Background – A novel hydrolysate (NatraBoost XR, NBXR) of whey protein isolate (WPI) reduced production of tumor necrosis factor-α (TNFα) and increased cell growth in vitro.
Objectives – This study examined whether feeding NBXR could enhance recovery of muscle function following eccentric exercise.
Design – Muscle soreness (MS, by visual analogue scale), serum creatine kinase activity (CK), plasma TNFα and insulin concentrations, and knee extensor peak isometric torque (PIT) were determined in 40 healthy sedentary males at baseline. 100 maximal eccentric contractions (ECC) of the knee extensors were then performed. MS, CK TNFα, insulin and PIT were then reassessed prior to consuming 250 ml of flavoured water (FW; n = 11), or 250 ml of FW containing 25 g of NBXR (n = 6), WPI (n = 11) or casein (C, n = 12) in a double-blind randomised parallel design. All assessments were repeated 1, 2, 6 and 24 hr later, and supplements were consumed at 6 and 22 hr. Outcomes – There was no difference in PIT between groups at baseline (P = 0.70). PIT decreased in all groups following ECC (P < 0.001), with no difference in the reduction between groups (P > 0.58). PIT remained suppressed in WPI, C and FW, but recovered rapidly in NBXR such that it was not different from baseline by 2hr (P > 0.05) and was greater than all other groups a 6 hr (P < 0.01) and 24 hr (P < 0.001). MS increased in all groups following ECC (P < 0.001) and remained elevated, with no difference between groups (P = 0.93). TNFα (P > 0.83) and CK (P > 0.32) did not change from baseline. Insulin increased transiently in NBXR and WPI only at 1 hour (P < 0.001), but the increases were not different from each other (P = 0.77).
Conclusion – NBXR enhanced recovery of PIT following eccentric exercise. The effect did not appear to be mediated by suppression of inflammation or MS, or by any anabolic effect of insulin. The enhanced recovery may be related to the activity of some novel peptide(s) in the hydrolysate.