Antigravity Effects of Leg Exercise

Rosenhamer, G.

doi:10.1111/j.1365-201x.1968.tb10813.x

Cited by 3 publications

References 10 publications

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Gas Exchange Under Altered Gravitational Stress

Prisk¹

2011

Comprehensive Physiology

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Efficient gas exchange in the lung depends on the matching of ventilation and perfusion. However, the human lung is a readily deformable structure and as a result gravitational stresses generate gradients in both ventilation and perfusion. Nevertheless, the lung is capable of withstanding considerable change in the applied gravitational load before pulmonary gas exchange becomes impaired. The postural changes that are part of the everyday existence for most bipedal species are well tolerated, as is the removal of gravity (weightlessness). Increases in the applied gravitational load result only in a large impairment in pulmonary gas exchange above approximately three times that on the ground, at which point the matching of ventilation to perfusion is so impaired that efficient gas exchange is no longer possible. Much of the tolerance of the lung to alterations in gravitation stress comes from the fact that ventilation and perfusion are inextricably coupled. Deformations in the lung that alter ventilation necessarily alter perfusion, thus maintaining a degree of matching and minimizing the disruption in ventilation to perfusion ratio and thus gas exchange.

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Gas Exchange Under Altered Gravitational Stress

Prisk¹

2011

Comprehensive Physiology

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Exercise and Arterial Pressure during Simulated Increase of Gravity

Linnarsson

Rosenhamer

1968

Acta Physiologica Scandinavica

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Heart rate and arterial pressure were continuously recorded in eight healthy young adults in the sitting position at 3 G, acting in the head‐seat direction, before and during leg exercise at 600 kpm/min for 6 min. In spite of the threefold increase of the hydrostatic pressure gradient along the head‐trunk line the arterial mean pressure at the level of the heart was higher at 3 G than at normal gravity, both at rest and during exercise. Exercise at 3 G resulted in a more rapid rise in the arterial mean and pulse pressures, the final increments being similar or somewhat greater than they were at normal gravity. The results emphasize the importance of the leg muscle pump as a booster of the cardiac pump in situations where large hydrostatic pressures in the lower portion of the body would otherwise tend to curtail the effective circulating blood volume.

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Acceleration Stress and Effects of Propranolol on Cardiovascular Responses

Bjurstedt

Rosenhamer

Tydén

1974

Acta Physiologica Scandinavica

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BJURSTEDT, H., G. ROSENHAMER and G. T Y D~N .Acceleration stress and effects of propranolol on cardiovascular responses. Acta physiol. scand. 1974. 90. 491- 500.Heart rate, arterial pressure and cardiac output were recorded in six physically well-trained, young male volunteers in the sitting position at normal gravity and at 3 G acting in the head-seat direction, before and after beta-adrenergic blockade by propranolol. Studies were performed both at rest and during leg exercise a t a load corresponding to 50 70 of the maximal oxygen uptake. After propranolol, the heart rate response to increased G at rest averaged 38 ' % of that observed without blockade, indicating that G-induced cardioacceleration is predominantly due to sympathetic stimulation. G-induced decline of cardiac output was more marked after propranolol, this effect being entirely due to the reduced response of the heart rate. In spite of the cardioinhibitory effects of propranolol, subjective G tolerance was well preserved; the response of the arterial mean pressure to increased G was unaffected due to a 65 7% rise in systemic vascular resistance as against 43 % before propranolol. Hence, sympathetic chronotropic stimulation of the heart is not essential for the circulatory defense against increased gravitational stress. Transition from rest to exercise at 3 G produced a larger increase in stroke volume than in heart rate; after beta-adrenergic blockade the dominance of the stroke xolume increase was exaggerated. 24 74 179 1.92 54 S.B. 32 70 176 1.85 54 J.P. 24 63 173 1.75 47 R.H. 21 78 178 1.96 50 M.S. 20 73 185 1.95 48 B.S.A. = body surface area from nomogram of Dubois and Dubois (1916), Volmax = maximal oxygen uptake

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Antigravity Effects of Leg Exercise

Cited by 3 publications

References 10 publications

Gas Exchange Under Altered Gravitational Stress

Gas Exchange Under Altered Gravitational Stress

Exercise and Arterial Pressure during Simulated Increase of Gravity

Acceleration Stress and Effects of Propranolol on Cardiovascular Responses

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