Abstract
The aim of the present study was to investigate the effects of distinct resistance training frequencies with equated-volume conditions in morphological and functional adaptations of the patellar tendon. Twenty-seven recreationally resistance-trained subjects (men [n=17] and women [n=10]) (age: 20.8 ± 1.9 years [range 18 to 25 years]; height: 1.73 ± 9.8 cm; total body mass = 73.2 ± 11.7 kg; previous RT experience = 3.3 ± 1.6 years) volunteered to participate in this study. A total of 16 training sessions were performed during the study period. Each subject's leg was randomly allocated to one of the following training protocols: 2 training sessions/week (2x) or 4 training sessions/week (4x). Measurements of tendon cross sectional area (CSA) and length were performed through ultrasound imaging. One repetition maximum test was performed to assess patellar tendon force (PTF) unilaterally. For CSA (2x: Δ= -1.3%; 4x: Δ= -0.9%), and length (2x: Δ= -0.4%; 4x: Δ= 1.2%), no significant differences were observed within or between conditions (all p > 0.05). For PTF, a significant difference was observed between conditions (mean difference = 0.05 [-125 to 224] p= 0.001). In conclusion, the leg extension exercise performed 2 vs 4x/week induces similar patellar tendon morphological responses. However, the increase in force seems to be enhanced by a lower weekly training frequency associated with a longer intervention period.