ABC | Volume 115, Nº1, July 2020

Original Article Vargas & Rigatto Parents’ BP and young men autonomic impairment Arq Bras Cardiol. 2020; 115(1):52-58 with an increase in maximal oxygen uptake (VO 2max ), 10 i.e., there is a relationship between the parasympathetic modulation and the functional capacity of the cardiovascular system. There is also a consensus that there is a strong relationship between VO 2max and arterial endothelial function (EF), since they are dependent variables. 11 However, data from our laboratory have shown, in a normotensive group of young soccer players, that a difference of 10 mmHg in mean BP is enough to change the autonomic balance, without changing VO 2max and EF. 12 Although it is not possible to conclude whether BP or autonomic balance is the cause or the consequence, this result indicates that the alteration in autonomic balance probably precedes the VO 2max or EF changes. Thus, our study was designed to compare the autonomic modulation, the EF, and the VO 2max of young athletes grouped according to the parents’ BP history. The objective was to access the influence of the genetic background in those parameters, and whether normotensive athletes would present differences in the cardiovascular system control that could compromise their performance. Additionally, our intention is also to drive attention for the importance of preventing cardiovascular diseases and finding out which system is the first to be compromised in normotensive subjects with a family history of hypertension. Methods The Ethics Committee of the Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) approved the study (CEP/UFCSPA protocol number 562.572). The sample size was calculated with a confidence level of 95%, applying a tolerated measurement error estimated at 5% over the mean of variable standard deviation of normal RR intervals (SDNN) of anterior study. 11 Thus, in order to conduct this research project, a minimum number of 39 participants was required. Predicting losses and dropouts around 20% of the sample number, 46 individuals were invited to participate. Forty-six young male soccer players (18±2 years of age) were submitted to: anthropometric and BP measurements, autonomic nervous system and EF evaluation, and exercise tests. All players had at least two years of previous soccer- specific training and lived in the club accommodations to avoid significant differences in lifestyle. Moreover, all meals were provided assuring similar diet and nutrients intake. Before data collection, the athletes were fully informed about the tests to be performed and provided a written informed consent to participate. The data was collected during the soccer preseason, when the athletes were training, but not participating in any competitions. All evaluations were made on Tuesdays, before training, respecting the athletes’ rest breaks. The athletes trained on Sundays, rested on Mondays, and returned to training on Tuesdays. To avoid any tendency in data interpretation, all data collection were performed before the subjects were allocated in the groups. The athletes were instructed to attend the Laboratory of Physiotherapy/UFCSPA, at 7 a.m., fasting. The BP and HR were measured, followed by an evaluation of EF in the brachial artery. To avoid an excess of measurements in a single day, the anthropometric data (height, weight, age, body fat percentage, and time of training) and VO 2max were collected one week later. The athletes were grouped according to their family history of hypertension: 1- normotensive father and mother (FM-N), with 14 athletes; 2- only father was hypertensive (F-H), with 11 athletes; 3- only mother was hypertensive (M-H), with 10 athletes; and 4- father and mother were hypertensive (FM-H), with 11 athletes. Following the guidelines for this assessment, 13 the BP of the athletes was measured, as well as their parents’. The hypertensive status of the athletes’ parents was previously defined by a physician (53.3% of those individuals were taking anti-hypertensive drugs and 3.3%were not treating their state). Individuals who showed changes in BP values were advised to seek medical attention. Blood pressure measurement An auscultatory method was used. The athletes were kept in a quiet environment for at least five minutes before BP measurements, seated with their feet on the floor, right arm supported at heart level and BP cuff covering at least 80% of the upper arm. To confirm the data, the BP measurement was repeated at least twice at 2-minute interval. When a difference of more than 6 mmHg was detected in two successive measurements, the measurements were repeated until the difference was less than 4 mmHg. For each athlete, an average of two measurements was used to obtain the SBP. 13 Heart rate variability A Polar model RS800CX heart-rate monitor (Polar Electro Öy, Kempele, Finland) was used to collect heart rate (HR) data at a sampling frequency of 1000Hz. For the evaluation of HRV, the athletes were instructed to lie quietly on a stretcher in the supine position. After 10 minutes, still in the supine position, the HR signal was recorded for 10 minutes followed by additional 10 minutes with the athlete standing in front of the stretcher. 13 The signal was automatically stored as an RR interval and analyzed with Kubios HRV software version 2.0 (University of Kuopio, Kuopio, Finland). A 1,000-Hz sampling rate was chosen to provide a temporal resolution of 1 ms for each RR interval, a standard deviation of normal RR intervals (SDNN, ms), the square root of the mean squared differences among consecutive RR intervals (RMSSD, ms), the number of interval differences of successive NN intervals greater than 50 ms (NN50, ms), and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50; ms) 8 . An autoregressive method was used to determine HRV, based on the spectral power integrated in two frequency bands: (i) a high-frequency (HF) band from 0.15 to 0.4 Hz; and (ii) a low-frequency (LF) band from 0.03 to 0.15 Hz. The results were expressed in absolute values (HFa and LFa, ms 2 ) and their respective percentages (HFnu and LFnu, %). The LF/HF ratio (ms 2 ) was calculated according to the LFa and HFa. 8 This methodology had been previously reproduced in the soccer players. 11 Endothelial Function Assessment EF was assessed noninvasively by means of a brachial artery ultrasound probe (GE Medical Systems, Vivid I Ultrasound, Israel) and Doppler ultrasonography, using an instrument 53