My last months in Nepal I ran a lot with my friend Thomas, a former close-to-elite-level 800 meter runner. We talked a lot, which for me is very much part of my running enjoyment, and one of the lessons learned was that all running isn’t the same. For Thomas, what we did wasn’t running. What exactly the appropriate label should be is something else, but he did convince me that running at high speeds is really different from running at slower speeds.
A contribution of Zach Bitter to irunfar about his recent 100 mile American and record and 12 hour track World standards, (respectively: 11:47’13” and 101.66 miles) brought this back to mind:
Just as people can generate a lifestyle around training in the mountains, speed can do the same. There is something about the hours following a really hard speed session of intervals, progression runs, fartlek workouts, or the like that leaves a person feeling powerful—even accomplished. It can be hard to find the motivation at times, but there is just something about speedwork that breathes life into your lungs. A sense of accomplishment when you hit your split or reach a new mark on a particular training route.
Obviously there is a very broad overlap between speed and endurance. The marathon elite runs at speeds that are inconceivable to a slug like me, and simultaneously require enormous endurance. But at every level (which is ultimately a genetic given), there is considerable overlap between speed and endurance. Physiologically, the two basic constraints on the possible mixes of speed and endurance are the main source of energy and running style.
Let’s start with fuel: in simplified terms, anything beyond full sprint uses a mix of fast-access carbohydrate and slow-access fat burning. There is plenty info out there and I am not going to elaborate further, but the core of it for my argument is that the endurance system – which is slow access energy based – needs a bit of fast access supply of carbohydrates – of which we can store only a limited amount. So if we’ve used it up, that store needs replenishing by eating to function. The harder one’s leg muscles work, the less one can resupply because that requires the body to shift resources (especially blood) to the stomach. So, starting off with a full fast-access storage, whatever the distance the optimal way to use the fast-access store is to ensure one runs out at or not far from the finish. Training will move the parameters of one’s personal equation, but within limits. Just looking at current world records one can see that this translates in slower and slower average speeds with increased distance:
- 1500 meters: approx 23.75 km/hr
- marathon: approx 20.5 km/hr
- 100 km: approx 16.05 km/hr
- 24 hours: approx 12.65 KM/hr
About running styles from the perspective of speed versus endurance there is much less out there and I want to share with you the analysis that made most sense to me. It comes from the ironman community. The female elite will run its marathon slower that 15 km/hr, a speed still achievable by any running style but faster that this requires what is called the gazelle style in this interesting video:
The gazelle style allows runners to reach the faster speeds but it is also putting more stress on the body because it requires the more up and down motion so as to increase time in the air. That implies landing with more force.
Looking at running from this energy system/running style perspective, gives you three “categories” of running. The first and last are qualitatively and experientially different activities:
- fat-burning at refuelling level gliders’ endurance style
- overlapping category
- optimal fat-burning gazelle max speed style
Both endurance and speed athletes become injured, but given appropriate amounts of training, the first category is way less injury-prone. Once athletes start pushing the envelope moving into the overlapping category, they start entering the danger zone. Stress on bones and ligaments and/or on metabolic and other physiological systems starts moving direction breaking point. My perception is that the third, speed-maximizing category is the most injury-prone. But being a slug I’m obviously biased and looking for confirmation that my preferred style is healthiest. Nevertheless, no one would argue these days that evolution build us more for endurance than for speed.
For those who are like me and enjoy ingesting confirming “evidence”, this documentary does that ever so nicely: