Differents Intensities of Passive Stretching on ROM, Neuromuscular and Performance in Soccer Players: A Blinded RCT

Intensity is a "qualitative" variable of a muscle stretching protocol, which is very little studied due to its inherent characteristic of the individual being stretched. However, it was pointed out as an important factor for ADM gain. To verify the effects of different intensities of static passive stretching on flexibility, neuromuscular and functional performance in soccer athletes.

It is a randomized, controlled, clinical trial, composed of male subjects, soccer players, randomly divided into 4 groups: Control Group (CG), Experimental Group 1 (GE1), Experimental Group 2 (GE2) And Experimental Group 3 (GE3). Initially, the measurements of flexibility (passive and active), neuromuscular (muscular passive torque, electromyographic activity), and functional (vertical jump and shuttle run test) of non-dominant lower limbs, performed before and immediately after the 1st And 48 hours after the last session. The GC will only be submitted for initial evaluation and final re-evaluation. The experimental groups will undergo a protocol of static passive stretching containing 10 sessions, divided into 3 weekly sessions, with 3 maneuvers of 30 s, but with different intensities (Tolerable Maximum Pain, Maximum No Pain Discomfort, and Stretching Sensation Without Discomfort) Established from a PERFLEX-modified visual scale. Groups with higher static passive stretching intensities (Maximum Tolerable Pain and Maximum Painless Discomfort) are expected to have greater gains in flexibility, with no change in muscle passive torque, electromyographic activity and functional performance, while the intensity of Feeling of Stretching without Discomfort (in a comfort zone) provides a greater decrease of the muscular passive torque, without significant change of the flexibility, in individual athletes of soccer. This work may contribute to the clinical practice of health professionals, since it seeks to improve the elaboration of the clinical prescription of protocols of static passive stretching (whether performed by the individual or not), establishing optimal levels of intensity for a given muscle group.

Eligibility Criteria:
Inclusion Criteria:

* (1) being male; (2) age range between 18 and 35 years of age; (3) Body Mass Index (BMI) between 19 and 27; (4) be a soccer player with 4 to 5x weekly training; (5) not participating in lower limb stretching programs; (6) no history of injury, trauma, previous surgeries and lower limb disease in the last 6 months; (7) absence of musculoskeletal, cardiorespiratory and neurological disorders that prevent the accomplishment of evaluation and treatment protocols; (8) not under the action of drugs that cause muscle relaxation or that may inhibit tonic muscle action (9) present a limitation of WMD (muscular shortening degree) with ischiatibial extensibility of less than 165 degrees of active extension of the knee with the hip Flexed at 90 °.

Exclusion Criteria:

* (1) initiate stretching practice involving LLLs in daily activities outside the collection site during the study period; (2) not performing any of the evaluation and / or intervention procedures; (3) discontinuance in participating in the research.