Interval training is the “super charger” that can accelerate anyone’s health regardless of age or conditioning. Whether your goal is weight loss, blood sugar control, cardiovascular fitness, or Olympic glory, High Intensity Interval Training or “HIIT” as it is called, is a tool that you must explore.
There are dozens of ways to perform HIIT and it can be done by anyone regardless of fitness level. In fact I will be as bold as to say it represents the fastest way to go from couch potato to good health and I recommend it to all of my patients. The actual intensity can be varied to fit the needs of everyone, even cardiovascular patients. So lets discuss it’s origins and just how it works.
Izumi Tabata is a Japanese physiologist who was working with speed skaters. He observed that a well-trained speed skater had to skate hundreds of long grueling miles to reach top competitive form. The physical toll incurred by this type of training caused athletes to breakdown physically and mentally and often lead to fragile athletes prone to injury. He performed a study in 1996 where he had skaters train for very short but very intense periods. It was the increased intensity that pushed the athletes over their previous thresholds to develop greater fitness levels but because the efforts were so short it did not cause the damage of the previously used long sustained efforts. Bottom line was shorter training time with greater result.
Tabata’s magic formula included a warm up followed by 8 short intense maximal output efforts. All out sprint for 20 seconds followed by a 10 second rest repeated 8 times. Done. You are only performing a total of 4 minutes of hard exertion. But you will question your own sanity during that intense 4 minutes.
Other scientist including Professor Martin Gibala at McMaster University and Professor Jamie Timmons at the University of Birmingham followed Tabata’s lead with interval regimens of their own and showed similar results. Gibala used a protocol that called for less intense efforts than Tabata but for a longer time period. He used a 60 second effort at near maximal effort (95%) with a 75 second rest period for 8 to 12 cycles. He later modified this to require only an 80% effort for 60 seconds followed by 60 seconds rest. He demonstrated that a mere 2.5 hours of this type of sprint training spread over several weeks could produce results equivalent to 10.5 hours of traditional endurance training.
Timmons took it a step further and had participants exert an all out sprint for 20 seconds but with a 2 minute rest and only 3 cycles. He had them repeat this three times per week for a grand total of only 3 total minutes of hard exertion per week. He also demonstrated that this type of training was effectively reversing diabetic risk. People with poor insulin function and elevated blood sugars were reversing their disease with this type of exercise. Gibala also demonstrated this effect, reporting a 35% improvement in insulin sensitivity after just 2 weeks of training.
How is this possible? The intensity of this type of exercise is taxing the muscle at a much higher rate and causes adaptations in muscle function. The majority of our insulin receptors and insulin function are found in our muscles as it represents such a massive percentage of our tissue. The muscle becomes a more efficient machine and burns fat calories with increasing ease. The amount of insulin required by the body begins to drop. Recall that the presence of insulin in the body sends a signal telling the body to stop all fat burning operations. So a reduction in the level of insulin is a good thing allowing fat burning operations to increase.
Burn more calories at rest? Yes, the holy grail has been found. After a period of intense exercise the metabolic rate has been greatly elevated and will take 24 hours or more to return to normal. That means you are burning calories at an increased rate hours after you have showered and returned to your normal life. If you had simply jogged for a few miles at a steady pace your metabolic rate would have risen a modest amount but returned to normal within 2 to 3 hours.
So who benefits from this type of workout?
Just about everyone:
- Weight loss is accelerated. Zone 2 training at lower intensities has its place but Zone 2 exists so that we are prepared to engage H.I.I.T. Studies have proven HIIT’s superiority as a conditioning tool.
- Diabetics and insulin resistant patients will improve insulin function.
- Athletes of all levels will increase performance and enhance VO2 Max.
If you are a cardiovascular patient with a history of heart attack or congestive heart failure then work with your doctor to guide you through a safe version of this type of exercise but even cardiac patients can accomplish improved function with a gentler version of this type of exercise.