PHYSICAL TRAINING IN ATHLETES: ANALYSIS OF CARDIAC AUTONOMIC MODULATION

ABSTRACT Introduction Cardiac autonomic modulation (CAM) is a result of the balance between the sympathetic and parasympathetic systems. This interaction results in heart rate variation (HRV), analyzed by specific electrocardiographic parameters. These parameters are modified by the practice of physical activity, indicating better cardiac conditioning. Objectives To evaluate the cardiac autonomic modulation of athletes of the XXVIII Ecological Walk at two separate times during their period of physical training. Also, to link the practice of physical activity with stress reduction in these individuals. Methods 24-hour Holter exams were performed at two times (before and after a 2-month period of non-standard physical training), and the results were analyzed using the software programs Epi-Info 7 and BioEstat 5.0. Inferential analysis was performed by the nonparametric Shapiro-Wilk test. Statistical significance was assigned to p values less than 0.05, with 95% confidence interval (95% CI). Results The sample was mostly male (n = 14; 77.78%), with a mean age of 49.55 years. No individual trained for less than 60 days; most (47.06%) trained for 151-200 days, with walking being the predominant modality (64.71%). No statistically significant difference was found in the parameters HRV pNN50 (p = 0.18), rMSSD (p = 0.14) or HF (p = 0.117) after the evaluated training period. Conclusions Participants who are longtime sportsmen and physically active showed parasympathetic saturation, therefore, they did not show significant changes in HRV. Also, low levels of stress were observed in those who practiced physical activity. Level of evidence II; Prognosis Study.摘要 引言 心脏自主神经调节（Cardiac autonomic modulation, CAM）是交感神经系统与副交感神经系统相互平衡的产物。二者的相互作用会产生心率变异性（Heart rate variation, HRV），可通过特定心电图参数进行分析。体育锻炼可改变此类参数，提示心脏适应能力的提升。 研究目的 评估第28届生态徒步活动参与者在其体育训练周期内两个不同时间点的心脏自主神经调节情况，并探讨体育锻炼与该类个体应激水平降低之间的关联。 研究方法 分别在为期2个月的非常规体育训练前后两个时间点，为受试者开展24小时动态心电图（Holter）检查，采用Epi-Info 7与BioEstat 5.0软件对检测结果进行分析。采用非参数Shapiro-Wilk检验开展推断性统计分析，以p值小于0.05作为统计学显著性判定标准，置信区间设置为95%（95% CI）。 研究结果 研究样本以男性为主（n=14，占比77.78%），平均年龄为49.55岁。所有受试者的训练时长均不少于60天，其中47.06%的受试者训练时长为151~200天，步行为最主要的运动形式（占比64.71%）。经评估的训练周期结束后，心率变异性相关参数pNN50（p=0.18）、rMSSD（p=0.14）及HF（p=0.117）均未出现统计学显著差异。 研究结论 长期从事运动且规律锻炼的受试者出现了副交感神经饱和现象，因此其心率变异性未出现显著变化。此外，参与体育锻炼的受试者应激水平普遍较低。 证据等级：Ⅱ级；研究类型：预后研究。