How to Get the Best Bang from Exercise for the Investment in Time
By Dr. David M. Brady and Danielle Moyer
Before performing any of the following physical exercises, please consult with your doctor about whether this is appropriate for you.
Some of us have heard the saying “sitting is the new smoking.” Such a bold statement hints that our sedentary lifestyles of sitting at our computer, taking Zoom calls, and watching television have enormous impacts on our health. But how? We know that exercise can help with weight loss, but it can also help to prevent chronic diseases such as Parkinson’s and Alzheimer’s, improve your mood, boost your immunity, improve cardiovascular function, and promote a healthy gut and microbiome.1-5
So, if exercise is so good for us… Why don’t we do it?
One word: Time.
Trying to find time for work, family, self-care, healthy eating, errands, and being a normal human can be exhausting some days! If one isn’t familiar with exercise, it seems like a daunting, frustrating, and time-consuming task.
The World Health Organization recommends that adults engage in moderate-intensity exercise for 150 minutes per week to maintain proper cardiovascular health.6 But let’s face it. Most of us need 150 more minutes of sleep.
Unsurprisingly, the number of adults that remain sedentary is high. This can increase the risk of mortality, cardiovascular disease, cancer, and diabetes. In fact, one out of five adults are physically inactive across the globe.6
There is some good news. Since so many people face this issue, in the last two decades we found a solution: High-Intensity Interval Training (HIIT).
HIIT consists of short, intense exercises that last around 10 to 30 minutes. It is designed to alternate consistently between two modes: an intense “work period” and a “recovery period”.
The intense work period should be performed at 80% to 95% of a person’s estimated maximal heart rate. The recovery period is performed at 40% to 50% the person’s estimated maximal heart rate.7-8 Estimating your maximal heart rate will vary person-to-person depending upon your level of fitness. The objective during the intense work period is to feel your heart pumping such that you would have trouble carrying on a normal conversation. The active recovery period is when you are able to speak full sentences, but would have trouble singing.8
*Note: To make your HIIT workouts really work efficiently and maximally, begin to monitor your heart rate variance during your “work” and “recovery” periods. This can be done via a heart rate monitor on your chest or wrist. For example, one person may only need to run at speed 4 on a treadmill to get their heart rate in the 80% to 95% zone, whereas someone else may need to go to speed 7. It is individualized to you. Monitoring your heart rate variance during HIIT gives your workout even more intent and purpose.
HIIT is a class of exercise first largely used by elite athletes.9 Now, even the AARP dubs HIIT as the ‘miracle’ workout that everyone should be doing.10 HIIT is not only designed to be short and time-effective, but studies show that HIIT may result in even more health benefits than moderate intensity “aerobic” exercises.9-12 Additionally, it is found to be enjoyable, safe and tolerable for most adults.12
One of the best benefits of HIIT is its effect on heart-rate variability (HRV).7 Heart rate variance is a way to evaluate your cardiovascular health non-invasively. It has been shown that people who have high HRV have greater cardiovascular fitness and are more resilient to stress, and this can improve with time the more one works out.13 It’s a good idea to track your heart rate variance when exercising to track your performance, such as using a heart rate monitor chest strap. HIIT has been shown to be superior to typical moderate exercises in improving HRV in physically inactive adults.7
Other benefits of HIIT include…6-12,14-16
- Improves blood pressure
- Improves cardiovascular health
- Improves insulin sensitivity
- Burns more calories than traditional workouts in same amount of time
- Helps burn fat
- Increases muscle mass for non-active individuals
- Increases metabolism for hours after exercising
- Improves cellular function
Here are some quick guidelines for HIIT:
1) How long should each HIIT workout be?
HIIT is designed to consistently alternate between work and recovery periods, totaling anywhere from 10 to 30 minutes, depending on your goals and exertion levels.
The nice part about HIIT is you can easily modify your preferred difficulty level and workout time. Experiment with different time durations and repetitions to find what is best for you. Here are two methods to get your started:
The 4x4 method7
True to its name, it is called the 4x4 method because it involves 4 rounds of burst high intensity exercise for 4 minutes, with 3 minutes of active recovery in-between each. The workout is bookended by 3-minute moderate intensity warm-up and cool-off periods, bringing us to a grand total of about 30 minutes.7
The Wingate Method7
This method includes shorter, higher intensity bursts of energy. After warming up with 3 minutes of moderate intensity, one would work for 30 seconds at vigorous intensity, followed by a recovery period for 2-5 minutes. Repeat 6 to 8 times.7
After reading those, you may be tempted to start out with a beginner workout. Try the 10-minute model HIIT workout one time a week. This would include a 3-minute moderate intensity warm up, a work period of 20 seconds and a moderate recovery period for 1-2 minutes. Repeat those repetitions two more times.10
2) How many times a week do I have to do HIIT workouts?
Again, this is up to you. You can begin with one time a week for 10 minutes, and slowly increase to two to three times a week for 30 minutes. Because it is more exhausting than endurance workouts, such as going for a 30-minute light jog, it is recommended to spread the HIIT workouts throughout the week to optimize longer recovery periods (at least 24 hours between sessions).8
3) What exercises can be done with the HIIT model?
Another excellent thing about HIIT is you can tweak aerobic exercises you do now to match the HIIT model. No fancy machines are necessary - just a timer and commitment to ratchet-up the intensity of the workout to achieve the desired maximal heart rate for the intended duration!
This includes running, walking, jogging, rowing, biking, swimming, cycling, elliptical training, stair-climbing, dancing, kickboxing, spinning, hiking, or any other exercises (burpees, jump squats) that get your heart pumping. However, probably the most often used exercise to accomplish high intensity burst training is sprinting on a treadmill, followed by walking during the recovery period, and then repeating this pattern the desired number of times.
As with any exercise, there are potential risks of injuries, so speak with your doctor before starting any new routine. If you are low on time, high-intensity interval training (HIIT) can be considered the best exercise for time management and to attain the best “bang for your buck”! Start slowly and build it up through time. When it comes to HIIT, every second counts!
- Cheng S-T. Cognitive Reserve and the Prevention of Dementia: the Role of Physical and Cognitive Activities. Curr Psychiatry Rep. 2016;18(9):85. doi:10.1007/s11920-016-0721-2
- Aylett E, Small N, Bower P. Exercise in the treatment of clinical anxiety in general practice - a systematic review and meta-analysis. BMC Health Serv Res. 2018;18(1):559. doi:10.1186/s12913-018-3313-5
- Healthy Mind, Healthy Body: Benefits of Exercise. Harvard Medical School website. https://hms.harvard.edu/sites/default/files/assets/Sites/Longwood_Seminars/Exercise3.14.pdf. Updated March 13, 2014. Accessed January 8, 2021.
- Warburton DER, Nicol CW, Bredin SSD. Health benefits of physical activity: the evidence. CMAJ. 2006;174(6):801-809. doi:10.1503/cmaj.051351
- Johannesson E, Simrén M, Strid H, Bajor A, Sadik R. Physical activity improves symptoms in irritable bowel syndrome: a randomized controlled trial. Am J Gastroenterol. 2011;106(5):915-922. doi:10.1038/ajg.2010.480
- Alansare A, Alford K, Lee S, Church T, Jung HC. The Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Heart Rate Variability in Physically Inactive Adults. Int J Environ Res Public Health. 2018;15(7). doi:10.3390/ijerph15071508
- Ito S. High-intensity interval training for health benefits and care of cardiac diseases - The key to an efficient exercise protocol. World J Cardiol. 2019;11(7):171-188. doi:10.4330/wjc.v11.i7.171
- ACSM Information on… High Intensity Interval Training. American College of Sports Medicine website. https://www.acsm.org/docs/default-source/files-for-resource-library/high-intensity-interval-training.pdf?sfvrsn=b0f72be6_2. Accessed on January 8, 2021.
- Mekari S, Earle M, Martins R, et al. Effect of High Intensity Interval Training Compared to Continuous Training on Cognitive Performance in Young Healthy Adults: A Pilot Study. Brain Sci. 2020;10(2). doi:10.3390/brainsci10020081
- Furchgott R. High-Intensity Interval Training: Why It Just May Be a ‘Miracle’ Workout. AARP website. https://www.aarp.org/health/healthy-living/info-2018/high-intensity-interval-training-workout/. Published November 7, 2018. Accessed January 8, 2021
- Kong Z, Fan X, Sun S, Song L, Shi Q, Nie J. Comparison of High-Intensity Interval Training and Moderate-to-Vigorous Continuous Training for Cardiometabolic Health and Exercise Enjoyment in Obese Young Women: A Randomized Controlled Trial. PLoS One. 2016;11(7). doi:10.1371/journal.pone.0158589
- Garber CE, Blissmer B, Deschenes MR, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334-1359. doi:10.1249/MSS.0b013e318213fefb
- Campos M. Heart rate variability: A new way to Track well-being. Harvard Health Publishing: Harvard Medical School website. https://www.health.harvard.edu/blog/heart-rate-variability-new-way-track-well-2017112212789. Published November 22, 2017. Accessed January 8, 2021.
- Wewege M, van den Berg R, Ward RE, Keech A. The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obes Rev. 2017;18(6):635-646. doi:10.1111/obr.12532
- Damas F, Phillips S, Vechin FC, Ugrinowitsch C. A review of resistance training-induced changes in skeletal muscle protein synthesis and their contribution to hypertrophy. Sports Med. 2015;45(6):801-807. doi:10.1007/s40279-015-0320-0
- Falcone PH, Tai C-Y, Carson LR, et al. Caloric expenditure of aerobic, resistance, or combined high-intensity interval training using a hydraulic resistance system in healthy men. J Strength Cond Res. 2015;29(3):779-785. doi:10.1519/JSC.0000000000000661
- David Brady