Knee strength difference between lower limbs and jump performance in athletes with patellar tendinopathy and healthy controls

BACKGROUND: The aim of this case-control study was to compare knee strength and jump performance both in athletes with patellar tendinopathy (pT) compared to healthy controls. METHODS: Eighty recreational athletes divided into 2 groups, patellar tendinopathy group (pTG; N.=40) and asymptomatic control group (CG; N.=40) matched by age, height, weight and sport participated in this study. RESULTS: Six-Repetition Maximum (6RM) Test were conducted to estimate maximal isotonic muscular strength using leg extension and leg press machines, while vertical countermovement jump (CMJ) and triple hop for distance were performed to assess jumps capacity. An adjusted analysis revealed that the difference between the pT group and the asymptomatic group in CMJ was 11.024 cm (p value <0.001) and 0.18 m in triple hop (p value <0.001). Furthermore, the difference between both lower limbs in the pT group was 9.02 kg (p value <0.001) and 3.76 kg (p value = 0.02) in leg extension and leg press evaluations, respectively, compared to the control group, regardless of age, height, weight, and sports activity. CONCLUSIONS: Athletes with unilateral pT had impaired strength and single leg jumping performance compared with matched healthy controls, yet they have greater double leg jumping performance. There was less evidence for side-to-side impairment suggesting bilateral impairment.