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Biomedical subjects

D B Dill

Publications and source records attributed to D B Dill.

At least 37 records · Page 2Linked to original sources
PubMed1976

Physiological adjustments of young men to five-hour desert walks.

Seven young men undertook a desert walk of 30 km at a rate of 100 m/min. Six finished; the seventh stopped after 24 km. Each satisfied his thirst with cool tap water each hour. Periodic observations included metabolic rate, blood pressure, heart rate, rectal and skin temperature, body weight, and volume of water drunk. Hand sweat was collected each hour and body sweat residues on the skin were collected at the end of the walk. Subjective reports revealed portents of breakdown: aching muscles, painful joints, hot or blistered feet, hunger, and boredom. Cardiovascular adjustment and temperature regulation maintained tolerable conditions. The volumes of water evaporated by the 5-h walkers were about the same. Wet bulb temperatures were below 25 degrees C; all sweat evaporated and was available for temperature regulation. The volume of water drawn from body reserves was closely correlated with concentration of chloride in body sweat; the volume of water that satisfied thirst maintained osmotic pressure.

Adolescent↗
PubMed1976

Physiological aging of champion runners.

The physiological adjustments to aerobic work (5.6 km/h, up a 9% grade) and to exhausting treadmill work of former champion middle-distance runners were determined in 1971, at ages 47-68 yr, 25-43 yr after their competitive careers in track. In the resting state the former athletes as a group are very much like nonathletes of the same ages. Efficiency in the aerobic walk was the same in both groups and did not change with age in either, but the former athletes on the average performed the walk with less strain as indicated by lower blood lactates, "ventilatory equivalents," and heart rates than nonathletes at corresponding ages. Mean VO2max of the runners declined from 71.4 ml/min-kg-1 in youth to 41.8 at a mean age of 56.6 yr, as compared with mean values of 50.6 and 36.5 ml/min-kg-1 in nonathletes at corresponding ages. VO2max had declined below the average of nonathletic men in only two of the former runners. Mean maximal heart rate declined with age from 186 to 180 in the runners, and from 199 to 186 in nonathletes at corresponding ages. Ventilatory responses of men in both groups were closely related to the increases of blood lactate in both aerobic and maximal work.

Aged↗
PubMed1975

Longitudinal studies of aging in 37 men.

The physiological adjustments of the men to both aerobic (5.6 km/h, up 9% grade), and maximal treadmill work were first determined when they were healthy college students, ages 18-22 yr. They were restudied at ages 40-44, and again at ages 49-53 yr. In the aerobic walk VO2 increased in proportion to weight gain, but efficiency did not change with age. The men who had gained most weight showed the greatest elevations of heart rate, blood lactate and "ventilatory equivalent," and reductions of the "O2 pulse" in the walk. At age 50 mean "O2 pulse" in exhausting work had declined 13%, even though mean maximal heart rate had declined 15 beats/min from values observed in youth. At ages 40-44 yr mean VO2 max had declined 25% to values 12% lower than mean values reported in 1938 for men of this age. Eight of the men imporved an average of 11% in VO2 max between ages 40-44 and 49-53 yr; mean VO2 max of the others continued to decline with age. The five men who improved most had increased their participation in vigorous activities (tennis, squash, skiing, jogging, etc.) and had quit or reduced their smoking.

Adolescent↗
PubMed1975

Effects of equivalent sea-level and altitude training on VO2max and running performance.

Twelve middle-distance runners, each having recently completed a competitive track season, were divided into two groups matched for maximal oxygen uptake (VO2max), 2-mile run time and age. Group 1 trained for 3 wk at Davis, PB = 760 mmHg, running 19.3 km/day at 75% of sea-level (SL) VO2max, while group 2 trained an equivalent distance at the same relative intensity at the US Air Force Academy (AFA), PB = 586 mmHg. The groups then exchanged sites and followed a training program of similar intensity to the group preceding it for an additional 3 wk. Periodic near exhaustive VO2max treadmill tests and 2-mile competitive time trials were completed. Initial 2-mile times at the AFA were 7.2% slower than SL control. Both groups demonstrated improved performance in the second trial at the AFA (chi = 2.0%), but mean postaltitude performance was unchanged from SL control. VO2max at the AFA was reduced initially 17.4% from SL control, but increased 2.6% after 20 days. However, postaltitude VO2max was 2.8% below SL control. It is concluded that there is no potentiating effect of hard endurance training at 2,300-m over equivalently severe SL training on SL VO2max or 2-mile performance time in already well conditioned middle-distance runners.

Adolescent↗