Winter intervals, set by your race time.

Why intervals belong on the belt in winter

Cold, dark evenings and icy paths make hard outdoor running a gamble. A treadmill takes the gamble out. The belt holds your pace exactly, rests are timed to the second, and the session is the same whether it is minus five or plus ten outside.

The trade-off is boredom and heat, not fitness. Plan the work in short blocks, put a fan in front of you, and keep one outdoor run in the week when the weather allows. The six sessions below cover everything from hill strength to race-pace work, and each one is set from a recent race time so the numbers are yours rather than a guess.

Set your zones from a recent 5K

Find your 5K time in the first column. Every other figure is a pace per kilometre except the last two columns, which are the belt speed in km/h at 1% incline. Use a 10K or half marathon result in the indoor workout builder for the same table at any distance.

Paces come from an equivalent-performance model. Belt speeds are for 1% incline, which matches flat outdoor effort. Easy means that pace or slower.

Six sessions to rotate through the winter

Worked examples below use a 25:00 5K. Swap in your own numbers from the table, or let the builder do it.

1. Incline repeats

6 to 8 × 90 seconds at interval effort on a 5% grade, 90 seconds easy between. Hills build strength and running economy without pounding the legs at full speed, so they suit the base phase. Because a steeper grade costs more oxygen, the belt runs slower than the flat equivalent: for a 25:00 5K, the interval effort of 4:50/km becomes 10.6 km/h at 5%, not 12.4 km/h.

2. Kilometre intervals

4 to 6 × 1000 m at interval pace with 2:30 easy between. This is the classic aerobic-power session. Example: each kilometre in 4:50 at 12.4 km/h. Hold the same speed on rep 6 as on rep 1; if the last one needs a drop, end the set instead.

3. Threshold blocks

3 × 8 minutes at threshold with 2:00 easy jog between. Comfortably hard, short phrases only. Example: 5:16/km at 11.4 km/h. These blocks raise the pace you can hold for 10K and beyond, and they are gentler on the body than faster work.

4. Race-pace repeats

3 to 4 × 1200 m at your 5K goal pace with 2:00 rest. Example: 5:00/km at 12.0 km/h, 6:00 per rep. Use these in the peak phase to make the target speed feel familiar.

5. Sharpener

4 × 400 m at goal pace with 90 seconds rest, in the final week. Short and crisp, it keeps the legs quick without adding fatigue before the race.

6. Steady run

20 to 40 minutes a notch below threshold, after a 10-minute warm-up. Example: 5:41/km at 10.5 km/h. Half marathon plans lean on it most.

Rest, warm-up and belt safety

• Warm up for 10 to 12 minutes at easy pace and 1% incline before any fast rep.
• Rest by slowing the belt to a walk or easy jog. Stepping onto the side rails at speed is how most treadmill falls happen.
• Clip the safety key to your clothing and keep the hand rails clear. Use them for balance when you change speed, not to carry your weight.
• Change the speed early. Press the button two or three seconds before the rep starts so the belt is at pace when the clock begins.
• Cool down for 5 minutes and bring the incline back to 1% before you step off.

Where each session fits in 8 to 12 weeks

• Base: incline repeats, short threshold blocks and easy aerobic running.
• Build: kilometre intervals and longer threshold blocks, with a lighter week every fourth week.
• Peak: race-pace repeats and shorter threshold work.
• Taper: a sharpener, one short threshold run and easy running. The race follows.

The indoor workout builder lays all of this out by week with a printable cue card for each session. If your treadmill and your outdoor pace do not seem to match, see how to convert outdoor pace to treadmill settings.

Want a plan already worked out for eight finish times from 1:00 to 2:15? See the 15-page pacing pack, $7.

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