Signs You’re Overdoing Cardio

Cardio has a well-earned reputation for protecting heart health, boosting mood and improving fitness. But more isn’t always better. While regular cardio is one of the healthiest habits you can build, overdoing it can quietly work against your body rather than for it.

Many people miss the early warning signs because they assume feeling exhausted, sore or drained is simply “part of being fit.” In reality, your body often sends clear signals when it needs balance, not more mileage.

So, how do you know when cardio is helping — and when you might be pushing too far?

Why Too Much Cardio Can Be a Problem

Cardio is a stressor. In the right dose, it strengthens the heart and improves resilience. In excess, especially without adequate recovery or strength work, it can lead to fatigue, hormonal disruption, injury and stalled progress.

This is particularly common among people who:

Exercise daily without rest days
Rely only on cardio and skip strength training
Train intensely while under stress or sleeping poorly
Believe weight loss or heart health requires “more and more” cardio

Understanding the signs early can prevent burnout and long-term setbacks.

Common Signs You’re Overdoing Cardio

1. Constant Fatigue That Doesn’t Improve With Rest

Feeling tired after a workout is normal. Feeling exhausted most of the day — even after sleep — is not. Persistent fatigue can signal that your body isn’t recovering between sessions.

If your energy keeps dropping despite staying active, it may be time to reduce intensity or frequency.

2. Declining Performance

If workouts that once felt manageable suddenly feel harder, slower or more draining, your body may be overstressed. Overdoing cardio can actually reduce endurance over time instead of improving it.

Plateaus or regressions are often a sign that recovery is missing.

3. Frequent Aches, Pains or Injuries

Nagging joint pain, shin splints, knee discomfort or recurring muscle strains are common signs of repetitive overload — especially with high-impact cardio like running.

When pain becomes a regular companion, your body is asking for variety and support, not more repetition.

4. Trouble Sleeping or Restless Nights

Ironically, too much cardio can interfere with sleep. Elevated stress hormones can make it harder to fall asleep or stay asleep, even when you feel physically tired.

Poor sleep then compounds the problem by slowing recovery further.

5. Mood Changes and Irritability

Exercise usually improves mood, but excessive cardio can have the opposite effect. Irritability, low motivation, anxiety or feeling unusually flat can all be signs of overtraining.

Your nervous system needs recovery just as much as your muscles do.

6. Increased Hunger or Loss of Appetite

Overdoing cardio can disrupt appetite signals. Some people feel constantly hungry and struggle with cravings, while others lose appetite altogether. Both can indicate stress on the body.

This can make weight management harder rather than easier.

7. Your Heart Rate Stays Elevated

If your resting heart rate is consistently higher than usual, or your heart rate takes longer to recover after workouts, this may indicate accumulated fatigue.

These are subtle but important signs that your cardiovascular system needs rest.

How Much Cardio Is Actually Enough?

This is where perspective helps. As we explored in How Much Cardio Do You Really Need for Heart Health?, most adults benefit from about 150 minutes of moderate-intensity cardio per week.

Doing more can add benefits — but only when balanced with recovery and other forms of movement.

Cardio works best as part of a broader approach, not as the only tool.

What to Do Instead: Find the Balance

If you recognise several of the signs above, it doesn’t mean cardio is bad — it means your routine needs adjustment.

Helpful strategies include:

Reducing cardio frequency or intensity for a short period
Adding rest or active recovery days
Mixing high-impact cardio with low-impact options like walking or cycling
Incorporating strength training to support joints, metabolism and heart health

Strength-based exercise is especially important. As discussed in The Longevity Workout: How Strength Training Slows Ageing and Protects Your Health, building muscle improves cardiovascular efficiency and reduces overall strain on the heart.

Listen to Progress, Not Pressure

Healthy cardio should leave you feeling more energised over time, not constantly depleted. The goal isn’t to do the most — it’s to do what your body can adapt to and sustain.

If your routine supports better sleep, steady energy, improved mood and resilience, you’re on the right track.

The Bottom Line

Cardio is one of the best things you can do for your heart — but overdoing it can quietly undermine your health. Fatigue, poor sleep, mood changes and recurring pain are not signs of commitment; they’re signals to rebalance.

The healthiest routine blends cardio, strength, recovery and rest — and evolves with your body over time.

What’s Your Take?

Have you ever felt burnt out from doing “too much” cardio? What helped you restore balance? Share your experience — it could help someone else listen to their body sooner.