Cardio 101

 Cardio 101

Have you heard fellow gym members discussing HIIT or LISS cardio training?

What in the world do these crazy acronyms HIIT and LISS mean?

HIIT stands for High Intensity IntervalTraining, which consists of short sprint intervals coupled with low-moderate intensity work. One of the ways we have our client’s incorporate this is to "sprint" on an elliptical for 15 seconds and have an active recovery for the next 45 seconds to bring your heart rate back to normal and then repeating it.

LISS stands for Low Intensity Steady StateCardio, which consists of purely low-moderate intensity work. An example of this would be walking on the treadmill or riding the bike and being able to hold a conversation (we tend to see a lot of this at corporate gyms).

Let’s look a little further at the science and benefits of each…

Why testing the Lactate Threshold (LT) andAnaerobicThreshold (AT) is a good idea?

The AT and LT are extremely powerful predictors of performance in aerobic exercise (cardio). There are two ways that muscle can burn glucose (blood sugars) and that is through aerobic work (with air) and anaerobic work (without air). For example, long bouts of LISS cardio is considered aerobic work and weight training or HIIT cardio can be classified as anaerobic work. The AT and LT are a great test for HIIT and LIIS cardio because it gives a great predictor of which type of work produces ATP (Adenosine Triphosphate). ATP is a quick burst of energy that we get in our muscles when we contract them (Ex: every time you do a bicep curl, you are getting a quick burst of ATP). HIIT produces better changes in exercise capacity as opposed to LISS cardio. High intensity training will hit the AT and LT, that’s what causes the body to make metabolic changes. When you are doing LISS, you are considered below the threshold of AT and LT.

How can I figure out which type of cardio I am doing?

This is a simple test - If you can carry on a conversation, you are performing LISS.

When doing HIIT you are above the AT and LT and when you are above the AT and LT you push for greater improvement in metabolism which thus leads to better fat loss over time. You are also doing HIIT for less duration (20-30 minutes of total work) versus 45-60+ minutes of typical cardio. Save time and better results = win.

How can I improve my metabolism?

1. Adding muscle tissue (getting stronger in the 8-12 repetition range)

Following the progressive overload theory, your body adapts to the stress you place on it, so you must continually find ways to increase the demands you place on your body (shorter rest periods between sets, increasing load/weight used, increasing volume (doing 3 sets instead of 2) or adding in another weight training day.

2. Increase your muscle’s oxidative capacity. Your muscles have these energy producing units called ‘mitochondria’ and this is where ATP are made and fats are burned.

The more mitochondria you have and the more active they are the greater oxidative capacity you will have for fat loss. HIIT increases mitochondrial capacity and you actually increase the amount of mitochondria you produce. Studies show that you get greater fat loss through high intensity training because of the increase in oxidative capacity. Whereas with LISS you’re only burning calories at that precise moment, there’s no 16 - 24 hour energy expenditure (boost in metabolism).

This isn’t the most efficient way to do things. Your body WILL adapt to LISS and you will have to continually increase the duration for the same benefits.

With HIIT you are burning calories during the torture session, but also for the next 16-24 hrs.

Research

A study conducted by Wilson et al. From the University ofTampa, FL, shows when you add in LISS you get a temporary boost in weight loss. Subjects lost a couple of pounds the first week, than weight loss stalled.  This happened because their metabolism completely adjusted to the LISS and that became their new set point to what they had to do just to maintain their current weight.  Do more cardio and eat less? Sounds reasonable but, unfortunately you will most likely end up in a worse position than when you started your weight loss plan. LISS with a low calorie diet is terrible for fat loss and could cause muscle loss.

If you get too aggressive in your fat loss goals (too much cardio, restricting calories) you have a strong possibility of losing muscle tissue.  At some point, you will most likely need to consume more calories and reduce the amount of cardio you are doing. Once this happens, (exercising less, eating more) yourbody will most likely gain weight. Unfortunately, you’ll gain body fat  back and will NOT gain the muscle tissue that you lost. Essentially, you will weigh more and have a higher body fat percentage which equals a “muffin top” and a slower metabolism.

So why does HIIT work so much better than LISS?

HIIT has been proven muscle retention because when you’re doing LISS (ie: walking) you’re not activating muscles the same way as if were lifting weights. So when you sprint you have hip flexion, knee extension, and those are movements performed during weight training (leg workouts) HITT is another way to overload the muscle. Just compare a sprinter’s body composition to marathon runners, more lean muscle mass!

So why/when would be a good time to implement LISS?

I believe in doing both HIIT and LISS.

This is why:

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You can’t do HIIT 5-6 days a week because eventually it will have a negative impact on your weight training thus interfering with lean muscle growth (not good).

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Many people have legitimate orthopedic, and or cardiacreasons to avoid HIIT, so LISS is their only option.

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New gym goers may not have the cardiac endurance, coordination, confidence or a strong enough baseline fitness level to begin with HIIT.

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HIIT could be dangerous if not used correctly and could lead to injury.

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When working around any injury (ies) LISS may be the only form of exercise/cardio you are able to do in a pain free fashion.

I’m a firm believer that both HIIT and LISS cardio each have unique benefits. I feel they both should be incorporated into your routines. Hopefully this article will allow to choose when, how and why you should be doing various cardio modalities.

Christopher R. Tybor

Proud Owner 

ChrisFit Personal Training 

www.ChrisFit.net