Background: Heart rate coherence (HRC) breathing is a simple paced‑breathing technique intended to support autonomic regulation and recovery. Objective: To evaluate the effects of a four‑week HRC program on (i) heart rate during an ergometer test, (ii) heart rate measured after a standardized 3‑minute recovery period (paced breathing in HRC vs quiet sitting in controls), and (iii) perceived tiredness in amateur female handball players. Methods: Thirty amateur female handball players (22.80 ± 2.75 years) were randomized to an HRC group (n = 15) or a control group (n = 15). Pre‑ and post‑testing included an ergometer test with ECG monitoring and a tiredness rating (Borg scale). Immediately after the test, the HRC group performed 3 minutes of paced breathing (6 breaths/min), whereas the control group sat quietly for the same duration before the post‑recovery heart rate measurement. Results: From pre‑ to post‑test, the HRC group showed substantial reductions in heart rate during the test (161.33 → 136.00 bpm), post‑recovery heart rate (72.93 → 50.73 bpm), and perceived tiredness (4.73 → 2.27). The control group showed minimal changes. ANCOVA indicated significant between‑group effects for all outcomes (p < .005). Conclusion: A four‑week HRC breathing routine added to usual training was associated with lower exercise heart rate, faster post‑exercise cardiac down‑regulation, and reduced perceived fatigue in amateur female handball players.