ALTERACIÓN DE LA FRECUENCIA CARDÍACA DE JUGADORES DE BÁSQUET EN ENTRENAMIENTO DE RESISTENCIA

rbme Revista Brasileira de Medicina do Esporte Rev Bras Med Esporte 1517-8692 1806-9940 Sociedade Brasileira de Medicina do Exercício e do Esporte RESUMEN Introducción: Muchos jugadores tienen un alto nivel de entrenamiento en el actual equipo chino de baloncesto. Sin embargo, los atletas tienden a tener problemas relacionados a la frecuencia cardiaca en competiciones oficiales. Por lo tanto, es importante monitorear y controlar la frecuencia cardíaca con el fin de obtener mejoría de desempeño en los jugadores. Objetivo: Investigar la frecuencia cardíaca en los jugadores de baloncesto en entrenamientos intermitentes de resistencia. Métodos: Los investigadores seleccionaron 28 jugadores de baloncesto en una universidad como objeto de estudio. Estos atletas realizaron entrenamiento de resistencia intermitente donde fueron medidas, antes y después del entrenamiento, la variabilidad de sus frecuencias cardíacas, los cambios en los indicadores de frecuencia y los cambios en la función cardíaca. Resultados: Después del entrenamiento, la Potencia Total (TP), la Alta Frecuencia (HF), la HFnorm y la Baja Frecuencia (LF) fueron significativamente más altas que las mediciones previas al entrenamiento. El nivel de alteración fue medio para TP (0,7), moderado para HF (0,72), medio para HFnorm (0,59) y moderado para LFnorm (0,57). En el caso de LF/HF y LF, el tamaño de la alteración fue de 0,48, cercana al valor crítico del efecto medio. Conclusiones: El entrenamiento de resistencia intermitente puede mejorar la resistencia del nervio cardiovagal en los jugadores universitarios de baloncesto, aumentar la capacidad cardíaca y mejorar significativamente la función cardíaca.. Nivel de evidencia II; Estudios terapéuticos – investigación de resultados de tratamiento. INTRODUCTION In the current Chinese basketball team, many athletes usually train at a higher level, the technology has been used well, but in the official competition, especially in fierce competitions with considerable strength, the technical level is out of order.1 In the heavy exercise training class, some exercises, on the surface, practice the players to a greater degree, but ignoring the rotation relationship between the players, thus lengthening the interval time, make the whole degree at a lower level.2 Undeniable, exercise intensity is a problem that all coaches attach great importance to in basketball training. In most of the heavy exercise training classes of the survey subjects, have a considerable degree, and the heart rate has reached a high level, however, the heart rate below 20 times/10” in the heavy exercise training class accounts for 86-14.3% of the class time.3 Long pauses and multiple pauses, decrease the heart rate and increase the fluctuation of the heart rate interval, its balanced heart rate is affected by the low heart rate during long intermittent periods, which is the root cause of the lower level. Therefore, the length of the interval not only affects the maintenance of the heart rate level, it is also meaningful to the formation of the heart-ze curve trend.4 In a training class with a certain level, short intervals and multiple intervals will inevitably make the heart-timing curve unrecovered, the formation of the combination of long and short intervals will inevitably bring the heart rate curve to a preliminary recovery state, based on the above situation, there are reasons to believe that, long intervals during high-volume training are the prominent cause of the drop in heart rate.5 METHOD Research objects The subjects were 28 male basketball players from a certain university. The basic information is shown in Table 1. Table 1 Basic information of subjects. Sample size Age Weight Height 28 20-22 84.61-98.12 188.93-193.65 Experimental method Carry out 8 weeks of intermittent endurance training, monitor the athlete's training load and interval time, strictly control the intermittent heart rate.6 Before and after training, use safe and effective, and the experimental equipment that does not have any damage to the athletes can detect the relevant indicators of the athletes’ physiological functions, a comparative analysis of various indicators before and after training.7 Interval endurance training content (1) Training method Using the intermittent running training method, during training, strictly control the heart rate during the interval, ensure that the interval between each time can restore the athlete's heart rate to 120-130 beats/min, do the next set of training, use positive recovery methods during intermittent periods. The training content is divided into two parts, the first part is basic training and resistance training, The second part is physical fitness and technical and tactical coordination. According to the heart rate value displayed by the polar meter during training, monitor the athlete's heart rate. Basic training and technical and tactical training will take a break when the heart rate reaches 160-170 beats/min, resist resistance training and physical fitness training should rest when the heart rate reaches 180-190 beats/min. (2) Heart rate variability test method The subject is lying flat, perform limb leads. Apply conductive liquid to the conductive clip, then clamp the conductive clip on the left wrist of the subject in the order of yellow, green, red, and black and about 2-3cm above the left ankle, about 2-3cm above the right wrist and right ankle. RESULTS Changes in time domain indicators of heart rate variability As shown in Figure 1, after training, the time domain indicators RMSSD, SDSD, PNN50, and SDNN are all significantly higher than before training, the differences are statistically significant. It shows that basketball players’ vagus nerve regulation ability is enhanced after training. SDNN represents the overall regulation ability of the sympathetic nerve and the vagus nerve; The three indicators of RMSSD, SDSD and PNN50 all reflect the magnitude of vagus nerve tension. The increase in SDNN does not completely represent the enhancement of the athlete's sympathetic nerve regulation ability, therefore, it is necessary to use the frequency domain index for in-depth discussion. And the effect size of RMSSD=0.65, showing a moderate effect; The effect size of SDSD = 0.79, showing a moderate effect; The effect size of PNN50 = 0.80, showing a high effect, it can be considered that the above indicators are greatly affected by the independent variable intermittent endurance training.8 Figure 1 Changes in time-domain indicators of heart rate variability before and after training.. Changes in the frequency domain index of heart rate variability As shown in Table 2, after training, TP, HF, HFnorm, and LF are significantly higher than before training, the differences are statistically significant, there was no significant difference in VLF, LF/HF and LFnorm are significantly lower than before training, the differences are statistically significant. TP showed greater changes after training than before training, the test result is the same as the SDNN in the time domain index. It shows that the autonomic nerve regulation system has improved after training. HF increased significantly, the same as the results of RMSSD, SDSD, and PNN50 in the time domain indicator, shows that the athlete's vagus nerve regulation ability has been improved. The LF/HF index reflects the balance of mutual inhibition of vagus nerve and sympathetic nerve, after training is smaller than before training, at the same time LFnorm. decreases, HFnorm. increases, consistent with the changes in LF/HF, there are significant differences, it shows that basketball players’ sympathetic vagus balance has a vagus trend after training, the control ability of the vagus nervous system is improved. And the effect size of TP = 0.7, showing a medium effect; The effect size of HF=0.72, showing a moderate effect; The effect size of HFnorm=0.59, showing a medium effect; The effect size of LFnorm=0.57, showing a moderate effect; The effect size of LF/HF=0.48, the effect size of LF=0.48, which is close to the critical value of medium effect, it can be considered, the above indicators are greatly affected by the independent variable intermittent endurance training. Table 2 Changes in the frequency domain index of heart rate variability before and after training. Index Before training After training TP 1351.57 ± 903.07 2152.93 ± 1356.81 LF/HF 1.19 ± 1.42 0.69 ± 0.43 HF 667.50 ± 583.74 1131.35 ± 705.10 HFnorm 54.43 ± 17.24 63.39 ± 13.01 LF 500.97 ± 358.48 772.14 ± 707.29 LFnorm 45.57 ± 17.24 36.86 ± 12.77 VLF 183.10 ± 164.90 249.44 ± 157.1 Changes in heart function As shown in Table 3, after training, Avag and SDAW were significantly higher than before training, the differences are statistically significant, Asym. TI is significantly lower than before training, the differences are statistically significant, no significant difference was seen in ApInf. It shows that the central nervous system's regulation of heart activity is reduced after training, the training effect is significantly strengthened, the degree of fatigue is significantly reduced, and there is no significant change in the stress response, the cardiac function reserve increased significantly, the influence factor of the vagus nerve increases, the influence factor of sympathetic nerves is weakened, after training, the athlete's ability to regulate heart function has been significantly improved. Table 3 Changes of cardiac function indexes before and after training. Index influence factor Before training After training Avag 0.27 ± 0.09 0.32 ± 0.09 Asym 36.43 ± 10.12 31.63 ± 7.59 TI 87.30 ± 63.31 58.89 ± 35.73 ApInf 1.70 ± 0.38 1.62 ± 0.27 SDAW 0.026 ± 0.012 0.031 ± 0.008 DISCUSSION The analysis of heart rate variability (HRV) is divided into time domain analysis and frequency domain analysis, frequency domain analysis can make up for the deficiencies of time domain analysis, HRV is further analyzed on the basis of time domain analysis.9 SDNN in the time domain index reflects the overall activity level of sympathetic nerve and vagus nerve, used to evaluate the overall regulation ability of the cardiac autonomic nervous system, RMSSD reflects the level of regulation of the vagus nerve, SDSD reflects the level of vagus nerve regulation ability, PNN50 measures the ability of the vagus nerve to regulate heart rate variability.10 TP in the frequency domain index reflects the overall adjustment ability of the autonomic nervous system, HF reflects the level and change of the vagus nerve, LF mainly reflects the activity level of sympathetic nerves, VLF reflects the function of sympathetic nerve regulation, LF/HF reflects the balance index of sympathetic nerve and vagus nerve, HFnorm and LFnorm. indicate the changes of sympathetic nerve and vagus nerve. Avag reflects the tension of the heart function state, Asym reflects whether the heart function regulation mechanism is mobilized, TI reflects the tension index, ApInf reflects the strength of the stress response, SDAW reflects the level of function reserve. CONCLUSION The intermittent endurance training method can effectively improve the athlete's vagus nerve tension, the increase of the vagus nerve can effectively inhibit the excitability of the heart, reduce the number of heart beats, decrease heart rate. An increase in heart rate can lead to insufficient ventricular filling, this affects the pumping function of the heart, at the same time it will increase the energy consumption of the myocardium, easily cause myocardial fatigue. 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