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.