6/25　勉強会

予演会

17th Annual Congress of the European College of Sport Science

4-7 July, Bruges – Belgium

担当；佐藤

THE EFFECT OF WATER IMMERSION ON SHORT AND LONG AFFERENT INHIBITION, SHORT INTRA CORTICAL INHIBITION AND INTRA CORTICAL FACILITATION IN HUMAN.

Sato, D.1, Yamashiro, K.1, Yoshida, T.2, Onishi, H.1, Shimoyama, Y.2, Maruyama, A.1
1: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, 2: Department of Health and Sports, Niigata University of Health and Welfare

Introduction

Water immersion can alter numerous physiological parameters depending on physical characteristics like buoyancy, hydrostatic pressure, and temperature. We have examined the effects of water immersion on cerebral cortical activities, and proposed that water immersion influences the cortical processing of somatosensory inputs (Sato et al., 2012). This result might imply that water immersion affect the sensorimotor processing. Therefore, the aim of the present study was to investigate the effect of water immersion on short and long afferent inhibition (SAI and LAI), short intra cortical inhibition and intra cortical facilitation (SICI and ICF).

Methods

Motor evoked potentials (MEPs), SAI, LAI, SICI and ICF were measured for seven healthy males at rest before, during and after the 15-minute water immersion. SAI and LAI were evaluated by transcranial magnetic stimulation (TMS) protocol based on coupling peripheral nerve stimulus with TMS of the motor cortex. MEPs induced with TMS were conditioned by painless electrical stimuli applied to right median nerve at interstimulus intervals (ISIs) of 20 and 200ms. The intensity of the stimulus was fixed at about three times the sensory threshold. SICI and ICF were tested using the paired-pulse TMS paradigm. MEP was recorded from first dorsal interosseous (FDI) muscle. The water level was allowed to reach the axillary level, and during the experiment, room and water temperatures were maintained at 30°C.

Results

SAI and LAI were reduced during water immersion (101.4±12.9% and 64.4±10.1%) compared with before and after water immersion (before: 67.5±9.7% and 41.2±14.9%, after: 63.4±10.0% and 40.4±13.1%). SICI and ICF were not significantly different among three conditions (before, during and after water immersion).

Discussion

Water immersion decrease short and long afferent inhibition in human. Tamburin et al. (2001) have suggested that increased sensory receptive field might induce summation of the SAI due to ‘centripetal gating’ mechanism or a ‘floor effect’. Our previous research have clarified that water immersion to the axillary level has a centripetal gating effect on short-latency somatosensory evoked potentials (SEPs) (Sato et al. , 2012) and increases the amplitudes of long-latency SEPs. Therefore, the present data suggested that the change in sensory input induced decreasing SAI and LAI during water immersion.

References

Tamburin S, Manganotti P, Zanette G, Fiaschi A. (2001). Exp Brain Res, 141, 232-41.

Sato D, Yamashiro K, Onishi H, Shimoyama Y, Yoshida T, Maruyama A. (2012). BMC Neurosci, 13, 13.

 

担当；山代

Shortening of long-latency somatosensory evoked potentials in baseball players

Koya Yamashiro 1,2, Daisuke Sato1,2, Hideaki Onishi1,3, Atsuo Maruyama1,2

1Institute for Human Movement and Medical Sciences, Niigata 950-3198, Japan

2Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan;

3Department of Physical Therapy, Niigata University of Health and Welfare, Niigata 950-3198, Japan

Introduction

We investigated the neuro-plastic changes in baseball player using long-latency somatosensory evoked potentials (SEPs). In general, long-term training of athletes and musicians is known to induce neuro-plastic changes. The aim of this study is to clarify whether the long-term training affect the long-latency SEPs relating to information processing of stimulation in baseball players.

Methods

SEPs were recorded from two groups (baseball group and sports group) in fifteen subjects at Fz, Cz, Pz, C3, C4 stimulating index finger of right hand. The intensity of the stimulus was three times the sensory threshold, and was never reported as painful. The inter-trial interval was randomized between 5-8 s. In baseball group, seven subjects have played baseball over 7 years. While, other subjects have played various sports such as swimming, track and field and soccer. Long-latency SEPs were measured under passive (control) condition and reaction time condition (movement condition). In the passive condition, subjects relaxed and had no task. In the reaction time condition, they were instructed to prepare to push the button, and to push it as fast as they could when the stimulus was presented.

Results

P100 and N140 were elicited by two groups and conditions. The latency of P100 and N140 in baseball group was significantly shorter than in sports group. In addition, reaction time in baseball group was significantly shorter than in sports group. Moreover, the latency of P100 and reaction time were significantly positive correlation.

Discussions

Sensation of hands is more important for baseball player than for runner, swimmer and soccer player. Baseball players need sensation of hands in various situations such as throwing, batting and catching. Therefore, long-term training may induce neuro-plastic changes in hand area, and this phenomenon may play an important role to quick responses to required movements.

担当；椿

Effect of hemodynamic changes caused by Valsalva maneuver on brain near-infrared spectroscopy measurements

Tsubaki, A.1, 2, Furusawa, A, A.2, Kojima, S.1, 3, Onishi, H.1, 2

1: Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, 2: Department of Physical Therapy, Niigata University of Health and Welfare, 3: Graduate school of Health and Welfare, Niigata University of Health and Welfare

Introduction

Near-infrared spectroscopy (NIRS) is widely used to measure human brain activation on the basis of cerebral hemodynamic response. The advantage of NIRS over other methods is that it provides direct, real-time measurement of oxygenation in cortical tissue. However, a limitation of NIRS is that hemodynamic changes influence the measured signals. The purpose of this study was to clarify the relationship between NIRS signals and blood pressure during the Valsalva maneuver.

Methods

Four healthy volunteers participated in this study. All participants provided written informed consent after experimental procedures had been explained. The study was approved by the Ethics Committee of Niigata University of Health and Welfare (17157-100203). Subjects performed a 20-s Valsalva maneuver to change blood pressure. NIRS (OMM-3000, Shimadzu) optodes were set in a holder at a distance of 30 mm and stabilized by a crepe bandage around the head. Changes in oxyhemoglobin (O2Hb) concentration were calculated by using the modified Beer–Lambert law. Thirty-four channels with an inter-optode distance of 30 mm were used for deep-penetration measurements (deepO2Hb), and nine channels with an inter-optode distance of 15 mm were used for shallow-penetration measurements (shallowO2Hb). The difference value (diffO2Hb) of deepO2Hb and shallowO2Hb was calculated. Beat-to-beat mean arterial pressure (MAP) was recorded by volume clamping the finger pulse with a Finometer (Finapres Medical Systems BV) on the left side. A height reference sensor was used to remove confounds related to arm position. Skin blood flow changes were measured at the forehead by a laser Doppler blood flow meter (Omegaflow FLO-CI, Omegawave, Inc). The relationships between deepO2Hb, shallowO2Hb, diffO2Hb, and MAP were assessed using Pearson’s correlation coefficient with significance set at P<0.05.

Results

Pearson’s correlation coefficient between deepO2Hb and MAP, shallowO2Hb and MAP, and diffO2Hb and MAP was 0.64–0.88 (P<0.01), 0.64–0.89 (P<0.01), and 0.45–0.67 (P<0.01), respectively.

Discussion

Regional and systemic changes in the cardiovascular state strongly influence NIRS signals. Our observations, which revealed a significant relationship between O2Hb and MAP, demonstrate that not only are blood pressure changes influenced by deep and shallow-penetration NIRS signals, but also that diffO2Hb is suitable for measuring brain activation.