Intermittent Aerobic Training - Part 2 - Tech Brief

American Fitness, May-June, 2002 by Scott Roberts

Part One of Intermittent Aerobic Training (March/April 2002 issue) reviewed the results of recent studies showing that intermittent aerobic exercise training (IT), compared to continuous aerobic exercise training (CT), elicits similar improvements in aerobic capacity, but results in greater reductions of body fat percentage and weight as well as improvement in anaerobic capacity.

Part Two will concentrate on how to exercise using an IT training protocol. In order to benefit from IT training, purchasing a heart rate monitor is recommended. A heart rate monitor makes IT training easier to regulate because it provides an accurate, immediate assessment of your heart rate and exercise intensity.

Overview of Intermittent Training

The basic principle of IT training is the continuous varied intensity throughout an exercise session. Intensity can be varied by speeding up, slowing down, keeping the speed or RPMs the same or changing the resistance. For example, when exercising on a bicycle ergometer, intensity can be varied by pedaling faster, slower or at the same RPM and changing the resistance setting. Many exercise machines now have features that allow you to program intensity intervals. If you are walking outside, some of the easiest ways to vary intensity is to choose a location that has changes in elevation, speed up or slow down your pace.

Changes in intensity are best monitored using a heart rate monitor or RPE scale. With IT training, a set level of work is performed until the client's heart rate reaches 5 bpm above a predetermined training heart rate (THR). At this point, intensity is reduced during the active rest period until the heart rate falls 5 bpm below the client's THR. Active rest is defined as slow, continuous movement (rating of perceived exertion 1 of 10 on the Borg scale) using the same muscle groups involved in the preceding aerobic activity. During IT training, the exercise/rest stages within the 10 bpm range are performed for a period of standard aerobic exercise time (20 to 30 minutes). Research shows each exercise/rest interval generally takes about one minute to complete. As clients improve their fitness levels, exercise/rest intervals are reduced and an increase in intensity is often needed.

IT training takes time to become accustomed to. Trainers may have to spend additional time working with clients until they feel comfortable with the IT protocol. However, most clients will eventually be able to exercise independently.

Establishing Initial Exercise Intensity Levels and Progression

Initial exercise intensity levels for IT training are established by utilizing the same standard criteria used with CT training. Initial exercise intensity levels should be determined following a careful review of a client's health, current fitness level and possibly the results of a standardized exercise test. The American College of Sports Medicine (ACSM) recommends an intensity exercise corresponding between 55/65 percent to 90 percent of maximum heart rate (HRmax) or 40/50 percent to 85 percent heart rate reserve (HRR). Progression to higher training intensities depends on the client's fitness level, goals, age and tolerance to current exercise training, medical and health status. IT training can be incorporated into all fitness industry standards, guidelines and types of aerobic exercise workouts.

Conclusion

Initial reports on low-intensity IT training result in greater improvement of anaerobic capacity and weight loss--similar to improvements in aerobic capacity of traditional continuous training. While the benefits of IT training are not completely understood, IT training allows clients to exercise at an overall higher intensity level for a set period of time. IT training improves anaerobic capacity faster, which results in diminished lactic acid accumulation and enhanced lactic acid buffering--primary benefits of endurance training. In addition, IT training elicits a higher post-exercise metabolism, which enhances overall caloric expenditure. Several studies are being conducted to determine if IT training improves fitness levels faster than CT training and to what extent IT training is more beneficial than CT training.

References

(1.) Billat, V.L., Flechet, B., Petis, B., Muriaux, G. & Koralsztein J. (1999). "Interval training at V[O.sub.2]max: effects on aerobic performance and overtraining markers." Medicine and Science in Sports and Exercise. 31 (1): 156-163.

(2.) Brockman, L., Berg, K., & Latin, R. (1993). "Oxygen uptake during recovery from intense intermittent running and prolonged walking." Journal of Sports Medicine and Physical Fitness, 33 (4), 330-336.

(3.) Mayer, H.C., DeRose, D.J., Charles-Marcel, Z.L., Sergev, O., Roberts, S.O. & Nethery, V.M. (2001). "Aerobic Intermittent Training: Effects on Fitness, Body Composition and the Thyroid." Medicine and Science in Sports Exercise (in review).

(4.) Ohlsen, M. and Roberts, S.O. (2001). "The Effects of Continuous vs. Intermittent Training on Aerobic Capacity, Body Composition and Blood Lactate Response in Sedentary Females" (Master's thesis).