## 4 Discussion
### Spatiotemporal Parameters and Gait Phase Analysis
In this context, several investigators have demonstrated significant differences in the peak and overall range of motion across the lower limb joints, including the forefoot, midfoot, and rearfoot joints, as well as the knee, hip, and pelvis between individuals with overpronated and neutral foot type [15; 17; 33; 51; 52]. However, the kinematic changes between groups were generally small and challenging to compare. It is possible that biomechanical deviations are not substantial enough to disrupt spatiotemporal parameters since hyperpronation primarily affects foot mechanics rather than the overall gait cycle, allowing spatial and temporal elements of gait to stay within normal ranges. Additionally, muscles that support the arch, such as the abductor hallucis [16; 29], along with the flexor digitorum brevis and longus [17; 53], have demonstrated hypertrophic changes in individuals with foot hyperpronation. These individuals also show increased EMG activity in the long (e.g., tibialis posterior, tibialis anterior, flexor hallucis longus), and short muscles of the foot (e.g., abductor hallucis, flexor digitorum brevis) involved in gait [54; 55; 56]. Such adaptations may ultimately enhance foot stability, facilitate efficient propulsion, and prevent changes in spatiotemporal gait parameters. This effect is particularly noticeable during uphill walking, where a collapsed medial foot arch in individuals with hyperpronated feet is expected to impact propulsive ability and related spatiotemporal parameters. Because uphill walking requires increased effort to propel forward while countering both higher frictional resistance during toe-off and stronger gravitational forces, compensatory muscle activation plays a key role. Increased activation of the tibialis anterior during the contact phase and the tibialis posterior during midstance and propulsion may enable individuals with foot hyperpronation to offset reduced plantar flexor moments [33], reinforce medial longitudinal arch stability, and ultimately achieve effective propulsion with gait characteristics similar to those of a neutral foot type. The same adaptive neuromuscular mechanism may also apply during downhill walking, where participants decelerated to counteract gravity-assisted propulsion and manage the increased friction demands of heel strike. Both foot type groups also demonstrated increased outward foot rotation during uphill walking and increased step width during downhill walking compared to level walking. Individuals with hyperpronated feet showed greater, albeit non-significant, outward foot rotation compared to those with neutral feet, likely compensating for the restricted ankle dorsiflexion observed in the present study. This response may be further influenced by the increased activation of the peroneus longus and biceps femoris during uphill walking, which facilitate foot eversion, abduction, and external rotation of the tibia, helping to prevent tripping and improve foot contact for effective propulsion [57; 58]. The increased step width during downhill walking was likely a response to heightened lateral instability induced by the ankle joint's open-packed position in plantar flexion during heel strike, combined with eccentric muscle contractions and proprioceptive disturbances that occur during downhill walking [59; 60; 61].