Running using a power meter?

"So what’s ugly? Well, not actually the accuracy. Because as I said above – you can’t verify that. Nobody really can outdoors. Indoors, there’s some possibilities there, but even with that there’s disagreement in the scientific community on what the definition of running power should be."

dcrainmaker.com

Garmin Running Power App: The good, the bad, and the ugly

@dcrainmakerblog

Today, Garmin released their running power app that they announced back in October. The functionality requires a Garmin RD-POD, Garmin HRM-TRI, or HRM-RUN strap. It also requires the latest Garmin watches, specifically either...

Link:www.dcrainmaker.com/2017/12/garmin-run...

Supposedly, the Stryd is very accurate on pace, and it will register pace to your watch more precisely than GPS. So there's that.

I had a Stryd when I was running a lot and as someone mentioned a huge benefit of it is accuracy. I was running at lunchtime a lot and that put me on different treadmills at the gym, and it's great for getting a correct mileage there.

If you're into it you can use it like the cyclists do, training by zone, and establishing those zones using an FTP test. I was never dogmatic about them but I was conscious of keeping easy runs in zone 2 most of the time, by both pace and power. For a tempo (threshold) run it was the same. At the start of the run I stuck to a prescribed pace or power as it's really easy to start too fast. Later in the run it gets harder and there's less temptation for that. Anything faster than threshold I kept more of an eye on pace than power.

As noted, running power is going to have a lot of assumptions built in.

For biking, the definition and measurement of power is going to be easy: force on the pedal times the distance the pedal moves. That is going to be the energy transferred to the bike.

For running, it is force on the ground moving your body. Measuring both of those (remember direction is important also) is going to be almost impossible. As well as things like when your foot hits the ground the force and motion are going to be in opposite directions so power will be negative. How is that counted in output power? Some will be returned (more with supershoes) but not all.

It’s a junk marketing stunt with phenomenal marketing. There are exactly two measuring devices that are in any way, shape, or form, accurate:

1. digital stopwatch

2. properly work chest strap

GPS watches are “good enough”. Step rate monitors are easy to confuse at walking speeds but actually pretty decent and hard to confuse when running.

anything else that uses a black box algorithm like Stryd is junk.

Turtleb is spot on. Great tool for cyclists. Not applicable for runners. Absolutely correct on the point about negative power, and also the complication with shoe spring. Physics and/or mech eng for the win.

I'm not sure what a power meter tells you, that running pace, heart rate or ones general feeling of exertional effort, cannot.

A power meter can tell you how much it sucks running or cycling in heat n humidity. It confirms what you already feel.

Defining power for running is tricky:

outsideonline.com

Rethinking What Power Meters Mean for Runners

mmirhashem

A leading company redefines what it's actually measuring, and explains why that's what we really wanted all along

Link:www.outsideonline.com/health/training-...

Its not negative power in Stryd its called Form Power IE power that isn't moving you directly forward - such as rotational movement, for most runners its about 25-29% of total power

Stryd and other power meters use 3 axis Accelerometers to measure acceleration and direction, Power is derived from that - and as such is not the same as power measured directly by a force plate, although there is good correlation between the measurements made with Stryd and measurements made with a force plate. That said it doesn't really tell you anything you didn't already know

Regarding negative power -- during the time in which your foot is exerting force on the ground but your center of gravity has downward movement (roughly the first half of stance phase) any physicist or mechanical engineer will tell you that the ground is doing work on you and your shoes, so from your point of reference you are absorbing energy or doing negative work. Of course your muscles are actually doing metabolic work, but how much? That would depend on how bouncy your tissues are, and also how bouncy your shoes are. No relation to what you say Stryd calls form power.

Good point but Your muscles are eccentrically contracting as it modulates the downward force otherwise you would collapse in a formless puddle at each step - some of that energy is elastically stored in tendons and ligaments and recycled at push off. Although I don't have any particular insight into the Stryd Algorithms but it would seem trivial to discard -take into account the "free" down force acceleration supplied by gravity since according to published papers styd power has good correlation to force place measurements

how do I delete someone else's post

The idea of the Stryd pod is to find a power value equivalent to your VO2 consumption. This seems to work if the running surface is flat (below something like 5% steepness).

If there is a higher steepness up/down (e.g. trail) the Stryd pod does not work properly.

The Stryd pod has a design problem. It has only one hole to measure altitude and wind. This is a problem, because strong wind bursts are influencing the altitude measurement and are leading to a wrong power meter result. A severe bug, not solved so far.

The biggest pro is that it shows the actual speed much more accurate as a GPS watch. Also you do not rely on a good connection to the satellite, e.g. in the forest.

Pointless metric. All it tells you is how much money you’re willing to waste on training gadgets you believe will magically grant you a marginal gain.