## 4 Discussion
### Position Problem
This is mainly due to the action of the adductor and gracilis (rectus internus) muscles. This behaviour in the internal rotation of the knee, together with its ROM, approximately 5\({}^{\circ}\), is close to that obtained by other authors in their studies [3; 9; 15; 16]. The sagittal plane hip movement (Figure 4) shows a similar behaviour to knee flexion. An extension of this joint is observed from the beginning of the cycle to 150-160\({}^{\circ}\), similarly to that shown by other authors [5; 9; 10]. Moving to the pedal recovery phase, hip flexion occurs again, coinciding with knee flexion. In this plane, the hip shows an ROM close to 40-45\({}^{\circ}\), in line with that shown by other works [3; 9; 10; 15; 16]. The maximum hip flexion value agrees with that shown by [PERSON] et al. [44] and [PERSON] et al. [2] in their work. Due to the existence of bi-articular muscles that act on both joints (hip and knee), the maximum and minimum reached in knee flexion can affect those of the hip, being the determination of the saddle height a fundamental parameter when optimising these values. The frontal plane hip movement shows an ROM around \(8^{\circ}\), close to that reported by [PERSON] et al. [11] and [PERSON] et al. [15]. The negative value indicates a hip abduction, behaviour in accordance with that reported by some authors [5; 9; 10; 15]. The instant of maximum adduction, reached when the crank is close to the top dead centre (TDC), coincides with the instant of maximum hip flexion, registering values close to \(-10^{\circ}\), of the order as shown by other authors [5; 9; 15]. The minimum adduction is reached shortly after passing through the BDC, similar to that shown by [PERSON] et al. [15] in their work. Concerning the hip movement in the transverse plane, it shows an ROM close to \(15^{\circ}\), in line with what is reported in some of the studies [5; 9; 10; 11]. In most of the pedalling cycle, an external rotation of the hip is observed. This movement TE is strongly influenced by the flexion and rotation of the knee. Knee rotation values are maximum near the TDC while hip external rotation values are minimum. When the knee is extended, near the BDC, the rotation capacity of this joint is practically null, as shown in Figure 4. This causes the rotation capacity of the lower body to fall entirely on the hip, which reaches the maximum value of external rotation at this point. A similar behaviour to the one explained above is found in other studies [5; 9]. The dorsiflexion-plantarflexion (DFL-PFL) of the ankle presents an ROM in the order of \(25^{\circ}\), in agreement with that shown by other authors [11; 17]. This movement TE shows both DFL and PFL. These curves' pattern shows that the DFL movement reaches its maximum value at the beginning of the cycle, because the rearfoot movement is the ideal one for the pedal push. Subsequently, the value of this movement decreases until it reaches \(0^{\circ}\) near the instant when the crank is forming \(90^{\circ}\) with the vertical, at which time the effective force applied to the pedals is at its maximum. This behaviour is in accordance with that shown by [PERSON] and [PERSON] [28]. From this instant, the ankle is in PFL, and the value of this movement increases until it reaches its maximum when the pedal is close to the BDC, because it is at this point that the leg is more stretched. From this point onwards, the PFL ankle movement decreases and tends to a DFL movement near the end of the cycle. This is because, as the crank approaches \(345^{\circ}\), the anterior leg muscles at the ankle level and the ilio-psoas, tensor fasciae latae and sartorius at the knee and hip level extend the leg positioning the foot for the beginning of the next power phase [28]. The movements of the ankle outside the sagittal plane are those that show the greatest dispersion of results in the literature as well as in this work.