Have They Found the Perfect Interval Formula?

In the fitness world, buzzwords come and go almost monthly. One that seems to have some real staying power, though, is high intensity interval training, or HIIT. Although it’s not really a new idea, HIIT has really gained ground in the past few years with the rise of standardized forms like Crossfit, Tabata and the Little method. Even with these programs, though, a universal formula for an effective HIIT workout has been sorely lacking.

A group of Danish researchers set out in 2012 to define the perfect formula for HIIT and their work produced some intriguing results worth considering.

The 10-20-30 Study

At the beginning of their research, the team, led by Dr. Thomas Gunnarsson experimented with different ratios that are already at use in other HIIT methods.

Starting with 30-second sprinting bouts, which is a common approach, they found that, although this produced powerful results in their subjects, it’s also a very demanding. Eventually, through trial-and-error, the team fell on 10-second intervals.

It’s not really surprising that the 10-second sprints produced benefits but the exact depth of those improvements has caught many experts off-guard.

Over the course of the 7-week study, veteran 5K runners cut a full minute off their time and 1500-meter runners reduced their time by an average of 23-seconds. And these reductions all happened while slicing their weekly mileage by half. As an added selling-point, these highly effective workouts only took about 20 to 30 minutes.

Workout Details

At its core, the 10-20-30 program is modeled after the Fartlek approach by involving short bursts of running with the speed adjusted by how you’re feeling.

A typical workout following this new protocol would look like this:

  1. A 10-minute warmup. The runners in the original study ran just 3/4 of a mile for their warmup, with no regard to time.
  2. Jog for 30 seconds, run for 20 and then sprint for 10. Repeat this same pattern four more times, follow this routine for five straight minutes.
  3. Walk or jog for 2 minutes as an active rest.
  4. Repeat steps 2 and 3. Cycle through these intervals two or three times. Runners in the study eventually worked their way up to four of these sets.

The original study didn’t list any sort of cool-down but a 10-minute walk is generally recommended to wrap-up your workout.

Because this approach allows you to adjust the speed of each interval, whether it be jogging, running or sprinting, and the number of times you repeat the pattern, it’s easily adapted to your fitness level.

Expert Reception

In general, most experts who reviewed the research found no problems with the study methodology or the program that the study produced. A few authorities have questioned the effectiveness of this type of workout for elite-level athletes.

Others have expressed doubts regarding the trustworthiness of the touted benefits since the subjects used were all experienced runners. These detractors feel that those benefits are to be expected by runners who suddenly shift to an easier training method.

Overall, however, both anecdotal and expert reports have supported the use of 10-20-30 intervals.

Have you been able to incorporate 10-20-30 into your workouts? Please share your experience in the comments.




Rest Periods – A Vital Part of any Fitness Routine

When designing their fitness routine — or even just talking about it — most people will discuss their strength training, cardio training, flexibility and diet. Few, however, will even mention their rest periods.

Most exercisers figure that if some exercise is good for you, then more is even better, but this practice can be counterproductive and even cause injury. Understanding what rest does for you body will help you appreciate the importance of rest days in your schedule.

What Happens During Rest?

Put simply, your muscles grow during rest, not exercise. During exercise the muscle fibers break down and your stores of glycogen, your body’s main fuel source, are depleted. This is true for both cardiovascular exercise and strength training. When you allow yourself periods of rest, however, the muscles adapt to the challenge by rebuilding and increasing in strength. Without sufficient rest, your muscles will continue to break down, leading to overtraining injuries.

The psychological effects of taking time to recover shouldn’t be overlooked either. Rest will give you something to look forward to during particularly difficult workouts, and leave you feeling refreshed and ready.

Symptoms of Overtraining

Overtraining can manifest itself in a variety of ways. When a particular set of muscles are not given time to recover and refuel, pain and any number of injuries can result. On a broader scope, overtraining can adversely affect your entire body — both physically and psychologically — by upsetting the delicate balance of the hormones DHEA and cortisol.

These two hormones have contradicting effects: DHEA builds muscle while cortisol tears it down. In a healthy, well-rested body they are used to guide muscle growth in response to the stresses of the environment. However, in an overtrained body, DHEA production is reduced and cortisol greatly increases. This is probably because cortisol, which is sometimes called the “stress hormone,” is released in response to periods of perceived starvation or danger, causing the body to cut back on expensive metabolic actions and horde fuel in the form of fat. This hormone imbalance can lead to exhaustion, mental confusion, moodiness, nutrient deficiencies, and increased blood pressure and cholesterol.

How Much Rest Do You Need?

Exactly how much rest you need in between exercise sessions depends on many factors, including your genetics, fitness level and overall lifestyle. At the very least, one day a week should be scheduled as a rest day.

A good way to decide how much rest you need, and when to schedule in your rest days, is by keeping a training log and paying attention to how you feel. A detailed log will allow you to see how your body responds to certain stresses and redesign your program accordingly. If, for example, you notice that your time for a distance you routinely run has increased, it’s likely because you were not properly rested, and you can adjust for future runs accordingly.

Active Rest

Rest and recovery doesn’t have to mean complete inactivity. Depending on your fitness goals, you may benefit more from “active rest” than from simply taking a day off. Active rest can generally take two forms: cross-training or a light workout.

Cross-training allows you to work in an activity that isn’t usually your main focus. For example, if your main sport is running, you may chose to strength train as a form of active recovery. If you usually ride a bike, go swimming instead. If you do try cross-training, though, it’s important not to overwork any muscles that are already sore from your normal workout.

Light workouts keep you involved in your sport, but at a reduced intensity. Although your total distance may remain the same as during a more difficult day, your heart rate should only be at about 70 to 75 percent of your maximum. As a general rule, on these “easy” days you should exercise at a pace that allows you to comfortably carry on a conversation. Runners World Magazine suggests that these light workouts should account for 80 to 85 percent of your total weekly mileage.

Although it can be difficult to take a day off or even take it easy on yourself, proper rest and recovery is a vitally important step towards reaching your fitness goals.

Have any tips for incorporating rest into your schedule? Please share them in the comments!