Runner's Plantar Fasciitis: Causes and Solutions

You might know this scenario: your alarm goes off, you put your foot down, and bam — a sharp pain under your heel, like stepping on a pebble. It lasts a few steps, fades, and you forget about it. Until your next run, when it returns. Welcome to the world of plantar fasciitis. I've read quite a bit on the topic because it's an injury that affects so many runners around me, and I wanted to understand what's really going on.

I'm not a doctor or a physical therapist — just a runner who reads up on things. Please take this article for what it is: a sharing of information and personal insights, not medical advice.

What Exactly Is Plantar Fasciitis?

Essentially, under your foot, there's a thick, elastic-like band — the plantar fascia — that connects your heel bone to the base of your toes. This band gives your arch its shape and absorbs shock when you run. With every stride, it supports 2 to 3 times your body weight. In other words, it works hard.

Plantar fasciitis occurs when this band has been overloaded. The word « fasciitis » suggests inflammation, but from what I've read, it's more accurately described as tissue degeneration — specialists often refer to it as « degenerative changes. » Essentially, the fascia breaks down faster than it can repair itself. This is an important detail because it means that classic anti-inflammatory medications won't necessarily solve the root problem.

Risk Factors for Runners

When I've talked to runners who've experienced it, the scenario often comes back to the same things: increasing mileage too quickly, an overly ambitious marathon training plan, or a poorly managed shoe change. Digging deeper, here's what most frequently stands out:

• Too much mileage, too fast — this is a classic. The fascia adapts very slowly, much slower than muscles. If you double your miles in a month, your legs might keep up, but your fascia will pay the price
• Weight — logical when you think about it: the heavier you are, the more impact your fascia absorbs with each step. A high BMI is clearly a risk factor. Our weight impact calculator can help you estimate the concrete effect of a few extra or fewer pounds
• Tight calves — I was surprised to see how often this factor comes up in everything I've read. If your ankle doesn't bend enough (we're talking about dorsiflexion), the fascia compensates and takes a beating. Personally, I think this is the most underestimated factor
• Switching to minimalist or low-drop shoes — if you go from well-cushioned shoes to minimalist footwear overnight, your fascia and Achilles tendon will take on a load they're not accustomed to
• Weak foot intrinsic muscles — we never think about them, but there are many small muscles in the foot that support the arch. If they're weak, the fascia ends up doing all the work
• Standing-intensive job — if you're on your feet all day and then run in the evening, your feet never get a break

What's a bit frustrating is that two runners following the exact same training plan can have completely different outcomes. A light runner with flexible calves might have almost no risk, while a sturdier runner with tight calves could end up with plantar fasciitis on the same training plan.

Clinical Diagnosis First and Foremost

Honestly, if you have these symptoms, it's pretty recognizable:

• Pain under the heel, well-localized
• Worst pain is in the morning with the first few steps, or when you get up after sitting for a long time
• It lessens during warm-up, then returns after your run
• If you press hard under the heel (inner side), it hurts

Generally, X-rays or MRIs aren't needed — a doctor or physical therapist can diagnose it with an examination. Imaging is mainly used if the pain doesn't fit the classic picture or if it's not healing. And if you're found to have a heel spur on an X-ray, know that it's a consequence, not the cause — it doesn't change the treatment.

Treatment: No Miracles, Just Patience

Let's be honest right away: it's long. We're talking 3 to 12 months, with an average around 6 months. Yes, 6 months. It's the kind of injury that makes you want to try everything — insoles, injections, shockwave therapy, osteopathy, magnetic therapy... But from what I've read, the most effective approach remains quite simple: regular stretching and strengthening. Consistency is key.

Calf Stretches: The Basic Thing That Works

It sounds too simple to be true, but calf stretches are truly what comes up most often in the literature as an effective treatment. Two exercises in particular:

• The straight-leg calf stretch (against a wall) — this targets the larger calf muscle (gastrocnemius)
• The same exercise but with a bent knee — this targets the soleus, the deeper muscle.

The classic protocol: 3 sets of 30 seconds, 3 times a day. Yes, 3 times a day. It's demanding, but apparently, consistency makes all the difference — doing it occasionally won't do much good.

Another useful trick: before putting your foot on the ground in the morning, pull your toes back towards you for 30 seconds (foot crossed over the opposite knee). This « pre-stretches » the fascia and reduces that infamous first-step pain.

Strengthening: That's the Real Long-Term Treatment

If I had to take away one thing from everything I've read, it's the Rathleff protocol. The principle: slow, heavy-load heel raises with a rolled towel under the toes. It's a strength training exercise that « forces » the fascia to gradually rebuild itself. According to studies, it yields better results than stretching alone.

You can also work on the small muscles of the foot: toe gripping exercises, towel curls with your feet, walking barefoot at home... I'm not sure if this is as well-proven, but it seems logical to me: if the foot muscles are stronger, the fascia is less stressed.

Insoles: A Helpful Band-Aid

Orthotic insoles or gel heel cups can really provide relief — especially for daily wear. But from what I've read, there's not a huge difference between custom orthotics costing $200 and prefabricated insoles costing $30 for most cases. My pragmatic advice: start with gel heel cups from a pharmacy. If they help, great. Use them as a temporary crutch while the strengthening takes effect, not as a definitive solution.

What Seems Doubtful or Risky to Me

Cortisone injections provide quick relief (2-4 weeks), but there's a real risk of fascia rupture. More importantly, they don't address the root problem — tissue degeneration. Fewer and fewer doctors recommend them as a first-line treatment. Shockwave therapy yields variable results — it might be worth trying if nothing else has worked, but it's not the first thing to try. Surgery is truly a last resort after 6-12 months of all other treatments failing.

Running with Plantar Fasciitis: Possible Under Conditions

Good news: unlike a stress fracture, you can often continue to run. The rule I've learned: as long as the pain stays below 3-4 out of 10 and doesn't worsen from week to week, it's manageable. However, you must accept reducing your mileage by 30-50% and slowing down your training paces for a few weeks (or even months).

My advice: before each run, do 5-10 minutes of progressive walking, then your calf stretches. This small warm-up ritual makes a real difference in pain during the run.

Relapses: The Real Challenge

This might be the most important takeaway from this article: plantar fasciitis apparently has a fairly high relapse rate — around 30-40% within a year of healing. Why? Because people stop strengthening as soon as the pain disappears, and they resume their previous mileage.

My opinion: calf and foot stretches and strengthening should become a permanent habit, not just a treatment. Like brushing your teeth. In parallel, vary your shoes, maintain a relatively high maximum aerobic speed (170-180 steps/min), and most importantly, don't increase your mileage haphazardly. Estimating your maximum aerobic speed also helps avoid consistently running too fast — a classic trap that overloads everything.