HIIT vs. LISS: Which Cardio Training Style is Best?

Time and time again, people will force themselves upon frequent cardio sessions in hopes of burning excess fat before summer comes. Although there have been many research studies proving the superior effects upon fat loss from weightlifting over cardiovascular conditioning, nonetheless, adding in bouts of cardio will still increase total fat loss and caloric expenditure towards your goal. In the realm of cardio training, many forms and styles have been invented and implemented but the two most common methods I see today are: High Intensity Interval Training (HIIT) and Low Intensity Steady State (LISS) cardio.

1) Heart Rate Zones

Your heart rate (HR) is a measure of how many heartbeats per minute (BPM) you are expressing at any given time. During exercise, your heart rate increases along with the exercise intensity and duration. Heart rate zones establish what intensity level you are training at according to your given BPM. Knowing which heart rate zone you are training in can be crucial for targeting fat efficiently. Many people perform cardio to lose weight, however most people don’t actually know what level of difficulty they are truly performing at. First, you need to find your maximum heart rate (MHR) by using this formula: (your age -minus 220).  Once you determine your MHR, then you can find your appropriate heart rate zones for each cardiovascular level.

In general, the purpose for each training zone can be expressed as:

  • Maximizing Performance: Hard to Maximum effort
  • Improving Fitness: Light to Hard effort
  • Losing Weight/Fat: Very light to Light effort

2) LISS (Low Intensity Steady State):

LISS is typically what you see everybody doing in the cardio section at the gym. It is low, slow, and usually done for a long period time. This style of cardio utilizes a high percentage of body fat as energy, but it also has the highest level of training adaptation. This means that your body will get used to this style of cardio much faster than other forms, and therefore, it will no longer provide challenge or have the same fat burning effect. As your cardiovascular level improves through training, your resting and exercise HR will decrease as well. For this reason, you should always monitor your heart rate during LISS cardio. For this style you want to aim to be in the light-moderate phase, about 60-75% of your MHR. This heart rate should be kept during the entire portion of your cardio session.

Benefits of LISS:

  • Low impact and low intensity
  • Great for beginners or those with injuries
  • Can burn high levels of fat/calories

Cons of LISS:

  • Time consuming
  • Boring/low challenge
  • Can cause muscle loss (long duration/frequency)
  • Only burns calories in the moment

3) HIIT (High Intensity Interval Training):

HIIT has become one of the most popular styles of cardio to perform due to its superiority over traditional styles. HIIT combines two phases together in a repetitive pattern during the prescribed amount of time. The two phases includes a: LOW” phase (50-70% MHR), and aHIGH” phase(85-100% MHR). During the low phase, your body uses a higher portion of fat as energy, whereas the transition into the high phase takes your body towards an anaerobic state- ultimately utilizing more glycogen and ATP as energy. Since HIIT challenges three energy systems at once, it expends a tremendous amount of calories and supports fat loss. Typically, the low phase is about double the amount of time as the high phase. A good place to start would be with a low phase of 1-2 minutes and a high phase of 30 sec-1 minute.

HIIT, additionally increases the post exercise caloric burn due to metabolic changes in the muscle’s physiology. When performing HIIT, mitochondrial capacity increases, leading towards higher levels of ATP production and fat loss.

Benefits of HIIT:

  • Lower time duration
  • Higher caloric expenditure as compared to LISS
  • Less adaptability
  • Increases muscle retention
  • Increases metabolic rate/long-term burn

Cons of HIIT:

  • Cannot be performed daily
  • Can increase risk for injury
  • High intensity is not suitable for the elderly or injured population

Regardless of which cardio style chosen, any activity is better than no activity at all! Both LISS and HIIT will burn calories and fat at the end of the day. First, you should decide which style best fits your lifestyle and needs. In my opinion, both forms should be utilized in order to seek maximal benefits. Since HIIT cannot be performed daily, the use of LISS could provide extra benefits, while providing some rehabilitative effects onto your joints as well. Have fun with training and experiment with different methods!

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