INTRODUCTION
CrossFit® (CrossFit®, Inc., Washington, DC, USA) is a relatively new but extremely popular non-Olympic sport with mixed workouts that encompass many types of functional movement patterns in a single session, performed at a medium- to high-intensity level1. Since its creation in the 1990s, it has become a competitive sport with about 11,000 gym affiliates and over 200,000 athletes worldwide in 20142.
Physical exercises during training sessions and competitions are constantly varied. Three sports are the basis of CrossFit® exercises: gymnastics (G), metabolic conditioning (M), and weight lifting (W)3. The literature states that CrossFit® training elicits a high acute cardiovascular response as well as large increases in aerobic and anaerobic performance4.
CrossFit® is a competitive sport with varied stressors and external and internal pressures not controlled by athletes, which can physically and mentally destabilize athletes before and during a competition. External pressures include, among other factors, athletes’ performance evaluation by their coach and other participants, coaches’ expectations about athletes’ performance, and cheering behavior. Internal pressures include the achievement of personal goals, expectations of success or failure, and athletes’ own perceptions of wins and losses5.
Considering hormonal responses, cortisol is the main glucocorticoid released by the adrenal cortex in a stressful situation. It is considered the stress hormone, since its production and secretion increase during and after exposure to some stressors6. In this context, the presence of cortisol in competitive situations is an indicator of stress. Cortisol levels can be assessed by blood plasma, urine or saliva samples. Salivary cortisol, specifically, is an important, effective, affordable, fast, and non-invasive measurement variable. Salivary cortisol can be collected in any competitive and extracompetitive situation without causing reactivity, or practical or ethical embarrassments6.
As mentioned above, physical exercises affect cortisol levels. The hormonal response to exercises depends on several factors, such as exercise intensity, duration, mode and level of training. It is important to assess cortisol levels during high-performance competition in professional athletes because the increase in physiological cortisol levels may result in a decrease in testosterone levels, loss of strength and impaired muscle recovery. High cortisol levels increase loss of muscle mass (cortisol catabolic effects) and contribute to the occurrence of overtraining, as it causes chronic fatigue, loss of appetite, decreased performance, infections, sleep disorders, mood swings, and disinterest in training.
Therefore, this study aims to analyze the effects of three consecutive CrossFit® training sessions on salivary cortisol. The initial hypothesis is that three consecutive CrossFit® training sessions increase cortisol responses, harming physiological stress.