Utilizing Fast and Slow-Absorbing Proteins for Muscle Repair & Growth
Lewis Chan, HK BioTek Intern
Are you taking the right amount of proteins at the right times of day?
The type of protein you take as well as the time of day you take your protein can help you utilize their muscle-building or muscle-repairing abilities to their full potentials.
One factor determining your choice of protein is whether it gets absorbed quickly or slowly into your body.
Fast-absorbing proteins, such as whey and soy protein, facilitate muscle gain. These proteins are easily digestible by the body—it takes just 2 hours to fully absorb a 20-gram dose of whey protein.
After a strenuous workout, your muscles undergoes hypertrophy, the process where the body produces new muscle fibres to help repair and replace damaged ones. As more fibres are produced to fuse with damaged ones, the body requires an adequate supply of protein to provide the body with amino acids for recovery and repair. These processes will allow you to gain muscle mass.
To facilitate muscle repair, the International Society of Sports Nutrition (ISSN) recommends a dosage in the range of 1.4 to 2.0 grams of protein per kilogram of body weight per day for building muscle mass and for maintaining muscle mass through a positive muscle protein balance. Both plant and animal sources of fast-absorbing proteins are able to provide the body with amino acids to rebuild muscle.
Slow-absorbing proteins such as casein provide the body a constant supply of amino acids throughout a longer period of time, typically 4 to 5 hours. Taking more time to digest means that casein is able to provide the body with a slow and steady release of amino acids rather than releasing them quickly.
To facilitate muscle repair, the ISSN recommends 30 to 40 grams of casein protein before bed. This will help provide increases in muscle protein synthesis and metabolic rate without influencing lipolysis (fat breakdown to release fatty acids). Your muscles won’t have enough time to heal in a single night, but giving your body what it needs to repair itself is a step towards the right approach.
As always, consult your doctor or nutritionist for more specialized advice if you are looking to gain muscle or have experienced any muscle-related injuries.
Jäger, R., Kerksick, C.M., Campbell, B.I. et al. (2017) International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 14, 20. https://doi.org/10.1186/s12970-017-0177-8