This past spring, I switched to racing on trails, aiming for events that would take me about 4-5 hours, as this duration is quite enjoyable at the moment, sitting approximately at my first threshold (i.e., I’m putting some effort). In particular, I raced the following races near home:
Chianti Marathon Trail, 46 km +1900m, 95th / 1400, 9th age group.
Tuscany Crossing, 52 km +1500m, 16th / 500, 3rd age group.
My last race report was after the Winschoten 50 km, 6 months ago, which was arguably my best road race, running five nearly identical laps at the limit of my ability. While my A goal remains a road race (did I tell you about Passatore yet?), I’ve changed my mindset and goals since last summer, and I’m gradually shifting to racing trails. I think this is partially due to having reached my limits (and the goals I had set for myself) on the road - and therefore being less motivated - and partially due to the way racing trails adds layers of complexity that challenge me (technical terrain, steepness, fueling, temperature, etc.) while also amplifying aspects of exercise that I value (being in nature, the focus on perceived effort, being more aware and in tune with my body, variability in effort and race strategy, being less obsessed by hitting an exact pace every kilometer, etc.).
Just like for Winschoten, this blog is not really about the race, as much as it is about the training, which I think is where I might have something more interesting to say, given my average performance level. In particular, I’ve prepared quite differently from the past, given how I’ve grown as an athlete and the different demands of the race with respect to road running.
Hence, I will go through the reasoning behind my long-term periodization, data on metabolic flexibility, how I’ve addressed muscular limiters with strength training and hard running, the use of cross-training and passive heat, race-day fueling, and more.
I’ll add a bit of race analysis in terms of heart rate and pacing as well, because that’s relevant too.
Big Picture: What’s Missing and Where Can I Improve?
Some context here is needed. I love to run the whole day, but not beyond that. Say 4-10 hours, which could be on roads or trails, and ideally include a good scenery. I dislike running in loops, especially for long events, and I’ve learned somewhat surprisingly that one of my strengths is climbing, so a fair amount of that is something I now enjoy and chase, as long as it’s runnable (i.e. not in the mountains). We are talking ultratrail, say 40-60 km with ~1000-2000m of vertical gain up to Passatore (road, 100km of mostly rolling hills).
I’ve mentioned in the past how the work I’ve done on metabolic flexibility has improved greatly my durability for these events, from a metabolic point of view, of course. Durability is multifaceted, and while now I can rely a lot more on fat oxidation, save glycogen, limit depletion, delay fatigue, and race personal bests, there is one more aspect of durability (which we could define as our ability to maintain a desired output for a looong time), limiting my performance in these events, i.e., muscular durability.
Having 1) a relatively high VO2max for my performance level (~65 ml/min/kg) 2) the ability to hold an intensity quite close to it for about 80’ minutes (i.e. a strong Threshold as well), 3) pathetic running economy (~230 ml/min/km), 4) a highly flexible metabolism able to burn over 1 gram of fat per minute above race intensity, and 5) having trained high volume for many years, I believe there is very little margin for me to race faster by addressing any of these 5 aspects (my VO2max does not change anymore, my threshold is already as good as it gets given my ceiling, my economy also seems not to move - unless I wear supershoes, 5-10% better at that point - my fat oxidation is basically elite level because of the perfect mix of training volume, avocados and genetics, and I cannot possibly train more than ~20 hours per week without burning out). What’s left out in the context of improving performance for the events I’m interested in is muscular durability, which is ‘so bad’ (frequent cramps and other difficulties) that it feels like even a reasonable improvement could lead to meaningful race performance gains.
So that’s what it is: to get better at the races I enjoy, I needed to condition my muscles to be more durable.
How do we do that? Below is the approach I’ve used in the past 6-7 months.
Periodization: Building Muscular Durability
As it often happens in training, especially in the era of social media and algorithmic engagement, different schools of thought tend to get polarized, so that we have the ones claiming you only have to run, and the ones claiming you can do it all in the gym, when it comes to improving muscular durability (or muscular endurance).
Fortunately, I am not a religious man, and I have friends on both sides of this ‘fight’. Also fortunately, my training is not a scientific study where you need to isolate a single component, and so I can throw lots of things in the mix and only care about the outcome (am I more durable?). The ingredients might change (forms of cross-training, running workouts, etc.), depending on a number of factors (neural capacity was a big one for me in these months, while it wasn’t in the previous build), which is the beauty of the art of training and coaching (get coached?).
Needless to say, I’ve used both the gym and hard running workouts to improve my muscular durability. In particular, this was my reasoning:
Gym: it should be possible to improve the maximal strength of my (leg) muscles. By doing so, I might be able to delay fatigue when racing at a relatively lower percentage of my (then higher) maximal capacity. Think maximal strength.
Gym: it should be possible to improve the durability of my (leg) muscles by training their endurance capacity. Think strength endurance, just more training or more stress for specific muscles.
Run: it should be possible to do the two things above with more volume of hard running on hills. Yes, running hills is a good strength workout, but when you are very well conditioned, train a lot, run a lot of vert on a weekly basis, and still have muscular durability issues, then the principle of supercompensation still applies: you have to get beyond your capacity to get better. This means that ‘running hills’ isn’t good enough, but you might have to run harder and steeper. Cook those muscles (sometimes!).
In terms of periodization, I’ve always done little in the gym in the past, or used it more for health (mixed sessions upper and lower body without a specific focus or periodization or anything that would cause fatigue during running), while this time I decided to give the gym the number one priority in my training. It was a bit of a bet and certainly the biggest change in my training in years, in particular because I did not have the capacity to just add it, but to do so, I had to drop completely any hard running in my training for several weeks.
Hence, the high-level periodization of these past months:
October: closing racing season.
Capacity. November - mid-December: High Volume of easy running (peak week 180km), 2 x week in the gym.
Maximal Strength. mid-December - February: bringing back my Threshold, 1 x week in the gym (sometimes 2 x, but mostly unable to do it well that frequently).
Endurance. March: Tempo for Race Specificity and fitness, 1 x week gym maintenance.
I’ve also done 2 x extra core sessions in the gym, those were always the same and always carried out across the 6 months, not periodized, as they don’t create collateral damage (hence won’t be discussed below).
In the next section, we look at this periodization in more detail.
Details: Strength in the Gym and Hard Running Workouts
October: closing racing season
After Winschoten in September (50 km +0m, road), I raced Big Rock (47 km +1000m, trail) and Trail del Cinghiale (43 km +2600m, trail), underperforming in both races. At Big Rock I misjudged my ability to sustain a certain intensity on the trails. As I was coming from summer in Amsterdam, I thought I could race closer to Winschoten intensity, and faded badly at 30 km. At Trail del Cinghiale, I learned my lesson and paced well, but all my (muscular) limits were really obvious; I cramped after 20km already in both adductors, and in general struggled a lot in a race where you basically never run (too steep and technical for me). Again, coming from summer in the lowlands, that’s okay, but the whole experience reinforced the need to address this specific performance limiter, and that training volume alone wasn’t cutting it for me (I had done multiple 150km+ weeks with plenty of vert in that build).
Capacity. November - mid-December: High Volume of easy running, 2 x week in the gym
In November, I planned my Strength training as follows:
Base Block: develop basic capacity for something new. I kept it very simple to begin with, 4-6 exercises (Squat(x1-2), Lunge(x1-2), Hinge, Calf). To load the exercises I used a weighted vest for practical reasons (it works for all exercises, I can increase the weight easily, etc.). For this block, I used 3-4 sets of ~8 reps with moderate weight.
In terms of running, I had to pause high-intensity workouts because I never had the required freshness (due to the gym). This break lasted about 5 weeks, then in mid-December I was able to run hard again (while maintaining 2 x gym sessions).
Maximal Strength. mid-December - February: bringing back my Threshold
Between mid-December and January, the gym was the same, but I also did 6 Threshold sessions (one per week tops, sometimes one every 2 weeks):
25’, rolling hills (<3% grade)
2 x 12’, one hard downhill, one hard uphill (6-12% grade)
3 x 10’ indoor, flat
2 x 12’ uphill on trails (10-20% grade)
20’ + 2 x 10’ indoor, flat
2 x 12’ uphill (6-12% grade)
After this month, my threshold was as good as it gets for me (about 3’45”/km), despite the previous block without any running intensity. The lesson there is that our strengths come back really fast; there’s no need to stress about them.
In terms of gym work:
Support Block: develop ‘maximal’ strength. Similar structure to the base block, with 4-6 exercises (Squat(x1-2), Lunge(x1-2), Hinge, Calf) but with higher weight and lower reps (I used a bit more than 20% of my body weight for the vest, 3-4 sets of 4-6 reps).
Endurance. March: Tempo for Race Specificity and Fitness, 1 x week gym maintenance
Phase three was about training hard and for long (what I call Tempo in my training prescription) which of course is all about specificity for long (but not extremely long) events as well as pushing race fitness even higher. In this phase, I had to drop the gym to 1/week as the long and hard runs would leave me too tired for 2 sessions per week. The gym done well was still the highest priority, but training hard was more and more important given that we are getting closer to racing season.
Running workouts in this phase, all Tempo, over a month and a half more or less:
25 km at marathon pace on rolling hills (4’14”/km)
2 x 30’ of road climbing (6-10% grade)
2 x 40’ of road climbing and descending (4-8%)
2 x 20’ of climbing on trails (15-25%)
For both Threshold and Tempo sessions, I used hills a lot, and often went on trails to increase the steepness of climbs, while sporadically pushing hard also on the downhills, to add stress on the muscles and improve their durability.
Gym work:
Specific Block: strength endurance. Similar structure with 4-6 exercises (Squat(x1-2), Lunge(x1-2), Hinge, Calf) but with lower weight and more reps, e.g., 3-4 sets of 12-15 reps.
Here are all the key workouts I’ve done in these 5 months between races, which is only 14 (8 Threshold and 5 Tempo + 1 race simulation for Passatore). Quality sessions done well and at the right time:
Between races: High Volume Block
I’ve discussed elsewhere how I thrive on volume and keep my taper really short, hence since in this phase I felt structurally solid (i.e. no niggles or other reasons to limit volume), I took the time I needed to feel good again after Chianti, and then pushed volume near my limit before doing another short taper ahead of Tuscany Crossing.
Eventually both races were raced at the same intensity, and took me a very similar time, reflecting what was my capacity those months.
Other training notes
During the training blocks up to Chianti, I’ve added plenty of vert in my weeks, with a reduction in January because the weather was quite poor and I couldn’t get on the trails (which were just rivers of mud), and as such, I trained on the road or indoors that month.
I’ve also had the usual niggles, and managed them with the bike (see below). I was always able to do what I thought mattered the most: gym, hard running workouts and long runs, but I had to often reduce weekly volume by replacing easy runs with easy rides, until after Chianti, when I started to be able to tolerate more load (up to 235 km/week after Tuscany Crossing).
Most importantly, the weekly vert was ‘more focused’ than in the past. I tried to run faster on average, outside of workouts, for specific climbs or descents. The goal was to add intensity just enough to add muscular stress that could lead to positive adaptations without compromising the rest of my training. Thin line, of course, but that’s what pushing our limits is about - wherever they are.
Also note how little hard running was needed to be the best version of myself: maximum one hard run per week. This is not a universal truth, it’s just my capacity. Better athletes can do more, but copying their training won’t do us any good if we cannot assimilate the work. Always ask yourslef, do I have the capacity to do ____ (whatever is hip today)? Or should I just stick to the basics and do less, more consistently, until my capacity has increased? Often, the answer is the latter. For me personally, in terms of intensity, I kept it very simple these past 6 months: I did a block of threshold to raise my capacity for sessions that will be both high volume and high intensity (Tempo work), and then I did those sessions, which resemble a race or are harder than a race (but a bit shorter), eventually getting me ready for the big day. Nothing particularly fancy, but everything carefully planned.
Cross-training: The Bike and Passive Heat
My original plan for these 6 months was not to bike, if anything, just because winter cycling isn’t really my thing. That being said, when my body doesn’t cooperate (e.g., running niggles), I’m quick at this point to switch risky runs (which might turn a niggle into an actual injury) for rides, and as such, I ended up cycling 3-9 hours per week most weeks since January:
All my cycling was low intensity. This was the exact opposite of what I did July-September, when almost all my cycling was high intensity. Main reason: this time I had no neural capacity to go hard on the bike once the gym and hard running were done well, and those were way more important for my goals.
Running was modulated accordingly, with lower volume when I had more niggles (and therefore biked more):
As a result, this year I trained more time (210 hours, run+bike), but ran less than any other year since 2021 (I ran 1200 km up to March 24th, 75-80% of what I had done in the past).
Total load, if that’s a thing:
An important takeaway here is that the quality of what we do matters a lot. It seems obvious, but especially when thinking about trail running and ultra distances, it’s hard not to start thinking that volume is what matters the most. Volume matters, of course, but there’s a point when the quality of our work, either running or in the gym, is worth more than large volumes of running done with less intent (‘pascolate’, a technical term I learned from my colleagues at Destination Unknown).
Once I run about 100-120 km in a week, adding some high-quality running and a good session in the gym is worth more than increasing that running volume by shuffling around many hours. There are more muscle fibers to use and gains to make when we have the capacity to tolerate non-easy running.
In a way, I was glad to be forced to run less (by the various niggles), as it allowed me to test something otherwise I would have unlikely tested: focusing on key sessions, keeping volume moderate (as opposed to very high), and then using the bike more, to avoid physical issues that are so common when running more.
Again, durability is more about quality and the intent of each session than overall running volume.
You can see below that my weekly running volume is quite a bit lower than last year (+19% time), but includes plenty of very long runs with more intentional climbing and descending (elevation gain is indeed much higher despite less running, +38% in meters), sometimes with quality (hard climbs and hard downhills, to work both on fitness and muscular durability). Overall training volume is higher (+28% time) because of cycling. The data below does not include the block between Chianti and Tuscany Crossing.
Passive heat
Big fan of passive heat.
I started years ago in preparation for the Florence furnace (i.e., 3pm race start at the end of May for Passatore), but then it grew on me, and I started doing it basically every day when I’m in Italy. Since then, quite a few studies have shown interesting results on the benefits of passive heat also for racing in temperate environments, hence why not (a reason not to would be that all stress matters, so if adding passive heat makes you sleep poorly, train poorly, recover poorly, etc. - you might have more to lose by adding it, but if it doesn’t, then I think it can be an incredible tool). As someone who has always struggled in the heat, I feel like a bit of chronic exposure can do me good, hence the strategy.
My protocol is 20-22’ after training pretty much daily, maintaining temperature at about 42C.
Adaptation: How am I Responding?
You probably know I find it particularly fascinating to try to capture how we respond to the various things we put ourselves through.
One way to do so, is through the lens of heart rate variability (HRV), see my guide here, and best practices on how to measure it, here (spoiler: not with wearables).
From a nervous system point of view, it’s been a good couple of months, with things rather stable apart from when I had a hip issue and maybe some associated inflammation. Reintroducing intensity in December-January worked well(I maintaned stability), and similarly, peaking with volume as well as introducing long and hard tempo runs (which, together with the previous threshold block, would be the 'hardest to digest’, from a nervous system point of view), led to no suppressions in HRV, which I took as a good sign that I was balancing load well, recovery well, and assimilating the work well.
With the introduction of the bike, maybe at a certain point I overcooked it, as I started routinely training more than 3 hours per day, or at least I reached the limit of my capacity to sustain a certain load (which at that point was over 20 hours / week of training for 5 weeks in a row).
We can see this in a sustained suppression that I could not turn around even with a taper in which I trained 3 hours in 6 days, even though I suspect race nerves got in there as well in the last week, which is very typical of me (the ‘passion for stress’ is rooted in an inability to deal with it well).
Heart rate data shows nothing noteworthy, as it tends to be a less sensitive marker of stress, apart from race morning, when things went bananas:
All things considered, I think I pushed it a bit too much with overall volume when I was also doing long tempo runs, we are talking very high volumes + very long and hard runs. I am a regular person in the great scheme of athletic performance after all, not an outlier.
My thinking was that I was going to force myself to almost stop training for 2 weeks (1 week of taper, race at Chianti, then one week of recovery, so basically 2 very easy weeks with a big effort in the middle), hence I pushed the volume a bit more than I would have otherwise done, given the context.
No issues eventually with the race, where I felt strong and fresh, but maybe this is what we are seeing in the data. Between races we can see a good pattern with stability in HRV data, and a positive trend even when pushing the load quite high (about 200 km for the week):
and then another heart rate peak on race day, I clearly have my issues with race nerves:
Testing: VO2max, Thresholds, Metabolic Flexibility
As you might know, I’ve put together a small private lab which I use for myself and the athletes I coach whenever they can get to Brisighella, which allowed me to test a few things during this whole process.
In particular, I was curious to see the impact of stopping high intensity running on my fresh state physiology (VO2max and Thresholds, VT1/VT2) as well as how those parameters would change when reintroducing high intensity running and during this training build, which was quite different from my previous ones.
VO2max and Thresholds
I first tested in September after Winschoten, hence arguably in my best shape. Then I tested again after my ~5 weeks without high-intensity running. During this phase, I reintroduced passive heat training, which was missing in summer as I don’t have a bathtub in Amsterdam. Hence, this latter factor might have contributed to VO2max staying the same between these two tests. On the other hand, both my thresholds were slightly worse. This is in line with a recent study showing that passive heat improves VO2max but doesn’t improve Threshold.
I then tested again mid-February, when I had already done all my threshold training and some tempo runs, which led to (maybe surprisingly) some of my best testing: VO2max was again exactly the same, but vVO2max (the velocity reached) was 1km/h faster, and both my thresholds were higher (in terms of velocity). Hence, despite this type of fresh state profiling capturing nothing of durability (which was the focus of my training), I had a better profile than back in September:
It could be that the strength work enabled greater capacity for uphill climbing and, as such, a greater training stimulus on my hard sessions, which led to greater improvements also in my fresh state profile. Speculations.
Metabolic Flexibility
My little project of last year.
I think at this point I’ve understood quite well how it all works, which took me a while, and lots of testing (fresh state, before / after long runs, while changing macros in my daily diet for several days or weeks, etc.). Some learning here, and a podcast with Niki Micallef where I think I finally articulated it decently, here.
During these 6 months my diet has been quite heavily periodized (the way I discussed here), which means typically I do 2-3 days per week in which I stay quite low carb (e.g. omelette for breakfast, greek yogurt, nuts, peanut butter and berries as snacks, a salad with avocado and some protein for lunch, more vegetables and lean meat or fish for dinner), 2 days in which I stay high(er) in carbs (i.e. the same as the low carb day but replacing the low carb breakfast with oats and fruit, then during the day more fruit and possibly pasta either for dinner or lunch), and 2-3 days in which I stay moderate (which means low but less anal about it). The periodization is driven by training of course, and since I tend to do 1 hard run per week, and maybe a longer run with some quality, I end up doing 2 higher carb days to support those, and stay lower for the rest of the week (and easy training). This mix works wonderfully for me, and I also enjoy it very much at this point.
Before Chianti, I did a short check starting from an easy jog to the highest intensities I would think to touch on a race like this (that is, just around my first threshold, as going harder would not be sustainable for the time it takes me to run that distance. Plus, my first threshold is pretty high at this point and I normally train way below it, in Zone 1).
The data showed what I had seen a few times in the previous months, i.e., I’m burning 1 gram of fat per minute, with no degradation with increased intensity (a steep drop would then happen if I had kept increasing intensity up to the second Threshold):
The same can be seen also below:
The last image shows how the higher the fat oxidation, the lower carbohydrate burning becomes, but at the same time, fat oxidation is limited in its maximum value and can only help so much when you increase intensity / power output.
What does this mean in practical terms for the fueling of athletes of different levels?
This is a key consideration to understand. It explains why an elite athlete can still need plenty of carbohydrates per hour despite having a very high fat oxidation rate (their fat oxidation in absolute terms is not unlike mine, but their power output is much higher, meaning they burn more carbohydrates at what is still a ‘low’ or ultramarathon intensity for them, despite high efficiency).
Somewhat paradoxically, a less good athlete would benefit even more from having high fat oxidation rates because they could sustain their power output indefinitely at their race intensity, and could therefore have more freedom (than the elite) in terms of how to deal with their race nutrition.
I repeated these tests also before Tuscany Crossing, with very similar results given that my diet and training hadn’t changed:
Some data from the last test:
Body mass = 73 kg. Estimated usable glycogen at full capacity: ~550 g
CHO oxidation at race pace (average between the last two stages shown in the image): 1.7 g/min, given about 1 gram/minute of fat oxidation at race pace.
Total carbohydrate need = 1.7 g/min x 300 min (5 hours race) = ~510 grams
Exogenous carbohydrate need given stored glycogen and oxidative capacity: 510 grams (CHO oxidation rate at race pace) - 550 grams (stored in the body) = -40 grams, i.e., 0 grams needed of exogenous carbohydrates. Obviously, I’m messing with you, but see the nutrition section below to see how all of this plays a role.
Durability: Is it Getting Somewhere?
Million-dollar question.
Despite the positive results in my lab testing, it remained a challenge to understand if the whole point of these 6 months (i.e., improving muscular durability) was getting somewhere or not, before the first race.
Durability is something we work on, but we put it to the test only on race day, when the system is stressed to its limit. It is not something we can easily see improving day by day or in our hard workouts or even in our longer runs, at least not in the same way we can see progress during, e.g., a marathon build or when progressing from a state of limited or moderate training to high volume training.
Personally, I found this quite challenging mentally. I mean, I was totally fine, but still, I was wondering, is this helping me make another breakthrough, or should I do something else? At the end of the day, I want to get to Faenza before midnight, IYKYK.
Thinking about these months, here are some cues that I noticed during this process, and that gave me confidence that something positive was happening:
After 5 weeks of no intensity, I ran all out for 5 km uphill, at what we could consider Threshold or a bit above Threshold intensity. I ran a personal best on that occasion for a segment that I had raced many times before, feeling like, for once, the limit was my cardiorespiratory system and not my legs’ inability to generate the required power against gravity. It was a good first sign that gym work was transferring to running (a strong point against the ones arguing for ‘only running’, something you wouldn’t argue in any other sport).
On the bike, I could ride out of the saddle on climbs for ‘a long time’, while normally it’d be a 30-second activity for me before my legs would start burning. I found this interesting as ‘the work was transferring’ even if not running related.
On my runs, I could run faster on the downhills, without even trying. It was like what was a normal subjective feeling of going downhill easy while ‘saving the legs’, now was reset to a different level, which meant running quicker. The difference wasn’t enormous, but enough to notice.
On my runs, I could climb better when the grade went higher than 10%. I couldn’t really notice much difference on 6-8% grades - where I was already efficient and running well earlier - but 2 months in, I started seeing I could run 20% grades and stay in zone 1, which I was never able to do before.
As you can see, none of these are direct assessments of durability, and I did not really see particular differences during my long and easy runs, but there were a number of indications that made me think maybe I was getting somewhere with the plan I put together for this year.
The final answer was going to be at Chianti, the first race of the season.
The Races: Planning and Execution
Tapering
For both events I kept going with my training until the Sunday prior to the race, and then tapered heavily for a week, which meant one day off, and a few days of pretending to run (Thursday to Saturday on the race course with friends).
Given the whole focus of these 6 months, I decided also not to do any hard running but to do one strength session instead, as a final ‘quality stimulus’ before the race. Race week before Chianti:
Race week before Tuscany Crossing:
Pacing and race intensity
For both events, I planned to race just below my first threshold for most of the time, getting around it or slightly above on the climbs, but then making sure I’d get my heart rate a bit lower on the downhills or flatter parts. All of this was driven by perceived effort of course, but with a heart rate cap as a limiter to make sure I wasn’t overcooking myself too early. I was expecting a 5-hour effort for both races (given that one is longer but has less vert), or maybe 4h 45’ on a very good day, hence the intensity needed to be managed accordingly.
While grade-adjusted pace as its limits (type of terrain of course matters and can’t be accounted for, i.e., how technical it is), we can see the pacing was as good as it gets for Chianti:
My heart rate at Chianti was very stable. I expected more drift, but we were extremely lucky with the weather, which was a bit chilly, but not humid, and even when the sun came out, there was the right amount of breeze not to overheat. Again, just very lucky on that front.
Eventually, my average heart rate was 85% of my recent maximal heart rate, hence I think I’ve managed it very well this time, combining perceived effort and a heart rate cap (and of course, dropping the damn ego since the start) to stay around my first threshold, which after many years of good training, has reached a relatively high intensity.
Somewhat similarly for Tuscany Crossing:
which was, however, a month later and quite a bit warmer in the second half of the race, leading to higher cardiac drift (and other issues I’ll discuss in the nutrition session below):
Environmental conditions aside, I’ve felt pretty much the same for both races, and kept the intensity where I thought I could maintain it for the required time. I’ve also put together the plots below to show heart rate distributions across race quarters, which I think is quite informative to show us potential issues with pacing.
Here is Chianti:
For Tuscany Crossing, we have a similar situation, but with a higher heart rate in the last quarter, due to higher temperatures. I was able to maintain the same power output but definitely struggled more and felt that I had to dig quite a bit more, mentally, in order not to fade in the last part of the race. The higher internal load was definitely perceived as such:
For context, before is a race that I paced poorly, which shows the typical profile you’ll find in most athletes that start too enthusiastic, so to speak:
Fueling
As discussed earlier, race fueling should depend on 1) your power output (the higher your capacity to produce a certain output, the more carbohydrate you will burn, regardless of your fat oxidation, which can only account for so much). This is why elite athletes’ intake should be higher than my own, 2) your metabolic flexibility in relation to the duration of the event. The more fat you can burn, the less glycogen you burn, and therefore the less likely you are to hit the wall (that’s right, you don’t hit the wall because of not eating enough carbohydrates, but you do because your body can’t function without burning carbohydrates due to poor metabolic flexibility and poor fat oxidation rates, resulting in quick depletion of glycogen - since no amount of carbohydrate intake can spare muscle glycogen - and only liver glycogen is impacted by carbohydrate intake during exercise, see Matt Carpenter’s excellent video on the topic). Now, I added “in relation to the duration of the event” because it’s overly simplistic to ignore the fact that for 3-5 hours, we can certainly do very well with limited carbohydrate intake, but if you start skipping meals because you are running the whole day, then a higher hourly intake is important regardless of the macros. At that point it’s just calories, and we need the calories for such a long event, we cannot only focus on the next point, which is 3) maintaining blood glucose levels, or yet another imporant reason why we need a certain (very low) level of carbohydrate intake even when we are very metabolically flexible and when the race is short enought for glycogen stores to last. Finally, we should remember that 4) the brain likes carbs, and even mouth rinsing improves performance, hence frequent sips might be a good idea even if the overall rate is not particularly high.
Put all of that together, and for Chianti, I know that given my race intensity (85% of my maximal heart rate, and a bit over 12 km/h grade-adjusted speed), and my fat oxidation rates at those intensities (i.e. 1 gram/minute), plus full glycogen stores given the limited training of that week plus 2-3 days of high-carb intake prior to the race, I can last about 5-6 hours without any intake at all (what? yes, true story).
However, this doesn’t account for maintaining blood glucose stability (which requires 10-15 g/carbohydrate per hour), and brain-mediated performance effects of carbohydrate intake (again, see research on carbohydrate mouth rinsing), hence in training, or previous races of similar duration, including some of my best events since becoming metabolically flexible, I gravitated around ~30 grams/hour, which allowed me to perform at my best without gastrointenstinal problems (or with limited but somewhat manageable gastrointenstinal problems).
At Chianti I decided to experiment more as I’m still experiencing issues with gels, and as such, I’ve been drinking carbohydrate solutions to see if I could do better in terms of gastrointestinal discomfort (the reasoning is rather simple, if I sip every few minutes, my gastrointestinal system can deal with a little food each time, as opposed to ‘a lot’ of food in a single go). Eventually, I had about 80g + 80g in 2 flasks, plus 1 gel with caffeine (100mg) and 30g of carbohydrate (+200 mg sodium). Half an hour to the finish, as fatigue was more present, and for once I had no nausea or any other gastrointestinal issues (which might mean drinking carbs is working better for me), I decided to take another gel, hence I had about 220g CHO total in 4 hours and a half, or about 50 g/hour, which sits more or less where recommendations were before most people went nuts (e.g., providing intake rates without accounting for power output, which seems the unfortunate norm).
At Tuscany Crossing, I opted for the exact same strategy I had used at Chianti, but eventually had ~40 g of CHO/hour: 2 flasks (90 g each), and one gel (30 g + 100 mg caffeine). I had planned slightly more, but had to adjust on the go as the warmer day made it a bit more challenging; I got the usual nausea, and eventually decided to skip a few gels. Knowing that your metabolism can handle a lot of different situations - not only chronic high-carb intake - helps a lot when you need to make adjustments because of unforeseen issues. Less fuel, but no drop in pace or other issues, because of metabolic flexibility.
To recap, given my power output and metabolism (fat oxidation rates), I can run 4-5 hours at moderate intensity (as in a race like Chianti or Tuscany Crossing) without running out of glycogen, hence the intake is there to maintain blood sugar, delay hunger, and for other neural benefits. More carbohydrate at that point means an increased likelihood of more gastrointestinal distress (no, vomiting during a race is not normal), without any performance gains. Running faster might benefit from higher intake, but I am not capable of running faster for that long, regardless of what I eat (obviously!).
That’s a Wrap
These two races were a lot of fun.
Never in an ultramarathon I felt like my muscles could sustain what the rest of my body is capable of, allowing me to race well, while being considerate, but still being able to push, overtake, and just have some fun instead of simply having to manage cramps and muscular issues for half of the race until the finish line, for what is typically just a very long mental exercise for me.
Needless to say, I like it more this way. Everything needs to be managed, and it’s always a thin line when it comes to an ultramarathon raced at the limits of our abilities, but the muscular durability I was trying to improve has indeed improved and allowed me to live one of my best running days. Two races out of two done well seems a good signal.
In the past, I used a more standard and generic build towards ultramarathons, in which the focus was on getting as fit as possible, and then trying to extend that fitness (e.g., prepare for a half-marathon, then a marathon, then an ultra, during a 6-month build). While the approach makes sense, and was what I needed while still developing my capacity over those distances, this was no longer what I needed now to make another step forward. In particular, in the past two years, I went quite deep into my limiters to find more room for improvement, first with metabolic flexibility (and dietary changes) and now with muscular durability (by combining gym sessions and hard workouts on steep hills).
Eventually, I ran very similar races. The level in the two events is quite different, some of the best runners in the world were at Chianti, while Tuscany Crossing is a smaller and lower profile event. Obviously, at my level, I can only race for myself, and the way I felt during the race (i.e., strong) is what I was really chasing with this training block. This being said, the competitive aspect does remain an important part of the enjoyment of racing for me, and I look forward to a few more of these days.
Chianti Marathon Trail, 46 km +1900m, 95th / 1400, 9th age group.
Tuscany Crossing, 52 km +1500m, 16th / 500, 3rd age group.
Thank you for reading, and happy training!
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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 is a certified ultrarunning coach.
Marco has published more than 50 papers and patents at the intersection between physiology, health, technology, and human performance.
He is co-founder of HRV4Training, endurance coach at Destination Unknown, advisor at Oura, guest lecturer at VU Amsterdam, and editor for IEEE Pervasive Computing Magazine. He loves running.
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Hi Marco, Thank you so much for sharing all this information. I’m not a runner—my passion is cycling, and I face similar challenges to yours during my events (Alpine bike marathons). I often deal with cramps, and of course, nutrition is a big factor. Strength training hasn’t yielded the results I’d hoped for so far. I’m going to try your approach of reducing my weight. I generally follow a low-carb diet and only use carbs strategically before and during hard or long workouts. That works very well for me. I’m interested in how you do your carb loading before a race to ensure your muscle glycogen stores are full. Before I went low-carb, I used to consume 8–12 g/kg of body weight for 3 days straight. That’s unimaginable now! And have you ever measured how it affects your fat oxidation rate? I’d also be interested to know how you’d fuel yourself during a high-volume training camp or a stage race without disrupting your fat oxidation rate? Thank you very much and all the best
Hi Marco, thank you again for sharing your trials ! I found very interesting that you added strength training very progressively and even heavy sessions are very controlled, far from some papers (I think of Ronnestad paper where the squats are on the very heavy side with low rep and high percentage of 1RM). I think 20% of load is not too much and sufficient to create adaptations. When you say squat x1-2, what do you mean : if x2, you did 6-8 sets instead of x3-4 sets in x1 squat ? Last question, during phase 3, when you say lower weight, how much in comparison of phase 2 ? Thanks a lot !