## 1 Introduction  
Both recreational and competitive distance running are associated with a plethora of physiological benefits [1]. However, despite the physical improvements caused by running, it is also linked with a very high rate of overuse injuries [2, 3]. Patellofemoral pain (PFP) is a common traumatic knee pathology that typically manifests as retropatellar or peripatellar pain and inflammation, aggravated by activities that frequently load the joint [4]. PFP hasan incidence rate as high as 21% in runners [5], with a much larger prevalence in females [6]. The long-term prognosis is poor, with 71-91% of patients experiencing symptoms 20 years after diagnosis [7]. PFP symptoms may later present with radiographic evidence of osteoarthritis at this joint [8], and pain symptoms force many to reduce or even end their running training [9], causing many to develop associated psychological disorders [10]. The lack of treatment efficacy is attributed to the multifactorial nature and complex aetiology of PFP, which makes the identification of modifiable risk factors problematic [11]. Given the high incidence of PFP in runners [5], an enhanced comprehension of the parameters linked to PFP's aetiology and its distinct incidence in differing populations is essential in order to prevent symptoms and improve management. Recent prospective pooled systematic reviews and meta-analyses have shown physiological indices of quadriceps weakness and hip abduction strength to be risk factors for PFP in military and adolescent populations, although no identifiable risk factors were evident in runners [12]. There is a lack of prospective investigations exploring the biomechanical mechanisms linked to the aetiology of PFP in runners [4]. [PERSON] et al. [13] showed that female runners were at an increased risk of developing PFP in the presence of a statistically greater maximum hip adduction angle. Furthermore, in relation to asymptomatic controls, [PERSON] et al. [14] showed that PFP runners exhibited increased peak hip adduction, hip transverse plane range of motion (ROM), peak knee flexion, peak knee abduction, and peak dorsiflexion. [PERSON] et al. [15; 16] revealed that in female PFP runners, increased hip adduction, hip internal rotation, and tibial internal rotation were evident compared to controls. [PERSON] et al. [17] showed that runners with PFP exhibited higher hip adduction at toe-off, lower hip adduction ROM during late-stance, and longer soleus activation. Conversely, [PERSON] et al. [18] showed that runners with PFP demonstrated reduced peak knee flexion, peak hip adduction, evasion ROM, peak knee flexion velocity, peak hip adduction velocity, and peak hip internal rotation velocity compared with controls. Finally, [PERSON] and [PERSON] [19] revealed that females with PFP demonstrated greater hip adduction and contralateral pelvic drop compared to asymptomatic runners. [PERSON] et al. [12] proposed that these kinematic variations contribute to the development and persistence of PFP by way of increased patellofemoral joint stress, although patellofemoral joint loading has not yet been explored in runners with PFP in relation to asymptomatic controls. Although previous analyses have explored the biomechanics of running in those with PFP compared to healthy controls, the majority utilized only female runners or a mixed-sex sample, without considering of the effects of sex. As such, the effects of sex on the biomechanics of running in those with PFP are poorly understood [12]. [PERSON] et al. [20] compared the biomechanics of running in male and female runners with PFP, and showed that females exhibited greater peak hip adduction compared to both males with PFP and male controls, whereas males with PFP ran with a greater peak knee adduction compared to symptomatic females and male controls. A drawback of this investigation was the lack of a female control group, and [PERSON] et al. [4] undertook the only investigation examining male and female runners with PFP in relation to asymptomatic controls of both sexes.