INTRODUCTION: The autonomic nervous system (ANS) is responsible for controlling several visceral functions, including the motility and secretion of the gastrointestinal system (GIS). Alterations in the functioning of the ANS can directly influence the physiological mechanisms of the GIS. Due to the importance of the ANS in the control of various body functions, strategies aimed at acting in this system have become extremely important and have been widely used in the literature. Some of the studies involving ANS analysis have shown that osteopathic manipulative treatment is able to promote a reduction in sympathetic ANS activity and an increase in parasympathetic ANS activity in asymptomatic youngsters, however, none of them addressed the GIS, already known to be influenced by autonomic fibers. OBJECTIVE: To evaluate the immediate effects of GIS-directed osteopathic techniques on ANS behavior and pain sensitivity to pressure in young people without symptoms of gastrointestinal disorders. METHODS: The present study is characterized by a randomized, single-blind clinical trial, in which 42 asymptomatic individuals will be recruited, regardless of gender, aged between 18 and 30 years. Volunteers will be randomly distributed into two groups called intervention protocol and placebo protocol. The intervention protocol will be performed by a professional with 10 years of clinical experience in the field of Osteopathy and will perform the techniques of Generalized Discharge of the peritoneum and intestinal wings, Mobilization of the Cecum, technique for the Mesentery Root, Release of the D1-D2 angle, technique for the Sigmoid Colon. The approximate duration of the set of techniques will be 15 minutes with the volunteers positioned supine on a stretcher. The placebo protocol will apply in the same way regarding the positioning and duration of the techniques. The therapist will position the hands in the same regions of the intervention protocol, maintaining superficial contact for 3 minutes in each region, without therapeutic intent. Volunteers will be evaluated for outcomes before and immediately after performing the protocols. The heart rate variability will be measured by capturing the intervals between each beat in ms, using a heart rate monitor and extracting the linear indices in the domain of time, frequency and geometric heart rate variability. The pressure pain threshold will also be measured using a pressure algometer that will be positioned in the vertebral region of T5-L3. Comparisons of variables (indices of HRV and pressure pain threshold) between the intervention protocol group and placebo protocol will be performed using the Student's T test (normal data) or the Mann-Whitney test (non-normal data). All results will be discussed at the 5% significance level.

Inclusion Criteria:

-Health individuals

Exclusion Criteria:

• Participants with neurological impairment and/or pathologies that interfere with autonomic behavior
• smokers
• diagnosis of pulmonary disease
• Participants with theoretical and/or practical knowledge about the techniques that will be applied in the protocol

Will be shared with other researchers when requested

After one year from publication

To request the data, please contact nupi@idot.com.br

Volunteers will be randomly distributed into two groups called intervention protocol and placebo protocol. Only the participant and the outcome assessor will be blinded to the protocols.