Proven Benefits of Interval Training for All Ages and How HIIT Works

7 min read Chris Zibutis

Chris Zibutis
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Chris Zibutis
Head Running Coach - that one person on earth who loves interval runs 🥵

Have you tried interval running yet? Some people prefer interval training because it’s effective across ages and fitness levels. It can bring results faster than other training methods.

Read on to find out why interval training may be the best workout at any age. We’ll also show you how to get started with interval training and how often to do HIIT workouts.

What Is Interval Running?

You may have heard the term “HIIT” before. But what does HIIT stand for exactly? HIIT is short for high-intensity interval training.

It may sound a bit complicated, but it’s simple. Put simply, HIIT means switching between high-intensity and low-intensity exercise.

It’s a structured approach that uses intense fitness exercises to boost your endurance and strength and promote weight loss.

So, what does interval training usually involve when it comes to runners?

It’s all about alternating periods of low-intensity running (think jogging) with high-intensity running (think sprinting) in the same workout.

For example, you start with a warm-up, such as a light jog. Then you run for 30 seconds at 75% of your maximum speed. You then run 30 seconds at 25% of your speed, repeating these intervals several times during a workout.

The work-rest ratio, duration of each interval, number of reps, and total workout time depend on your fitness level and goals.

Why Some People Prefer Interval Training

Interval running comes with notable benefits over long-distance running at a consistent pace. Research validates the benefits of interval running, which is one of the reasons all types of runners embrace this form of training.

Another reason why some people prefer interval training is that it requires a smaller investment of time than other workouts. At the same time, it brings results faster.

HIIT is also fun and can add variety to your running workouts. And because it constantly challenges you to improve, it can become addictive. In a good way.

Who benefits most from interval training? It can benefit people of all ages. Whether you’re a beginner, intermediate, or seasoned runner, interval training can help you improve your fitness level.

Now let’s zoom in on the key benefits of interval training backed by science.

1. You’ll keep burning the calories for hours

Doing high-intensity interval training the right way will increase your caloric expenditure. HIIT burns more calories than continuous running at a constant pace.

The best part is that the greater caloric burn seen with HIIT occurs both during and after your workout. You’ll keep burning calories for up to two hours after a HIIT workout. In other words, HIIT can help you lose weight while building strength and endurance.

A 2014 study found that even 3 minutes of all-out HIIT per week increased muscles’ ability to use oxygen and boost cardiometabolic health. In the study, HIIT was integrated across multiple workouts for a total training time of 30 minutes per week.

2. People enjoy HIIT

A randomized controlled trial found that people enjoy HIIT more than exercising continuously. The researchers highlighted that HIIT is useful for those who’ve never tried it before.

HIIT can bring variation to your runs. At the same time, it can challenge you to push yourself harder.

3. HIIT boosts your endurance and running performance

Some people prefer high-intensity training simply because it’s an effective way to train. 

A 2018 study found that 6 sessions of sprint interval training improved both running endurance and power performance.

An earlier 2011 study highlighted that the quads, adductors, and hamstrings in the thighs, the gluteus in the hips, and gastrocnemius and soleus in the calves play a key role in acceleration and support during running. These include the muscles used in interval running. HIIT stimulates these muscles more than traditional running workouts and builds muscle fibers faster.

Meanwhile, another study found that HIIT improves cardiorespiratory performance. HIIT can carry performance improvements to your runs, rides, and other workouts.

4. Improved capacity to utilize oxygen      

A 2015 study published in Sports Medicine found that HIIT can increase VO2 max more than endurance training.

VO2 max is the maximum rate of oxygen your body can use during exercise. It’s a key factor in aerobic fitness. The greater your VO2 max, the more effectively your body can use oxygen to power up your muscles during running.

More recently, a 2020 meta-analysis found that HIIT also boosts the VO2 peak of older adults over 65 years more than traditional endurance training.

5. HIIT is time-wise more efficient than other exercises

Want to improve as a runner faster? High-intensity interval running is the way to go. A study published in the Journal of Physiology found that sedentary men who did sprint interval training three times a week for less than 12 minutes saw similar results to those who cycled for 40 to 60 minutes five times a week.

With HIIT, you can see better results than with low-intensity training, even if you train less every week.

6. Decreased risk factors for heart disease

A review article highlights that HIIT can have cardiovascular benefits. It can reduce your risk of coronary vascular disease and premature mortality in those with existing risk factors such as hypertension or diabetes.

7. It protects cells from aging

A 2017 Mayo Clinic study found that three months of HIIT reversed the age-related deterioration of muscle cells. What’s more, it triggered the growth of new muscles.

In younger participants, HIIT training boosted mitochondrial functioning. This process plays a key role in providing the body with energy.

The researchers noted that HIIT is more effective than strength training to slow down aging.

8. Increased insulin sensitivity

Other research shows that interval-walking training increases insulin sensitivity in diabetic patients. It also boosts fitness and helps with glycemic control.

Another study found that six weeks of HIIT improved insulin sensitivity and metabolic health. It also decreased age-related risk factors for metabolic disease.

9. Increased use of fat for energy

We’ve already seen that HIIT burns more calories and increases oxygen consumption compared to continuous intensity training. According to this study, HIIT also uses more fat for energy. The study involved both athletes and non-athletes and found that HIIT improves fat oxidation. This happens because HIIT boosts the oxidative capacity of mitochondria in cells.

How Do You Perform Interval Running?

HIIT is all about alternating intervals of high-intensity pace with low-intensity pace, with a warm-up and cool-down in between them. It’s good to start slow and work your way up to more demanding workouts gradually.

Which of the following scenarios best describes interval training?

  1. Walking, jogging, then running.
  2. Running at a continuous pace, walking, then running at a continuous pace again.
  3. Sprinting 15 seconds or 100 meters, resting, sprinting 20 seconds or 150 meters, resting, sprinting 25 seconds or 200 meters.

If you chose c, you already know how to perform interval running.

As someone new to interval running, you can start with 5-minute warm jogging to warm up. Then run for 30 seconds at 75% of your max effort before jogging again for 30 seconds. Repeat this 3 times twice per week. Every four weeks, you can start adding 1 more interval for each workout.

With a HIIT workout, before and after results will show after several weeks of training. After each workout, you’ll feel tired enough to know that your muscles are getting stronger.

HIIT Can Take Many Forms

You can adapt HIIT to many different forms of activity beyond running. For example, a V Shred HIIT Workout incorporates different exercises like burpees, high knees, and push-ups. Here are some more specific examples.

  • HIIT Swim Workout – Swim freestyle at maximum intensity for 30 seconds. Then swim breaststroke at 70% of your max intensity for 30 seconds. Rest 90 seconds. Repeat for a total of 20 minutes. You can also use the Stairmaster HIIT Rower for similar workouts.
  • CrossFit HIIT Workout – Each of the intervals in this workout lasts for 40 seconds, with 20 seconds of rest in between. Example exercises: burpees, dumbbell shoulder press, ring rows, box jump, dumbbell step-up, diamond sit-ups. Each set of intervals lasts 6 minutes. Repeat them without additional rest for a total of 30 minutes.
  • Continuous Interval – Continuous interval training combines continuous training with interval training. Here’s an example of alternating low intensity with high-intensity exercises: 10 push-ups, 45 seconds of burpees, 10 pull-ups, 45 seconds of pull-ups, 10 squats, 45 seconds of squat jumps. This completes a set. Aim for at least 15 minutes per workout or according to your fitness level.
  • HIIT Back Workout – Do each exercise for 30 seconds with 10 seconds of rest in between, for a total of 3 circuits. Exercises: Bent-over dumbbell row, reverse fly, renegade dumbbell row, bridge, superman.
  • HIIT Chest Workout – Perform each exercise for 30 seconds, resting 10 seconds in between exercises. Exercises: Push-ups, chest press, chest fly, plyometric push-up, dumbbell pullover. Repeat for 3 circuits.

How Frequently Should You Do Interval Training?

So, it is quite evident why some people prefer interval training. But, HIIT is not something you should do every day. You can do HIIT 2–3 times a week or according to your personalized training plan. You can also incorporate HIIT into a continuous training plan, doing it once a week or once every two weeks.

To get the most out of every HIIT workout you perform, it’s important to consider the disadvantages of HIIT as well.

  • Higher impact on your joints – High-intensity interval running can strain your knees, ankles, and hips if you overdo it. For this reason, it’s not ideal if you suffer from an untreated runner’s knee or another similar condition.
  • Your body needs time to adapt – Going from couch to HIIT can be demanding on your body. Muscles adapt faster than bones or joints. Taking it slowly and resting makes the adaptation easier.
  • May encourage overtraining – If you don’t follow a personalized plan, HIIT may lead to overtraining. It’s good to set limits early on.
  • HIIT vs. cardio – HIIT burns more calories and works your muscles harder than cardio. But it requires fine adjustments and determination, or you may plateau. If you’re out of shape, simple cardio can be easier to get started with.
  • Circuit training vs. HIIT – Circuit training combines six or more timed exercises with a rest period in between. HIIT differs from circuit training because it’s done at maximum effort. It’s more demanding. So again, if you’re just starting with training, circuit training may be easier.

Takeaway

Here are the key points to remember:

  • Interval training is a structured workout. It alternates between high-intensity and low-intensity exercise.
  • Some people prefer interval training because it burns more calories and improves fitness fast.
  • It can protect your cells against aging and decrease cardiovascular disease and diabetes risk factors.
  • Because it’s time-wise more efficient than traditional training, it can make you a better runner faster.
  • You can adapt HIIT to different activities, including swimming, cycling, and strength training.

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