Tuesday, December 16, 2014

An Easy Way to Gauge Cardio Intensity



It's late morning on a nice slow Saturday. You're at the gym doing your cardio and maybe watching some nostalgic Saturday morning cartoons. Suddenly, a thought smacks you in the face, nearly knocking you off the treadmill...


"Am I accomplishing anything by doing cardio?"

"Am I working hard enough?"

"How hard should I be working?"


Now that you've gathered yourself from nearly being knocked off your treadmill, let's go over a few ways to make sure you're working at a pace that will get you results!


Lactate Threshold

"Lactate what?!" Hang with me for a second. I'm about to drop some science! When we're training to improve how our bodies use different energy sources (fat and carbs), and/or training to improve performance for sports or general fitness and stamina, why we are really training is not only to increase how much work we can do (VO2 Max - another article), we are training to increase the threshold where our bodies turn from using a combination of fat and carbs for energy to mainly carbs. This point where our bodies switch to using carbs for energy is called our "lactate threshold." Basically, it's the point when you start breathing much faster and harder.

The lactate threshold is when our bodies switch from using aerobic metabolism (fat/carbs and oxygen) to anaerobic (mostly carbs and no oxygen). Anaerobic metabolism uses almost entirely carbs for energy. A byproduct of this is lactic acid. A by product of "getting rid" of lactic acid is CO2, hence faster and harder breathing.

Why does this matter? Well, training at or just below this threshold is intense enough to trigger the adaptations in the cells that give us more energy and stamina, make us better fat burning machines, and improve our cardiovascular health. As for sports, training at this threshold raises it. In other words, you can run faster and farther while relying less on anaerobic metabolism, producing less lactic acid and CO2, therefore not becoming out of breath.

As for those who want to lose weight, not only is your body able to do more work without tiring out (which is awesome in itself), your body relies more on fat for energy while exercising and less on carbs. Even though it ultimately comes down to calories in versus calories out, using more fat for energy may help improve our body composition (how much fat we have versus lean tissue). Also, because you are training at a higher intensity (NOT high intensity interval training), you end up burning more calories within your session.


How Do I Know If I'm Training at My Lactate Threshold?

Short of getting blood drawn during an exercise test, since we know that the lactate threshold is the point where our bodies start using mainly anaerobic metabolism and a by product is CO2 which increases how fast and hard we breathe, doesn't it make sense to exercise at an intensity that increases our breathing rate? This is known as the "ventilatory threshold"... the point when you start breathing faster and harder. Ventilatory threshold is an indicator of lactate threshold.

As you can see in the graph below, as exercise intensity increases, your rate of breathing increases. Now you may say, "well duh," but do you notice the point in the line where it sharply increases? That is your lactate threshold (red line) and respiratory threshold (blue line). You can see how the respiratory rate (how hard and fast you're breathing) can be used to indicate, roughly, your lactate threshold.


 

The Talk Test

A very simple way to see if you're training at the right intensity is to try to talk. If you're able to complete sentences without trouble, you're not near your lactate threshold. If you're able to speak in broken sentences like, "today... [deep breath] I was looking all over for my pitbull Fido... [deep breath] I found him hiding in under the porch... [deep breath] so he wouldn't have to go... [deep breath] to the vet."

The goal is to find the point just below where you would become out of breath within 4 minutes or so. Think tough but sustainable.


The Gist

The best way to gauge intensity accurately is by measuring your heart rate. Check out "What Should My Heart Rate be During Cardio?" for more info on heart rate training. But, when if you're just starting or you're out for a jog and don't have your heart rate monitor or you just want a break from measuring things, the talk test is a great tool to use!

Now back to Tom and Jerry!

God bless,

Chris 

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