Efeito do German Volume Training (GVT) nas variáveis autonômicas em diferentes fases do ciclo menstrual em mulheres jovens

Abstract

Introduction: The menstrual cycle (MC) is a physiological change that occurs in fertile women, being characterized by the follicular and luteal phases. Thus, is necessary to establish the relationship between the hormonal fluctuations of the MC and the influence of the GVT method on the parameters of heart rate variability (HRV) and on the training volume of women in each phase of the menstrual cycle. Therefore, it is important to identify whether any phase of the menstrual cycle is more appropriate to perform more intense and higher volume training and its impact on autonomic variables. And, also, if there is an adequate time for recovery after performing the GVT in the different phases of the cycle. Objective: To evaluate the effect of German Volume Training (GVT) on heart rate variability at different stages of the menstrual cycle in young women. Material and Methods: The study included 9 women (21 to 31 years old), physically active for at least one year, who trained strength at least three times a week. To start the protocol, the participants attended the laboratory fasting (at least 8 hours). Then, they were at rest in the supine position for 10 minutes, after which the heart rate variability at rest was measured for 5 minutes. Then, blood was collected to analyze the blood concentration of the hormones Estrogen and Progesterone. At the end of the blood collection, a standardized meal was offered. The GVT protocol started after 1 hour of meal ingestion. Initially, a warm-up of a series of 10 repetitions was performed, with 50% of the load obtained in the 1 RM test. After a two-minute interval, the first series of the protocol was performed (80% of 1 RM). Participants were instructed to perform 10 sets until concentric failure, with a 1-minute interval between each set on the 45° leg press machine. At the end of each series, the Subjective Perception of Effort (PSE - OMINI) scale was used. The HRV collection was in the pre-exercise moments, immediately after, 24 and 48 hours, the collection time was 5 minutes. Results: The concentration of the hormone progesterone was significantly higher (p = 0.0001) in the luteal phase when compared to the follicular phase. There was no significant difference for estrogen concentration. The load in the 1RM test was statistically higher (p = 0.0065) in the luteal phase (174.67 ± 53.89 kg) compared to the follicular phase (167.67 ± 48.74 kg). In HRV, two-way ANOVA revealed that there is no effect of the interaction between time and menstrual cycle phases in the time domain (HR, SDNN, RMSSD, PNN50). There was also no statistical difference between the phases, however, there is an effect of time. There was a significant difference in relation to the pre, and, 24 and 48h in relation to the post. No significant difference was shown at 24 and 48 h in relation to pre-time. Furthermore, in the frequency domain (LF, HF, LF:HF) there is no effect of the interaction between time and menstrual cycle phases. There was also no statistical difference between the phases and the effect of time. Conclusion: The German Volume Training training method was able to significantly alter the sympathovagal balance soon after its execution. However, the same did not occur for moments 24 and 48 hours later. The total training volume did not differ in the phases of the menstrual cycle.