Background Intensive muscular exercise is known to increase oxidative stress, free radical production and, as part of the physiological process of adaptations to adequate training loads.

Objective To evaluate the antioxidant reserve of blood plasma of elite athletes in the period of high training loads at altitude using a new approach based on kinetic chemiluminometry.

Design Prospective intervention study, without control group.

Setting Professional endurance athletes (speed skating).

Patients (or Participants) 13 elite athletes: 8 males (185 (180–186) cm, 84 (81–86) kg, body mass index 24.6 (24.1–25.3) kg/m², 26(24–27) yrs, VO2max 60 (61–67) mL/min/kg) and 5 females (164 (164–171) cm, 60 (56–61) kg, body mass index 20.8 (20.6–23.2) kg/m², 21(22–32) yrs, VO2max 57 (55–62) mL/min/kg) participated in the study.

Interventions (or Assessment of Risk Factors) Athletes underwent training camp at the altitude 1850 m during 20 days. Blood was taken every four days in the morning on an empty stomach immediately after a day of rest.

Main Outcome Measurements Training impulse and hypoxic impulse were measured to quantify training and hypoxic dose. Measurement of the antioxidant activity of blood plasma by the derivative method of luminol-activated hemiluminescence using 2,2’-azobis (2-amidino-substituted) dihydrochloride (ABAP). The total antioxidant capacity (TAC) andantioxidant capacity by the required proteins were determined.

Results For each athlete a set of antioxidant profiles were obtained. A change in the antioxidant profile for both studied parameters were observed. The indicator that most quickly responds to training load - TAC. In female TAC had a smoother character, which may be associated with lower loads (TRIMP 190(108–242) c.u.in males and 131(117–185)c.u. females) and/or «hypoxic dose» (M 98 (61–104) c.u. and F 52 (50–75) c.u.) or features of the adaptive response.

Conclusions The proposed technique can help in understanding antioxidant reserve of blood plasma and of elite athletes for future management.