Inquiring Minds > Re: Run Training
While I don't start the OutSeason until January, I had a thought (or question) that I wanted to throw to the team and coaches for feedback.
Why do we structure workouts with bike intervals by time but run intervals by distance?
For the purpose of this post, and to simplify things, lets assume we have perfect test data, and that know our FTP on the bike and threshold pace on the run (or threshold power on the run should you be so lucky).
Lets take a classic OS wko, 2 x 15' at FTP. In 2018, your FTP may be 250w. You do your 2 x 15' at 250w and it nets you a TSS of 75 for the wko. The following year in the OS, your FTP is now 270w. You do the same 2 x 15' as you did in 2018 and it again nets you the same TSS of 75 because its a sliding scale and the effort your 2018 and 2019 selves put forth was the same. The 2019 you is just stronger and pushed more watts on the dial, but it was effectively still at 2 x 15' at 100% of your FTP.
Now lets look at running. Your 2018 threshold pace is 8 minute miles. You go out and do a 3 x 1 mile at z4. You traveled 3miles at threshold and it took you 24 minutes. 24 ' at 100% , or threshold. A year later you are more fit and thus faster. Your 2019 threshold pace is 7 minute miles (go you!). You go out and do a 3 x 1 mile at z4. You traveled 3 miles at threshold and it took you 21 minutes. 21' at 100%. ...wait a minute...
So on the bike, since we use a time domain, the stress we put on our bodies is the same year over year regardless of our fitness. Doing 2 x 15' at FTP hurts the same for everybody whether your FTP is 150w or 400w. On the run however, we use a distance domain to measure intervals. So why is the slower paced individual doing 24' of threshold work while the faster individual is doing 21'? We could suppose both athletes are running a total of 1 hour. Then that 3' difference between athletes, while not completely made up, is seen in the z2 cool down of the faster athlete. Its just curious. If you have seen gains in speed and fitness at 24' of threshold, why would we then start to lower that number to 21' (~15% less work), or more if you have picked up more than a minute on your threshold pace. Taking that mentality to the bike. in 2018 you may have done 20' intervals, then in 2019 you are doing 17' intervals (15% less) and calling it the same workload.
I am thinking I may take a stab at the OS using timed intervals over distance. Why not? Now to figure out my basis for the conversion rate. 1 mile = 8 minutes? Anyone have any thoughts?
Comments
I'm sure I'm unusual, but I have almost always used time over distance for running, so long runs are measured in time, not distance and the same with intervals. I don't think of running mile repeats, I think of 8 minute intervals or something like that. For long runs I find that runs over 2:15 just take a lot out of me and I need a longer recovery time so I use that as an approximate cap.
Whenever I'm working out I always have a "need to stop by time" in mind, so time measurement is just easier for personal and family time management.
I think that at the end of the day it's all about consistency and stressing your body appropriately.
Tom
That's a great question. I'm a numbers guy and typically run by miles. Even when the EN training plans are/were in minutes, I would convert it to miles. Using miles allows me to easily see and measure improvement. With that said, there are situations when it's better to use time, such as for long runs in hot and high humidity conditions, on very hilly terrain or trail running.
I'm not a TSS expert, but you might be comparing apples and oranges with bike intervals and run intervals. rTSS is based in pace, ngp, and IF and duration. Therefore, for example, slower paced 1K intervals will give a lower TSS than faster paced 1K intervals. That's my guess as I don't think you can pre-determine rTSS like you can bike TSS. Even run power is based on pace, grade and whatever else. Perhaps the difference in shorter run times over the same distance as fitness improves is made up in higher TSS?
@Derrek Sanks I guess I do the inverse. Since I'm in hot, humid weather I run by time. I measure improvement comparing miles over the same time period.
Also like @Tom Glynn stated time allows me to give my spouse an expected time to be back home.
I have always been curious about time on feet element. Faster runners will finish distance based workouts faster, but I guess stress level on the body would need to be made apples to apples hence TSS. I admit I never use TSS for anything and use more IF.
Appreciate the responses.
I concur that long runs are a different animal where distance is appropriate to a certain point, but then for slower average paces - time comes into play.
For this post I was really inquiring about thoughts regarding cumulative threshold and above efforts. I am not really looking at total run time or distance, just the specific intervals and time in the assigned zone. With bike workouts we can measure, in the OS for example, week over week the increase in time at threshold watts. However for threshold runs, we measure miles, and as you get faster you are actually spending less time at threshold in your run workouts where as your bike threshold time is constant year over year regardless of your level of fitness.