Exercise Training Improves Heart Rate Variability after Methamphetamine Dependency

DOLEZAL, BRETT ANDREW1; CHUDZYNSKI, JOY2; DICKERSON, DANIEL2; MOONEY, LARISSA2; RAWSON, RICHARD A.2; GARFINKEL, ALAN3; COOPER, CHRISTOPHER B.1

Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0000000000000201
Clinical Sciences
Abstract

Purpose: Heart rate variability (HRV) reflects a healthy autonomic nervous system and is increased with physical training. Methamphetamine dependence (MD) causes autonomic dysfunction and diminished HRV. We compared recently abstinent methamphetamine-dependent participants with age-matched, drug-free controls (DF) and also investigated whether HRV can be improved with exercise training in the methamphetamine-dependent participants.

Methods: In 50 participants (MD = 28; DF = 22), resting heart rate (HR; R-R intervals) was recorded over 5 min while seated using a monitor affixed to a chest strap. Previously reported time domain (SDNN, RMSSD, pNN50) and frequency domain (LFnu, HFnu, LF/HF) parameters of HRV were calculated with customized software. MD were randomized to thrice-weekly exercise training (ME = 14) or equal attention without training (MC = 14) over 8 wk. Groups were compared using paired and unpaired t-tests. Statistical significance was set at P ≤ 0.05.

Results: Participant characteristics were matched between groups (mean ± SD): age = 33 ± 6 yr; body mass = 82.7 ± 12 kg, body mass index = 26.8 ± 4.1 kg·min−2. Compared with DF, the MD group had significantly higher resting HR (P < 0.05), LFnu, and LF/HF (P < 0.001) as well as lower SDNN, RMSSD, pNN50, and HFnu (all P < 0.001). At randomization, HRV indices were similar between ME and MC groups. However, after training, the ME group significantly (all P < 0.001) increased SDNN (+14.7 ± 2.0 ms, +34%), RMSSD (+19.6 ± 4.2 ms, +63%), pNN50 (+22.6% ± 2.7%, +173%), HFnu (+14.2 ± 1.9, +60%), and decreased HR (−5.2 ± 1.1 bpm, −7%), LFnu (−9.6 ± 1.5, −16%), and LF/HF (−0.7 ± 0.3, −19%). These measures did not change from baseline in the MC group.

Conclusions: HRV, based on several conventional indices, was diminished in recently abstinent, methamphetamine-dependent individuals. Moreover, physical training yielded a marked increase in HRV, representing increased vagal modulation or improved autonomic balance.

Author Information

1Exercise Physiology Research Laboratory, Departments of Medicine and Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA; 2Integrated Substance Abuse Programs, Semel Institute, David Geffen School of Medicine, UCLA, Los Angeles, CA; and 3Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA

Address for correspondence: Brett Andrew Dolezal, Ph.D., Exercise Physiology Research Laboratory, Department of Medicine, David Geffen School of Medicine, 10833 Le Conte Ave, 37-131 CHS, University of California, Los Angeles, Los Angeles, CA 90095; E-mail: bdolezal@mednet.ucla.edu.

Submitted for publication May 2013.

Accepted for publication October 2013.

© 2014 American College of Sports Medicine