Not all proteins are created equally. The over and above the quantity of protein the delivery, composition, digestion and absorption kinetics can differentially affect the postprandial anabolism which has been previously discussed here. Indeed, at a recent conference we presented the effect of a low-quality protein supplement vs. a high-quality whey protein supplement on postprandial measures of muscle protein synthesis, dosed and delivered in the same manner following a resistance training session.
Optimising muscle adaptation during exercise training is a key component for longitudinal development. Certainly, the robust observations made following a single protein feed suggest choosing higher quality fast acting protein sources is advantageous. However, the effects of long-term protein supplementation on measures of muscle development are more nuanced.
Confounding variables such as dietary intake, timing and distribution, compliance, physical activity, sedentariness and sleep are relatively easy to control during short-term studies, however, over a long period of time adequately controlling all these factors in humans is nigh on impossible. Additionally the dissociation between acute measures of muscle protein synthesis and long-term measures of muscle development is another likely source of variation.
Recent technical advances have allowed long-term measures of muscle protein synthesis to be obtained under ‘free-living conditions’ (i.e. incorporating postabsorptive, postprandial, active and inactive periods, hormonal, diurnal and other temporal cycles). Indeed, recent studies in older men and women have shown long-term anabolic effects for protein supplementation with resistance training. However, the effect of long-term supplementation in young, healthy subjects is unknown. The Healthy Aging and Performance Nutrition (HAPN) team of Food Health Ireland (FHI) in PESS recently sought to investigate the effect of dietary protein supplementation combined with resistance training on long-term integrative measures of muscle protein synthesis. In this study we show divergent responses between supplement (singular) and supplementation (plural) strategies demonstrating that there is ‘room at the top’ to improve dietary protein provision. And whilst we can only deduce what the best or most optimal supplementation strategy might look like, what we can conclude that simply reaching a large daily protein quota (2.0 g/kg in this study) any which way probably won’t work.
Robert Davies is a Research Assistant in Exercise Physiology in the Department of Physical Education and Sport Sciences at the University of Limerick. You can contact Robert via email at Robert.Davies@ul.ie.