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HRM straps and breast movement (lemmy.blahaj.zone)

submitted 3 weeks ago by [email protected] to c/[email protected]

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I'm seeing weird results with my heart rate strap. My ground contact time is really low, but my vertical oscillation is really high! One indicates good form, the other indicates bad form. My subjective experience is that my vertical oscillation is low, but my garmin disagrees.

And I think the reason why is the movement of my breasts. I think they're moving the sensor itself, and confusing its measurements.

Is that actually a thing? I've tried to find research or people talking about it, but all I can find is discussion on the impact of breasts on actual running performance, rather than on the measurement of it.

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[–] [email protected] 0 points 3 weeks ago (1 children)

They are just using electrical contact with the skin. In this X-Ray the electrical connections are made at the little tab at the top and bottom of the circuit.

This is not a MEMS based sensor or anything mechanical that can be changed by impacts. My understanding is that the electrical may have some drop out from signal pairing not being well matched.

In the early days of Garmin cycling computers. Bike mounted units that came packaged with a heart rate strap worked flawlessly. However, adding a new strap to pair with an old unit only worked around 2/3rds of the time and often resulted in returns comparatively speaking. It was one of the things I dealt with in the bike shops.

https://en.wikipedia.org/wiki/Heart_rate_monitor

[–] [email protected] 0 points 3 weeks ago

It's not my heart rate measurement that has the issue. The device has an accelerometer in it to that measures running movement metrics, so it can determine things like stride length, vertical movement with each stride, ground contact time, and the ratio of time spent on each foot. What I think is happening is that because of the positioning of the strap, just below the breast crease, incidental breast movement is moving the strap and sensor enough to impact the accelerometers measurements.