Have you ever heard of the term HIIT? What about LISS? Intervals? Fat Burning Zone? All of these terms revolve around one thing: cardio. There are many different forms of cardiovascular exercise. HIIT refers to High Intensity Interval Training, while LISS refers to Low Intensity Steady State. Both forms of exercise can help you improve your overall health and fitness. Let’s look at both of them in a little more detail.
Cardio workouts usually gravitate around heart rate and aim to increase it for periods of time. Heart rate is a key indicator of what type of fuel your body is using during any activity — and we don’t mean gasoline! There are three main types of fuel that your body utilizes every single day. These are carbohydrates, fats, and proteins; the three powerhouses of energy supply. Of these substrates, your body loves to use fats and carbs for energy. It can also use protein for energy, but prefers to use it to build muscle tissue. Fats are stored in the body for later, and can be used as energy when required. Carbs are found in our bloodstream as glucose and get stored in the liver and muscles as glycogen, as well as being used for that high intensity quick burn during exercise. Fats, on the other hand, are more for a low intensity burn, and we typically use them for our usual, daily activities. When we exercise, our body uses up stored (or freshly eaten) carbohydrates first because it’s quicker and easier to access that energy. Once those stores are used up, our bodies then move on to the fats.
High Intensity Interval Training (or HIIT), is exactly what it sounds like. A high intensity means training at a level within 70-90% of your maximum heart rate for a period of time. When we say maximum, we don’t just mean a little out of breath. We mean lungs burning, muscles on fire, trying hard to the MAX!
Training at this intensity for one consistent block of time can be exhausting for the body as well as the mind. In turn, research has found that training in this manner, with short blocks of recovery in between, may increase your VO2 max, and thereby improve your cardiovascular fitness. This means you’ll be able to run faster for longer periods of time. HIIT is also an effective way to lose weight. Although HIIT initially does not burn as much fat as LISS, your body spends the rest of the day (sometimes up to 38 hours after your session) working to make up for all the energy that was utilized. As it works to replenish the body throughout the day, it burns even more fat! That sounds much more worthwhile than your usual workout, right?
Low Intensity Steady State training, also known as LISS, refers to maintaining a steady heart rate and pace throughout your workout. The benefits include the ability to train for longer periods of time, and that your heart rate is easier to maintain and keep track of. A LISS workout will typically have your heart beating at a rate of 60-70%; that’s called the fat burning zone, and it’s exactly what it sounds like.
In theory, our body utilizes more fat than carbs when working out at a maintained lower heart rate. Therefore, cardio that’s undertaken at this lower pace results in more fat burn than carbohydrate usage. This is a great way to start building up your fitness level, but after a while it’ll become too easy for your body, and you’ll burn less fat. That’s when you can start incorporating more HIIT workouts into your week; you’ll build your cardiovascular fitness and burn more fat throughout your day.
Active recovery is a rest day that involves some light movement, and a LISS workout is an excellent form of this. You’re recovering from your high intensity workout from the previous day, but actively doing so. Usually after exercise, your muscles will be sore, but studies have shown that just some light movement in the body reduces soreness and is better for recovery than sitting still.
When you move, fluid is sent throughout the body via the bloodstream. This rush of nutrients heads to the muscles, joints, tendons, tissues, and everywhere else, helping your body to recover quicker. Stretching and yoga are excellent forms of active recovery, as they increase fluids to the joints and muscles as well.
Next time you’re feeling a little sore the day after an awesome HIIT class, try a LISS workout at around 60% of your max heart rate. For most people, this will be a semi-brisk walk. Not only are you adding to that recovery, but you’re also adding to the fat burn.
Maddy has worked in the health and fitness industry for 5 years. She has a bachelors in Exercise Science and has recently received her Masters in Exercise Physiology. She has worked with a wide demographic of clients as a Personal Trainer and loves helping people reach their goals and continue to grow. She is an outdoor enthusiast and dedicates her workouts to rock climbing, hiking and whatever new experiences may come her way.
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