Effect of Dry Needling Plus Vibration on Myofascial Trigger Points in Individuals With Nonspecific Low Back Pain

This variable refers to the participants' low back pain at the time of the assessment. It does not include the pain caused by the treatment itself. The Numeric Pain Rating Scale (NPRS) will be used. This scale ranges from 0 to 10, where "0" indicates no pain and "10" represents the worst possible pain intensity. Patients will select the number that best reflects the intensity of their pain. The NPRS is a widely used, simple scale that offers good sensitivity and provides suitable data for statistical analysis.

The NPRS will be used again, but in this case, to assess the pain generated by the treatment itself on the patient. The focus will not be on the non-specific low back pain (NSLBP).

It is a highly prevalent adverse effect of dry needling. This pain does not refer to that caused by the MTrPs, but rather to that caused by the needling itself.

This variable will be measured using the NPRS once again.

It will be evaluated using a specific qualitative scale developed explicitly for this project. It is a scale which adopts a holistic approach, prioritizing two key variables, "pain during the treatment" and "post-needling pain," as the primary determinants of the overall score. However, other factors, such as emotional experience, physical state, satisfaction level, and environmental influence, will also be considered.

Functional disability will be assessed using the Roland-Morris Disability Questionnaire (RMDQ), a tool designed to measure physical disability caused by low back pain. The questionnaire consists of 24 items, with scores ranging from 0 (no limitations) to 24 (maximum possible disability), evaluating limitations in various daily life activities.

This variable will be measured using the "microFET-2 dynamometer". Muscles assessed will include the lumbar erector spinae, multifidus muscles, and hip abductor musculature. Participants' weight will be recorded to normalize the collected data. Three maximal isometric contractions will be performed, each lasting 5 seconds, with a 1-minute rest period between them. The average of these measurements will be used for statistical analysis.

It will be recorded using mDurance equipment. For each measurement, the amplitude of the electromyographic activity (measured in microvolts -mV-) of the target musculature at rest will first be recorded for 10 seconds. Then, the muscle activation level during maximal isometric contraction will be recorded to normalize the electromyographic signal. This will follow the same methodology as the maximal isometric strength variable (three maximal isometric contractions of 5 seconds each, with 30 seconds of rest). In this case, the parameter of interest will be the signal's peak amplitude. Lastly, 10 dynamic repetitions of the functional movement "front squat" will be evaluated. This data will determine the percentage of muscle activation relative to maximal isometric contractions, known as the "percentage of maximal voluntary isometric contraction" (%MVIC).

PPT will be assessed using a digital algometer (Somedic SenseLab, Suecia) with a 1 cm² rubber tip. The pressure will be applied perpendicularly to the skin at a constant rate of 0.5 kg/s until the participant reports that the pressure sensation changes to pain. To differentiate between peripheral and central mechanisms, measurements will be taken at two locations: 1) Locally, directly over the treated MTrP in the lumbar region (peripheral sensitization), and 2) Distally, at a remote site such as the tibialis anterior muscle (central sensitization). Before the actual tests, the PPT will be familiarized by applying it to the participant's dominant arm until the participant becomes familiar with the test procedure. Three measurements will be taken at each site, but not at precisely the same point to avoid influencing the pain threshold from previous measurements, with a 30-second rest interval, and the mean value will be used for statistical analysis.

The Short Form-36 Questionnaire will be used to assess this variable. This survey comprises 36 questions about general health. The questionnaire consists of eight subscales (physical functioning, physical role, bodily pain, general health, vitality, social functioning, emotional role, and mental health), summarized into two scores: physical and psychological health. Scores range from 0 to 100% and reflect self-perceived health-related quality of life.

When both interventions (dry needling or dry needling + vibration) are applied, it will be noted whether local twitch response has occurred or not. Although this response is not necessary to consider the dry needling treatment applied correctly, and whether or not a local twitch response occurs is not a fundamental aspect of this study, it is deemed appropriate to record this variable for descriptive purposes of the sample and for potential discussion in the findings.

We hypothesize that DN+V, being less aggressive than DN, will reduce the risk of adverse effects associated with DN (hematomas, bleeding, pain, dizziness, etc.) Adverse effects will not be included in the statistical analysis; however, these data will provide valuable descriptive information, given that adverse events are often underreported in research despite their clinical relevance.