Protein intake is essential for muscle recovery, a process necessary as a consequence of activity in everyday life and, even more importantly, from muscle breakdown induced by exercise. But why do muscles need protein? And why is it important to understand your daily protein requirements?
When a muscle is put under stress, it creates micro tears on the muscle surface. The degree of the tear within the muscle is dependent on the level of stress put through the muscle. The highest amount of stress on both the muscle and joints comes from sports such as powerlifting and bodybuilding, where the results are often dependent on the loads lifted and consequential hypertrophy and strength gains. If the stress being exerted by the weight (or other stimulus) exceeds your muscle strength, then this can often lead to excessive muscle tears and injuries to both muscles and joints.
Why do the muscles need protein?
With this in mind, it becomes transparently clear, that there needs to be an antagonistic rebound process to in place to compensate for the muscle damage and lead to muscle recovery. One important aspect of ensuring your muscles recover, among many,is sufficient dietary protein.
In simple terms, it’s the combination of both rest, protein and overall caloric intake that leads to muscle recovery, muscle hypertrophy and – training stimulus dependent – increases in strength.
From a more granular look into this; when you consume protein it is converted into amino acids during the digestive process. Amino acids are the smallest molecular unit of protein. From here the 20 amino acids can be transported and used for various different processes ranging from hormone creation to rebuilding tissues within the body, such as muscle, skin and hair.
The amount of protein required differs hugely from person-to-person, largely dependent on goals, current body size/body composition, training volume/training intensity, disease and ailments and gender. The upper limit of protein intake, suitable for individuals pursuing muscle growth is 2.2g per kg of bodyweight. The lowest amount is set within the government RDA, within the UK, the protein RDA is as little as 0.36g/lb of bodyweight. This is an intake amount suggested for someone who is completely sedentary and should be viewed as the absolute bare minimum.
If your protein intake is not in alignment with your training intensity and volume then you won’t hit your training goals, especially if they’re centered around gaining strength or increasing muscle mass.
Muscle-centric goals to one side; lack of protein can also lead to other health complications, including hair loss, skin issues and increased hunger.
Can you consume too much protein?
Although high-protein diets have risen in popularity – leading to the ever-increasingly success of the supplement industry – they have also been scrutinized. This is due to claims that high protein intake can lead to kidney damage, with particular reference drawn toward causing chronic elevation in hyperfiltration and glomerular pressure.
Martin, Armstrong and Rodriguez (2005) study (meta-analysis) aimed to examine this hypothesis. One student within the analysis (1) 65 subjects were split into two group: a high-protein diet group and a low-protein diet groups for 6 months. The results concluded that although the high-protein group experienced both increase GFR and kidney size, renal function as a consequence to a high-protein diet was not impaired.
Poortsmans and Dellalieux went one step further with this toward the athlete domain. A sub-culture of individuals notorious for adhering to a protein rich diet for recovery purposes. Their study (2) examined renal function of 37 athletes who regularly consumed between 1.4g-1.9g/kg/day and concluded that this did not impair renal function.
The two key takeaway messages from this article are:
1) Protein is essential for muscle and all bodily tissue recovery
2) An excess of protein intake above the recommended daily allowance doesn’t appear to impact renal function
However that said, too much of anything is often a bad thing and protein intake should be no different. Protein contains 4 calories per gram and therefore protein intake – although likely not detrimental o renal function – may be detrimental to the waist line if calorie consumption is not monitored.
1) Skov AR et al. Changes in renal function during weight loss induced by high vs low-protein low-fat diets in overweight subjects. Int J Obes Relat Metab Disord. 1999;23:1170–1177.
2) Poortmans JR, Dellalieux O. Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sport Nutr Exerc Metab. 2000;10:28–38.