Exercise, Recovery & Readiness

Heart rate and HRV (heart rate variability) can change around exercise. HRV, however, is not a direct measure of exercise recovery. Sleep, symptoms, breathing, posture, temperature, measurement time, and other conditions also affect it. This page explains the research on exercise and HRV, together with the limits that matter in everyday use.

Does exercise raise or lower HRV?

Group studies have reported a temporary fall in some HRV measures after hard exercise and later change over time (Plews et al., 2013). Meta-analysis has also associated regular aerobic exercise with an average rise in resting HRV (Sandercock et al., 2005). The size and direction vary by person, activity, and protocol, so one value cannot establish that you have recovered or that exercise “worked.”

Can HRV detect overtraining?

Monitoring training status through autonomic measures has been examined in systematic reviews (Bellenger et al., 2016). HRV alone cannot judge overload, though, and what a rise or fall means shifts with sleep, condition, temperature and stress (Plews et al., 2013). Read it as one clue, in the flow.

First, why is HRV related to exercise?

HRV describes variation in the interval between heartbeats. Under controlled resting conditions, some short-term HRV measures are often interpreted as reflecting cardiac parasympathetic modulation. HRV as a whole is not a direct window onto your body's condition or a simple balance between sympathetic and parasympathetic activity.

For more, please also see What is HRV?.

Can regular exercise change HRV?

Meta-analysis has reported that some resting HRV measures increased on average after regular aerobic exercise (Sandercock et al., 2005). This group-average result does not mean that everyone will change in the same way or that a rise in HRV alone confirms a health benefit.

Rather than chasing each day's score with highs and lows, this is a change that comes into view when you gaze slowly over a long yardstick of several weeks to several months. Nothing is decided in a single day, so we hope you can read it with your shoulders relaxed.

How HRV changes after exercise

Some studies report that HRV temporarily falls after hard exercise and changes over the following hours or days. Athletes therefore sometimes use it as one clue when monitoring training status (Plews et al., 2013). The speed of return to a previous value does not necessarily equal degree of recovery, and HRV alone cannot prescribe training volume.

Figure: a schematic example in which overnight HRV falls after exercise and later changes. The dotted line is a personal baseline. Not everyone follows this curve, and the figure does not directly represent recovery.

How to read these ups and downs

• HRV may fall after exercise, but it may not. Neither result is, by itself, evidence that the response was good or bad.
• The speed of return to a usual range is one possible clue, not a direct measure of completed recovery or required rest. Consider perceived fatigue, soreness, sleep, resting heart rate, and symptoms as well.
• The method of monitoring exercise status with autonomic indicators has also been examined in systematic review and meta-analysis (Bellenger et al., 2016).
• Records from your own past under reasonably similar conditions can provide more context than a single value. Even so, the meaning of a rise or fall changes with sleep, symptoms, temperature, stress, and other factors (Plews et al., 2013). Do not judge from one number.

How Feelmo handles it

Feelmo compares available HRV-derived information with patterns in your own past records. It does not directly measure emotion, autonomic function, fatigue, recovery, or how “settled” your body is.

Feelmo may separately summarize an observational association between habit records you logged, such as exercise, and Balance (0–100). Proprietary processing details are not public, and the display does not prove a causal effect.

How Balance works

• It uses proprietary on-device processing to summarize HRV-derived information available through Apple Watch / HealthKit and patterns in your own past.
• Processing and display rules are not public.
• Higher and lower do not establish medical normality or recovery from exercise.
• Do not compete with other people's values; cautiously compare your own records collected under reasonably similar conditions.

For more, please see Balance score and The idea of a baseline.

The six companions are product characters

Feelmo uses six product interface characters (Genki, Odayaka, Futsuu, Fuan, Panku, and Tsukare). Their display rules are not public. A “Tsukare” display after exercise does not mean that fatigue or inadequate recovery was detected. Decide whether to change a workout from your actual symptoms, fatigue, sleep, and circumstances—not from the character alone (The 6 Companions).

Comparing associations in your own records

Feelmo Premium's Habit association patterns summarize observational relationships between exercise or breathing records and Balance. Proprietary processing details are not public, and the display does not prove an effect or causal relationship (Details).

Detailed proprietary processing and display rules are not public. Treat Balance as product-specific reference information, not a measure of health or recovery.

Here's how you can use it

1. Exercise as usual, and at night sleep with your Apple Watch on.
2. The next morning, gaze at the balance gauge and the 6 expressions on the home screen.
3. Do not choose a workout from the face label alone; check your actual fatigue, pain, sleep, and other symptoms.
4. Using the records you have, review how exercise days line up with HRV and Balance. A pattern seen in the chart is still an association, not proof that exercise caused it (Feelmo Premium).

Not to push you, but to help you settle. Not to be tossed around by numbers, but to grow friendly with your own rhythm — that is Feelmo's wish.

References

1. Sandercock GR, Bromley PD, Brodie DA. Effects of exercise on heart rate variability: inferences from meta-analysis. Medicine & Science in Sports & Exercise. 2005;37(3):433–439.
2. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine. 2013;43(9):773–781.
3. Bellenger CR, Fuller JT, Thomson RL, Davison K, Robertson EY, Buckley JD. Monitoring Athletic Training Status Through Autonomic Heart Rate Regulation: A Systematic Review and Meta-Analysis. Sports Medicine. 2016;46(10):1461–1486.