For Tone It Up Tuesday yesterday, we had you perform your tough Lean Legs Pyramid, followed by your SHREDmill workout! We received a few questions (and yes we've heard them before) about why you should stick to your toning exercises first, then finish with your cardio, so we thought a thorough explanation was necessary. Since yesterday's cardio was also a HIIT workout, we'll be able to really get into the science of what makes yesterday's Tone It Up Tuesday workout so effective at stripping down that outer layer of stubborn body fat!

When you exercise, your body relies on three different energy sources to create output. These are the glycolytic system, phosphagen system and the oxidative process. Each of these has their limits, and their benefits.. The first two, the glycolytic and the phosphagen systems are used for intense bursts of energy and output and are used rather quickly within the body. Phosphagen is used first, usually within a few seconds of intense activity, which is why glycogen is also used in parallel. Glycogen is created from carbohydrates taken from your diet and converted in your liver for use in this energy process. This energy is the fastest available and the most readily available for most intense exercises. During exercise, your body will burn through all of the phosphagen and glycogen within your system first before triggering the oxidative energy pathway. Once you reach this point, the body then activates the oxidative energy process, which pulls stored body fat and initiates a process that separates the body fat into fatty-acids and triglycerides, which can then be converted to glucose to power the energy production during your workout.

Since your toning exercise has more of an energy requirement than your HIIT does, it's ideal to perform this first so that you can give it 100%! By giving your all during your toning workouts, your metabolism stays boosted for a longer period of time (during repair!) and you gain that lean long muscle tone you've been working so hard for. After you finish your toning (a ToneItUp.tv workout is perfect to burn through all of your glycogen stores!), beginning your cardio exercise will activate the energy processes that pull stored body fat for use as the energy during your cardio! Wow, this is perfect.. it's exactly what we were looking for. By performing your cardio AFTER your toning workout, you will gain strength and burn fat! Awesome.. now, let's take it to the next level....

Most of us know what HIIT is by now, High Intensity Interval Training, and as you've seen we are both big fans of our interval workouts. By replacing steady-state cardio with intervals each day, we are allowing our bodies to work for us! Here's how it works: By only working out for a brief period of time, you are obviously able to push yourself to work at a much higher rate of output than if you were to go for a long run. When you perform an activity at 100% output for 1-5 minutes, your body will burn through all it's available glycogen, which in turn increases lactic acid buildup, the byproduct of glycogen once it's been used as energy. At the tail end of each interval, your body gets to the point where it screams STOP. This is the point in which your body can no longer provide the glycogen it needs to continue performing the interval at the pace you are pushing at and this is known as the lactate threshold. By working at 100% for each interval, your body will bump up against the lactate threshold each time and in response the body will boost every metabolic process it can to keep up & prepare for more.

Now that you have increased your body's metabolism, it's aerobic metabolism is also boosted to provide energy during recovery periods and it does this by using the oxidative process between sprints and before cool-down to keep up with oxygen demand. Once you finish your workout, your body is in such an elevated metabolic state, the work required to return to RMR (resting metabolic rate) requires quite a bit of energy. This effect is referred to as EPOC or Excess Post-exercise Oxygen Consumption. Since you have just burned through all the phosphagen and glycogen, the energy being used to bring your heart rate, body temperature, and respiratory rate back to resting will continue to come from body fat stores. EPOC can last as long as 24 hours, with the length of time relative to the effort & duration of the exercise you performed.

What's great is that if you don't have time for a combination toning/HIIT workout, you can still get the great fat shredding benefits of HIIT on its own! We created the SHREDmill series of workouts for you because of this exact reason and when you perform them at high enough intensities, you will reach EPOC and burn through that stubborn body fat.

A great question you still may be asking is "How do I know if I've reached EPOC?". Chances are pretty good you have, but you may not have recognized it! Have you ever squeezed in a workout? Be it between class, between meetings, or on your lunch break? You likely ended up having a great workout, jumped in the shower, and left the gym just to start sweating again! That's EPOC! Even after you cleaned off, caught your breath, and left the gym - your body was working so hard during the exercise that it's metabolism is still through the roof and the heat created by the boosted metabolism creates heat, which in turn means you continue to sweat! This is EPOC and the energy being used to calm it down is body fat :)

So to answer your questions ladies, keep kicking butt with your Toning exercises first, then when you've gotten through that, HIIT the cardio ;) we promise you'll love the difference.  K&K

... Remember this video from two summers ago!?  We look like we're 16, haha, but it's all about EPOC & HIIT