Training hard without compromising your immune system? Just double your protein intake...
Athletes who want to keep training hard during the corona crisis may not want to use anabolic steroids. We wrote this yesterday. Today we want to tell you what athletes can do if they want to protect themselves against nefarious viruses. We base ourselves on a humane study of Scottish sports scientists from 2014. The Scots discovered that an increase in the amount of protein in the diet counteracts the negative effect of intensive physical exertion on the immune system.
The researchers experimented with 8 well-trained cyclists. On 2 different occasions, the subjects had to train considerably more than usual for a week. In these weeks, training volume increased by as much as 70 percent. A rule of thumb is that athletes who don't want to disrupt their immune systems can increase their training volume by just 5 percent per week.
Physical activity in itself is good for the immune system, but very intensive physical exertion temporarily lowers the immune system's effectiveness. The researchers wondered if they could do something about this by increasing the protein content of the athlete's diet.
So the Scots gave the subjects 1.6 grams of protein per kilogram of body weight per day one week, and the next week 3 grams of protein per kilogram of body weight. The extra energy of the proteins was at the expense of energy from fat.
During the intensive workouts, the amount of white blood cells [leukocytes, in other words: all immune cells] in the athletes' blood decreased. This specifically happened with the amount of granulocytes in the blood. You can think of granulocytes as the grenades and land mines of the immune system. Additional protein in the diet reversed the decline in both cases.
The amount of CD8 + T cells in the athletes' blood decreased both during the intensive workouts and during the first hour afterwards. If granulocytes are the immune system grenades and land mines, then CD8 + T cells are its soldiers. And yes - this decrease was offset by an increase of the protein content of the diet.
The effects discovered suggest that unusually intensive training increases the chance of an infection with a virus or bacteria - but that extra proteins keep the immune system up. And that's exactly what happened.
During the extra-intensive training week with a normal protein intake, the subjects reported more symptoms of upper respiratory tract infection - but not during the extra-intensive training week with a high protein intake.
Brain Behav Immun. 2014;39:211-9.
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