Keep moving if you can. If you come to a sudden stop at the finish line after an all out effort, there is a possibility of feeling dizzy and at times one may collapse (postural hypotension).This is because in an all out effort, the heart rate and blood pressure are very high and additionally, the rhythmic contractions of muscles while running provide an strong pump like effect on blood vessels encouraging blood to circulate back from the legs.
Stopping abruptly ceases this two mechanisms resulting in a sudden drop of blood pressure which produces dizziness and possible collapse. This can be addressed by raising the feet high.
Keep warm. Remove the cold clothes as soon as practical to stop the body temperature from dropping rapidly. Eat something as soon as you can-about 300 calories of simple carbs (some sports drink and a banana) within a half hour of finishing.Keep walking! Movement helps the heart pump fresh, oxygen-rich blood through your body. Avoid stopping or sitting for at least 30 minutes post race.
Soak the legs in a cool bath if practical for 15 or so minutes to reduce inflammation. Walk around for 10 to 30 minutes in the day. Eat small meals every two to three hours during the recovery window (period immediately after prolonged exercise, when the muscle enzymes that support glycogen production the primary fuel your muscles relied on during the race are elevated. The best foods are easily digested carbohydrates. The sooner you are able to take in these calories, the more glycogen your body will produce, and the sooner your muscles return to their normal state.
Research has shown that a little protein—post-exercise—helps your muscles absorb more glycogen (at a ratio 4:1, that means four parts carbohydrates to one part protein). During this time, when your stomach may be still a little unsettled, a good choice would be a smoothie at room temperature because—it is easily digested, has some protein, and is rich of carbohydrates.
How quickly you recover is a combination of your own unique body and how well its taken care of. Most runners will take a short slow speed run the day after a marathon This light activity helps increase blood circulation, which helps flush out metabolic waste and get oxygen and nutrients flowing to the muscles again. Get a sports massage. All week long it is a good idea to be very gentle with any stretching—and only do so after a short workout or warm-up
After the recovery run, take some time off from running. By giving your body a chance to fully and deeply recover, you can be on the road to unexpectedly fast results. This is a good time for cross training, like swimming, deep-water running, or short bike rides, so that you stay active while allowing your energy level to return to normal. Get as much ‘good’ sleep as possible. This will speed up your recovery. Once you feel recovered,start off your runs by doing slow and short runs.