Application of the Heart Score Concept to the Electrocardiography of Olympic Athletes

Relationship between QRS‐duration (heart score) and racing performance in trotters

“…Further, horses with high heart scores (ie,> 120 milliseconds (msecs)) tended to race more successfully than horses with lower heart scores. A similar relationship has been demonstrated in human athletes (Steel, Stewart and Toyne 1970).…”

“…Care was taken to ensure that the horse was relaxed and stood with an even distribution of weight support upon all 4 limbs, the left forefoot being placed slightly in front of the right foot. The importance of the posture for QRS form and T wave direction has been previously reported (Holmes and Alps 1967;Steel and Stewart 1974). Silver-plated electrodes were applied just distal to the elbow and stiffle joints by means of rubber straps and the 3 standard limb leads plus the 3 augmented voltage (AV) leads were recorded.…”

“…Heart scores were "measured" by the method described by Steel and Stewart (1974). A calibrated magnifying lens was used to measure the QRS duration in the standard limb leads and heart score was derived as the arithmetic mean of these 3 readings.…”

Effects of endurance training on standard and signal-averaged electrocardiograms of sled dogs

“…7,11,12,14,15,[22][23][24] Although there is a clear dependence of QRS duration on age and body weight in mammals, 25 it is believed that QRS duration in mature animals is not altered by endurance training. 4,26 On the basis of our results from cross-sectional studies in sled dogs 7 and gray wolves, 9 we hypothesized that a longitudinal study would confirm that QRS duration increases with endurance training. Accordingly, our major hypothesis was that endurance training increases QRS duration in sled dogs.…”

“…E ndurance training induces major cardiovascular adaptations that are manifest as auscultable cardiac murmurs, bradyarrhythmias, an increased Rwave amplitude in selected electrocardiographic leads, increases in QRS duration and QT interval, and echocardiographic evidence of cardiac chamber enlargement. [1][2][3][4][5][6] These changes are believed to reflect functional and morphologic adaptations of an athlete's heart in response to sustained endurance exercise rather than evidence of cardiovascular disease. 3 Of interest is whether measurement of these functional and morphologic changes provides a useful method for predicting performance in endurance activities.…”