You already know strength training improves how efficiently you run. We covered that in Issue 001. The research on that is clear and consistent. But here is the question nobody was asking until recently: does strength training keep your efficiency from falling apart when you get tired? Because that is when it matters most. Not mile one. Mile eighteen. The back nine of your ultra. The final kilometer when the race actually gets decided. A 2025 randomized controlled trial published in Medicine and Science in Sports and Exercise set out to answer exactly that question. And the finding that stood out most was not the running economy result. It was a 35% improvement in what happens when runners are already exhausted.
ARTICLE BELOW:
The Research
Researchers took 28 well-trained male runners with an average 10k time of around 39 minutes and split them into two groups for 10 weeks. One group continued their normal running training. The other added two strength sessions per week on top of their running. The strength group was not told to change their running. Both groups just kept doing what they were doing, with the strength group adding the gym work on top.
They measured two things. First, running economy at every 15-minute checkpoint across a full 90-minute run at marathon-effort intensity, somewhere between aerobic and anaerobic threshold. Second, a time to exhaustion test at 95% of VO2max done immediately after that 90-minute run, simulating the final kick of a race when you are already deeply fatigued.
What They Found
The research suggests these are the key takeaways
🟢 Strong evidence — well-designed RCT with performance-matched groups and a novel, race-relevant outcome. Main caveat: well-trained men only, averaging a 39-minute 10k. The findings are consistent with the broader strength training literature, which adds confidence.
The strength training group maintained their running economy better across the 90-minute run. As fatigue set in, their efficiency held up. The running-only group showed more degradation as time went on.
The more striking finding was in the time to exhaustion test. After 90 minutes of running, the strength group could sustain high-intensity effort 35% longer than before the 10-week program. The running-only control group did not see any improvement.
Think about what that means in practice. The test was done at 95% of VO2max, a very hard effort, after 90 minutes of running near marathon effort had already accumulated. The strength group lasted significantly longer at that intensity. Their legs had more left.
What This Means For Your Training
This is the third piece of a story we have been building without fully naming it.
Issue 001 showed that strength training makes you more efficient when fresh. Last week's fueling issue showed that carbohydrate intake improves time to exhaustion and protects performance late in long efforts. Now this study shows that strength training specifically protects the back half of your run, it keeps your economy from degrading and improves what you can do when you are already tired.
All three of those are about the same problem. You start the race fine. The question is what happens at the end.
I think we can apply this beyond the marathon context the study was designed for. For half marathons and marathons, the durability finding is very direct, holding your economy together for 90 minutes at threshold effort is exactly what those races demand. For ultramarathons, the carryover is a little more nuanced because ultras are not run at 95% VO2max. But being more efficient throughout, and having more reserve when you need to push, is still valuable at any distance. The mechanism transfers even if the specific intensity does not.
The Protocol They Used
Here is exactly what the strength group did. Two sessions per week, approximately 45 minutes each, progressing over 10 weeks.
Exercise | Week 1-3 | Week 4-7 | Week 8-10 |
|---|---|---|---|
Vertical plyometrics | Pogo jumps — 3 x 10-12 / 90s rest | Drop jumps — 3 x 6 / 120s rest | Drop jumps — 3 x 6 / 120s rest |
Horizontal plyometrics | Hop and stick — 3 x 6 / 90s rest | Stiff leg bounds — 3 x 10 / 90s rest | Bounds for length — 3 x 8-12 / 90s rest |
Back squat | 3 x 6-8 / 120s rest at 65-80% 1RM | 3 x 5-6 / 120-150s rest at 80-85% 1RM | 3 x 4-5 / 150s rest at 85-90% 1RM |
Single leg press | 3 x 6-8 / 120s rest at 65-80% 1RM | 3 x 5-6 / 120-150s rest at 80-85% 1RM | 3 x 4-5 / 150s rest at 85-90% 1RM |
Seated isometric calf raises | 4 x 6-8 / 60s rest at 80-100% MVF | 5 x 4-6 / 90s rest at 100% MVF | 5 x 4-6 / 90s rest at 100% MVF |
A few things worth noting about this protocol. The load progresses meaningfully across the 10 weeks, starting at 65 to 80% of 1RM and building to 85 to 90% by weeks 8 to 10. That is heavy. The plyometrics also progress in demand, from pogo jumps and hop-and-stick in the early weeks to drop jumps and bounds for distance later. This is the same combination principle we covered in Issue 001 and the same structure built into Phase 4 of the 12-Week Runner Strength Foundation Program (see below) heavy load plus plyometrics, progressed deliberately over time.
The seated isometric calf raises are an interesting detail. Isometric at 80 to 100% of maximal voluntary force. This is not a gentle calf raise. This is the calf being loaded at maximum effort, held under tension. It is a direct nod to the soleus loading we talked about in Issue 002.
🏆 How To Apply It
Two strength sessions per week on top of your normal running. Not instead of running. On top of it.
Start with a manageable load in the first three weeks, the 65 to 80% of your 1RM range. Your goal is to establish the movement patterns and build a baseline before adding the heavier loads in weeks four through seven and again in weeks eight through ten.
If you do not have a barbell for back squats, a heavy goblet squat or a loaded split squat covers the same stimulus. Single leg press can be replicated with a Bulgarian split squat or a weighted step-up. The specific equipment matters less than the load and the progressive overload over time.
Give it 10 weeks before judging results. The study ran 10 weeks for a reason. These adaptations take time.
And if you are looking for a structured program that follows this exact protocol logic, two-three sessions per week, plyometrics plus heavy strength, progressive overload built in across 12 weeks, that is exactly what the 12-Week Runner Strength Foundation Program is designed to do.
The back half of your race is where everything you have built either holds or falls apart. The research is getting clearer on what helps it hold.
Hit reply and tell me: do you notice your form or pace falling apart in the final miles of your longer efforts? I read every reply and the answers genuinely shape what I cover next.
-Keep running happy, healthy, and strong
Spencer
One more thing before you go.
The 12-Week Runner Strength Foundation Program builds this exact protocol logic into a structured 12-week plan, heavy load, plyometrics, progressive overload across four phases. (starts body weight and light for you folks that are new to strength training) Built from the research. Three days a week. $27.
Stronger Stride is brand new and I'm building this from the ground up. If you know a runner who would get value from evidence-based training content broken down in plain language. Maybe a training partner, a running club friend, someone who's always asking about strength work, I'd be really grateful if you shared it with them.
Just forward this email or send them your personal referral link below from the button below (hopefully it works haha), or send them HERE. As the newsletter grows I'll be setting up rewards for people who help spread the word. Think bonus research deep-dives, free guides, and more. But honestly right now the biggest reward is just knowing this is reaching runners who need it.
Thank you for being here from the very beginning. It means more than you know.