When calculating the daily protein needs for marathon runners or competitive weight lifters, you should allow for approximately grams of protein per kilogram of body weight

When calculating the daily protein needs for marathon runners or competitive weight lifters, you should allow for approximately 1.2 to 1.4 grams of protein per kilogram of body weight. For marathon runners or competitive weight lifters the amount of protein requirement is definitely higher than those sportsmen who does less physical amount of work. For normal people that do not require great physical activity during their normal life, then those people will obviously require less amount of protein than the sportsmen in question. so we can see that amount of protein requirement varies with the amount of physical activity that is done by the person.

This question is actually much more complex than you might think. A good estimate would be that professional sport athletes need around 0.6 to 0.8g of protein per pound of bodyweight, this can then be translated to around from 1.2g to around 1.4g  of protein per kilogram of bodyweight.

However, the complexity lies in the fact that they actually do not need much more than that, regardless of them being a weight lifter or a marathon athlete. The reason for this is that here you're reaching the upper limit of protein utilization. For that reason, weightlifters who're consuming up to 3g of protein per kilogram of bodyweight are more or less throwing it away for no reason.