Twelve‐Week <i>Colostrum Bovinum</i> Supplementation Supports Aerobic Capacity but has No Effect on Body Composition in Endurance‐Trained Males: A Randomized Placebo‐Controlled Crossover Study

Twenty-eight endurance-trained males aged 31.1 ± 10.2 years (body mass [BM] 81.9 ± 9.0 kg) completed this randomized double-blind placebo (PLA)-controlled crossover study investigating the effect of 12-week Colostrum Bovinum (COL) supplementation (25g_COL·day^-1) on aerobic fitness and capacity, time to exhaustion, BM and body composition (BC), and blood lactate concentration. There were four main-before/after supplementation study visits (COL_PRE and COL_POST; PLA_PRE, and PLA_POST). During study visits, BM and BC evaluation, incremental rowing test (IRT) to exhaustion, and evaluation of resting (REST) and post-exercise (POST-IRT) blood lactate concentration were performed. COL, but not PLA supplementation, significantly increased (p < 0.05) time to ventilatory threshold (T_VT). Moreover, the implemented treatments had large (mL·min^-1) and moderate (mL·min^-1·kg^-1) effects on oxygen uptake at VT (VO_2VT), as well as moderate effect on power output at VT (P_VT; W·kg^-1) with the highest values observed at COL_POST visit. Neither significant influence of COL supplementation on time to exhaustion (T_EXH) in IRT, BM, and BC on blood lactate was observed. Importantly, there were significantly (p < 0.05) higher increases in VO_2VT (mL·min^-1 and mL·min^-1·kg^-1) after COL compared to PLA supplementation. In summary, COL supplementation resulted in a favorable increase in T_VT, and tended to improve some of the evaluated threshold indicators, namely VO_2VT and P_VT in endurance-trained male athletes during IRT. Therefore, COL supplementation may be considered as a support to improve aerobic fitness and capacity in endurance-trained males; however, supplementation strategy must be personalized and properly incorporated into the individual training. TRIAL REGISTRATION: The study protocol was registered at ClinicalTrials.gov (NCT06390670).