AUGUST 2007 - Pg 26

FAST LANE - WARMUPS - BY ED EYESTONE

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POWER ON “Fast-twitch” muscles to maximise your potential.

TRAIN YOURSELF TO RUN WITH MORE MUSCLE

Runners usually talk about muscles in terms of quads, glutes and hamstrings. Exercise physiologists, on the other hand, talk about muscles in terms of fast-twitch and slow-twitch – which is one reason why physiologists aren’t invited to many parties. Most of our 600 skeletal muscles are composed of a mixed ratio of three different muscle-fibre types that vary in their abilities to produce force and energy. Slow-twitch muscle fibres, also known as type I, have low power but high endurance capabilities.

Fast-twitch muscle fibres, which come in two varieties (type IIa and type IIb), have low endurance but exert more force than slow-twitch fibres. All of these muscle fibres come along for the ride when you run, but some get a better workout than others, depending on your pace. All easy running is handled by slow-twitch muscle fibres – no surprise there.

As running intensity increases, more slow-twitch fibres are recruited. Once you’re running at moderate intensity, fast-twitch type IIa fibres join their slow brothers in action. And as you progress from moderate to maximum muscle force (think sprinting), fast-twitch type IIb fibres are called upon.

As a distance runner, you may think you only need to train those slow enduranceoriented fibres. But even marathoners need to develop their fast-twitch fibres for peak performance. Early on in a marathon, runners use mainly slow-twitch and a few fast-twitch IIa fibres. As the race goes on and muscle glycogen is depleted, however, more fasttwitch IIa fibres are needed to maintain muscle force. And as the slow- and fasttwitch IIa fibres become depleted late in the race, the IIb fibres need to pitch in. So if you fail to train your fast-twitch buddies, they won’t be able to come to the rescue late in a long run.

To make sure your fast-twitch fibres are there for you, whether you’re pushing the pace in a 5-K or gutting out the last few kays of a marathon, you need to include a mix of faster workouts in your training every week.

The workouts below, numbered from one to six, represent a continuum that progresses from moderate to maximum intensity. As you move from tempo runs to long intervals to repetitions to sprints, you increase the percentage of fast-twitch fibres used: You recruit more fast-twitch IIa fibres during the tempo runs and intervals, and press the fasttwitch IIb fibres into action during the shorter, faster repeats.

Pick any two workouts each week, and do them all at least once a month. But don’t let more than two weeks pass without doing at least one of the last four workouts (the highest intensity) to maximise your fast-twitch potential.

THE WORKOUTS

Build both types of fast-twitch muscle fibres by running two of these workouts per week. Be sure to include at least one of the last four workouts every two weeks. Run one or two easy kays before and after each workout to warm up and cool down.

1 STANDARD TEMPO RUN:
25 to 30 minutes at 15 seconds slower
than 10-K pace

2 LONG INTERVALS:
4 x 1-K at 5-K race pace with 3 to 4
minutes jog recovery

3 HILL REPEATS:
2 sets of 6 to 8 x 150-metre hill repeats.
Sprint up, walk down.

4 SPEED REPETITIONS:
8 x 400 metres at kilometre race pace
with 2 minutes jog recovery

5 SPRINTS:
8 x 200 metres at 800-metre race pace
with 200-metre slow jog recovery

6 STRIDES:
10 to 12 x 100-metre strides.
Stride the straightaway, jog the turn.

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