You may feel like collapsing right after a long and strenuous race. Firstly, what you should do after the finish line is drink water or a sports drink with electrolytes to replenish fluids.
A lot of experienced runners or sports medicine doctors say that it is vital to consume a combination of carbohydrates and protein after a long race to speed up recovery or be ready for the next race, and so that you reduce your chance of injury and soreness. In general, the best time to restore energy and rebuild your muscles lost during the race is believed to be within the first 20 to 30 minutes after the race.
Your body needs essential nutrients especially after a hard workout to repair the muscle tissues and help restore energy. It is advisable to give a good supply of carbohydrate and protein, ideally, in an approximate 4:1 ratio.
Carbohydrate is a main source of energy which is stored as glycogen in the muscles and liver. A bunch of bananas will provide your body with carbohydrate and potassium to prevent muscle cramps. (e.g. pasta, bread, rice and the like)
Refueling depleted muscles with a decent meal can reduce muscle soreness soon after the finish line. Thus, it is recommended that you consume protein such as meat, fish, beans, etc to enhance muscle reparation and glycogen replacement.