people exercising using weights

Interval Training: Making Cardio Count


By:  Dr. Mark Force, DC

Most of the cardiovascular training/exercise that most people do most of the time is mostly wasted time and doesn’t get efficient results. That doesn’t mean getting up off the couch isn’t a good thing. Taking a walk, playing some tennis, getting out for a hike, going to a spin or dance class, or doing some yoga; these things are all good.

Regular aerobic exercise done at a steady pace is ineffective at increasing VO2 max, anaerobic threshold, heart rate recovery times, improving function of your autonomic nervous system, or even increasing metabolic rate. Yet overwhelming research shows that exercising regularly and effectively is the single best way to improve your health and age well.

Aerobic training in this way gives you the same cardiovascular endurance as exercising for long distances or periods while at the same time decreasing the wear and tear caused by frequent training of more than half an hour at a time.

You do want to take advantage of what cardiovascular training can really do for you. Vitamin Ex is probably the single most important supplement you can take to make your life better, healthier, longer, stronger, vital, richer, and more fun. Many sleep disorders in my clinical experience are an exercise (vitamin Ex) deficiency and exercise can be key component to get people to heal from chronic illness.

You have to know how to get the most out of it and make getting the exercise into your routine. We all have busy lives and we have to make our exercise time efficient.

Interval Training

What does work is interval training – working out very hard for short intervals, resting, and then exercising again.

Interval training is proven in research to significantly improve VO2 max, anaerobic threshold, heart rate recovery times, heart rate variability (measures the efficiency of your autonomic nervous system), and metabolic rate (as much as 10 times more effective for fat loss than regular aerobic exercise).

The best equipment for doing this is the simplest – calisthenics, wind sprints, jump rope, or rapid, high rep free weight training (barbells, dumbbells, kettlebells, sandbags).

How Long To Train

A good standard for the length of an interval training workout is 12 minutes. When starting out you can train for less duration and increase the number of intervals and time of your workout as you become better conditioned.

If you are very well conditioned, you can do interval training for 20 minute sessions and, if you’re wanting to have elite levels of conditioning, you can do interval training for up to 40 minutes. Doing interval training for longer than this diminishes the training effect because it requires less intensity of effort.

You will experience a sense of energy, well-being, and calm, if you are doing the interval training for the right amount of time. This is from the tonic effect of the exercise improving function of your nervous system and it can be seen through improved heart rate variability, a measure of the function of your autonomic nervous system.

If you go for too long a time, you will feel weak, fatigued, and stressed. For people who have very weakened systems, their exercise tolerance is very low and they may be able to exercise for only 4-6 minutes at a time. Even in this group having low exercise tolerance, the interval exercise is very important for their health and well-being and the interval exercise can be a critical catalyst for their systems to heal.

Low exercise tolerance individuals should still exercise regularly and with intensity, but moderate the length of time working out. Exercise tolerance will improve along with greater robustness to the nervous system.

How To Structure Your Intervals

Begin with 30/30 intervals. This means you will be doing exercise intervals of 30 seconds and rest intervals of 30 seconds. Take a test run for 10-12 minutes using running/sprinting, biking, rowing, calisthenics, jump rope, weight lifting (dumbbell, barbell, kettlebell, or sandbag.

Pick a basic movement that puts demand on the whole body. If you’re out of shape, consider something like jumping jacks, doing partial squats from a chair, or running in place. If you’re in good shape, you can use full squats, squat presses, kettlebell swings, kettlebell snatches, cleans, squat presses, and burpees.1 If you’re in great shape, you’ll already know what movements to try.

You can use shorter rest intervals as your conditioning improves. A standard interval format I use for greater intensity than the 30/30 intervals, is a 20/10 interval format with 20 seconds of exercise with 10 seconds of rest.

You can use a watch or clock to monitor your intervals, but I prefer an interval timer. These electronic timers can be programmed for interval format and time of workout/ number of intervals. For instance, I can program the timer for 30 second work intervals, 30 second rest intervals, and for 12 cycles. The timer will beep and/or vibrate at the beginning of each interval. This will be a 12 minute workout.

My favorite interval timer is the Gym Boss, available on the internet for ~$20 ( It is a worthwhile investment to make the interval training easier and more effective.

Adjusting Training Frequency

A generally effective format for introducing interval training is to train three times a week for a week or two if you don’t regularly work out and then advance to six times a week after two weeks. You can advance once you feel fully recovered before your next session. In other words, once you feel fully recovered before your next training session when training every other day, you are ready to train daily.

If you want to recover from illness or chronic stress or are trying to optimize fitness, exercise twice a day after an initial daily training period of a week or two. This is the format used by elite athletes and military to optimize physical and neurological fitness who may train up to eight times a day for specific periods.

When using this high frequency format keep your training sessions short (~10-12 minutes). High frequency training can be useful for up to one month at a time, at which point training frequency should be cycled down for a recovery period of one month or more.

High frequency training is in great part done for the benefits to the nervous system, rather than the cardiovascular system. It is an excellent way to improve neurological adaptation to stress and increase adaptation reserve, or the total load of stress to which the nervous system can adapt.

Monitoring Heart Rate

When starting out interval training, you have to get your bearings as to how hard, or intense, your work intervals should be and first you have to figure out your Maximum Heart Rate. The classic way to do this is to calculate your maximum heart rate by subtracting your age from 220 (i.e., if you’re 50 years old, your maximum heart rate would be 170 (220-50 = 170)).

If you’re a beginner, stay in the lower range during work intervals (60-70%). Once you’re feeling more fit and recovering from your exercise more quickly (see the Heart Rate Recovery section below), you can train in the higher range (80-90%) for short periods.

Track your pulse rate periodically while exercising by resting your fingers on your wrist on the same side as your thumb or in the slight depression to each side of the front of your neck. To calculate the beats per minute (bpm), count for fifteen seconds and multiply the count by four.

You may find that using a heart rate monitor is easier for keeping track of your heart rate than using a watch to check your pulse. Some heart rate monitors allow you to program your workouts and keep you at your target heart rate. Alarms remind you when your

heart rate is outside of the target range. Polar and Suunto seem to make the best heart rate monitors. Higher end monitors allow you to analyze your workouts and changes in your fitness.

If you are very fit, you can train at or above you maximum heart rate in short intervals.

If you have major health problems or any reservations about your basic cardiovascular health, see a physician or certified physical trainer or therapist to establish your ability to train and monitor you. The period of interval that you use is variable and can run anywhere from 15 seconds to 5 minutes.

Using Heart Rate Recovery To Know How Hard To Train

Your heart rate recovery is the rate at which your heart rate returns to normal after exercise. Take your heart rate 2 minutes post workout; your heart rate should decrease from your immediately post-workout heart rate by at least 15-25 beats per minute (BPM).

If the decrease in your heart rate is 12BPM or less your workout pace was too great and you have to decrease the percentage of maximum heart rate on your next workout.

Adjust the percentage of maximum heart rate on succeeding workouts until you find the 15-25BPM decrease in your heart rate.

If your heart rate still does not decrease appropriately over the next couple of workouts, consult you primary physician. If your heart rate decreases more than 30BPM post- workout, you can increase the percentage of your maximum heart rate.

Increasing Workload

As you get more fit, you don’t increase the time that you work out, but increase the work done (distance traveled or weight lifted in the same amount of time). When you can do more work in less time, you are fitter.

Vascular Resistance Interval Training and Heart Structure

Aerobic exercise increases the heart size and contractility over time. This results in the increased stroke volume of the heart in trained subjects and their lower heart rate and blood pressure.

Standard aerobic exercise doesn’t increase the heart muscle wall thickness, however, and can result in weakness of the heart muscle wall. By using training that combines cardiovascular (aerobic) training with increased intrathoracic and peripheral vascular pressure through full body high rep resistance training , the heart muscle wall thickness is improved. High rep weight training satisfies this using the full-body, compound movements such as cleans, clean and presses, swings, snatches, and squats. The other exercise that produces this protective effect on the heart is rowing. I highly recommend incorporating high rep weight training and/or rowing into your training regimen.

For more information about Dr. Mark Force, visit his listing at Holistic Healers Directory

Photo By:  Joint Base Elmendorf-Richardson, Flickr Creative Commons

About Dr. Mark Force:

Mark ForceDr. Mark Force is a chiropractic physician and author of Choosing Health

For more information visit

Elements of Health …Natural & Functional Healthcare

8711 E. Pinnacle Peak
Scottsdale, Arizona 85255


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