P O Astrand’s research while affiliated with The Children's Hospital of Philadelphia and other places

To study central circulation at different levels of hemoglobin (Hb) concentration, five subjects performed submaximal and maximal exercise in three different situations: 1) control, 2) after venesection of 800 ml of whole blood, and 3) after reinfusion of the red blood cells about 30-35 days after venesection. Maximal oxygen uptake (VO2 max) decreased from 4.27 l-min-1) at control to 4.03 l-min-1 after venesection (P less than 0.05) and increased to 4.61 l-min-1 after reinfusion (P less than 0.05). Maximal values on cardiac output (Q), heart rate (HR), and stroke volume (SV) were the same in the three situations. Thus, there was no compensatory increase in Qmax due to the lowered arterial oxygen content (Cao2) after venesection. An increase of the Cao2 (Hb concentration) and a lowering of the Cvo2 contributed equally to the increased VO2 max after reinfusion. At a given submaximal VO2, HR and blood lactates were increased at lowered Hb concentration and decreased at increased Hb concentration over control levels. Correlation coefficient for the change in Q in relation to the acute change in Hb concentration at a given submaximal VO2 was -0.49 (P less than 0.05).

In 5 healthy male subjects performing submaximal and maximal work in swimming and running, respectively, V(O2), heart rate, and cardiac output (dye dilution technique) were measured. O2 saturation, O2 and CO2 content, O2 and CO2 tensions, and pH of arterial and venous blood were determined during one submaximal and maximal work load. At a given V(O2) submax during swimming and running the cardiac output, stroke volume, and heart rate were similar. On an average V(O2) max was 15% lower, maximal cardiac output 10% lower, and maximal stroke volume about the same in swimming compared with running. Mean arterial blood pressure was higher during swimming. Arterial O2 tension was slightly higher during submaximal and maximal swimming compared with running. Systemic avD(O2) during maximal work was lower in swimming, while the O2 extraction from circulating blood in exercising leg was the same compared with running. VE during maximal work averaged 111.0 and 154.2 1 x min-1 in swimming and running, respectively, while calculated alveolar ventilation averaged 101.8 in maximal swimming compared with 111.2 1 x min-1 in maximal running. Maximal values for blood lactate were similar in the 2 modes of exercise.

Three male swimmers underwent 10-min resting and 20-min swimming (breaststroke) exposures in a swimming flume. Water temperatures in separate exposures were 18, 26, and 33 C. At each water temperature the subjects rested and swam at water velocities of 0.50, 0.75, and 0.95 m/sec, which were designed to produce around 40, 70, and 100% of maximal aerobic power. Measurements were made of esophageal temperature, four skin temperatures, water temperature, heat flow from five local skin surfaces (Hatfield-Turner disks), and oxygen uptake. Calculations were made of mean area-weighted skin temperature and heat flow, metabolic rate, and heat storage. Internal body temperature changes after 20 min of swimming were related to water temperature, swimming intensity, and body composition.

Thirty five female and 31 male subjects performed submaximal and maximal exercise on a bicycle ergometer in 1949 (age 20-33 yr) and again in 1970. All had been well trained in 1949 and most had been physically active in the intervening years. In 1970 their maximal oxygen uptake had declined without exception by approx 20%, i.e. from 2.83 to 2.20 l/min for female subjects and from 4.08 to 3.28 l/min for male subjects. Their maximal heart rate had declined by 15 and 12 beats/min, respectively, with wide individual differences. In 1970 the average heart rate at a given submaximal oxygen uptake was significantly higher than in 1949, but due to marked individual variations in this heart rate response, the reduction in maximal O2 uptake could not be predicted from the repeated submaximal tests.

Three subjects with lowered internal body temperatures performed brief bouts of bicycle ergometer exercise at 150 and 200 W. Oxygen uptake during exercise was consistently greater than that required by the working muscles, the increase being the result of the additional cost of shivering. Increases in metabolism during exercise above control levels were inversely proportional to internal temperature (with skin temperature constant) below a given internal temperature threshold. Observations of intense shivering during exercise which is proportional to lowered internal temperature in the same manner as during rest provides further evidence against the concept of a decrease in the thermoregulatory set point during exercise in man.

The introduction is concerned specifically with a topical problem whose re-evaluation became necessary when more and more well-trained old men and women made their appearance in athletic contests: the problem of physical activity and aging. Only 20 years ago, a comprehensive study of structural and functional changes in men and women between 30 and 90 years of age was conducted by the National Institutes of Health of the U. S. The investigators described a consistent trend of decline over the years of the parameters: basal metabolic rate, work rate, cardiac output, vital capacity, maximum breathing capacity, nerve conduction velocity, body water content, filtration rate of kidney and kidney plasma flow.

The field of the physiology of training and performance is extremely heterogeneous. It becomes more and more difficult to be a “work physiologist” according to the classical concept. The research is now quite complicated and time consuming with regard to methods and detailed and profound knowledge. It covers so many different subjects as the physics and dynamics of air movement into and out of the lungs, the biochemistry on a cellular level, not to mention all the links between these fields and the oxygen transporting system — to mention one “homogeneous” concept. The field really demands specialists on isolated details, but there is then the inevitable risk that one gradually loses the ability and knowledge essential for an integration. Physical performance is a result of success in a coordinated function of all cells in the body.

In einer klugen und kenntnisreichen Abhandlung zur Begründung des Sportunterrichts findet sich, nachdem alles ordentlich behandelt worden ist, was man heute dazu sagen muß, am Ende folgender Satz: „Wenn man weit ginge, wäre sogar die Frage denkbar, ob Sport überhaupt sinnvoll ist.“

In a wise and knowledgeable dissertation on the justification for the teaching of sport we find at the end, after everything that need be said on the subject today has been properly dealt with, the following sentence: “If we were to proceed far enough, it is conceivable that we might pose the question whether sport is meaningful at all”.