Sub 10 Hour Ironman Training and Racing Pace

I had a moment of inspiration out on my long ride yesterday. Following further discussion of what’s required to go sub 10 at Ironman I was considering issues of pacing. What are the paces needed to manage sub 10 and how they relate to training paces. The apparent disconnect between pace during training and those achieved during racing fascinates me. There’s always a little bit more in the tank on race day.

Is this really true though? I realised I had partial data for the 2007 season when I went sub 10 at Ironman Austria. My bike had an Ergomo so I routinely trained and raced with power. I kept paper records of swim and run training and events throughout the year too. Taking this data I can look at pace and power and perhaps learn more about how I trained for the sub 10 result.

The BIG caveat is this doesn’t tell you how to train for a sub 10 Ironman. It tells you what worked for me in 2007, but without appreciating what happened in 2006 or the exact weekly training structure it’s hard to apply to yourself. It gives guidance and hopefully more to consider if you’re aiming at the sub 10 goal.

If you’re planning a sub 10 Ironman you need to break down the times required. Exact numbers will vary depending on personal strengths and weaknesses; I’ll work off the times I’d consider as an example. Firstly put aside ten minutes to cover transitions and for a small buffer. From there I’d aim at a 1:00 swim, 5:25 bike and a 3:20 marathon to comfortably come under ten. I think that’s reasonably balanced, you might need to adjust times to favour different disciplines.

Knowing these estimates enables you to determine pacing for each stage of the race. It’s theoretical of course, but you can take this to your training and use as a metric for testing and performance. If you can’t ride the pace in an Olympic or Half Ironman then you know that it’s not going to work for an Ironman. On a more positive note perhaps you’ll find the required pace easy – that’s exactly where you want it to be.


For my hypothetical sub 10 Ironman I want a one hour swim. That gives a pace of just under 1:35 per 100m so I need to be able to swim 1:34s, but more importantly I need to hold that over distance. Wetsuits and the draft complicates matters as they’ll normally give you a faster swim so perhaps you could get away with holding 1:38. For recent races I’ve liked tests of ten to twenty 100s on short rest to see if I’m comfortable below 1:35.

Date Event Distance (km) Time Pace (min/100m)
2/3/2007 Welsh Masters 1.5 23:54 1:36
2/3/2007 Welsh Masters 0.2 (Breast Stroke!) 3:21 1:40
2/3/2007 Welsh Masters 0.4 5:54 1:29
9/6/2007 Cerney Lake Swim 3.8 1:05:46 1:44
8/7/2007 Ironman Austria 3.8 59:28 1:34

In 2007 I was actively involved with my local Masters squad and went to some meets. This gives some long course race data for the early part of the season. My 1500m time suggests that I might be around one hour for the swim with the benefits of a wetsuit and draft (but not without). Clearly I had a disastrous time at the open water swim event close to Austria itself. I was a long way off pace and would have eaten into the buffer for my Ironman.

I strongly believe that whilst the Austria swim felt relaxed and I was very lucky. The time was the result of some excellent drafting occurring by chance. With a large field the potential for drafting is huge, but requires good positioning at the swim start. There was nothing strategic about my first Ironman swim though! I happened to start centrally and up the front of the faster swim group and from there got carried along.


Hypothetically I want a 5:25 or an average speed of 33.2km/hour (doesn’t seem fast when you type it). Speed and pace on the bike is heavily course and condition dependent though. I’ve worked with power as my primary means of pacing since late 2006 and used heart rate as a fall back. Ironman is about being as fast and efficient as you can within conservative intensity zones. For sub 10 we’re looking at achieving that speed at a low level of exertion.

Date Event Distance (km) Time Average Power Normalised Power Speed (km/hr)
14/3/2007 Sample threshold interval 1 12.3 20:00 256 255 36.7
7/4/2007 Sample long ride 1 201 7:23 164 193 27.2
28/4/2007 Sample long ride 2 180 6:05 166 190 29.6
20/5/2007 Sample threshold interval 2 12.5 20 248 255 37.3
3/6/2007 Ironman Switzerland 70.3 90 2:38 219 236 28.4
8/7/2007 Ironman Austria 180 5:12 166 187 34.2

One of the surprises of looking back at this data was how low the power was for the Ironman! I weighed about 71kg on race day so less than 2.5W/kg averaged (for reference I’ve averaged 3.2W/kg these days). Taking the sample threshold sets to indicate my FTP was around 255W at the time (sorry data is sketchy back then) I rode Austria at around 65% effort. If anything I was potentially under-performing.

That 65% effort level is the key – at that intensity if I got my nutrition right I’m setting myself up for a good run. I currently race at a higher intensity than that, but I was new to the game then and if your main goal going under ten hours there’s something to be said for holding to that.

I was interested to note that some of my long rides were very comparable to the Ironman effort. This isn’t typical of my training now where the trend I see is normalised power from long training rides as a good indicator of Ironman performance (assuming I’m well rested and putting in some effort on the day).

The important metric is the capacity to perform at the 65-70% effort level whether based off heart rate, power or feel. Other races or some testing training sessions to trial paces in this area are definitely worth using. Outside of this the other focus has to be nailing your nutrition at that work level.


For my 3:20 marathon I’m looking to be running 4:44 min/km (7:37 min/miles) not fast by running standards. The main factor in developing this is running lots. You need good aerobic endurance and conditioning for the Ironman run long before considering speedwork.

I’m aware of arguments favouring speedwork for run economy and efficiency I’d point to how poor this is for most of the field anyway! The problem for most athletes isn’t just about run economy it’s a matter of having the conditioning to maintain good form late in the race. You may improve form on the track, but you only achieve the fitness to sustain it in an Ironman through aerobic conditioning.

If you really feel the need to work on economy and speed I’d have to advise a dedicated run focus for a while. The impact of hard run sessions on training is potentially too high for their return. Frequent running isn’t so tough on the body and as conditioning improves you can increase duration and add hills to progress further.

Date Event Distance (km) Time Pace (min/km)
18/2/2007 Ashford 10K 10 35:37 3:34
12/3/2007 Sample long run 19.5 1:30 4:37
25/3/2007 Reading Half marathon 21.1 1:17:46 3:41
9/4/2007 Sample long run 2 26 2:00 4:37
15/4/2007 Cambridge Duathlon Run 1 7.5 27:27 3:40
15/4/2007 Cambridge Duathlon Run 2 7.5 29:06 3:52
8/7/2007 Ironman Austria 42.2 3:26 4:53

Unfortunately I have less metrics for running. I’ve data logged digitally, though plenty on paper. I work off pace and feel these days so heart rate doesn’t mean much to me, but it would have been useful.

I didn’t have the run I wanted in Austria thanks to a classic combination of pacing and nutritional errors. I didn’t eat enough on the bike or early in the run and set out at three hour marathon shape when I was no where near that fitness. My training diary notes I slowed after 10km, but at 30km the wheels came off with stomach issues and loss of energy. The final 10km were a painful mix of run and walk that cost a lot of time.

In training my long runs were roughly at the Ironman pace I would have wanted (though this wasn’t planned) I was generally running easy at 3:20 marathon pace. What you do in your regular long run is a good indicator of how you can perform in an Ironman marathon. Though these days my long runs tend to be slower than my Ironman pace – I still run at a similar pace to 2007, but I race faster when in form.

Run race and duathlon results give some indication of the run conditioning I’d carried through into my tri career. I wasn’t doing speedwork in 2007, but I was still able to run a lot faster when I raced. Perhaps the fact I had a hard run race or event at least once a month substituted for track sessions. I’d carried through a lot of economy and form from my years of run training (when I had done speedwork). Either way speedwork wasn’t necessary to run a 4:53 min/km paced marathon.

Whilst comparing my training data to the race it’s worth bearing in mind that I wasn’t targeting sub 10. It was my first Ironman so I just wanted to finish (and get a decent time of course!) The idea of sub 10 occurred during the bike and transformed to sub 9:30 for a while on the run. That soon disappeared though when nutrition and pacing reared their heads! I may have some records on that which I’ll have to dig out too.

Whilst this is a little rushed and doesn’t give all the data it could I hope it gives some insight into the kind of training that lead to a sub 10 Ironman first time round. Feel free to ask any questions you have below.

Ironman Training Library

From nutrition to pacing - a collection of CoachCox blog posts focused specifically on Ironman training and racing.


  • Triathlon789

    Great stuff again Russ, keep up the good work!

  • jo

    surely a lot more attention should be given to your choice of course. the may be reassuring in your training and can help while away a few hours when you;re not training (and WHY arn;t you training, may i ask??) but the type of course ,the conditions and how the racing field distributes = esp on the bike – have far more to do with your finish time. There are certain (IM) races where an awesome result may be off 10hrs….and others where sub 10 is merely mediocre. Tends to be dictated by the bike course. Other than swims which are measured short, or damn rough our swim pace is your swim pace. Unless the run is really hilly, or has a lot of turns – what you will run is really determined by the state that you get of the bike in. If you can knock out 5 min k’s in training – and have done enough training the only thing stopping you running a 3:30 is nutrition or having smashed yourself on the bike, so a fast and consistent course with a bit of bunch riding will support a god split on foot. For those who this time barrier is of importance, time might be well-spent researching (and being quick to enter) faster races.

  • I agree course choice is relevant – there are a set of races that make sub-10 easier and a set that make it harder If you choose Lanza for your goal you’re setting yourself a far bigger challenge than Austria. Most people looking to break 10 hours are taking the first step of picking the faster Ironman courses – or at least avoiding the slower ones.

    So assuming an athlete looking to break sub-10 has taken that step then I was basically considering the nature of my training in comparison to the nature of the race – i.e. the intensity and volume of training and racing prior to the Ironman and the intensities sustained in the race.

    As I say looking at my own training for Austria I was in shape to ride a 5:12 at 65% of my threshold – which in turn ensured I got to the run able to run well. I then paced that run badly, running too well initially and paying later for the mistake. Similarly I made nutritional errors on route. I was lucky to have enough buffer to finish sub-10 despite this.

    I think what I took from looking at my 2007 training was that I didn’t do massive hours compared to now. At times I did long rides comparable to my Ironman race effort and then rode the Ironman at a suitable percentage of my threshold to run well. Similarly I ran far less than I’d imagine, but the pace I was running for my long runs was appropriate for a sub-10 target. Again it was a relatively low percentage of what my be considered a threshold pace.

    I guess the point I was getting at is these are factors to look for in training and racing in the lead up in order to have a sense of your potential to break sub-10.

  • I suppose the other thing is that for most people regardless of the course they’re choosing sub-10 is a stretch goal. The group of athletes for whom it’s a matter of just knocking out a certain set of paces is quite small.

    A lot of athletes considering if sub-10 might be possible aren’t just wondering about courses, but also what workload they need to do, what they need to be able to do in training to achieve the goal. Sure a generic answer says so much, but you can suggest metrics. In terms of those paces that you need to knock out and how that relates to some of the training you do. What’s effective, what’s most important and what do you need to be seeing in training to know you’re on course?

    The more detailed problem then is if you’re not at those metrics how do you get there?

  • Triathlon789

    For me, a sub 10 would be a big stretch goal, therefore the course would be of vital importance for me to achieve that goal. Also, as you say Russ, as it would be a stretch goal, then the trainig time available would also be of huge importance; the splits needed for a sub 10 would only be achievable (for me) with a big consistent block of uninterupted training.
    A sub 10 for me is probably just outside of my reach (when you consider family and work comittments), but what a goal to have? For me, I would find it difficult to get out the door (like this morning when it is p#ssing down) unless I had a stretch goal to go for.

  • This is a great report. this will be a great reference to our fellow racer. Thanks for making such a good post.

  • Chris

    Hi Russ

    Great to read this blog. Was particularly interesting to read your section on running training. Seeing as we are looking at a fairly focused winter of running it was good to be reminded that to post a strong IM time you don’t neccessarily need to run that quickly, you just need to be able to hold the pace you set out at.

  • Hey Chris,

    Absolutely the key thing in the Ironman run is having the fitness and endurance to run a reasonable pace the entire way round. Get off the bike fresh enough and then run a race based around a solid aerobic pace. You may look to push later in the run, but you want to avoid imploding by working too hard or eating insufficiently.


  • Excellent.
    What do you think trying your first sub 10 at Ironman France or Switzerland ?


  • I’ve no direct experience of Nice, but the Swiss course is the faster of the two, probably the better option.


  • Twiglet

    Good article Russ.

    Alex, Nice is defo a tougher bike course and a similarly fast run course. I did Nice in 2009 with a bike split of 6:22 compared to 5:42 in Zurich 2011, both with 3:38 marathons…lets not talk about the swim 😉


  • Alex

    A bike split of 5:12 at 166 watts avge power?? I’ve seen a lot of videos from IM Swizterland and it looked to me like a draft fest…but good for you trained hard I assume.

  • Hi Alex,

    I averaged 166W for 5:12 in Austria not Switzerland, I didn’t race with power when I raced Switzerland the next year. There was drafting at both, I saw it first hand, and no, I didn’t participate in it. In Austria I had a good aero position, it’s a fast course and as data from other athletes that raced there confirms, it’s short. I’m pretty happy to stand by that time on that wattage without the aid of drafting.

    You can see some data from 3 athletes at last year’s Ironman Austria here. Athlete A did 5:14, averaging 205W or 2.6W/kg; athlete B did just under 5:00, averaging 187W or 2.8W/kg; and athlete C did 5:27, averaging 176W or 2.7W/kg. Aero positions, distribution of efforts, FTP all varied between them, but a wide variety of average powers producing quite different times on the conditions of the day. 10W difference in average accounted for almost 30 minutes difference in time with one athlete having a bad day, spending too long above his FTP early and not so long in the aero position later. There’s also my analysis of Nick Baldwin’s ride at Kona last year, 4:53 on the bike at an average power of 199W (3.1W/kg).

    There is plenty of drafting in Euro Ironman, but then I’ve seen it in Ironmans round the world, US, Australia, everywhere. It’s an unfortunate fact of the sport. I trained hard in 2007 when I raced Austria, as I did in the years before and have done in the years since. I’ve never actively drafted in a race, have dropped back when over taken and stayed out of draft zones to the best of my ability. But you can only take my word on that.


  • AJ

    I’ve just found this when googling for what it would take to go sub 10 on my first Ironman, and this may be the best resource with actual data out there on the net!

    The most insightful for me however, were your 10k, and half marathon times in that buildup. They are a pretty objective level of fitness (courses are much the same, and measured properly. What they say is you need a formidable level of fitness! I’m about am minute shy on the half marathon now at just under 1:19, so a sub-10 is probably out of reach given my poor swimming, unless I up the effort level a lot!

  • AJ,

    Thanks for the feedback and glad you found this useful. It’s quite an old post now, but remains relevant, perhaps I should revisit with some more data based on a few of the athletes I’ve coached to sub 10.

    Picking markers of sub 10 performance is difficult – course and conditions do play a role both in the lead up events and the Ironman itself. That said I think there are some fair indicators that you can look for in terms of run speed, bike power and swim speed. I’d say a 1:19 half puts your run in the right region so it really becomes a question of where your swim and bike are at, both in terms of individual ability to do the time and efficiency to ensure you can run well at the end.

    You mention poor swimming and this is a good point which I’ve discussed with one or two athletes I coach. Return on investment in swimming is typically poorer than for either biking or running, but if you have a slow swim you will need to have a strong bike and run to compensate in order to go sub 10. I wrote about this when I analysed one of my athlete’s performances in Florida last year. Here’s a graph I posted in that showing the swim times of sub 10 athletes versus the entire field:

    Comparison of swim times for sub 10 athletes and the entire field at Ironman Florida 2012

    It’s something to consider in the balance of training and with a run in the right region there may be benefits to greater focus on the bike or the swim.

    Thanks for reading,


  • Spencer

    I completed nice this year.the bike is tough and it was extremely hot in the looking to compete in a quicker ironman but it seems the quicker ones book up quickly!if anyone is intending on doing nice you’ll have a great experience as its a great event!