The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Interval Training: Not Only for the Athlete

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Move more

Friday, Jul 15, 2016

High-intensity interval training (HIT/HIIT) is an effective method of training that yields improvements in exercise performance, fitness, and health. HIT is characterized by short, high-intensity work bouts, with lower intensity recovery phases that are repeated throughout one exercise session. This method allows the individual to perform more work than continuous, steady state exercise performed for the same amount of time. (Steady state exercise is characterized by performing the same intensity throughout the exercise session.) During HIT, the duration of the work bouts and the recovery time period, also known as the relief interval, vary depending on the training goal.  For example, those training for power may perform an all-out sprint for 15 second followed by a 1.5 min relief period. Most often this is referred to as a work to relief ratio and in the example above equates to a 1:6 ratio. Recovery intervals may either be passive (slow walk, stand, sit, etc.) or active (slower pace of the activity i.e. jogging following a run interval).  Table 1 illustrates typical work to relief ratios based on training goal.

Table 1. Work to relief ratios depending upon the training goal.

Now that we know what it is, let’s move on to the benefits of interval training, shall we? Peer-reviewed research has shown that interval training effectively increases both aerobic and anaerobic capacity. In fact, when compared to continuous, steady state exercise (1.5 hr/wk), high-intensity interval training (15 min/wk) resulted in similar aerobic performance effects (Gibala et al., 2006). This should be quite intriguing for individuals who do not engage in regular physical activity due to time constraints. However, keep in mind that a sedentary person should not start out with interval training. Rather, they should establish a good aerobic base first.

Aside from improvements in exercise performance, interval training has been shown to elicit favorable changes in body composition, specifically a decrease in fat mass coupled with an increase in lean body mass. For example, MacPherson, Hazell, Oliver, Paterson, and Lemon (2011) found that 6 weeks of sprint interval training performed at maximal speed (30 sec bouts accumulating 2 – 3 min/day, 3 times/week) resulted in a decreased fat mass of 12.4% (equivalent to 3.7 lb) in young adults. Furthermore, when compared to continuous, steady state exercise performed at a lower intensity (30 – 60 min/day), sprint interval training elicited similar benefits for the following variables: increase in lean body mass, decrease in 2000-m run time, and an increase VO2max, (cardiorespiratory fitness). 

You may be wondering, when it comes to fat loss, do men and women respond similarly to HIT? This has been a topic of great debate but most peer-reviewed studies demonstrate similar changes in body composition for both genders. For example, Hazell, Hamilton, Oliver, and Lemon. (2014) examined the effects of sprint interval training on fat loss in women. Following 6 weeks of HIT (4 – 6, 30-sec maximal effort sprints performed 3 times/week), the female participants decreased their fat mass by 8% (an average of 2.6 lb) as well as their waist circumference by 3.5%. This was accompanied by a 1.3% increase in lean body mass. The study also found favorable changes in cardiorespiratory fitness (↑8.7%) and peak running speed (↑4.8%). Comparing their findings to the findings of others, the authors concluded that high-intensity interval training elicits similar results in both men and women.

In conclusion, interval training is a time-efficient method of training that elicits similar exercise performance benefits as continuous, steady state exercise. Furthermore, interval training may lead to favorable changes in body composition. If you would like to know how to design interval training programs and/or are interested in more information on this topic, register for The Cooper Institute Interval Training course.

Gibala, M.J., Little, J.P., Van Essen, M., Wilkin, G.P., Burgomaster, K.A., Safdar, A., Raha, S., & Tarnopolsky, M.A., (2006). Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. Journal of Physiology, 575, 901 – 911.

Hazell, T.J., Hamilton, C.D., Oliver, D., & Lemon, P.W.R. (2014). Running sprint interval training induces fat loss in women. Applied Physiology, Nutrition, and Metabolism, 39, 944 – 950.

MacPhearson, R.E.K., Hazell, T.J., Oliver, D., Paterson, D.H., & Lemon, P.W.R. (2011). Run sprint interval training improves aerobic performance but not maximal cardiac output. Medicine and Science in Sports and Exercise, 43(1), 115 – 122.