The therapists will propose the orthotic wedges after examining the foot angles following the foot assessment from the study of Root, the forefoot angle will be determined for both the forefoot and rearfoot wedges. Previous studies recommended the posting at 60% of the measured forefoot angle, up to a maximum of 8 degrees, for extrinsic forefoot varus wedge and the posting at 50% of the measured forefoot angle, up to a maximum of 6 degrees, for extrinsic rearfoot varus wedge. After the posting, all participants will be asked to test the provided foot orthoses within their footwear. If any disturbance has been found during testing, the adjustment will be performed.

The therapists will propose the orthotic wedges after examining the foot angles following the foot assessment from the study of Monaghan et al., the forefoot will be posted at 50% of the measured forefoot angle, and the rearfoot will be posted at 20% of the measured rearfoot angle. After the posting, all participants will be asked to test the provided foot orthoses within their footwear. If any disturbance has been found during testing, the adjustment will be performed.

The 3-quarter-length CFO will be made from thermoplastic material (rigid foot orthoses) which consists of four layers i.e. two layers of 0.5-mm polyvinyl chloride (PVC), one layer of 1.5-mm thick fiber to increase strength of foot orthoses in the bottom layers as well as one layer of 1.2-mm genuine leather in the upper layer to increase comfort. It incorporates a heat-molding process to adjust individual foot shape in prone position. The materials will be set within approximately three minutes.

The orthotic wedges with a full length of 3-mm soft foam layer will be provided to each participant under the molded orthoses; the amount of wedge angle will depend on the rearfoot and forefoot angles of the participants. The present study developed 3-degree, 6-degree, and 8-degree wedges for the rearfoot and forefoot. It was made from solid rubber with a cover of thin fabric. There are three sizes for these products which include small (S), medium (M), and large (L) sizes, according to the foot length of participants.

Pain intensity during the last week will be assessed using the visual analog scale (VAS) which is the high-reliability measurement (ICC = 0.88). The highest pain level is 10 and the lowest pain level is 0. In addition, the foot function will be assessed by the 23-item foot function index (FFI). The present study will use the Thai version of FFI that has been translated forward and backward from the English version. The previous study showed high internal consistency (Cronbach alpha = 0.98) and high test-retest reliability (ICC = 0.86). It is appropriate to use among patients with PHP.

A Trigno Wireless EMG system at 2000 Hz (Delsys Inc., Boston, MA) will be used to collect the EMG data from Tibialis anterior, Peroneus longus, Medial gastrocnemius, Biceps femoris, and Rectus femoris in both legs. The skin will be cleaned with alcohol wipes and the standard EMG electrodes will be positioned following the SENIAM guidelines. Raw EMG data will be exported to Visual3D (C-Motion Inc., Germantown, USA). The dependent variables for the peak and integrated EMG (iEMG) values from such muscles will be found. Then, the data will be normalized to the maximal observed signal during the dynamic contraction during the movement tasks. The participants will be asked to stand with both legs on the firm and foam surface in two conditions i.e. eye closed and eye open, for 20 s in each condition. And then, they will be asked to walk at a self-selected speed to the other end of the 3-m pressure distribution platform.

A self-reported questionnaire will be divided into 4 parts, including individual information (i.e. sex, age, gender, dominant side, body mass index, job, average time during standing and walking), general health information (i.e. characteristics of heel pain, history of injury and fracture at the lower extremity, falling history, types of footwear), foot pain and function, low back pain and lower-extremity pain.