Ground contact time, stride length, vertical oscillation, and stride rate amongst various shoes

I wanted see how various minimalist shoes affect my ground contact time, stride length, vertical oscillation and stride rate.

To do this I used my Garmin 920XT paired with the newest Garmin HRM. You can see the raw data here.

Continue reading “Ground contact time, stride length, vertical oscillation, and stride rate amongst various shoes”

Garmin 920XT vs 620 vs 220

Garmin 920XT is a huge improvement over the Garmin 620

A few key features:

  • Daily activity tracking
  • Sleep tracking (with built in accelerometer)
  • Smart watch features (see emails, text and other notifications)
  • Indoor run tracking through accelerometer
  • VO2 max estimates
  • Race predictor based on last runs HR and pace
  • Large easy to read screen
  • Vertical Oscillation tracking (with HR monitor)
  • Ground contact time tracking (with HRM)

Garmin Forerunner 620 Review: Is it worth $450

The Garmin 620 has some pretty impressive features, but it cost $450, that’s $200 more than it’s little brother, the Garmin 220. Is it really worth the extra $200? Check out the above video for some of the useful features.

Here are a few of the notable features that differentiate the Garmin 620 from the Garmin 220
  • VO2 Max estimator
    • This is a really cool feature that estimates your VO2 max. It can even estimate this when running at sub VO2 max speeds. You don’t actually have to run all out. If you know your max HR, the watch uses math to estimate based on your speed and %HR
  • Race predictor
    • It can predict your current race fitness without making you run a time trial!
      • It takes your HR and speed of any given run and uses fancy mathematics to give you a prediction of your current race fitness, amazing! 
      • My race predictions were fairly accurate
  • Recovery Adviser
    • Based on things like heart rate variability, it gives you an estimate of how long it will take you to recover from any given workout. I ran a 10k time trial yesterday and it told me it would take 72 hrs to recover. I then went for a run today and it gave me an update on how well I was doing on my recovery; it told me I still need about 40 hrs to recovery from the effort
  • Run Dynamics
    • Uses and accelerometer in the HR monitor to tell you info about vertical oscillation, ground contact time, and gives you a real time score during your run to help you adjust your stride
  • WiFi: the watch has built in WiFi, so it can upload as soon as you step inside
  • Internal watch accelerometer: keeps track of your distance while on the treadmill. The watch will become more accurate after it calibrates automatically from the GPS data of an outdoor run (220 has this as well)
garmin 620 vs 220
garmin 620 vs 220
There are a lot of similarities between 220 and 620
garmin 620 cradle
620 uses magnets to hold watch in cradle
gamin 200 vs 620
620 is only slightly thicker and a little heavier
new garmin hr monitor
I found the new Garmin HR monitor to not have erratic HR data as the old ones did, it now has 3 sensors on the the strap plus a built in accelerometer to measure run dynamics such as vertical oscillation, and ground contact time
Both cradles can charge and upload data. The 620 uses magnets to hold watch in cradle, 220 use a snapping lock-down

ithlete Finger Sensor Heart Rate Variability Review

I’ve been using the ithlete heart rate variability app to monitor my HRV. The theory behind it is that the higher your HRV, the more rested and recovered you are. This can help you monitor when you should do a hard training session and when to back off. So far I’ve found it to be somewhat useful and have actually made adjustments to my training based off the feedback from the app. The app gives you 3 key colors to monitor your training:

  • Green: you’re recovered, ideal conditions to do a difficult workout
  • Amber: take an easy day or do something moderate
  • Red: take a day off or easy

I’ve found the ithlete finger sensor to give more consistent results when taking my HRV as compared to a bluetooth heart rate monitor. I also find it easier than having to put on a HRM and moisten the contacts.

ithlete finger sensor

ithlete finger sensor

4iiii Viiiiva Dual Heart Rate Monitor w/ iPhone Connectivity Review

The Viiiiva 4iiii HR monitor is a really cool concept. It connects via Bluetooth with your iPhone to send HR data from the strap itself, but also collects data via ant+ and sends data to iPhone from your Garmin footpod, cadence sensor, or Garmin power meter as well. I was hoping that for $80 it would overcome the limitations of the Garmin HR monitors, where they don’t work great until you start sweating, but alas, it has those same limitations. I mainly used this with my heart rate variability app called ithlete and occasionally with my Garmin 310xt when running. I have since started using the ithlete app with the ithlete finger sensor; it gives better, more consistent results.


Motorola S10-HD Bluetooth Headphones Review

I’ve been looking to try a pair of Bluetooth Headphones for a while now. This would allow me to listen to music, books and podcasts through my phone while getting rid of the annoying cord. I enjoy carrying my phone with me on runs to take pictures, listen to books, and music.
Unfortunately, the Motorola S10-HD Bluetooth Headphones do not deliver. While they are sweatproof and I can hear everything crystal clear, they are extremely uncomfortable! After just five minutes, they began to feel like the were digging into the side of my head.
I’ve been looking at the new Yurbuds Bluetooth Wireless Headphones and hope to give those a try sometime in the near future.
What has been your experience wearing headphones on the run? Do you wish you could cut the cord? Or have you found something that works? Let me know in the comments section below.

Garmin Foot Pod Review & Accuracy Test

One of the benefits to using a Garmin GPS watch to track your runs, is that it records all of your run data, which can then be uploaded to Garmin Connect, Strava, or other websites for further analysis. As the weather has gotten colder and the roads icy here in Minnesota, I’ve been doing most of my runs on the treadmill. By using the Garmin Foot Pod, you can keep track of all your indoor runs on the treadmill.

Attach Garmin Foot Pod to Vibram FiveFingers w/ Velcro
Place Velcro on the back of Foot Pod to use w/ VFF
Click image to buy velcro on Amazon

You could manually enter all of your data, but this can be tedious, and doesn’t track things like laps and changes in pace. This is where the Garmin Foot Pod comes in. The Foot Pod is a device with a built-in accelerometer that measures cadence and acceleration to estimate stride length and thus pace & distance. 

A more accurate speedometer

In addition to being used to estimate the pace and distance while running on a treadmill or indoor track, the Foot Pod can also be used while running outdoors to keep track of stride rate and pace. But why would you use a Foot Pod to track pace, when GPS already does that? 

GPS is notorious for giving runners erratic readings for instant paces. If you are like me and want to know how fast you are running, RIGHT NOW, then the Foot Pod can help. You can set the Foot Pod to show up on your Garmin GPS watch to give you the instant pace reading, rather than relying on GPS. The distance and average pace will still be tracked by GPS, but your instant pace will be estimated from your Foot Pod. Some runners find the Foot Pod to be more accurate and consistent.


I am obsessed with trying to find out exactly how far and fast I ran. I like to know how fast I am running to see if I am making progress. Can a little Foot Pod really be accurate? 

To get the most accurate calibration, go to a track and calibrate your Foot Pod. You could also use the built in GPS on your watch to calibrate the distance, though this will not be as accurate. Alternatively, you can calibrate using the Garmin Foot Pod Calibration Tool, which allows you to use longer distances to calibrate more accurately.

Accuracy Test

I tested the Foot Pod accuracy on a 2 mile run. I used a measure wheel to verify the distance. I initially calibrated the Foot Pod using the measure wheel, while running at about a 10 minute pace (which is the pace my dog likes to run). My dog and I then went for a 2 mile run with my Garmin 205, Garmin 310XT (GPS off and Foot Pod enabled), my iPhone 5 with the Garmin Fitness App, and the measure wheel. The run has about 75 ft of elevation gain and involved several stops with my dog.

measure wheel
Measure Wheel to Verify Accuracy


  • Measure Wheel: 2 miles (3218 meters)
  • Garmin 310XT w/ Foot Pod: 1.98 miles
  • Garmin 205 w/ GPS enabled: 1.99 miles
  • iPhone w/ Garmin Fit App: 2.10 miles

As you can see, the Foot Pod was extremely accurate. Measuring 1.98 miles gives a percentage error of 1%. The Garmin 205 using GPS give a percentage error of 0.5%, and the iPhone with the Garmin Fitness App gives a percentage error 5%.


I have found the Foot Pod to be extremely accurate when I am running a the pace I calibrated it to. If I calibrate the foot pod while running a 10 min mile, it does a great job of estimating my distance at that pace. If I deviate from the calibrated pace, the pace and distance begin to deviate as well.

Since I like to capture as much data as possible from my faster workouts on the treadmill, I calibrate the foot pod while running at a faster pace.

Treadmill Considerations

Treadmills are said to be notorious for inaccuracy. The foot pod will not give you 100% accurate information, but it will come close. 

I wear the foot pod for treadmill workouts because it is fun to see my pace, stride rate, and run dynamics. 
Garmin Foot Pod Cadence Chart
Garmin gives various colored lines based on stride dynamics

garmin run dynamics
Garmin gives you averages, max, and stride length
If I am doing a specific workout, and want to know the exact distance covered, I use the treadmill readout for measurement. I measured the treadmills I use with a measure wheel to verify accuracy. Both treadmills I use were within a couple of feet of true distance.

Bottom Line

If you use a Garmin GPS watch and would like to easily keep track of all your indoor running, or stride dynamics for outdoor running, I’d highly recommend the Garmin Foot Pod. While it’s not 100% accurate, neither is GPS and it makes looking at your data a lot more fun.