If you've landed here, your running has probably gone off (tired legs, slower times, no real energy...) and you're wondering whether you've overtrained.
Maybe you have. But the same symptoms often come from something more everyday: too little sleep, not eating enough to fuel your training, a stressful patch at work, or simply building your mileage up too quickly. That's under-recovery rather than overtraining, and it clears up far faster. The tricky part is that the two feel identical from the inside — so here are the five signs that tell them apart.
Sign 1: Your recovery starts dragging
Some soreness the day or two after a hard session (DOMS) is normal, even for elites. The warning sign is when it stops clearing. If soreness is still hanging around three or four days later, or your easy runs suddenly feel unreasonably hard, your body is telling you the last block hasn't been absorbed yet.
If soreness spills into daily life — you're stiff getting dressed, or feeling vaguely fluey and wrung out — that's your cue to back off until it settles, not to train through it.
Sign 2: Your pace stalls or slips
A drop in performance, or simply no progress, is one of the most reliable markers. The odd flat day on the track means nothing. But if the flatness persists for a couple of weeks despite decent rest and fuelling, take it seriously.
The instinctive response — add more sessions to "train through" the plateau — is exactly backwards. It deepens the hole. Fitness is built when you recover from training, not during it.
Sign 3: Niggles and injuries start multiplying
Under chronic fatigue, your body is in a permanently weakened, under-repaired state, so small tweaks appear more often and take longer to clear. One niggle becomes another, and suddenly you're playing whack-a-mole with your own legs. A runner who's constantly picking up minor injuries is usually either under-recovered or accumulating more load than their body can process.
This is the one place where what's on your feet genuinely matters — because a real chunk of a runner's total load is pure mechanical impact, and that's the part you can actually dampen. Taking some of the pounding out of each stride lowers the overuse-injury risk that so often tips runners into the hole, which is the logic behind a shock-absorbing insole. Enertor's PX1 running insoles, for instance, are clinically shown to absorb 51% of impact and cut injury risk by 66%. The brand matters far less than the principle, though: no insole makes up for missed rest or poor fuelling, but if repetitive impact is part of your load, softening it out of every step gives your recovery less to mop up.
Sign 4: Your mood and motivation dip
This is where overtraining stops being purely physical. Watch for irritability, low mood, anxiety, and a motivation to run that quietly evaporates. For people who use running as their release valve, that flatness is easy to miss and easy to dismiss. Don't — mood is often one of the earliest warning lights, ahead of the physical ones.
Sign 5: Your sleep gets worse
It sounds backwards, but training too hard wrecks sleep. Chronic overload raises your stress-hormone output, and that hormonal noise makes it harder to fall and stay asleep — right when you need sleep most, because it's your single biggest recovery tool. Worse sleep then amplifies every other sign on this list, which is how runners spiral downwards without spotting it.
The driver almost everyone misses: under-fuelling
Here's the piece the classic "signs of overtraining" article always skips. A huge proportion of what looks like overtraining is actually under-fuelling — not eating enough to support your training, known as low energy availability or RED-S.
Run consistently on too little fuel (especially too few carbohydrates) and you get the exact same picture: flat legs, stalled performance, poor recovery, low mood, disrupted sleep, more injuries. Studies have shown that simply raising carbohydrate intake can reverse overreaching symptoms. Before you assume you've trained too much, honestly ask whether you've fuelled too little. It's often the real culprit.
How to actually check it (not just guess)
You don't need lab tests. Two simple habits catch most overload early:
- Morning resting heart rate. Take your pulse (or read it off a watch) first thing, before you get up. Track it for a few weeks to learn your baseline. A rise of roughly 5–10 bpm that sticks around for several days is a classic "not recovered" signal. If your device shows heart-rate variability (HRV), a sustained drop points the same way.
- A ten-second wellness log. Each day, jot down how hard training felt (rate of perceived exertion) and how you feel overall — energised, flat, sore, irritable. Over time the patterns jump out. Easy runs feeling hard plus a grumpy mood is a reliable early flag.
One caution: wearables are wellness gadgets, not medical devices. Use them to support how you feel, never to override it. If something feels off, ease back even if your watch says you're "green."
What to do about it
Whatever the label, the fix rhymes:
- Back off before you have to. A few genuinely easy days, or a planned down week, is not lost fitness — it's when the fitness actually lands. Cut volume and intensity, don't just swap one for the other.
- Protect sleep first. It's the single highest-value recovery tool you have. Everything else works better on the back of it.
- Fuel the work you're doing. Enough overall energy, and enough carbohydrate around hard sessions. If you've been skimping, this alone can turn things around.
- Count all your stress. Work deadlines and bad sleep draw from the same recovery account as your long run. In a heavy life week, train lighter.
When it's more than overreaching
If you back off properly and things come good within a week or two, that was overreaching — normal, and now behind you. If they don't, don't keep guessing. Symptoms that drag on for weeks despite real rest, or come with things like ongoing weight loss, missed periods, persistent illness or a resting heart rate that won't settle, deserve a proper look from a sports doctor. Overtraining syndrome is diagnosed by ruling out other causes — low iron, thyroid issues, RED-S, illness — so getting checked is how you get answers, not an overreaction.
The short version
- Most "overtraining" is really overreaching or under-recovery — fixable in days to weeks.
- Watch for lingering soreness, a stalled pace, multiplying niggles, and dips in sleep, mood and motivation.
- Track morning resting heart rate and a quick daily wellness note to catch it early.
- Before blaming the miles, check you're fuelling enough — under-eating mimics overtraining exactly.
- The fix is recovery, not more work: back off, sleep, fuel, and manage total life stress.
- Dampening impact (through cushioning and good footwear) lightens the mechanical share of your load — a support act, never a substitute for rest.
- If it drags on for weeks despite rest, see a sports doctor.