Best vs Worst 70.3 Workouts, Ranked by Science

After 20 years of triathlon experience and over 15 years of coaching, I've tried numerous sessions and countless workouts. Some make you faster, some make you stronger, and some are a waste of time. Some you just don't know are working, because you saw someone else doing them. If that's you, there are plenty of other people thinking the same thing.

So I've broken down 12 sessions for a 70.3 (half Ironman): four swim, four bike and four run. I'm not going to tell you exactly how to do each one. I'm going to highlight what it's good for, who it's good for, and whether I rank it as a waste of time or right up there for performance. I'll also back it up with a couple of science reviews alongside my own views.

There are numerous experts and high-level triathlon coaches with their own beliefs. I've cherry-picked over the years from people I really respect, tried a lot of it, worked a few things out myself, and with years of application realised what works and what doesn't: some of the fluff, and some of the detail.

The rankings at a glance

• Swim: 45 minutes of drills (low). Five to 12 minutes of drills in the warm-up (good). 1.9 km continuous (high, in the specificity phase). Repeated 50 m sprints with long rest (low). 400s with paddles and pull buoy (high, in the general conditioning phase).
• Bike: 3 to 5 minute VO2 intervals (high). 40/20s (moderate to high). Hill repetitions (high, probably the best workout there is for a triathlete). A 5 to 6 hour zone 1 ride (low).
• Run: a 2.5 to 3.5 hour long easy run (low). 10 by 200 m sprints (low for a 70.3). 3 by 10 minutes at threshold (high). Aqua jogging with a belt (moderate to high).

The Swim: Four Sessions Ranked

1. Forty-five minutes of drills: low ranking

Should triathletes spend 45 minutes on drills? Absolutely a waste of time. Does that mean you shouldn't do any drills? No. It's low-ranked if you spend that long on them, because we're not competitive pool swimmers.

Five to 12 minutes of drills in your warm-up is really good for setting the tone and activation, and triathletes should definitely do that. Not every session, though: make sure it counts, and I'd probably only use two or three drills. That's enough.

2. A continuous 3.8 km or 1.9 km swim: high ranking in the specificity phase

This is highly advantageous in the specificity phase. As you get closer to your event, you want to be conditioned for the demands of the event: 3.8 km for an Ironman, and 1.9 km for a 70.3. Most swim sets are broken up into 100s, 200s and 300s. We can do interval training and break up the boredom, but most importantly it makes 2 to 3 km go by quite quickly, because no one really wants to get in a pool and swim 3.8 km. I rank it really high in the specificity phase.

3. Repeated 10 to 12 by 50 m efforts with 2 to 4 minutes rest: low ranking

The key there is the 2 to 4 minutes of rest. Why is it a no? Because triathlon is not an anaerobic sport. We're not trying to be sprinters. You could argue that sprint work is great for neuromuscular control and muscle activation, but I'm talking about the 85% of the triathlon field, which is probably you watching this, doing high-level anaerobic work with long rest, which takes forever. It's for sprinters. We are aerobic engines. Yes, we do need a little bit of speed here and there, trickled into the swim, bike and run, but repeated 50 m sprints with long rest get a low ranking.

4. 400s with paddles and pull buoy: high ranking in general conditioning

This is clearly a strength session. It carries a higher risk of shoulder injury if you're new to the sport, but if you build into it, it's high-ranked for me in the general conditioning phase. As you get close to the event, lengthen those repetitions to 600s and 800s if you can tolerate it.

Start with two to three 400s and build up to 6 to 10 by 400 m with about 40 seconds recovery. It's all done aerobically, so you're not out of breath. It's a big bang for your buck: arms dead, legs fresh, ready to go. You'll find huge gains when you put the wetsuit on.

The Bike: Four Sessions Ranked

Most of us enjoy the bike loads because it's outdoors, and it's the longest portion of your triathlon whatever the distance. Here are the four sessions for a 70.3.

1. Three to 5 minute VO2 intervals with equal rest: high ranking

This could be three or four repetitions, up to six. It's ranked highly and is quite specific for triathlon, working above your threshold power, and you can sprinkle it all year round depending on the time of year. It's especially important for older athletes over 40.

One overlooked point: you can slice those intervals into shorter amounts if you aren't conditioned to handle 3 minutes straight off the bat. Instead of three minutes, do three by one minute with equal rest, building up to the minimum standard of three minutes, for about 18 minutes of total work. That will give you big gains in your threshold, which is directly correlated to 70.3 performance.

2. 40/20s, ten times: moderate to high ranking

That's 40 seconds on, 20 seconds rest, hitting around 90% of your VO2 max on each repetition. Why is it important? You build up a high level of carbon dioxide with the short recovery, and you have to do quite a few reps, at least 10 to 12, to get that CO2 build-up in the bloodstream. It has a direct correlation to your top end.

I'd put it as moderate to high, because a high VO2 max is not necessarily a key indicator of performance for a 70.3 athlete, but it is helpful, especially if that's the limiting factor in your threshold. Most people do a lot of this in the winter, because it's not specific to your race demands 12 weeks out. Give it a go in the winter and see how your FTP improves: one to two sets of 10 by 40/20.

3. Hill repetitions: high ranking

Probably the best workout there is for a triathlete. It's strength training in disguise on your bike. This could be 3 to 5 minute efforts on any incline. You're working a big gear and building huge muscular strength, in an upright position, which gives a big bang for your buck for time trialling, because that's what we're doing. You can build up to 15 to 20 minute reps.

Be aware that you increase the chance of knee injury because of the force through the kneecap. But it's the biggest bang for your buck, ranked high. Do it all year round for huge returns.

4. A five to 6 hour zone 1 long ride: low ranking

In terms of time efficiency, this isn't a great return for your bang for your buck. Most people ride it really easy, at around 100 to 140 watts. You're just getting junk miles in the saddle. You're better off doing 2 to 3 hours with real, specific structure. Zone 1 power belongs in the recovery portions of that, rather than the whole ride.

I rank it low. That doesn't mean I'm against long bike rides. That wasn't the workout; that was a zone 1 bike ride. For how to structure a week around the key sessions, read Train Smarter, Not Longer.

The Run: Four Sessions Ranked

A lot of triathletes struggle with the run and blame their lack of run training. Often that's due to the bike being structured really poorly, so think about that. Here are four run sessions.

1. A 2.5 to 3.5 hour long easy run: low ranking

Controversial, but hear me out. It builds loads of fatigue, which increases the chance of injury. We know we get quite tight as triathletes from cycling, sitting and a general lack of mobility, so building extra fatigue on top of that just decreases your resilience and opens a huge can of worms for injury.

You're better off building the frequency in your week and shortening your runs. And if you need time on your feet to build up the distance for a 70.3, you're better off adding some walking on really hilly terrain, to build up really good run-specific muscles with low impact.

2. Ten by 200 m sprints on the track: low ranking

This is low-ranked for Ironman athletes, and not a very high ranking at all for a 70.3 athlete. You're better off doing something like 10 by 800 m with a 200 m jog, at your half-marathon pace or slightly above, to develop durability and resilience for what's coming. Build it up to 20 by 800 m for the more experienced, as long as you have a very good foundation phase.

200 m sprints aren't specific to your race goal of 21 km. Just because the fast runners are doing the speed work doesn't mean you need to do it.

3. Three by 10 minutes of threshold work: high ranking

This is at 97 to 102% of your threshold pace, and it has a high ranking for Ironman and specifically for 70.3. Why? Because it works at around your lactate threshold, which is exactly where you spend a lot of the time in a half Ironman. If 3 by 10 minutes is too much to start with, slice it up into 6 by 5 minutes or 4 by 8 minutes. It builds tolerance and a really good aerobic foundation, and it helps buffer lactate, which is ultimately what we're trying to improve for endurance athletes going for a 70.3.

It comes at a cost, especially over 40. It does increase the chance of injury, it's pretty tiring, and there's a high glycogen carbohydrate cost. So bear that in mind, whatever age you are. There are papers to back this one up, and you'll have heard of double threshold days.

4. Aqua jogging with a running belt: moderate to high ranking

You're not going to believe this one, but it's highly underrated, whether you're injured or not. It's an optional, zero-load workout of pure run mechanics with no gravity. It's 20 to 30 minutes continuous in the deep end of a pool, up and down. Yes, you might feel a bit of an idiot, but it improves your economy and efficiency, because you have to move the whole body, and your core gets activated. You can slice it into intervals.

Try it in addition to your third run of the week, for low impact while you're swimming. You can stay on in the pool if it's deep enough, and a belt costs very little for a huge return on investment. I'd put it at moderate to high. I've definitely tried it myself, injured and not injured, and some of the top runners in the world complement their run training with aqua jogging.

Frequently Asked Questions

Final Thoughts: Context Is Key

Like anything in triathlon training, context is key, so take that into consideration. Where you are in your triathlon journey matters more than which session is trending. Common sense prevails if you're a beginner: build the base first, then get into the detail.

If you'd like help with that, whether it's a chat or speaking to one of our coaches about how to get ready for your next 70.3, get in touch. To see how these sessions fit into a full plan, read Build Your Own Half Ironman (70.3) Training Plan.