On aerobic equipment, heart rate charts, or in fitness magazines, you may see what is labelled as “The Fat Burning Zone”. This is an area around 60% to 70% of your max heart rate that, when maintained during aerobic activity, is supposed to be more beneficial for burning body fat and improving heart health.
We now know that this heart rate range, common for many during steady state cardio, will produce the least amount of reduction in body fat, and the most loss of lean muscle mass, than almost any other activity. In addition, the formula for estimating max heart rate, referred to as the Karvonen formula, acquired by subtracting the individuals age from the number 220, is extremely inaccurate.
A more accurate formula for predicting max heart rate, based on studies in the last few years, would be 211 minus 64% of age. But, even this formula will not account for specific differences between individuals.
Once you have your predicted max heart rate, work at 40-60% of your max if you are warming up, cooling down, recovering on rest days, or attempting to improve your body’s ability to burn fat.
If you want to compete in aerobic events, spend most of your cardio workouts around 70-80%. Keep in mind, this won’t be the most efficient at improving heart and lung health, or burning fat while maintaining lean muscle mass, but it will prepare you for events you plan to compete in.
Finally, if you want to get the best benefit from your time exercising, start doing those high-intensity intervals I mentioned a few posts ago. Warm up for a few minutes and then alternate 30 seconds of intense work, heart rate around 80-95% of your max (based on fitness level), with 30 seconds of easy rest. Alternate these intervals until you feel you could only compete 1 or 2 more, but would rather not, and then cool down.
The interval training should take around 10-20 minutes and will improve your heart and lung health to a greater extent than 2 hours of steady state cardio.
Also, there is the factor of “excess post-exercise oxygen consumption”, or EPOC. For a couple hours following intense exercise, the body’s oxygen intake is increased, aiding in improved hormone function, nutrient partitioning, and cell repair. During this time, the body will access its own body fat stores to release free fatty acids into the bloodstream to be used as fuel.
The numerous benefits of EPOC are significantly lowered with less intense, continuous exercise (such as steady state cardio), or if there are major insulin spikes during the first 2 hours of recovery (so keep carbs to a minimum following high-intensity intervals).
As my experience as a trainer grows, I tend to rely less and less upon a single number such as heart rate, calories, and even bodyweight. There are just too many factors to justify basing a fitness or nutrition program upon numbers predetermined by distant agencies or studies that are reversed every few years.
Plus, I have seen too many people start off with simple calorie counting or bodyweight tracking, and end up becoming obsessed, basing their whole existence upon a single number.
There are endless examples and specific situations I could reference but, simply put, no two people’s bodies are the same and therefore, bodies will behave differently in regard to calories, bodyweight, macronutrients, heart rate, etc.
My favorite method of determining intensity is rating of perceived exertion. I’ll use a scale of 1 to 10, or 1 to 5, or simply say “would you classify this as easy, medium, or hard?”
If a person already has a heart rate monitor on, or has very specific endurance goals, I love having one more number to track. I also like to measure how much time a client’s heart rate takes to return to resting levels, as a way of determining their hearts performance.
However, at the end of the day, it’s just one tool in what is an almost limitless toolbox to track intensity level and progress.
So, if you’re used to tracking heart rate, and know what your optimal ranges are to achieve your goals, stick with it! Conversely, if you are considering spending a hundred dollars and hours of your time on a heart rate monitor and watch, it may not be necessary.
But, as always, determine what will work best for you! And if you need any motivation or professional guidance along the way, feel free to contact me!