Interval Training – Sat 5.27.17
We’ve been using CrossFit’s first article, What is Fitness? to discuss their definition of fitness. This is CrossFit’s view of interval training:
Skill: movement review and warm up
Conditioning: Come in and find out! Bring a Friend!
The key to developing the cardiovascular system without an unacceptable loss of strength, speed, and power is interval training. Interval training mixes bouts of work and rest in timed intervals. Figure 3 (above) gives guidelines for interval training. We can control the dominant metabolic pathway conditioned by varying the duration of the work and rest interval and number of repetitions. Note that the phosphagen pathway is the dominant pathway in intervals of 10-30 seconds of work followed by rest of 30-90 seconds (load:recovery 1:3) repeated 25-30 times. The glycolytic pathway is the dominant pathway in intervals of 30-120 seconds work followed by rest of 60-240 seconds (load: recovery 1:2) repeated 10-20 times. And finally, the oxidative pathway is the dominant pathway in intervals of 120-300 seconds work followed by rest of 120-300 seconds (load:recovery 1:1). The bulk of metabolic training should be interval work.
Interval work need not be so structured or formal. One example would be to sprint between one set of telephone poles and jog between the next set alternating in this manner for the duration of a run.
One example of an interval that CrossFit makes regular use of is the Tabata Interval, which is 20 seconds of work followed by 10 seconds of rest repeated six to eight times (www.cbass.com/INTERVAL.HTM). Dr. Izumi Tabata published research that demonstrated that this interval protocol produced remarkable increases in both anaerobic and aerobic capacity.
It is highly desirable to regularly experiment with interval patterns of varying combinations of rest, work, and repetitions.
One of the best Internet resources on interval training comes from Dr. Stephen Seiler. His article on interval training and another on the time course of training adaptations contain the seeds of CrossFit’s heavy reliance on interval training. The article on the time course of training adaptations explains that there are three waves of adaptation to endurance training. The first wave is increased maximal oxygen consumption. The second is increased lactate threshold. The third is increased efficiency. In the CrossFit concept we are interested in maximizing first wave adaptations and procuring the second systemically through multiple modalities, including weight training, and avoiding completely third wave adaptations. Second and third wave adaptations are highly specific to the activity in which they are developed and are detrimental to the broad fitness that we advocate and develop. A clear understanding of this material has prompted us to advocate regular high intensity training in as many training modalities as possible through largely anaerobic efforts and intervals while deliberately and specifically avoiding the efficiency that accompanies mastery of a single modality. It is at first ironic that this is our interpretation of Dr. Seiler’s work for it was not his intention, but when our quest of optimal physical competence is viewed in light of Dr. Seiler’s more specific aim of maximizing endurance performance our interpretation is powerful.
Dr. Seiler’s work, incidentally, makes clear the fallacy of assuming that endurance work is of greater benefit to the cardiovascular system than higher intensity interval work. This is very important: with interval work we get all of the cardiovascular benefit of endurance work without the attendant loss of strength, speed, and power.