Chapter 25:
Interval training guidelines
Interval training is an advanced technique that can be used to improve fitness level and
increase fat loss. Generally defined, interval training is any activity which alternates periods of
high intensity activity (i.e. sprinting) with periods of lower intensity (i.e. walking or slow jogging).
Weight training can be considered a special case of interval training but is discussed separately.
As with aerobic exercise, interval training is discussed relative to the FITT equation.
Recall that interval training is limited without dietary carbohydrates and is not an appropriate
form of exercise for individuals consuming zero carbohydrates on the SKD. Individuals on a CKD
or TKD may use interval training.
Interval training requires a few special considerations. First and foremost, the risk of
injury with interval training is higher than with aerobic exercise due to the increased intensity.
Individuals beginning an exercise program are encouraged to develop a basic level of aerobic
fitness (a minimum of four weeks, three times per week, 30 minutes per session at 60-65% of
maximum heart rate) before incorporating higher intensity interval training.
Second, interval training should be gradually incorporated into training and the number
and length of the intervals should be progressively increased as fitness level improves. Third,
interval training may or may not be appropriate for bodybuilders. Done in excess, it may cause a
loss of muscle size and strength by making Type II muscle fibers more Type I in nature.
However, some individuals have found that interval training, performed judiciously, improves fat
loss with no loss in muscle mass or strength. Finally, endurance athletes looking to maximize
performance will need to perform interval training during specific periods of their training.
Frequency
As a very high intensity activity, interval training should be performed a maximum of
three times per week and many individuals find that one or two interval sessions are plenty.
During periods where interval training is incorporated, other forms of high intensity training may
need to be reduced to maintenance levels (i.e. weight training for the legs may be reduced to once
per week if intervals are being performed). Additionally, intervals should take the place of a
normal aerobic training session. An individual performing 4 aerobic training sessions who wished
to incorporate intervals once per week should reduce aerobic training frequency to 3 times
weekly.
Intensity
Intensity of interval training may be anywhere from lactate threshold to maximum. To
begin interval training, individuals should use intensities just above lactate threshold (generally
around 75-85% of maximum heart rate). As fitness improves, higher intensities (up to 95% of