Background: There is consensus about the important influence of psychological aspects on athlete`s physical performance. Therefore, stress has been studied under the perspective that
its management may be used to improve performance, both in physical and psychological aspects. Peripheral mechanisms of the stress response include the activation of the hypothalamic-pituitary-adrenal
axis (HPA) and the sympathetic nervous system (SNS). The HPA axis activity can be estimated by the salivary cortisol concentration (SCC). The SNS activity can be assessed through the heart rate
variability (HRV), which is the result of the balanced actions of both divisions of the autonomic nervous system (ANS), the sympathetic and the parasympathetic systems. Biofeedback technique has been
used as a potential training for stress management in sport. However, its effectiveness has not been evaluated yet. Objective: The aim of this study was to evaluate the effect of
biofeedback on HRV and SCC in athletes.
Methods:Volunteers, professional athletes practicing futsal or volleyball were randomly distributed into two groups (control and intervention). Individuals in the intervention group
attended 15 sessions of biofeedback, 30 minutes each, three times/week. SCC and the perceived stress index (PSI), quality of life (QOL SF-36), trait and state anxiety (IDATE) as well as performance
were determined before and after the intervention period. HRV was evaluated after the intervention.
Results: The athletes submitted to the biofeedback training program (n = 11) showed a reduction in anxiety state (48.0 ± 1.2 vs. 41.0 ± 1.8) without altering anxiety trace (46.0 ±
1.6), PSI (0.29 ± 0.04 vs. 0.33 ± 1.9), QOL domains, or any of the HRV indexes (RR mean interval, SDNN, RMSSD, pNN50, LF, HF, DS1, SD2, ⍺1 or ⍺2). CAR and the area under the curve of cortisol were
also reduced. Performance, indicated by the score get by the athlete and the number of mistakes he made, was improved since after the feedback training they were able to get more points and presented
lower number of mistakes.
Conclusions: biofeedback training reduced anxiety and SCC in volleyball and futsal athletes in the day of competition, probably contributing to improve athletic performance, without
altering the ANS activity as measured trough the HRV. Financial support: CAPES.