## 4 Discussion
[11] reported similar spatio-temporal gait parameters as for the use of both bilateral and unilateral PF: step length (41.13 cm and 41.40 cm), load response (18.1 cm and 17.05), pre-swing (18.09 and 17.65 cm), swing (31.92 cm and 33.21 cm), and step time (0.34 s and 0.46 s). These units of measurement are different to those found in this study; they reported using centimeters, whereas we used seconds and/or centimeters for the spatio-temporal parameters. [PERSON] et al. used the Zebris system as a gait study tool, which allowed data on kinetic and kinematic gait parameters to be obtained through a pressure platform on the treadmill. This prioritized the baropodometric pressure data over the kinematic numeral and kinetic data. The difference with our study is that a scientifically validated human gait analysis was used [18] which provides a deeper and more complete understanding of all the spatio-temporal gait parameters (step length, contact phase, swing phase, unipedal support, double support, step time, load response, pre-swing, gait cycle, stride, speed, acceleration, cadence, phase flatfoot, and propulsion) and not just a few of them, as in the Zebris system. Additionally, they did not provide any information on how they diagnosed plantar fasciopathy in their subjects, nor the criteria that they followed to differentiate an injured planar fascia from a healthy one, nor did they correlate the data obtained from the healthy control group and the study subjects. Furthermore, our study had a larger population group. Other studies show that PF negatively affects the static balance parameters measured with the TYMO(r) system, and the gait parameters measured with the G-Walk System [30]. [PERSON] et al. evaluated dynamic stability in runners with PF, runners with resolved PF, and healthy runners, showing that the contact phase values were shorter in the PF subjects when compared to the healthy control groups during the mid-contact phase. However, the contact phase during pre-swing was significantly greater in subjects with PF compared to subjects with resolved PF [31]. These results are in line with this study, and they are supported by [PERSON] et al. [32], who reported changes in the elastic properties of the healthy plantar fascia during the walking contact phase, which showed a rapid elongation of the fascia, with a strain rate of 0.9 +/\(-\) 0.1 s, before and immediately after midstance. In addition, a significantly slower elongation occurred (with a strain rate of 0.2 +/ - 0.1 s) during pre-swing and toe-off. Therefore, the elastic, morphological, and histological affected properties of the plantar fascia, together with the parameters assessed during the human gait cycle, should be further studied. Most of the plantar fascia research is carried out in subjects with unilateral plantar fasciopathy, or in studies that do not specify whether both feet are affected or not [9; 12; 13]. Those subjects that have plantar fasciopathy in only one foot are considered by us to be able to alter the data obtained in any of the aforementioned studies through compensation with the healthy contralateral limb. For this reason, we propose that the pathology being studied should be present bilaterally, as this gives a greater reliability to the results obtained. In spite of this, the results obtained by these studies are in line with ours and show that PF alters the spatio-temporal gait parameters, as expected [10; 29]. [PERSON] et al. [11] reported that subjects with bilateral PF showed a decreased gait step length, unipedal support, and antero-posterior position, along with increased lateral symmetry. For them, the full length of the foot is reduced as the intrinsic muscles are contracted to build the arch. The pronation associated with patients with plantar PF may explain this fact [29]. Pronator patients may have a longer support time in the mid- and forefoot, which generates larger general contact phases, and they may have a greater risk of PF, as found in our study.