A lot of women shy away from high-intensity cardio exercise because they feel that their level of fitness is too low to handle it. While it certainly is very challenging and shouldn’t be attempted by anyone with a medical problem unless cleared by a physician, the fact is that anyone, of any fitness level, can do and benefit from high-intensity cardio. The important thing is to understand exactly what it is and how it affects your body.
First of all, how do we define what is and isn’t high-intensity? Well, that’s a bit like asking how long a piece of string is. But generally speaking, the theoretical definition is that high-intensity cardio is cardio exercise that focuses on your anaerobic energy system, rather than your aerobic energy system. That occurs when you work out at a heart rate of about 80-100% of your maximal. This range covers the 2 training zones often referred to as the Anaerobic Zone and the Maximum Effort Zone.
You can work out your own personal cardio training zones by using our Training Zone Calculator.
So much for the theory.
The important thing to understand is that term “high intensity” actually means different things to different people. One major complication is that the fitter you are, the less your heart rate increases for a given amount of effort. For example, back when I started jogging, I would jog for 30 minutes or more with my heart rate at 90-100% of my maximal heart rate. That’s because I wasn’t fit at the time. Someone who is in shape would never be able to do that, because they wouldn’t be able to get their heart rate so high for an extended period of time.
According to the theory, that should have placed me well into my Anaerobic/Maximum Effort Zone, which would mean I couldn’t sustain that effort for more than a couple of minutes at the most. Clearly, that wasn’t the case. I would occasionally do short sprints, at the end of a jogging session for example, where I was running at what I considered to be a high intensity and definitely in my Anaerobic/Maximum Effort Zone, and that would take my heart rate over its maximal level.
Now, I certainly don’t suggest that everyone make a habit of exceeding their maximal heart rate – I’m not a doctor and I can’t say how safe or unsafe that is. Each individual needs to listen to their body and decide for themselves, in consultation with their doctor if necessary, what a safe limit is for them.
But what this tells us is that there are really two definitions of the term, “high-intensity”. The first is the theoretical definition, which is based on your heart rate as I’ve just discussed, and the second is the personal definition, based on how hard you feel you’re exerting yourself.
As you’ve probably gathered, someone whose fitness level is low will most likely be limited by the first definition (their heart rate) – for safety reasons. But as their fitness level improves, they will reach a point where their high-intensity cardio will be limited by how hard they can push themselves, and they don’t need to be concerned with their heart rate any longer.
So the bottom line is that anyone can get involved with high-intensity cardio training at some level. You don’t need to be able to run 100 meters in 10 seconds to hit a high intensity level, for some people it can happen walking briskly up a moderate grade. High-intensity training has many benefits, including accelerated calorie burning, accelerated improvement in fitness, and development of mental strength.
Try incorporating some in your fitness program today, regardless of what level you’re at!