We investigated whether 10 weeks of pre-season soccer training (including high-intensity resistance exercise) with hydrolysed collagen (COL) supplementation would confer greater changes in patellar tendon (PT) mechanical and material properties compared with placebo (PLA) in professional female soccer athletes. Eleven athletes from the first team squad of a Football Association Women's Championship soccer club volunteered to participate in this study (age, 25.7 ± 4.2 years; height, 1.68 ± 0.04 m; mass, 64.0 ± 4.6 kg). Participants were pair-matched for baseline knee extensor maximum isometric voluntary contraction torque, age, height and mass and were randomly assigned to the COL group (n = 6) or PLA group (n = 5). Participants were given 30 g COL or energy-matched (36.5 g maltodextrin and 8.4 g fructose) PLA, plus 500 mg vitamin C before each training session, which consisted of high-intensity lower-limb resistance exercise, plyometric or pitch-based exercise 3 days/week for 10 weeks during the pre-season period. We assessed knee extensor maximum isometric voluntary contraction torque and PT properties using isokinetic dynamometry and ultrasonography before and after the intervention. The PT stiffness [COL, +15.4% ± 3.1% (d = 0.81) vs. PLA, +4.6% ± 3.0% (d = 0.32), P = 0.002] and Young's modulus [COL, +14.2% ± 4.0% (d = 0.65) vs. PLA, +3.4% ± 2.8% (d = 0.15), P = 0.004] increased more in COL than in PLA. There was a main effect of training on PT cross-sectional area (P = 0.027), but no interaction effect (P = 0.934). To conclude, 10 weeks of pre-season soccer training (incorporating high-intensity resistance exercise) with 30 g COL increased PT stiffness and Young's modulus more than training alone in professional female soccer athletes. This has positive implications for improving athletic performance and mitigating injury risk. Highlights What is the central question of this study? Does 10 weeks of soccer training (incorporating high-intensity resistance exercise), supplemented with 30 g hydrolysed collagen ingestion, change the mechanical and material properties of the patellar tendon more than training alone in professional female soccer athletes? What is the main finding and its importance? Changes in patellar tendon stiffness and Young's modulus were greater following 10 weeks of training with 30 g collagen supplementation compared with training alone. Given that a stiffer tendon can tolerate greater stress and transmit force more efficiently, combining collagen ingestion with resistance training might help to mitigate injury risk and improve physical performance in this under-researched population.
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