If you're targeting a late October or November marathon, there's a good chance you're in it right now. Peak week. The highest-mileage, highest-stakes stretch of your entire training cycle. It's the week that makes a lot of runners anxious, and for good reason. Get it right and you arrive at the start line with genuine fitness. Get it wrong and you can unravel months of work in seven days.
Here's everything you need to know to survive it, and thrive in it.
What Peak Week Actually Is (and When It Hits)
Peak week is the training block where weekly mileage reaches its highest point before the taper begins. For most standard 16-to-20-week marathon plans, it lands roughly three weeks before race day. That means runners chasing late October and November finish lines are hitting peak mileage in early October, right now.
It's not one single magic run. It's the accumulation of your highest long run, your final quality sessions, and the total weekly load all arriving together. The goal isn't to run your best workout ever. The goal is to absorb the training, stay healthy, and set yourself up for a productive three-week taper.
The Most Common Mistake: Running Your Long Run Too Fast
This is where most runners go wrong. Peak week carries a psychological weight. You've put in months of work. You want to prove it's paying off. So you push the pace on your 20-miler, feel great through mile 15, and pay for it for the rest of the week.
Your peak long run should be run at 60 to 90 seconds per mile slower than your goal marathon pace. If you're targeting a 4:00 marathon, that's roughly a 10:10 to 10:40 pace. If you're chasing 3:30, you're running around 9:20 to 9:50. It feels uncomfortable how slow that is. Do it anyway.
The purpose of the long run at this stage is volume accumulation and aerobic stimulus, not race simulation. Running it too fast spikes physiological stress, delays recovery, and often triggers the minor injuries and immune dips that derail taper week before it even begins. Research on long-distance training consistently shows that faster-than-prescribed long efforts during peak loading correlate with higher rates of overuse injury and elevated inflammatory markers in the days that follow.
Nutrition: This Is Not the Week to Under-Eat
Carbohydrate intake during peak week needs to scale with your mileage. Many coaches and sports dietitians recommend targeting 7 to 10 grams of carbohydrate per kilogram of body weight on your highest-volume days. For a 70kg (154 lb) runner, that's 490 to 700 grams of carbohydrate daily. That's a lot of food. Most recreational athletes eat significantly less without realizing it.
The reasoning is straightforward. Your glycogen stores are being depleted at a higher rate than at any other point in training. If you don't replenish them fully between sessions, you accumulate a deficit that compounds over the week. By day five or six, you're running on empty and calling it fatigue when it's actually inadequate fueling.
Prioritize easily digestible carbohydrate sources: oats, rice, pasta, potatoes, bread, and fruit. Keep fat and fiber moderate on the heaviest training days to avoid GI issues during runs. For a deeper breakdown of carbohydrate targets across different training phases, how many carbs endurance athletes actually need is worth reading before you plan your meals this week.
Protein doesn't drop during peak week either. Aim for at least 1.6 to 2.0g per kilogram of body weight to support muscle repair between sessions. And don't neglect sodium. High sweat volume during peak week, especially in warm early-October conditions, increases electrolyte losses that affect both performance and recovery.
Sleep: The Variable That Quietly Decides Everything
You can nail your pacing, hit your carbohydrate targets, and still sabotage peak week if you're consistently sleeping poorly. Sleep is the single most underrated recovery tool in a runner's kit, and during peak week, the stakes are higher than usual.
Research consistently shows that even one night of poor sleep during high-load training elevates cortisol levels and impairs glycogen resynthesis. In practical terms, that means you wake up more stressed and with less fuel in the tank, and both of those things compound across the week. A study in the Journal of Sports Sciences found that sleep-restricted athletes showed significantly reduced time-to-exhaustion compared to well-rested controls, even when training load was identical.
Seven to nine hours is the minimum target. Many elite-level coaches push for nine to ten during peak training weeks. That may not be realistic with work and family schedules, but here's a practical approach: treat sleep as a training session. Schedule it. Protect it. Keep your bedroom cool and dark. Cut alcohol entirely this week. It fragments sleep architecture even in small amounts, reducing the slow-wave sleep that's most critical for physical recovery.
If you struggle with sleep anxiety around big training weeks, address it the same way you'd address pacing anxiety: with a process. Write down your plan for the next day the night before. It gives your brain permission to stop rehearsing logistics at 2 a.m.
Mental Strategies for the Hardest Week of Your Cycle
Peak week is psychologically demanding in ways that are easy to underestimate. You're tired. You may be doubting your fitness. You're probably thinking about everything that could go wrong on race day. That's normal.
The mental mistake most runners make is catastrophizing normal fatigue. Heavy legs on a Thursday during peak week are not a sign you've overtrained. They're a sign your body is doing exactly what it's supposed to do under a high load. The taper will address this. Trust the process you've built over months.
Break the week into individual days. Don't look at the total mileage as one intimidating block. Focus on the session in front of you, execute it at the right intensity, and close it out. Repeat. Runners who manage peak week best tend to be those who've internalized that discipline over motivation means running slower when their ego wants to run faster.
Some runners find it useful to revisit why they're running this marathon in the first place during peak week. Whether it's a personal record attempt, a first finish, or something more personal, reconnecting with that purpose helps carry you through the days when the alarm goes off at 5:30 a.m. and nothing about it sounds appealing.
What to Do If Something Goes Wrong
Here's the reality: sometimes peak week doesn't go perfectly. A minor illness surfaces. Your knee sends up a warning signal. You miss the long run because life happens. None of these scenarios automatically ruin your marathon cycle.
A missed long run three weeks out is far less damaging than forcing it through injury or illness and creating a problem that carries into the taper. Your fitness is already built. The long run in peak week is the final stimulus, not the foundation. Missing it once, managed correctly, is recoverable.
If you get sick, prioritize rest and nutrition. Don't try to squeeze in a makeup long run. Shift your mindset to taper mode early and focus on arriving healthy at the start line. If you're dealing with a physical tweak, reduce intensity immediately and consult a physio before it escalates. The runners who lose their marathon to an injury almost always waited too long to address it.
The taper period exists partly as a buffer. Three weeks of reduced mileage will absorb a setback from peak week better than most runners expect. Research on fitness retention shows that aerobic adaptations are maintained for two to four weeks of reduced training volume without significant detraining. You're not losing fitness during taper. You're converting training stress into race-ready form.
For a remarkable example of how resilience and smart training management can coexist, Paul Wilson's comeback from a shattered leg to a 160K ultra is a story worth sitting with when your own setbacks feel significant.
Strength Training During Peak Week
If you've been doing strength work throughout your training cycle, don't abandon it entirely during peak week. But do reduce it. One session of light, maintenance-focused lifting is sufficient. Avoid heavy leg work in the 48 hours before or after your long run.
The evidence supporting resistance training as a complement to marathon preparation is strong. The longevity benefits of lifting weights extend well beyond race performance, but in peak week specifically, your goal is simply to maintain the neuromuscular adaptations you've built without adding unnecessary fatigue.
Gear and Logistics: Finalize This Week
Peak week is the right time to finalize your race-day gear decisions. Wear the shoes you're racing in for your long run. Not new ones. Your trained-in shoes. If you've been considering a carbon-plated shoe for race day, the evidence on performance gains is real, and research on whether specialized running shoes actually make you faster can help you make an informed decision before committing.
Practice your race-day nutrition protocol during your long run. Whatever gels, chews, or drinks you're planning to use on marathon day, use them now. Your gut needs to be trained as much as your legs do, and GI distress on race day is almost always traced back to products that weren't practiced in training.
The Week After Peak Week: Enter Taper Correctly
When peak week ends, the taper begins. Mileage drops, intensity is maintained, and a lot of runners immediately feel worse. Taper madness is real. Legs feel heavy or strangely flat. Doubt creeps in. Minor aches that were manageable during training suddenly feel urgent.
This is normal physiology. Your body is redirecting resources from performance output to repair and adaptation. Let it. Resist the urge to run extra miles to "maintain fitness." The work is done. Your job now is to arrive at the start line healthy, fueled, and rested.
Peak week isn't glamorous. It's the hardest stretch of a marathon build for a reason. But runners who respect the process, run their long run at the right pace, eat enough, sleep like it matters, and manage setbacks without panic, give themselves the best possible chance of a strong race day. That's the whole game.