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How do you run a personal record in the marathon? In part 1 of this series I shared the first four tips that helped me to my PR of 2h38. I set that time in March 2023 in the Two Rivers marathon. As an over-fifty athlete, I surprised myself that I could still do this. The lessons I learned are shared in this series of three blogs. To get in the mood, here is the summary of the four tips of the first blog.

Summary Tips 1-4

The first tip is to go all in. That means my intent was to explore the edge of my possibilities. This implies – by definition – the risk of falling over the edge. May you not succeed that, no real harm has been done. You are always just one marathon away from your next attempt. Every try enriches your experience. Becoming trainable and staying healthy is tip two. You have to be strong enough to run a fast marathon. In the first blog you can read how stability and functional strength exercises helped me to become trainable. I also worked on my weak link – my back – which increased my resilience.Persoonlijk Record marathon - oefeningen

Building volume and training consistently is the third tip. That is simply what a race of 42.2 kilometers asks of you. By gradually building up your mileage, you can safely increase your trainability (tip 2). Logging miles also trains your heart and lungs and develops your mitochondria so that you can run longer and faster.

The fourth tip is to run a series of races to prepare for your marathon. This develops your ability for running hard tempos runs by training your body and mind. Running races also helps you to build up a frame of reference for what is realistic for your marathon in which you want to run your Personal Record. This actually bridges to Tip 5: the use of algorithms.

Tip 5: Using algorithms for your pacing

To run a Personal Record at the marathon, you must be able to make a realistic estimate of the time you can run. In ‘the past’ that was much more like reading into the tea leaves than it is today. I remember the story of Aad Vink, who enjoyed the status of a legend at my former athletics club CV Energie. Rightly so, because he ran more than 200 marathons, 62 of which sub-three hours. In the 1990s editions of the Rotterdam Marathon, Aad ran as long as he could with the lead group. ‘You looked really great in the first kilometer, Aad!’ was the compliment he received at the club the following week. His wish-is-the-father-of-thought kind of reasoning was that someday, if fate was in his favor, he would find himself in the race where the laws of exercise physiology would lose sight of Aad and he would sustain his crazy 3.00/km first kilometer pace to the finish. I would have wholeheartedly wished Aad such a day. Indeed, a typical Aad Vink marathon was: start as hard as possible. When the inevitable decay comes, you try to limit it as much as possible. You will cross the finish line with this tactic, but not in a time that is representative of your capabilities.

To run a Personal Record on the marathon, it is essential to have a realistic pacing plan. As Johan Cruyff would say: not too hard, and not too slow. The crux of course is: how do you determine the exact speed that will help you achieve your best time? I love data. In addition to the ‘standard data’ that sports watches measure, such as heart rate, speed and cadence, I also measure my wattage while running. I use the Stryd for that. That’s a small sensor that you click between your shoelaces. The device measures your wattage, vertical oscillation, leg spring stiffness and much more biomechanical data. That data is processed in an app. You can also specify goals in the app. In my case: the Two Rivers Marathon. The app then makes a prediction of the time you should be able to walk.

Admittedly, I am critical of the use of algorithms for predicting final times in run races. To run a Personal Record in the marathon you want a reliable prediction of your finish time. The half marathon I ran in February 2023 was not just to physically and mentally get myself ready for the marathon. It also helped me to figure out how to use data to make a realistic prediction. I wanted to set a realistic goal for that half marathon – just like I wanted to do for the marathon.Persoonlijk record marathon Stryd

Based on the training sessions of the previous weeks, I estimated that a time of somewhere in the 1h15-1h16 range was the fasted I could run. The Stryd app predicted 1h14 – plus or minus 1 minute. I consulted with Jan Klein Poelhuis, who was helping me in that race. “If you want to know if that Stryd prediction is right,” he said, “just run by it.” That was exactly the argument I needed. And so it happened. I ended up running 1h13 on that half marathon. A lot faster than I thought I could run. Stryd surprised me positively with the accuracy of it’s forecast.

The accuracy of forecasted time deserves to critical remarks.The first is that the algorithm must be well fed. As with all data models, the principle of garbage in, garbage out applies. The basis for the half marathon prediction was a 10-kilometer race I ran the month before. As far as I’m concerned, that works (even) better than the protocol that Stryd itself has to make race predictions. That protocol involves shorter time periods and thus carries the risk of an anaerobic bias.

The second side note is the prediction of which wattage to run. Stryd recommend to run my half marathon at 380 Watts. The first kilometer I ran exactly that wattage, resulting in an opening kilometer of 3min36. This pace felt too easy, and I accelerated to 3.28/km and 398Watt.

The difference is probably in the shoes. I do all my training runs on ‘normal’ shoes. When I race, I run on ‘cheating shoes’. According to Stryd, that shouldn’t matter. My experience however is that the type of shoes you run on do make a difference. The same goes for the surface on which you do your runs. I ran all my endurance runs outside on asphalt. For my intervals, I used the treadmill. I will not go into this further as it is beyond the scope of this blog.

That half marathon taught me that the Stryd is very helpful in making a realistic prediction of your marathon time. I gratefully used that during the marathon. I’ll get back to how I did that in part three of this series. (Just to be clear: I paid for my Stryd myself and I have no commercial interest whatsoever. It’s just a device that I’m impressed with. Because of it’s qualities, I also use it in Personal Coaching trajectories.

Tip 6a: Do an exercise test

To run a Personal Record on the marathon requires that you optimally train your various energy systems. That requires an understanding of how you produce your energy at different levels of effort. An exercise test  helps to understand your physiology and helps to get more out of your training sessions.

Over the past few years I have administered hundreds exercise tests . Until recently I had not subjected myself to it. I wasn’t training for a race, so why test myself? (This is the official reading. To be honest, I also dread going into the pain cave that an exercise test demands;) Now that I had registered for the Two Rivers marathon, I started applying the method I use in how I train Personal Coaching athletes on myself .

This method consists of three steps. The first step is to do an exercise test. This gives insight into your heart rate and speed zones. The test also provides insight into your metabolic profile. This shows the balance in energy contribution between your aerobic and anaerobic energy management at different intensities. It also provides guidance on your exercise physiological strengths and weaknesses. And what you need to work on to take the next step. (Read this blog for more details on the exercise test and how its results translate into a training schedule).

Tip 6b: Train goal-oriented

The second step is to collect reference data around race pace. On December 18 it was raining cats and dogs. I didn’t feel like getting wet and decided to train indoors, on the treadmill. That gave me the luxury of having my lactate meter within reach. The core of that session was 4x5km at 4.00/km – the pace for a 2h48 marathon. Between each block I took a two minute break during which I did a lactate measurement and fuelled up. After the first 5 km my heart rate was 152 with a lactate value of 2.1 mmol. After the fourth 5km my heart rate had risen to 157 and my lactate to 2.8 mmol. What I saw was I also what I felt: I would not be able to keep this pace for 42.2 km.

Targeted training is the third step. Each workout has a purpose and is neither too hard nor too slow. For each session, you should know which system to train and how to best execute that in training. For my marathon, my goal was to be as efficiently as possible at the 2.0 mmol lactate mark. To reach that goal, up to 90% of my training volume was done in a pace of 6.00 to maximum 4.30/km. Once a week I ran a long race-pace intervals of 15 to 25 km per session at a slightly slower-than-marathon pace: between 4.05 and 3.55/km. The second weekly interval was just below anaerobic threshold – which never went faster than half marathon pace: between 3.36 and 3.25/km. Occasionally, I did a set of two hundreds in 19-20 km/h to maintain my upper speed. I repeated this series of workouts week in, week out. I gradually built my weekly volume, but always within the lines of what my body could handle. Every workout was done in such a way that I was ready for the next workout the next day.

The fourth step is retesting. This allows you to evaluate whether you are becoming better at what you want to improve. On February 3, 2022 I did a similar session as six weeks before: 5x4km in 4.00/km on the treadmill. After the first 4 km, my lactate value was 1.0 mmol and the heart rate was 135. After the last 4 km, the lactate value remained low: 1.3 mmol – with a heart rate of 137. For the entire session, my heart rate and lactate values had hardly any ‘drift’. This was a sign that I was training well-dosed and effectively. It also meant a good boost for self-confidence. I felt what I saw: 4.00/km had become an easy pace for the marathon.

Tip 7: Run on ‘cheating shoes’

‘Cheating shoes’ is how 3in1Sports athletes have coined the so-called ‘fast’ shoes. These are the shoes that have the responsive foam and often also carbon plates that make you run faster. This article by Hans van Dijk and Ron van Megen mentions net time savings between 0.6 and 4%. In December 2022 I bought my first pair of fast shoes. That is indeed very late, but the years before I did not compete. And if I don’t race, I don’t have to wear fast shoes either;)

I am still collecting data to investigate how much time these shoes have saved me. I’m not sure yet, and will come back to this in a future blog. My guesstimate: between 4 and 6 seconds per kilometer. If you multiply these time savings times 42, then you will finish your marathon between 2min48 and 4m12 faster. Other than investing in a new pair of shoes, these time savings are free. If you want to run a personal best on the marathon: race on cheating shoes! That having said, bear in mind that not every fast shoe fits every running style. So get good advice and try different types of shoes to find out which shoe works best for you.

Tip 8: Work towards your optimal race weight

What a shock it was when I stepped off my weighing scale mid-April 2022. The verdict was 84.7 kilos. I didn’t have any marathon plans at the time, but I felt I had to turn the tide of getting heavier. I have approached becoming lighter very simply. Every morning, I weighed myself and write down my weight. Occasionally, I add a compliment – or reprimand – to my weight about how I’d eaten the day before. This provides me direct feedback and has enhanced my understanding of how my food choices throughout the day impact my weight.

On June 7, my digital notebook says: 79.5!!! Including three exclamation marks, as a pat on my own shoulder for encouragement. After quickly losing those first 5 kilo’s, my weight went down much more gradually. On September 21, I weighed in at 78.9 kg. The decision to run the marathon had not yet been made. 

What I have written next is with the understanding that getting lighter and managing weight can become obsessive for some people. That is of course not the intention. Fact is that your weight is very decisive for running a Personal Best on the marathon. The secret of running states that 1% weight loss also means close to 1% faster times. The calculator on the same site allows you to calculate time gains from losing weight. My weight loss of 84kg to 79kg (6%) had already given me a time bonus of 9min30. It is almost impossible to train against healthy weight loss – healthy meaning that you maintain your strength and keep your immune system functioning properly.

Gewicht PR marathonI started to pay extra attention to my weight after I decided to run the Two Rivers marathon. That was early January. If you want to run a Personal Record in the marathon, you simply have to be light. My biggest intervention was to not eat after dinner. Thursday before race Sunday, I weighed in at 76.1 kg. Because I started eating extra carbohydrates on Friday and Saturday (the last two days before the marathon), I gained some weight. ‘In the past’, in my triathlon period, I could easily gain two to three kilos if I increased my carbohydrate intake. For this race, I did not want to give up on my lightness. Therefore, I have employed a rather simple trick: getting low on fibers in the two days before the marathon.

To understand the relation between weight and fuelling your carbohydrates stores, let me expand a bit. Carbo loading means nothing more than filling your glycogen reserves to the maximum. You mainly store glycogen in your liver (largest concentration) and your muscles (largest volume). You can store a maximum of 600-750 grams of carbohydrates. Because each gram of glycogen also binds 2.5-3 grams of water, you can indeed gain 2 tot 2.5 kilos. You can partly compensate by that by minimising your fiber intake for the last two days. Fibers also bind water. Being low on fibers saves you around one kilo. ‘Empty’ intestines also have the advantage of less chance of intestinal complaints during the marathon. All told, the scale stood at 77.2kg on the morning of the race. With full glycogen tanks.

Now that my weight was in order, it came down to Execution on The Day Itself. I will save that for the third and final blog.

To be continued

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