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Most people sign up for a marathon and then Google what to do next. The search results are overwhelming, and the training plans all look the same from a distance. But professional runners do not train by feel or guesswork. They follow structured programs built on weekly mileage targets, controlled intensity, tested nutrition, and a taper period that lets the body recover before race day. The difference between finishing strong and falling apart at mile 20 usually comes down to how seriously you treated the 4 or 5 months before the starting line.
This is a breakdown of how professionals approach marathon preparation, pulled from established training resources and sports science guidelines.
Pick a Training Plan That Matches Your Fitness
You need a plan written for your current ability, not the ability you hope to have in 6 months. The Boston Athletic Association publishes 20-week training plans across 4 levels on baa.org, covering runners who aim for a 5-hour finish all the way down to sub-3-hour competitors. Hal Higdon’s advanced plans on halhigdon.com start long runs at 10 miles in week 1 and peak at 20 miles, hitting that distance 3 times in weeks 11, 13, and 15.
A common mistake is selecting a plan that is too aggressive. If you have never run more than 15 miles in a week, a program built for someone logging 50 is going to put you in a physical therapy office. Be honest about where you are starting.
The 80/20 Split and Why Slow Running Matters
Professional runners spend about 80% of their weekly mileage at an easy, conversational pace. The remaining 20% goes to moderate and hard efforts like tempo runs, intervals, and race-pace sessions. This ratio is well supported in endurance training literature, including research published in Sports Medicine (Springer, 2025).
Running slow feels counterintuitive when you are training for a race, but easy miles build aerobic capacity without overstressing your joints and tendons. The hard sessions teach your legs and lungs to handle faster paces, but they need to be surrounded by recovery. If every run feels hard, you are doing it wrong, and you are probably headed toward injury.
What Goes in Your Pocket on Race Morning
Fueling during a marathon requires planning weeks before the race itself. ACSM recommends 30 to 60 grams of carbohydrates per hour for long-distance efforts, and most runners test products during training to find what their stomach tolerates. Options range from chews like Clif Bloks to liquid carbohydrate options such as Maurten Gel 100 or traditional gels from brands like Science in Sport.
Carry what you have rehearsed. Nothing new on race day is a rule that holds because gut distress at mile 18 can undo months of preparation.
Hydration Has Numbers Behind It
ACSM recommends drinking 5 to 12 ounces of fluid every 15 to 20 minutes during a marathon. They also recommend 300 to 600 milligrams of sodium per hour to replace what you lose in sweat. Before the race, the guideline is 5 to 7 milliliters per kilogram of body weight at least 4 hours out from the start.
These numbers mean something practical. If you weigh 70 kilograms, that is roughly 350 to 490 milliliters of fluid in the hours before the gun goes off. Sodium tablets, electrolyte drinks, and salted snacks are all fair game during training runs where you are testing your race-day routine.
Dehydration and overhydration can both cause problems. Practice your fluid intake during your longest training runs so you know what your body actually needs.
The 3-Week Taper
After weeks of building mileage, professional plans pull back volume in the final 3 weeks before the race. Hal Higdon’s advanced plans follow this approach after peaking at 20 miles. The taper reduces total mileage by roughly 20 to 30% each week while keeping a few short, faster efforts to maintain leg speed.
This is the period where runners feel restless and anxious because they are running less. That feeling is normal. Your body is absorbing the training you already did. Trying to cram in extra miles during the taper because you feel guilty about resting is one of the fastest ways to show up on race morning with heavy, tired legs.
Sleep, Strength Work, and the Stuff Nobody Posts About
Professional runners sleep 8 to 10 hours a night during heavy training blocks. They do strength work 2 to 3 times a week, focusing on hips, glutes, and core stability. They foam roll. They stretch. None of this is exciting, and none of it makes for good social media content, but it prevents the overuse injuries that sideline amateur runners mid-program.
If you are going to commit 20 weeks to a training plan, commit to the boring parts too. Get to bed earlier. Do your single-leg squats. Spend 10 minutes on a roller after your runs. These things compound over months.
Race Week Itself
Keep race week simple. Eat familiar foods with a higher carbohydrate ratio in the 2 to 3 days before the race. Lay out your gear the night before. Know the course, the weather forecast, and where the aid stations are.
Run the first 10 miles at a pace that feels too easy. If it feels comfortable at mile 10, you planned it right. The marathon does not really start until mile 20, and the runners who went out too fast are the ones you will pass in the final 10 kilometers.
