Effects of Foam Rolling, Foam Rolling with Dynamic Movement, and Static Stretching on Plantar Flexor Range of Motion and Tissue Properties in Healthy Participants

Primary outcomes

1. Plantar Flexors ROM

   Time frame: 5 minutes

   Each participant was placed prone on a medical bed with both feet hanging out of the bed. Inelastic straps were used to fix the pelvis and the contralateral leg of the tested participant. A flat rigid surface was fixed on the sole of the foot. A two arm electronic goniometer (Digital Angle Ruler, resolution0.05°, accuracy±0.2°, repeatability0.05°) was then placed with one arm parallel to the flat surface positioned on the foot sole and the other arm following the diaphysis of the fibula. Starting position was set with the foot and the leg forming a 90°angle. The investigator passively pushed the foot into a dorsiflexion motion to the limit of available ROM, or the maximum tolerable pain for each participant.

2. Pain Pressure Thresholds

   Time frame: 5 minutes

   PPT was assessed through a portable algometer(FPX25 Pain Tester, Wagner Instruments,CT,USA). The participant's measurement position and posture were similar to TH. The algometer was positioned perpendicular to the direction of the muscle fibers. The investigator pushed the metal rod of the algometer at a pressure of 1kg per second over the muscle belly of the participant. The participant was instructed to say "stop" when pain, rather than just pressure, was experienced.

3. Localised Bioimpedance Analysis (L-BIA)

   Time frame: 5 minutes

   L-BIA was performed using a single frequency phase-sensitive device(BIA-101 Anniversary Sport Edition, Akern Systems, Firenze-Italy) at 50kHz and 400μA to measure PhA and vector length. Two pairs of electrodes (source(I) and detector(V) electrodes) were used. One pair was positioned on the upper part of the leg, with the lateral part of the I positioned on the popliteal crease(Lee et al., 2023) and the V, positioned caudally, parallel to I, 5cm apart. The other pair was positioned on the lower part of the leg with the lateral part of the I positioned above the tibial malleolus and the V, in a cranial direction parallel to I, 5cm apart. Prior to each test, the BIA measurements of the analyzer were validated using a precision circuit with acceptance for resistance(R) measurements of 383ohm(Ω) and reactance(Xc) values of 45Ω.

4. Drop Jump Height (DJ)

   Time frame: 5 minutes

   A unilateral DJ was assessed through an Optojump™ system(Microgate, Bolzano, Italy) connected to a personal computer with dedicated software(OptojumpTM Next software). The system consists of two optical bars, a receiver and a transmitter, positioned 1m apart. The bars identify ground contact time(with a precision of 1ms) and then convert non-contact time into cm. Based on recommendations on optimal jump height(20 to 60cm), all jumps were performed from a box with a height of 40cm. Participants had to stand upright on the box with their hands positioned on their hips. At the "go" of the investigator, the participants had to jump forward from the box into the opto-jump system avoiding stepping down from the box or hopping off of the box. Once the participant reached the ground with their dominant limb, without flexing the knee, had to jump as high as possible. A 30s rest was given between each trial.