Dear Knees, I’m sorry: The Problem with Going Full Throttle
By Kelsie Mazur, DPT
This past Saturday, I got a reminder about capacity the hard way. It was the first workout in, since last summer, where I ran intervals outside as part of my CrossFit workout. I run regularly on the Assault Runner (that's the treadmill that looks like a hamster wheel, where the treadmill's movement is powered by the runner). Side note: I highly recommend that type of treadmill. But running outside? That’s a different beast, and my body let me know it. Capacity is your body’s ability to handle a certain amount of stress. Whether that’s lifting a heavy barbell, running a certain distance, or even something as simple as spending hours on your feet. It’s not just about strength; it’s about what your muscles, joints, and tissues are prepared for right now…not what you could do last year or even last month.
When we push beyond our capacity too quickly, our body responds with soreness, stiffness, and sometimes even pain. It’s like flooring the gas pedal on a car that hasn’t been driven in months, yikes! By that evening, and even 2 days later, my ankles and calves were screaming at me, and my right knee had some things to say too. Not in an injury kind of way, but in that “Hey, you haven’t done this in a while, and we’re not used to it” way. It got me thinking about capacity and how often we push beyond what we’re actually prepared for.
We’ve all been there. A friend invites you on a hike and you say yes, even though the last time you hit the trails was…well too long to remember. Or you decide to start lifting heavier, add a new movement, or suddenly ramp up your running miles. It feels fine in the moment, but then the body flips on its “check engine” light. It’s not because you’re out of shape. It’s not because you did something “wrong.” It’s because you exceeded your current capacity.
Why Running Outside Hit Me Differently
Even though I run indoors, the moment I took it outside, I introduced new variables my body wasn’t ready for. The Assault Runner is predictable: same surface, same incline, same feedback with every stride. But outside? The pavement, the changes in elevation, the subtle shifts in terrain, and even the way I subconsciously adjusted my stride all placed new demands on my muscles and joints. My calves and ankles had to work harder to stabilize, and my knee had to absorb forces in a way it hadn’t in months.
This is why soreness or even minor aches, aren’t always a sign of injury, which leads me to the lesson I want readers to take away in the blog this week. Sometimes, it’s just your body adapting to a new stimulus. But if you keep pushing without respecting your capacity, that’s when real issues start creeping in.
Building Capacity the Smart Way
So what’s the takeaway? Whether it’s running, lifting, hiking, or any new movement, our bodies need time to adapt. Here’s how to do it without running into trouble:
Ease in – If it’s been months since you’ve run outside, don’t go straight into sprint intervals. Start with shorter distances, slower speeds, or fewer reps.
Respect different demands – Just because you can squat heavy doesn’t mean lunges won’t wreck you. Just because you run on a treadmill doesn’t mean pavement won’t hit different. Prepare accordingly.
Listen, don’t ignore – Soreness is one thing, but persistent pain is another. If your body is talking to you, don’t just push through. Give it time to recover.
Consistency over intensity – The best way to increase capacity is to build gradually. Small, frequent exposures to a movement are more effective (and safer) than occasional, all-out efforts.
I’m still feeling that knee today, but I know it’s not a problem… it’s a reminder. A reminder that capacity isn’t about what you could do last summer; it’s about what you’re prepared to do today. And that’s something we all have to keep in mind, whether we’re just getting back into training or pushing our limits in new ways.
Did you know that we offer free 1-on-1 injury screens? Wattage Physical Therapy will take an in depth look at your ergonomics, posture, muscle tone, muscle weaknesses, and movement patterns to create a plan for YOU. If this article intrigues you, you can directly email me, Kelsie at Kelsie@wattagept.com. I would be happy to help you start the process of living a life free from pain.