How We Build Your Training Plan (and Why It Looks the Way It Does)

It's Tuesday morning. You open TheNextHill, tap into your plan, and see today's session: a 40-minute Zone 2 run followed by hip and ankle mobility work. Next Tuesday, same slot, it's tempo intervals. Three weeks later, the whole plan shifts again. Shorter sessions, sharper intensity, a deload week you didn't ask for but probably need.

None of this is random. There's an engine behind it, and the decisions it makes are grounded in how endurance coaches have structured training for decades.

The backbone: traditional periodization

Every plan we generate follows a four-phase structure. Foundation first, where volume is moderate and intensity is low. Build phase next, where both ramp up and the hard sessions arrive. Then specificity, where training mirrors the demands of your actual adventure. Finally, taper, where volume drops and your body absorbs the work you've done.

This is traditional periodization, and it has been the dominant model in endurance sport since the 1960s. The reason is simple: it works. Olympic distance runners, professional cyclists, world-class cross-country skiers. The vast majority still organize their seasons this way, building an aerobic base early and sharpening toward race-specific fitness later.

The phases break down roughly as 30% Foundation, 35% Build, 25% Specificity, and 10% Taper. If your plan is 18 weeks long, that's about five weeks of base building, six weeks of progressive overload, five weeks of adventure-specific training, and two weeks of controlled recovery before your event.

Why not something newer?

Block periodization gets a lot of attention. The idea is to concentrate on one physical quality at a time: a pure strength block, then a VO2 max block, then race-specific speed. It can work well in certain contexts, particularly for athletes managing multiple peaks in a season.

But for the person training for a single major adventure over 12 to 24 weeks, traditional periodization solves the right problems. It is predictable. It is easy to understand. And it provides a stable framework that coaches can adjust around the inevitable disruptions of real life: a bad knee, a work trip, a week where sleep falls apart.

A recent paper reviewing periodization across Olympic endurance sports found that traditional periodization still dominates at the elite level, not because coaches are stuck in the past, but because it keeps solving practical problems that flashier models don't address. The best coaches use it as the skeleton and then adapt everything else around the athlete in front of them.

That's exactly what our engine does.

Where it gets personal

The traditional structure is the backbone. The individualisation is the muscle.

When your plan generates, the engine analyses the gap between your current fitness (from your Garmin data or manual scores) and what your target adventure demands across four dimensions: cardiovascular fitness, muscular strength, altitude tolerance, and duration stamina. Your weakest dimension gets the most training slots. Your strongest gets maintenance work. Two people training for the same adventure will get different session mixes because their gaps are different.

Plan length scales to readiness. If you're already 75% ready for a half marathon, you don't need a 24-week plan. You need six focused weeks. If you're at 25% readiness for Kilimanjaro, the engine gives you the full runway.

Sessions adapt to what you actually have. No gym? Bodyweight alternatives. No resistance bands? The prehab sessions adjust. Training for a multi-day trek? You'll see consecutive walking days with a loaded pack in the Specificity phase, because that's what the adventure demands. Training for a century ride? Back-to-back riding days appear in Build and increase in frequency as you approach race day.

Every third week in the Build phase, volume drops 30%. You didn't ask for a deload. You might not feel like you need one. But the research on master athletes is clear: recovery is where adaptation happens, and the 50+ body needs more of it than the 30-year-old body does.

What the phases actually feel like

Foundation is the phase where nothing feels hard enough. You'll wonder if the plan is broken. It's not. You're building the aerobic base and connective tissue resilience that everything else sits on top of. No hard efforts. Two strength sessions a week. Prehab and mobility on easy days.

Build is where things get interesting. Two high-intensity sessions per week appear. Volume climbs. The deload weeks arrive every three weeks, cutting volume but keeping one hard session to maintain sharpness. If you're training for a trek, the intensity looks different: loaded carries and sustained Zone 2 walking rather than VO2 max intervals.

Specificity is the phase that feels most like the adventure itself. If you're preparing for a multi-day trek, you're doing full pack and real boots. If it's a long cycling event, you're practicing nutrition on the bike and riding consecutive days. Volume holds near its peak but doesn't climb further.

Taper is short and aggressive. Volume drops to roughly half of peak. Sessions go from four or five per week down to two or three. You keep one hard session to stay sharp. The rest is recovery. Your fitness is banked. The job now is to arrive fresh.

The honest version

No training plan survives contact with real life. Injuries happen. Work gets busy. Sleep falls apart for a week. The structure matters because it gives you something to return to when things go sideways. Miss a week in Build? You know where you are in the progression and you pick up where you left off. The plan doesn't collapse because you skipped three sessions.

Traditional periodization has survived sixty years of alternative models for a reason. It is simple enough to follow, structured enough to be effective, and flexible enough to absorb the chaos of being a real person with a real schedule and a body that doesn't always cooperate.

We built the engine on that foundation. Your gaps, your gear, your adventure, and your timeline make it yours.