[Effect of dietary supplements and whey protein on muscle mass and strength of the operated limb after anterior cruciate ligament reconstruction: a systematic review].

Muscle weakness and atrophy of the quadriceps muscle after anterior cruciate ligament reconstruction may persist for up to 6 months after surgery and cause re-injury to the ipsilateral or contralateral limbs. Many authors state that adequate nutritional status during the rehabilitation period can contribute to faster postoperative recovery of muscle mass and strength of the lower limb, be an adjunct to exercise, or serve an alternative treatment strategy. The purpose of the research was to conduct a systematic review of the literature and evaluate the degree of influence of dietary supplements on muscle mass and strength of the operated limb after reconstruction of the anterior cruciate ligament (ACL). Material and methods. The search for articles was carried out in international databases PubMed, Google Scholar, Cochrane Library. The time frame of the search was 22 years. To be included in the review, studies had to meet the PICOS criteria: participants were men and women over 18 years of age after ACL reconstruction; intervention - supplementation after and/or before and after ACL reconstruction; comparison - placebo group or no supplementary interventions; results - assessment of the dynamics of changes in muscle mass (cross-sectional area, muscle thickness or size of skeletal muscle fibers) and / or maximum strength (dynamic or isometric) of the operated limb; research design - randomized controlled trials (RCT). The quality of selected RCTs was assessed using the Cochrane Collaboration Risk of Bias (RoB 2) tool. Results. A total of 1397 articles were found after searching in the databases. This systematic review included 6 RCTs with a total number of patients 186. The following dietary supplements were used: leucine - 1 article, glucosam ine - 1 article, creatine - 1 article, vitamins E and C - 2 articles. One study evaluated the effect of whey protein supplementation in combination with neuromuscular electrical stimulation on isometric strength of the operated limb. When comparing the data of 3 groups in the pre- and postoperative periods, there were no statistically significant differences between the groups. When considering the protocols for taking dietary supplements based on creatine, glucosamine, vitamins E and C, none of the studies demonstrated statistically significant improvements in the parameters of maximum strength or muscle hypertrophy of the operated limb in the main groups compared with the control groups. Also, no results have been obtained indicating that these dietary supplements can slow down muscl e atrophy after surgery. In another study that evaluated the effect of leucine supplementation, by the end of the rehabilitation program, the muscle strength of the operated limb tended to increase more in the leucine group than in the placebo group, but without a statistically significant difference. At 10 cm from the patella, the femoral circumference of the operated limb in the leucine group increased more than in the placebo group, and the differences were statistically significant (р=0.009). Two studies were rated as high risk of bias, three as moderate risk, and one as low risk. Conclusion. None of the supplements used had a statistically significant effect on the muscle strength of the operated limb after ACL reconstru ction. In terms of thigh muscle hypertrophy, the only significant improvement was associated with leucine supplementation and an increase in thigh circumference at a distance of 10 cm from the patella.