Improving physical fitness requires putting stress on your system during vigorous workouts. But the quest for peak performance often backfires—the psychophysiological distress caused by excessive exercise isn’t good for you. Finding a “Goldilocks zone” where your daily workouts put enough stress on your body to improve fitness without overdoing it can be tricky.
Chris Bergland finishing a Triple Ironman in the early 2000s.
Source: Chris Bergland
For example, when I was trying to get in shape for extreme events like the Triple Ironman (7.2-mile swim, 336-mile bike, 78.6-mile run), the risk of injury and burnout was extremely high. Monitoring fluctuations in my heart rate variability (HRV) was a way to make sure I wasn’t overtraining.
In addition to keeping tabs on how my nervous system responded to the previous day’s