How it works

How Running Momma builds your training plan

A plain-English look at the framework behind our training plans, training paces, and race-day fueling — what we use, why we use it, and what we don't yet model.

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It's a system, not a guess

Every training plan in Running Momma is generated from a fixed framework. Same inputs, same plan — there's no language model writing it on the fly, and no randomness between runs. That's a deliberate choice: training plans should be auditable. You should be able to ask "why is this week structured this way?" and get the same answer twice.

You give us a race distance, a target date, your current running level, how many days a week you can run, and which day your long run lands on. Optionally a fitness snapshot — current weekly distance, longest recent run, or a recent race time. From there, the plan is laid out across four phases.

Four phases, each with a purpose

Periodization — splitting training into blocks that build on each other — is one of the most established ideas in endurance coaching. Your plan has four phases, and each has a job:

Reconditioning

Up to eight weeks of easy aerobic work to lay a base, if you don't already have one. Skipped entirely if your fitness snapshot already shows enough consistent volume.

Consistency

A steady hold of weekly volume with no quality work yet. The goal here is showing up — building the durability to absorb harder sessions later without breaking down.

Structured

Where the race-specific work appears — intervals, tempo, threshold, long runs with embedded effort, plus shorter neuromuscular work like strides and pickups. Each session is chosen for an adaptation we know matters at your race distance.

Taper

Volume drops, intensity stays. Three weeks for a marathon, two for a half, one for a 5K or 10K. The goal is to arrive at the start line rested but sharp.

How we set your training paces (VDOT)

Pace prescription starts with Jack Daniels' VDOT system — the framework Daniels published in Daniels' Running Formula. VDOT is a single number that captures aerobic fitness, derived from a recent race time or, if you don't have one, from your typical easy-run pace.

From your VDOT, we calculate five training paces — easy, marathon, threshold (tempo), interval, and repetition — anchored to specific percentages of your maximum oxygen uptake (VO₂max). Easy runs sit at about 59–74% of VO₂max. Threshold sits near 88%. Intervals hover around 98%. Repetitions briefly exceed it.

VDOT is a starting anchor, not a verdict. It collapses a runner into one number and has no concept of fatigue resistance or how your body actually responds. That's why your plan adapts from there.

Your plan adapts from your real runs

After every completed run we sync from your watch, the plan checks whether your real-world easy pace is meaningfully faster or slower than what it predicted. If the gap is large enough — and consistent enough — the plan recalibrates in either direction.

The trigger isn't a single fast workout. We need at least five completed easy runs before we trust a trend, and we look at the median of those runs to filter out noise. The median has to differ from the predicted easy pace by at least 10% before we do anything — small swings shouldn't ripple through the plan.

When we do recalibrate, the changes are capped: weekly distance shifts by at most 15%, VDOT shifts by at most four points, and long-run length shifts by half the volume factor. Those caps cut both ways — they apply when you're running faster than predicted (so a hot week doesn't blow up your volume), and when you're slower than predicted (so the plan dials volume down for a few weeks instead of stubbornly holding the original target).

How race-day fueling is calculated

Race-day fueling is computed from three independent models — carbohydrates, fluid, and sodium — then combined into a single timing plan. The numbers below are the published research ranges we work inside, not made-up targets.

Module Typical range Anchored to
Carbohydrates 30–120 g/h Body weight, intensity, gut training
Fluid 200–1200 ml/h Body weight, intensity, temperature
Sodium Per sweat rate × concentration Sweat rate, sweat saltiness, sports-drink intake

Carbohydrates (g/h)

Base rate scales from your body weight and strategy (recreational or competitive), then adjusts for heart-rate intensity and how trained your gut is at absorbing carbs during exercise. An untrained gut typically tolerates 35–45 g/h. A "well trained" gut can comfortably take 60–90 g/h. High-carb specialists tolerate 90–120 g/h thanks to dual-transporter (glucose + fructose) formulations.

Based on Jeukendrup (2014) on dual-transporter intake limits and Burke et al. (2018) on training-the-gut and fuel-availability strategies. See references below.

Fluid (ml/h)

Starts from a 400 ml/h baseline, adds about 6 ml/h per kg of body weight, +20 ml/h per °C above 15 °C, and adjusts for effort intensity. Final output is clamped between 200 and 1200 ml/h — beyond that you're in territory where individual variation dominates and a generic formula isn't useful. We split the recommendation 60/40 sports drink to water.

Based on the ACSM Position Stand on Exercise and Fluid Replacement (Sawka et al., 2007). See references below.

Sodium (mg/h)

We estimate sweat rate from a 0.8 L/h baseline, scaled by intensity and by +4% per °C above 15 °C, then multiply by your sodium concentration class (500, 1000, or 1500 mg per litre of sweat — "low salter", "average", or "high salter"). The sports-drink portion contributes about 400 mg/L back, so the gap is what you need to take in via tablets, capsules, or higher-sodium drinks.

Serving interval

We don't just hand you "eat 60 g/h" and leave it there. We compute how often that maps to a real serving (a 25 g gel, a chew, a scoop), adjust for your gut training and effort intensity, and round to a practical interval between 15 and 45 minutes. The point is to give you a clean watch-beep cadence on race day.

What we don't model (yet)

Honest list — these are the places where the framework doesn't yet reach, and what we'd recommend you do in the meantime:

  • Heat acclimation: we adjust your fueling for temperature, but not your pace. A hot race typically slows runners by around 3–7% per 5 °C above mild conditions. Plan accordingly on race day.
  • Altitude: no automatic correction above ~1500 m. As a rule of thumb, drop expected pace by 3–5% per 1000 m of elevation.
  • HRV / readiness: we don't ingest heart-rate variability data or modulate intensity from it. If you feel destroyed, swap the day's quality session for an easy run — the app supports it.
  • Field-tested lactate threshold: threshold pace is derived from VDOT, not from a direct field test. If you have a recent 30-minute time-trial threshold, our threshold pace is an estimate, not a measurement.
  • Cross-training load: if you swap a run for a bike or swim, we mark the session complete but don't feed the cardiovascular load back into the adaptation loop. Swaps protect your knees; they don't (yet) tighten the model.
  • Strength and plyometrics: not in scope. Run training only.
  • Individual response curves: two runners with the same VDOT get the same paces. A more personalised model based on each runner's long-term response is on the roadmap, but we're not there yet.

References

The framework above leans on a small set of well-established sports-science publications. If you want to read the source material:

Frequently asked questions

Do I need a smartwatch to use Running Momma?

No. The plan, paces, and race-day fueling all work without a watch — you can follow your sessions from your phone and mark them complete by hand. A watch helps because we use your synced runs to recalibrate the plan, but it's not required to get value out of the app.

Can I follow a plan if I've never run a marathon before?

Yes. When you set up a plan we ask for your current running level and recent volume, and the framework adds a reconditioning or consistency phase before any quality work if you need it. First-time marathoners typically get a longer ramp-up than experienced runners, with a long-run progression built around your current longest run.

How accurate are VDOT-based paces if I don't have a recent race time?

When there's no race time, we estimate VDOT from your typical easy-run pace, which is a rougher starting point. That's why the plan recalibrates from your real runs once we've seen at least five completed easy sessions. The first couple of weeks are a calibration window — paces tighten up as we learn how you actually run.

Is the race-day fueling calculator safe to follow without a nutritionist?

The carb, fluid, and sodium numbers are based on published ranges from sports-science research (Jeukendrup, Burke, ACSM) for healthy adult endurance athletes. They are general guidance, not personal medical advice. If you have cardiovascular, kidney, or electrolyte conditions, are pregnant, or take medications affecting fluid balance, talk to a clinician before following the plan.

Can I use Running Momma if I already work with a coach?

Yes — runners often use the app alongside a coach for the race-day fueling calculator, the global race calendar, and pace targets, while following their coach's sessions. You can mark workouts complete manually or sync them from your watch, and you don't have to follow the generated plan if your coach prescribes something different.

Not medical advice. The carbohydrate, fluid, and sodium guidance on this page is informational and based on published averages for healthy adult endurance athletes. Consult a clinician if you have cardiovascular, kidney, or electrolyte conditions, are pregnant, or take medications affecting fluid balance.

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