Electrocardiographic Findings of Heart Rate and Conduction Times in Athletic Students and Sedentary Control Subjects

Bjørnstad, Hans; Storstein, Liv; Meen, Helge Dyre; Hals, Ottar

doi:10.1159/000175979

Cited by 10 publications

(6 citation statements)

References 18 publications

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“…These results are in agreement with previous reports that have shown a depression on A-V conduction in athletes that evidenced first degree and, to a lesser extent, second degree of A-V block (20,25,26). The depressing effects of physical training on A-V nodal conduction have been attributed to an increased vagal tone (2,12). Our results indicate the intervention of an intrinsic component in the alteration of A-V conduction.…”

Section: Discussionsupporting

confidence: 93%

“…Some authors support the fact that the reduction in heart rate (HR) at rest as a consequence of endurance training is the result of an increased vagal tone (18,19) and not because of a reduction in the intrinsic HR (17). The concept of an increase in the parasympathetic activity by training is supported by the observations of increased acetylcholine levels in the myocardium of trained animals (2), as well as a greater gain of baroreceptive mechanisms in trained animals (1). Conversely, several reports support the fact that electrophysiological training-induced modifications are the result of intrinsic mechanisms.…”

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confidence: 99%

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Intrinsic changes on automatism, conduction, and refractoriness by exercise in isolated rabbit heart

Such

Rodriguez

Alberola

et al. 2002

Journal of Applied Physiology

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We have studied the intrinsic modifications on myocardial automatism, conduction, and refractoriness produced by chronic exercise. Experiments were performed on isolated rabbit hearts. Trained animals were submitted to exercise on a treadmill. The parameters investigated were 1) R-R interval, noncorrected and corrected sinus node recovery time (SNRT) as automatism index; 2) sinoatrial conduction time; 3) Wenckebach cycle length (WCL) and retrograde WCL, as atrioventricular (A-V) and ventriculoatrial conduction index; and 4) effective and functional refractory periods of left ventricle, A-V node, and ventriculoatrial retrograde conduction system. Measurements were also performed on coronary flow, weight of the hearts, and thiobarbituric acid reagent substances and glutathione in myocardium, quadriceps femoris muscle, liver, and kidney, to analyze whether these substances related to oxidative stress were modified by training. The following parameters were larger (P < 0.05) in trained vs. untrained animals: R-R interval (365 +/- 49 vs. 286 +/- 60 ms), WCL (177 +/- 20 vs. 146 +/- 32 ms), and functional refractory period of the left ventricle (172 +/- 27 vs. 141 +/- 5 ms). Corrected SNRT was not different between groups despite the larger noncorrected SNRT obtained in trained animals. Thus training depresses sinus chronotropism, A-V nodal conduction, and increases ventricular refractoriness by intrinsic mechanisms, which do not involve changes in myocardial mass and/or coronary flow.

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Section: Discussionsupporting

confidence: 93%

mentioning

confidence: 99%

Intrinsic changes on automatism, conduction, and refractoriness by exercise in isolated rabbit heart

Such

Rodriguez

Alberola

et al. 2002

Journal of Applied Physiology

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“…We have furthermore found a negative corre lation between indices of left ventricular hy pertrophy (Sokolow-Lyon and Grant) and heart rate [15]. The mechanisms underlying the bradycardia of training have been dis cussed in a separate paper [17], Diurnal varia tions in heart rate were marked (table 2) and the difference between the highest and lowest mean heart rate was 22.5 beats/min in ath letes, 23.9 beats/min in students and 29.3 beats/min in control subjects ( fig. 1).…”

Section: Heart Ratementioning

confidence: 58%

Ambulatory Electrocardiographic Findings in Top Athletes, Athletic Students and Control Subjects

et al. 1994

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Aim of the present study was to evaluate 24 h electrocardiographic recording in 30 top athletes, 30 athletic students and 30 sedentary control subjects. Each group consisted of 15 males and 15 females and were matched for age (about 24 years). Training was not allowed during the recording. Top athletes had the lowest diurnal and nocturnal heart rate, but the difference between top athletes and athletic students was far less pronounced than between athletic students and controls. This may indicate that bradycardia reaches a lower limit with moderate degrees of training. Atrioventricular (AV) block II was found in 3 top athletes and 4 athletic students and in none of the subjects, the longest pause being 2.4 s in both athletic groups. Most episodes occurred during night and nearly all were Mobitz type I. In all cases of AV block II the QRS complexes were narrow and AV block III did not occur. SA block was found in 3 top athletes, 1 athletic student and 1 control subject, the longest pause being 3.1, 2.9 and 1.9 s, respectively. Ventricular premature beats were rare in all groups and complex ventricular arrhythmias were not found. Half of the subjects were in Lown class 0, the other half in Lown class 1. Supraventricular premature beats were also scarce and most frequent in top athletes, followed by athletic students and sedentary controls (2.0, 1.0, 0.7 beats/h, respectively).

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“…Normal sinus rhythm [39] was more com mon in women while sinus bradycardia was more frequent and sinus tachycardia less fre quent in males. AV block I was three times as frequent in males, notching of R/S in V |-V 2 almost twice as frequent and incom plete right bundle branch block seven times more frequent in males.…”

Section: Sex Differences In Heart Size and Body Buildmentioning

confidence: 91%

Electrocardiographic Findings according to Sex in Athletes and Controls

Storstein

Bjørnstad²,

Hals

et al. 1991

Cardiology

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We have previously compared the electrocardiogram of 1,299 male and female students of physical education and sports with 151 age- and sex-matched sedentary controls and found that the former had lower heart rate, longer conduction times and increased voltages. The same material of 1,450 young adult subjects was split according to sex into 617 females and 833 males in order to analyze the influence of gender on the resting 12-lead electrocardiogram. We found that females had a significant higher heart rate, shortened conduction times (PQ, Q, ventricular activation time and QRS) and a prolonged repolarization time (QT_C), decreased P, Q and T amplitudes as well as indices of right, septal and left hypertrophy, and ST elevation in precordial leads were lower in females than in males. These differences were highly significant with p values < 0.0001 for almost all parameters. Sinus bradycardia was more common in men and sinus tachycardia in women. The prevalence of other rhythms and supraventricular and ventricular premature beats was low in both sexes. AV block grade I was found in 1 % of females and 3% of males (p < 0.02). Notching of R/S in V₁ – V₂ and incomplete right bundle branch block were less common in females (p < 0.0001). The differences in ECG parameters between the two sexes in the total material persisted also when the athletic and control groups were investigated separately. Gender seems to be highly important for most ECG parameters in the resting ECG. This points to the necessity of discussing different upper normal limits for ECG parameters according to gender.

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Electrocardiographic Findings of Heart Rate and Conduction Times in Athletic Students and Sedentary Control Subjects

Cited by 10 publications

References 18 publications

Intrinsic changes on automatism, conduction, and refractoriness by exercise in isolated rabbit heart

Intrinsic changes on automatism, conduction, and refractoriness by exercise in isolated rabbit heart

Ambulatory Electrocardiographic Findings in Top Athletes, Athletic Students and Control Subjects

Electrocardiographic Findings according to Sex in Athletes and Controls

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