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This article discusses the relationship between strength training and leptin concentrations in men. An analysis of resting energy expenditure, hormone responses, and systemic circulation is presented.

During maximal exercise, cardiac output, or the volume of blood the heart pumps, may be 400 to 500 percent greater than that at rest. Recent studies have shown that increased stroke volume, the amount of blood pumped per beat, is an important factor in increasing cardiac output during exercise. Some studies have also indicated that the ways in which stroke volume is increased during exercise are not the same in men and women. To determine if there are gender differences in cardiac output during exercise, the stroke volume of normal, exercising men and women was evaluated. The subjects were matched by age and weight-adjusted peak oxygen consumption. (Stroke volume increases during exercise when left ventricular end-diastolic volume increases and left ventricular end-systolic volume decreases. This results in increased left ventricular ejection fraction, which is the percent of blood emptied from the left ventricle at the end of a contraction.) Stroke volume, left-ventricular end-diastolic and end-systolic volumes, cardiac output and left ventricular ejection fraction were measured in 27 women and 34 men who exercised to exhaustion on stationary bicycles. For women oxygen consumption was 20 percent lower at rest and 8 to 20 percent lower during exercise, compared with men. Women's heart rates were higher during exercise. There were no differences between the two groups in stroke volume index, left ventricular end-diastolic and end-systolic volume indexes, and left ventricular ejection fraction at rest or during exercise. Increases in the left ventricular end-diastolic volume during exercise were similar in both men and women; they accounted for most of the exercise-related increases in stroke volume. These results indicate that gender does not play an important role in increasing cardiac output during exercise. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Breathing during weight training and cardiovascular exercise is an important part to any routine, but too much concentration on it can be a hindrance. Three opinions on the importance of breathing during physical exercise are presented.