Updated: Aug 23, 2021
Understanding the different effects of Cardio, HIIT, and Sprints is important.
Why do them? When to do them? Which one is best?
As a fitness professional, personal training clients and from my own experience, these are the main things to know. About a 3-min read! 👀
Cardio vs. High-Intensity Exercises
Let's divide exercises into two categories for this discussion.
CARDIO - Low to moderate intensity, called “Cardio”. This is a traditional type of exercise such as jogging or walking. It involves only the aerobic process (with oxygen) and doesn't activate the anaerobic process (without oxygen). Since the anaerobic process is not activated, there is no increase in key fitness hormones (Testosterone and Human Growth Hormone). If you are trying to lose weight, cardio requires you to exercise for prolonged periods with a near-starvation diet. But, doing cardio-only, muscle loss can happen. And with muscle loss, there's usually weight regain due to decreased metabolism.
High-Intensity Exercise can be divided into two categories:
HIIT, often called “boot camp”, involves the aerobic process and does activate some anaerobic processes. The results with HIIT are better than with cardio-only or low-intensity exercise, which fails in weight loss and maintaining muscle. HIIT increases calorie burning and increases muscle mass, which helps maintain a higher metabolism. But, HIIT does not increase your Human Growth Hormone and Testosterone levels as much as a Sprint workout.
Sprints are the ultimate program to increase the key fitness hormones (Testosterone and Human Growth Hormone). A 'Sprint 8' for example (a protocol I've adapted that eliminates the need for machines), is very much like Tabata programs, which are designed with specific work and rest time.
Borrowing from the world of pharmacology, think of exercise as a “dose:” too little has no significant effect, while too much is harmful.
When you use "sprinting" workouts for 18-20 minutes, 2-3 times per week, it delivers superior results. Less time with fewer workouts is ideal, especially when you have a busy schedule.
In a Sprint 8, the exercise needs to be simple so you can go at your highest level of intensity for only 30 seconds, and then actively recover for 90 seconds for 8 rounds or intervals: Warmup, 30 work/90 recovery/x8 rounds, cool down. Intensity here means the 30 seconds should be truly physically tough exercise. All-out maximum effort.
The way to know for sure you are doing a true 'Sprint', with your body releasing growth hormone and testosterone, is gasping for air and entire body fatigue when you finish the 30 seconds. The best is active recovery is for 90 secs. But, to do this correctly for the 8 rounds, it's important to have some type of score or power-output as a reference point (such as counting reps) so you can work harder, beat your number each round, and see progress over time.
Try this! My clients are often surprised how much more intensely they find themselves working out compared to HIIT, but love the feeling and results. You're in competition with yourself! Sprint 8 training increases human growth hormone, testosterone, insulin growth factor, IGF binding protein, and lactate. This all results in increased lean muscle mass, decreased body fat, and higher energy.
All My Best,