Unclear outcomes of heart rate variability following a concussion: a systematic review

ABSTRACT

Purpose

: To systematically regroup articles that were published since the latest systematic search, but with specific inclusion criteria to help comparison that will offer a focused presentation of methods and results. This will offer a full overview of HRV’s behavior at rest and during exercise in adults post-concussion.

Methods

: The systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. A computer-based systematic search was conducted in December 2019 through the Pubmed, Scopus and SPORTDiscus databases. A manual search was performed through the reference list of all articles retained. The reliability of the systematic search was assured by having the article selection process entirely repeated by a second author.

Results

: The systematic search yielded a total of 15 articles to be further analyzed. Results show impairment of HRV during exercise for individuals with concussion, heterogenous studies with lack of control over confounding factors and only less than half of the results showing a significant difference between individuals with concussion and controls.

Conclusion

: Further research should try standardizing HRV measurement protocols that control confounding factors to allow easier comparison between studies and allows the possibility for an eventual meta-analysis.

KEYWORDS:

• Heart rate variability
• concussion
• mTBI
• cardiac autonomic function
• ANS

List of abbreviations

MTBI: Mild Traumatic Brain Injury

HRV: Heart Rate Variability

LF: Low Frequency Power

HF: High Frequency Power

RMSSD: Root Mean Square of Successive Differences

CVRR: Coefficient of Variation of the RR Intervals

SDRR: Standard Deviation of the RR Intervals

SampEn: Sample Entropy

IHGT: Isometric Hand Grip Test

Aknowledgement

Authors would like to thank all researchers referenced in this study, as well as all scientific investigations that were read, but unfortunately not included.

Declaration of interest

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.