What training split is best for hybrid athletes?

Upper/lower run four days is the usual answer, because it hits each muscle twice a week and leaves three days clear for endurance work. Frequency has a negligible relationship to hypertrophy once volume is equated, so the split that leaves room for your running is the better split.

How many sets per muscle should I program?

Twelve to twenty fractional sets per muscle per week with no endurance training, twelve to fifteen at four to six endurance hours a week, and ten to fourteen above seven hours. Fractional means direct sets counted in full and indirect sets at half.

What rep ranges should I use?

Five to ten on compounds at 2 to 3 reps in reserve, and eight to twenty on isolation work at 0 to 1 RIR. Anything from five to thirty reps builds muscle when taken close enough to failure, so the rep range is not the limiting variable — the effort is.

Can I import an existing program?

You build the split and exercise list once in the editor, including rep ranges and RIR targets per movement. After that the app runs it — the progression rule decides loads and the ghost values pre-fill from your last session.

Should I change my program when I add running?

Usually yes, by reducing volume rather than by changing the split. Adding endurance without subtracting lifting volume is the most common structural error in hybrid training, because the fatigue has to come from somewhere and if it does not come out of the programme it comes out of your sleep or your joints.

The Program Editor: Splits, Rep Ranges and RIR Targets

The split matters less than you think

Frequency has a negligible relationship to hypertrophy once weekly volume is equated. That single finding from the volume dose-response literature does most of the work: training a muscle twice a week versus four times does not matter per se. It matters only because it changes how much quality volume fits in a week — twenty-five hard sets in one session are not twenty-five hard sets.

So the criterion becomes practical: pick the split that leaves room for your endurance work.

Split	Lifting days	Endurance room	Verdict for hybrid
Full body ×2–3	2–3	Excellent	Best during a race block
Upper/lower ×4	4	Good	The default for most hybrid athletes
Push/pull/legs ×6	6	Almost none	Two lower-body days plus running is a lot of legs
Bro split ×5	5	Poor	Low frequency per muscle and a high day count

Upper/lower run four days is the default because it hits each muscle twice, leaves three days clear, and its lower-body days can be spaced away from hard running.

The volume decision

This is the one that actually needs your endurance load as an input.

Endurance load	Fractional sets/muscle/week	Honest expectation
None	14–20	Full hypertrophy potential
1–3 h/week	12–18	Essentially unaffected
4–6 h/week	12–15	Slower, still real
7+ h/week	10–14	Strength maintenance, not growth

Fractional means direct sets in full plus indirect sets at half — the model that best fit the dose-response data across 67 studies. A row is one direct set for the lats and half for the biceps.

The failure mode is adding endurance without subtracting lifting volume. The fatigue has to come from somewhere, and if it does not come out of your programme it comes out of your sleep, your joints or your next block. The counting.

Rep ranges and RIR targets, per movement

Set once per exercise, and the difference between movement types is the part that matters:

Movement type	Rep range	RIR target	Why
Compound	5–10	2–3	Failure here costs disproportionate systemic fatigue
Isolation	8–20	0–1	Cheap to recover from; the last reps are where the stimulus lives

Anything from five to thirty reps builds muscle when taken close enough to failure — the rep range is not the limiting variable. Proximity to failure is, and the relationship is non-linear: within roughly 0 to 5 RIR, closer is modestly better, and above about 5 RIR hypertrophy falls off steeply. A set at 6 RIR is not a low-quality working set; it is a warm-up.

For a hybrid athlete the compound target matters more than for a pure lifter, because the systemic fatigue from a set taken to failure has a second claimant. Two to three RIR on compounds is not conservatism — it is what leaves the squat session recoverable alongside Thursday's threshold run.

Ordering within a session

Two rules worth encoding when you build the list.

Compounds first, while you are fresh. The exercises with the highest technical demand and the highest systemic cost go where you can execute them.

Movements that share tissue with your key endurance session go last, or on a different day. If Thursday is a hard running day, Wednesday's session should not finish with heavy Romanian deadlifts.

Rest, prescribed rather than felt

Two minutes or more on compounds, one to two on isolation.

The Bayesian meta-analysis on inter-set rest finds that ninety seconds captures nearly all the benefit and under sixty is clearly worse. Short rests do not make a session more efficient; they make it a different session, with lower loads and more metabolic fatigue.

For a hybrid athlete this is worth respecting for a second reason: a rushed lifting session with short rests is a session with a cardiovascular cost you did not budget for, on top of the endurance work you already scheduled.

Editing mid-block

The editor is deliberately not something you touch often. Changing exercises mid-block breaks the per-exercise history that the progression rule and the e1RM trend are built on.

When to edit anyway:

Endurance volume changed materially. Move down a volume tier.
An exercise is causing pain. Swap it, and accept the history restart.
A movement has stalled for three weeks with RIR above 4. The load was too light and the rule has been holding — check the rep range is right for the movement.
Between blocks. The natural time.

What the editor will not do

It will not write your programme. It is an editor, not a generator. Writing a periodised block requires your goal, your event date, your history, your schedule and your preferences, and software asserting an eighteen-week plan from four data points is asserting a certainty it does not have.

It will not enforce a template. If you want to run 5/3/1, build it here and the app will run it.

It will not stop you programming too much volume. It will show you the fractional set count per muscle per week, next to your endurance hours, and let you draw the conclusion.

What to do next

The five constraints any workable hybrid week satisfies is the reasoning behind the split choice, and the volume calculator will tell you where your current programme actually sits.