Feasibility of lower-limb muscle power training to enhance locomotor function poststroke.

Poststroke motor control is characterized by greatly reduced muscle power generation. To date, the extent to which muscle power limits walking performance or whether its remediation should be a primary component of locomotor rehabilitation has yet to be established. The purpose of this study was to examine the feasibility and the effects of Poststroke Optimization of Walking using Explosive Resistance training, an intervention aimed at improving poststroke muscular and locomotor function. Twelve subjects (6-60 mo poststroke) participated in 24 training sessions (3 sessions/wk for 8 wk). Exercises included leg press, calf raises, and jump training, all performed at high concentric velocity, as well as trials of fast walking. We measured self-selected and fastest comfortable walking speeds as well as knee extensor and plantar flexor strength and power at pretraining, posttraining, and 8 wk follow-up time points. In addition, we also performed a number of clinical assessments commonly used in poststroke rehabilitation trials. Following training, significant improvements in lower-limb muscle strength and power were realized and accompanied by improvements in self-selected as well as fastest comfortable walking speeds. No changes in clinical assessments resulted from training.

Lower Extremity Strength Is Correlated with Walking Function After Incomplete SCI.

BACKGROUND: Lower extremity strength has been reported to relate to walking ability, however, the relationship between voluntary lower extremity muscle function as measured by isokinetic dynamometry and walking have not been thoroughly examined in individuals with incomplete spinal cord injury (iSCI). OBJECTIVE: To determine the extent to which measures of maximal voluntary isometric contraction (MVIC) and rate of torque development (RTD) in the knee extensor (KE) and plantar flexor (PF) muscle groups correlate with self-selected overground walking speed and spatiotemporal characteristics of walking. METHODS: Twenty-two subjects with chronic (>6 months) iSCI participated in a cross-sectional study. Values for MVIC and RTD in the KE and PF muscle groups were determined by isokinetic dynamometry. Walking speed and spatiotemporal characteristics of walking were measured during overground walking. RESULTS: MVIC in the KE and PF muscle groups correlated significantly with walking speed. RTD was significantly correlated with walking speed in both muscle groups, the more-involved PF muscle group showing the strongest correlation with walking speed (r = 0.728). RTD in the KE and PF muscle groups of the more-involved limb was significantly correlated with single support time of the more-involved limb. CONCLUSIONS: These data demonstrate that lower extremity strength is associated with walking ability after iSCI. Correlations for the muscle groups of the move-involved side were stronger compared to the less-involved limb. In addition, PF function is highlighted as a potential limiting factor to walking speed along with the importance of RTD.

Differential adaptations of muscle architecture to high-velocity versus traditional strength training in cerebral palsy.

BACKGROUND: Everyday activities for youth with cerebral palsy (CP) require muscle power, but the velocity component of muscle contraction is neglected with traditional strength training (ST). OBJECTIVE: To determine whether velocity training (VT), which includes resistance training at increasingly higher velocities, would induce specific muscle adaptations not observed with ST. METHODS: Sixteen ambulatory youth with CP were randomized to VT or ST. Participants trained the knee extensors 3 times per week for 24 sessions on a Biodex dynamometer. At each session, 6 sets of 5 concentric repetitions were performed either at 30 deg/s (ST group) or progressively higher velocities from 30 deg/s to 120 deg/s (VT group). Outcomes included muscle architecture, power, strength, walking speed, and functional walking performance. RESULTS: A significant increase in rectus femoris fascicle length was observed after VT with a decrease after ST. Rectus femoris cross-sectional area increased in both groups. Both showed significant increases in isokinetic strength at all tested speeds; however, peak velocity and power improved after VT only. Self-selected and fast walking speed and functional walking performance improved after VT only. CONCLUSIONS: Muscle architecture in CP is capable of adapting differentially to the training stimulus. VT was equally effective as traditional ST in improving isokinetic strength of the knee extensors but more effective in improving velocity of movement, muscle power, and walking performance. Differences may be partially attributed to specificity of training effects on muscle architecture, such as the increase in fascicle length after VT. Strengthening interventions involving higher velocity movements should be incorporated into clinical practice.

The process associated with motivation of a home-based Wii Fit exercise program among sedentary African American women with systemic lupus erythematosus.

OBJECTIVE: To explore the process associated with the motivation for playing Wii Fit among patients with systemic lupus erythematosus (SLE). METHODS: Individual in-depth semi-structured telephone interviews were conducted with 14 sedentary African American women with SLE to explore their experiences and reflect on their motivation for playing Wii Fit after completing a 10-week home-based Wii Fit exercise program. Interviews were audio-recorded, transcribed verbatim, and analyzed using the constant comparative method to identify categories related to participants' motivation. Three authors independently sorted, organized and coded transcript text into categories, then combined the categories into themes and subthemes. RESULTS: In addition to the two themes (Ethical principal of keeping a commitment, and Don't want to let anyone down) generic to home-based exercise trials, we identified five themes (Enjoyment, Health Benefits, Sense of Accomplishment, Convenience, and Personalized) that revealed why the participants were motivated to play the Wii Fit. Enjoyment had three subthemes: Interactive, Challenging, and Competitive with an embedded social element. However, several participants commented they were not able to do many activities, master certain games, or figure out how to play some; as a result, they were bored with the limited selection of activities that they could do. CONCLUSIONS: The motivational elements of the Wii Fit may contribute to improved exercise motivation and adherence in select sedentary African American women with SLE. Results provide a better understanding on the important elements to incorporate in the development of sustainable home-based exercise programs with interactive health video games for this population.

Self-reported versus objectively assessed exercise adherence.

OBJECTIVE. We examined agreement of data between self-reported and objectively assessed exercise adherence among women with systemic lupus erythematosus. METHOD. Eleven participants completed weekly exercise logs on date and duration of exercise during a 10-wk Wii Fit™ home-based program. Afterward, exercise data from the log were compared with those recorded in the Wii console. RESULTS. Of the paired data, the mean duration of exercise recorded in the Wii was 29.5 min and that recorded in the log was 33.3 min. The composite intraclass correlation for exercise duration between exercise log and the Wii Fit was 0.4. The 95% limits of agreement indicated large between-subjects variability. CONCLUSION. Exercise logs exhibit a marginally acceptable agreement with Wii estimation of exercise duration at a group level. However, caution should be applied when using the exercise log as a measure of a person's exercise behavior because of the tendency to overreport.