10 Signs You're About to Overtrain (And Don't Even Know It)

December 10, 2025

Every runner knows the feeling of productive fatigue—that satisfying heaviness after a hard workout that disappears with rest. But what happens when it doesn't disappear? When your easy runs stay hard, your mood tanks, and your motivation evaporates despite doing everything your training plan demands?

The gap between "pushing hard" and "pushing too hard" is thinner than most runners realize. Worse, crossing it doesn't feel like crossing anything at all—you're already overtrained before you understand what's happening.

In this article, you'll learn to recognize the ten early warning signs while there's still time to back off.

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What is overtraining?

Overtraining happens when training stress exceeds your body's ability to recover. In simple words, you're breaking down faster than you're building back up.

There's a difference between functional overreaching—pushing hard for a few weeks before recovering—and overtraining syndrome, which can sideline you for months.

Overtraining develops gradually, not overnight. Serious runners face the highest risk because they have the discipline to keep pushing through signals that something's wrong.

Let’s break down the ten signals that separate productive training stress from destructive overtraining:

1. Your resting heart rate is climbing

Check your heart rate first thing in the morning, before you get out of bed. Do this for a week to establish your baseline. Most runners sit between 40-60 beats per minute.

Now watch for drift. If your resting heart rate climbs 5-10 beats above baseline and stays there for several days, your nervous system is struggling.

An overtrained runner might see their usual 48 bpm climb to 58 bpm. That's your body telling you it hasn't recovered from yesterday's workout, or last week's workouts, or last month's training block.

Track this in a notebook or your watch app. When the number creeps up, ease back before your body forces you to stop.

2. You're sleeping worse

You ran intervals today. You should sleep like the dead. Instead, you're staring at the ceiling at 2 a.m., legs twitching, mind racing through tomorrow's workout splits.

Chronic training stress floods your system with cortisol. This stress hormone peaks when it should drop, keeping you wired when you need rest. You might fall asleep from exhaustion, then wake repeatedly. Or lie down exhausted but unable to shut off your brain.

When hard training improves sleep, you're adapting well. When it disrupts sleep, you're overdoing it.

3. Your legs feel heavy every run

You know that sensation three days after a hard marathon—legs full of concrete, each step pulling you down? Now imagine that feeling on a Tuesday morning easy run.

Persistent muscle heaviness means your legs never fully recover between sessions. The micro-damage from training accumulates faster than your body repairs it. Normal soreness fades 24-48 hours after a hard effort, overtraining soreness doesn't— it just shifts from muscle to muscle.

4. Your easy pace feels hard

Your easy pace should be conversational: you could maintain a full sentence without gasping. Maybe that's 9:00 per mile (5:35 per km) for you, maybe it's 11:00 per mile (6:50 per km). The specific pace doesn't matter.

What matters is when your usual easy effort suddenly feels like tempo effort. Your heart rate at 9:00 pace used to sit at 135 bpm. Now it's hitting 150 bpm at the same speed. This effort-to-pace disconnect is your body waving a red flag.

Recovery runs should feel easy. If they don't, you need better recovery.

5. You're getting sick more often

You've had three colds in two months. You caught whatever virus went around the office while everyone else stayed healthy. Heavy training suppresses your immune system for several hours after hard efforts. That's normal. What's not normal is staying in a constantly weakened state.

When you're overtraining, your body stays stuck in stress mode, leaving your immune defenses compromised. If you're reaching for pills more than your foam roller, your training load is too high.

6. Your mood is tanking

You snap at your partner over nothing. The idea of lacing up your shoes fills you with dread instead of excitement. You feel anxious, irritable, or flat-out depressed for no clear reason.

Overtraining stresses your muscles and cardiovascular system, but moreover, it hammers your nervous system and hormones. The same cortisol keeping you awake at night also messes with your mood regulation.

Notice when running stops being the part of your day that makes everything else better and becomes just another obligation you resent.

7. Your performance is plateauing or declining

When you're adapting well to training, fitness improves or holds steady. When you're overtraining, performance degrades. Your body can't produce the speed or power it used to because it's too busy trying to survive your training plan.

If your splits are moving in the wrong direction while your mileage climbs, stop adding volume.

8. You're always hungry or never hungry

Your appetite reflects your metabolic and hormonal state. Overtraining throws both into chaos.

Some runners become ravenous, eating everything in sight but never feeling satisfied. Others lose their appetite completely—the thought of breakfast makes them queasy. You might drop 5-7 pounds (2-3 kg) in two weeks despite no intentional diet changes.

When your eating patterns shift dramatically without explanation, your endocrine system is struggling under training stress. Your body is confused about whether to fuel or shut down.

9. Minor aches won't go away

Nothing hurts enough to stop you, but nothing fully heals either. Sound familiar?

Overtraining creates a state of chronic inflammation: your body constantly directs resources to damage control, never quite catching up.

What starts as one problem area multiplies into three or four simultaneously.

This is how overtraining becomes injury. Those persistent niggles are pre-injuries, waiting for one more hard workout to tip them over the edge.

10. You've lost your running joy

Remember why you started running? Maybe you loved the challenge. Maybe you just felt good moving your body. Now you're scrolling through your watch data with dread. Planning your week around workouts feels suffocating instead of exciting. You think about skipping your long run and feel relief instead of guilt.

Mental burnout often precedes physical burnout. When running shifts from something you want to do to something you have to do, you've crossed a line. The passion drain is real, and it's telling you to back off.

What to do if you recognize these signs

First, stop digging. Don't add mileage, don't add intensity, don't try to train through this. Take 3-7 full days completely off. Not easy running, not cross-training. Actual rest.

When you return, cut your weekly mileage by 50% for two weeks. If you were running 50 miles (80 km), drop to 25 miles (40 km). Just easy miles and recovery.

Prioritize sleep like it's part of your training—because it is. Aim for 8-9 hours per night. Dial in your nutrition. Consider working with a coach who can provide objective perspective when you can't.

If symptoms persist beyond two weeks of reduced training, see a sports medicine doctor. Overtraining syndrome can take months to resolve if you ignore it.

How to prevent overtraining

  • Cap weekly mileage increases at 10%. This is protection against your own enthusiasm. If you ran 40 miles (64 km) this week, don't jump to 50 miles (80 km) next week.

  • Schedule recovery weeks every fourth week. Drop to 60-70% of your peak volume before you're forced to stop. If your high weeks hit 50 miles (80 km), your recovery week should be 30-35 miles (48-56 km).

  • Learn the difference between productive discomfort and destructive stress. Productive discomfort feels hard during intervals but resolves with recovery. Destructive stress accumulates and compounds.

  • Track morning heart rate, sleep quality, and mood alongside your splits. These indicators often shift before your workouts suffer. When two or more trend wrong simultaneously, back off immediately.

  • Build rest days into your weekly plan. If you're running six days a week, that off day isn't negotiable.

Recognize these warning signs early and back off before it becomes mandatory. The best training plan is the one you can actually recover from.