2706 km cycling in 2 weeks: effects on cardiac function in 6 elderly male athletes

Objectives: Physiological effects of exercise on trained and untrained individuals have been studied extensively. Typically, young or middle-aged individuals are examined before and after short periods of vigorous exertion. Methods: Westudied 6 elderlymale athletes (61 +/- 8 years (mean +/- SD); baseline (V)over dotO(2)max 48 +/- 5ml.kg(-1).min(-1)) with focus on cardiac function and biomarkers following 14 consecutive days of moderate intensity exercise. Cardiac dimensions, function, biomarkers, and other measures of cardiovascular health were examined at baseline and 2 and 28 h after the last day of cycling a total of 2706 km. Results: Data collected after the cessation of exercise on the 14th day revealed significant increases in average size of the left atrium (3.5 +/- 0.4 to 4.0 +/- 0.3 cm; p = 0.02) and left ventricular end systolic volume (47 +/- 2 to 52 +/- 5 ml; p = 0.004), with no other significant changes in cardiac size or function. Small, transient increases in cardiac biomarkers (troponin T, creatine kinase myocardial band, and N-terminal pro-brain natriuretic peptide) (p < 0.01) were observed 2 h after completion of cycling but no changes in systolic (including strain-analyses) or diastolic cardiac function were observed at rest. (V)over dotO(2)max was significantly lower at the 28 h time point than at baseline (p < 0.02). Plasma concentrations of total-(p < 0.01) and low-density lipoprotein-cholesterol (p < 0.01) were markedly lower after exercise. Systolic blood pressure was unchanged, but diastolic pressure was significantly lower after exercise than at baseline. Conclusions: The results suggest that repeated moderate intensity exercise in elderly men was associated with a transient increase in cardiac biomarkers while cardiac function remained unaltered. A favorable reduction in blood lipids and diastolic blood pressure were seen for > 28 h after the end of activity. An unexplained symptomless severe plasma hyponatremia developed in 3 of 6 subjects 28 h after the end of activity.