From the Guidelines
A heart rate of 46 beats per minute (bpm) is considered normal in an athlete. According to the international recommendations for electrocardiographic interpretation in athletes 1, heart rates ≥ 30 beats/min are considered normal in highly trained athletes. This is because athletic training increases the heart's efficiency, allowing it to pump more blood with each contraction, resulting in a slower heart rate. The study published in the Journal of the American College of Cardiology in 2017 1 supports this, stating that sinus bradycardia, defined as a heart rate of ≤ 30 beats/min, is a normal finding in athletes. Another study published in the same journal in 2017 1 also notes that a resting heart rate ≤ 30 beats/min or a PR interval ≥ 400 ms may be normal in a well-trained athlete, but should prompt further evaluation for cardiac conduction disease. However, a heart rate of 46 bpm is well above this threshold, and in the absence of symptoms, is considered a normal adaptation to regular exercise.
Some key points to consider include:
- Athletes, especially those engaged in endurance sports, often develop bradycardia as a beneficial adaptation to regular training 1
- Resting heart rates between 40-60 bpm are common in well-trained athletes, with some elite endurance athletes having rates as low as 30-40 bpm
- If an athlete experiences symptoms like dizziness, fatigue, or fainting with a heart rate of 46 bpm, medical evaluation would be recommended to rule out conditions like heart block or other cardiac issues that might require treatment 1
- The heart's efficiency increases with athletic training, allowing it to pump more blood with each contraction, resulting in a slower heart rate 1
From the Research
Heart Rate in Athletes
- A heart rate of 46 beats per minute (bpm) can be considered normal in an athlete, as sinus bradyarrhythmias are common and even expected in athletes 2.
- Athlete's heart syndrome (AHS) is characterized by increased left ventricle dimensions, thickness, and mass, and can lead to sinus bradycardia, which is a common conduction abnormality in athletes 3.
- Resting heart rate variability (HRV) is a potentially useful marker to consider for monitoring training status in athletes, and can be used to distinguish normal physiological adaptations from potentially concerning conditions 4, 5, 6.
Factors Affecting Heart Rate
- Exercise intensity, duration, modality, and overall training load can affect resting heart rate variability in athletes 6.
- Lifestyle factors, such as sleep and nutrition, can also impact heart rate variability in athletes 6.
- Sex and age differences can also influence heart rate variability, with endurance athletes typically demonstrating better cardiac autonomic function than non-athletes 5, 6.
Monitoring Heart Rate
- Heart rate variability analysis can be used to monitor training status and identify maladaptive states such as overtraining in athletes 6.
- Monitoring tools, such as ECG recordings, can be used to assess heart rate variability in athletes 4, 5, 6.
- The importance of stationarity of data, body position, timing and duration of the recording window, and average heart rate should be considered when analyzing heart rate variability in athletes 6.