Needless to say, if you’re currently involved in a CrossFit program or have tried it in the past, then you know that oen of the foundational priciples behind CrossFit is “High Intensity”…

To start I think it might be a good idea to discuss what is Intensity, and more importantly how do we measure intensity? By the loudness of the music we play? By the awkwardness of the faces you make? Not so much…

In the world of exercise science, researchers measure intensity two ways: 1) By testing the amount of oxygen you are taking in during a giving activity (known and VO2) or 2) By monitoring the increase in Lactate in the blood stream during exercise. To correctly perform either one of these methods in a non-clinical setting would be completely ridiculous. For the first one – you have to be hooked up to a mask, for the second one – you would be getting stabbed in the ear lobe every minute to test your blood lactate levels.

As mentioned in a previous post by Rob, CrossFit makes measuring intensity much easier. To measure intensity the CrossFit way, we have a given load (the weight your lifting) a giving movement standard (squat, thruster, burpee) and a clock to monitor how long it takes you to perform the prescribed workout. Putting this all together shows us that the faster we complete a given workout, at a given load - the higher our intensity.

But why is it so important to workout at a high intensity? Why are the coaches always yelling at my to get my hands back on the bar? Well, working out at high intensity is by far the most effective way to improve both muscular strength and cardio-respiratory fitness. This is accomplished in the following ways:

1. Increased EPOC or Excess post-exercise oxygen consumption (EPOC, informally called afterburn) is a measurably increased rate of oxygen intake following strenuous activity intended to erase the body’s “oxygen debt.” To ”re-pay” the energy expended and oxygen debt created by an intense exercise bout our bodies metabolic rate is elevated. Restated – you burn more calories during recovery to bring your body back to a resting state. Many studies have demonstrated a linear relationship between intensity and EPOC. The relationship being – the higher the intensity, the greater the EPOC. How do we apply this? Well, the harder and faster you workout the more that workout will continue to benefit you throughout the day and even the week.

2. Increased anaerobic threshold or lactate threshold - As exercise intensity increases, your bodies ability to use oxygen metabolize fuel (specifically Carbs) becomes detrimented by lactate production. To hit your lactate threshold, you have hit the point where your body can no longer continue to remove the build up of lactic acid in the blood stream. This build up produces hydrogen ions thus leading to the inability to produce muscle contractions (fatigue).  This is the point where you are forced to back off or slow down (or drop the bar). How do we use apply this information? Well, research has shown and I’m sure you as an athlete have experienced the ability to push hard, farther or longer under high intensity situations. This increased tolerance to operate above your lactate threshold is extremely beneficial to building a leaner, stronger, and faster athlete.

Paired together – improved LT and increased EPOC make high intensity activities much more benificial then your low intensity or steady state activities such as running or walking. Unfortunatly, working out at high intensities can be “unformforable” for most people. It can be down right painfull! So, hold yourself in high regard – your ability to come in and kill yourself day-in and day-out is only doing wonders for your body!

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A. Power Snatch 5-5-5

B. AMRAP 12 Min

10 Deadlifts (135/95)
10 Burpee Box Jumps (24/20)
10 Front Rack Lunges (5 each leg) (135/95)