Running 100km is no joke.  So you’ve conquered a few marathon-sized events and are intrigued by the notion of going even further.  Let’s look at the best ways to prepare and train for running 100km – and what to expect.

100km Ultramarathon – How To Train and Run

You can’t just extrapolate a 42km training plan for to cover the longer distance (maybe you could, but it’d take over your life).  In reality, you have to condition your body to get used to long hours on your feet, while not over-training. 

If you wish you can skip ahead to the 100km training plan and advice.

Here’s some practical ways you can prepare yourself for this mammoth task:

 1. Time on your feet

This is paramount – more important than speed or miles.  It’s also the biggest commitment you’ll have to give for your 100km preparation.  Your body has to get used to being on your feet for hours on end, so it holds up well come race day.  There’s no set plan here, but doing a few runs that are 50% of your planned 100km time is recommended.  This can mean committing serious chunks of your life (weekends) to running.  

 2. Body strengthening for 100km 

An 100km run is all about endurance, and muscular strength makes you an endurance animal.  Many runners can get by with marathon-length runs by doing only running training.  But once you are on your legs for several hours at a time, having some core strength really helps you keep your form and fuels your endurance.   Remember – your whole body is active while running, not just your legs.  I highly recommend doing cross training a couple of times per week, focussing on the upper body.  If you only have time for one cross-training session, focus on your legs with lunges, squats and stretching  – your body will thank you when you’re 10hrs into the race.  This was one of the key principles that allowed me to make the leap from 42km to 100km in one race – I focussed on strengthening my body rather than just adding more miles to my run training.

 3. Long runs

Just like marathon prep, you should be factoring in one long, slow run every weekend.  As a minimum, you want to have completed at least one 50km before your 100km.  If you are taking things seriously, you want to have covered 70-80km once, and done several 50kms.  Remember to build up to these in a structured way, rather than going out one weekend and doubling your longest run mileage just to get the run under your belt.  The trade-off here is balancing the increase in mileage with not getting injuried (and finding the time to squeeze in all the training).

Another worthwhile training technique is back-to-backs.  This is running two long runs on consecutive days.  This technique gets your body used to running on tired legs.

 4. Tapering for a 100km

Tapering is the age-old marathon training technique of letting your training peak 4 weeks before your race and gradually backing off.  It’s a nice rule of thumb that means you’ve given yourself plenty of time for preparation. Tapering minimises the risk of injury prior to the race and means you should arrive at the start line in the best possible condition.  However, you’ll often find that it’s harder to apply such a rigid structure to ultra-marathon training. Many seasoned ultra-runners barely taper at all – they might just relax a bit more in the week leading up to the event.

Your taper length should therefore be determined by how well conditioned you body is.  If you’ve only been distance running for a few months, it is worth having a 2-4 week taper before your 100km.  This means doing your longest training run in the weeks before the race, then gradually reducing the level of training as race day approaches.

100km, guide, preparation, race to the stones

5. Pick an achievable 100km

If you’re looking for your first 100km, do some research and find one that is relatively flat, in a comfortable climate and well-supported.  Don’t start by adding things like heat, humidity or hyenas.  That race through the jungle / desert / lava flow will be there next year!   The last thing you want to do is to commit to a huge race and DNF because you weren’t prepared enough – this will just discourage you from going again.

“it’s not a sprint marathon, it’s an marathon ultra-marathon

 6. Exertion during the race

If you find yourself having to push yourself in the first 30-40km of a 100km, you’re going too fast.  It’s natural that as you get fatigued, your body stiffens and tires and you have to force through a bit of pain – but this is different from just standard exertion.  Your training should have got you to the stage where you can run at a comfortable pace for hours with little strain.  During shorter races like marathons you can push your body beyond this comfortable pace, but in 100km races if you feel yourself going too hard you really have to dial it back.  Always bear in mind how far you have left to go, and how your body feels.

 7. Pacing and Splits for 100km 

The ideal 100km run is arguably one that has equal splits (a consistent pace throughout).  As races get longer, it becomes harder to regulate a steady pace – especially when you are venturing into untouched territory regarding mileage.  Your legs get tired and begin to cramp, your energy levels sag and psychologically it’s easy to lose focus.  Therefore run at a pace you feel comfortable, it should be a pace you feel is very achievable.   Much like the 4hr mark in a marathon, the 12hr mark is seen as a nice ‘benchmark’ for 100km runners.  But – don’t get sucked in by trying to meet other people’s ideas of expectations.  Run your own race, have a pace / target time in mind before you begin, and be adaptable!

100km Training Plan

Here is the 100km 26 week training plan for you to enjoy, customise, and stick on your wall.

As I’ve noted above, it’s impossible to be too prescriptive.  Different runners have different starting ability levels, and their bodies adapt at different speeds to new training plans.  Some people need more rest, others less.  So take this training plan as a starting point  – don’t be afraid to adjust it in places.   The main thing you need to focus on is getting in the hours on your feet – and not getting injured.

You will probably also be interested in the more holistic and practical tips I give in my blog How I Ran My First 100km – Race To The Stones – showing how I comfortably completed the race in 11hrs 39 mins with what would be considered a ‘minimal’ training regime.

100km, training, running, guide

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