Updated: Apr 10, 2020
Strength Athletes 0.8-1.4g/kg/day
Endurance Athlete 1.6-1.8g/kg/day
To explain this better the formula is grams of protein per kilogram bodyweight per day.
There is major differences between the two forms of training. The common belief is Strength Training requires more protein intake than Endurance Training. This is not true, Endurance Training actually requires more protein intake. Strength Training targets specific area or group of muscles whereas Endurance Training causes muscles to undergo whole body protein turnover, Strength Athletes undergo major skeletal muscle protein turnover.
This is completely different, whole body compared to skeletal muscle turnover. It would seem that the person who's trying to gain muscle get bigger should have the protein intake but that's just not the case, this is what makes fitness sciences so interesting.
The goal of protein intake is to supplement the turnover (replace the recycled proteins). This also causes nitrogen balance in the body, Proteins can be processed by the body at 24-26g per sitting. Then the body has the ability to process 8-10 grams of protein per hour. Nitrogen balance is gained by consumption of protein because protein is majority nitrogen. Endurance athletes need their muscles repaired whereas strength athletes need proteins for hypertrophy and maintenance.
Another common misconception is too much protein causes liver damage, this is also just not true. When protein is consumed in excess (more than 24-26g per hour), the body drops the amine group in the proteins, and the proteins are oxidized which means used for energy. This sounds good but keep in mind protein holds very little energy compared to the other macronutrients, which makes protein a pour source of energy in comparison. Protein is made up of amino acids, hence why the body drops the amine group.