Evaluation of the Prophylactic Effects of the Flavonoid Diosmin on Delayed-onset Muscle Soreness in Humans: a Randomized, Double-blinded and Placebo-controlled Single-center Clinical Trial

Main objective:

• Analyze the potential effects of supplementation with the flavonoid diosmin on DOMS in humans (athletes from the women's five-a-side soccer team from the city of Londrina, Paraná State, Brazil), using the proposed intense dynamic exercise protocol.

Specific objectives:

• Evaluate whether treatment with the flavonoid diosmin reduces muscle pain induced by the intense dynamic exercise protocol;
• Evaluate whether treatment with the flavonoid diosmin reduces systemic (serum) levels of total creatine phosphokinase (CFQ) and oxidative stress (lipid peroxidation and antioxidant capacity) induced by the intense dynamic exercise protocol;
• Evaluate whether treatment with the flavonoid diosmin is capable of improving the reduction in muscular performance and impairment of balance induced by the intense dynamic exercise protocol.

The present project will be carried out through a randomized, double-blinded and placebo-controlled clinical study. A total of approximately 40 female athletes pertaining to the Londrina Esporte Clube (name in Portuguese of the team) women's five-a-side soccer will be recruited for the study. The choice of exclusively women individuals is due to sexual dimorphism in pain perception, thus contributing to the results being more homogeneous and reliable. The criteria for inclusion of volunteer participants in the project will be to be between 16 and 35 years old, and to be able to perform the proposed intense dynamic exercise protocol. Exclusion criteria will include locomotor system dysfunctions or use of analgesic/anti-inflammatory medication at the time of recruitment, as well as being on a calorie-restricted diet or ergogenic supplementation. The study will consist of two experimental groups, made up of healthy individuals, who will perform the proposed intense dynamic exercise protocol, as follows: 1) control group that will receive placebo supplementation (corn starch tablets at a concentration of 750 mg); and 2) intervention group that will receive supplementation with diosmin (tablets at a concentration of 750 mg). Treatment of study participants will occur orally, and everyone will ingest identical opaque capsules containing placebo or diosmin with water. The treatment protocol will be applied before the start (pre-treatment) of the intense dynamic exercise sessions, once a day, during the two days before, and on the day (immediately before) the execution of the exercise protocol. Each experimental group will consist of approximately 20 participants. The project is approved by the Research Ethics Committee (CEP) for Human Beings/Brazil Platform(protocol number 64025122.2.0000.0108). The selected participants will be informed about the objectives and methodology of the study and when there is agreement with the proposed design, the agreement to voluntarily participate in the study will be registered by means of an Informed Consent Form. The intense dynamic exercise modality proposed (concentric and eccentric contractions) for the study will follow the following approach: participants will perform a standardized muscle injury protocol that will consist of a sequence of three sets of repetitions until fatigue of bilateral muscle contractions on a leg-press machine with a 45° angle. Each The participant will have their load previously defined through the 1 repetition maximum (1RM) test, and 70% of the defined weight will be used during the intense dynamic exercise protocol. During each action, the load will be resisted with the legs placed on the leg-press supporter from full knee extension to the 90° knee flexion angle, lasting approximately 3-5 seconds. Between each series, participants will be able to take a 1-minute rest period. The intense dynamic exercise protocol that will be carried out by all participants will be supervised by the project manager and/or collaborators duly trained for such assessments. Participants' clinical signs will be monitored frequently during the activities and in case of discomfort, the activity will be stopped immediately. Analyzes of clinical and blood parameters will be carried out before the start (baseline) and after the end of the proposed intense dynamic exercise protocol (24 and 48 hours) aiming to investigate the possible effects of diosmin on DOMS and related pathological events.