Heart rate response to effort in athletes with high spinal cord injury
Keywords:
Rugby, Wheelchair, Cardiopulmonary, Heart Rate, Arm Stress TestAbstract
Introduction: Because of descending spinal sympathetic pathways provide tonic control to preganglionic neurons involved in heart rate(HR) control, subjects with spinal cord injuries (SCI) have impaired autonomic cardiac regulation and increased risk of cardiovascular disease. Nevertheless, the literature is very scarce concerning the effects of exercise and training on the autonomic control of subjects with SCI. Objective: In face of this insufficiency of studies on the autonomic control of physically active subjects with SCI, this study aimed at describe the chronotropic response, as well as the heart rate recovery behavior of a sample of elite wheelchair rugby athletes. Methods: This is a cross-sectional study including a convenience sample of 17 elite wheelchair rugby athletes with tetraplegia. The subjects had their anthropometric data measured and underwent a maximal arm ergometry exercise test. A 4-lead electrocardiogram was used to monitor the subjects at rest, throughout exercise and for an 3min period after completion of the test. Heart rate (HR) was computed at five time points: rest (before the test), peak exercise, and 1, 2, and 3 minutes after exercise.Heart rate recovery was computed as absolute and normalized variations.Data distribution was assessed by using the Shapiro–Wilk test and correlations were measured by Pearson's correlation coefficient. Data analysis was performed using SigmaStat 3.5 software (Jandel Scientific, San Raphael, CA, USA). The level of statistical significance was set at P < 0.05.
Results: The subjects presented with HR at rest=69.53±8.3 bpm; HR reserve=66.9±8.3%; Chronotropic Index=47.9±11.8%; HRR at 1’=15.2±7.5 bpm; HRR at 2’=25.2±7.4 bpm; HRR at 3’=37±8.4 bpm. 82.3% of the athletes had HRR at 1’ > 12 bpm, and 64.7% had HRR at 2” above 22 bpm. There were associations between duration of injury and HRR at 1’ (r=-0.5; p=0.0398), peak HR (HRpeak) and total weekly training time (r=-0.591; p=0.0125) and HRpeak and weekly physical training time (r=-0.519; p=0.032). No other correlations were observed. Conclusion: Tetraplegic elite athletes present with reduced chronotropic response. Most of them exhibit a HRR within the values considered normal for the general population.
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