The neck static stretching protocol consisted of four sets of 45 seconds each, with 45-second rest intervals between sets, resulting in a total intervention time of three minutes. Participants remained seated in an upright position and executed the stretch by gently inclining the head in an anterolateral direction, forward and to the left, while using the contralateral (left) hand to assist the movement. This positioning was intended to specifically target and elongate the right posterolateral neck musculature.

For the neck self-myofascial release intervention, a Theraband® Roller Massager (The Hygenic Corporation, Akron, OH, USA) was utilized. This device features a rigid plastic core encased in high-density foam with a grooved surface, designed to facilitate both superficial and deeper tissue stimulation. The self-myofascial release protocol consisted of four sets, each comprising 45 rhythmic rolling movements performed at a standardized cadence of one roll per second, totaling three minutes of intervention time. The rolling tempo was regulated using a metronome application (Tempo Lite, version 5.0.8; Apple App Store). A 45-second rest interval was provided between sets. While seated, participants self-administered the rolling technique to the right posterolateral region of the neck, ensuring coverage of the largest possible surface area. To optimize tissue elongation, the head was maintained in a gently inclined anterolateral position, forward and to the left, throughout the intervention.

In the control condition (CC), participants remained seated quietly on a chair for a period of 6 minutes, matching the duration of the static stretching and self-myofascial release protocols, but without performing any active intervention, between the baseline and post assessments.

The neck static stretching (SS) protocol consisted of four sets, each lasting 45 seconds, interspersed with 45-second recovery periods (total intervention time: 3 minutes). While seated on a chair, participants performed the stretch by gently inclining the head forward and to the left in an antero-lateral direction and assisting the movement with the contralateral (left) hand to specifically elongate the right posterolateral neck region.

Right hip flexion range of motion (ROM) was assessed using the Active Straight Leg Raise test. Participants lay in a supine position with the test knee fully extended and the ankle dorsiflexed, a setup intended to specifically assess hamstring extensibility. Hip flexion was measured in degrees using the GYKO inertial measurement unit.

Cervical ROM was evaluated with participants seated and secured to the chair at the chest level using inelastic straps to limit trunk movement. The GYKO accelerometer was positioned on the forehead via a head strap and recorded active cervical movements in flexion, extension, right and left rotation, and right and left inclination.

The investigators collected three ROM measurements for each movement (hip flexion, cervical flexion/extension, right and left cervical rotation, right and left cervical inclination) and for each time point (T0 and T1), then used the average of the three measurements for statistical analysis.

Tissue hardness (TH) nwas assessed using a portable TH meter (NEUTONE TDM-N1; TRY-ALL Corp., Chiba, Japan). For cervical TH assessment, the spinous process of C7 served as the anatomical landmark. Measurements were taken at two locations, positioned 2 cm lateral to the right and left of the C7 spinous process. Assessment of TH in the right knee flexors was conducted using the ischial tuberosity as the proximal reference point and the popliteal fossa as the distal landmark. Measurements were obtained at two specific sites located in the proximal third of the posterior thigh: a lateral site corresponding to the biceps femoris and a medial site corresponding to the semitendinosus/semimembranosus muscle complex. All TH measurements were performed with participants in a prone position on a medical examination bed. Participants were instructed to remain relaxed throughout the procedure. For each time point (T0 and T1), three consecutive measurements were taken per anatomical site.