Purists may tell you that combining cardio and strength training just won’t work, or creating interval training from ordinary workouts is a waste of time. But athletes who prepare for actual sports – not aesthetic Speedo comparisons up on a stage – know that this is one of the most effective ways not only to gain size, but to gain strength, agility, balance, and performance.

Interval training is a way to work both the aerobic and the anaerobic systems within the body at the same time. It’s an obvious time-saving tool, but also a valuable training tool that nets more calories burned and provides more intensity than most know how to inject into workouts.

For example, during a high intensity effort, or sprint, the anaerobic system uses the energy stored in the muscles (glycogen) for short bursts of activity. Since anaerobic metabolism works without oxygen, the by-product of that kind of workout is lactic acid. (That’s the burn you feel when you’re tired from lifting).

Also during high intensity intervals, when lactic acid builds, an athlete enters oxygen debt. During a recovery phase, heart and lungs work in tandem to recover this oxygen debt and breaks down lactic acid built up through the sprint activity. It is in this phase that the aerobic system is in control, because it uses oxygen to convert stored carbohydrates into energy.

Alternating between these forms takes care of the lactic acid from both phases and allows you to continue to build up endurance and strength, based on the activity and recovery cycles of each, opposing one another.

This repetitive form of training leads to the adaptation response. The body begins to build new capillaries, and is better able to take in and deliver oxygen to the working muscles. Muscles develop a higher tolerance to the build-up of lactic acid, and the heart muscle is strengthened. These changes result in improved performance particularly within the cardiovascular system, but it also benefits the musculoskeletal system in terms of overall density and size.

Interval training also helps prevent the injuries often associated with any form of repetitive endurance exercise, and allows you to increase training intensity without overtraining. This is a neat trick for any bodybuilder and the most logical choice. But it is difficult, so many bodybuilders don’t consider doing it because they are lazy. Adding intervals to a workout routine is a good way to shake things up, it’s a way to make going back to plain heavy cycle workouts, much easier and bearable.

According to the American College of Sports Medicine, you burn far more calories during shorter duration, higher intensity activities and exercise. This can be an advantage to bodybuilders – actually burning fat and maintaining strength during dieting phases. This is the best use for interval training, but it should be endeavored in the off season when calories are not sparse.

You don’t have to be an elite pro athlete or a world class bodybuilder to benefit from interval training that combines cardio and strength training for better cardiovascular health and performance and greater muscular gains and definition than you could imagine in your old routines. But pay close attention to how you feel and set your intensity and duration accordingly.

Safety Tips for Interval Training

• Warm up prior to beginning interval sessions
• Assess current conditioning and set training goals that are within your ability
• Start slowly. (for example: walk 2 minutes/ run 2 minutes) In general, longer intervals provide better results
• Keep a steady, but challenging pace throughout the interval
• Build the number of repetitions over time
• Bring your heart rate down to 100-110 bpm during the rest interval
• To improve, increase intensity or duration, but not both at the same time
• Make any changes slowly over a period of time
• Train on a smooth, flat surface to ensure even effort
• You can also use circuit training as a form of interval training

Advanced Interval Training

You can take a more scientific approach to interval training by varying your work and recovery intervals based on your pre-determined goals. Here are the four variables you can manipulate when designing your interval training program:
• Intensity (speed) of work interval
• Duration (distance or time) of work interval
• Duration of rest or recovery interval
• Number of repetitions of each interval

Not Just for Cardio – Strength Training Benefits

Interval training examples so far have been only cardio to cardio type applications. 2 minutes of running –> 2 mintues of walking

But interval training can also include repetitions and sets performed rapidly and
with varying rest times. Some will do a high intensity, heavy set of leg extensions
or leg press , and then combine it with an immediate pliometric jump set following
that is more endurance based. One is quick burst and the other is endurance
based.

You can do the following:

1 set of squats at 80% of max weight followed immediately by:

1 set of 25 light leg extensions

OR

Up and down a set of stairs 5 times

REST

When preparing for a competition, try using cardio intervals 1 to 2 times per week
for a greater calorie burning session. But throughout the year, try doing interval
training during cardio workouts and strength workouts. Combining the two will give
you your best results (use the example given last with squats + stairs).

Do a year of this kind of training, on a relatively regular basis – cycle it like anything
else you may cycle – and your body will be completely different within a year’s
period of time. I guarantee it!