What’s your favorite way to work out? Many people like the time expediency that high-intensity interval training offers. High-intensity interval training (HIIT) is an exercise structure that alternates between short periods of high-intensity anaerobic exercise, followed by periods of rest for muscle recovery.
The intensity level of a HIIT workout should correspond to 80 percent of your maximum heart rate (MHR) or more. The goal is to alternate intense exercise with rest. The rest periods give your muscles a chance to partially recover so they can perform at a high intensity again. It’s a form of cardiovascular exercise that burns fat and improves your fitness level and health.
The benefits of HIIT include:
Fat loss — Studies show that HIIT can help you burn more calories than steady-state cardio. Although you burn calories during a high-intensity workout, you can burn more calories afterward due to the afterburn effect, the added calories your body uses to recover from intense exercise.
Increased fitness — Your VO2 max (a measure of fitness) will improve if you increase your intensity during high-intensity intervals. This means you can exercise longer or harder than before without tiring out. High-intensity interval training can also boost your anaerobic capacity, the ability to perform during intense exercise, thereby improving your exercise performance during short duration maximal exercise.
Breaking through plateaus – HIIT can help you break through sticking points and reach new levels of athletic performance, as it challenges your muscles and cardiovascular system differently. If your body is accustomed to doing moderate-intensity exercise and you add HIIT sessions, it can help you jumpstart fat loss if you’re trying to get leaner.
Improve cardiovascular health – Studies show that performing high-intensity interval training increases the number of capillaries in muscle tissue and improves their ability to transport oxygen throughout the body more efficiently than steady-state aerobic exercises like jogging or cycling. Both steady state and high-intensity exercise have cardiovascular benefits, but HIIT training has a slight edge for boosting cardiovascular health and fitness.
Improvements in insulin sensitivity – Studies show that high-intensity exercise improves insulin sensitivity, a measure of how well cells in your body respond to insulin. Better insulin sensitivity means that insulin can more efficiently move glucose from the blood into cells. This helps with blood glucose control and is a marker of better metabolic health. A study found that a single HIIT session improved insulin sensitivity and blood glucose control better than moderate-intensity exercise.
Can High-Intensity Exercise Reshape Your Metabolism?
Now, a new study finds that high-intensity exercise has documented benefits at the cellular level. Researchers asked eight untrained males to work out 3 times per week doing HIIT training. They cycled at greater than 90% of their maximum heart rate and rested for 2 minutes and repeated this cycle 5 times per workout.
Before the 5-week study started, researchers took tissue samples from the thighs of the participants and more samples at the end of the study. When they looked at the tissue samples using mass spectrometry, they found significant changes to the participants’ muscle cells Their muscle cells contained more proteins used to build mitochondria, the energy powerhouses of muscle cells. Their muscles also had a higher density of proteins that help muscle cells contract more efficiently.
The researchers also found that HIIT training modified key proteins involved in energy metabolism and muscle contractions. These modifications occur through a process called acetylation. Acetylation is the addition of an acetyl group to another molecule.
Why are these changes so beneficial? Mitochondria, mitochondrial proteins, and mitochondria function decline with age. High-intensity exercise is a way to preserve mitochondrial function and maintain stamina and a healthier metabolism as you age, and these benefits occur at the cellular level. HIIT training is good anti-aging medicine and the movements you do when you train help build functional strength and stamina to help you be your fittest and most functional.
HIIT Training is Adaptable to All Fitness Levels
Some people modify their workouts as they age to reduce their risk of injury. But HIIT training is adaptable to all ages and fitness levels. If you’re just starting your fitness journey, it’s best to start with shorter intervals of 20 seconds or less. As you build greater fitness, increase the intensity of your HIIT workouts by increasing the length of your intervals. You can also increase the number of intervals you perform as your fitness improves. Just as with strength training, you need to increase the challenge to keep making gains.
The Bottom Line
As you can see, a lot is going on at the cellular level when you do a HIIT workout. New proteins that build energy-producing mitochondria take place and your muscles adapt so that they contract more efficiently. Plus, acetylation at the cellular level changes how muscles function. So, every time you launch into a high-intensity workout, you’re improving your health and fitness.
If you’re just starting with HIIT training, take it slow at first. Here are some guidelines:
- Start with a warm-up. This should be about 5 to 10 minutes of low-intensity cardio, such as a walk or slow jog.
- You should feel like you’re working hard during each active interval. If you can easily talk while exercising, then you’re not pushing yourself hard enough. If you’re gasping for breath or struggling to catch your breath after an exercise session, then you’re probably doing it right!
- Don’t overdo it. If you’re new to this type of training, start slowly and build up gradually to more intense workouts. Work up to 20 minutes per workout at first until your body adjusts to high-intensity exercise; then increase your intensity over time as you get fitter. Start with two sessions per week, then increase it to a maximum of four once you’re used to it.
- Vary your routine so that it doesn’t become boring or repetitive and challenge yourself by increasing either duration or intensity according to what feels right for you at any time.
Enjoy the health and fitness benefits that HIIT training offers!
References:
- Ben Stocks, Anders Krogh Lemminger, Morten Hostrup, Alba Gonzalez-Franquesa, Jeppe Kjærgaard Larsen, Julia Prats Quesada, Martin Thomassen, Brian Tate Weinert, Jens Bangsbo, Atul Shahaji Deshmukh. High-intensity interval training remodels the proteome and acetylome of human skeletal muscle. eLife, 2022; 11 DOI: 10.7554/eLife.69802.
- “HIGH-INTENSITY INTERVAL TRAINING – LWW.” https://journals.lww.com/acsm-healthfitness/Fulltext/2014/09000/HIGH_INTENSITY_INTERVAL_TRAINING__A_Review_of.5.aspx.
- Journal of Clinical Endocrinology Metabolism. 99: 220-228. 2014.
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