Is Interval Training Appropriate For A Sedentary, Overweight Population?

As always happens when something is incredibly popular, there has been backlash against sprint interval training. Some sports scientists have argued that even though sprint training may produce greater health and weight loss benefits, it is too physically challenging for non-athletic populations.

In one recent article, a research group from Australia and the UK made the case that people who are sedentary and overweight should not be encouraged to try interval training. They worry that interval training is too difficult and may trigger feelings of “incompetence, lower self esteem, and failure.” Other reasons offered to avoid interval training include the following:

• It requires high levels of motivation and confidence.
• It is physically challenging and likely to evoke negative feelings; meaning people won’t stick with it.
• It is too complex, requiring a high degree of self-regulation for which novice exercisers don’t have the experience to navigate.
• It is not time efficient when you include warm up and cool down.

Although the authors make some interesting points that can guide us in developing top-notch programs, their argument misses the boat. Interval training is one of the most researched forms of exercise and it has been found to be effective and appropriate for a vast range of populations: Whether you are elderly, overweight, obese, diabetic, a kid, an athlete, have arthritis, have high blood pressure, are recovering from a heart attack or cancer, or have a spinal cord injury, there is an interval protocol that can benefit you.

This article will refute the arguments made against interval training and attempt to convince you to give interval training a try. Before we get into the nitty gritty, let’s clarify what interval training is:

Classical sprint training (SIT) uses maximal “all-out” intervals interspersed with full rest periods. An example is the Wingate protocol, which is 4 to 6 bouts of 30-second maximal sprints performed on a bike or track.

Second, there is high-intensity interval training (HIT) that requires you to do intense but short exercise interspersed with rest. Work bouts are less intense (less difficult) than with sprint training and the intensity of the exercise is relative to each individual. What is ideal for a fit trainee will be different from that which a novice should do.

Is Interval Training Enjoyable?

The first question to answer is if interval training is enjoyable. Why does enjoyment matter?

It is a predictor of exercise adherence. If people find some gratification or pleasure in the type of exercise they do, they are more likely to keep doing, which as everyone knows, is key for getting results.

The argument against interval training states that as exercise intensity increases, pleasure and enjoyment decrease. This is true for steady-state aerobic exercise, with intensities above the ventilatory threshold being rated as most unpleasant. However, this evidence does not apply to interval training, which intersperses rest with intense work bouts and is thought to improve the enjoyment of exercise.

In one direct comparison of steady-state aerobic exercise with intervals, there was no difference in enjoyment between the two types of exercise.

In other studies, interval training has been reported to be more enjoyable than steady-state exercise. For example, in a population that was recovering from spinal cord injury (which would presume low exercise tolerance), both HIT and SIT were found to be more enjoyable than 25 minutes of steady-state exercise.

Does Interval Training Produce Better Results?

Naturally, a key factor in promoting adherence and motivation to exercise is if it produces results. Studies show that although the typical recommendation to perform 30 minutes of aerobic exercise 5 times a week is insufficient for fat loss in the absence of a dietary intervention, interval training consistently produces fat loss and improves metabolic function.

A 2008 study found that in a population of sedentary women, 20 minutes of stationary bike intervals produced an average 11.2 percent decrease in fat mass (-2.5 kg) compared to an small increase (0.44 kg) of fat in a group that did 40 minutes of steady-state aerobic exercise.

A 2016 study of obese, sedentary women found that sprint training (using the Wingate protocol) produced greater loss of total fat (-3.6 percent) compared to a group that did 30 minutes of steady-state exercise (-0.6 percent). The interval group also lost significantly more belly fat (-6.6 percent compared to no change in the aerobic group).

Other observed health benefits of interval training include the following:

• Greater lean muscle mass due to increased protein synthesis
• Higher rates of fat burning
• Increased insulin sensitivity and lower insulin levels
• Lower blood pressure and better arterial function
• Decreased chronic inflammation

Will People Do It?

Unfortunately, a big problem that trainers and scientists are dealing with is the fact that when people are on their own (not enrolled in an exercise study or not working out with a trainer), adherence rates are very low. This doesn’t seem to be an issue of interval training vs aerobic exercise as much as one of inertia and a tendency towards sedentariness in the human population.

That said, in randomized trials, adherence to interval training is equal to or greater than that observed with steady-state exercise. A 2015 free-living study that assessed adherence based on digital exercise trackers found that sedentary, pre-diabetics had greater adherence to an interval training protocol (subjects completed 89 percent of workouts) compared to a steady-state workout (71 percent adherence). Although it did include lab tests and some behavioral feedback from coaches, the free-living model is a better model of how people react to different exercise programs than a study in which all workouts are performed in a lab setting with staff supervision.

A series of other studies have shown similar or greater adherence and enjoyment with moderate to high-intensity interval protocols (work bouts ranging from 1 to 3 minutes) compared to steady-state training, suggesting that people will engage in interval training at least as eagerly as they will in simpler continuous protocols.

Does Interval Training Make People Feel Incompetent?

Obviously, no one likes to feel incompetent or do something that lowers self-esteem. However, there is no scientific evidence to suggest that interval training has this effect.

Rather, interval protocols are typically designed to logically progress participants by increasing work bouts to ensure a sense of accomplishment and mastery, along with physiological adaptations. This follows what we know about how people develop self-confidence by successfully performing a specific task.

Additionally, the motivation that is provided by the positive health and body composition improvements will reinforce a positive self-esteem and feeling of capability. For example, interval training has been shown to improve motivation, particularly with regard to appearance and maintenance of body mass, as well as quality of life scores in elderly, sedentary people.

Further, a 6-week trial found that interval training led to improvement in the perception of health and mood of sedentary women (30–65 years) at risk for metabolic syndrome.

Of course, results take time. Regardless of the type of training, a big obstacle facing overweight and sedentary populations is the negative feelings they have about moving their bodies and being physically active, especially in a public setting.

Is Interval Training Too Complex For Non-Athletes?

Although it is true that following a workout protocol that prescribes intensity based on percentages of oxygen uptake is too complex for most people, there are a number of effective interval workouts with simpler intensity prescriptions. Using a rating of perceived exertion model is effective for individuals to monitor intensity. For example, even novice trainees can be taught what it means to work at an 8 or 9 (equaling “very hard”) on a 10-point scale.

A key point here is that for almost any exercise protocol to be effective for beginners, some coaching is necessary. We need a better public health approach for combating obesity and the sedentary culture than simply telling people to “eat less, and move more.”

It’s unreasonable to expect sedentary individuals who have never exercised before to know how to train with weights, do intervals, or perform a heart-rate based aerobic exercise protocol. A devil’s advocate may suggest that this population can start without any coaching by going out for a walk.

Certainly, this is a good start and we know from anecdotal reports that novices can start with what they know (walking, biking, jogging) and take it from there, incorporating interval-based training along with a wide range of exercise protocols as they improve fitness. However, we could reach a greater population, results would be better, and adherence greater if people had skilled exercise coaching from the start.

How To Get Started?

Where should you start if you are sedentary and/or overweight and want to try interval training?

Here are a few protocols that have been tested in recent studies:

These workouts can be done on a stationary bike, at a track, on a walking path, on a treadmill, or other piece of exercise equipment such as an elliptical. Perform them 2 to 4 times a week.

#1: 60-Second Interval/60-Second Rest

Start with 4 work bouts of 60 seconds at a moderately hard pace (6 or 7 on a 10-point rating of perceived exertion scale (RPE)). Rest periods are active, at an easy pace for 1 minute. Each workout, increase the number of intervals you perform until you reach 10.

#2: 8-Second Interval/12-Second Rest

Start with 5 minutes total in which you alternate between 8-seconds of all-out effort followed by 12-seconds active rest. Increase your workout time by 5 minutes each week until you reach a total of 20 minutes of intervals. This workout is best done on a bike or elliptical so that you can easily monitor the time.

#3: 30-20-10 Intervals

This workout breaks each minute into 3 segments: For 30 seconds you work at an easy pace. For the next 20 seconds you work at a moderate pace (5 or 6 on a 10-point RPE scale). For the last 10 seconds you go all-out (9 or 10 on a RPE scale). Start by repeating for 5 minutes. Each week, add 5 minutes to your total workout until you reach 20 minutes.