VO2Max: What You Actually Need to Know
Right, so after posting about VO2max last week, my inbox exploded with one question: okay Peta, so how do I actually improve it?
Fair call. Let’s get into it.
What actually works
Your cardiovascular system adapts when you challenge it. Simple as that. But here’s what most people get wrong – they think it’s all about smashing yourself with hard intervals. It’s not.
You need two things working together: high-intensity intervals and steady-state aerobic work. Let me explain what I mean.
The interval work – those short, sharp bursts where you’re genuinely working hard – forces your heart and lungs to adapt. Your heart gets stronger, your blood vessels get more efficient, your muscles get better at using oxygen. This is what pushes your VO2max up.
But you can’t do that every day. Your body can’t handle it, and honestly, you’ll just end up exhausted and not actually getting fitter.
The steady-state work – and this is where most people miss the boat – builds your aerobic base. This is your foundation. Without it, you’ve got nothing to build on.
I walk every day. Hills included. I also love a long hike with a pack on to add more challenge. There’s no rush with this work – it’s simply about time on feet, having my heart rate elevated but not maxed out. I’m working, but I could still hold a conversation. That’s the sweet spot.
What happens when you do this consistently? Your cells get better at producing energy. Your heart muscle gets stronger and pumps more efficiently. Your body learns to use fat as fuel so you can keep going longer. Your resting heart rate drops over time – that’s a real sign your cardiovascular system is adapting.
The beauty of this steady work is I can do it most days without needing massive recovery. It doesn’t trash me. I can still train hard when I need to, but I’m building the engine every single day with the walking.
Most research points to needing about 80% of your training in this steady-state zone and 20% in high-intensity intervals. But here’s what I see constantly – people do the opposite. They only smash themselves with hard efforts, wonder why they’re not improving, and end up exhausted all the time.
You need both. The steady work builds the engine. The intervals push what that engine can do.
And none of it matters without consistency. Sporadic hard efforts don’t cut it. You need to show up, week in and week out, for your body to actually adapt.
What I see with my clients
Every month, I measure max heart rate and recovery heart rate with my PT clients. We track these patterns over time because they show us what’s actually happening with cardiovascular fitness – not just what a watch algorithm thinks is happening.
And here’s what I see consistently: women who stick with structured interval work – even modified versions appropriate for where they’re starting – show measurable improvements in both their max capacity and how quickly they recover after effort.
That’s real adaptation happening. Not a number on a screen. Real change in how their cardiovascular system works.
But more importantly? They notice it in daily life. Stairs get easier. They can walk faster without getting winded. They have the energy to keep going when they want to keep going. They’re not exhausted by lunchtime.
That’s the point of all this.
What NOT to do
Don’t jump into intense intervals if you haven’t been training consistently. Build your base first with regular moderate-intensity work, then add intervals gradually.
Don’t ignore recovery. Your body adapts during rest, not during the workout. If you’re smashing yourself every session with no recovery days, you’re not getting fitter – you’re just getting tired.
And don’t compare your “high intensity” to someone else’s. Your intervals should challenge YOU, based on YOUR current capacity. More on that in a minute.
The Confidence Connection
Look, improving your cardiovascular fitness isn’t about chasing a number on your watch or hitting some arbitrary target.
It’s about building the engine that lets you live how you want to live.
When your cardiovascular capacity improves, you expand what’s possible. You can walk further without needing to stop. You can carry things without getting winded. You can keep up with grandkids. You can travel without being exhausted. You can live with full capability to handle whatever your day throws at you.
Your fitness shouldn’t be the limiting factor in your life. Building your cardiovascular capacity means it won’t be.
Move Moment
Right. Enough talk. Let’s give you something practical you can start this week.
Here are two interval frameworks. Pick the one that suits where you’re at right now and what you have access to.
But first – critical point: Your “high intensity” is YOUR high intensity.
What gets your heart rate up and challenges you is different from the person next to you. Your sprint might be someone else’s warm-up jog. That’s completely fine.
The point is working at a level that’s genuinely hard for you – where you can’t hold a conversation, where you’re breathing hard, where it feels challenging.
Don’t compare yourself to anyone else. Just work at your intensity.
Option 1: 8/12 Second Intervals (Cardio-Focused)
8 seconds high intensity / 12 seconds recovery
Choose your approach:
- Sprint to walk (outdoors)
- Stationary bike (fast pedal to easy pedal)
- Treadmill (sprint to slower walk)
How to do it:
- Warm up for 5-10 minutes at an easy pace
- 8 seconds at YOUR sprint pace
- 12 seconds recovery at an easy pace (you stay on your equipment, just slow down)
- Aim for 5 minutes total to start, build from there
- Cool down for 5 minutes
Do this 1-2 times per week with at least one day between sessions.
Option 2: 20/30 Second Intervals (Functional Strength-Cardio)
20 seconds work / 30 seconds recovery
Using light weights in one continuous flowing exercise:
The work interval (20 seconds):
- Start with weights at shoulder height
- Swing the weights down as you lower into a squat
- Power up from the squat and press the weights overhead
- Repeat continuously for 20 seconds
The recovery interval (30 seconds):
- Step-touch-reach (easy movement to keep moving while you recover)
How to do it:
- Warm up with some movement for 5 minutes
- 20 seconds of the continuous squat-swing-press flow
- 30 seconds of step-touch-reach recovery
- Repeat
- Aim for 10 minutes total to start, build from there
The key here is the flowing movement – you don’t stop between the squat and the press. That continuous motion is what keeps your heart rate up and creates the cardiovascular challenge alongside the functional strength work.
Track your patterns over time. Note how you feel, what your heart rate does, how quickly you recover. Over weeks and months, you’ll see the patterns shift. That’s your cardiovascular fitness improving. (And if you want to know how to use your watch data properly to track this, check out Part 1 of this series.)
The goal isn’t perfection. The goal is consistent effort over time, challenging yourself appropriately, and building the capacity to keep doing what matters in your life.
Start this week. Pick one framework. Do it twice. See how you feel. Then keep going.
And don’t forget – this interval work is only 20% of what you need. The other 80%? That’s your daily walking, your steady movement, your time on feet. That’s what builds the foundation everything else sits on.
