Efeitos da suplementação do suco de beterraba sobre estresse oxidativo, desgaste muscular e desempenho de corredores recreacionais

Abstract

Although beet is a food that has been studied from the point of view of the ergogenic effect, there are still some gaps, especially regarding the mechanisms that explain the improvement of performance. Even with the presence of antioxidants, the high nitrate content has been proposed to explain its ergogenic effect. So, the present study aimed to investigate the effects of beet juice supplementation on oxidative stress, muscle wasting and performance of recreational runners. For this purpose, a randomized, controlled clinical trial with cross-over and double-blind design was conducted with 10 recreational runners (42.5 ± 6.4 years, VO2 max 55.2 ± 6.9 mL / kg / min), male. They performed a test until exhaustion on 80% exercise treadmill VO2 max two hours after consuming a dose of 140 mL of beet juice (800 mg NO3-) or control drink. Blood samples were taken before supplementation with beet juice or control drink, two hours after supplementation and immediately after the test until exhaustion for analysis of markers of muscle damage (creatine kinase - CK and lactate dehydrogenase - LDH) and stress (malondialdehyde - MDA and total antioxidant capacity - CAT and nitrite). Performance was assessed through the exhaustion test. Statistical analysis showed that there was significantly increased nitrite with beetroot juice, the time between pre (BET: 12.9 ± 2.4 μM, BET: 20.4 ± 4.4 μM, p = 0.007) and post-exercise. Running time to exhaustion was 22% higher with juice intake (BET: 49.3 ± 18.7, CONT: 40.4 ± 18.2 minutes, p = 0.009). The race promoted increased oxidative stress with the control beverage (3.9 ± 0.7 μM to 4.9 ± 0.7 μM) in the pre-post-exercise moments (p = 0.01), while the juice prevented the increased oxidative stress (3.8 ± 0.9 μM to 3.9 ± 1.0 μM, increase of 2.6%). On the other hand, there was no change in total antioxidant capacity (CAT). The serum concentration of CK increased in both the experimental group (181.5 ± 41.3 U / L to 261.1 ± 77.2 U / L, p = 0.03 and 43.8% increase from pre to post (215.6 ± 126.1 U / L for 316.8 ± 164.6 U / L, p = 0.016 and 46.9%). For LDH, the values remained statistically stable. The present study demonstrated that the acute intake of 140 mL of beet juice promoted a significant increase in nitrite plasma levels, improvement in the performance of recreational corridor, and the attenuation of the oxidative stress induced by the test run to exhaustion.