Previous research has demonstrated that post-exercise whey protein (WP) intake can attenuate to delayed onset muscle soreness as well as the decline in muscular performance following an eccentric exercise bout. Studies showed that collagen peptide (CP) supplementation along with resistance exercise enhances muscular recovery and function. Yet, the efficacy of CP supplementation in addition to standard nutritional practices in athletes remains unclear. Therefore, the objective of the study was to investigate the impact of combining CP (20g) with whey protein (WP, 25g) supplementation, compared to the same daily supplementary protein dose (45g) of WP on the recovery of muscular performance and short-term muscular adaptation. A secondary aim was to explore the potential of CP supplementation to prevent the development of tendinopathy during resistance training overload. Accordingly, twenty-two healthy male subjects participated in a three-week unilateral eccentric overload training period of the knee extensors while receiving either a dose of WP or WP + CP before and after each training session and on rest days according to a double-blind, randomised, parallel group design. Forty-eight hours after the first training session, maximal voluntary isometric (MVCiso) and dynamic contraction (MVCdyn) of the knee extensors were transiently impaired by ~10% (Ptime < 0.001) in W and WCP while creatine kinase levels were doubled in both groups (Ptime < 0.01). Furthermore, the training intervention improved countermovement jump performance and MVCdyn by respectively 8 and 10% (Ptime < 0.01), and increased serum P1NP concentration by 10% (Ptime < 0.01). However, no differences were found for any of the outcomes between W and WCP. No significant interaction effects were observed for the anteroposterior thickness of the patellar tendon. In conclusion, substituting a portion of WP by CP neither reduced muscle and tendon damage nor did it enhance short-term muscular performance compared to WP intake alone.