Plantar fasciitis (PF) is a common condition in the population. One of the interventions used to resolve this condition is myofascial release (MR), which consists of massages that help reduce pain and increase mobility. MR has shown efficacy when applied for 30 minutes, however, it is necessary to compare it with a 15-minute MR intervention, since in clinical practice optimizing time is essential. Accordingly, the present research seeks to evaluate whether there are differences in the application time of myofascial release in people with PF.

Plantar fasciitis (PF) is an acute inflammation of the fascia resulting from degenerative irritation from the median tuberosity of the heel bone to surrounding perifascial structures. Histological findings include granulation tissue, microtears, collagen disorders, and in particular a lack of normal inflammation. It is one of the most common causes of musculoskeletal pain, with a population prevalence in adults aged 50 years or older of 9.6% (95% CI: 8.8 to 10.5) and a population prevalence of disabling pain of 7.9% (95% CI: 7.1 to 8.7), slightly more present in women than in men, with a history of knee, hip, and back pain. It is characterized by pain on the first step and pain during weight-bearing tasks, particularly after periods of rest. Among the possible low-cost and noninvasive treatments that have shown efficacy Manual therapy (MT) is a popular treatment for PF. TM includes treatments such as joint and soft tissue mobilizations, manipulations, myofascial trigger point release, and stretch-contraction-relaxation. In particular, myofascial release is a gradual soft tissue stretching by the clinician that is guided entirely by feedback from the recipient's body to determine the direction, strength, and duration of the stretch to address specific soft tissue restrictions.

TM has been frequently used to treat PF, systematic reviews have reported positive results on pain, function, and pressure pain threshold, but suggest that they should be viewed with caution due to poor methodological quality, intervention heterogeneity in dosing (frequency, intensity, and duration), techniques, and outcome measures, and the frequent use of secondary manual therapy co-interventions. The application of myofascial release is varied in the number of procedures, application time of each technique and total application time of the intervention, without a clear justification regarding the decision of each of these options. A clinical trial applied a protocol for 4 weeks, where each session was performed in 30 minutes, and demonstrated that myofascial release is more effective than the control group, presenting a change in the average pressure pain threshold of 1.3 kg/cm2 at the end of the 4-week treatment. This change is considered clinically important, given that in the literature it has been reported that this difference is > 1.16 kg/cm2. However, the reason for the time used, the number of techniques and the choice of techniques is not justified. In addition, there are no investigations in the literature on the specific effect of myofascial release with a shorter application time in PF. On the other hand, studies with deep massage, a manual therapy technique, combined with flexibility exercise has proven to be effective with an execution time of 10 minutes. Under this context and considering that in clinical practice the optimization of times is essential, it is relevant to carry out a clinical equivalence trial that allows to determine the efficacy of isolated myofascial release in PF, with a 30-minute intervention protocol already carried out and that demonstrated positive effects on the pressure pain threshold, contrasted with a time of less than 15 minutes. Given the context raised, the question arises: In participants with plantar fasciitis, would the application of a myofascial release treatment for 15 minutes have equivalent effects to myofascial release applied for 30 minutes, in the pain and stiffness of the gastrocnemius muscle?

Inclusion Criteria:

• Study participants must be diagnosed with PF
• Age between 18 to 60 years a clinical diagnosis of unilateral PF according to the clinical practice guidelines of the orthopedic section of the American Physical Therapy Association (APTA).
• Pain intensity > 2 on the numerical pain rating scale (NPRS).
• Pain that is most intense upon awakening and decreases during walking. • Duration of pain greater than 3 months and less than 7 months.
• Both sexes.

Exclusion Criteria:

• Who have received ankle or foot interventions within the previous three months, such as physical therapy (manual therapy, exercise, physical agents), injections, long-term history of steroid use.
• History of surgery on the ankle, foot, or inner leg.
• Other causes of heel pain: arthritic (fibromyalgia, gout, rheumatoid arthritis, seronegative spondyloarthropathies), infectious (diabetic ulcers, osteomyelitis, plantar warts), neurological (lumbar radiculopathy (L4-S2), nerve entrapment (branches of posterior tibial nerve), neuroma, tarsal tunnel syndrome, (posterior tibial nerve), trauma (calcaneal stress fracture), tumor (Ewing's sarcoma, neuroma), vascular and pregnancy.

The demographic characteristics and the data regarding the main variable and the secondary variables of the participants will be shared.

Data will be available indefinitely from the moment the results are published.

Data will be available upon request to the principal investigator or the corresponding author of related publications