Criss-cross intervals: 20 continuous minutes in five 4-minute waves, with power stepping up from 95 to 105% of FTP and back down again. A 45-minute session for intermediate riders already comfortable with split threshold work.
| Target | Zone | Time | FTP 200 W | FTP 250 W | FTP 300 W |
|---|---|---|---|---|---|
| 103–105% | 4Threshold | 5 min | 206–210 W | 258–263 W | 309–315 W |
| 100–101% | 4Threshold | 5 min | 200–202 W | 250–253 W | 300–303 W |
| 97–98% | 4Threshold | 5 min | 194–196 W | 243–245 W | 291–294 W |
| 95–96% | 4Threshold | 5 min | 190–192 W | 238–240 W | 285–288 W |
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Holding a fixed power for 20 minutes is mostly a test of patience. The criss-cross adds control: you move constantly from just under your threshold to just over it, in 30-second steps, without ever dropping to recovery pace. The top of each wave takes you past the point where fatigue builds up; the way down brings you back just under it, but high enough that you barely recover.
That's exactly what rolling roads or a turn on the front of a group ask of you: up a bit, down a bit, never easing off. So the session trains threshold and the knack of pacing around it. No study has tested it: like most threshold sessions, it comes from coaching practice.
Intermediate riders who've already done several split threshold sessions, such as cruise intervals or threshold 2 × 20, and want some variety. An up-to-date FTP is essential: with only a few per cent between steps, a wrong FTP muddles the whole session.
Once a week at most, alternating with a 2 × 20 or over-unders, never on top of them. Leave an easy day before and after, and avoid the day before a race. To progress, extend the block to 25 then 30 minutes, or ride two 20-minute blocks with a proper recovery between.
5′ at 45–55% FTP + 5′ at 56–65% FTP + 5′ at 66–75% FTP
15 minutes building from 45 to 75% of FTP, in 5-minute steps. Use the last few minutes to set up your turbo and check the steps are showing properly.
5 × 4′ between 95 and 105% FTP
20 minutes non-stop, in five 4-minute waves. Each wave climbs in 30-second steps, from 95–96% to 97–98% then 100–101%, holds 1 minute at the top at 103–105%, then steps back down in reverse. For an FTP of 250 W, you move between 238–240 W and 258–263 W. In ERG mode, the turbo handles the changes; outside, pick a flat or barely rolling route and make each change smoothly, without surges.
10′ at 40–55% FTP
10 very easy minutes at 40–55% of FTP. It's your first real recovery since the block started: drink, and let your breathing settle.
The tops of the waves are hard, and the way down offers no rest: at 95%, you're still working. The first waves feel easy, the fourth starts to bite, the fifth takes all your concentration. If you like intervals with a proper break, you'll soon miss them. Guide: 8 out of 10 at the top of each wave.
Over-unders switch in sharp jumps, 2 minutes under threshold and 1 minute over, in three blocks with recovery. The criss-cross rises and falls in small steps, in a single 20-minute block. One teaches you to absorb a surge, the other to pace.
Outside, it's tempting to jump straight to 103–105%. You lose the gradual build that's the point of the session, and reach the top more tired than planned. Go up one step at a time.
Easing below 95% on the low phases turns the session into ordinary intervals. The bottom of each wave is still at threshold: that's deliberate.
It looks playful, but it's 20 minutes around your FTP. It replaces a threshold session in your week rather than joining it.
The 'Criss-Cross Threshold' session described by coach Gale Bernhardt, recommended after several split interval sessions. The source describes it by heart rate, from the bottom of zone 4 to the top of zone 5a in Joe Friel's system, with rises and falls of about 2 minutes. The conversion to 95 to 105% of FTP, the 30-second steps that make up each rise, the warm-up and the cool-down are Wattson choices. It's a coaching source with no dedicated study. Bottom line: good confidence in the structure, moderate in the conversion to power.
From 95 to 105% of FTP, in 30-second steps. For an FTP of 200 W, that's 190 to 210 W; for 250 W, 238 to 263 W; for 300 W, 285 to 315 W. The minute at the top of each wave is ridden at 103–105%; the rest sits between 95 and 101%.
How the changes happen. Over-unders switch in sharp jumps: 2 minutes at 94–96%, 1 minute at 104–106%, in three 12-minute blocks with recovery between. The criss-cross rises and falls in 30-second steps, in a single 20-minute block with no break. The first trains surges, the second pacing.
Yes, on a flat or barely rolling road, with a power meter. Show the current step on your head unit and make every change smoothly. A drag for the top of the wave helps, but avoid roads with junctions: stopping breaks the 20-minute block, and continuity is the whole point.
Because it has 35 steps in 20 minutes. In ERG mode, the turbo sets the resistance at every change and all you do is hold your cadence. Without ERG, you can follow the steps through your gears, but precision drops, especially between 97 and 101%.
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