Can Hill Work Replace Your Gym Time? I Ran the Study on Myself to Find Out.

Someone asked me recently whether hill running could substitute for gym work. It's a question I hear a lot, and I've always given a nuanced answer — because I think the honest answer is somewhere in the middle.

When I came across this 2025 study, I knew it was the one. Not just because it was new. Because the researchers basically designed their intervention around the exact same question, by swapping out the athletes' strength work with an extra set of hills. That substitution is exactly what people are asking about — and it's the same tradeoff strength training advocates debate every season.

So I did what any curious DPT and ultramarathoner would do. I decided to run the protocol on myself and find out.

The Research

Citation: Alemu Y, Tadesse T, Birhanu Z. The effects of uphill training on the maximal velocity and performance of middle-distance runners: a randomized controlled trial. Scientific Reports. 2025 Jul 2;15:22709.

A randomized controlled trial out of Bahir Dar University in Ethiopia took 40 moderately trained middle-distance runners aged 16 to 20 and split them into four groups for 8 weeks:

• Shallow hill training at 2.5% grade
• Intermediate hill training at 5.1% grade
• Steeper hill training at 7.6% grade
• A control group that kept doing their normal training

The key design detail that made me pick this study: the intervention groups replaced one of their strength training sessions with an additional hill session. Two hill days per week instead of one hill day plus one strength day. That's the exact substitution people are asking me about.

Three things were measured before and after: maximal velocity via a flying 30-meter sprint, 800-meter time trial performance, and strength endurance via a one-minute burpee test.

What They Found

Here's how the 800-meter time trial shook out across groups:

| Group | Start | Finish | vs. Control | |---|---|---|---| | Steeper (7.6%) | 2:11 | 1:53 | 29 sec faster | | Intermediate (5.1%) | 2:07 | — | 25 sec faster | | Shallow (2.5%) | 2:07 | 2:01 | No significant difference | | Control | 2:11 | 2:12 | — |

Note: The intermediate group's absolute finish time contains what appears to be a reporting inconsistency in the published paper, so I'm reporting their improvement over control rather than a specific finish time.

A few other things that stood out:

• The steeper group improved max velocity by 0.93 m/s over the control group — without sprint training being the intervention. The control group's max velocity didn't move at all (7.17 m/s before and after). The steeper group went from 7.46 to 8.74 m/s.
• The intermediate group improved their 800m but didn't produce significant gains in max velocity or strength endurance on their own.
• The shallow group produced zero significant improvements over the control group in any outcome. None.
• Two sessions per week was the dose — not daily hill work.

What This Means For Your Training

The performance findings are real and meaningful. An 18-second improvement in the 800m for the steep group is significant. But seeing max velocity gains without sprint training as the intervention — just the hills — is what genuinely caught my attention as a coach.

I train max velocity with my high school cross country and track athletes every other week. We do flying sprints and measure 30-meter flies, the exact same test this study used. I've seen what dedicated sprint work does for those times. Seeing hills move that needle without being the primary focus tells me there's something worth paying attention to here.

The strength finding needs some honesty

Here's where I want to pump the brakes a little. The study measured strength endurance with a one-minute burpee test. Burpees are a valid test of general fitness. But from a PT standpoint, a burpee tells me very little about whether your calves can handle 10,000 foot strikes per hour or whether your glutes are producing force efficiently at mile 18.

I would have much rather seen a calf raise test, a single leg squat, or a step-up — something specific to what distance running actually demands. The strength improvement is interesting. I'd just hold it loosely.

My honest take after reading the full paper: hills can probably cover some of what the gym does. Your calf loading, lower body endurance, some neuromuscular work — I think you're getting that from steep, hard hill efforts. Your heavy deadlifts and loaded squats? I don't think the hills are replacing those.

The Goldilocks answer here: if you genuinely won't do two to three strength days per week, one hard strength day plus one hill day looks like a reasonable real-world compromise based on this evidence.

My Baseline Numbers — I'm Running the Protocol

I'm not just summarizing this one and moving on. I'm running the 8-week protocol on myself and retesting all three measures at the end.

Here are my baselines:

For context: the steeper group in this study averaged 7.46 m/s and 20.3 burpees at baseline. I'm sitting right there with them. They finished at 8.74 m/s and 25.8 burpees.

My 800m splits tell a story too. My last 200 being my fastest means I was conservative out of the gate. There's time in there. I'm doubtful I'll improve as much as a group of 16 to 20 year olds — being 34 and coming off ultra training is a different physiological starting point — but I'm genuinely curious what 8 weeks of this produces.

I'll update with my results at the end of the protocol.

The Full 8-Week Protocol

Two sessions per week, added on top of your normal easy running. All efforts at 85 to 100% of max heart rate. Rest fully between reps — this only works if the efforts are actually hard.

One honest warning: these sessions take a while. The rest periods are long by design. Budget the time accordingly before you commit.

Steeper group — 7.5% grade (the group that improved everything)

2 to 4 minutes rest between reps. 4 to 6 minutes rest between sets.

| Week | Protocol | |---|---| | Week 1 | 4 sets × 6 reps × 30 sec | | Week 2 | 4 sets × 8 reps × 30 sec | | Week 3 | 4 sets × 10 reps × 30 sec | | Week 4 | 4 sets × 6 reps × 45 sec | | Week 5 | 4 sets × 8 reps × 45 sec | | Week 6 | 3 sets × 10 reps × 60 sec | | Week 7 | 3 sets × 6 reps × 90 sec | | Week 8 | 3 sets × 7 reps × 90 sec |

Intermediate group — 5.1% grade (the group that improved their 800m)

2 to 4 minutes rest between reps. 4 to 6 minutes rest between sets.

| Week | Protocol | |---|---| | Week 1 | 2 sets × 6 reps × 60 sec | | Week 2 | 2 sets × 8 reps × 60 sec | | Week 3 | 2 sets × 10 reps × 60 sec | | Week 4 | 2 sets × 6 reps × 90 sec | | Week 5 | 2 sets × 8 reps × 90 sec | | Week 6 | 2 sets × 10 reps × 90 sec | | Week 7 | 2 sets × 6 reps × 2 min | | Week 8 | 2 sets × 8 reps × 2 min |

How To Implement It

Find a hill with real pitch. 5 to 8% grade minimum. A gentle road roller won't cut it. If you're on a treadmill, set the incline deliberately — that's what I'm doing, set to 7.5%.

Two dedicated sessions per week. Added to your normal training. This is not a daily thing.

Keep the efforts hard. 30 to 90 seconds at near-maximal effort with full rest between reps. A casual jog uphill is not the same stimulus. The gradient is the tool, but the intensity still has to be there.

Commit to 8 weeks minimum. Neuromuscular adaptations don't show up in two weeks. Don't judge this after one session or even one month.

Don't drop your heavy strength work entirely. One hard strength day plus one hill day is the reasonable real-world compromise this evidence points toward. Calf raises, deadlifts, and squats are still doing things hills can't fully replicate.

A Note on the Study's Limitations

I want to be transparent about something. Some of the reported 800m times in this paper contain what looks like a data reporting inconsistency — particularly for the intermediate group's finish times. It's the kind of thing you only catch if you read the full paper carefully rather than just the abstract.

This doesn't invalidate the findings. The statistical analysis is sound and the directional results hold up. But it's a good reminder that a study's conclusions are a guide, not a precise prescription — especially with sample sizes of 10 per group. Use this as a directional signal, not a promise of specific time improvements.

The Bottom Line

Not all hills are created equal. A 2.5% grade — which is basically what you run over without thinking about it on a rolling road — produced nothing measurable in this study. The 5 to 8% range is where adaptation appears to happen.

Can hills fully replace your gym work? Based on this evidence: probably not. Can they cover some of it, and serve as a meaningful supplement or partial substitute for runners who won't do three strength days per week? This study suggests yes.

I'm 8 weeks away from my own answer. I'll share the retest numbers when I have them.

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