Last week we talked about what type of strength training actually moves the needle for runners. Heavy load and plyometrics won. Light circuit work with kettlebells did not. But that leaves a bigger question: which muscles should you actually be loading? Most runners I talk to are doing squats, deadlifts, lunges, split squats. Great compound movements. Lots of muscle groups under load. That's exactly what we want. But there's one muscle group that quietly does more work at the paces you actually run than almost anything else, and most people are either skipping it or training it wrong.
The Research
A 2012 study out of the University of Melbourne combined gait analysis with a detailed computer model of the leg's musculoskeletal system to figure out which muscles produce force at different running speeds. Nine experienced runners ran at four speeds, from a 7:40 mile pace all the way up to sprinting. The researchers calculated exactly how much force each muscle produced at each pace, and how each one contributed to pushing the body off the ground.
What They Found
The research suggests these are the key takeaways
🟡 Moderate evidence — well-designed biomechanical modeling study but small sample size (9 runners) and not a training intervention. These are mechanistic patterns, not direct training prescriptions.
Running speed comes from two things: how long your stride is, and how fast you cycle your legs. The equation is simple. Speed equals stride length times stride frequency.
Up to about a 3:50 mile pace, runners get faster mostly by lengthening their stride. That requires pushing harder against the ground.
The calf complex, especially the soleus, is the dominant force producer at those paces. At a 7:40 mile pace, the soleus alone produced peak forces of nearly 8 times body weight during ground contact. The gastrocnemius added another 2.7 times body weight on top.
Above roughly a 3:50 mile pace, the calves max out and the hip muscles take over. Glutes and hamstrings roughly doubled their peak force between the 3:50 and 3:00 pace.
The quadriceps barely changed across all four speeds. The big muscle most lifting programs prioritize is not the one driving your training pace.
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
Most people, when I talk to them about what they're doing in the gym, are doing squats or deadlifts or lunges or other compound movements. That's awesome. They target a wide variety of muscle groups, and they're trying to do them under load, which again is what we're looking for. The one thing that's often missing is heavy calf raises.
Here's where it gets interesting. Most runners who do calf raises got the prescription from Google after typing in "Achilles pain." They have the two-feet-up, one-foot-down off the edge of a step variation. And they think that's enough load. In actuality, it's not. That's a rehab exercise, not a strength exercise. You need to progressively load the calves heavy, the same way you load every other muscle group.
The other piece most people miss is that the calf complex is two muscles. The gastrocnemius is the one most people picture, the upper calf. The soleus sits deeper underneath. Here's the key: the gastrocnemius crosses the knee, so straight-leg calf raises target it. The soleus does not cross the knee, so to isolate it you need to do calf raises with a bent knee. The seated calf raise machine at the gym is perfect for this. If you don't have one, I've done this at home with a heavy weight on my lap. Kids work. So does the dog.
🏆 How To Apply It
Add dedicated heavy calf work 2 to 3 times per week. Treat it with the same intent as your squats and deadlifts. Progressive overload, not bodyweight forever.
Train both calf muscles separately. Standing calf raises for the gastrocnemius. Seated or bent-knee calf raises for the soleus.
Aim for 3 sets of 6 to 12 reps with a weight that genuinely challenges you by the last few reps. If you can do 25 bodyweight reps without breathing hard, that's not strength work.
Don't drop the compound lifts. The hips and glutes still drive your faster paces, your hill work, and your race finishes. Keep deadlifting and squatting.
If you don't have gym access, get creative with load. A loaded backpack, weight on your lap during bent-knee raises, your kid sitting on your shoulders for standing raises. The principle is the same: enough resistance to push the muscle to genuine fatigue.
The takeaway from this study is mechanical, not magical. Your calves are doing the most work at the paces you actually run. If you've been treating them like an afterthought or doing the same bodyweight raises you got prescribed for Achilles pain three years ago, you're leaving a real chunk of performance on the table. Especially as you age.
Hit reply and tell me what your current calf work looks like, or if you don't do any at all. I read every reply, and I'd love to know what's actually happening in your gym routine.
-Keep running happy, healthy, and strong
Spencer
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