Did you "Fartlek"?

The term fartlek (Swedish for "speed play") is being replaced now by the general term "interval training" (although true interval training is slightly different).

Whatever term you choose to use (it's fine to call it "interval training") it generally refers to a low to moderate intensity cardio/aerobic exercise session that is interspersed with several brief high intensity ANaerobic periods (intervals) of the same exercise.

Some people simply call this a "go hard-go easy" workout which I guess gets right to the point. Anyway, it might help at this point to again refer to and recall the heart rate training zones so here is that list:

zone 1) warm up/cool down zone 60-70% of MHR
zone 2) basic fitness zone 70-75% of MHR
zone 3) aerobic endurance zone 75-85% of MHR
zone 4) anaerobic lactate AT-LT zone 85-90% of MHR
zone 5) anaerobic speed zone 90+% of MHR

A typical 30 minute "Interval" training session might go something like this:

Warm up and 10-12 minutes at zone 2 pace (basic fitness zone, 70-75% of MHR)

1 minute at zone 4 (ANaerobic lactate zone 85-90% of MHR)

2 minutes at zone 2 pace (basic fitness zone 70-75% of MHR)

1 minute at zone 4 (ANaerobic lactate zone 85-90% of MHR)

2 minutes at zone 2 pace (basic fitness zone 70-75% of MHR)

1 minute at zone 4 (ANaerobic lactate zone 85-90% of MHR)

2 minutes at zone 2 pace (basic fitness zone 70-75% of MHR)

1 minute at zone 4 (ANaerobic lactate zone 85-90% of MHR)

2 minutes at zone 2 pace (basic fitness zone 70-75% of MHR)

1 minute at zone 4 (ANaerobic lactate zone 85-90% of MHR)

3 minutes at zone 2 pace (basic fitness zone 70-75% of MHR)

2 minutes at zone 1 cool down (60% MHR or less)

You get the idea.

Traditional "fartleks" can vary quite a bit more than the sample session above indicates, but the main take away point is that interval training in general involves repeatedly and alternately going from aerobic zone into ANaerobic zone levels of intensity and then back again, all during one continuous session.

There are many (numerous) benefits to interval training but one end result will be that it pushes up your AT (ANaerobic Threshold) and your LT (Lactate Threshold) so that these thresholds are delayed and occur at higher levels of exercise intensity.

This kind of training utilizes and conditions both aerobic and ANaerobic energy systems so that they both become stronger, more efficient and more responsive to demand.

In real life terms, this means that you won't get as out of breath as early, you won't feel that lactate "burn" feeling as early, you won't have to work as hard to go just as fast as usual, and you will burn more calories and fat than you'd do with continuous heart rate training.

Another important benefit of interval training is that it can condition more type 2 (fast twitch) muscle fibers which usually don't get involved as much during low intensity aerobic exercise. Type 2 "Fast twitch" muscle fiber is made for quick and powerful movement but does not have a high aerobic capacity (compared to type 1 slow twitch) unless you train it too.

One recent article I read cited some studies that found interval training to be the "quickest method" to gain cardio/aerobic fitness - better than steady pace (single heart zone) training. Intuitively this makes sense to me as you get your heart rate up quite a bit higher and work the muscles harder with intervals.

A good interval training session for hikers/climbers is to find a short hill nearby and do runs (sprints) up the hill followed by lower paced flat or down hill periods. This can mimic (to some extent) some of the stresses you encounter when hauling heavy packs into thinner air.

Whatever technique you choose just follow the main principles as mentioned above alternating "go hard-go easy". It will get you breathing hard and in training that's a good thing.



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