Differences in Nervous Autonomic Control in Response to a Single Session of Exercise in Bodybuilders Using Anabolic Androgenic Steroids

Abstract

Considering the role of autonomic nerve activity in blood pressure control, this study aimed to investigate the cardiac autonomic nerve responses after an aerobic exercise session in Anabolic Androgenic Steroids (AAS) users. Twenty men (AAS, n = 9; control group, n = 11) performed an aerobic exercise session (60 min, 70 to 80% of HR_max). Heart rate variability (HRV) was assessed before and during a 60-min post-exercise recovery period. RMSSD (root mean square successive difference of the RR intervals) and the LF/HF ratio (low frequency/high frequency spectra) were also evaluated. The Student's t-test for independent samples was used to compare differences between initial group characteristics. Repeated measures ANOVA was used to compare pre- and post-exercise HRV recovery (p < 0.05). AAS had a lower SDNN (standard deviation of the intervals) (40.8 ± 16.8 vs. 71.6 ± 24.7 ms; p = 0.04, d = 1.4) and a higher LF/HF (3.4 ± 2.1 vs. 1.8 ± 0.9%; p = 0.03, d = 0.9) before exercise. AAS and controls had similar RMSSD (14.0 ± 15.8 vs. 18.9 ± 12.1 ms; p = 0.20) and a LF/HF (2.8 ± 1.6 vs. 2.4 ± 1.2 ms; p = 0.41) immediately post-exercise. The between-groups comparison revealed a higher HF/LF at 30 min (4.3 ± 1.4 vs. 2.5 ± 1.3%; p = 0.008, d = 1.3) and 60 min (5.0 ± 2.2 vs. 2.3 ± 0.8%; p = 0.001, d = 1.6) for the AAS group in the recovery time. This study demonstrated impaired parasympathetic activity at rest and immediately after the exercise session as an adverse effect of AAS usage, but similar behavior regarding the restoration of sympathetic activity.

Keywords: anabolic agents; autonomic nervous system; heart rate variability; physical exercise.

Figure 1

Schematic view of the exercise and evaluation protocol. HR, heart rate; HRV, heart rate variability.

Figure 2

Heart rate (panel A), heart rate variability in time (RMSSD, panel B), Standard Deviation of the intervals (SDNN, panel C) and frequency (LF/HF, panel D) domains at pre-, post- and during 60-min of recovery after the aerobic exercise session. AAS, anabolic androgenic steroids users; RMSSD, square root of the mean squared differences of successive RR intervals; LF/HF, low-frequency/high-frequency ratio (sympathovagal balance). Data are presented as mean ± standard deviation of the means; * Significant difference Control (n=11) vs. AAS (n=9); # significant intragroup differences at rest; p < 0.05.