Why the 10% Rule Doesn’t Work — And How I Keep My Athletes Injury Free

A new client recently asked me how I’d build them up for their marathon in January 2026. Specifically, they brought up the “10% Rule.”

If you’re not familiar, the 10% Rule is the idea that you should never increase your weekly mileage by more than 10% to avoid injury. On the surface, it sounds reasonable — even smart. But if you’ve ever trained with me or heard me talk about coaching, you know where this is going:

We are all different, and we need different inputs to reach our individual goals.
So my take? The 10% Rule completely misses the mark.

In fact, a recent study** of over 5,200 runners — with 22% female participants and an average age of 45.8 years — showed that even small mileage spikes can significantly increase injury risk. A 10–30% jump led to a 64% increase in injuries, while spikes of 30–100% led to a 52% increase (yes, slightly lower — welcome to the messiness of human data). And jumps of more than 100% in a single session? That was linked to a 128% increase in injury risk.

It’s clear: arbitrary mileage bumps, even small ones, can be risky if they don’t match your current training load, history, and recovery capacity.


One Size Never Fits All

Let me give you an example. I worked with an athlete last year who’d been running marathons for years using a free online plan. The plan followed a simple progressive mileage model — likely influenced by the 10% Rule. But despite being consistent, they were constantly dealing with overuse injuries.

When they came to me, our priority was to train smarter — not just harder. We built their plan around them — their history, strengths, schedule, and feedback. Fast forward: they not only stayed healthy, but they ran a PR at the California International Marathon and qualified for Boston.

So, why doesn’t the 10% Rule work?


It Ignores Individual Variability

No two athletes are the same. Some adapt quickly to higher mileage, while others need more time. Sticking to a strict 10% increase could either:

Hold someone back unnecessarily, or push someone into injury territory. Your training should reflect your unique physiology, history, and recovery ability — not a cookie-cutter formula.


It Doesn’t Account for Life

Mileage isn’t the only stress your body is handling. What about: Sleep (or lack of it)? Work deadlines? Family stuff? Weather? Terrain?

If you increase your mileage by 10% and add an extra speed session and only sleep 4 hours a night… that 10% just became a lot more than your body can realistically absorb. Context matters. Always.


It Discourages Intuitive Training

Blindly following a plan can train you to ignore your body’s signals.

Another athlete came to me training for their first 50K. They were terrified they wouldn’t finish, so they stuck religiously to an online plan based on — you guessed it — the 10% Rule. When their body started sending warning signs (fatigue, soreness, nagging pain), they kept pushing through.

The result? Injuries and water jogging as their only cardio for the last month.

Soreness, pain, fatigue — that’s feedback. You need to pay attention to it, not override it.


Progress Isn’t Linear

Your fitness doesn’t go up in a straight line. It’s more like a squiggly one: progress, plateaus, setbacks, breakthroughs. Some weeks you’ll feel unstoppable. Others, you’ll feel like a slug. That’s normal.

If you expect to increase every single week, you’re setting yourself up for frustration — or worse, burnout.


Long-Term, It’s Just Not Sustainable

Even over a 12-week training cycle, a consistent 10% increase (with deloads) leads to a 135% jump in mileage. That’s a lot.

Unless you’re starting at very low mileage, most runners simply can’t — and shouldn’t — handle that kind of build. Eventually, the math just doesn’t add up to sustainable, injury-free training.


So What Does Work?

My approach with athletes is based on adaptation, not arbitrary rules. Here’s the framework:

Keep mileage steady for three weeks.
Deload for one week.
If those three weeks felt strong and manageable: bump up mileage — a good starting point is 10%, and sometimes by a bit more than 10%.
If they felt anything other than great for those three weeks: a smaller increase (5%) — or maybe none.
If signs of fatigue or overuse show up: we don’t increase, and we might even back things down.

This model respects the body’s natural rhythms and allows time for adaptation. It’s sustainable, personalized, and — most importantly — it works.


Run Your Race

If there’s one thing I hope you take away from this, it’s this: training isn’t about following rigid rules — it’s about learning to listen to your body. The 10% Rule is a fine starting point for beginners, but it falls apart quickly for real-world athletes with real-world lives.

So ditch the rigidity. Tune into your body. Trust the process. And train like the unique human you are.

If you’re getting ready for an endurance event — don’t wait until the last month to reach out. The earlier we start, the better we can understand how your body responds and get you to the start line strong, healthy, and ready to crush it.

Let’s build you up — the right way.

**https://bjsm.bmj.com/content/early/2025/07/07/bjsports-2024-109380

How much running is too much? Identifying high-risk running sessions in a 5200-person cohort study

 

Breaking Aging Limits: Why Female Triathletes Over 40 Should Consider Creatine

In 2018, at 41 years old, I was at a personal fitness high. I had qualified to represent Team USA at the World Multisport Championships in Odense, Denmark for duathlon. I was running 6:30-minute miles with ease, holding 21 mph on the bike, and lifting what I thought were heavy weights. I felt strong, fast, and in control.

Then COVID hit.

Like many athletes, my race calendar disappeared, and over the next couple of years, so did some of my fitness. When I decided in 2023 to refocus my training, I expected a bit of rust—but I wasn’t prepared for the storm that followed. Suddenly I was dealing with wildly uncontrolled periods, sleepless nights, severe hot flashes that forced wardrobe changes multiple times a day and night, and—perhaps most frustrating of all—a body that just wouldn’t recover like it used to.

Eventually, I realized I had entered perimenopause.

With that knowledge came change. I began small: limiting screen time before bed, swapping hot coffee for cold fluids in the afternoon, cutting back from four cups of coffee to two, and dialing back processed sugar. Blood work revealed deeper needs—vitamin D, K, B vitamins, and some other stuff I wasn’t ready for.

Even then, the progress was slow—then, I connected with Midi Health, a platform focused specifically on women’s health, and they really know their stuff for women over 40. With their guidance, I added hormone therapy. The combination of lifestyle changes, targeted supplements (omega-3s, iodine in addition to vitamin D, K and a B multivitamin), and HRT was a turning point, but still something was missing. My hot flashes were nearly gone, my brain fog had lifted and the sun was shining through, but I was still sluggish in my training and needed more recovery than ever before. It wasn’t until I added in the BCAA's and creatine as daily supplements that I noticed improvements in my fitness, not just my overall health.

Today, I’m back to running 6:45 miles, biking at 21 mph, and lifting heavier than ever—165-pound back squats and 190-pound deadlifts—at 120 pounds and 19% body fat. And I’m here to say this: creatine was one of the quiet powerhouses in my return to sport.

Triathlon, Aging, and the Female Physiology

According to the Endurance Sports Participant Study by Eventbrite (2014), participation in endurance sports is growing among women, particularly those between 35 and 54. For us triathletes, who juggle the demands of swim, bike, and run, aging brings unique challenges: reduced muscle mass, slower recovery, and fluctuating hormones. These factors make strategic supplementation not just helpful—but potentially essential.

Enter creatine, a supplement long misunderstood as a muscle-builder for male weightlifters. New research suggests it could be just as beneficial—if not more so—for female endurance athletes, especially those tackling the physical and mental rigors of triathlon in their 40s and beyond.

Creatine is More Than a Muscle Builder

Creatine has been pigeonholed as a gym supplement, but the science paints a much broader picture. Studies by Cooper et al. (2012) and Buford et al. (2007) highlight creatine’s role in improving energy metabolism, muscle function, and high-intensity performance. For triathletes—who regularly push through hard intervals and long endurance sessions—these benefits are directly applicable.

But there’s more: Candow et al. (2023) and Rae et al. (2003) connect creatine to brain health, improved memory, and cognitive resilience. That’s especially relevant in triathlon, where focus, pacing strategy, and mental stamina are just as important as physical strength.

Endurance Performance and Creatine

One reason endurance athletes have avoided creatine is the fear of water retention or unnecessary weight gain. But recent studies are challenging that notion.

• The 2023 meta-analysis by Fernández-Landa et al. shows that creatine supplementation enhances endurance performance, especially by improving time to exhaustion and training capacity in already fit individuals.
  
  

• Gras et al. (2021) also found improvements in VO₂ max—a key indicator of aerobic fitness and a cornerstone metric for triathletes.
  
  

These findings are particularly valuable for older women, who may face natural declines in muscle power and mitochondrial function. Creatine can support both, allowing triathletes to maintain intensity in training and efficiency on race day.

Debunking the Myths of Hydration, Cramps, and Safety

Many triathletes have heard myths: creatine causes bloating, cramps, or even kidney issues. However:

• Dalbo et al. (2008) and Lopez et al. (2009) found no evidence linking creatine to dehydration or heat-related performance issues—even in endurance conditions.
  
  

• Long-term studies, such as those by Kreider et al. (2017) and Poortmans & Francaux (2000), affirm creatine’s safety, including in older adults, when taken at recommended doses.
  
  

As for the “bulkiness” myth? While creatine does increase intracellular water in muscle, this doesn’t translate to bloating or mass gain in endurance athletes. In fact, this extra hydration may support thermoregulation—a bonus during hot races or long bricks.

What About Women Specifically?

Historically, most supplement research has focused on young men. But that's changing. As Antonia et al. (2021) note, many outdated creatine misconceptions are rooted in research that didn’t include women.

Emerging data shows creatine may offer unique benefits for women, particularly those in perimenopause or menopause. Hormonal shifts impact both muscle and brain function—areas where creatine can offer meaningful support. Bemben & Lamont (2005) suggest creatine may enhance neuromuscular performance during aging—a crucial edge for any triathlete facing the grind of multiple disciplines.

Practical Guidelines for Female Triathletes Over 40

If you're a woman over 40 training for triathlons or other endurance events and considering creatine, here’s what science recommends:

1. Start with 3–5 grams per day: No need for loading phases. Just a small, consistent daily dose.
   
   

2. Stay hydrated: Standard triathlon/endurance sport hydration practices apply, but creatine doesn’t require extra precautions.
   
   

3. Be consistent: Benefits accrue over time, so daily use (not just around races) is key.
   
   

4. Pair it with strength and interval training: Creatine shines when combined with demanding workouts—just like the ones in your training plan.
   
   

Fueling the Next Chapter of Your Over 40 Body

For the growing community of female triathletes over 40, creatine supplementation offers a compelling, science-backed way to optimize training, enhance recovery, and support long-term brain and muscle health. It’s not about chasing youth—it’s about powerfully supporting the body and brain through smart, intentional fueling.

If you need actual results, look at mine. Remember I mentioned I have declining brain function, weakness, increased need for recovery, and after adding in a consistent 5g of creatine, daily, for about 2 months I really started to feel the difference.

Triathlon is as much about resilience as it is speed—and creatine may just be another tool in your endurance toolkit, helping you push longer, recover faster, and stay sharp from swim start to finish line.

1. Eventbrite Report. (2014). Endurance Sports Participant Study. Retrieved from https://eventbrite-s3.s3.amazonaws.com/marketing/britepapers/Endurance_Report_Survey.pdf

2. Cooper, R., et al. (2012, July 20). Creatine supplementation with specific view to exercise/sports performance: an update. Retrieved from https://pubmed.ncbi.nlm.nih.gov/22817979/

3. Buford, T., et al. (2007, August 30). International Society of Sports Nutrition position stand: creatine supplementation and exercise. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2048496/

4. Candow, D., et al. (2023, June 27). “Heads Up” for Creatine Supplementation and its Potential Applications for Brain Health and Function. Retrieved from https://pubmed.ncbi.nlm.nih.gov/37368234/

5. Rae, C., Digney, A., McEwan, S., & Bates, T. (2003, October 22). Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691485/

6. Fernández-Landa, J. et al. (2023, May). Effects of Creatine Monohydrate on Endurance Performance in a Trained Population: A Systematic Review and Meta-analysis. Retrieved from https://pubmed.ncbi.nlm.nih.gov/36877404/

7. Gras, D., et al. (2021, December 3). Creatine supplementation and VO2max: a systematic review and meta-analysis. Retrieved from https://pubmed.ncbi.nlm.nih.gov/34859731/

8. Dalbo, V. et al. (2008, July). Putting to rest the myth of creatine supplementation leading to muscle cramps and dehydration. Retrieved from https://pubmed.ncbi.nlm.nih.gov/18184753/

9. Lopez, R., et al. (2009, April). Does Creatine Supplementation Hinder Exercise Heat Tolerance or Hydration Status? A Systematic Review With Meta-Analyses. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657025/

10. Kreider, R., et al. (2017, June). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28615996/

11. Poortmans, J. & Francaux, M. (2000, September). Adverse effects of creatine supplementation: fact or fiction? Retrieved from https://pubmed.ncbi.nlm.nih.gov/10999421/

12. Antonia, J., et al. (2021, February).Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Retrieved from https://pubmed.ncbi.nlm.nih.gov/33557850/

13. Bemben, M. & Lamont, H. (2005). Creatine supplementation and exercise

performance: recent findings. Retrieved from

            https://pubmed.ncbi.nlm.nih.gov/15707376/

Hot Flashes and Hot Miles: Heat Acclimation for the Endurance Athlete Over 40

 Two short summers ago, I discovered that my body had apparently decided it was a portable furnace. Bedtime became a nightly inferno. I’d overheat so badly I had to change clothes multiple times a night and sleep on ice packs like some sweaty, menopausal snow leopard.

But it didn’t stop there. My waking hours joined the heat wave party. Midday “heat storms” left me drenched, drained, and sometimes skipping training altogether—not because I was lazy, but because I felt like my core temp was sponsored by a dying star.  At one point, even my scent changed. Yes, ladies, it can happen: when estrogen levels plummet and testosterone doesn’t follow suit, you may find yourself with the aroma of a gym sock in a hockey bag.

One day, after pushing through a CrossFit workout, I came home… ripe. My 14-year-old cat, normally a loyal shadow, sniffed me, gave me the “what-fresh-hell-is-this” face—ears back, lip curled—and didn’t want her normal cuddles. That was my wake-up call. It was time for change.

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🔥 The Heat Is On: Why Acclimating Matters

So what’s happening to our bodies after 40—and why is the heat so pronounced?

• Aging slows our cooling system: We sweat less efficiently, and our bodies don’t regulate internal temp as fast as it used to.
  
  

• Estrogen is peace-ing out: Hormonal decline means reduced blood flow to the skin, impairing our ability to shed heat.
  
  

• Hot flashes and heat training don’t mix well: Surprise sweat attacks mess with consistency and motivation.
  
  

• Dehydration risk rises: The thirst signal weakens, and fluid absorption slows—this can tank performance and recovery.
  
  

• Recovery time increases: The older we get, the more our bodies need smart recovery—add heat, and it’s going to take longer.
  
  

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🧠 Smart Strategies for Training in Heat, with Changing Hormones

Here’s how to train with the heat instead of fighting it like a gladiator in a sauna.

1. Start Small and Progress Slowly

• Begin with either shorter bouts or lower intensity workouts during the adaptation phase when training in the heat of the day.
  
  

• Build up slowly over 14 days or more—your body needs time to adapt.
  
  

2. Hydrate Like It’s Your Job

• Aim to drink before you're thirsty. Carry a bottle around with you
  
  

• Use electrolytes. An example of a workout up to 90 minutes: Start with a sodium solution of 250 mg combined with 4 grams of carbohydrate plus potassium, magnesium and calcium. This will help shuttle water through the intestines into the vessels better than over the counter drinks mixes that have a higher carb solution,  above 3.5% is considered high. The above example can be as simple as 1/16th tsp of salt with 1 tsp of maple syrup in 16 ounces of water. 

• Pro tip: Most sports drinks are too concentrated with sugar to allow the water to be absorbed. Make sure if you like to drink your calories, you ALSO have a bottle with just electrolytes. 

• Post-menopausal women may need to monitor sodium loss more closely, especially if you’re a salty sweater. Meaning you may need more salt than this suggestion. To find out what you need you can take a sweat test.
  
  
  

3. Pre-Cool Before You Boil

• Use ice towels, frozen water bottles down your sports bra, or a chilly drink before workouts.
  
  

• Wear loose, light-colored gear. Tight black leggings at noon? Bold choice. Regretful one possibly. Having the ability for air to flow will allow cooling to happen better.
  
  

• Pro hack: Toss your bandana or handheld water bottle in the freezer before you head out.
  
  

4. Time It Right

• In the beginning, Train early or late—before the sun reaches “surface of Mercury” levels.
  
  

• Save the heat training for your zone 2 and 3 levels of output. You’re trying to build resilience right now.
  
  
  

5. Know Your Limits, And Your Laundry Threshold

• If your heart rate is unusually high for extended periods of time, or you feel lightheaded, cut it short.
  
  

• Be mindful of warning signs: chills, goosebumps, nausea, dizziness, the feeling you’re on a tilt-a-whirl while out at sea.

• Beta-alanine can be used by women in the menopause transition who suffer hot flashes. A dose of beta-alanine, which helps open your blood vessels, before you head out can help ward them off and help your body shuttle blood where it needs to go to keep you cool. The typical recommended dose is 4 to 6 grams. Some people get pins and needles sensations at the higher end of that recommended dose. So start low.

• Don't forget sunscreen - sunburn reduces your skin's ability to cool you.

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💪 Final Words for Keeping Your Sanity while your body and the environment is on fire

So yes, it’s hot. You’re hot. Your cat is concerned. But here’s the thing: you’re not broken—you just have to be more aware and focussed on your adaptation period—especially when your body is behaving like it’s throwing its own climate protest.

Acclimating to heat in your 40s and beyond isn’t just about training harder; it’s about training smarter. It's about honoring your hormones, acknowledging your changing  physiology, and using all the tools at your disposal.

Whether you’re building up for a summer race, chasing PRs, or just trying to stay consistent through another menopausal monsoon, remember: your body isn’t fighting you. It’s talking to you. And now, you know how to listen.

So hydrate, layer smart, pack that ice bandana, and keep showing up. Because while hot flashes might come and go, I want your ability to train and enjoy fitness to stay.