Runners wanting to improve how they train and do better on race day should seriously consider Garmin’s Running Dynamics Pod. That’s because once paired to compatible fitness watches such as the new Fenix 5 or Forerunner 935, it measures 6 important running metrics – giving you the tools to up your game without having to wear a chest strap.

Becoming a better runner so you can up your rankings and hopefully start collecting some medals isn’t easy. Commitment to regular training aside, it requires that you monitor key aspects of your running and fitness progress on a continual, ongoing basis. You also need to know what your performance level is right now. Otherwise, how will you ever expect to improve or, for that matter, realise you’re hurting yourself by over-training?

That said, Garmin’s Running Dynamic Pod provides all the data you need to understand your current form and become a better runner – if you take its advice, that is. Measuring six running metrics; cadence, ground contact time, ground contact time balance, stride length, vertical oscillation, and vertical ratio. It clips conveniently onto the back of your pants in the small of your back, allowing you to kiss uncomfortable chest straps goodbye forever. And, powered by a CR1632 coin cell battery, it can run (excuse the pun) for a year before you need to replace it.

Oh, and it’s tiny. Weighing just 12 grammes – that’s less than 9 standard office paper clips – it’s so inconspicuous you can literally forget it’s there. So much so, it might end up in the wash along with your pants, if you’re not careful. To prevent this from happening, Garmin has included the prompt “Remember to remove your RD Pod” that appears on their fitness devices the moment you shut everything down.

DC Rainmaker’s advice is the best I’ve come across yet. He suggests the moment you switch everything off, you immediately attach the minuscule, bright green pod to one of your running shoes. That way, he surmises, it won’t get subjected to a high spin cycle by mistake, plus you’ll know exactly where to find it when you need it again. The way I see it, that’s good, solid logic.

What the Pod does in a nutshell
Basically, what the Running Dynamics Pod does is deliver the same running dynamics data traditionally provided by HRM-RUN and HRM-TRI chest straps, but without the strap. Your fitness watch’s on-board optical HR sensor now monitors your ticker and takes care of the rest. Featuring a built-in accelerometer that measures precise torso movements, the pod calculates these six running metrics, which provide the following info:

  • Cadence is the number of steps per minute. It displays the total steps (right and left combined).
  • Ground contact time balance calculates the left/right balance of your ground contact time while running as a percentage. For example, 53.2 with an arrow pointing left or right.
  • Stride length is the length of your stride from one footfall to the next, measured in meters.
  • Vertical oscillation is your bounce while running. It displays the vertical motion of your torso, measured in centimetres for each step.
  • Vertical ratio is the ratio of vertical oscillation to stride length displayed as a percentage. A lower number typically indicates better running form.
  • Ground contact time is the amount of time in each step that you spend on the ground while running measured in milliseconds.

Specifications
Dimensions (pod in clip): 37.6 mm x 23.2 mm x 19.2 mm
Weight: 12g
Battery life: 1 year (assuming 1 hour per day of use)
Battery type: CR1632 (user-replaceable)
Connectivity: ANT+
Water rating: 10 metres
Compatible devices: All Fenix 5 models, Fenix Chronos, the Forerunners 735 XT and 935, Quatix 5 and Quatix 5 Sapphire

Running metrics in more detail
Having all this amazing data at your fingertips is one thing, but understanding what it all means is another. That said, here’s a more detailed breakdown of the running metrics that the Garmin Running Dynamic Pod provides:

Ground Contact Time
This is the amount of time which each step spends on the ground while running. Ground contact time is typically fast, so it’s measured in milliseconds (ms). It tends to be especially short for elite runners, who often have ground contact times of 200 ms or less. Virtually all experienced runners have ground contact times under 300 ms, probably because they’ve learnt to “pick up” their feet quickly and not over-stride while landing. Over-striding is where the foot lands too far in front of the body, leading to braking forces at impact and, typically, longer ground contact times.

Ground Contact Time Balance
By monitoring the balance between your left and right feet as they hit the ground, this metric calculates your symmetry as you run. It’s always displayed as a percentage greater than 50 percent, with an arrow pointing to the left or right to indicate which foot is on the ground longer. For most runners, a more symmetrical running form is preferable. Colour gauges featured on Garmin watches and Garmin Connect shows how your balance compares to other runners. Many runners report that GCTB tends to deviate farther from 50/50 when they run up or down hills, when doing speed work or when they’re fatigued. Anecdotally, some runners also notice that injuries are reflected with greater imbalance.

Cadence
Simply put, this is how many steps you take per minute, counting both feet. It’s a commonly measured running metric that tells you a lot about your form. For example, at a given pace, a quicker cadence and shorter stride length translate into smaller forces being subjected to many parts of the body, such as at the ankles, knees and hips. The reduced impact of these forces is also widely believed by experts to reduce injury risk. It’s clear that running cadence can be increased only so far. However, for more injury-prone runners, working on increasing their cadence could be beneficial. An often-cited target for running cadence is 180 steps per minute, but taller runners tend to take somewhat less. Interestingly, higher cadence is also associated with lower vertical oscillation and shorter ground contact time.

Stride Length
Another key part of measuring your running form – stride length – is how far you travel with each left and right step. It’s shown at the end of your run, or as an inactivity data field, you can view while running. Later, you can view this data in more detail on Garmin Connect to check how your stride length varies with your pace, cadence, elevation or other metrics. It’s dependent on a number of factors, including body morphology, muscular strength and flexibility.

Vertical Oscillation
This reflects the amount of “bounce” in each step while you run. Measured at the torso, it tells you (in centimetres) how much you’re travelling up and down with each step. Many running coaches believe that lower vertical oscillation is more economical because less energy is wasted going up and down. In general, more experienced runners tend to have lower vertical oscillations. However, faster paces often come at a cost of higher vertical oscillation. Vertical ratio (see below) takes this into account. Another advantage of lower vertical oscillation is it typically means less stress on the lower body during impact.

Vertical Ratio
This reflects your running efficiency based on how well you propel yourself forward with each stride. Vertical ratio is the amount of “bounce” in your stride, divided by your stride length, then expressed as a percentage. Since stride length is the horizontal movement of running, it’s the benefit of the action, whereas vertical oscillation is one of the energy costs of running. A low vertical ratio number indicates a small cost for a large benefit – which means more efficient running. – (c) 2017 NavWorld

About The Author

Sean Woods

Originally a photographer for the Star newspaper in the bad old days, Sean Woods turned to writing after the first democratic elections in '94. The career shift paid serious dividends, culminating in him becoming associate editor for Popular Mechanics magazine with a number of technology writing awards under his belt. His interests include anything to do with boats, motorcycles and all those fancy tech gadgets that help the modern world go around.

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