Protein. THE macronutrient when it comes to anything muscle related. But the current literature on its effects on strength are not as clear as hypertrophy. If you mostly care about strength adaptations, does more protein lead to more strength or should not really bother?
What did they test? The authors reviewed the current available literature to explore the effect of protein on muscle strength and whether there is a potential dose response relationship between the two.
What did they find? Protein was effective at increasing muscle strength only when combined with resistance training with an intake of 1.5g of protein per kilogram of body weight being the optimal intake for strength increases.
What does it mean for you? Given the current literature on protein intake and hypertrophy, consuming roughly 1.5g of protein per kilogram of body weight should allow you to optimize gains in muscle mass and strength.
What’s the Problem?
Protein is probably the most “loved” macronutrient in the world of fitness. We constantly hear about how bad carbs or fats can be for health and body composition but the one thing you rarely hear is anyone talking bad about protein. You may occasionally hear the ol’ “protein is bad for your kidneys” fear-mongering mumbo jumbo from people who are not really involved in fitness but science has shown that high protein intakes won’t harm your kidneys if you’re a healthy individual 1. There have even been studies exploring the effect of up to 400g of protein per day on various health markers and finding no real harm from such extreme intakes 2.
Protein is an important component of any diet that aims at improving body composition as it can help one maximize muscle mass gain when gaining weight and maximize muscle retention when losing fat 3. Additionally, higher intakes of protein can boost recovery from all kinds of physical activity and potentially lead to increases in various types of performance 4.
The current Recommended Daily Allowance for protein is around 0.8 grams per kilogram of bodyweight. For increases in muscle hypertrophy an intake of 1.6-2.2 grams of protein per kilogram of bodyweight has been shown to be a generalisable optimal range with recent meta-analytical work pointing more to the lower end of the range 5. Protein and resistance training are definite “match” as far as synergy for promoting significant increases in muscle hypertrophy 6 and supplementation of protein can often be a “game changer” in one’s diet when trying to make significant muscle gains.
Previous literature has examined the dose-response relationship of protein with muscle mass but it is still not really clear whether higher protein intakes can further increase muscle strength and whether there is a dose-response relationship between protein intake and muscle strength.
Several individuals engage in resistance training to increase muscle strength with muscle hypertrophy coming as a secondary goal, especially those who are recreationally engaging in any form of strength sport (recreationally or competitively) or any type of “traditional” barbell-based strength training (eg: starting strength, stronglifts 5x5 etc). Understanding whether more protein can lead to more strength is important not only for the above population but also for individuals seeking to mostly reap a lot of the health benefits that resistance training has to offer, which may only require about an hour of training per week 7. If the “optimal” range of protein for strength lies somewhere closer to the lower end of the “optimal” range for protein intake and hypertrophy then the above populations and those who seek to maximize hypertrophy may find themselves in a “two birds with one stone scenario” as far as protein consumption goes (although REPS does not condone any sort of bird hunting with stones).
Let’s see if this meta-analysis by Tagawa et al (2022) has the answers we seek!