Efficiency vs Strength in Ultra-Running: Why the Difference Exists (and How to Train for Each)

Not all ultra-marathons stress the body in the same way. Some races reward smooth, efficient running where you lock into a rhythm and hold it. Others demand strength, resilience, and the ability to absorb hours of climbing, descending, and challenging terrain.

Plus a few races throw it all at you at once, usually somewhere around hour 12 when you least expect it. We’re thinking of you West Highland Way, with your combo of military roads and loch side obstacle course!

Understanding whether you or your event are efficiency-based or strength-based is one of the biggest upgrades you can make to your training.

Get it right, and your sessions match the demands of your race. Get it wrong, and you end up fit in the wrong areas, like turning up to a hill race with road legs, or trying to pace a flat 100 like you’re in Chamonix.

So let’s break down why this difference exists, how it affects performance, and how to train for each style of course.

Why the Difference Exists

1. Mechanical repetition vs mechanical variability

Runnable ultras, canal paths, flat 100s, park loops, road 50Ks, involve repeating the same movement pattern thousands of times. You settle into a rhythm and hold it. The biggest limiter becomes running economy: how efficiently you move, how much fuel you burn per mile, and whether your form holds up.

Hilly or technical courses are the opposite. Every climb, descent, bend, mud patch, and root forces a change in mechanics. You recruit different muscles, shift posture, brace, stabilise, and load tissues eccentrically. The limiter might not be economy, it could be muscular resilience.

In short:

• Flat/runnable races: repetition demands efficiency
• Hilly/technical races: variability demands strength

2. Different stress pathways

Runnable races lean heavily on:

• aerobic metabolism
• smooth cadence
• elastic return
• steady fuelling
• consistent pacing

They’re physiological challenges.

Hilly races lean heavily on:

• muscular strength
• eccentric control
• climbing power
• impact tolerance
• local fatigue resistance

They’re mechanical challenges.

It’s not that one is harder than the other, they’re just hard in different ways.

3. Different “failure points”

What slows you down first?

On runnable courses: Form breaks down. Cadence drops. Stride shortens. Efficiency disappears and effort creeps up. You can feel perfectly “strong” but still slow dramatically if economy falls apart.

On hilly courses: Local muscle fatigue arrives first. Quads fail on descents. Calves and hip flexors fatigue on climbs. Even if the engine feels fine, the legs say no.

Understanding your failure point tells you what to train.

How to Train for Efficiency-Based Ultras

Think of our events like Thames Path 100, Autumn 100 (flatter legs), canal races, runnable 50Ks/50 milers, road ultras, or any course where you can run almost the whole thing.

1. Prioritise continuous running at steady efforts

Runnable ultras reward rhythm, the ability to find a smooth, efficient stride and hold it for hours without drifting into fatigue.

To build that, you need regular sessions where you simply run continuously at a comfortable or steady pace. Long aerobic efforts teach your body to spare glycogen, refine movement patterns, and become economical at a sustainable speed.

Controlled tempo blocks and progression runs help you lock into a pace that feels “comfortably purposeful,” which is exactly the feeling you want on race day. You’re training your body to hum along efficiently, not surge and collapse.

2. Develop pace awareness

You don’t need to obsess over hitting exact splits, but you do want to know how pacing feels across different effort levels.

On runnable courses, pacing errors show up early and compound over time, go 10-15 seconds per mile too fast in the first 30 miles, and you’ll spend the next 20 miles paying for it.

Pace awareness comes from learning what “all day pace” actually feels like on flat ground, what your sustainable cruising speed is, and what happens when terrain shifts slightly. Even simple tools like checking your watch occasionally, using breath as a guide, or practising even splits during medium-long runs can dramatically improve pacing on race day.

3. Build higher running volume (sensibly)

Mileage strengthens the specific tissues used in repetitive running: calves, Achilles, quads, hip flexors, and all the stabilisers around them.

When you run more frequently or at slightly higher weekly volume, your movement pattern becomes more refined, your neuromuscular system becomes smoother, and your efficiency improves. But “more mileage” doesn’t mean reckless jumps, it means gradually raising the number of repeatable running hours so your stride becomes second nature.

Consistency is the secret sauce. Higher mileage develops the sturdy aerobic foundation that runnable ultras demand.

4. Strength supports, but doesn’t dominate

For efficiency-based ultras, strength training is about maintaining form, not overpowering steep climbs. You want glutes that fire reliably, calves that can cope with thousands of repeat footstrikes, and hamstrings that don’t tighten or cramp late into a long flat run.

A simple routine built around calf raises, step-ups, single-leg work, and basic core stabilisation can make a huge difference.

This isn’t mountain leg training, it’s keeping your chassis stable so your efficient stride stays efficient through the back half of a long, flat race.

How to Train for Strength-Based Ultras

Think TransGranCanaria, Madeira Island Ultra Trail, Grand Raid Pyrenees, big mountain races, or anything with relentless climbing, challenging trail, or constant variance.

1. Make hills a training stimulus, not an accident of the route

If your race is defined by climbs and descents, you need structured hill work, not just “running hilly routes.”

That means sessions designed to build climbing strength (long uphill efforts, power-hiking reps), sessions designed to refine descending technique (controlled downhill repeats), and long runs on terrain that actually resembles your race.

Hills shouldn’t appear as background noise; they should be the main feature. You’re teaching your body to recruit glutes, hamstrings, and quads effectively, and to transition smoothly between climbing, descending, and running on the flats.

2. Build eccentric resilience

Downhill running is an eccentric-load festival, the quads lengthen under force repeatedly, which is what causes that deep, lingering soreness if you’re unprepared.

To handle long descents, you need specific work that conditions the tissues for eccentric stress. That could be downhill intervals run smoothly with controlled foot placement, gym-based eccentric quad work (like slow step-downs or split squats), and hamstring-focused exercises such as RDLs or Nordic variations.

The goal isn’t to turn every descent into a sprint. It’s to ensure you can descend efficiently without shredding your quads two-thirds into the race.

3. Strength training becomes non-negotiable

For mountain or hilly ultras, strength training isn’t an add-on, it’s a cornerstone. Heavy-ish strength work increases force production, joint stability, and fatigue resistance, all of which are crucial for climbing and descending long after your form would otherwise break down.

Think big, simple movements: RDLs for posterior-chain resilience, split squats and lunges for single-leg control, step-ups for climbing strength, and core work to stabilise posture when fatigue sets in.

Stronger legs don’t just help you go uphill faster, they protect you downhill and reduce injury risk across the entire race.

How to Choose Your Training Focus

The simplest rule:

If pace, rhythm, and smoothness decide the race: Train for efficiency.If climbs, descents, and muscle durability decide the race: Train for strength.

Most UK races sit somewhere in the middle, and most athletes benefit from a blend. But knowing which side your goal event leans toward helps you optimise training, avoid wasted effort, and stay healthy through the build.

Ultra-running isn’t one sport, it’s several.

Some races reward metronomic rhythm and silky efficiency. Others reward strong legs, resilience, and the ability to cope with endless terrain changes.

A coach can help you figure out exactly what your race demands, ideally before you find yourself staring up at a climb that definitely wasn’t in the race description.

Once you understand which kind of race you’re preparing for, you can shape your training to match the demands, not just follow a generic plan.

Train the system your race will stress. Work on the skills your course profile will require.