Heart rate, electrocardiographic parameters and arrhythmias during agility exercises in trained dogs.

摘要

This study aims were to analyze heart rate (HR) response to exercise, to determine the electrocardiographic characteristics and the incidence of arrhythmias during exercise and recuperation in agility-trained dogs. Fifteen trained dogs performed an agility competition (AC) over a distance of 360-400 m with 40 obstacles. HR was monitored throughout the AC and for the first 30 min of recovery. Electrocardiograms were recorded at rest, immediately after AC and at 5, 15 and 30 min of recuperation in leads I, II, III, aVR, aVF and aVL. Morphology, duration and voltage of the waves, as well as durations of segments and intervals were measured. AC implied a cardiovascular load of 71.67% of the maximal HR (HRmax), with two main ranges: between 45-50% and 70-75% of HRmax. Agility dogs had lower P and R-wave voltages and shorter QRS and QT durations but higher PQ duration than other canine athletes (sled dogs and Greyhounds). All animals showed vagal-induced arrhythmias before AC, and their incidence decreased during the first 15 min of recovery. None of the dogs developed pathological arrhythmias. It is concluded that AC does not require as much cardiovascular work as short-maximal (racing) or prolonged-submaximal (sled) competitions and the results suggest a lesser degree of training-induced heart hypertrophy than in other canine athletes. This kind of exercises would be proposed in training programs to improve cardiovascular fitness.