Biomedical subjects

R C Reibold

Publications and source records attributed to R C Reibold.

4 recordsLinked to original sources

PubMed1990

Aerobic fitness norms for males and females aged 6 to 75 years: a review.

An extensive literature review was performed of studies where VO2max was measured directly in healthy, untrained subjects in the USA, Canada and 7 European countries to establish absolute (L/min) and relative (ml.kg-1.min-1) VO2max norms in males and females aged 6-75 years. Mean norms (L/min) in males show an increase from 1.0 L/min at age 6 years, to 2.0 and 3.4 L/min at ages 12 and 18 years, respectively, after which they decline with age to 3.2, 2.7, and 1.6 L/min for ages 30, 50, and 75 years, respectively. The corresponding values for females aged 6, 12, 18, 30, 50, and 75 years are 0.9, 1.8, 2.2, 1.8, and 1.1 L/min, respectively. Sex differences in relative VO2max are smaller than the above. Mean values for males for the above age groups are 47.5, 50, 48, 35, and 25 ml.kg-1.min-1, respectively, with corresponding values for females of 42.5, 44, 41, 28, and 17.5 ml.kg-1.min-1, respectively. These norms (L/min) are slightly lower than Robinson's 1938 data on males; they are only 1.5% lower compared with Astrand's adult males norms; but 2.5 to 10% lower than Astrand's norms for adult females. Present norms (ml.kg-1.min-1) for middle aged and older women are 25% lower than the corresponding Astrand's norms.

Adolescent↗

PubMed1983

Hemodynamic responses during prolonged sitting.

Eight young men (group A) underwent 5 h of quiet sitting, preceded by 30 min of recumbency, 20 min of standing, and 20 s of walking, and five other young men (group B) underwent 70 min of sitting, preceded by recumbency only, to determine the effects of prolonged sitting and previous posture on hemodynamic responses (measured by impedance plethysmography). Group A showed more calf blood pooling and a decrease in thigh blood flow during sitting in comparison with the control group, but after 1 h of sitting hemodynamic responses of the two groups were similar. Sitting for 5 h (1st vs. 5th h) resulted in an increase in calf venous pooling (17%) and a decrease in calf BF (13%), a reduction in gravitational pooling in the thigh (corresponding to increased pooling in the calf), increases in diastolic and mean arterial pressures (6 and 7.3 mmHg, respectively), and minor changes in heart rate, stroke volume, and cardiac output. The results show that it is necessary to sit for 1 h before hemodynamic responses can be assessed in this position, regardless of the posture maintained previously. The main effect of prolonged sitting is pooling in the calf, which is compensated for by an increase in peripheral resistance.

Adult↗

PubMed1982

Effect of the circutone seat on hemodynamic, subjective, and thermal responses to prolonged sitting.

Eight young men were twice administered--on two different days--a series of hemodynamic (using an impedance plethysmograph), subjective, and skin temperature measurements during 5 h of quite sitting. On one day, a Circutone seat (massage-type seat cushion) was activated for 14 min/h, and on the other day it was not. During the "Circutone off" day, 5 h of sitting resulted in a continuous decrease in calf blood flow and an increase in venous blood pooling in the calf; an increase in blood pressure and a stable cardiac output (4.6 l/min); very low urine output; large increases in skin temperatures at the body areas in contact with the seat (thigh and lower back); and increases in various subjective responses of discomfort. The Curcutone activation resulted in a substantial exchange of the stagnant blood in the calf and thigh; a tendency to increase thigh and calf blood flow; a decrease in venous pooling in the thigh; and less subjective discomfort. The Circutone activation had no effect on skin temperature. The results indicate that the Circutone seat improved seat comfort by improving local circulation, especially in the thigh, which probably accounted for the improved subjective reactions.

Blood Circulation↗

PubMed1982

Hemodynamic responses in orthostasis following 5 hours of sitting.

Six young men were administered an orthostatic test, 20 min of quiet standing before and after 5 h of quiet sitting, to determine the effect of sitting fatigue on orthostatic responses. Hemodynamic responses were recorded with an impedance plethysmograph. During the 5 h sitting period, there was a 15.6% decrease in calf blood flow, a 19.4% increase in venous pooling in the calf, and an increase in blood pressure. A comparison between the two standing tests showed increases in blood pressure and in total peripheral resistance, decreases in heart rate (7 beats/min), cardiac output (12.7%) and calf blood flow (18.5%), and 70% increase in calf venous pooling after sitting. The results show that prolonged sitting constitutes a mild orthostatic stress where an increase in venous pooling is compensated by an increase in blood pressure. When this is followed by standing, insufficient compensations are made to the large amounts of pooling resulting from both postures. Despite the maintenance of a stable blood pressure (same as at the end of the sitting period) there is an insufficient increase in total peripheral resistance and heart rate resulting in a relatively low cardiac output. Thus, prolonged sitting constitutes a liability for subsequent performance in an upright position unless methods to minimize venous pooling are employed.

Adult↗