A new study found additional benefits of consuming a blend of soy and dairy proteins after resistance exercise for building muscle mass (J Appl Physiol. 2014 Apr 3. [Epub ahead of print]). The research found that using a protein blend of soy, casein and whey post-workout prolongs the delivery of select amino acids to the muscle for an hour longer than using whey alone. The study also showed a prolonged increase in amino acid net balance across the leg muscle during early post-exercise recovery, suggesting prolong muscle building.
The double blind, randomized clinical trial included 16 healthy participants between the ages of 19 and 30 to assess if consumption of a blend of proteins with different digestion rates would prolong amino acid availability to lead to increases in muscle protein synthesis after exercise. The protein beverages provided to study subjects consisted of a soy-dairy blend (25 percent isolated DuPont Danisco SUPRO soy protein, 50 percent caseinate, 25 percent whey protein isolate) or a single protein source (whey protein isolate). Muscle biopsies were taken at baseline and up to five hours after resistance exercise. Both groups ingested the protein sources one hour after exercise.
The study demonstrated that consuming a soy-dairy blend lead to a steady rise in amino acids and that the soy-dairy blend yielded an increase in select amino acid delivery for about an hour longer than whey protein alone. The blend also sustained a greater positive net amino acid balance, compared to whey, suggesting there is less muscle protein breakdown during the time period shortly after consumption of a blended protein product.
The study was conducted by researchers from the University of Texas Medical Branch in collaboration with DuPont Nutrition & Health.