If you're someone who trains hard, trains often, and tells people about it, you’re sure to hear the warning, “Don’t overdo it. You don’t want to overtrain.” 

The idea expressed there is that if you train too much, too hard, you’ll actually see worse results – less muscle, loss of endurance, and it might even make you sick. Maybe you’ve taken that warning to heart, or maybe not. In either case, you’re probably a little unclear on just how big of an issue overtraining is. And how will you know if you get there? The answer is complicated – it’s actually three different issues altogether. 

How to Know If You're Overtraining

Local Versus Systemic Recovery

First off, there are two types of fatigue and recovery you might experience after or between workouts: local and systemic.

Local fatigue is specific to a muscle. Do squats and your quads and glutes get fatigued, and they might need a couple of days to fully recover. Run for an hour, and your calves might take a day to bounce back. Local fatigue happens because muscles get drained of glycogen, metabolic byproducts like lactic acid and ammonia build up in them, and they suffer micro-tears and protein catabolism. There is where repair time comes in.  

Systemic fatigue is not muscle-specific. It includes a variety of mechanisms: Cardiovascular stress, hormonal balance (testosterone/cortisol ration in particular), liver glycogen depletion, and fatigue in the parts of the brain that control attention and wakefulness. The section of the central nervous system that directly controls your muscles may also experience weariness, though – contrary to popular belief – this only lasts for tens of minutes, not days.

In general, resistance training produces primarily local fatigue. In other words, the specific muscles you worked get worn out and need time off. Resistance training does affect hormonal parameters such as T/C ratio, but it would take a large volume of full-body training for this to begin to rival local fatigue as a limiting factor. Cardiovascular exercise, on the other hand, produces greater amounts of systemic – particularly cardiovascular – fatigue. Recovery from cardio tends to be mostly systemic.

Related: Use a Band to Accommodate Resistance Training Exercises For Safer Sets & Greater Gains

But there's one exception here: forms of cardio that you’re totally new at. If you just recently started running, you may have noticed that your calves give out before you even feel like you need to stop because you’re tired.  However, for most forms of cardio and for most people, this only lasts 1-3 months before systemic fatigue replaces local as the limiting factor.

Overtraining or Overreaching: Which Is It?

While the term overtraining is often used literally to mean training too much, it actually has a more specific definition in exercise science and is contrasted with overreaching.

Overreaching is a state in which the body is fatigued beyond its capacity to quickly recover. When you overreach, you’ll notice that you stop making progress – your strength and endurance plateau. You may also feel tired, cranky, and notice you don’t sleep as well. In that case, you’re experiencing systemic overreaching.  If you notice a lack of progress but no outstanding effects on your quality of life, that’s local overreaching. 

Overreaching is temporary and relatively mild. All it takes is a de-load week (a week in which you train about half as much, and at lower intensity) to get over it. Overtraining syndrome is much more serious. If you keep pushing yourself beyond the point of systemic overreaching, you may reach a state of chronic, extreme fatigue as the body is stressed beyond its capacity to recover. The symptoms of overtraining to watch for are:

• Low resting heart rate
• Low blood pressure
• Depression
• Increased tiredness
• Easy onset of fatigue when starting exercise
• Sleepiness and drowsiness
• Hypoglycemia (low blood sugar) and depressed immune system
• Low testosterone and high cortisol
• Inability to concentrate
• A loss of interest in training
• Loss of muscle mass
  
  

The bad news is that once you get to this stage, you need to take more drastic measures. A week of light exercise won’t do it: You may need 2-3 weeks of very minimal exercise. That doesn’t mean no exercise, but it means very light, active recovery workouts. 

Related: 5 Signs You’re Overtraining (and 5 Antidotes)

The GOOD news is that overtraining tends to be self-limiting. It causes you to not want to exercise, so it tends to only be a problem for intensely-motivated trainees. Generally these trainees are one of two people: athletes with coaches who push them to overtrain, and/or people who abuse stimulants to push themselves further even when their body needs rest. 

Basically, there are three things that can happen: local overreaching, systemic overreaching, and systemic overtraining syndrome. Because overtraining inherently involves system factors, there isn’t really such a thing as local overtraining syndrome. 

Local Overreaching and Optimal Resistance Training Volume

So how do you determine how much is too much? Training volume for resistance exercise is best measured in terms of sets per workout and per week.

When we're talking weekly volume, the optimum is higher than most people realize. For experienced trainees who get great nutrition and sleep, it may even exceed 30 sets per muscle group per week. Yes, you read that right. In fact, in very advanced trainees, some slow-twitch-dominant muscles, such as the quadriceps, may benefit from as many as 45 sets per week.

That said, this is unique and specific to the targeted muscle, the trainee, and any external circumstances that might affect your performance. You might recover great today, but not so well when work gets crazy and you’re stressed out and exhausted. 

Related: Why This Should Be Your #1 Workout Strategy to Avoid Overtraining

Ultimately, the best way to judge local recovery is to record all of your workouts and constantly check that you’re making progress. Not every lift will drastically increase every workout, of course, but if you find that a given lift or muscle group has plateaued for 2-3 workouts, that muscle might need more rest. Then again, it might just need more volume. 

If you find yourself in this situation, try this: Give just that individual muscle group a de-load week. (No, de-loads don’t need to be full-body.) If that doesn’t work, try upping the volume for that muscle or working on your form. And, if you find most or all of your muscles plateauing at the same time, look for signs of systemic overreaching. 

Systemic Overtraining and Optimal Cardio Volume

Overtraining is usually assessed with a variety of blood tests that examine markers of stress, inflammation, and muscle protein turnover.  However, this isn’t very practical in real life. 

As with local overreaching, systemic overreaching is easiest to catch early if you’re tracking your progress. If you’re doing cardio, time your runs or your average pace – whatever metric you’re using. You can track health parameters using a fitness tracker. Look for one that measures sleep (not just total sleep time, but REM and deep sleep) as well as heart rate variability and resting heart rate. 

More subjective parameters, including overall subjective well-being, can be tracked with apps like Daylio, which allows you to record and track the correlations between what you do on any given day, how well you slept, and how good your day was. When in doubt, eat more vegetables and fruits, cut out alcohol and caffeine, and get an extra hour of sleep. 

Related: Top Post-Workout Power Meals to Fuel Up & Recover Faster

While you don’t want to overstress your body, you also don’t want to use overtraining as an excuse to slack off. There will be days when you feel tired or just really don’t want to work out. When that happens (and it will), work out anyway – just keep a careful eye on your performance. 

If you’re still progressing, you can ignore your lack of motivation and push yourself through it. However, if you feel crappy and objective measures show that you’re losing strength and stamina — and your resting heart rate and heart rate variability are getting worse — TAKE THE HINT! Don’t force yourself to overload your body even further, and especially don’t abuse caffeine and pre-workout formulas to push through the exhaustion and train harder. That’s how you turn overreaching into overtraining.