Suppression of activation of muscle sympathetic nerve during non-noxious local cooling after the end of local cooling in normal adults.

PURPOSE: While non-noxious local cooling is widely used in physical medicine, its effect on muscle sympathetic nerve activity (MSNA) and cardiovascular regulation are not clear. The purpose of the present study was to assess the responses of MSNA, blood pressure (BP), heart rate (HR) and local blood flow during non-noxious local cooling. METHODS: The study included two protocols. Both protocols consisted of 10-min rest in supine position, followed by 15-min local cooling (15 °C) of the shin and anterior foot, and 20-min recovery. MSNA of the right common peroneal nerve, BP, HR, and shin skin temperature (TSK) were recorded in eight men in the first protocol, while leg blood flow (LBF) was measured in the same subjects by strain-gauge plethysmography in the second protocol. RESULTS: TSK gradually decreased from 31.5 ± 0.02 to 16.0 ± 1.01 °C (mean ± SEM) during local cooling, and gradually increased after the end of local cooling. No subject complained of pain, and BP and HR remained constant. The MSNA burst rate increased significantly (p < 0.05) to 141.1 ± 12.5 % during local cooling, but decreased significantly (p < 0.05) to 73.6 ± 5.9 % during the recovery period. Total MSNA also increased to 148.0 ± 14.2 % (p < 0.05) during local cooling, and decreased to 74.0 ± 13.9 % (p < 0.05) at recovery. LBF remained constant through the experiment. CONCLUSIONS: The results suggest that MSNA is activated by non-noxious local cooling, and attenuated after the end of local cooling without any changes in HR and BP.

Wheelchair marathon creates a systemic anti-inflammatory environment in persons with spinal cord injury.

OBJECTIVE: To investigate interleukin (IL)-6 and other inflammation markers in athletes with spinal cord injury (SCI) during a wheelchair marathon race. DESIGN: Nonrandomized study in an actual race. SETTING: The 28th Oita International Wheelchair Marathon Race, Japan. PARTICIPANTS: Twenty-eight men with SCI between T7 and L2 (16 full-marathon racers, full-group; and 12 half-marathon racers, half-group). MAIN OUTCOME MEASURES: Plasma IL-6, tumor necrosis factor (TNF)-α, and high-sensitivity C-reactive protein (hsCRP) were measured the day before, immediately after the race, and 2 hours after the race. RESULTS: Plasma IL-6 concentrations increased by 18.4-fold and by 9.4-fold (P < 0.05) in the full- and half-groups immediately after the race (P < 0.05), respectively, but returned to baseline at 2 hours of recovery. In contrast, plasma TNF-α and hsCRP did not change throughout the race in both groups. The fold change in plasma IL-6 immediately after the race relative to the prerace was significantly higher in the full-group than the half-group (P < 0.05). In both groups, plasma IL-6 immediately after the race did not correlate with the average wheelchair speed. Interestingly, plasma IL-6 and hsCRP before the race in the full-group, but not in half-group, correlated negatively with the average wheelchair speed (P < 0.05). CONCLUSIONS: The study demonstrated that half- and full-marathon wheelchair races increased plasma IL-6, but not TNF-α and hsCRP. Furthermore, the top athletes of the full-group had low plasma IL-6 and hsCRP at baseline. Wheelchair marathon competition, especially full-marathon, and daily training seem to have beneficial effects on SCI through the plasma IL-6 response.

Local heat application to the leg reduces muscle sympathetic nerve activity in human.

The study was designed to assess the effects of local heat (LH) application on postganglionic muscle sympathetic nerve activity (MSNA) measured by microneurography in healthy men. In the first protocol, MSNA of the left peroneal nerve, blood pressure (BP), heart rate (HR), and skin temperature of the shin (TSK) were recorded in nine men. In the second protocol, leg blood flow (LBF) was measured in the same subjects by strain-gauge plethysmography. In both protocols, after 10 min of rest in the supine position, a heated hydrocollator pack was applied to the shin and anterior foot for 15 min and recovery was monitored over a period of 20 min. TSK gradually increased from 31.7 ± 0.1 to 41.9 ± 0.5°C (mean ± SEM) during LH. No subject complained of pain, and BP and HR remained constant. The MSNA burst rate (16.1 ± 2.1 beats/min) during the control period decreased significantly (P < 0.05) to 72.0 ± 2.3% during LH. Total MSNA also decreased to 59.2 ± 2.6% (P < 0.05) during LH, but both immediately returned to baseline at recovery. In contrast, LBF in the left leg significantly and immediately increased (P < 0.05) after LH application and remained significantly elevated until the end of the recovery period. These results suggest that: (1) LH application significantly attenuates MSNA without any changes in HR and BP. (2) Other factors in addition to MSNA seem to control regional blood flow in the lower extremity during LH.

Standing position improves arm and hand performance on un-affected side in hemiplegic patients.

BACKGROUND AND PURPOSE: The main objective of this study was to compare the hand and finger performance of stroke patients in standing and sitting positions. METHODS: The study subjects were 11 males and 3 females with history of stroke (age, 68.6 ± 6.3 years, mean ± SD). Inclusion criteria were right-handedness before stroke, right hemiparesis due to left hemisphere lesion induced by stroke, at least 4 months between stroke and study enrollment, and ability to stand for more than 10 minutes. Tests of dexterity (peg board test), attention, unilateral spatial neglect, and cognition were conducted in comfortable sitting and standing positions. Seven subjects started in standing position, and the other seven subjects were tested first in sitting position. Tests in the first position were performed on one day, and repeated one week later but performed in a different position. RESULTS: The mean performance time on the peg board test in standing position was significantly faster than in sitting position (p=0.022). However, the results of the Trail making test-part A, line cancellation test, line bisection and Mini Mental State conducted in standing position were similar to those of sitting position. There were no differences between the first and second trial tests. CONCLUSIONS: Our results showed that standing position improved the functional performance of hand and arm on the un-affected side in stroke patients, but had no effects on consistent attention, unilateral spatial neglect, or cognition.