Training Tuesday: Should You Ignore Heart Rate During Trail Races?

In this episode of Training Tuesday, Bracken Crocker and Kirk DeWint dive into a nuanced debate about heart rate monitoring during trail races, particularly ultras. Bracken argues that heart rate matters significantly less on technical, undulating terrain compared to flat roads, especially in races up to 50 miles. He shares personal data from a 50K where he averaged 170 BPM for over four hours, with frequent spikes and dips, suggesting that terrain naturally allows for recovery during descents, enabling sustained effort without constant heart rate control. Kirk counters that while heart rate can be less rigidly monitored on trails, it's still crucial for most runners, especially for fueling and avoiding gastrointestinal shutdown. He emphasizes that only highly skilled, well-trained athletes with strong downhill technique and recovery capacity can safely use this 'on-off' strategy. Both agree the approach is risky and not suitable for beginners, but could be a breakthrough tactic for experienced runners plateauing in performance. The discussion highlights the importance of individualization, skill, and experimentation in long-distance racing strategy. The hosts explore the concept of 'over-under' pacing—alternating between effort and recovery—drawing parallels to interval training and real-world race examples. They acknowledge that while steady-state pacing is safer and more predictable, terrain-based racing inherently creates built-in recovery periods. However, they caution that this strategy has a hard limit, likely around 50K, and that fueling, fatigue, and terrain mastery are critical factors. The episode concludes with a call to action: runners should experiment with different pacing styles in training to discover what works best for their physiology and skill level, rather than blindly following heart rate zones.