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Power analysis in marathon racing

Sebastian Jayne XCO XCM Marathon MTB Power analysis

For this past weekend, I decided to book in a double header with an XCO race on Saturday and the Saarschleifen Half Marathon on Sunday. The XCO was my main focus but with the Vaude Trans Schwarzwald stage race fast approaching, I wanted to see how my body would react to hard racing days back to back. My XCO race on Saturday went well compared to my last race in the Czech Republic. My power averaged almost 40w higher and I seemed to fix whatever happened last time but I was still a little rusty. But let’s get onto Sunday and thanks to my Stages power meter, have a look at some power!

With the XCO race finishing at 6pm Saturday and the marathon starting at 10:30am, I didn’t have a whole lot of time to recover. After some dinner and protein from Pure Edge it was to bed and after about 3 hours of buzzing around waiting for the caffeine gels to wear off it was time to sleep! I only managed about 5 hours of sleep all up which wasn’t ideal but there was no time to dwell.

Time to lay down the power

The race started with some usual bunch riding antics and an average speed of 31km/h. The initial 5km had some wide and narrow road sections through rolling farm land and some fast singletrack descents and climbs. I was riding in a good position and tried to do as little work as possible for the most gain, which had me floating around the top 6. While I tried to ride as smooth as possible, I still had a Normalised Power of 340w with three 800w+ power spikes in the first 10min.

From there it was all downhill … well for the next 8km at least. The descent had some small climbs that reduced the front bunch a few riders at a time. I was happy to sit back and enjoy the relative anonymity that comes from being an Australian in Germany for the majority of the descent and only moved up a few times when I sensed some singletrack was coming up. Not the hardest thing to sense though, when everyone drops it into the 11t and starts sprinting there’s probably a trail entrance coming up! There were a few interesting moments when people attacked on the flatter sections of road to try to force a gap but following wheels had me back up the front quickly with little energy spent.

The full segment.

Once we finished the descent, we meandered along the river bank for a few hundred metres and then made a right which put us onto the climb that would take us back up to the ridge line. This is where the final selection occurred 15km into the race after 30 minutes of riding. After making the right, it was a short wide section before a narrow walking bridge. To maintain position before the bridge, which after some sketchy cornering I was third, I put out a short sharp effort of 755w with a peak of 1031w. Not the best way to start a 6-minute climb but with such a narrow and steep trail it was important to hold a good position as moving up would become increasingly difficult.

A #Fullgas start

The leader at this point, and eventual winner, opened a gap and I was stuck behind second place, highlighting the need for good positioning. For this 1:51min section you can see my power gradual drop off as I sat behind second and my speed was dictated by his strategy.

State of affairs after the wooden bridge.

Sitting in 3rd.

By this stage, the leader was moving clear and I wanted some clear track to try to bridge across. But with such a narrow trail it was difficult and I needed to go into the rocks and grass to make the pass. A small power spike of 673w had me clear and then it was a 3-minute effort up to the leader at 384w or 5.91 watts per kilogram. The climb was still alternating between rough singletrack and smooth track but I tried to keep the power smooth over the rough terrain and do just enough to get me up to the leader but not go too deep. I caught his wheel at the end of this section and you can see my power drop off as I settled into his pace.

Bridging across to the leader.

Over the top, the racing was still on as the leader made one final attack to see who could follow. Another 11-second effort with a peak of 880W followed as I bridged to his wheel. While not as large as the other attacks earlier in the race, it was still another one in the legs that would catch up later. The race settled down from here though as our small three-man group worked along. I tried to make a gap a few times in the single trail sections and did successfully dropped the eventual winner, but once the road opened up he was able to close it down quickly.

Small attack across the top.

But what can you take from this scenario? Whether it be a road or MTB race, this pattern is pretty typical. The main points to look at are the fast start and the fluctuations in power. So, in training this is relatively easy to replicate. On a 6-10 minute climb, you can roll in and hit the base very hard for 10-30 seconds, followed by 2 min at hard and 2 min at really hard. Alternating between the two until the top. Or, if you have a power meter, hit the base at 145%+ of your FTP (mid to high anaerobic power) and alternate between 2min at 106% and 2min at 115% of your FTP (Vo2 power). This should get you accustomed to changes in pace that are common in race situations as well as being able to handle the intense start that may be needed.

Of course this is only one 8-minute climb in a 2-hour race and there is a whole lot more that goes into winning. While my race ended with some cramps towards the end, which could be due to a whole host of factors including the intense start, it was still a successful day and weekend out and gave me a lot of knowledge into how my body reacts to back-to-back racing. This knowledge should come in handy in regards to pacing and such with the Vaude Trans Schwarzwald only days away. Keep an eye out on MarathonMTB.com and social media for reports and inside details from the race!

If your a little lost, you can read up on some of the power terminology HERE and HERE.

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