The Magic Kay

How to adapt this time-tested workout to boost your fitness or set a PB.
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When it comes to effective workouts, intervals (or kilometre repeats) are a classic and versatile training tool. The kilometre, after all, lies at the very heart of the sport, as the unit from which all things running are measured – speed, daily distance, races, even lifetime achievement. Plus, by tweaking the pace, the number of intervals, and the duration of the recovery between efforts, runners can adapt the intervals to any goal – whether it’s improving fitness or setting a marathon PB. “You can do kilometre intervals on the road or a track, and they can be done in a number of ways to accomplish different training goals,” says racing coach Tony Coffey.

The kilometre is a “middle distance.” It’s short enough to be run fast (by experienced runners) to build speed. But it’s also long enough to build stamina, when performed at tempo pace. “Intervals provide excellent allaround conditioning for runners competing in most any distance,” says running coach John Kellogg, who has worked with professional and varsity athletes for 29 years. Here’s how – and when – to use kilometre intervals to boost endurance, get faster and practise pacing.

BUILD STAMINA
Runners often develop stamina with tempo, or lactate-threshold runs (typically 20 to 40 minutes at a “comfortably hard” pace). However, you can break a
planned tempo run into kilometre intervals, with quick recovery, to get the same benefits with less fatigue, a particularly useful strategy for novice racers. More
seasoned runners may find they can add volume – that is, turning a planned 5km tempo run into three or four 1.5km intervals.

Make it harder: Do intervals on a slight grade. The uphill interval develops leg strength, the downhill improves leg turnover. Both help you run faster.

THE WORKOUT
Three to 10 1-K repeats at tempo pace (about half-marathon pace, or 5-K pace plus 20 to 30 seconds) with a 60-second rest between intervals. “The short rest keeps your heart rate up, but you still get the physical and mental break of the rest period,” says Coffey. Newer runners may take a two- to three-minute walk break; the goal is to run each kay at close to the same pace.

INCREASE SPEED
To get faster, you have to increase your VO2 max, or the amount of oxygen your body uses to produce energy, which means running short intervals at a speed faster than 5-K race pace. But for beginners or those new to speedwork, that pace can be impractical. Enter the kilometre. “You can run kilometre intervals at 5-K or even 10-K pace and still sufficiently target VO2 max,” says professional team coach Andrew Kastor. “Those speeds are more manageable.”

THE WORKOUT
Three to five kilometre repeats at 5-K to 10-K pace with two to four minutes rest between intervals. If you’re aiming for a 5-K or 10-K, do this workout every second or third speed session. Runners training for a half or full marathon should do this workout once every two weeks. If your 5-K pace is slower than 5min/km, run 800m intervals instead of kilometre repeats to ensure you can maintain the pace and to avoid undue fatigue, says Kastor.

LEARN RACE PACE
“Doing kilometre repeats at race pace is critical for new and experienced racers because they really teach you that specific pace,” says exercise physiologist and running coach, Susan Paul. “It mimics the physical and mental challenges of racing.” Runners targeting 5-K and 10-K races can match the number of intervals to the race distance (four to five intervals for a 5-K, for example) to serve as a dress rehearsal for the actual event.

THE WORKOUT
Three to 12 1-K repeats at goal race pace with a two to five-minute rest in between. “Pay attention to the stride, the arm swing and the breathing rate,” says Paul. “This will help your body ‘memorise’ that speed.” When you first try the goal-pace-kilometre workout, do two to three intervals followed by a three-to five-minute recovery jog. As you get closer to your goal race, add more intervals and decrease the recovery period. To fine-tune your timing, include this workout in the final three weeks.

HOW TO TIME YOUR PERFECT WORKOUT
Kilometre repeats provide benefits during every stage of training.

THE WORKOUT AND WHEN TO RUN IT
3 to 10 x 1km at tempo pace:
Early season, or any time to maintain fitness
3 to 5 x 1km at 5-K pace:
Midway in training; 10 to 14 days before racing
3 to 12 x 1km at goal race pace:
Three to five weeks before goal race