Cardiac Frequency During Submaximal Exercise in Young Adults; Relation to Lean Body Mass, Total Body Potassium and Amount of Leg Muscle

Abstract

The cardiac frequency and consumption of oxygen during submaximal exercise, lean body mass, total body potassium, thigh muscle width and an index of thigh muscle volume have been obtained for seventy-nine healthy men and women, ages 18 to 38 yrs, who were not in athletic training but accustomed to taking some exercise. For these subjects, at any specified submaximal rate of consumption of oxygen, the cardiac frequency is negatively correlated with the indices of body muscle which are themselves inter-correlated (r > 0.89). The latter relationships provide a basis for prediction of total body potassium (coefficient of variation 6f1 %).The relationship of exercise cardiac frequency to body muscle is similar in both men and women; it provides a better description of frequency than one based on consumption of oxygen alone (coefficient of variation respectively 12% and 18%). Cardiac frequency is independently related to the level of habitual activity of the subjects. The implications of these findings are discussed.Using data for young adults not in athletic training this paper examines the relationship of the cardiac frequency during submaximal exercise to indices of body muscle and shows that the two are related when allowance is also made for the consumption of oxygen. The basis for this relationship is set out below; the implications are considered in the discussion.The cardiac frequency and the cardiac output during submaximal exercise are linearly related to the consumption of oxygen; but whereas the former relationship is known to vary between subjects, the latter is relatively constant [Bevegard, Holmgren and Jonsson, 1963; Reeves, Groves, Blout and Filley, 1961]. The linearity of the two relationships implies that for an individual subject the cardiac stroke output is relatively independent of the rate of work; this is the case for exercise in both a supine and an upright posture, though for the latter the stroke output is larger during mild exercise than it is at rest [Bevegard et al., 1963]. The stroke output is the resultant of a number of factors of which one must be the muscularity of the heart. Since the cardiac output is the product of the stroke output and the frequency, the frequency at any level of cardiac output should also be related to the amount of muscle. The present study explores this relationship in groups of subjects by measuring

Effects of moderate exercise training on plasma volume, baroreceptor sensitivity and orthostatic tolerance in healthy subjects

“…1). From the regression equation we determined the heart rate at a standard vo, of 1.5 1 min-' (Cotes et al 1973) and following repeat testing, the significance of a shift in the line and a measure of a change in cardiorespiratory fitness was taken as a significant change in the elevation of the regression line (Kappagoda et al 1979). Peak vo, was the oxygen uptake at the highest stage of exercise that the subject could undertake.…”

“…Furthermore, the programme is relatively simple and considered to be safe. We used submaximal methods for assessing fitness partly also because of safety and acceptability (Cotes, 1993) and partly because of the better reproducibility (Mary, 1987).…”

Genome-wide linkage scan for submaximal exercise heart rate in the HERITAGE family study

“…Previous studies have shown associations between elevated heart rate (HR) at rest and increased risk of both all-cause and cardiovascular mortality (7,18,21,22,25,26,33). Although HR during submaximal exercise is known to decrease in response to regular endurance training (16,51), its recovery after maximal and submaximal exercise is considered a powerful predictor of mortality (14,15). However, interindividual differences in training-induced changes in HR are considerable.…”

The Repeatability of the Measurement of Aerobic Power in Man and Factors Affecting It

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