Shvartz E
Rockwell Aerospace, Space Systems Division, Product Assurance Engineering, Downey, CA 90241, USA.
Aviat Space Environ Med. 1996 Oct;67(10):935-9.
Several lower body negative pressure studies conducted in recent years have suggested that aerobically fit individuals have poo-orthostatic tolerance (OT).
There will be significant differences between OT of highly fit endurance runners and unfit individuals.
Subjects were 17 men and 17 women aged 29-42 yr who were administered two orthostatic tests (20 min standing) before, and 5 min following a VO2max test. There were 6 men and 6 women who were highly trained endurance runners with VO2max of 63 and 50 ml.kg-1.min-1 for the men and women, respectively; 6 men and 6 women had average fitness (VO2max of 40 and 32 ml.kg-1.min-1, respectively), and the remaining 5 men and 6 women had poor fitness (VO2max of 32 and 26 ml.kg-1.min-1, respectively).
The trained men and women showed good OT before and after exercise, which was characterized by very low orthostatic heart rates (54 and 64 bpm before, 70 and 75 bpm after exercise, for the men and women, respectively); relatively large pulse pressures (PP); and a lack of any adverse subjective reactions. The untrained subjects' orthostatic heart rates were 30-40 bpm higher than in the trained subjects, (18 bpm higher after, vs. before exercise) their PP was narrower, and there were 7 cases of orthostatic weakness (dizziness, yawning) and 8 fainting episodes. (6 cases before, 9 cases after exercise).
Aerobically fit individuals have good OT while unfit individuals show poor OT. Since the maintenance of good OT is important in the Space Shuttle flights, endurance training enhances crew/vehicle safety.
近年来进行的多项下体负压研究表明，有氧适能个体具有较差的立位耐力（OT）。
高度适能的耐力跑者与不适能个体的OT之间存在显著差异。
受试者为17名年龄在29 - 42岁之间的男性和17名女性，在进行最大摄氧量（VO2max）测试前和测试后5分钟分别接受两次立位测试（站立20分钟）。其中有6名男性和6名女性是经过高度训练的耐力跑者，男性和女性的VO2max分别为63和50 ml·kg⁻¹·min⁻¹；6名男性和6名女性有氧适能一般（VO2max分别为40和32 ml·kg⁻¹·min⁻¹），其余5名男性和6名女性有氧适能较差（VO2max分别为32和26 ml·kg⁻¹·min⁻¹）。
经过训练的男性和女性在运动前后均表现出良好的OT，其特征为立位心率非常低（男性运动前和运动后分别为54和70次/分钟，女性分别为64和75次/分钟）；脉压（PP）相对较大；且没有任何不良主观反应。未经训练的受试者立位心率比经过训练的受试者高30 - 40次/分钟（运动后比运动前高18次/分钟），其PP较窄，有7例出现立位无力（头晕、打哈欠），8例昏厥发作（运动前6例，运动后9例）。
有氧适能个体具有良好的OT，而不适能个体的OT较差。由于在航天飞机飞行中维持良好的OT很重要，耐力训练可提高机组人员/飞行器的安全性。
