Objective Identify key determinants of heart rate variability (HRV) in male athletes aged 14–21 years participating in competitive contact sports and integrate these determinants to define normative short-term HRV values.

Design Transverse.

Setting Secondary care.

Participants 369 male contact sports athletes aged 14 to 21.

Interventions (or Assessment of Risk Factors) HRV was measured for 5 minutes at rest.

Outcome Measures Standard HRV parameters in the time and frequency domains were calculated. Normative limits for the corrected HRV parameters were established.

Main Results Heart rate (HR), age, body mass index, number of sports weekly practices, and concussion history were considered potential determinants that could influence HRV. Multiple regression analysis revealed that HR was the primary determinant of standard HRV parameters. The models accounted for 13–55% of the total variance in HRV. The contribution of HR to this model was significant (β ranged from -0.34 to -0.75). Therefore, the HRV parameters were normalized and their normative limits were developed relative to the mean heart rate. After corrections, these parameters were no longer dependent on any potential determinant, and normal value ranges were calculated for the HRV time- and frequency-domain indices.

Conclusions In this study, corrected normative values of short-term and resting state HRV parameters are provided. These values were developed independently of the major determinants of HRV. The baseline values for HRV parameters provided by the present study could be used in clinical practice during the assessment and follow-up of concussions and may assist in decision-making for a safe return to play.