A regular exercise program can help to prevent disease and to prolong lives, but every serious exerciser learns sooner or later that exercising too much can cause injuries and health issues. A recent study from Austria reports that emotional symptoms can often be an early sign that a person is exercising too much: restlessness, mood changes, irritability, emotional instability, recurring states of fear, emerging indifference and reduced performance motivation (Dtsch Z Sportmed, Oct 2021;72(6):271-279).

In an earlier study, elite athletes were instructed to over-train for three out of nine weeks, and were then compared to a group who did a normal nine-week training program (Current Biology, September 26, 2019). Not only did the over-trained athletes perform worse on endurance tests, their brains were affected as well as their muscles and other body functions. The overworked athletes suffered from mental symptoms including depression, irritability, restlessness, insomnia, and loss of appetite. They also made poor decisions in tests such as choosing meager immediate personal rewards over more substantial delayed rewards (i.e., taking $10 now rather than $50 in six months). fMRIs of their brains showed reduced activity of the lateral prefrontal cortex, a key region in which a person makes important decisions.

Signs of Over-Training
A regular exercise program is supposed to make you feel good, increase your energy level and help to control your weight. You may be exercising too much if you have:
Quality-of-life signs of over-training: Lack of energy, increase in tension, depression, anger or confusion, inability to relax, poor-quality sleep, decreased motivation, moodiness, not feeling joy from things that were once enjoyable.
Health-related signs of over-training: Frequent colds, increased blood pressure or resting heart rate, irregular menstrual cycles or missed periods, unintended weight loss, loss of appetite, constipation, diarrhea.
Signs of an impending injury: Muscle soreness on one side of your body or localized pain on one side, unusual soreness after a workout, inability to train or compete at a previously manageable level, delays in recovery from workouts.

My Personal History of Over-Training
Athletes train by stressing and recovering. You make a muscle stronger by stressing that muscle, feeling sore on the next day, and taking easy workouts or days off until the soreness goes away. Then you are supposed to take a hard workout again. If you do not feel muscle soreness on the day after a hard workout, you have not injured your muscles and they will not become stronger. Sometimes your muscles still feel a little sore several days after a hard workout, but you think that you have recovered and are ready to stress your muscles again, so you go ahead and try to run very fast. You start to feel sore all the time, your joints, muscles and tendons ache, and you feel tired. You can still run with the soreness in your muscles and tendons, but the soreness prevents you from running fast. Each succeeding day, the soreness increases and you think that you are sick.

This happened to me when I was training for a marathon, so I ordered tests including a complete blood count, liver tests, BUN, creatinine, urinalysis, and a throat culture, but all the results were normal. I couldn’t run my intervals as fast as usual. I had been able to run 10 quarters in 65 seconds and now I couldn’t get through more than three of them without my muscles feeling very sore. I knew something was wrong, so I asked a friend who was a researcher at a nearby university to test me. He told me that I had impaired anaerobic lactic acid clearance and a reduced time-to-exhaustion in standardized high-intensity endurance exercise tests. My maximum heart rate was 10 beats lower than normal, my lactate levels were lowered during sub-maximal performance, and I had a reduced respiratory exchange ratio during exercise. By now I was quite depressed, so I got further tests and decided I might have a hidden lymphoma, but my complete diagnostic workup was normal. I was stuck with a diagnosis of training too much.

Recovery from Over-Training
When you are suffering from over-training, you need to go back to background work. These principles apply to any sport. For a runner, jog on the days that you can. Take days off when you feel sore. After several weeks, you are able to start regular jogging and your muscles feel fresh again. When this happens, you are ready to start training, but first you must promise yourself that you will never try to run fast when you feel soreness in your muscles and tendons. Set up a schedule in which you take a hard-fast workout, feel sore on the next day, and then go at an easy pace in your workouts until the soreness has completely disappeared. You may set up a schedule to try to take a hard workout every third or fourth day, but you will skip a hard workout on any day that you feel sore.

Most runners plan to run very fast once a week and long once a week. You recover faster from a hard workout by doing nothing, but jogging slowly on recovery days causes more fibrous tissue to form in your muscles so that they are more resistant to injury. Don’t calculate total miles per week in your diary; that will encourage you to pile up junk miles and prevent you from learning how to run fast. You can run in races only as fast as your fastest workout intervals. Set up a program in which you run very fast on Wednesdays and long and brisk on Sundays, and make all your other workouts easy recovery ones.

Competitive runners usually use interval workouts to increase their speed. When you have recovered from overuse syndrome, you should start with short intervals before you try longer ones. For example, you could start with 110 yard intervals. Mark the track in quarters, using the fifty yard lines and the middle of the goal posts. Alternate running 110 yards fast and comfortably, and jogging 110 yards until your legs start to feel heavy and stiff. When you can run at last 20 repetitions of 110 yards fairly fast, try doing repeat 220s, and as the weeks progress, work up to repeat half miles. Don’t try to run through the stiffness or you will take weeks to recover. If your legs are exceptionally sore, take the next day off. If they are not sore, jog easily on the next two or three days.

Use your Sunday workouts to try to gain endurance. Your endurance day should not be as fast as your interval day. Each Sunday, try to work up to where you can run fairly fast for up to two hours. You may have to start out with a long run of only 30 minutes, but be patient. Lack of patience can lead to overtraining syndrome. You should eventually be able to learn how to train without injuring yourself and avoid making the same overtraining mistakes again.

My Recommendations
I believe that all regular exercisers should set up a program in which they exercise a little more intensely on one day, feel sore on the next day and go easy for as many days as it takes for them to feel fresh again. They should take the day off if they feel local tenderness in one muscle group that does not go away when they stop or slow down. If they develop symptoms of overtraining, they may need to check with a doctor or seek out a knowledgeable coach in their sport.