## 4 Discussion
[8] observed very similar total forces applied at the metatarsal region during maximum isometric ankle plantarflexion (210 \(\pm\) 39 N) and dorsiflexion (190 \(\pm\) 39 N) with the knee in fully extended posture, albeit measured with a manual dynamometer. Regardless of the knee posture or ankle flexion direction, the dominant leg consistently displayed significantly greater ankle strength compared to the non-dominant leg. This was consistent with that reported by [PERSON] et al. [9] in a population of adult males (maximum difference of 13.6 Nm between dominant and non-dominant leg) and by [PERSON] et al. [15], who observed 14% greater strength in the ankle of the dominant leg at 30 deg plantarflexion. The ankle dorsiflexion forces measured here were compatible with the maximum voluntary ankle moments reported in the literature with the ankle in neutral position [16], and the plantarflexion forces were the highest in the fully extended knee posture. Unlike what has been reported by other studies [7], the forces in dorsiflexion were generally larger than those in plantarflexion in most conditions. However, with the extended knee, in only 55% of the recorded samples, dorsiflexion was larger than plantarflexion. Indeed, plantarflexion moments in healthy populations are usually reported to be about 3 \(\div\) 4 times larger than dorsiflexion moments [7]. The lower plantarflexion forces estimated here are likely due to the supine position of the subjects and the immobilization of the thigh at the knee joint, which reduces the possible involvement of the more proximal lower limb muscles and joints. In addition, with respect to the fully extended knee posture, a flexed knee results in a greater mechanical advantage for the calf muscles and in a more stable leg, which can thus produce larger ankle forces (see Figure A1). While most of the current literature has focused on the assessment of maximum forces and moments at the ankle in different isokinetic and isometric conditions, the present study--similar to that reported by [PERSON] et al. [8]--aimed to measure ankle forces by replicating the same conditions used by clinicians during manual assessments. For this reason, these experimental conditions cannot be considered suitable to measure the actual maximum ankle forces in plantarflexion. When used to assess the ankle strength deficit in a patient affected by foot-drop, the AFT allowed for objectively quantifying a reduction in ankle force in the affected limb of about 90% with respect to that in the non-affected limb. These measurements were still rather consistent across trials (CV = 17%), also considering the severe pathological condition of the exemplary patient assessed here. The AFT helps to provide an objective quantification of the neuromuscular deficit, which overcomes the subjective evaluation performed by clinicians. The measured ankle strength could also be useful to establish the right rehabilitation protocol and in the design of custom orthotic devices tailored to the patient's needs in addition to the patient's anatomy [17; 18; 19]. This study has some limitations. The proposed procedure aims to measure ankle forces by replicating the same conditions used by clinicians during manual assessments. However, the present approach does not allow for the maximum absolute force to be measured, especially in plantar flexion (see Figure A1 in Appendix A). In addition, the pilot study was carried out on one exemplary patient only. It should be highlighted that the AFT apparatus is still a prototype, it can measure ankle forces only in the sagittal plane, and proper validation should be conducted in a larger cohort of patients with different deficits of the ankle muscles before it can be used in clinical practice. This would also allow us to investigate possible correlations between clinical scores and instrumental measurements.