Training for the MO' Cowbell? The injuries that appear as your mileage climbs.

Late summer in St. Charles County has a rhythm to it: the long runs get longer, the weekly mileage creeps up, and the calendar points at a race. For a lot of local runners that race is the MO' Cowbell Marathon & Half in St. Charles — a fall event that pulls training peaks into August and September. That is also, predictably, when the aches start. The pattern is so consistent that we can almost set a clock by it: as the miles climb, the same handful of overuse injuries walk through the door.

None of them are mysterious, and most are catchable early. The trick is knowing which twinges are just your body adapting and which ones are the first quiet warning of something that will end your build if you ignore it.

Why do running injuries show up when marathon mileage climbs?

Almost every training injury we see is a load problem, not a weakness problem. Tendons, bone and connective tissue all adapt to running — but they adapt slowly, and they adapt on their own timeline, not your training plan's. When weekly mileage jumps faster than the tissue can rebuild, the damage outpaces the repair, and what should have been a stronger Achilles or shin becomes an irritated one.

This is the reasoning behind the old “roughly 10% a week” guideline for adding volume. The number is not magic, and plenty of runners bend it, but the principle holds: the injuries below cluster around the exact weeks when someone ramps too hard, comes back from a missed week and tries to make it up, or stacks a long run on top of legs that never recovered from the last one. The Katy Trail is a forgiving surface to log those miles on — flat, soft underfoot — but even a perfect surface will not save a schedule that climbs too fast.

What are the most common injuries as training mileage climbs?

Five come up again and again in the late-summer build. Each has a signature, and each one responds far better when it is caught in the “annoying” stage than the “I had to walk home” stage.

• Achilles pain. Stiff and sore for the first steps out of bed, warms up enough to run, then flares that night. That morning-stiffness signature is the classic tell of Achilles tendinopathy — the tendon has stalled mid-repair and needs the right loading, not just rest. We go deep on it in our Achilles tendinopathy article.
• Heel and arch pain. A sharp, first-step-in-the-morning stab under the heel is plantar fasciitis — often called simply heel pain before anyone knows the term. It loves a sudden jump in mileage or a worn-out shoe. More in the plantar fasciitis guide.
• Runner's knee. A dull ache around or under the kneecap, worse on downhills and stairs and after long sits — what most people just call runner's knee, and what clinicians call patellofemoral pain. The American Academy of Orthopaedic Surgeons ties it to overuse and how the kneecap tracks under load, not to damage in the joint.
• Shin pain. An ache along the inner edge of the shinbone that shows up early in a run — the familiar “shin splints.” AAOS describes shin splints as an overload of the muscle and bone along the shin, common when runners change distance or intensity too quickly. Shin pain that sharpens to one tender point deserves respect — that is the pain that can hide a stress fracture.
• Low back and hip pain. Long runs load the whole chain, and tired glutes hand the work to the low back and the outer hip. When the outer-knee or outer-hip line lights up, it is often the IT band complaining about the volume — see our IT band syndrome breakdown.

When is running pain acceptable and when should you stop?

Not every ache is a red flag. Muscles that are sore in a general, both-legs, day-after way are simply adapting. The rule of thumb we give runners: pain that stays at a low level, does not get worse as the run goes on, and is gone the next morning is usually noise. You can train through that.

The warning signs are the opposite of all three. Pain that climbs during the run, pain that changes your stride, pain sharp enough to point to with one finger, or pain that is worse the next morning than it was during the run — those mean the tissue is losing the repair race, and pushing through digs the hole deeper.

The niggle you catch in week two is a two-week fix. The one you run through until race week is a two-month one. Runners don't get hurt by the mileage — they get hurt by ignoring the first three runs that told them something was wrong.

A quick note on the genuinely serious: pain that wakes you at night, a shin or foot spot so tender you can't bear weight, numbness or pins-and-needles down the leg, or any pain paired with swelling and warmth is not a training question — see a physician before your next run to rule out a stress fracture or other injury.

Do recovery weeks actually matter?

Yes, and they are where the adaptation actually happens. Tissue rebuilds during the easy days, not the hard ones, which is why a build that climbs for three or four weeks and then drops volume by 20–30% for a “down week” produces stronger, more durable runners than one that grinds upward without a break. The down week is not lost fitness — it is when the fitness gets banked.

Sleep, protein and easy cross-training on the Katy Trail or a bike do the same job at the daily scale. Most of the overuse injuries above trace back to a schedule that never gave the tissue a quiet week to catch up.

What good treatment looks like when a niggle won't quit

When two weeks of sensible self-care — a small volume cut, easy days, and loading the sore tissue rather than only resting it — hasn't moved the needle, that is the signal to get assessed rather than to gut it out. The first job is to find the actual driver: a runner's knee that traces to weak hip control, or an Achilles that flares because the calf can't handle the load, won't resolve by treating the sore spot alone.

That is where a rehab-focused approach earns its keep — we pair hands-on care with the specific loading work that rebuilds the tissue's capacity so it holds up to race-week mileage. For stubborn tendon and fascia cases — a lingering Achilles or a heel that won't settle — Shockwave Therapy is offered as a $375 three-session package, the minimum recommended course, to restart repair in tissue that has stalled. The Cleveland Clinic notes most heel-pain cases resolve with conservative care — the goal is to get there without losing the season.

The runners who make it to the start line healthy are rarely the ones who never felt a twinge. They are the ones who treated the early twinge as information, adjusted, and kept the base intact. If something has been nagging for more than a couple of weeks, get it looked at now — a small fix in August protects the race in October. Runners across St. Charles and the wider county see us for exactly this.