David Ferguson, Ph.D, RCEP
In the competitive sport world, athletes are required to train year-round in order to maintain a state of physical conditioning that will optimize performance during game day. With certain sports having longer seasons than others, this idea of year-round training can lead to the athlete becoming “overtrained”. Overtraining is described as a decrease in lean muscle mass, an increase in body fat, an increased state of fatigue, a decreased performance capacity and an increased incidence of injury. Because overtraining can lead to injury to the athlete, researchers are interested in identifying whether an athlete is approaching a state of overtraining before the physical affects described above appear.
Researchers have shown that cortisol levels in athletes rise several days before the athlete shows observable signs of overtraining. The hormone cortisol is produced as a result of stress, whether by emotional, psychological or physical factors. During periods of stress, cortisol acts on muscle cells, fat cells, and various other tissues, causing an increase in protein breakdown, a decrease in protein synthesis, an increase in the inflammatory response, a decrease in insulin production, and a decrease in the body’s immune response. Under conditions of periodic stress, the cortisol response facilitates survival and health maintenance by giving the body access to glucose for fuel; however, in a year-round athlete this stress response can cause a decrease in performance and possible injury.
While there are several ways to measure cortisol, the current noninvasive method to evaluate the amount of cortisol in an athlete is to take a sample of saliva. Upon arising, the athlete spits into a tube. That tube is then sent to a lab where the amount of cortisol is measured. Over time, the lab can chart the increase or decrease in the athlete’s waking cortisol level. This is important because an increasing daily cortisol level signals that the athlete is under stress, typically as a result of intense physical stress/fatigue. Knowing that this physical stress/fatigue can lead to overtraining and injuries, the athlete’s coach can then alter the training program, allowing the athlete to recover.
Changing an athlete’s training program can involve decreasing the number of practice times, the practice length or the amount of weight being lifted in the gym. If this stress includes mental fatigue (i.e., stress over an upcoming game), a sport psychologist may be employed to help the athlete manage stress.
By monitoring changes in cortisol fluctuations, coaches can modify the training program to prevent a state of overtraining; thus something as simple as spitting in a tube can prevent injuries and ensure optimal performance on game day for the year-round athlete.
For further readings related to this topic:
- Filaire E, Bernain X, Sagnol M, and Lac G. Preliminary results on mood state, salivary testosterone: cortisol ratio and team performance in a professional soccer team. European Journal of Applied Physiology 86: 179-184, 2001.
- Minetto MA, Lanfranco F, Tibaudi A, Baldi M, Termine A, and Ghigo E. Changes in awakening cortisol response and midnight salivary cortisol are sensitive markers of strenuous training-induced fatigue. Journal of Endocrinological Investigation 31: 16-24, 2008.