PURPOSE: Extreme conditioning programs (ECPs) are characterized by utilizing a high volume of training and using a variety of high intensity exercises. The purpose of the present study was to monitor the time-course response of cytokines (IL-10 and 1L-1β), immune variables (C-reactive protein -CRP and immunoglobulin A-IgA), hormonal milieu (cortisol-C, total testosterone-TT, free testosterone-FT and testosterone/cortisol-T/C ratios), creatine kinase-CK, muscle performance (jump height) and perceived well-being (WB) following an ECP competition. The initial hypothesis is that an extreme conditioning competition increases inflammatory response as well as metabolic stress, impairing the hormonal milieu, and decreasing muscle performance. METHODS: Nine amateur male athletes (age 27.1 ± 4.1 years; training experience 2.2 ± 1.3 years) completed five workouts over three consecutive days of EC-competition. All variables were measured before, 24 h, 48 h and 72 h following the last day of competition. RESULTS: The EC-competition induced a decrease in IL10/IL1b ratio approximately 5% after 24h, 21% after 48h and 31% after 72h. Delta T/C ratio remained unchanged during the post-competition period. IgA displayed a significant increase 24h and 72h post-EC-competition. The WB status score was higher 72h after the ECP as compared with pre-competition. CONCLUSION: The present findings suggest that ECP induces transient changes in some inflammatory and hormonal biomarkers, and perceived well-being seems to be efficient to detect changes in muscle performance. These data may be useful to coaches for monitoring fatigue and prescribing training (lower intensity sessions and/or resting days) in days following an EC competition. Furthermore, psychometric measurement tools seem to be an effective and easy method for assessing fatigue in participants after the competition.