CARDIORESPIRATORY CHANGES WHEN BALANCING ONES WHOLE-BODY ON ONE LEG WITH EYES CLOSED

Postural control system has been extensively studied in terms of somat ic motor function, but little is known about its connection with human autonomic function. The purpose of this study was to determine the ca rdiorespiratory changes in response to the 3-min load that was perform ed by balancing one's whole body on one leg with eyes closed (SOLEC lo ad) or eyes open (SOLEO load) in 11 healthy young subjects (5 males an d 6 females, mean age 20.8+/-1.9 year). Blood pressure (BP), heart rat e (HR), respiratory rate (RR), inspiratory and expiratory duration (T- i and T-e), tidal volume (VT), and oxygen uptake (V-O2) were measured before, during, and after the load. The SOLEC load produced significan t increases in HR and systolic BP within 1 min. There were further inc reases in systolic and diastolic BP during the late period of the load . Metabolic rate (V-O2) showed a gradual increase during the SOLEC loa d, indicating that the late responses would be partly due to metabolic alteration, The early responses are considered to be mediated neurall y through the postural control system which receives the afferent inpu ts arising from vestibular system and from muscle proprioceptors of th e leg. In contrast, SOLEO load caused small insignificant changes in B P, HR, VT, and V-O2 suggesting that a visual input is essential for ba lancing a postural change. The balance test with eyes closed may have value in a clinical neurological rehabilitation setting.