The Cumulative Stress Effect in Overtraining Syndrome

Overtraining Syndrome is a state where an athlete has been repeatedly stressed by training to the point where rest is no longer adequate to allow for recovery and performance decreases. Overtraining has a strong physiological component which often includes changes in red blood cells that decrease oxygen carrying capacity, changes in hormones, and changes in immune function.

I work with many professional triathletes and a handful of cyclists and runners. A key component in being a medical adviser to them is monitoring for signs of overtraining syndrome (OS) and reacting as necessary to prevent OS. Once the physiological changes occur, it can take months for some people to recover.

For professional athletes, it is usually purely the physical stress that can induce OS. Many of them are training over 30 hours per week at intense levels. However, a very important fact to be aware of is that emotional stress can play a very big role in inducing OS. For age group athletes who are trying to juggle a full-time job, home life, and training, this becomes a very important aspect of their training. It is important to take emotional stress into consideration during your training, just as you do physical stress.

The physiological/biochemical effects of excess emotional stress on the body are not much different from the effects of excess physical stress. Hormones, organs, and various systems of the body are affected. One well-known hormone affected by stress is cortisol. Cortisol plays an important part in so many functions of the body on an everyday basis. Cortisol is also quite active during exercise.

During prolonged aerobic exercise, cortisol functions to preserve body carbohydrate stores. Cortisol increases alternate fuels for muscle, such as fatty acids and amino acids (from muscle amino acid stores and protein break down), impairs glucose entry into skeletal muscle, and supplies the fuels (amino acids) for the liver to increase glucose production. All these functions are increased during times of low body carbohydrate nutrition, such as when blood glucose decreases. In longer endurance events, utilizing alternate fuels for muscle is vital to success (see my blog post "Let the Tank Hit Empty").

Emotional stress causes the adrenal glands to release more cortisol. In the short term, this is of little concern, however if prolonged, the adrenal glands can become fatigued. Fatigued adrenal glands result in a decreased ability of the glands to respond to stress (physical or emotional). If the adrenal glands are unable to respond optimally to physical stress, performance will suffer, as your body will not be able to preserve carbohydrate stores adequately. The result...a bonk!

What Does This Mean?

It is important to factor in emotional/life stress into your training plan. If you are in a stressful job and life situation, high volume training may not be the best approach for you. You may want to stick to a coaching plan that focuses less on volume and more on key sessions. There are many very successful Ironman age group athletes out there that are only putting in 12-15 hours per week. There are many very successful Ironman 70.3 age group athletes putting in only 8 hours of training per week.

For some, myself included, exercise is our escape and higher volume training is well tolerated both physically and emotionally. If you are one of these people and you have a stressful job/life situation, avoiding too many intense sessions is important. One anaerobic session per week is enough. For the rest of your workouts, train at your heart rate (see my blog post on heart rate training).