Intervals for Fitness and Fat Loss
(Q & A with Dr. Pat O'Shea)
“Short-term intense interval training is highly effective in altering the ratio of lean body mass to fat without compromising muscle mass.” Pat O'Shea, Ed.D.

For two months now we've been challenging the common belief that low intensity, long duration exercise is best for fitness and fat loss. We've shown that very brief and very hard interval training is amazingly effective in developing both aerobic and anaerobic capacity - and far superior for fat loss. (See articles #10 and 11)

Now, it's time to step back and ask where intense intervals fit in the total spectrum of fitness training. What's best for endurance athletes? Bodybuilders? Older athletes? For total conditioning?

Who better to go to for a broader perspective on interval training than Patrick J. O'Shea, Ed.D, Professor Emeritus of exercise and sports science at Oregon State University? Not only has Pat been a student of sports physiology for four decades, he has excelled as an Olympic and power lifter, a cyclist, a mountain climber, a skier and a coach.

What's he doing now? Pat tells us he plans to compete in cycling and bowling next August at the Nike World Masters Games to be held in Portland, Oregon.

Who better indeed?

(For more information on Dr. O'Shea see “Guru of Quantum Strength,” article #5 on this site).

We prevailed on Dr. O'Shea to review our articles, “Forget the Fat Burn Zone” and “In Search of the Ideal Aerobics Routine.” We then asked him some specific questions designed to focus his vast knowledge and experience on the subjects we've been discussing.

We were very interested in what Pat had to say, and believe readers will be informed as well. Enjoy. (Italicized emphasis in the answers is ours.)



Bass: You've used intervals in your own training and also published research on the subject. Were you surprised that Dr. Tabata's group found that only 6-8 very hard 20 second intervals with 10 second rest periods substantially improved both aerobic and anaerobic capacity?

O'Shea: No, not at all. Dr. Tabata's study is excellent and his findings confirm previous studies that have looked at the effects of intense interval training on aerobic and anaerobic performance. (See O'Shea, John P., Bicycle Interval Training for Cardiovascular Fitness. The Physician & SportsMedicine 10:156-162, October, 1982). Coaches and athletes need to understand however, that short-term intense interval training has very limited application to long-distance events such as marathon running and the Tour de France. Long distance endurance athletes need efficient “fat burning” bodies. Their muscles must be trained to utilize energy from free fatty acid oxidation while conserving the limited stores of glycogen which are necessary for nerve and brain function. (Nerves and the brain derive energy only from glycogen - not fat.)

Long-term aerobic training increases the enzymes associated with fat metabolism and trains the working muscles to utilize oxygen more efficiently. The result is an increase in oxygen uptake capacity of the trained muscles, and not in the untrained. This is important for athletes to know as it involves the principle of specificity. For example, competitive swimmers develop high aerobic capacity specifically for swimming. Out of the water their aerobic conditioning is not transferable to running, because different sets of muscles are involved which are aerobically untrained.

To train, smart athletes need at minimum an elementary understanding of the cardiovascular and circulatory processes leading up to aerobic metabolism within muscle. While the following description is highly simplified, it does provide an overall picture of the steps involved. Initially, it begins with the ability of the lungs to take up and then unload oxygen in the blood; the ability of the red blood cells to pick up the oxygen as it flows through the lungs; the ability of the heart to pump a large volume of blood (stroke volume) to the working muscles; and finally, but most critical, the efficiency of the working muscles to take up oxygen from the blood and use it for oxidative energy production. Physiologically, this whole process is what cardiovascular fitness is all about.

Another important consideration in understanding aerobic and anaerobic metabolism is that muscles differ in their ability to utilize oxygen. Slow twitch muscles are noted for their endurance and have the ability to use large quantities of oxygen required for fat metabolism during aerobic exercise. Fast twitch muscles are the strength and power producing muscles. They are good for explosive bursts of anaerobic energy for sprinting, jumping, lifting and interval work. However, they fatigue fast and are not efficient fat burners. Glycogen is their main source of energy during intense work making them ideal for anaerobic exercise lasting up to three minutes. Exercise lasting longer than three minutes is aerobic.

The bottom line is that short-term intense interval work is not designed to train the body to become an efficient fat burner as is required for long-distance endurance activities. However, for sprint cycling or running (up to 400 meters) intense interval training definitely offers major physical benefits. In the overall scheme of training for athletes participating in stop and go power sports (e.g., football, basketball, ice hockey and gymnastics) short-intense interval work has a major role to play in maximizing performance.

Q. Exercise physiologists have traditionally believed that volume, not intensity, is the key to successful aerobic training. Where do you come down on the volume versus intensity question?

A. My position is that in order to become a successful endurance athlete (cyclists, runner, etc.) one must cross-train. A training program based on volume, such as running a hundred miles a week, will not maximize aerobic capacity or develop a high anaerobic capacity. What is required is a cross-training program encompassing aerobic and anaerobic workouts. The aerobic workout is LSD (long-steady distance) running or cycling at just below the anaerobic threshold (or race pace). During an LSD workout the heart rate is usually 75-85 percent of the age related maximum. (The only time V02max can be utilized to set or measure intensity is in a human performance lab where it can be monitored.) Anaerobic running, on the other hand, consists of interval training at distance ranging from 200m to 800m, and for cycling 800m to 1500m, at a heart rate of 90-95 percent of maximum. Following high intensity interval workouts there needs to be several days of light recovery workouts of low to medium intensity.

Also, both aerobic and anaerobic energy systems can be effectively cross-trained in a single workout session, which should closely duplicate the physiological race demands of volume and intensity. For example, in a 100 mile bike race, which encompasses both high work volume and intensity, it is imperative that the cyclists focus on maximizing aerobic and anaerobic conditioning. Typically, in such a race the cyclist encounters varying terrain from flats to rolling hills and breakaways and attacks by other riders. Aerobic power is essential for sustaining a hard fast pace on the flats, while anaerobic power plays key roles in initiating a breakaway or not getting dropped when one occurs; chasing down a break or lead group; attacking and accelerating on hills; and sprinting to the finish. Anaerobic power and explosive strength are the two factors which allow the cyclists to control the race. Applying strategy that calls for numerous breaks and attacks on hills, an elite cyclist will wear down weaker riders and psychologically destroy them. It is imperative then that a cyclist's long-range training program include lots of cross-training workouts that call for volume (distance) riding interspersed with speed work and interval hill repeats.

Q. In your book Quantum Strength and Power Training (Gaining The Winning Edge) (1996), you wrote: “Statistically, there is a close relationship between V02max and lean body mass.” Were you surprised when the Tremblay group - challenging the common belief that low intensity, long duration exercise is best for fat loss - found that short intervals (30-90 seconds) produced substantially more fat loss for each calorie burned exercising? Why?

A. No, I was not surprised by Tremblay's findings showing that low intensity, long duration exercise is not as effective as short intense intervals in reducing body fat. It is relatively easy to explain why this is so.

During strenuous exercise, the rate of metabolism rises, going to about 15 times the basal metabolic rate (BMR) and even higher during intense interval work. For example, running 5 mi/hr the oxygen uptake required is 28 ml 02/min/kg of body weight with 3.7 cal/hr./lb burned, while a short burst of intense interval work may require 100 ml 02/min/kg with 13.8 cal/hr/lb burned. By maintaining the high level of training over a 5 or 6 week period one would expect a significant increase in the ratio of lean body mass to fat. Over a three month period you would be RIPPED like never before.

Intense interval work utilizes a greater percent of the body's muscles, both slow and fast twitch. Also, performing high intensity work places added energy demands on the respiratory system, cardiovascular system and nervous system. Thus more fat and glycogen are burned to support the expanding energy demands of the body during - and after - intense exercise. In other words, the cost of short intense interval exercise is very high in terms of energy demands in comparison to low intensity aerobic exercise. What's more, while at rest trained active muscles burn more fat night and day, contributing to further fat loss.

Q. I'm preparing for the treadmill test at the Cooper Clinic. (They increase the grade one percent every minute up to 25%, and then the speed, to exhaustion.) In the past, I've lasted between 28 and 29 minutes. Would Tabata's 20 second intervals on the Air-Dyne, rower and treadmill be a good way to prepare? Should I add some training that more closely parallels the test protocol?

A. The key in preparing for a treadmill test is concentrating on improving anaerobic power - i.e. pushing back the anaerobic threshold which is the point at which lactic acid begins to accumulate at a high rate in the blood. This is an indication that oxygen uptake at the muscle cell level can not keep up with the work demands. Once this threshold has been exceeded your V02max is calculated.

Training with an Air-Dyne or rower to raise your anaerobic threshold for the treadmill test is going to produce very limited results. It is not specific enough to the test. Hard interval repeats of 2-3 minutes duration on a treadmill, stairmaster, hill, or stadium steps will provide the best results. These training activities not only develop anaerobic power, but also strong quadriceps that are required to run on a grade.

Q. Is there a lesson here for athletes preparing for specific events?

A. Yes, there is a very important lesson to be learned and understood. While the specificity principle is the cornerstone of athletic training, variety or diversity in training is required to achieve the highest level of total conditioning. Training variability encompasses the concept of cross-training. It allows for the simultaneous training of multiple physiological variables (e.g., aerobic and anaerobic, power, strength, speed, and power) that contribute to peak athletic performance in all sports.

Q. As I point out in Ripped 3, bodybuilders have a problem using aerobics for fat loss, because endurance exercise can work against gains in muscle size. Would the Tabata protocol of high-intensity intervals be good for bodybuilders who want to preserve muscle mass while losing fat?

A. The answer is definitely a big yes. As discussed in question 3, short-term intense interval training is highly effective in altering the ratio of lean body mass to fat without compromising muscle size. Intense interval work is an excellent way of losing weight while simultaneously getting ripped for peak contest shape.

Competitive bodybuilders will find another highly productive method of interval training outlined in my book Quantum Strength & Power Training, Chapter 10, “Interval Weight Training (1WT)”. It is one of the most challenging, intensive methods of cross-training yet devised for muscular endurance and anaerobic power. IWT is heavy-duty quantum training - physically tough and mentally demanding. If you are a serious bodybuilder and like a new challenge try it for several weeks. The results will amaze you.

Q. What about healthy older people who want to be lean and fit? Would it be advisable for them to do short, hard intervals?

A. The answer is yes and no. First, it is not advisable for anyone to attempt interval training without first getting medical clearance preferable from a sports medicine physician who has a clear understanding as to the physical demands to be encountered. For any person having coronary heart disease the answer must be a big no. For a healthy person having a reasonably good level of aerobic fitness - (i.e., a minimum V02max of 50ml/kg/min) there should be no problem. However, as an added safety measure, it would be a good idea to take a treadmill stress test to be sure that there are no cardiac abnormalities.

For best results and safety, the intensity of the interval workouts should be set using a percent of one's age-related maximum heart rate. An easy method of determining maximum exercise heart rate for interval work is to subtract your age from 220 and then use 90-95 percent of that figure. For a 40 year old individual the interval exercise target heart rate would be 171 (220 - 40 = 180 x .95 = 171). Remember too, interval training is very stressful on the body and joints and should not be done more than two times a week. Yes, young athletes are more resilient than master age-group athletes. They recover quicker and more fully between workouts which allows them to do interval training with greater frequency.