Changes of heart rate variability and prefrontal oxygenation during Tai Chi practice versus arm ergometer cycling.

[Purpose] Exercise has been shown to improve cardiovascular fitness and cognitive function. Whether the inclusion of mind over exercise would increase parasympathetic control of the heart and brain activities more than general exercise at a similar intensity is not known. The aim of this study was to compare the effects of Tai Chi (mind-body exercise) versus arm ergometer cycling (body-focused exercise) on the heart rate variability and prefrontal oxygenation level. [Subjects and Methods] A Tai Chi master was invited to perform Tai Chi and arm ergometer cycling with similar exercise intensity on two separate days. Heart rate variability and prefrontal oxyhemoglobin levels were measured continuously by a RR recorder and near-infrared spectroscopy, respectively. [Results] During Tai Chi exercise, spectral analysis of heart rate variability demonstrated a higher high-frequency power as well as a lower low-frequency/high-frequency ratio than during ergometer cycling, suggesting increased parasympathetic and decreased sympathetic control of the heart. Also, prefrontal oxyhemoglobin and total hemoglobin levels were higher than those during arm ergometer exercise. [Conclusion] These findings suggest that increased parasympathetic control of the heart and prefrontal activities may be associated with Tai Chi practice. Having a "mind" component in Tai Chi could be more beneficial for older adults' cardiac health and cognitive function than body-focused ergometer cycling.

Effect of dual tasking on intentional vs. reactive balance control in people with hemiparetic stroke.

To examine the effect of a cognitive task on intentional vs. reactive balance control in people with hemiparetic stroke (PwHS). Community-dwelling PwHS (n = 10) and healthy, age-similar controls performed two tests, which included the Limits of Stability Test (intentional control) and the Motor Control Test (reactive control), under single-task (ST) and dual-task (DT) conditions (addition of a cognitive task). Cognitive ability was measured on a word list generation task by recording the number of words enumerated in sitting (ST; for cognition) and during the balance tasks. The difference in response time between the ST and DT, defined as the "balance cost" was obtained [(ST - DT)/ST × 100] and compared between tests and across groups. The "cognitive cost" was similarly defined and compared. For both groups, the response time under DT condition was significantly greater for intentional than the reactive balance control task, leading to a higher balance cost for this task (P < 0.05). However, the cognitive cost was significantly greater for the intentional than the reactive balance control task for only the PwHS. DT significantly affected intentional than reactive balance control for PwHS. The significant decrease in both balance and cognitive performance under DT compared with ST conditions during intentional balance control suggests sharing of attentional resources between semantic memory and intentional balance control. Decreased performance on the cognitive task only during the reactive balance test indicates possible central nervous system's prioritization of reactive balance control over cognition.

Are there any relationships among ankle proprioception acuity, pre-landing ankle muscle responses, and landing impact in man?

Proprioceptive input has been suggested to contribute to the pre-landing muscle responses associated with drop-landing, but its precise role has yet to be delineated. This study set out to examine the relationships among ankle proprioception, pre-landing muscle responses, and landing impact on drop-landing in healthy man. Fifteen healthy male basketball players aged 18 to 26 participated in this study. Passive ankle joint repositioning errors were used to examine ankle joint proprioception. Pre-landing EMG responses in the ankle muscles and the impact force on landing were recorded while the players performed self-initiated drops from a height of 30 cm. Results demonstrated that averaged ankle repositioning errors were significantly correlated with the co-contraction indexes between left tibialis anterior and medial gastrocnemius muscles (TA/MG CoI) (r=0.67, p=0.006), and showed a trend towards a relationship with the right TA/MG CoI (r=0.47, p=0.079). TA/MG CoI from both ankles were further related to the magnitude of the total impact force on landing (r=0.54 and 0.53, respectively; p<0.05). We concluded that male basketball players with less accurate ankle joint sense adopted greater co-contraction of ankle dorsiflexors and platarflexors, which was in turn associated with greater impact force at the moment of landing.

[Effects of functional electrical stimulation on the improvement of motor function of patients with acute stroke: a randomized controlled trial].

OBJECTIVE: To investigate the effects of functional electrical stimulation (FES) on the improvement of motor and walking ability of the lower extremities of the patients with acute stroke. METHODS: Forty-six patients with stroke (including cerebral infarction and hemorrhage), aged 71 +/- 8 (45 - 84), hospitalized within 2 weeks (9 +/- 4 days) after the onset, matched with one another in the baseline measurements before treatment, were assigned randomly into 3 groups: FES group (n = 13), receiving standard rehabilitation combined with FES 30 minutes per day, 5 days per week for 3 weeks, placebo stimulation group (n = 15) receiving standard rehabilitation combined with the installment of the FES apparatus, operated in the same manner as mentioned above, however, without real electric stimulation, and control group (n = 13), receiving standard rehabilitation alone. The score of the composite spasticity scale (CSS) was measured, electromyography was conducted to measure the maximum isometric voluntary contraction (MIVC) of the ankle dorsi-flexors and plantar-flexors, and walking ability by the test of timed "Up and Go" before treatment, weekly during the 3-week treatment, and 8 weeks after the onset of stroke. RESULTS: After 3 weeks of treatment, the percentage of CSS score of the FES group was 31% +/- 35%, significantly lower than those of the placebo and control groups (50% +/- 88% and 65% +/- 65% respectively, both P < 0.05); the ankle dorsiflexion torque of MIVC of the FES group was 9 Nm +/- 5 Nm, significantly higher than those of the placebo and control groups (5 Nm +/- 3 Nm and 4 Nm +/- 5 Nm respectively, both P < 0.05), and the electromyogram co-contraction ratio of the FES group was 8% +/- 5%, significantly lower than those of the placebo and control groups (27% +/- 26% and 28% +/- 19% respectively, both P < 0.05). The time needed to recover the walking ability after the stroke onset of the FES group was 18 +/- 8 days, shorter by 2 approximately 3 days than those of the placebo and control groups (20 +/- 7 and 21 +/- 8 days respectively). The percentage of the patients able to walk with the help of a stick 3 weeks after treatment of the FES group was 85%, significantly higher than those of the placebo and control groups (60% and 46% respectively, both P < 0.05). 84.6% of the patients of the FES group returned home, a percentage significantly higher than those of the placebo and control groups (53% and 46% respectively, both P < 0.05). CONCLUSION: FES, plus standard rehabilitation, is effective in improving the motor and walking ability of the patients with acute stroke, to the degree that most patients are recovered to be able to return home.