How to Train for a Marathon If You Do F45

F45 builds something genuinely useful for marathon training. The cardiovascular conditioning, the functional strength, the ability to keep moving under fatigue. If you have been attending three or four times a week consistently, you are not starting from zero. You are starting from a solid base.

But marathon running has demands that F45 circuits do not address. Long sustained aerobic effort. Progressive weekly mileage. Pace discipline at low intensity. None of that is what happens in a 45-minute circuit session where every interval is near maximum effort.

The combination is powerful when it is managed well, and that is exactly where most F45 regulars go wrong. They add marathon training on top of their existing F45 schedule without changing anything, and within four to six weeks they are injured, exhausted, or both.

Edge is a hybrid training app built specifically for people who do multiple types of training and need a single plan that integrates them. For F45 regulars training for a race, Edge builds a programme that treats your sessions as part of your total weekly load and programmes your running around them. You do not have to figure out the balance manually. That is what the app is for.

Does F45 Count as Marathon Training?

Partially, and in different ways than most people expect. F45 cardio days, particularly the running and cycling intervals, build genuine aerobic capacity that transfers to road running. The strength days build the glute, hamstring, and core resilience that keeps your form intact in the later stages of a race.

What F45 does not build is the specific adaptation needed to sustain effort for two to five hours. Marathon fitness is built through long, moderate-effort running done repeatedly over many weeks. Zone 2 aerobic conditioning. Progressive long runs. These are fundamentally different stimuli to circuit training, regardless of how hard the circuits are.

Think of your F45 sessions as your strength and conditioning base. Think of your additional runs as your race-specific layer. Edge is the system that connects both into one weekly plan, so you are never guessing which days to run, how far to go, or whether yesterday's F45 session was too much before tomorrow's threshold run.

How Many F45 Sessions Should You Keep?

For most people training for a marathon, three F45 sessions per week is the upper limit. Two is more manageable. The reason is not that F45 is harmful. It is that F45 sessions are high-intensity and generate significant muscular fatigue. When you are also building weekly running mileage, the cumulative load adds up fast.

The sessions that matter most to keep are the ones you genuinely enjoy and the ones that complement your running rather than compete with it. F45 strength days are particularly valuable because they build the leg resilience and core stability that prevent running injuries. Cardio days are more interchangeable with running and can be reduced first if you need to drop frequency.

As your long runs grow beyond 22km and total weekly mileage climbs toward 55 to 65km, dropping to two F45 sessions becomes important. In the final three weeks before race day, one session per week is sufficient. The priority shifts to arriving healthy, not staying fit. You are already fit by then.

The Weekly Schedule That Actually Works

This is a template week built around three F45 sessions and three runs. When you use Edge, this structure is built automatically around your specific session days, goal race, and current fitness. But this gives you the framework and the logic behind it.

The logic is simple: F45 sessions cluster mid-week, runs fill the gaps and bookend the weekend. Monday protects recovery from the long run. Friday becomes flexible as mileage grows. Edge manages this automatically so you are never looking at a blank week trying to work out where everything fits.

The 16-Week Build: Phase by Phase

Sixteen weeks is the standard block for marathon preparation from a fitness base. For F45 regulars the phases are slightly different to a standard plan because you are managing both F45 load and running volume simultaneously. Edge handles this progression automatically.

Why F45 Plus a Generic Marathon Plan Does Not Work

The most predictable failure pattern: an F45 regular signs up for a marathon, finds a 16-week Hal Higdon plan online, and starts following it alongside their existing three or four F45 sessions per week. By week four they are sleeping badly. By week six something in their knee or shin starts complaining. By week nine they either drop F45 or drop the race.

Generic marathon plans are designed for people who only run. They programme four or five running days per week and assume those are your only training days. When you are also doing three F45 sessions, you are doing seven or eight hard training sessions per week. That is too much for almost anyone.

Edge solves this at the structural level. It builds one integrated programme where your F45 sessions and your running are both accounted for, load-managed together, and progressed toward your race date as a single plan. It is not a running app that ignores your circuits. It is a hybrid training platform that understands you do both and builds accordingly.

For F45 regulars, this means the running is always scheduled around your sessions, never on top of them. Your recovery days are protected. Your long run is never 24 hours after a hard circuit session. The things that cause most hybrid athletes to break down are handled before they become a problem.

F45 Cardio Days vs Strength Days: What to Prioritise

Not all F45 sessions are the same for marathon training purposes, and knowing which to prioritise matters as mileage increases.

F45 strength days, typically the Monday, Wednesday, and Friday sessions at most studios, build the posterior chain, glute, and core strength that directly supports running economy and injury prevention. These are the sessions most worth keeping throughout your training block. Strong glutes and a stable core mean better form at kilometre 35 when your body wants to fall apart.

F45 cardio days, the Tuesday and Thursday sessions, overlap more with what running already provides. As your weekly running volume grows, these become more interchangeable. If you need to drop a session to manage total load, a cardio day is the right one to sacrifice. You are already building cardiovascular fitness through your running.

Running Pace: The Biggest Adjustment F45 Athletes Need to Make

F45 trains you to push hard. Every session is high effort by design. The format rewards intensity. That is part of why F45 works so well for general fitness and why F45 regulars tend to be fitter than average when they start marathon training.

It is also why F45 regulars almost universally run their easy days too fast. When you are used to training at 80 to 90% of maximum heart rate, running at 60 to 65% feels like you are barely moving. Most F45 athletes describe their first Zone 2 runs as frustratingly slow. That feeling is accurate. You are running slower than feels natural.

Run it anyway. The aerobic adaptations that come from sustained Zone 2 effort are the foundation of marathon fitness. They are what allow you to hold pace for four hours without glycogen crashing or form collapsing. Edge prescribes your runs by effort zone rather than just pace, which helps F45 athletes calibrate easy days correctly regardless of how fit they are.

Half Marathon vs Full Marathon: How the Approach Differs

If your goal is a half marathon rather than a full, the F45 balance is considerably more manageable. Half marathon training peaks at around 45 to 55km per week. That volume is sustainable alongside two to three F45 sessions throughout the block without the fatigue accumulation that appears in full marathon prep.

For a half marathon, a 12-week build works well. Long runs peak at 18 to 21km. You can likely keep three F45 sessions per week through most of the block, dropping to two in the final four weeks and one in the final 10 days. Edge builds this programme automatically based on your race type and goal time.

For a full marathon, follow the 16-week framework above. The higher peak mileage is where the interaction with F45 intensity becomes most critical to manage, and where having a structured plan that accounts for both becomes genuinely important rather than just useful.

Nutrition When F45 and Marathon Training Overlap

The caloric and nutritional demands of combining F45 with marathon training are significant and consistently underestimated. A 45-minute high-intensity F45 session burns 400 to 700 calories. A 28km long run burns 1,800 to 2,400 calories. In a week that includes three F45 sessions and four runs including a long run, total energy expenditure can be 40 to 60% higher than a normal training week.

Underfuelling in this context is not a minor inconvenience. It causes persistent fatigue, suppressed immune function, hormonal disruption, increased injury risk, and declining performance across both F45 and running. It is the most common reason hybrid athletes plateau or break down mid-block.

• Carbohydrate is not optional. On long run days and the day before, rice, oats, pasta, and potatoes should be a deliberate part of your meals. Your muscles run on glycogen and depletion compounds across the week.
• Protein matters most after F45 strength sessions. Aim for 30 to 40g within 90 minutes of finishing to support muscle repair and adaptation.
• Fuel your long runs actively. Once runs exceed 75 minutes, take on 30 to 60g of carbohydrate per hour. Do not wait until you feel tired.
• Sleep eight hours. This is not optional during peak training weeks. Adaptation happens during sleep. Cutting it short by even an hour per night compresses the most important part of the training process.

Frequently Asked Questions

Can I do F45 the day before my long run?

Ideally not. An F45 session the day before your long run means your legs will carry fatigue into the most important session of your week. Edge automatically spaces your F45 days and your long run so this conflict does not happen. If your schedule forces it, choose a strength-focused session over cardio and keep your effort controlled.

Should I quit F45 during marathon training?

No. You do not need to quit F45 to train for a marathon. Two to three sessions per week is sustainable alongside marathon prep for most of the block. The key is treating those sessions as part of your total weekly load rather than something separate, which is exactly how Edge programmes your week.

F45 has running in some of its sessions. Does that count toward my weekly mileage?

The cardiovascular benefit counts and Edge factors the session intensity into your weekly load. But the running intervals in F45 sessions are short, high-intensity, and not sustained. They do not build the aerobic endurance that comes from long easy runs. Edge treats F45 sessions as high-intensity cross-training rather than running mileage.

I have been doing F45 for two years. How fit am I going into marathon training?

Fitter than most people who start marathon training from scratch. Your cardiovascular system is well developed, your legs are strong, and your body is used to regular hard training. You will likely find the early weeks of a marathon block feel manageable. The challenge comes at higher mileage when total load increases. That is where structured planning matters most.

What is the difference between Edge and just following a marathon plan I find online?

A standard marathon plan does not know you do F45. It programmes five running days per week without accounting for the fact that three of those days you are already doing high-intensity circuit training. Edge builds one integrated plan where your F45 sessions and your running are both present, both counted, and both progressed together toward your race date.