## 4 Discussion
The differences may be explained, since patients who suffer from PF have a different step length that affects the normal cadence of the human gait, probably because they suffer from pain when they walk. Additionally, [PERSON] et al. demonstrated that the pronator foot showed an increase in the stride time in seconds, and in gait cycle duration and gait cadence [13]. The literature regarding this idea indicates that 50% of patients with PF have pronated feet [13]. Furthermore, another study showed that in the gait analysis of these patients, the pronation component was up to four times greater than in the healthy control group [13]. The present study provides new evidence of alterations in the gait cycle recorded with the OptoGait optical sensor system in a group of subjects with plantar fasciopathy versus control subjects. These findings may have clinical implications, since differences between the groups may be used to detect a potential dysfunction, an injury, or an alteration in the tissue of plantar fascia, or a mechanical alteration during the gait cycle. Furthermore, the opposite may also be understood, with the gait alteration being responsible for potential PF; in both cases, the clinical approach should include gate re-education. Thus, the presented measurements may be used in injury prevention programs, and as an improvement indicator after a treatment program. Furthermore, the posture adopted during walking presented in subjects with bilateral PF may also be used to propose new active treatment programs, with the aim of using all or some of the parameters, such as modifying step length, contact phase, speed, cadence, and propulsion, among others, to specifically focus and to define the exercise. Future studies should focus on postural evaluation, gait re-education, and proprioceptive treatment programs, to assess and to better understand the relationship between gait behavior and the presence of PF, as well as their clinical importance when assessing PF. Furthermore, in relation to chronic pain, studies that analyze psychological factors, such as kinesiophobia, self-efficacy, or pain catastrophizing, as well as lifestyle and intrinsic factors, would be of interest since the perpetuation of the plantar fascia is multifactorial. This study has several strengths, including the similar demographic characteristics of the different groups, a careful screening for exclusion criteria, which was carried out by an expert in ultrasound imaging, and the proposal of the presented results as a potential measurement to assess potential dysfunction or alteration in the plantar fascia. However, the present study has some limitations that should be recognized. Firstly, the size of the sample is small, and further studies would be necessary to corroborate our findings. Secondly, the cross-sectional design of the study means that the results and the conclusions should be taken with caution. Thirdly, the assessment of the spatio-temporal parameters can be a limitation; therefore, extrapolation to other populations must be interpreted with care. Lastly, age differences between groups were presented, and the control group presented a higher BMI than those with PF.