High-Intensity Interval Training vs. Steady-State Cardio

Since high-intensity interval training (HIIT) became the cardio to do in the fitness industry, it has been very popular to discredit steady-state cardio and low to moderate intensity cardio training.

‘Cardio Bunnies’ have become the brunt of many gym based jokes. The truth is, they both can have their place within your training programme teamed up with a resistance protocol.

Everybody has different fitness goals, likes and dislikes. So, programming HIIT to someone who doesn’t enjoy it, and has issues adhering with programmes is not going to work. I used to do this. I would tell people HIIT was the only cardio they should be doing, even though I used to row, and spend hours on end on the erg or in a boat because I loved it.

Some people enjoy longer steady state runs, others may enjoy shorter, more explosive cardio training over 20-30 minutes. It’s about finding the balance of what people will enjoy, have the time for and adhere to, and what is going to get them to their end goal. Therefore, in this article I am going to discuss the benefits of both types of cardio training: High-Intensity Interval Training vs Steady-State Cardio.

What is HIIT Training?

HIIT involves pairing periods of relatively intense high-energy exercise with low-effort rest intervals.

Due to its nature, altering the periods of exercise and recovery basically allows you to create an infinite number of interval training workouts.

However, this work: rest ratio should generally be designed to challenge specific energy systems of the body.

What is Steady-State Cardio Training?

Steady-state cardio for this article is continuous exercise for 20 minutes or more. For example, walking, running, cycling or swimming.

Cardiovascular Benefits of HIIT

Improved stroke volume of the heart muscle for both types of cardio methods has been demonstrated. However, HIIT has proven to show around a 10% larger improvement than continuous endurance training (Kravitz, 2012).

Improvement in maximal aerobic capacity (VO₂max) seen after 8 weeks of HIIT training in comparison with continuous cardio (Zwetsloot, K, 2014).

Training at 90%-95% of VO₂max increased left-ventricle heart mass by 12% and cardiac contractility by 13%, similar to that of continuous endurance training (Kravitz, 2012).

Skeletal-Muscle Benefits of HIIT

Increased mitochondrial biogenesis (size and number) – the energy centre of the cell. The increase in mitochondria capacity leads to a greater energy availability for the working muscles which, in turn, leads to greater force production for longer durations. This has been a known adaptation from chronic endurance training. However, studies demonstrate that there are also similar results gained from completing a 6 week HIIT programme (Kravitz, 2014).

Studies have also demonstrated that after just 7 weeks of HIIT, there are higher levels of mitochondrial enzymes leading to improved skeletal-muscle metabolic function. This in turn, leads to more efficient fat and carbohydrate breakdown for fuel during exercise (Talanian, J. 2007).

Metabolic Benefits of HIIT

It has been demonstrated that both continuous endurance exercise and after just 6 weeks of HIIT, there is a shift towards using fat for fuel during exercise. Fat oxidation was significantly higher and carbohydrate oxidation was significantly lower after introducing this exercise protocol (Talanian, J. 2007).

Improvements in endothelial function, insulin sensitivity, and blood glucose has been shown in patients with metabolic syndrome, with no changes in their continuous exercise counterparts (Barclay, 2012).

The increase in ‘excess post exercise oxygen consumption’ (EPOC) is another benefit of HIIT training. After the session is complete, oxygen consumption is still elevated due to the need to restore physiological and metabolic factors in the working muscle cells. This means there is an extended period of calorie burning after exercise has stopped (Zuhl, M. 2012).

How to Make Cardio Exercise More Enjoyable

Adherence to HIIT programmes has been shown to be greater than that of continuous cardio, with feedback suggesting the interval type style of training is much more enjoyable than a longer duration steady state session (Barclay, 2012).

With time as a very popular barrier for many individuals, HIIT training is a great way to introduce cardio sessions for around 20 minutes with, as mentioned earlier, the same, if not greater benefits than continuous cardio (Barclay, 2012).

Summary

When designing an endurance exercise programme, the main aims of this are generally to improve cardiovascular, metabolic and skeletal muscle health. Continuous cardio has generally been the go to cardio until the past few years since HIIT has become popular.

However, incorporating different types of cardio training into your fitness programme will provide the most efficiency. This depends on your client’s goal and what they want to target specifically.

Here are a few extra positives and negatives to each type of cardio training:

1. When in a rush, HIIT is a great session to fit in and provides extra calorie burn post workout. It can also be a great finisher to any other session.
2. When you are fatigued already and need to burn calories without taxing your body, low intensity steady state (LISS) exercise is great to increase energy expenditure throughout the day and easy to recover from. Meaning you can really use your full energy for the main sessions in your programme. This can be done by a simple walk, increasing your non-exercise activity thermogenesis (NEAT).

References

1. De Feo, P. Is high-intensity exercise better than moderate-intensity exercise for weight loss? Nutrition, Metabolism & Cardiovascular Diseases 23, 1037-1042, 2013
2. Kravitz, L. Metabolic Effects of HIIT. IDEA Fitness Journal, 2014
3. Micah Zuhl, MS., Kravitz, L. HIIT vs. Continuous Endurance Training: Battle of the Aerobic Titans. IDEA Fitness Journal, 2012
4. Shiraev, T., Barclay, G. Evidence Based Exercise; Clinical Benefits of High Interval Training. Australian Family Physician 42;12, 2012
5. Tabata, I., Nishimura, K., Kouzaki, M., Hirai, Y., Ogita, F., Miyachi, M., Yamomoto, K. Effects of moderate-intensity endurance training and high-intensity intermittent training on anaerobic capacity and V˙ O2 max. Med Sci Sports Exerc 10: 1327–1330, 1996
6. Talanian, J., Galloway, S., Heigenhauser, G., Bonen, A., Spriet, L. Two weeks of high-intensity aerobic interval training increases the capcity for fat oxidation during exercise in women. Journal Applied Physiology 102; 1439-1447, 2007
7. Zwetsloot, K., John, C., Lawrence, M., Battista, R., Shanely, A. High-intensity interval training induces a moderate systemic inflammatory response in active, young men. Journal of Inflammation Research 9-17, 2014