Recovery after a marathon or any form of exercise is something many overlook and neglect. This is a big mistake. Underlying injuries and the stress the body is put under needs to be attended to, bringing the balance back. If done correctly you can be back training in no time and already have a headstart on improving your next performance.
1 - 'Re-Fuel' - So you've crossed the line, checked your time, given someone a hug and patted yourself on the back in relief and pure joy after finishing your marathon. Keep moving for about 30 minutes to prevent 'blood pooling in your legs. Stay warm, even though you may be sweaty and your core temperature is high, this will drop pretty rapidly. Change into some dry clothes, wrap yourself up in the foil handouts or get some warm kit on ASAP. It's then likely you will register you are a acutely dehydrated (especially if it has been a hot day) and certainly in need of some extra nutrients. I know you are dreaming about that massive re-feed feast involving everything you've refrained from eating in the build-up to the race, but before that goes down, try adding a big pinch of Himalayan salt to your water or sports drink, and make a smoothie for after the race packed full of the essentials that will nourish your insides. My go to would be coconut water, bananas, spinach, blueberries, oats and good plant-based protein powder.
2 - 'Hot a Cold Therapy' - I'm a big fan of this treatment after seeing the results in my own performance but also after years of experimenting with athletes here in the UK and US. Spending time learning from pioneers like Brain McKenzie and Wim Hoff has unlocked a whole new train of thought to how we can speed up the recovery process and control how our body responds to these stressors. The science and research out there seems to show that when we jump from a full body Hot to Cold immersion, it improves the rush of oxygenated blood to the micro tears and other trauma of the damaged tissues helping you repair much faster. If you don't have the luxury of a sauna/hot tub and an ice bath after the race, getting in a hot shower and then switching it to cold for 1-minute intervals for a few rounds will suffice and do the job.
3 - 'More Food and Rest' - You may well be thinking of eating all the junk food you can find, but if you want to prevent putting on unwanted weight and slowing down your body, I'd always suggest re-feeding with a combination of good quality proteins, fats, and carbohydrates (I always crave sweet potatoes and a pile of veggies). Then comes the pizza. This might automatically put you into an induced 'food coma' alongside your body just needing some well-earned recovery sleep (don't set an alarm if you can and wake up when your body is ready). When you do eventually surface, get some more water on board as the body will be in need of it, and even though moving might not be what you feel like doing, getting outside for a walk or very light jog which helps get the blood flowing to the legs and provides you with the feedback you need to see what parts of the body need some attention and treatment in the coming days.
4 - 'Treat yourself to some TLC' - No matter what your level of ability, no one seems to escape the wear and tear during a Marathon in some form. The steady repetitive impact on the joints and muscles can lead to stress fractures, musculature imbalance and millions of micro tears on a cellular level. After going for a little stroll or maybe you've already struggled to get out of bed and walk down some stairs, your body will be letting you know what area's need some love. Anything from blisters to full body realignment is vital to getting you healed and back to full power. Treating yourself to a massage and getting some professional treatment from a sports therapist can not only speed up the process, it can also help you identify injuries that can then be prevented next time by adding some new prehab exercises into your program.
Be safe, run smart, have fun.