Performance Benefits

VO2 Max

VO2 max is the maximum amount of oxygen intake, it is one of the key factors for performance in endurance sports and a good marker of cardiovascular health. This increase in VO2 max is due to numerous physiological adaptations including, and increase in stroke volume, maximal cardiac output, maximal a-vO2 difference (improved gas exchange), capillary density, increased red blood cell volume and hemoglobin mass. All this means that our ability to carry oxygen is improved, meaning improvement in cardiovascular performance. (1)

This all might sound very technical, but understanding the fact that when we do HIIT it creates physiological adaptations to our heart, helps us understand why it’s beneficial. This is often so obvious with resistance training, when we lift weights we see our strength increase and see our muscle grow. The adaptations can be more “hidden” within us when we develop an excellent cardiovascular system.

Therefore if you are looking to improve your cardiovascular performance, you need to be performing HIIT on a regular basis (1-2 times a week). Alongside other styles of cardiovascular training including low and medium intensity training sessions. This increase in VO2 max from these short outputs can also help improve endurance efforts as a higher intensity can be maintained for extended periods of time.

Health Benefits

Glucose Tolerance and Insulin Sensitivity

The role insulin plays in maintaining normal glucose homeostasis is crucial to our health and if this ability is degraded through poor glucose tolerance we put ourselves at risk of type two diabetes. A lack of exercise is known to cause a reduction in glycemic control. Numerous studies have shown that HIIT is effective in both the long and short term for improving insulin sensitivity and glucose tolerance . (2)

Reduced Risks of Multiple Cancers

High intensity interval training has also been shown to reduce the chance of both colon cancer and breast cancer.

Other Health Benefits

For a full breakdown of health benefits of HIIT please read through this meta-analysis . (3)

Sustainable Training

Time Effective

The design of HIIT means the the sessions rarely last longer the 15 minute of out put and 30 minutes in total from start to finish. The major hurdle people have to building an exercise routine is a lack of time, making HIIT a perfect go to option.

Enjoyable

HIIT also has a strange sense of enjoyment attached to it. This can be seen in how the protocols adherence rates is higher than lower intensity cardiovascular training, and also through the popularity of CrossFit and other HIIT style of training. (4)

Issues with HIIT

HIIT is by its nature extremely fatiguing due to the very high intensity, making it a very difficult protocol to perform regularly during the week. This is why doing one or two HIIT sessions during the week is likely the best way forward for long term progression.

It can also be hard when dealing with stress in other areas of life or coming back from a period of being sedentary. This is why doing a mix of low intensity and high intensity cardiovascular output is a very effective way to maintain health and performance throughout the long term, when dealing with stress or injury you can fall back on to the habit of lower intensity outputs and when leaning into your exercise regime you can put more emphasis on HIIT.

References