A few weeks ago, someone asked me 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 study, I knew it was the one. Not just because it was published in 2025. 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
The Research
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 at 5.1%, steeper at 7.6%, or 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 substitution is exactly what the question asks.
What They Found
The research suggests these are the key takeaways
🟡 Moderate evidence: well-designed RCT with proper randomization and blinded assessors, but only 10 athletes per group (small sample), young population, testing the 800m (how many of you are training for this right now? haha very few I’d guess) and training was done on a treadmill. Directionally strong, not perfect prescriptive.
The steeper group (7.6%) improved in every single outcome: 800m time trial improved significantly (2:11 —> 1:53) over control, max velocity improved by 0.93 m/s over control, and strength endurance improved meaningfully.
The intermediate group (5.1%) improved their 800m time over control but didn't produce significant gains in max velocity or strength endurance on their own.
The shallow group (2.5%) produced zero significant improvements over the control group. None.
The control group's max velocity didn't budge — 7.17 m/s before and after. The steeper group went from 7.46 to 8.74 m/s.
The research suggests the calf complex is doing the majority of the heavy lifting at every pace most of us train at. And within the calf complex, the soleus, the deeper muscle, carries more of the load than the visible upper calf.
What This Means For Your Training
Here's where I have to be honest about what this study does and doesn't tell us.
The performance findings are real and they're meaningful. A 18 second improvement in the 800m for the steep group is unreal to see. Seeing max velocity gains without sprint training as the intervention, just the hills, is genuinely interesting to me as a coach. I train max velocity with my cross country and track kids every other week. We do flying sprints and measure thirty 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.
But the strength finding? I'm going to pump the brakes a little. They measured strength endurance with a one-minute burpee test. I'm not trying to dismiss the study, 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, a step-up, or something specific to what distance running actually demands. The strength improvement is interesting, but I'd 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.
🏆 How To Apply It
I'm not just going to summarize this one and move on. I'm running the protocol on myself.
I already completed my 800m time trial baseline
2:16, running solo in trainers. My splits were 34, 36, 34, 32. My last 200 meters being my fastest tells me I was conservative out of the gate. There's time in there. This weekend I ran my other two baseline tests: max velocity came in at 7.69 m/s on the flying 30. Strength endurance was 21 burpees per minute.
For context: the steeper group in this study started at an average of 7.46 m/s and 20.3 burpees. I'm right there with them at baseline. They finished at 8.74 m/s and 25.8 burpees. I'll be honest, I’m doubtful I’ll improve as much as they did (16-20 y/o vs a 34 y/o), but I'm curious.
Over the next 8 weeks I'm running the steeper protocol: two hill sessions per week on top of my normal easy running, at 7 to 8% grade, short hard efforts at 85 to 100% of max heart rate, with full recovery between reps. Then I retest all three.
ONE BIG CHALLENGE WITH THIS PROTOCOL IS THAT THE SESSIONS TAKE A LONG TIME HAHA, SO BE READY IF YOU’RE GOING TO TRY IT WITH ME.
Here’s the protocol for the steeper group @ ~7.5% (2’ between reps and 4’ between sets):
Week 1 - 4 × 6 × 30s
Week 2 - 4 × 8 × 30s
Week 3 - 4 × 10 × 30s
Week 4 - 4 × 6 × 45s
Week 5 - 4 × 8 × 45s
Week 6 - 3 × 10 × 60s
Week 7 - 3 × 6 × 90s
Week 8 - 3 × 7 × 90s
Here's how to implement it if you want to try it too:
Find a hill with real pitch, 5 to 8% grade minimum. A gentle road roller won't do it. Even better, and what I’ll do is use my treadmill, set the incline deliberately (7.5%).
Two dedicated sessions per week, added to your normal training. This is not a daily thing.
Keep efforts short and hard, 30 to 90 seconds at near-maximal effort, with 2 to 4 minutes of full rest between reps. A casual jog uphill is not the same stimulus.
Commit to at least 8 weeks before you judge results. Neuromuscular adaptations don't show up in two weeks.
Long term, I’d say: don't drop your heavy strength work entirely. One hard strength day plus one hill day is a reasonable real-world compromise based on this evidence. Two to three strength days plus nothing else isn't what was tested here either.
Also, just to be aware some of the results in this study are confusing. I’d love to be able to sit down and ask some questions especially regarding the 800m times. Some of the times are unrealistic if you take them at face value, so I’d love to learn a bit more about what the raw data looked like. Let’s not use this study to give us specific values of times and improvement, but more of a directional improvement. It is a guide…
I'll report back on my own numbers as the weeks go on. If my max velocity and 800m move the way the study suggests they should, that's a story worth telling. If they don't, that's also worth telling.
Hit reply and let me know: what does your current hill work actually look like? Casual rolling terrain, dedicated workouts, or nothing at all? I read every reply.
-Keep running happy, healthy, and strong
Spencer
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