Combining Whey Protein Isolate with Eccentric Training Improved Quadriceps Strength in Patients with ACL Rupture (P12-024-19)

Abstract

ObjectivesAnterior cruciate ligament (ACL) rupture results in significant quadriceps weakness, which will then cause abnormal gait and knee instability. Eccentric training (ET) can produce larger effects on muscle strength than concentric training, which may be further augmented by protein supplement. This study was to examine the effects of combining whey protein supplement with preoperative isokinetic ET on quadriceps strength and function after ACL rupture. MethodsThirty-seven male subjects aged 18–40 years with ACL rupture were randomly assigned to isokinetic ET (IET, N = 19) group or isokinetic ET with whey protein isolate (IET + WP, N = 18) group. Both groups received preoperative isokinetic ET for six weeks, containing 3–4 sets per day with 8–10 repetitions for each set, twice a week. Subjects in IET + WP consumed whey protein isolate 22 g per day. Cross-Sectional Area (CSA) of quadriceps was scanned by MRI, and strength and knee function were measured before and after the trials. ResultsAfter intervention, CSA of the involved quadriceps increased by 3.7% (NS) in IET and 7.6% (P = 0.012) in IET + WP. The ratio of side-to-side increased by 3.9% (NS) in IET and 4.8% (P = 0.002) in IET + WP. The peak torque of quadriceps during eccentric contraction at 60 degree/s, concentric contraction at 60, 180 and 300 degree/s increased by 27.9% (P < 0.001), 35.9% (P < 0.001), 34.3% (P = 0.002) and 27.3% (P = 0.003) in IET, and increased by 44.2% (P < 0.001), 42.3% (P < 0.001), 37.4% (P = 0.002) and 36.7% (P < 0.001) in IET + WP, respectively, with no differences between the two groups. Lysholm and IKDC2000 knee function score in IET + WP increased by 24.7% (P = 0.001) and 12.9% (P = 0.001). ConclusionsCombining whey protein supplement with ET tends to be more effective on improving CSA of quadriceps, knee function and quadriceps strength when compared to ET alone after ACL rupture, even though the results did not reach statistical differences. Funding SourcesThe research was supported by The National Key Research and Development Program (No.2016YFD0400603).