Problem reading a GPX file

[V.V.V.]

So if you're using that extension you have to convert to m/s.

Fine, right again. Thank you  
Easy to solve dividing.

What data do you mean? You might want to check the XML Schemata if've collected for the various GPX extensions: https://github.com/cpesch/RouteConverter...c/main/doc

One question more abusing of your patience .
If I have understood well this documentation, in order to include the track stats, respecting the gpx standard and without disturbing the reading of the RC file, the gpx text must be like:
......
    <trk>
       <gpxtrkx:TrackStatsExtension xmlns:gpxtrkx="http://www.garmin.com/xmlschemas/TrackStatsExtension/v1">
           <gpxtrkx: Distance>Total distance en meters</gpxtrkx: Distance>
           <gpxtrkx:TimerTime>Total time in Seconds</gpxtrkx:TimerTime>
           <gpxtrkx:MovingSpeed>Average Speed in MetersPerSec_t</gpxtrkx:MovingSpeed>
           <gpxtrkx:MaxSpeed>Max Speed in MetersPerSec_t</gpxtrkx:MaxSpeed>
           <gpxtrkx:Calories>Calories in unsignedInt</gpxtrkx:Calories>   
            <gpxtrkx:AvgHeartRate>Avg Hearth rate in PerMinute_t</<gpxtrkx:AvgHeartRate>
            <gpxtrkx:MaxHeartRate?>Max Hearth rate in PerMinute_t</<gpxtrkx:MaxHeartRate?>          
        </gpxtrkx:TrackStatsExtension>
        <trkseg>
            <trkpt lat="40.139935" lon="-6.032712">
                 <time>2018-08-23T10:59:05Z</time>

......
Thank you for your aide ... the ONMove-Geonaute 500 users we are very grateful to you.