VO2 Max & Other Lies

VO2 max is a measure of the maximum volume of oxygen that your body can use. As you increase your exercise effort, the amount of oxygen you consume increases to meet the greater demand to produce energy. However, there is a limit to each person’s oxygen consumption, and therefore a ceiling on your energy production and sustainable exercise effort. This measure which is computed in milliliters per kilogram of body weight per minute (ml/kg/min) is commonly used in running and to a lesser extent in cycling.

While some sports scientists argue that running performance is often first limited by other factors, such as muscle adaptation or running efficiency, others believe VO2 max is the key physiological determinant of an athlete’s running performance. Because of this many GPS enabled training watches (attempt to) track this metric. Below is a look into my Garmin’s Fenix 2’s sad attempt to determine my VO2 Max over the last year of training for an Ironman.

Year VO2 MaxMonth VO2 Max

The pic on the left shows the trend from April 2014 when I got the Fenix 2 through September 2014. The pic on the right shows the trend for the month of October 2014. (The rest of 2014’s screen grabs were lost in a tragic iCloud incident)

While Garmin’s literature claims it computes one’s VO2 max due to a fancy algorithm analyzing only your heart rate monitor data, the sharp cliff on the end of the year view pic proves otherwise. The first dip in my otherwise rapidly rising maximum was when I took a run outside instead of on my treadmill. Seeing the change, I followed up with several more outdoor runs which resulted in my meteoric fall from VO2 max greatness. Apparently my Garmin was guesstimating my treadmill speed at much faster (and slower) than was, in fact, occurring. I hadn’t noticed this fact as my supposed 4 min mile pace runs were being offset by my 0 mph walks in my interval training. This resulted in a believable average pace (when I occasionally looked at it). But since I was mainly using the Garmin for the heart rate data and my treadmill for speed data it took that long for me to notice the issue.

Since learning of this, I’ve purchased a footpod and calibrated it so that the Garmin Fenix 2 accurately captures my indoor speeds.  Sadly, even though my resting heart rate is on the verge of cracking into the 40s (stupid 50 bpm barrier), the Fenix 2 now reports my VO2 max as 43 placing me in the bottom 40% of men my age. Which is hopefully active men my age or its even more depressing.

As far as I can tell, the fancy algorithm is primarily looking at how fast you run for a sustained period to create this make believe number. This means 1) it requires a calibrated footpod to even have a chance of working indoors and 2) it really needs you to run at a constant pace – intervals really confuse it. So while this metric is worthwhile if properly measured (i.e. a sports facility treadmill test with a tube measuring your breathing), I’d take the “estimated” values with a large bag of salt. For a cheap and easy alternative metric grab something like this $20 pulse monitor and track your resting heart rate.

5K Ironman

That’s right, I’m training for an Ironman, but only running 5Ks!

OK, OK. It’s a Half Ironman (1.2 mi swim, 56 mi bike, 13.1 mi run), because people that do full Ironman events are crazy. And I’m only half crazy. ;)

An-exhausted-runner--001How is this possible?

Running hard. Really, really hard. While traditional endurance training is lots of miles at a moderate pace (ignoring “speed work”), I’ll be doing intense, interval style running.  I mean if I can sprint up hill for 3.2 miles that would have to translate into the ability to run (or jog) a lot farther, right? …right???

Why are you doing this?

I initially got into trisport because I needed a reason to workout and I enjoy both swimming and biking. I first set my sights on a Sprint Tri and then later an Olympic Tri. But I slowly fell out of it because training at long distances was too much of a time commitment. Then I went back to grad school and my free time all but vanished.

I got the idea from Tim Ferris’ book The 4 Hour Body that covers how intense interval training can substitute for moderately paced longer mileage training for marathons or even ultra marathons. His book includes a full training schedule with different intervals for different days (runners do seem to love complicated schedules – just pick up any running magazine), but I wanted something super simple, so I distilled Tim’s two chapters into this:

The Plan

  • Run 5K worth of intervals (run/walk/repeat) on my treadmill increasing the running speed, incline or ratio (more running or less walking) as I’m able.*
  • Run my 5Ks 3 times a week.
  • If it is nice outside or if I actually make it to the pool: substitute an hour or less of riding or swimming for one of my 5Ks.

Progress

When I started in December I was only doing 2 min of 10 min/mi pace runs with 2 min walks, because grad school had gotten me completely out of shape.  Now I’m doing things like running 7 min mile “sprints” for a half mile, or 12 min mile jogs up a 10% incline for 2 min intervals, or three 9 min 1 mile “distance” runs. Not great, but no longer embarrassing.

Disclaimers

I feel like I should point out the fact that I hate running. It sucks. Unfortunately it is both effective and efficient at preparing my heart and body to attempt the craziness that is the Ironman 70.3 in Galveston, Texas on April 26th.

The longest I’ve ever run is 10 miles. The longest I’ve ever swam continuously is ~55 min and ~1 mile. The longest I’ve ever biked is ~36 miles.

* I do not include my warm up (3 min walk then 1 min run walk intervals at 5, 6, & 7 mph) and cool down (3 min walk) in my 5K interval distance. I do include the distance walking between the running portions of the main intervals.

#5KIronman

Scott Share’s From His Heart

There were some requests to get some more info on my interval specifics. I use a treadmill because it is so much easier to set speed and time than running out in the real world constantly glancing at your GPS watch.

photo

This heart rate data includes my warm up (3 min walk then run 1 min at 5, 6, & 7 mph with 1 min walk between) and cool down (3 min walk) and 3 miles of actual interval running (3 min at 7 mph and 2 min walking both at 0.5% incline).

You’re Fatter Than You Think

…at least I am anyway. After years of living in the blissful land of inaccurate skin fold calipers, I found out that Texas A&M has student rate on DEXA scans ($55). So I decided to get a truly accurate picture of my % body fat and was shocked at the results.

First for those that aren’t aware, the DEXA scan uses extremely low levels of radiation to determine your fat, muscle, skeletal, and water weight. How low? It’s around 1/40th of a typical chest x-ray, and the fact that the doctor sits next to you during the scan without a lead lined smock is pretty comforting. DEXA scans are currently the most accurate way to measure your body composition – better than traditional submersion methods or the “bod pod” (the 2nd most accurate). On top of that, you get a bone density measurement as a bonus. It goes without saying that calipers and “body impedance” scales are vastly behind any of the these methods.

Going into the test I felt pretty good. I have some room in my 32″ waist size pants and my caliper measurements put me at just 9.4% fat. Sure, I’m not yet the at the golden goal of 5%, but hey that’s why I’m training for an Ironman event.

DEXAscanThe shocking DEXA results? 17.1% fat!!!

Thankfully, Dr Martin was able to put a little salve on my wounded pride: DEXA scans are revealing much higher numbers than previous methods. A scan of 17% would have fallen in the 12-15% range using the former gold-standard submersion method. In fact, a study out of Texas A&M that tracked elite college athletes found female swimmers had an astonishing average of 22.2% body fat using the DEXA scanner. This is not to say those athletes have a bad body composition, but rather that our measures of “good” and “bad” levels of body fat were calibrated on a method (submersion) that was significantly under-reporting fat. So until the “conventional wisdom” and rules of thumb catch up to these more accurate measuring tools, prepare yourself mentally before undergoing a DEXA scan.

Now as with all methods, repeated measures with the same instrument will give the most comparable results.  Which is why I plan no revisiting the DEXA machine once or twice to track my progress towards becoming an Ironman.  Although I’m revising that goal of 5% to something more realistic like 12%.

Training For An Ironman Without Running Over 3 Miles

This post has been updated here

That’s right, I’m going to attempt an Ironman event without running more than 3 miles in training!

OK, OK. It’s a Half Ironman (1.2 mi swim, 56 mi bike, 13.1 mi run), because people that do full Ironman events are crazy. And I’m only half crazy. ;) The event in question is the Ironman 70.3 in Galveston, Texas on April 26th.

An-exhausted-runner--001How is this possible?

Running hard. Really, really hard. While traditional endurance training is lots of miles at a moderate pace (ignoring “speed work”), I’ll be doing intense, interval style running.  I mean if I can sprint up hill for 3 miles that would have to translate into the ability to run (jog?) a lot farther, right? …right???

Why are you doing this?

I initially got into trisport because I needed a reason to workout and I enjoy both swimming and biking. First I set my sights on a sprint tri and later an Olympic tri. But after that I slowly fell out of training because it was too much of a time commitment. I enjoy bike riding but, I can’t often find half a day to drive somewhere nice and then bike 24-32 miles. When I went back to grad school, my free time all but vanished.

I got the idea from Tim Ferris’ book The 4 Hour Body that covers how intense interval training can substitute for moderately paced longer mileage training for marathons or even ultra marathons. His book includes a full training schedule with different intervals for different days (runners do seem to love complicated schedules – just pick up any running magazine), but I needed something uber simple.

I distilled Tim’s two chapters into this: run intervals on the treadmill (run/walk/repeat) increasing the running speed, incline or ratio (more running or less walking) as I can, and don’t run more than 3 miles.

So far I’ve increased from 2 min of 10 min/mi pace runs with 2 min walks when I started in December to 3 min of 8:30 min/mi pace on a 1% incline and 1 min walks. My distance has increased from less than a mile to about two miles (including warm up). With warm up and cool down this takes me less than 30 min to complete. I have been taking 1-2 days off between runs.  If it’s a nice weekend, I’ve taken a bike ride around my house for about 10 miles (~50 min) instead of running.  The pedaling on such rides has gotten noticeably easier as my running has progressed (It’s working! *maniacal laughter*).

Tune in soon for my write up on test #1: The Aggieland Sprint Triathlon.