Factors related to daily step counts of stroke patients during hospitalization in a convalescent rehabilitation ward.

OBJECTIVES: Clarifying the factors related to decreased physical activity in post-stroke patients is essential for effective disease management. This study aimed to examine the factors influencing the amount of daily steps taken by post-stroke patients in a convalescent rehabilitation ward during activities other than rehabilitation (non-rehabilitation steps). MATERIALS AND METHODS: Eighty-nine post-stroke patients (60.8±14.4 years; 55 men) were enrolled. The inclusion criteria were walking independently within the ward and having a walking speed of ≥24 m/min. Data on patient clinical characteristics including age, sex, body mass index, stroke type, hemiparetic side, and time from stroke onset were collected. Stroke impairment and motor and cognitive functional disabilities were assessed using the Stroke Impairment Assessment Set and the Functional Independence Measure, respectively. The non-rehabilitation steps were calculated by subtracting the steps during the rehabilitation activities from the total steps using Fitbit Flex2. RESULTS: The average number of non-rehabilitation steps was 4,523±2,339 steps/day. The hierarchical multiple regression analysis revealed that sex, motor disability, and the interaction term of stroke impairment with cognitive disability were significantly related to non-rehabilitation steps. Simple slope analysis demonstrated that the stroke impairment slope was steeper at lower levels than at higher levels of cognitive disability for non-rehabilitation steps. CONCLUSIONS: In addition to independent effects of sex and motor disability, this study found that stroke impairment and cognitive disability were interactively related to non-rehabilitation steps in post-stroke patients in a convalescent rehabilitation ward. These findings may provide useful information for managing physical activity in post-stroke patients after hospital discharge.

The effects of skin cold stimulation on quadriceps muscle activity during walking in older adults.

Purpose: Given that walking speed declines with ageing and decreasing walking speed restricts activities of daily living (ADL), it is important for the old to maintain walking speed in order to prevent affecting ADL. Although skin cold stimulation (SCS) facilitates instantaneous muscle activity, which occurs during walking, the effects of SCS on muscle activity during walking remain unclear. Thus, the present study aimed to investigate the effect of SCS during walking in older adults.Methods: Seventeen community-dwelling healthy older adults (73 ± 6 years old) participated in this study. Walking speed at a comfortable pace and the electromyographic (EMG) activity of the vastus lateralis (VL) and biceps femoris (BF) were measured. SCS, which maintains the skin temperature at 25 °C, was applied to the front of the thigh during the procedures. Walking speed, root mean square EMG (rmsEMG) and mean power frequency (MPF) were compared under SCS and control conditions.Results: SCS significantly increased the walking speed (p < 0.01) and the rmsEMG of the vastus lateralis (p = 0.032). No change in the rmsEMG of the BF was observed, and SCS had no effect on MPF of both the VL and BF. Furthermore, a significant relationship was observed between these changes (r = 0.619, p = 0.042).Conclusion: SCS increased the EMG activity of the VL while increasing walking speed. Our results suggest that SCS is an effective strategy that can be included in daily life in order to improve walking ability of older adults.

Change in EMG with skin friction at different frequencies during elbow flexion.

Modulation of muscle activation in superficial and deeper regions may be induced by tactile stimulation. The purpose of this study was to examine changes in muscle activation with skin friction. Subjects performed an isometric elbow flexion at 30% maximal voluntary cotraction (MVC) with skin friction at different frequencies (0.5-2.7 Hz). Surface electromyography (S-EMG) and intramuscular EMG were obtained from the elbow flexor muscles (BBS: short head of biceps brachii, BBL: long head of biceps brachii, BRA: brachialis). S-EMG activity decreased at a higher frequency of 2.7 Hz and increased linearly with an increase in skin friction frequency (0.5-2.7 Hz) in BBS. A decrease in high-threshold motor unit (HT-MU) firing rate in superficial regions and an increase in low-threshold motor unit (LT-MU) firing rate in deeper regions were observed with skin friction (2.7 Hz) in BBS. The actions of inhibitory interneurons may be influenced by cutaneous afferent input with skin friction. Muscle activation of BBS depended on the intensity of the stimulus. Skin friction over BBS results in an inhibitory response in superficial regions of BBS, most likely due to the increase in firing rate of low-threshold cutaneous mechanoreceptors.

Effect of submaximal isometric wrist extension training on grip strength.

Gripping force is produced by co-contraction of forearm flexors and extensors. Activation of extensors is important for stabilizing the wrist during gripping. However, forearm muscle function is complicated and the neurophysiological mechanism responsible for the gain in gripping force is unclear. Therefore, the purpose of this study was to investigate whether increasing forearm extensor activation with isometric wrist extension training has an effect on gripping force. Thirteen healthy subjects participated in this study. Maximal voluntary contraction of gripping was measured using a piezosensor (MVC(grip)) and EMG of forearm muscles at every wrist angle (from 70° flexion to 80° extension with 10° intervals) were measured simultaneously at baseline, 4 weeks, and 8 weeks after training. Training consisted of 30 repetitions equal to 70% MVC of isometric wrist extension for 8 weeks (5/week) on the right side. Gripping force was measured on both sides using a grip dynamometer without wrist angle restriction. Gripping force, EMG, maximal wrist extension force, and wrist angle-gripping force curve were investigated after training. After training, maximal wrist extension force increased significantly. Gripping force on the trained side also increased significantly. The training changed wrist angle at peak of MVC(grip). EMG activation of forearm extensors increased and that of flexors decreased during gripping. These results suggest that wrist extension training leads to an increase in gripping force and changes the balance of EMG activation between forearm flexors and extensors during gripping. Therefore, this training method should be useful as a therapeutic strategy for increasing grip strength.

Decreased rate of leg extensor force development in independently ambulant patients with acute stroke with mild paresis.

We aimed to examine the rate of force development (RFD) of knee extensors on both sides in independently ambulant patients with acute stroke with mild paresis compared with that in age-matched healthy adults. A total 31 patients with acute stroke history (patient group: 67 ±â€¯12 years) and 54 age-matched healthy, community-dwelling adults (control group: 67 ±â€¯8 years) were included. Maximum voluntary contraction (MVC) and RFD were assessed <1 month post-stroke during isometric knee extension (sitting position; 90° knee flexion) using a hand-held dynamometer. RFD was measured as the average slope of the torque-time curve over time intervals of 0-50 ms and 0-200 ms from contraction onset. In the patient group, MVC and RFD for 0-50 ms were significantly lower on the affected side than on the unaffected side (p < 0.01). RFD was significantly decreased in the patient group, to 32%-38% and 62%-71% of that in the control group, over 0-50 ms and 0-200 ms, respectively, regardless of the affected side (p < 0.01). No significant differences in MVC between patient and control groups were observed for either side. RFD of the knee extensors significantly decreased without MVC reduction in patients with acute stroke history compared with that in age-matched healthy adults in both the affected and unaffected sides. These results suggest that decrease in RFD was initiated from the acute phase of stroke, even in patients with stroke who had good motor function.

Increase in rate of force development with skin cooling during isometric knee extension.

Rate of force development (RFD) plays an important role when performing rapid and forceful movements. Cold-induced afferent input with transient skin cooling (SC) can modulate neural drive. However, the relationship between RFD and SC is unknown. The purpose of this study was to investigate whether SC increases RFD during isometric knee extension. Fifteen young healthy men (25 ± 8 yrs old) contracted their quadriceps muscle as fast and forcefully as possible with or without SC. Skin cooling was administered to the front of the thigh. Torque and electromyographic activity were measured simultaneously. Peak torque was not affected by SC. Skin cooling induced a significant increase in RFD at the phase 0-30 and 0-50 ms. The root mean square of the electromyography of vastus medialis, rectus femoris and vastus lateralis at the phases 0-30-50-100 ms increased significantly or tended to increase with SC. These results suggest that SC may increase neural drive and improve RFD in the very early phases of contraction.