Introduction and Purpose:
Rigorous training of elite athletes can lead to nonfunctional overreaching (NFOR) and overtraining (OT), both of which decrease performance and increase the risk of injury. Heart rate variability (HRV) is a measure of autonomic nervous system balance. Reductions in HRV are associated with NFOR and OT. Breath-based biofeedback increases HRV through activation of the baroreceptor reflex.
This case study explored the impact of breath-based HRV biofeedback (HRV-BF) training on daily resting HRV values of a female triathlete and the association between daily HRV with subjective performance indicators of workout quality and amount of postworkout energy.
A 24-year-old female triathlete completed an 8-week A-B repeated-measures study—A: baseline; 4 weeks and B: intervention HRV-BF training; 4 weeks. The subject recorded daily resting HRV for 120 seconds, completed regular daily training, and measured workout performance and postworkout energy levels on a 0 to 10 scale. During B, the subject added 15 minutes of HRV-BF 5 times per week.
With HRV-BF, median HRV level increased (A: 137; B: 191) and the interquartile band narrowed (A: 83–184; B: 142–201), suggesting higher HRV with less variability. The subject had more days at highest readiness (A: 35%; B: 62%). Median values for reports of workout performance and postworkout energy increased.
This study found that, for this subject, 15 minutes of HRV-BF, 5 times per week, was associated with increased HRV and improved subjective workout performance. Further research exploring HRV measures and biofeedback to inform athletic performance is warranted.