Recovery monitoring: what the numbers can and cannot tell you

A great many people now wake up to a score telling them how recovered they are. Some of this is genuinely useful and some of it is a number generated from a proprietary algorithm applied to a noisy signal.

Heart rate variability

The metric underlying most readiness scores. HRV measures the variation in time between successive heartbeats, which reflects the balance between sympathetic and parasympathetic nervous system activity.

Higher HRV generally indicates greater parasympathetic influence, associated with a rested state. Lower HRV suggests sympathetic dominance, associated with stress, fatigue or illness.

The evidence for HRV tracking training status in endurance athletes is reasonably good. The evidence in resistance-trained populations is thinner and less consistent.

The problems with a single reading

Enormous day-to-day variability. HRV fluctuates with sleep position, measurement time, alcohol, caffeine, hydration, illness, breathing rate during measurement, and the phase of the menstrual cycle. A single low reading means very little.

Individual baselines differ hugely. Absolute values are not comparable between people. What matters is your own value relative to your own rolling baseline.

Direction is ambiguous. Very high HRV can indicate excellent recovery, and it can also occur in states of severe overreaching. The relationship is not monotonic.

Measurement quality varies. Chest straps and dedicated devices measuring on waking under standardised conditions produce far better data than an optical sensor on a wrist during sleep.

Using it properly if you use it

Measure consistently — same time, same conditions, ideally first thing on waking.

Use a rolling average over seven days rather than daily readings, and look at your value relative to your own normal range rather than at an absolute number.

Act on trends, not on single days. Several consecutive days of suppression, alongside other signals, is meaningful. One low morning is noise.

The simpler measures that work as well

Honestly, for most lifters, the following are at least as informative and cost nothing.

Resting heart rate. More stable than HRV, easier to measure, and an elevation of several beats above your normal over multiple days is a meaningful signal.

Sleep duration and quality. Tracked or simply noted.

Subjective wellness ratings. Rate sleep, fatigue, soreness, mood and stress out of five each morning. This takes ten seconds and, in the sports science literature, subjective measures often track training response as well as or better than physiological ones.

Performance itself. Warm-up weights feeling heavy is the single most informative recovery marker available. If your usual warm-up feels laboured for several sessions, that means more than any score.

Bar speed, if you have a velocity device or even a consistent subjective sense of it. Reduced velocity at a given load is a well-supported fatigue indicator.

The risk of over-monitoring

There is a real phenomenon of people being told by a device that they are unrecovered, and consequently having a worse session than they would have had without the information.

Expectation effects are powerful. A person who reads a poor readiness score and trains anyway frequently performs fine; the score influenced the expectation more than the physiology.

There is also the anxiety dimension. Some people find continuous monitoring genuinely stressful, and stress about recovery is not a good route to recovery.

What to actually do with the data

Use it to inform autoregulation, not to dictate it.

Several consecutive days of poor markers, alongside declining performance and poor subjective state, is a reason to reduce volume or take a deload. That is a sensible use.

A single low morning is not a reason to skip training. Go to the gym, warm up, and let the warm-up tell you. It is more reliable than the wrist.