What exactly is HRV and why measure it?
HRV refers to the variation in time intervals between heartbeats. While measuring HRV is easy with a smartwatch, interpreting it can be tricky. Cyclists track HRV because it indicates how well their body is recovering from training and adapting to stress, providing insight into their readiness to perform. But is high HRV always good and low always bad?
Interpreting high HRV
Generally, a high HRV reading suggests your body is recovered, well-rested, and ready for training. Studies show that endurance athletes often achieve better fitness gains when they train harder on days when their HRV is high or within baseline ranges. This has led to the belief that higher HRV scores indicate improved fitness or positive training adaptations.
However, seeing a consistent high HRV isn’t always beneficial. For endurance cyclists, prolonged increases in HRV might even signal overtraining, particularly during high-volume training blocks. A study involving elite triathletes found that increasing HRV trends accompanied performance declines due to overreaching. This shows that a continuously rising HRV isn’t always a positive sign.
Interpreting low HRV
Low HRV scores typically reflect acute fatigue from recent intense training or competition. Intense cycling sessions or races often temporarily reduce HRV as your body recovers. However, it’s crucial to recognise that low HRV doesn’t necessarily predict poor performance. Research has shown that athletes can achieve personal bests and maintain strong performances despite low HRV readings on the day of competition. The explanation for the drop in HRV could be pre-competition anxiety or excitement.
This suggests that transient decreases might actually signify an athlete’s readiness to perform at high intensity rather than fatigue.
When HRV trends might be misleading
Interestingly, seeing a decreasing HRV trend isn’t always problematic. High-intensity interval training and anaerobic workouts commonly lower HRV, even without substantial fatigue buildup. For example, a study shows that elite rowers experienced reduced HRV during intense anaerobic training phases, yet their performances remained strong. Simply put, if your training cycle includes a lot of high-intensity intervals, declining HRV doesn’t necessarily signal poor recovery or reduced performance capacity.
Similarly, incorporating moderate aerobic cycling sessions can artificially elevate HRV, masking underlying fatigue. Removing these sessions might decrease HRV again, not because of increased fatigue, but due to shifting training types. All this is to say that the context of your training is critical when interpreting HRV.
Practical tips for reading HRV
Hopefully, this article showed that the simplistic “high equals good, low equals bad” isn’t enough to sensibly interpret your HRV. Always consider your HRV readings within the broader context of your training regimen, recovery, and lifestyle.
Don’t overinterpret daily fluctuations: Understand that temporary changes can reflect excitement, anxiety or recent intense sessions, not necessarily chronic fatigue.
Look at patterns in context: When you see a rising or falling HRV over weeks, consider how your training load and type have changed during that period before making conclusions.
Consider lifestyle factors: Sleep quality, nutrition, and stress significantly influence HRV.
Adjust training thoughtfully: Always use HRV trends alongside subjective feelings of fatigue and performance data to make informed decisions.
