Which VDOT to use?
I know this has been asked by others, but couldn't find the answer when I've searched so sorry for asking again:
Last week I did a 10k race for testing purposes and finally got around to computing my VDOT from the results. My last 2 running tests in the JOS were the same 5k loops. Anyway, I was fairly happy with my results, but looks like my VDOT is lower from the 10k race results (race was actually 5.77 miles according to my garmin, so I am using that number to compute). Do I continue to use the higher VDOT used in JOS or lower it to the 10k results? I never had problems hitting my target training levels when using the higher VDOT, so I figure that this the one to use. Leads me to the next question - I used a 7 min/mile as a goal when running that 10k because it seemed the correct goal based on my VDOT (7 min is my Z4). I ran the 10k at 6:59 pace. Why would my VDOT decrease based on this?
Last week I did a 10k race for testing purposes and finally got around to computing my VDOT from the results. My last 2 running tests in the JOS were the same 5k loops. Anyway, I was fairly happy with my results, but looks like my VDOT is lower from the 10k race results (race was actually 5.77 miles according to my garmin, so I am using that number to compute). Do I continue to use the higher VDOT used in JOS or lower it to the 10k results? I never had problems hitting my target training levels when using the higher VDOT, so I figure that this the one to use. Leads me to the next question - I used a 7 min/mile as a goal when running that 10k because it seemed the correct goal based on my VDOT (7 min is my Z4). I ran the 10k at 6:59 pace. Why would my VDOT decrease based on this?
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Many people, including myself, use the 5K derived VDOT as the basis for training, even if a longer distance race (10k, half marathon) results in a lower VDOT. For IM racing, though, it is also common to pace the marathon from a VDOT about 2-3 points lower.
I think the TP, or Z4 pace, is actually supposed to be the pace you are able to hold for an hour. Since you're only running about 42 minutes in a 10 K, you need to go at a faster pace than your TP.
Look @ the calculator on >this< page, and plug in 43:30 for a 10K. Notice that under race pace, it says 7:00 min/miles; then under the training tab, for threshold the pace is 7:11
While this does not answer the question of which vDot you should use....
...the GPS is correct...the course measurement is correct....you ran the extra distance....the GPS follows you....not the course true measurement...so the pace your Garmin gave you is the pace you ran....remember on a course there is only one line between the start point and the finish point that measures the distance of the race....it is the plumb line so to speak...every step you take off that line is Added distance (as there is no way to run less than the plumb measure accurate distance)...that is why people always see 5.3 on their garmins for 5ks or whatever...but your time as measure by your watch is the time it took you took cover the distance you traveled NOT the course distance ..UNLESS you ran exactly down the plumb line...which is highly unlikely.
You only have to display instantaneous pace to see that — even when stationary, the pace will vary all over the place.
The reason being that the GPS receiver is triangulating all the satellites it can see to derive a location — what it usually does is it derives a circle that the receiver is in.
And the changing of the instantaneous pace reflects the receiver's changing estimate of the location, notwithstanding that the GPS receiver isn't moving in this example.
So, when you are running, the same thing is occurring. Thus, GPS receivers are not completely accurate.
Just saying.
Finally, someone else who understands the 'fuzzy' location capacity of GPS.
The way I describe it to our foresters is at any given time you are somewhere within a circle with a radius of between 20' and 50'. You are never in the center of that circle. The diameter of the circle changes over time (grows and shrinks) AND the circle itself wobbles on the ground over time.
Can anyone explain that?
Somehow most people have that, every half mary I ran had 13.2 miles for some reason. It also makes me wonder how the course is measured in the first place. Using GPS from a car? What about all those races where not every part is accessible by vehicle (like running over a foodbridge, a pier, etc)
I've seen Race Directors who use a bicycle wheel to measure his courses. It is a single wheel on a stick he rolls out in front of him. The wheel has a little cadence magnet on it which transmits to a head unit he carries. Those things can calibrate to the millimeter.
Googling, I found this:
http://ceramics.org/ceramictechtoday/2012/07/06/olympic-marathon-course-comes-down-to-nist-calibration/
Which links to this:
http://www.usatf.org/About/Committees/Long-Distance-Running/Road-Running-Technical-Council/Historical-Information/Jones-Counter.aspx
I understand the fuzziness of GPS...but on a certified measured course there is only one line between the start and finsh which defines the exact race distance...hence it garuntees ONLY that everyone that crosses the start line and the finish line...following the designated route..runs a MINIMUM of the course distance....every step variance from the line is EXTRA distance...so my point is that the odds that the GPS distance is more correct...is greater than you thinking you ran on the plumb line...thats all...on a short straight course no big deal...on a longer run or with many turns....that added distance adds up.
ps...the emphasis is not shouting..just engaging in friendly chat here
& BTW...Love the graphics!
Okay...back to the original question; If I were choosing a vDot for training purposes....I would go with the faster and see how the workouts felt...If I could hit the numbers without trashing myself...then I'm good....If I really couldn't hit the workouts or could barely make them...I might back off...but I would start with the faster number...
Caveat...would this represent a really big jump from your current number? ...if the faster pace really didn't make much sense...ie. How did I run that fast? then either a.) go with the slower pace vdot...or b.) swag in between.
Why would your vDot decrease based on running a 10k at your target Z4 pace....possible explanation.......I'm assuming your vDot was around 48/49....if you look at predicted race times for longer distances based off that vDot...the 10k time is not @ 7min/mile even though your Tempo/Z4 pace is pegged at 7min/mi...in the case of a 49 vdot T/Z4 pace is 6:58 but the predicted pace for a 10K race is 6:48......therefore if your ran at 7min pace you ran below the expected performance for your vDot and it would adjust to reflect that....You can see the predicted race performances based off of Daniels vDot here...
http://www.attackpoint.org/training...me=42%3A03
Note: USATF does not specify 10ft. from the curb...the course measurement requirement is stated as:
Measure the course......following the shortest possible route as it will be available to the runners on race day.
and as an example ...these excerpts from USATF describing the course measuring procedure".....You make a sharp right-hand turn onto xxx Road, staying close to the right-hand curb as you round the corner. Since the next turn will be a left, you sight a straight diagonal that will take you to the curb at the northeast corner of the intersection ....Your next turn is left onto a winding bike path. You carefully follow the shortest route, crossing from one side of the path to the other as needed to follow the shortest route."
I'm not trying to be difficult...my only point is that on certified courses...the greatest variabiliyt is most likely to be the route you actually ran...not the course measurement or GPS
Heres another link...describing the impact of running or not runing the tangents (plumb line) of the course....
http://howtorunamarathon.net/Run_the_Tangents.html
...and lastly ...I love this video of the the 1983 NYC Marathon....Rod Dixon catches and passes Geoff Smith with 200 yards to go...by properly running the tangent while Geoff ran in the center of the road....Rod notes this in his commentary...its how he caught him...not by running any faster over the final 10k..
http://www.youtube.com/watch?v=llfc...LwIZ8hFnlw
Since your talking about testing for training paces, use the Garmin distance and race time. Regardless of the actual distance on the course, your Garmin is what you will be training with on a daily basis - with the inherent flaws in distance reporting every time you go for a run - apple to apples.
If you feel the vDot is off, retest on the 5K loop you've used before in JOS and earn the right to go faster.