance ability was not compromised in seniors with a FF, although their walking speed was slower than that of control subjects (p < 0.004). Lower limb weakness was significant in the FF group, which also reported low physical health. Perceived physical health, activity and hip flexor torque in combination accounted for almost 62% of the variance in ABC scores. Secondary analysis of the data from the FF group revealed a tendency for those who had fallen in the past year to restrict their limits of stability compared to those who had not fallen; though generally the effect sizes were small to moderate. Conclusions: The marked deficits in strength and health status found among seniors living independently in the community, who are in good health, but report being fearful of falling underscores the seriousness of FF as a potential health risk factor in the well elderly.

Reducing fear of falling in seniors through education and activity programs: a randomized trial.

OBJECTIVES: To determine the relative effect of education and activity programs on fear of falling, balance, strength, and health status.

Primary motor cortex underlies multi-joint integration for fast feedback control

A basic difficulty for the nervous system is integrating locally ambiguous sensory information to form accurate perceptions about the outside world. This local-to-global problem is also fundamental to motor control of the arm, because complex mechanical interactions between shoulder and elbow allow a particular amount of motion at one joint to arise from an infinite combination of shoulder and elbow torques. Here we show, in humans and rhesus monkeys, that a transcortical pathway through primary motor cortex (M1) resolves this ambiguity during fast feedback control. We demonstrate that single M1 neurons of behaving monkeys can integrate shoulder and elbow motion information into motor commands that appropriately counter the underlying torque within about 50 milliseconds of a mechanical perturbation. Moreover, we reveal a causal link between M1 processing and multi-joint integration in humans by showing that shoulder muscle responses occurring ∼50 milliseconds after pure elbow displacement can be potentiated by transcranial magnetic stimulation. Taken together, our results show that transcortical processing through M1 permits feedback responses to express a level of sophistication that rivals voluntary control; this provides neurophysiological support for influential theories positing that voluntary movement is generated by the intelligent manipulation of sensory feedback.

Kinematic, kinetic and metabolic parameters of treadmill versus overground walking in healthy older adults

BACKGROUND Although treadmill and overground walking appear to be biomechanically similar in healthy, young adults it is not known whether this can be generalized to older subjects or if the metabolic demands are correspondingly comparable. METHODS Ten healthy adults between 50 and 73 years of age walked at the same speed overground and on a treadmill. Temporal parameters, angular kinematics and vertical ground reaction forces were recorded during walking once subjects were in steady state as determined from their heart rate and oxygen uptake. FINDINGS Step, stride and joint angular kinematics were similar for both modes of walking with the exception of the maximum hip flexion and knee extension which were more pronounced with treadmill or overground walking, respectively but in both instances differed by less than 3 degrees. Vertical ground reaction force profiles were similar although the peak associated with push-off was 5.5% smaller with treadmill walking. The metabolic requirements of treadmill walking were about 23% higher than that associated with overground walking. INTERPRETATION While treadmill and overground walking are biomechanically similar, the metabolic cost of treadmill walking is higher. Clinically this may be important when using a treadmill for gait retraining in patient populations as it may lead to premature fatigue or undesirable physiologic challenge.

Fatigue secondary to chronic illness: Postpolio syndrome, chronic fatigue syndrome, and multiple sclerosis

Estimates of the percentage of patients with postpolio syndrome, chronic fatigue syndrome, and multiple sclerosis who experience fatigue range from approximately 75% to 100%. In this study we describe the severity of fatigue and its impact on subjects with these three diagnoses. The Fatigue Severity Scale, the Human Activity Profile, and the Nottingham Health Profile were used to measure fatigue, activity, and health status respectively of each diagnostic group as well as a control group. Using a Kruskal-Wallis one-way analysis of variance followed by a Bonferroni-adjusted Mann Whitney U test all diagnostic groups reported significantly higher levels (p = .0000 to p = .002) of fatigue and lower perceived health status than the control group. Subjects with chronic fatigue and multiple sclerosis also had significantly reduced activity levels (p = .002 to p = .01) compared with the control group. Further attention should be directed toward understanding the relationship between fatigue and ability to engage in activities as well as strategies for remediation and/or compensation of the fatigue.

Validity of the Community Balance and Mobility Scale in Community-Dwelling Persons After Stroke

OBJECTIVES To examine the convergent validity, sensitivity to change, floor and ceiling effects of the Community Balance and Mobility Scale (CB&M) in community-dwelling stroke survivors. The secondary objective was to determine the correlations between the CB&M and lower-limb motor recovery and strength. DESIGN Validity study. SETTING Two university-based research centers. PARTICIPANTS Community-dwelling persons after stroke (N=44; 24 men, 20 women; mean age, 62.6+/-12.6y). Baseline measures were taken 3 months after the onset of stroke (98.6+/-52.6d); participants were reassessed 8 months poststroke (246.8+/-57.2d). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES CB&M, Berg Balance Scale (BBS), Timed Up & Go (TUG), Chedoke McMaster Stroke Assessment (CMSA) Impairment Inventory for leg and foot, concentric bilateral isokinetic strength of the lower-limb flexor and extensor muscle groups using a dynamometer. The magnitude of the associations and the standardized response means (SRMs) among the CB&M, BBS, and TUG were used to examine the convergent validity and sensitivity to change, respectively. RESULTS Moderate to high convergent validities (rho=.70 to .83, P<.001) were observed among the CB&M, BBS, and TUG. The CB&M was moderately correlated with the CMSA leg and foot scores (rho=.61 and .63, respectively, P<.001) and the paretic limb strength (rho=.67, P<.001). The CB&M demonstrated the greatest ability to detect change between the baseline and follow-up assessments (SRM=.83). CONCLUSIONS The CB&M is valid and sensitive to change in assessing functional balance and mobility in ambulatory stroke survivors with moderate to mild neurologic impairments.