If you’re busy and missing sessions, protect the key ones first. Across 86 four-week blocks from 27 of my athletes, blocks where they hit at least 80% of their key sessions progressed 93% of the time. Below 50%, it was 24%. I’m Mark Bowstead, an Auckland triathlon coach and former pro (2012 to 2020), and most of the people I coach are fitting this around a full-time job.
What counts as a key session
It depends on the athlete’s history. Start simple: a key session is one with a bit of quality in it, so anything above zone 2.
If someone is coming in with almost no base, a steady zone 2 ride can be the key session too. The way I tell is the step up. If your normal ride is an hour and this one is an hour and a half, that’s a key session. Same with the run: you normally run an hour, this week it’s an hour 20, that long run is the key one.
Swimming’s harder to call. For me it’s the one with some quality in it.
What the data says
I coach in four-week blocks. Before each block starts I set the one thing it has to move, and a measure for it. If the block is about aerobic endurance, for example, the measure might be a long steady ride where heart rate stays within about 5% of where it started for the same power (that drift is called decoupling). At the end of the block I look at it against what the athlete actually did, and whether that measure moved. That’s what “progressed” means below.
Here’s the full set, 86 blocks closed between 30 June and 6 October 2026:
| Key sessions hit | Blocks | Blocks that progressed |
|---|---|---|
| 80% or more | 45 | 93% |
| 50 to 79% | 23 | 57% |
| Under 50% | 17 | 24% |
Completing every session mattered less than you’d think. Blocks with 90% or more of all sessions done progressed 89% of the time, and blocks under 75% still progressed 55% of the time. So if you can only get some of the week done, the key sessions are where the progress is.
Overall my athletes completed 2,298 of 2,851 planned sessions (81%) and 273 of 362 key sessions (75%).
Why sessions actually get missed
When a session was missed and we knew why, work and life were behind 41% of them. Illness was 24% and injury 13%. Being too tired from training was only 5%. And every now and then I get a session wrong for someone, so I own that and fix it in the next block.
That doesn’t surprise me. The people I coach are driven. Put a plan in front of them and they’ll do their best to finish it. The misses come from things outside their control, and the numbers show how often that happens. Which is the whole reason a plan has to bend around your week.
When your week falls apart
Here’s what I tell athletes when work blows up or a kid gets sick.
- Keep at least one quality session in each sport. Drop the rest first.
- Cut the session with the most hassle around it. If the swim means driving to the pool, getting changed and rushing back, and that’s stressing you out, that one goes.
- Keep the running ticking over. A gap means a jump when you come back, and running is where the injuries come from.
- If you’re a weak swimmer, hold on to the feel for the water. If you’re coming back from a run injury, keep the run progression going.
Most weeks, when time is tight, the first thing to go is the easy bike hours.
The Saturday brick is usually the safest session of the week. There’s more time, and family or friends can often help out if a kid’s sick.
What I don’t want is you cramming a session on the trainer at 9pm because you missed it earlier. If that’s not your normal, it’s a fast way to be sick in a few days. Illness was the second biggest reason sessions were missed in this data. I’d rather we move things around and keep the week normal, because consistency is what moves you forward.
How to read these numbers
A few honest caveats. “Progressed” is my judgement at the end of each block review, against the measure set at the start. Fitness tests are tracked separately. And most of these blocks (57 of 86) were base training over the NZ winter.
Common questions
How many missed sessions is too many in a triathlon training block? In my athletes’ data, blocks where 80% or more of key sessions were done progressed 93% of the time, even when other sessions were missed. Under half the key sessions, it dropped to 24%. Count the key sessions first.
Which triathlon session should I skip when I’m short on time? Usually the easy bike hours. Keep one quality session per sport, keep the running consistent, and drop the session with the most hassle around it, like a pool trip that’s stressing you out.
Should I make up a missed session later in the day? Not if it means a 9pm trainer session that isn’t part of your normal routine. That’s how athletes get sick. Move things around within a normal week instead.
Why do busy athletes miss training sessions? In 86 of my athletes’ blocks, work and life caused 41% of misses with a known reason, illness 24% and injury 13%. Fatigue from training was 5%.
If you’re fitting IRONMAN or 70.3 training around a job and want a plan that moves when your week does, see how my coaching works. For more on making the hours work, read training for an IRONMAN with a full-time job and IRONMAN New Zealand on 10 hours a week. More about Mark Bowstead.
