The endurance athletes heart: acute stress and chronic adaptation.

The impact of endurance exercise training on the heart has received significant research and clinical attention for well over a century. Despite this, many issues remain controversial and clinical interpretation can be complex of biomarkers of cardiomyocyte insult. This review assesses the current state of knowledge related to two areas of research where problems with clinical decision making may arise: (1) the impact of chronic endurance exercise training on cardiac structure, function and electrical activity to the point where the athletic heart phenotype may be similar to the expression of some cardiac pathologies (a diagnostic dilemma referred to as the 'grey-zone') and (2) the impact of acute bouts of prolonged exercise on cardiac function and the presentation of biomarkers and cardiomyocyte insult in the circulatory system. The combination of acute endurance exercise stress on the heart and prolonged periods of training are considered together in the final section.

Arterial compression during overhead throwing: a risk for arterial injury?

Case studies reporting aneurysm formation in the axillary artery have been described in overhead throwing athletes, possibly due to repetitive arterial compression by the humeral head that has been transiently observed during sonographic diagnostic arm manoeuvres. Whether compression negatively alters arterial health has not been investigated and was the focus of this study. The throwing arm of elite overhead athletes was screened for inducible axillary artery compression. Compressors (COMP, n = 11, mean age: 20 (SD: 2) year, 7 male, 4 female) were age and sex matched with noncompressing (NONCOMP) athlete controls. Four indices of arterial health (flow mediated dilation [FMD], conduit artery vasodilatory capacity [CADC], glyceryl-trinitrate [GTN]-induced vasodilation and intima-media thickness [IMT]) were assessed with high-resolution ultrasound at the brachial and the axillary, artery. No significant between-group differences were observed at the brachial, or axillary, artery for FMD (brachial: COMP: mean (SD) 6.2 (3.1)%, NONCOMP: 6.1 (3.5)%, p = 0.967, axillary: COMP: 8.0 (5.5)%, NONCOMP: 9.0 (3.6)%, p = 0.602), CADC (brachial: COMP: 10.4 (3.4)%, NONCOMP: 10.4 (5.4)%, p = 0.999, axillary: COMP: 9.6 (4.2)%, NONCOMP: 8.5 (3.2)%, p = 0.492), GTN-induced vasodilation (brachial: COMP: 17.9 (5.1)%, NONCOMP:14.1 (7.2)%, p = 0.173, axillary: COMP: 9.5 (4.3)%, NONCOMP: 7.7 (3.1)%, p = 0.302) or IMT (brachial: p = 0.084, axillary: p = 0.581). These results suggest that transient arterial compression, observed during diagnostic arm manoeuvres in overhead throwing athletes, is not associated with abnormal indices of artery function or structure and that other mechanisms must be responsible for the published cases of aneurysm formation in elite athletes performing overhead throwing actions.