This study investigates the influence of two different stretching techniques on the flexibility of the muscles that are in the posterior thigh, after a training period.

The study will last for six weeks where the volunteers need to go to the lab twice for evaluation, and for four weeks, three times a week for the application of stretching training.

Evaluation before and after the training period consists of applying hip and knee flexibility tests, evaluation of strength, muscle activation and muscle architecture. The Flexibility tests are: (1) Straight Leg Raise Flexibility Test (SLR), where the volunteer will be positioned supine on a stretcher. Then the appraiser will perform hip flexion keeping the knee extended and relaxed foot to the angle at which the person refer discomfort while the contralateral limb remain firmly leaning on the table; (2) Modified Passive knee extension (TEJ), where the volunteer will be positioned supine on a stretcher. The assessor shall determine the hip member to be rated at 90º and perform knee extension to the angle at which the person refer discomfort. The contralateral limb remain firmly leaning on the table.

For the evaluation of muscle strength the volunteer had sat on equipment, makes five repetitions of bending and straightening the knee to familiarize yourself with the equipment and after will make other five replicates doing maximum strength.

To evaluate the electrical activity will be the depilation of the skin with a razor and cleaning with an alcohol swab after adhesive electrodes will be placed for collection of muscle activity, the electrodes do not emit shocks.

The muscle architecture will be assessed via a ultrasound , to its use the use of a water soluble gel to improve the machine's skin contact is required.

For the intervention, the stretching will be held in both legs, where the volunteer will remain lying on a stretcher with fixed trunk with velcro straps and the researcher will carry out the elongation raising the leg drawn to the moment of discomfort the volunteer will refer and will remain for 30 seconds (s) in case he belongs to passive static stretching group, if the stretching group of proprioceptive neuromuscular facilitation, will be in the same position, but before the 30s of stretching, he you will have to push against during 6s to lower leg against the researcher.

If he belongs to the control group, have only two trips to the laboratory for testing, will make an initial assessment and after four weeks will return to perform the tests again, in the period between assessments will not need to go to the lab because it does not make intervention elongation.

It is possible that there discomfort during flexibility testing, strength testing and stretching training. After the tests can still experience muscle pain should disappear within 48 hours. The risks of research are minimal, not exceeding those of a strength training session and stretching.

Inclusion Criteria:

• Female;
• Aged between 20 and 30 years;
• Be sedentary as classification of the International Physical Activity Questionnaire (IPAQ);
• Make Use of oral contraceptives;
• Body Mass Index range 18 to 24.

Exclusion Criteria:

• Provided history of musculoskeletal injury or surgery of the lower limbs;
• Provide continuous pain in the legs or lower back pain;
• Make use of painkillers, anti-inflammatory and / or muscle relaxant;
• Being in pregnancy;
• Present laxity ligament;
• Achieve zero degrees of extension in Knee Extension Test Modified.