The importance of heart rate monitors in controlling intensity during training and competition in junior biathlon athletes

Purpose: This study examines whether junior athletes successfully regulate training intensity using subjective feeling, or whether heart rate monitor is necessary to regulate intensity. Methods: Nine active junior biathlon athletes, men (n = 6) and women (n = 3) between 16 and 19 years old participated in the study. All participants completed two training sessions at lactate threshold, one session regulated by subjective feeling, blinded for heart rate and one session regulated by heart rate. Results: The participants start the first ten minutes of the training session at lower intensity when blinded, compared to using HR monitors (ES, 0.98; P = 0.05). Registrations at 20 and 30 minutes shows that participants in the non-blinded session gradually tune in to the right intensity, and the differences get smaller and non-significant. Mean speed (ES, 0.61; P = 0.04) and distance covered (ES, 0.63; P = 0.04) during the training session is larger in the heart rate controlled session compared to subjective feeling. Conclusions: Using heart rate monitors provide better control of exercise intensity in young biathletes than subjective feeling. Using subjective feeling underestimate intensity at lactate threshold, and results in significantly, lower distance covered.