When you first begin to work out, you want to see results as quickly as possible. Who doesn’t want their hard work to pay off fast? Whether you’re exercising to lose weight, change your body composition or improve your endurance, seeing results is a real motivator. When you see and feel those changes occurring, it lights a “fire” that motivates you to work even harder. High-intensity interval training is the ultimate “fire starter” that gets your metabolic fires burning while enhancing aerobic and anaerobic endurance.
If your goal is to maximize the results you get without spending lots of time working out, increase the intensity of your workouts. Some people cling to the idea that the best way to boost their fitness level to increase workout volume. Not necessarily so. Research shows you can get similar and, in some cases, superior results when you ramp up exercise intensity. If there’s a single theme that underlies successful workouts, it’s intensity. How hard are you pushing yourself?
Faster Results with High-Intensity Interval Training?
According to a study published in the Journal of Strength and Conditioning Research, high-intensity training is the ticket to fast returns. In this study, a group of healthy, college-age adults took part in a HiiT training routine, 30 seconds of high-intensity exercise followed by a rest period of 30 seconds to 4 minutes between active intervals. Using a high-intensity interval approach, the participants increased their aerobic capacity by 6% in only 3 weeks of training. They also experienced improvements in power when tested on a stationary exercise bike. Compare that to moderate-intensity endurance exercise where it takes 4 to 6 weeks to see improvements in aerobic capacity. How’s that for fast and effective?
Is HIIT training for everyone? High-intensity interval training is a challenging workout that can be modified to suit all fitness levels. Even doctors are waking up to the fact that high-intensity exercise offers greater health benefits than light or moderate-intensity exercise. A study published in the British Journal of Sports Medicine showed patients with risk factors for heart disease, including high blood pressure, elevated cholesterol, and metabolic syndrome, benefited more from HITT training than long periods of steady-state exercise at a moderate pace.
Your heart makes similar adaptations to high-intensity exercise as it does to long periods of moderate-intensity exercise but seems to make these modifications faster. One measure of aerobic fitness is V02 max, a measure of aerobic capacity. Some studies show HIIT training improves V02 max more than long periods of moderate, steady-state exercise like long-distance running.
Improvements in How Your Body Handles Glucose
For people with insulin resistance, a condition that’s often a precursor to type 2 diabetes and heart disease, HIIT may be just what the doctor ordered. A study published in the Journal of Clinical Endocrinology and Metabolism showed a single session of high-intensity interval training was superior to moderate-intensity exercise for enhancing insulin sensitivity and blood sugar control. When combined with resistance training and a healthy diet, HiiT offers a drug-free approach for improving glucose metabolism. Plus, the intensity turns on fat-burning hormones like growth hormone, testosterone, and catecholamines that promote fat loss for hours after you’ve finished a HIIT workout.
Improvements in Exercise Endurance
What’s also interesting is the effect high-intensity exercise has on mitochondria, the tiny energy powerhouses inside cells that produce ATP, the energy currency muscles use to fuel movement and cells use to sustain life. Moderate-intensity exercise boosts the number of mitochondria inside cells and bumps up their capacity to produce ATP and use fat as a fuel source, thereby conserving glycogen. This makes your body a more efficient energy producer and improves exercise endurance. The good news is high-intensity interval training does the same thing in a time-expedient manner.
The intensity of HiiT training leads to improvements in lactate threshold too. When you exercise at a high intensity, you ultimately reach a point where lactate begins to build up faster than your body is able to clear it. This point is referred to as the lactate threshold, sometimes called the anaerobic threshold. There are subtle differences between the two, but for or all practical purposes, they’re the same thing. Contrary to popular belief, the build-up of lactate isn’t directly responsible for the burning and profound sense of fatigue you experience when you exercise above your lactate threshold.
What actually explains the burning feeling you get when you exercise at a high intensity? A build-up of hydrogen ions creates an acidic environment that causes fatigue and muscle discomfort. People with a higher lactate threshold can exercise at a greater percentage of their aerobic capacity without accumulating enough lactate and hydrogen ions that they “hit the wall.” They build up less lactate during high-intensity exercise and are better at eliminating it. Lactate threshold is actually a better predictor of success in endurance sports than V02 max. That’s why even long-distance runners can improve their performance in competitions like marathons by adding HiiT training into their routine.
HiiT Training: A Versatile Way to Work Out
The beauty of high-intensity interval training is you can adapt the interval intensity, duration and volume of the active intervals to meet your needs. If your goal is to increase aerobic endurance, choose longer work intervals from 1 to 5 minutes in length. To improve your performance in power sports and increase your lactate threshold, keep your intervals short, from 10 seconds to 30 seconds. The shorter the intervals, the harder you’ll need to push yourself during that interval to maximize the benefits. With active intervals of 20 seconds or less, the goal is to go “all out.”
Another consideration is the length of the active interval relative to the rest interval. If you’re training for aerobic endurance, keep your rest periods short, 10 to 30 seconds, to keep your heart rate up. If you’re training for power and improvements in lactate threshold, use longer rest intervals of 1 to 4 minutes. A “middle-of-the-road” interval workout would have an active to rest interval of 1 to 1 or 1 to 2. As you can see, you can customize the length and intensity of the intervals to achieve different objectives.
The Bottom Line?
HiiT training has similar, and according to some studies, superior benefits to moderate-intensity exercise. With HiiT training, you may also experience improvements in aerobic capacity more quickly. Plus, it’s a real timesaver. Enjoy the benefits of high-intensity interval training!
Journal Strength Conditioning Research. 26: 138-145. 2012.
British Journal of Sports Medicine. Online publication. October 21, 2013.
Fitness RX. February 2015. page 28.
Journal of Clinical Endocrinology Metabolism. 99: 220-228. 2014.
IDEA Health and Fitness. “HIIT Vs. Continuous Endurance Training: Battle Of The Aerobic Titans”
Medicine and Science in Sports and Exercise, 39 (4), 665-71.(2007)
Lactate Threshold Training. Len Kravitz, Ph.D. and Lance Dalleck, Ph.D.
ACE Fitness. “High-Intensity Interval Training”
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