BelgiumSUMMARY Twelve cyclists and 12 long distance runners matched for age, height, and weight with two control groups of 12 non-athletes were studied echocardiographically to evaluate cardiac structure and function. Runners weighed 8 kg less than cyclists, but age and height were similar. Peak oxygen uptake per kg body weight was higher in athletes than in the control subjects but was similar in the cyclists and in the runners. The athletes' hearts had a larger end diastolic left ventricular internal diameter, mean wall thickness, and cross sectional area of the left ventricular wall than those of the respective control subjects. Nevertheless, whereas the left ventricular internal diameter was not different between the cyclists and runners, mean wall thickness and cross sectional area of the left ventricular wall were greater in the cyclists even after adjustment for weight. The ratio of wall thickness to left ventricular internal radius was significantly larger in cyclists than in their control group, but the ratio was similar in runners and their control group. The echocardiographic indices of left ventricular function were similar in the athletes and the control groups. Systolic left ventricular meridional wall stress was lower in the cyclists than in the runners.The data suggest that runners develop an increase in left ventricular wall thickness which is proportionate to the internal diameter but that in cyclists the increase is disproportionate because of the isometric work of the upper part of the body during cycling.Long distance cycling and running are two predominantly isotonic endurance sports. Cycling, however, comprises isometric work of the upper part of the body. Ultrasound imaging of the heart of athletes has shown that isotonic and isometric training lead to different adaptations of cardiac structure-that is, mainly left ventricular eccentric hypertrophy in the former'"-I and concentric hypertrophy in the latter. 1 7 9 11 Whether these adaptations of the heart also differ between long distance cyclists and runners has not often been studied. Only Snoeckx et al studied both types of athletes and found that calculated muscle mass was significantly greater in the cyclists.1' Furthermore, data on both groups of athletes suggest that the structural adaptations of the heart are moreRequests for reprints to Dr R Fagard, Laboratorium voor Hartfimctie, Inwendige Ziekten-Cardiologie, UZ Pellenberg, B-3041 Pellenberg, Begium.Accepted for publication 13 March 1984 pronounced in CyCliStS12 -4 than in runners. '-0 Cyclists, however, generally weigh more than runners, which could affect differences in cardiac structure between the two types of athletes.In the present study we assessed echocardiographically the cardiac structure and function of long distance cyclists and runners and of two groups of nonathletic control subjects matched for age, weight, and height for either the cyclists or the runners. Subjects and methodsTwelve male cyclists (aged 18-35 years) and 12 male runners (aged 19-40) were studied....
Plasma indicators of muscle cell leakage and of hemolysis were studied in 23 runners before and after a marathon race. Blood samples were drawn from an antecubital vein the morning before the race (baseline), at 3 p.m., i.e., 2 h before the start, on arrival, 12 and 36 h, and 7 days later. Compared with the baseline values, the plasma creatinine phosphokinase MM and MB subfractions, aldolase and glutamicoxaloacetic transaminase activity were increased immediately after the race, rose further 12 h after the marathon, and remained elevated the race, rose further 12 h after the marathon, and remained elevated 36 h and 7 days later. The plasma lactate dehydrogenase activity and myoglobin concentration were increased on arrival and returned to the pre-race activity 7 days after the marathon. Compared with the pre-race values, the plasma haptoglobin concentration was decreased immediately and 12 h after the marathon. Our data show that indicators of muscle cell leakage and of hemolysis in plasma, withdrawn after a marathon race, remained elevated for up to 7 days after the race.
Erythrocyte, plasma and urinary magnesium (Mg2+) concentration was measured in 23 runners before and after a marathon race. Blood samples were drawn from an antecubital vein the morning before the race (baseline), at 3 p.m. (2 h before the start), upon finishing and 12 h later. Compared with the baseline values, the intra-erythrocyte and plasma Mg2+ were decreased (p less than 0.05 or less) immediately after the marathon, from 2.13 +/- 0.16 to 2.02 +/- 0.18 mmol.l-1 cells and from 0.88 +/- 0.06 to 0.81 +/- 0.07 mmol.l-1 respectively. The Mg2+ concentration returned to pre-race values 12 h after completion of the marathon. The urinary Mg2+ excretion rate decreased (p less than 0.001) from 29 +/- 13 to 5 +/- 3 mumol.min-1 during the marathon and increased (p less than 0.05) 12 h after the race to 38 +/- 18 mumol.min-1. It is concluded that the reduction in plasma Mg2+ ion concentration during the marathon cannot be attributed to erythrocyte uptake, urinary excretion or loss in sweat. It is suggested that Mg2+ may be released from erythrocytes into the extracellular fluids during sustained exercise and taken up from these fluids by the adipose cells.
The chronic effect of training on intraerythrocyte cationic concentrations and on red cell Na+,K+-ATPase pump activity was studied by comparing well-trained athletes with sedentary subjects at rest. Also the acute effect of a 50-min cross-country run on these erythrocyte measurements was studied in the athletes. At rest the intraerythrocyte potassium concentration was increased (P less than 0.01) in the athletes compared to that of the control subjects. The intraerythrocyte concentrations of sodium and magnesium and red cell Na+,K+-ATPase pump activity were, however, similar in the trained and the untrained subjects. As compared with the resting condition, the intraerythrocyte potassium concentration was decreased (P less than 0.05) after exercise in the athletes, and this was accompanied by a minor increase in the intraerythrocyte sodium concentration. Red cell Na+,K+-ATPase pump activity was slightly increased (P less than 0.05) after exercise.
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