By Dr Mike Bracko (Dr Bracko will be here on 24th September to teach HIIT Workshop, see more info here)
The question is, which variable, or variables, are the most important for getting maximum benefit from the HIIT training. Is it the work or is it the rest that is most important when designing HIIT protocols for clients? Training protocols used in research studies have a multitude of work-to-rest lengths and with varying benefits, ie: burn more calories, improve V02, reduce skin folds. This article will explore the different work-to-rest ratios.
- List the nine variables that can be modified in an high intensity interval training work-out.
- Review the HIIT protocols that resulted in higher V02 and anaerobic capacity.
- Review the HIIT protocols that resulted in high caloric expenditure and fat loss.
HIIT to Increase V02/Anaerobic Capacity
Tabata., et al., (1996) used 20 seconds of all out exercise, followed by 10 seconds of rest, repeated for 4-minutes. He discovered his four-minute improved anaerobic capacity by 28% and their V02max by 7 ml/kg/min.
For clients wanting to improve V02 and anaerobic capacity, perhaps the highly motivated clients, the Tabata training is an excellent program. It is high intensity with clients working as hard as they can, only 4-minutes, and remarkable benefits considering volume of training.
Gunnarsson and Bangsbo (2012) used a very different work-to-rest ratio. They call it the “10-20-30” protocol. Each interval consisted of the following: running for 30 seconds at 30% of maximum intensity, running for 20 seconds at 60% of maximum intensity, and running for 10 seconds at 90–100% of maximum intensity, repeated for 5 minutes. There was a two-minute rest between the interval protocol, and this was repeated three or four times.
The major findings of the “10-20-30” group: decreased 1500 meter running time 21.00 seconds, five-kilometer running time decreased 48.00 seconds, V02max improved 4%, total cholesterol and LDL cholesterol were lower, and systolic blood pressure was lower. This “10-20-30” protocol is for the highly motivated clients in our gym or class.
Whyte, Gill, Cathcart (2010) used ten overweight/obese sedentary men and had them perform two weeks, six sessions, of four to six, 30 second Wingate sprints with 4.5 minutes of recovery. The results showed VO2max and Wingate power increased. In addition, insulin sensitivity and resting fat oxidation rate were higher (24 hours post-work-out), systolic blood pressure and resting carbohydrate oxidation were lower (24 hours post-work-out), and waist and hip circumferences decreased.
Gillen, et al., 2014 used sedentary overweight and obese males and a female. They performed three, 20 second ‘‘all-out’’ cycle sprints with a two-minute recovery between intervals. They exercised three days per week for six weeks and had eighteen training sessions. The results show that peak oxygen uptake increased by 12%, resting blood pressure decreased by 7%. Remarkable results for 60-seconds of “all out” work/training session.
HIIT to Burn Fat/Calories
Tabata et al. (1996) did not calculate calories burned in his training protocol, but Michele Olson (2013) did. She had her subjects perform a Tabata routine using jump squats. Olson (2013) found the subjects burned 13.5 kcals/min for a total of 54 kcals in the 4-minute protocol and 81 kcals for 30-minutes after the training. The subjects burned 135 calories in total.
Higgins, et al., (2016) investigated the effects of sprint interval training (cycling) (SIT) and moderate-intensity continuous cycle training (MICT) on body composition and aerobic capacity. The training lasted six weeks. The subjects were inactive overweight/obese women. Sprint interval training was performed in a group-exercise cycling classes, and included 3 sessions/week of a 20-minute work-out consisting of 30-seconds “all-out” cycling sprints followed by 4 minutes of active recovery (2.5 – 3.5 minutes work with 16-28 minutes of rest). Moderate-intensity continuous training was completed by cycling for 20 – 30 minutes at 60%-70% heart rate reserve to expend a similar amount of energy during training as was done with the SIT group.
Without significant changes in body mass, the SIT group had greater relative decreases in total fat mass and android fat mass. Aerobic capacity increased in both groups, but the relative increase was 2-fold greater in SIT. The authors conclude that SIT cycling reduces fat mass and increases aerobic capacity more than continuous MICT.
Tremblay, Simoneau, and Bouchard (1994) compared MICT and HIIT on fat loss and muscle metabolism. The MICT group did 20 weeks of endurance training on a cycle ergometer, four then five times per week, for 30 to 45 minutes, at an intensity of 60% – 85% of heart rate reserve. The HIIT protocol consisted of 19 short interval sessions (10 – 15 work bouts of 15 – 30 seconds) and 16 long intervals (4 – 5 work bouts for 60 – 90 seconds). The intensity of the training was 60% – 70% of the maximal work output. Recovery was when the heart rate lowered to 120-130 beats/minute. The results show total calories burned for the MICT group was 28,757.04 and the HIIT group burned 13,829.17, a difference of 14,927.87. The HIIT group decreased their sum of six skinfolds nine-fold less than the endurance group. The HIIT group also had a significant increase in enzymes promoting fat being used as energy for muscle contraction. If you want to decrease skin folds, stick to HIIT at 60% – 70% of the maximal work.
Hazell, et al., (2014) had fifteen recreationally active women perform six weeks of sprint interval training. The subjects did 4 to 6, 30-second maximal sprints on treadmill with four minutes of rest between sprints, three times/week. The results show that the sprint interval training decreased body fat by 8% and waist circumference by 3.5%. There were increases in fat-free mass of 1.3%, maximal oxygen consumption of 8.7%, and peak running speed of 4.8%. The authors conclude their training protocol is a time-efficient mode of training for decreasing body fat, increasing aerobic capacity, increasing peak running speed, and increasing fat-free mass in healthy young women.
Shepard, et al., (2015) performed their training protocols with a group cycling HIIT protocol and compared it to group cycling MICT. The HIIT group performed repeat cycling sprints, 15–60 seconds, 90% HRmax with 45 – 120 seconds of active recovery. Each session was 18 – 25 minutes with three sessions/week. The MICT group performed continuous cycling at 70% HRmax for 30–45 minutes/session with five sessions per week. Both groups trained for ten weeks.
The HIIT group had better attendance. The average weekly training for HIIT was 55 minutes and MICT was 128 minutes. Both groups improved or reduced on the following variables: V02max, insulin sensitivity, feelings of energy (subjective vitality), feelings of health perception, and reduced fat mass. The MICT also reduced systolic blood pressure. The researchers conclude the HIIT group had good results, reduced training time, and greater adherence.
Zhang, et al., (2017) compared the effect of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on reducing abdominal visceral fat in obese young women. Forty-three participants did either HIIT (n = 15), MICT (n = 15), or no training (CON, n = 13) for 12 weeks.
MICT group participants trained on a cycle ergometer at an intensity of 60% of V̇O2max until they achieved 300 kJ of work. The pedal frequency was 60 rpm during each training session. HIIT group participants repeated 4-minute cycling exercise bouts at an intensity of 90% of V̇O2max, followed by a 3-minute passive recovery until 300 kJ of work was achieved.
The average work-out time for the HIIT group was 33.85-minutes/week and the MICT was 62.73-minutes/week. Results show the HIIT and MICT had similar results for fat reduction. The authors conclude the obvious choice for reducing fat content is HIIT considering the same results were achieved in half the time.
Heydari, Freund, and Boutcher (2012) investigated the effect of high intensity interval exercise (HIIE) on fat reduction on young overweight males. There was a HIIE and a control group. The HIIE group did 8-seconds of exercise at 80 – 90% of peak heart rate at a cadence between 120 and 130 rpm on a cycle ergometer, followed by 12-seconds of recovery at 40 rpm. They performed this work-to-rest ratio for 20-minutes, three times/week for 12 weeks.
These are the results for the HIIE group: aerobic power improved 15%, weight loss = 3.3 pounds, total fat mass decreased by 4.4 pounds, abdominal fat decreased by 0.22 pounds, trunk fat decreased by 3.3 pounds, visceral fat decreased by 17%, waist circumference decreased by week six 3.5 cm, fat free mass increased 0.88 pounds for the legs, and fat free mass increased 1.5 pounds for the trunk. The researchers conclude that exercise prescriptions with minimal work, but producing fat reduction are the key to improving exercise compliance.
Many clients have different goals for their exercise program. Some want to improve physical fitness to feel better. Some clients want to burn the maximum number of calories. And other clients exercise to reduce their fat content. It appears there are HIIT protocols for all three.
V02max is the gold standard of measuring fitness. The Tabata, et al. (1996) training had very good improvements in V02 (and anaerobic capacity which is another good measure of fitness) of 7 ml/kg/min with only 4 minutes of training per session. Gunnarsson and Bangsbo (2012) with their “10-20-30” protocol found that subjects improved V02max 4%. Other measures of fitness which are more relatable were that the subjects decreased their 1500- meter running time by 21.00-seconds and their five-kilometer running time decreased by 48.00-seconds.
Olson (2013) found that subjects who did a Tabata work-out burned a total of 54 kcals during the work-out, and 81 kcals for 30-minutes after the training, for a total of 135 kcals. Tremblay, Simoneau, and Bouchard (1994) found that subjects who did a HIIT protocol at 60% – 70% of the maximal work output burned a total of 13,829.17 in 15-weeks.
Many clients are interested in reducing their fat content. Many HIIT protocols had good results for fat loss. Higgins, et al., (2016) used inactive overweight/obese women as subjects and found that a protocol of “all out” sprint interval cycling reduced total fat mass and android fat mass more than subjects who used MICT. Tremblay, Simoneau, and Bouchard (1994) found that a group who used HIIT at an intensity of 60% – 85% of heart rate reserve reduced their sum of six skinfolds nine-fold less than the MICT group. Hazell, et al., (2014) had subjects perform 4 to 6, 30-second maximal sprints on treadmill with four minutes of rest between sprints, three times/week. The subjects decreased body fat by 8% and waist circumference by 3.5%. Heydari, Freund, and Boutcher (2012) investigated a protocol of high intensity interval exercise (HIIE) of 8-second cycle sprints with 12-seconds rest for 20-minutes. Compared to a control group, the HIIE group lost 3.3 pounds, total fat mass decreased by 4.4 pounds, trunk fat decreased by 3.3 pounds, and visceral fat decreased by 17%.
Hazell, T.J. et al., 2014. Running sprint interval training induces fat loss in women. Applied Physiology, Nutrition, and Metabolism. 39(8), 944-50.
Higgins, S., et al., (2016) Sprint interval and moderate-intensity cycling training differentially affect adiposity and aerobic capacity in overweight young-adult women. Applied Physiology Nutrition and Metabolism. 41(11):1177-1183.
Heydari, M., Freund, J., and Boutcher, S.H., (2012), The effect of high-intensity intermittent exercise on body composition of overweight young males, Journal of Obesity. 2012;2012:480467. doi: 10.1155/2012/480467.
Gillen, et al., (2014) Three minutes of all-out intermittent exercise per week increases skeletal muscle oxidative capacity and improves cardiometabolic health, November 3, http://dx.doi.org/10.1371/journal.pone.0111489
Gunnarsson, T.P. and Bangsbo, J. (2012). The 10-20-30 training concept improves performance and health profile in moderately trained runners. Journal of Applied of Physiology, 113(1):16-24.
Shepard, S. et al., (2015) Low-volume high-intensity interval training in a gym setting improves cardio-metabolic and psychological health, DOI: 10.1371/journal.pone.0139056
Olson, M, (2013), Tabata Interval Exercise: Energy Expenditure and Post-Exercise Responses
American College of Sports Medicine Annual meeting, May 2013.
Tabata, I., et al., (1996). Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Medicine and Science in Sports and Exercise, 28 (10): 1327–1330.
Tremblay, A. Simoneau, J.A. and Bouchard, C. (1994). Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism 43(7): 814–818.
Whyte, L.J., Gill, J.M., and Cathcart, A.J. 2010. Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men. Metabolism, 59(10):1421-8.
Zhang, H., et al., (2017) Comparable Effects of High-Intensity Interval Training and Prolonged Continuous Exercise Training on Abdominal Visceral Fat Reduction in Obese Young Women. Journal of Diabetes Research. 2017;2017:5071740. doi: 10.1155/2017/5071740. Epub 2017 Jan 1.