How to tell if you're recovered enough to sprint

Is there a CNS fatigue test?

Coaches have long assumed that sprinting, heavy lifting and maximal jumps fry the central nervous system, and spaced those sessions 48 hours apart for that reason. A 2018 study tested the idea directly. Ten athletes did heavy squats, jump squats or 15 × 30m sprints, and the researchers used electrical and magnetic stimulation to measure the brain's drive to the muscle and the muscle's own force over the next three days.

After the sprints, the fatigue took 72 hours to resolve. The muscle's force stayed down for 48 hours, while the drop in voluntary activation, the part coming from the nervous system, lasted only 24. The authors concluded that this fatigue was not mainly a CNS problem. The 48-hour spacing still holds up, and the reason sits mostly in your legs.

A true CNS measure takes lab equipment. At home you can test your overall neuromuscular output, and the jump is a well-studied way to do it.

Jump tests (CMJ)

The countermovement jump (CMJ) is a standing vertical jump with a quick dip. It is a common field test for fatigue, and a meta-analysis of 151 studies that used it to track training found the average height of several jumps picked up fatigue better than your best jump did.

It works for sprinters. In a study of high-level sprinters running sets of 60m, the loss of CMJ height during the session tracked blood lactate and ammonia almost perfectly (r = 0.91 for both). Losses in sprint speed tracked them closely too.

Jump height has a blind spot. In a study that ran athletes through a fatiguing running protocol, most jump measures were back near baseline after 24 hours, but timing measures from a force plate were still changed at 72 hours. Your height can come back before the way you produce it does.

To use it, do a few jumps at the same point in the same warm-up each time, average them, and compare against your usual number. A drop bigger than your normal day-to-day variation is worth acting on.

HRV and resting heart rate

Heart rate variability (HRV) is the beat-to-beat variation in your heart rate at rest, and it reflects parasympathetic, or "rest and digest," activity. A review of heart-rate monitoring named short resting recordings taken almost daily among the most useful tools, as long as you judge each change against the measurement's normal error and your training context. It also warns that heart rate can't show every kind of fatigue, and suggests pairing it with training logs, questionnaires and a jump test.

Single readings mislead. In elite endurance athletes, both rises and falls in HRV have been linked to poor adaptation, and HRV sometimes falls while fitness improves. The fix is to use a rolling average and learn your own pattern over weeks. A meta-analysis of HRV-guided training, mostly in endurance athletes, found it kept HRV higher and produced fewer negative responses than fixed plans, with only small, non-significant advantages for fitness and performance.

Sleep

A 2021 expert consensus on athlete sleep found that a night or more without sleep reduces performance, while the effect of one to three nights of partial sleep restriction is still unclear. A separate review noted that some maximal efforts hold up after sleep loss even when sport-specific performance drops. The consensus recommends planning around your own sleep need rather than a fixed 7–9 hours.

Sleeping more over several weeks has helped. When Stanford basketball players aimed for at least 10 hours in bed for 5–7 weeks, they slept about 111 minutes more a night and their timed sprint dropped from 16.2 to 15.5 seconds. One short night is a reason to keep an eye on your warm-up. A week of them is a reason to cut volume.

Session RPE and how you feel

Session RPE is a training log you can keep in a notes app. After each session, rate how hard it was from 0 (rest) to 10 (maximal) and multiply by its length in minutes. A review of the method found it valid and reliable across sports, ages and levels, and summing it over a week shows when your load has jumped.

How you feel counts as data. A systematic review of 56 studies found that self-reported measures such as mood and perceived stress responded to training load more sensitively and consistently than objective measures like blood markers and heart rate. Subjective well-being dropped when load rose and improved when it fell, so a short morning check-in deserves a place next to the numbers from your watch.

Soreness

Delayed onset muscle soreness (DOMS) comes mostly from eccentric work and from exercises you aren't used to, and it is most common at the start of a season. A review found it can reduce range of motion, shock absorption and peak force, and that the changes in how you move to protect a sore muscle may raise injury risk if you return to full effort too soon. It advises cutting the intensity and duration of training for one to two days after a session that leaves you very sore.

Heavy soreness in the muscles you sprint with is a reason to follow that advice and shorten the session. Pain that feels sharp or sits in one spot is a different problem, covered in the safety note below.

A daily readiness check

Each marker answers a different question, so use them together.

In the morning, check your HRV or resting heart rate, your sleep and how you feel. At the track, do your usual sprint warm-up, add a few jumps, and time a primer sprint if you can. When one marker is off and the rest look normal, train as planned and watch it. When several point the same way, keep the session's speed and cut its volume, and if your times keep falling across a set, end it there.

A run of poor mornings across a week usually means you need lighter training for longer. The deload week guide covers how to plan one, and speed training explains how high and low days are spaced.