DEVELOPMENT OF A METHOD FOR PREVENTING ORTHOSTATIC HYPOTENSION DURING PROLONGED STATIC STANDING

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05680083
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 体育学
• Research Institution: SHIZUOKA UNIVERSITY
• Principal Investigator: INAMURA Kinsaku SHIZUOKA UNIV., FAC.OF LIBERAL ARTS,PROF., 教養部, 教授 (80022119)
• Co-Investigator(Kenkyū-buntansha): MANO Tadaaki NAGOYA UNIV., RESEARCH INST.OF ENVIRONMENTAL MED., PROF., 環境医学研究所, 教授 (30023659)
• Project Period (FY): 1993 – 1994
• Keywords: Countermeasure / Orthostatic hypotension / Prolonged static standing / Muscle pumping / Cardiac output / Postural sway

Research Abstract

To develop a method for preventing orthostatic hypotension using voluntary muscle contraction, 30 healthy young males aged from 18 to 23 years were required to maintain upright standing for 30 min. Front-back sway of foot pressure center (postural sway) by a platform stabilometry, and cardiac parameters by an impedance plethysmography were measured during the experiments. Control condition was static standing with as little movement as possible. Experimental conditions were (A) static standing with repetitive voluntary muscle contractions in the lower abdomen at the timing of a backward shift in postural sway, (B) standing with the repetitive muscle contractions in the middle abdomen at the timing of a backward shift, (C) standing with the repetitive muscle contractions in the calf and lower abdomen at the timing of a forward shift, and (D) standing with the repetitive muscle contractions in the calf at the timing of a forward shift and the contractions in the abdominal muscles at the timing of a backward shift. Results of the cardiac parameters for 20 min in the experimental conditions were compared with the ones in control condition.
In the condition (A), mean values of stroke volume in 43% of the subjects increased. The ones in 40% of the subjects increased in condition (B). The ones in 50% of the subjects increased in condition (C). The ones in the 62% of the subjects increased in condition (D). Increase ratio of stroke volume in these subjects in condition (D) was 10.1% . This increase was statistically significant (p<0.01). Increase ratio of cardiac output was 12.6%.
These results may signify that the voluntary muscle contraction in condition (D) is regarded as the most effective method for enhancing the muscle pumping. We concluded that the voluntary muscle contraction in the calf and abdomen synchronized with postural sway is expected to be useful as a countermeasure to orthostatic hypotension or syncope in prolonged static standing in humans.