In our last post, we explored a few of the many health benefits associated with regular physical activity and discussed two popular approaches to exercise that are worth considering: high–intensity interval training (HIIT) and moderate–intensity continuous training (MICT). Since HIIT has now become something of a buzzword and MICT is essentially the type of exercise most people do—often without knowing its technical name—it’s likely that there are some unanswered questions out there regarding how to go about these types of training and what’s right for you. In response, in this post we’ll answer some of the most frequently asked questions about HIIT and MICT.

Q: What is aerobic exercise?

A: Also known as endurance or cardiovascular exercise, aerobic exercise is any form of physical activity in which oxygen is heavily involved. This is most clearly evident by noticing an increase in your heart rate and by breathing more deeply during these activities, which are signs that your body is maximizing the amount of oxygen in the blood to help you use it more efficiently. HIIT and MICT are both considered forms of aerobic exercise, while other examples include walking, jogging, swimming, biking, jumping rope, and playing basketball. Over time, performing aerobic exercises can significantly improve the function and performance of the heart, lungs, and circulatory system, leading to various benefits, such as better heart health, sleep patterns, weight regulation, and metabolism.

Q: How do I calculate my resting and optimal exercise heart rate?

A: Since all types of aerobic exercise increase the heart rate, it’s important to understand how far you should be pushing yourself to make sure getting the most out of your workouts but staying safe while doing so. Your resting heart rate is the number of times your heart beats per minute (bpm) when you’re at rest, and it’s an indicator of your physical fitness level. Many fitness trackers and smartwatches measure track your heart rate automatically, but if you don’t have one of these devices, you can measure your resting heart rate manually by taking your pulse at your wrist or (below the base of your thumb) over 60 seconds (or for 6 seconds and multiplying by 10, 15 seconds and multiplying by 4, etc.). An average adult heart rate is 60–100 beats bpm, with the lower end indicating good overall fitness and the higher end generally associated with health problems like metabolic syndrome.

The next step is to calculate your maximum heart rate, which can be done by using one of several formulas, the easiest of which is subtracting your age from 220. Once you know your maximum heart rate, you can choose from aerobic activities that range from very light (under 57% of maximum heart rate) to maximal (96–100% of maximum heart rate). If you’re new to exercise, it’s best to start in the low range and gradually work your way up until you find your target, or optimal heart rate zone.

Q: What are some examples of HIIT programs?

A: If you’re just getting started with HIIT, here are a few examples of single–exercise workouts that are great for introducing you to this type of training:

• Bike: pedal on a bike as hard and fast as possible for 30 seconds, then pedal at a slow, easy pace for 2–4 minutes; repeat this pattern for 15–30 minutes
• Jog/run: after jogging to warm up, sprint as fast as you can for 15 seconds, then walk or jog at a slow pace for 1–2minutes; repeat this pattern for 10–20 minutes
• Squats: Perform squat jumps as quickly as possible for 30–90 seconds, then stand or walk for 30–90 seconds; repeat this pattern for 10–20 minutes

You can also find a multitude of free HIIT programs on YouTube and other fitness websites. One great website for free videos is Fitness Blender.

Q: What are some examples of MICT programs?

A: Remember that MICT is performed at a moderate intensity but for longer periods of time than HIIT (MICT exercises are typically completed at 55–75% of one’s maximum heart rate, while HIIT hits at around 80–85% of maximum heart rate). Following our last examples, you can modify a biking or jogging HIIT workout and make it an MICT workout instead by reducing the intensity, eliminating the rest periods, and extending the duration. In other words, a bike ride at a moderate pace for 20–40 minutes or a jog at a moderate pace for 20–30 minutes.

Other examples of MICT activities include any of the following, performed at a moderate pace for at least 20 minutes:

• Swimming
• Brisk walking
• Playing a pick–up game or practicing basketball, soccer, or football
• Hiking
• Kayaking

Q: Is HIIT safe for older adults?

A: In most cases, yes, but this depends heavily on your current fitness level. One of the most attractive features of HIIT workouts is that there are practically endless modifications that can be made to the types of exercises, durations, and rest periods to suit your activity level. If you’re interested in HIIT but aren’t already physically active, we strongly recommend consulting a doctor or a physical therapist, who can give you a fitness test and provide you with guidance to get you started.

Q: How can I start a HIIT or MICT program?

A: As we mentioned above, physically active individuals can get started on their own, but if you’re new to moderate– or vigorous–intensity exercise, talk with your doctor or physical therapist first to clear you for activity and help move on the right track.

In our next blog, we’ll look at the role that various diets can also play in reducing the risk for various health conditions.