Validity and reliability of portable gym devices and an iPhone app to measure vertical jump performance

Version 2 (15th February, 2019)

Annex1: Anatomical placement of the PUSH system

5 comments

  1. First, thank you for your hard work on this study! It’s great to see independent validations of our tools! I am the resident sport scientist at PUSH and I have a few questions/clarifications for you to consider:

    1) Is this on PUSH band 1.0 or 2.0? Not stated anywhere? What about software/firmware version? Given the current state of signal processing and limitations being software based not hardware based with the rapid innovation of technology, this information is important for the reader to understand.

    2) The methods state the band is worn on the middle of the back as suggested by PUSH. Our app has a video showing the band worn on the pelvis, as that is where it is designed to be worn. Images of placement would help users to understand. This could explain differences seen in jump height similar to the discussion around GA. Regardless still great to see how well the other metrics hold up when the PUSH band is worn on the torso!

    3) In fig 4. it is incorrectly stated our app is subscription pay only. Our app is, and always has been free. Anyone can go to apple store right now and download app for free. There is a web-based desktop software (PUSH Portal) that allows users to program training and export data among other things. This is subscription based. Please clarify which you are speaking of?

    Thanks again! Look forward to hearing from you.

    • Hi Chris,

      Firstly, thanks very much for reading the paper and providing your insightful queries. The comments would help provide a more detailed reporting of the study and we appreciate your input. Please find the response to your queries below.

      1) Is this on PUSH band 1.0 or 2.0? Not stated anywhere? What about software/firmware version? Given the current state of signal processing and limitations being software based not hardware based with the rapid innovation of technology, this information is important for the reader to understand.

      We used the PUSH band 1.0 which were purchased as part of operations in our performance setting. These PUSH devices were purchased prior to the release of 2.0. We will include the Firmware (1.3.1), App Version (4.2.0) and the PUSH model.

      2) The methods state the band is worn on the middle of the back as suggested by PUSH. Our app has a video showing the band worn on the pelvis, as that is where it is designed to be worn. Images of placement would help users to understand. This could explain differences seen in jump height similar to the discussion around GA. Regardless still great to see how well the other metrics hold up when the PUSH band is worn on the torso!

      We acknowledge this fact and we decided on the rib placement to align the placement of the device with the cable transducer position on the vest worn over the PUSH. Thank you for raising this point. There will be a photo of the torso placement as an Annex. Indeed, the PUSH did hold up in this anatomical position. The methods will be reworded to clarify this point in the updated version of the paper.

      3) In fig 4. it is incorrectly stated our app is subscription pay only. Our app is, and always has been free. Anyone can go to apple store right now and download app for free. There is a web-based desktop software (PUSH Portal) that allows users to program training and export data among other things. This is subscription based. Please clarify which you are speaking of?

      Again, thank you for highlighting this. Indeed, that was meant to refer to the PUSH Portal for coaches. We will clarify that point in the Figure 4. again.

      Thanks again! We will address the above queries and have an updated report submitted to the SPSR team.

  2. I found very similar results when using the 2.0 Push band. Comparing with My Jump 2, it has overestimated jump height by 11-13 cm over 10 countermovement jumps.

    • It was a legacy code from an initial Band 1.0 validation that wasn’t redone until recently with the release of 2.0. If you looked at flight time (via export) you’d notice must closer data (i.e., almost perfect vs FP). The issue was a correction factor used in JH estimation from flight time, as the flight time event detection in band 1.0 wasn’t as good. You’ll find this fixed in the next PUSH app update, since with Band 2.0 we don’t need the correction factor anymore because the hardware does a much better job at detecting the signals. There will be a correction equation to fix all of the previous data as well, I will be doing a post on our website about this. This is where external research like the study above can help to find gaps in the product, in this case highlighted an issue which we can turn around and fix rather quickly. Thanks for your input!

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