Discover more from Marco Altini’s Substack
5 things I've done differently this year while preparing for a 100 km ultramarathon
training, racing, fueling, managing weight and heat acclimation
Last year I attempted the 100 km del Passatore, the oldest ultramarathon in Italy, which goes from Florence to Faenza (a town near where I’m from).
I must say, as much as I like running for many hours, I am drawn to this race mostly because of my personal history. My father ran it 43 years ago. Then as a child, I used to go with him to see his friends competing for a top 10 finish. I have many memories of evenings and nights spent between Marradi and Faenza, supporting runners battling this somewhat crazy challenge.
As my love for the sport kept growing over the years, I finally signed up and decided to give it a go last year.
Eventually, I had a rough race in the heat and ended up in a hospital with massive cramps. This forced break triggered some self-reflection and renewed interest in trying to get back into a different type of training and shape, as well as to address a few things differently, as I think I made some novice mistakes.
In particular, here are 5 aspects that I tackled differently this year:
Training: focus on the best fitness possible more than volume.
Racing: more frequent racing to also improve my approach to the race (psychologically).
Fueling better: running an ultra is dramatically different from running short distances or even a marathon, it took me a while to find the right formula
Managing weight: a delicate topic, but I let it slip a bit last year while this year I have been quite focused.
Heat acclimation: there are many ways to reach the same goals, it seems, and some of them might be better than others.
Let’s look at this in a bit more detail.
Thanks for reading my Substack! Subscribe for free to receive new posts and support my work.
During the preparation for Passatore, I was obsessed with volume. Probably a naive mistake of first-timers at such a long distance. I ran very consistently, 6 days per week, 130-140 km per week, for many months. However, I was also getting slower and slower, accumulating niggles, and being unable to do proper workouts.
This year, I still wanted to keep up a decent volume, as I know I benefit from it, but without sacrificing the intensity. It was clear at this point that just running more easy miles wasn’t working for me, and that more isn’t always better (a hard concept to get behind at times). In other words:
Fitness before volume.
This year I trained harder, but as a result, I have also trained less (hours or kilometers). I still went for some long adventures, as this is something I like regardless of what race I’m preparing for, but I always gave priority to hard workouts (short or long intervals, tempo runs, etc. - depending on the training phase). Then, I tried to run as much as I could between hard workouts, without compromising my ability to perform them.
Both volume and intensity matter, but I find it easier to accumulate volume (you just have to run after all), while intensity requires adequate health, planning, recovery, etc. - and is the first thing to go when we have a setback. I tried to make sure I wasn’t slipping this time.
Keeping up the intensity got me fitter while improving my physiology in a number of ways that will all be beneficial for the ultra (e.g. lower cost of running at any intensity) - running for long gets easier when training hard, assuming plenty of easy volume is present as well.
I think this new approach has worked well so far, as I raced PRs on every distance (10km, half marathon, marathon), and went beyond my most optimistic expectations at times (it’s easy when you are very realistic, or as others call it, pessimistic).
I will try to keep it up in the future.
Last year I felt very stressed before the race. Funny how these things play in our heads even though they really don’t matter (at least in my case, as a nobody in the running world).
This year I wanted to get better psychologically, and also take the opportunity to combine the change in training I mentioned above and add a good high-intensity stimulus with higher frequency (i.e. race more).
In July, I started adding a race to my calendar every month, typically a short one not to disrupt training. I ended up racing a few Parkruns in Amsterdam (5k), where I volunteer, two 10 km races, two half marathons, and two marathons during the year.
I think I have slowly reached my goal, as I slept only 2 hours before the Ravenna marathon back in November, and almost 6 hours before the Manchester marathon in April :)
Whatever pressure I am putting on myself, it seems I am handling it better now. Racing while getting faster has also been a lot of fun of course, and I look forward to keeping this up too.
I will spare you my rants about tapering for now, but you can certainly race more frequently without making any major adjustments to your training. Train well and account for recovery on a weekly basis, instead of digging an enormous hole that requires a month of recovery before a race.
Running an ultramarathon is dramatically different from running short distances or even a marathon. Last year I read as much as I could, and fortunately, I had Daniel to help me out as well. However, I still struggled to find the right setup, what to eat, how frequently, etc. - I think this just comes down to experimenting a lot, and maybe I didn’t experiment enough before.
Fast forward one year, and lots more experimenting, and I now feel quite confident with different strategies for different races and distances, even though my intake is still on the low side.
I currently alternate gels and solid food, plus take electrolyte pills (these ones from precision hydration). Every 6 km, I either take a gel or a Clif bar, and a pill. The pills have been a really great way to manage electrolytes, as I really dislike the flavor of tabs that go in water, and I have struggled in the past just to keep drinking during hot days. This way I get the intake I need and just drink plain water.
I have some backup options, but I think I can manage to run ~10 hours will only these two types of food without hating them too much. I then drink at thirst based on what’s available on the course or what I carry. This is a bit more frequent than I’d do for a marathon when I take 1 gel every 7 km. More frequent intake gives me GI distress, but this might change in the future with more GI training. In training, I normally use similar foods that are however cheaper than “engineered food” (pain au chocolat being an absolute favorite).
Since I’ve started to be more methodical, I have experienced fewer lows, and I often finish very long runs without being particularly hungry, which never happened before. I was also fortunate to have a good chat with Aitor during a run in Barcelona. Aitor is a great expert on the topic and did lots of interesting work showing how muscular damage is reduced when carbs intake is higher (paper here), another reason why I try to eat more during my runs, especially when out for many hours as it happens when preparing a ultra.
Step by step, figuring this out.
During the last few years, I had gained some weight. The ultramarathon made things worse as I let my diet slip a bit with the added volume, a typical mistake (e.g. you run a lot and think can eat a lot, but it doesn’t really work that way).
This is not an easy topic, but given that the goal was still the long distance, and that I am a very inefficient runner, I wanted to lose some weight to give myself a better chance (see some of the math later). I had done this before, so I was in familiar territory. Please note that this blog is just about my experience, and is in no way advice or something you should be following.
In terms of diet, I mostly eat a Mediterranean diet, as I was fortunate to be born where this is the norm. To lose weight, I stopped snacking entirely and started eating only three times per day, breakfast at 6-7 am, lunch at noon (after training), then dinner at 7 pm. For lunch, I have mostly salads with stuff (beans, fish, avocados, eggs, nuts, cheese, potatoes, etc.). For dinner, normally I eat more vegetables, and then meat, fish or legumes. I don’t drink any alcohol. I normally have pasta once per week, same for pizza. Otherwise, very little or no ultra-processed foods outside of breakfast. I do have a large breakfast as I am often hungry from the caloric deficit of the previous day. I try not to eat any crap unless I’m on a long run (or it’s breakfast!).
Following this process, I lost again about 10.5 kg or 23 pounds, eventually going a bit lower than I should have, and later settled around 66-67 kg.
Given the caloric deficit that lasted for a few months and the simultaneous hard training, I tried to fuel my training more. If I was hungry or just a bit down, I would eat more during training, and eat the same during the day. In my experience, training makes it easier to understand quickly if I am undereating, as I’d notice right away when not feeling good during a run, and then I could correct the course (i.e. eat more). This worked for me as I was able to perform consistently better and lose weight. My guess is that my high metabolism, something I pay the price for during a marathon or ultra, helps me a lot in weight management: it is very easy for me to lose weight quickly. I’d probably rather choose to be able to run a decent marathon, but we play the cards we are dealt.
Above is a before/after pic, on the left side, just before the 100 km del Passatore, I was 75 kg (165 pounds), for a BMI of 23.7. On the right end side, just before the Vila-Seca Half Marathon, I was 64.5 kg (142 pounds), for a BMI of 20.4. During the year I fluctuate a bit, probably part of it is just seasonality, but when I went a bit lower I felt like I was getting sluggish and not performing well. I believe that my optimal is probably around 66-66.5 kg, with lower weight bringing more downsides than upsides.
Dieting is a complex topic, please seek the advice of a professional if you’d like to make changes in your diet, weight, or training. Do not copy random people online.
Fueling + weight
Fueling and weight, together with the energy cost of running, come together when trying to figure out how much I need to eat for a given distance.
In 2022, at a hypothetical ultramarathon pace of 5’40”/km, I would consume almost 900 kcals/hour. At this intensity, I would consume about 480-530 kcal/hour of carbohydrates, which means 5000-5300 kcal for the race. Now let’s say I have full glycogen stores (e.g. 2000 kcals), 1 gram of carbs has 4 calories, so if I need another 3300 kcals, I need to ingest about 825 grams of carbs. Over 10 hours, that’s 80+ grams/hour of carbs for 330 kcals/hour, which is a lot more than what I can eat.
In 2023, at the same intensity, my consumption is now 775 kcals/hour, for a total of 4000-4500. At full glycogen stores, I need another ~2500 kcals, and therefore about 625 grams of carbs. Over 9-10 hours, that’s 60-65 grams/hour of carbs. We are now getting close to what I can ingest.
The math here is obviously flawed and oversimplified, but you get the point: weight, running economy, and fueling all matter, and I have tried to work on them by 1) running a lot and running hard, which improve economy 2) fueling more 3) managing my weight better.
The main unknown for this race is the heat. As the race is the last weekend of May, it is not necessarily crazy hot. In fact, last year was one of the hottest race days in the past 15 editions, and I am secretly hoping we’ll get a good day this time.
However, a little extra preparation probably is a good idea. Last year I opted for training in the heat (i.e. active strategy). Training in the heat meant that I had to limit a lot what I could do and that I eventually trained poorly over the last 2 weeks before the race when the weather got warmer. Additionally, as the race is during a period in which days are getting warmer and warmer, training in the heat means you are always trying to catch up with changes in temperature, which is not ideal.
This year, I opted for a passive strategy: the hot tub. The science on the topic is quite fascinating (check out Jason Koop’s book and podcast for a lot of great resources about the topic). Long story short, sauna or hot baths can give you the same benefit you get from training in the heat, without messing with your training as much.
I have started a simple protocol similar to what Jason covers in his material, which includes 2 weeks farther away from the event, 5 days per week, 20 minutes at 40 degrees Celsius, and another week closer to the event.
I will also do some active acclimation as we get closer to the race when the weather changes, but I will keep training hard earlier in the morning this time.
What I didn’t change
A few words also about what I did not change this year.
Prioritize training: there’s always a lot of extra to do for each one of us. It makes little sense to postpone training because I have to e.g. work, or do another endless task. Training is time-constrained. Once I have done it, there are typically another 20–23 hours in the day. Hence, training has a very high priority in my day.
Training frequency: I kept running only 6 days per week no matter how great I felt. I think this is really what has kept me (almost) injury-free more than anything. Given the muscular issues I have, combined with a tendency to overdo things, forcing myself not to run one day per week is probably the best thing I’ve ever done for my long-term training health.
Training execution: it took me forever to understand that training is not racing and that digging really deep each workout is a recipe for disaster. I try to go hard in my workouts but always finish feeling like there is something left. I did mess this up again in February / March and paid for it, but I hope I am slowly learning this lesson.
Other forms of training: I maintained strength training and plyometrics twice per week. In general, I think that as long as they don’t compromise training, there might be more to gain than to lose by doing these. I do plyometrics on the same day I do hard workouts (but later in the evening) so that I do not have to sacrifice other days. Whenever possible, I try tun trails and hills at least 2–3 times per week, I find that this makes me stronger, breaking the monotony of the impact on flat asphalt, which often leads to overuse injuries for me.
We’ll find out soon enough if all the changes will be beneficial, only a month to the race.
Most importantly, let’s hope for some clouds on race day!
Marco holds a PhD cum laude in applied machine learning, a M.Sc. cum laude in computer science engineering, and a M.Sc. cum laude in human movement sciences and high-performance coaching.
He has published more than 50 papers and patents at the intersection between physiology, health, technology, and human performance.
Thanks for reading my Substack! Subscribe for free to receive new posts and support my work.