8/10 – Top Reasons to Drop Cardio for HIIT

8/10. Burns 9X More Total Fat Than Endurance Training

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Did you know you can burn more fat doing HIIT than your typical steady-state endurance training, even though burning a fraction of the calories?

It’s true. This is where the con of a ‘fat burning zones’ rises it’s ugly head! You see if we just counted used calories while exercising no- one would ever do weight or resistance training! The important thing to understand is that cardio calories are only burnt while you continue, your burn rate drops back to normal as soon as you step off your treadmill. However, if you spend time pushing yourself your burn rate will continue for hours and hours after your training ends.

A study comparing a 15 week HIIT program to a 20 week endurance-training (ET) program showed that despite its lower energy cost, the HIIT program induced a more pronounced reduction in body fat compared with the ET program.

When the scientists adjusted the numbers so the calorie burn was equal, the decrease in the sum of six skinfolds induced by the HIIT program was nine times greater than by the Endurance training program [13].

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Thanks Jax

Reference Study [13]

Impact of exercise intensity on body fatness and skeletal muscle metabolism
Angelo Tremblay, Jean-Aimé Simoneau, Claude Bouchard
Physical Activity Sciences Laboratory, Laval University, Ste-Foy, Québec, Canada.

Abstract
The impact of two different modes of training on body fatness and skeletal muscle metabolism was investigated in young adults who were subjected to either a 20-week endurance-training (ET) program (eight men and nine women) or a 15-week high-intensity intermittent-training (HIIT) program (five men and five women). The mean estimated total energy cost of the ET program was 120.4 MJ, whereas the corresponding value for the HIIT program was 57.9 MJ. Despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the ET program. When corrected for the energy cost of training, the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program. Muscle biopsies obtained in the vastus lateralis before and after training showed that both training programs increased similarly the level of the citric acid cycle enzymatic marker. On the other hand, the activity of muscle glycolytic enzymes was increased by the HIIT program, whereas a decrease was observed following the ET program. The enhancing effect of training on muscle 3-hydroxyacyl coenzyme A dehydrogenase (HADH) enzyme activity, a marker of the activity of β-oxidation, was significantly greater after the HIIT program.
In conclusion, these results reinforce the notion that for a given level of energy expenditure, vigorous exercise favours negative energy and lipid balance to a greater extent than exercise of low to moderate intensity. Moreover, the metabolic adaptations taking place in the skeletal muscle in response to the HIIT program appear to favour the process of lipid oxidation (fat usage).

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