Why does my moving speed and my average speed way faster then my max speed?

RobertoBerardo said:

Which one is more reliable?

The Max Speed and Pace are credible for a sprint. The average values are definitely wrong. Possibly due to some GPS errors, skipping tracks, pausing, or something similar. Hard to tell without seeing the data. I recommend reporting it to the Support.

... actually, I see only now that the activity is only 8 seconds long, so I guess that's the reason. It may be too short to get some reasonable averages. Although the app could certainly handle it better, in real life nobody really cares about 8 seconds long activities, so it does not seem to be anything dramatic. 

Next time you want to record just a short 50m sprint, rather do it within a longer activity, and just delimit the sprint as a lap (use the lap button). You can still report it to Garmin - they may be interested in fixing it anyway.

Thanks

Same thing happened in my activity. Trux’s comment about being too short might be the cause, although in my case it’s a 6 second lap.