Estimated read time: 5.5 minutes (about as long as it takes me to accept I’m out of gels the night before my long run 😬)

Hey Performance Nerds! Jonah here. 🤓

Running loads your bones, but it may not give them every signal they need.

A big mistake runners make is thinking lifting is only for muscles. You should be using the gym to train muscle and bone.

Here's what you'll learn today:

(Augie's bone plan? Sprint at squirrels, jump on the couch, then recover all afternoon.)

The gel I race with and keep recommending because the formula makes sense: BETA FUEL delivers 40g of carbs per gel through a 1:0.8 maltodextrin-to-fructose ratio.

That ratio is the point. It helps you use multiple carb transporters, push higher intake, and keep the gut calmer when fueling gets serious.

Stryd gives runners power, pacing, and mechanical metrics that can make training decisions clearer when pace and heart rate do not tell the whole story.

See this week's full Stryd training tip at the end of this newsletter.

Running counts as bone loading. Every landing sends a real signal through the bones taking that load.

Fredericson et al. (2007) compared small groups of elite male runners, soccer players, and controls.

Runners had denser heel bones than controls. Soccer players had denser hips and spines than runners.

The study captured only one moment, so it can't show either sport caused those differences.

The likely difference? Soccer adds more speed and direction changes.

When you lift, your muscles contract hard and pull on bone through their tendons. Jumps add another burst of force when you land.

Both forces slightly bend the bone. That tiny change in shape is called bone strain.

Bone cells sense that strain and respond. Over time, they can add or rebuild tissue where the load is highest.

Running creates this signal too. But heavier lifts and jumps can create a larger, faster, or less familiar strain signal.

Over time, that bigger signal may help build denser bone. That may give runners more capacity to handle repeated loading.

Running loads bone, but your usual stride may leave gaps.

Bone moves slower because it repairs tiny sections at a time.

First, your body removes a tiny section of old bone. Then it slowly refills that space.

Eriksen (2010) reported about 120 days for dense outer bone.

Cancellous bone, the spongier tissue inside bones, took about 200 days.

Think of road crews repairing blocks across a city. They aren't repaving every road overnight.

Your bones work the same way. One tiny section can take roughly four to seven months.

Muscle strength may improve before a bone-density scan can measure a change.

Give your strength and jump routine at least six months before looking for a measurable change.

Eight to twelve months gives the plan a fairer test.

Runners often hear two bad options: lift tiny weights forever or chase maximal barbells.

Make the set hard, not the load maximal.

A review compared exercise intensities across adults over 50 (Kast et al., 2022).

Some results favored harder training.

Moderate-to-heavy lifts create more force as your muscles pull on bone. Plyometrics add quick bursts of force when you land.

The current best bet is challenging lifting with moderate-to-heavy loads, plus plyometrics.

For your main lifts, aim for about 4 to 12 challenging weight reps. Finish with two or three clean reps left.

When that gets easy, add weight or make the exercise harder.

Easy sets of 20 to 30 reps with very light weights can still train muscle. But they are probably a weaker bone-building bet than heavier sets where you gradually add weight.

Thirty-eight active men with low bone mass completed the trial (Hinton et al., 2015).

Twenty of 58 starters didn't finish.

Both groups also received calcium and vitamin D.

Resistance training happened twice weekly. Jump training happened three times weekly.

Across the two groups, whole-body and spine density rose after six months.

Hip density rose only in the resistance-training group.

Healthy runners shouldn't copy this program line for line. The useful part is the combination and timeline.

Keep running. Bone seems to respond well to brief bursts of high force.

Repeated, familiar loading may add less new stimulus.

Think progressive squats, deadlifts, lunges, calf raises, hops, and low-volume jumps.

Two strength sessions are a reasonable starting point. We still don't know the best frequency.

Build strength and force tolerance before progressing impact. Advanced jumps aren't required to start.

Ask a doctor before hard impacts or very heavy lifting if any item below applies.

Bottom line: Plan your bone work in six-month blocks, not six-week fixes.

Jonah

Welcome to the prove you're a nerd section. Each week, I ask a question about a common running science myth. Answer correctly, and you'll be entered into a weekly raffle to win a package of Jonah's favorite supplements.

Last week's poll asked: "Two runners have the same VO2 max. Why might the runner with more slow-twitch muscle fibers be better suited to the marathon?"

Most of you got it. Marathon performance is not only about the size of the engine. It is also about how efficiently your muscles can repeat the work for hours.

The correct answer?

C. Slow-twitch fibers rely heavily on aerobic energy and resist fatigue, which suits hours of repeated submaximal contractions

Slow-twitch fibers are built for repeated aerobic work. They produce less peak force than fast-twitch fibers, but they resist fatigue and keep producing submaximal force efficiently.

That helps explain why two runners with the same VO2 max can still be very different marathoners.

Here's how the votes shook out:

A. Slow-twitch fibers produce more peak force, so fewer fibers are needed to hold marathon pace: 8 votes, about 3 percent
B. Slow-twitch fibers store substantially more glycogen, delaying the need for race fueling: 9 votes, about 4 percent
C. Slow-twitch fibers rely heavily on aerobic energy and resist fatigue, which suits hours of repeated submaximal contractions: 199 votes, about 85 percent
D. Slow-twitch fibers are recruited after fast-twitch fibers fatigue, creating a late-race reserve: 17 votes, about 7 percent

Total votes: 233

Why D was tempting:

Fatigue can force your body to recruit more fast-twitch fibers later in a race. But slow-twitch fibers are not the late reserve. They do most of the steady work from the start.

Bottom line?

VO2 max helps set the ceiling. Your muscle traits help determine how efficiently you can use it for 26.2 miles.

I ran eight controlled hill accelerations on one familiar climb. Each rep built to 100% effort, with two minutes for full recovery.

I use hill work to train neuromuscular power. Quantifying each rep is difficult.

Short hill reps often end before GPS pace stabilizes. Pace alone doesn't show the extra effort cost of climbing.

That is why I track Stryd Power. I average Power across all eight work reps.

I keep the hill, reps, and recovery identical. My session average started around 875 watts.

Months later, it reached roughly 925 watts. That 50-watt rise is a practical sign my short-duration power improved.

That stronger output is exactly what I want from this session.

Same hill, same workout, stronger output.

Why it matters:

Try this: choose one hill and run eight controlled accelerations to 100% effort. Recover two minutes between reps.

I repeat this exact session a few times throughout my training block.

Try it on your next run