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How to Design Interval Training Workout Routines

Learn how to design a safe and effective interval training workout routine

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Updated May 19, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

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What Is Interval Training?

Interval training is a method of fitness training that combines short, high intensity bursts of speed with short recovery phases that are repeated throughout a single workout. Interval workouts can be sophisticated and structured specifically for an athlete based upon anaerobic threshold testing (AT) or they can be casual, unstructured bursts of speed added to any workout as the athlete desires.

Interval training has been shown to improve exercise efficiency and allow an athlete to exercise at a higher intensity for a longer period of time before muscle fatigue and pain slows them down. In addition to improving athletic speed and endurance, high intensity intervals help burn more calories, and may lead to faster weight loss.

Interval Training Safety

Before you begin an interval training workout, it's important to have an OK from your physician. High intensity intervals are extremely demanding, and for those with underlying heart disease, high intensity training may even be deadly. Before adding any high intensity training to your exercise routine, you should have a solid base of overall fitness. Beginners need to start very slowly, performing less intense, short intervals (less than 30 seconds), with fewer repeats and more rest between workouts. Elite athletes can increase the intensity, time and frequency of training.

Interval Training Tips for Beginners

If you are new to interval training, follow these guidelines before progressing to high intensity training workouts.
  • Get your physician's clearance and know your limits.
  • Always warm up well before performing intervals.
  • Start slowly with simple walk / jog intervals.
  • Bring your heart rate below 100 to 110 bpm during the rest interval.
  • Increase either interval intensity or duration, but not both in one workout.
  • Train on a smooth, flat surface to ensure even effort.
  • Stop at the first sign of pain.

Basic Interval Training Workout Design

The basic variables manipulated when designing an interval training program include:
  1. Duration (time / distance) of intervals
  2. Duration of rest / recovery phase
  3. Number of repetitions of intervals
  4. Intensity (speed) of intervals
  5. Frequency of interval workout sessions

Duration of the Intervals

Intervals can be short or long, and most endurance athletes will use a combination of the two during training.
  • Short Intervals (6-30 Seconds)
    Short intervals generally last from six to 30 seconds and produce a moderate amount of lactic acid, so they are a good way for beginners to get started in interval training. Intervals as short as six seconds have been shown to improve both speed and endurance in recreational exercisers. Thirty-second intervals seem to produce better outcomes for competitive athletes, but because six-second intervals result in less muscle damage and faster recovery, they are a recommended starting place for novice athletes.
  • Long Intervals (2-3 Minutes)
    Long intervals generally last from two to three minutes and are very demanding, and damaging to muscle tissue. Performed all-out, long intervals result in greater muscle damage, a greater need for oxygen, and faster depletion of muscle glycogen. Longer intervals also require a longer rest phase. Intervals lasting longer than three minutes are less common and should not be done more than every few weeks.

Duration of the Rest / Recovery Phase

The shorter the interval phase, the faster the recovery for the next interval. If you are doing 10-second intervals, you may recover within 60 seconds. Trained athletes performing long, three-minute intervals may be ready for their next interval after two minutes of rest. In general you want to rest long enough to slow down your breathing rate and relieve any muscle burning or fatigue. Never start an interval if muscle burning or pain still exists. If muscle burning or pain persists despite rest, it's time to end the workout.

The recovery phase is unique to each athlete and you will have to find what works best for you through trial and error. Some athletes monitor heart rate and wait until they return to 50 or 60 percent of max heart rate before beginning another interval. Others simple wait until they "feel" recovered. Over time you will find out what works best for you.

Number of Repetitions of Intervals

How many intervals you perform in one workout depends on your fitness level. You may go for a specific number of reps, but if your muscles ache, become stiff or muscle burning persists despite rest, it's time to end the workout. If you push through these symptoms, you are risking injury, muscle damage and a longer recovery phase. Additionally, continuing intervals with fatigue reduces the effectiveness of the workout and reduces, rather than improves, your performance.

Intensity of the Intervals

If you have an exercise test done at a sports performance lab, you will most likely use heart rate or lactate threshold to determine your interval intensity. In general, short intervals are all-out efforts pushing upwards of 90 percent of VO2 Max. Long intervals will be significantly lower in intensity in order to maintain a steady effort for the duration of the interval. Beginners should start with lower intensity efforts to avoid injury and overtraining.

Frequency of Interval Workouts

Interval training is demanding. When you exercise at a high intensity, muscle fibers are damaged, so it's essential to allow time for recovery before you train hard again. Few athletes will benefit from performing interval workouts more than twice per week. And at least 48 hours of recovery should be allowed before considering another high intensity training workout. The day after an interval training workout, it's helpful to perform a low volume, slow recovery workout. Watch for signs of overtraining, such as higher than normal resting heart rate the day after a workout, mild leg soreness, general aches and pains, or a washed-out tired feeling that doesn't go away.

Sample Short Interval Training Workout

A sample short interval training session may look like this. After a thorough warm up of 5-10 minutes of easy exercise, perform one short, half-speed, 10-second interval. This interval is used to increase range of motion and blood flow to the muscles needed to perform the all-out effort. When you feel warm and ready, begin your first interval.

Complete a six-second intense intervals and rest until your breathing slows and any muscle burning disappear. As soon as you feel recovered, repeat the next six-second interval. You can repeat 10 to 20 such intervals, but stop as soon as your muscles feel stiff or any muscle burning persists. Finish your workout with 10 minutes of easy exercise, such as spinning on a bike or walking.

Sample Long Interval Training Workout

A long interval training workout will evolve over time as you move from short intervals to long intervals. Over several weeks, you will extend your intervals from 10 seconds to 30 seconds to two minutes. As you increase your interval duration, decrease the exercise intensity interval repetitions until you can maintain a steady pace throughout repeated intervals. Just as in the short intervals, rest until your breathing slows and any muscle burning disappears, before you start another interval. As you begin performing long intervals, you will reduce the number of intervals performed during a workout (two to six) and you will reduce your intensity (speed) relative to the short intervals.

Common Forms of Interval Training

It is recommended that you consult an athletic trainer, coach or personal trainer prior to designing an interval training program.

Sources

ACSM Fit Society Page. American College of Sports Medicine [www.acsm.org] Winter 2009-2010.

Burgomaster KA, et al. Effect of Short-Term Sprint Interval Training on Human Skeletal Muscle Carbohydrate Metabolism During Exercise and Time Trial Performance. Journal of Applied Physiology, February 2006.

Burgomaster KA, et al. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology, February 10, 2005;

Hazell TJ, et al. 10 or 30-s sprint interval training bouts enhance both aerobic and anaerobic performance. European Journal of Applied Physiology, September 2010

Hoyt, Trey. Skeletal muscle benefits of endurance training: mitochondrial adaptations. American Medical Athletic Association Journal, Fall 2009.

Roels, et al. Effects of Hypoxic Interval Training on Cycling Performance. Medicine & Science in Sports & Exercise. January 2005.

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