Venu 3 gps accuracy for max speed for run. I'm not an athlete yet I got 38Km/h max speed on a sprint.

I was out the other day with my venu 3s for a walk/run.  I did a couple of 100ish meter sprints .  I am not an athlete and I don't do endurance running. Just a few light to medium jogs here and there lasting 1 to 2 kms. 

On the results it showed I had a max speed of 38.3 km/h. Which would coincide with one of the two sprints I did.   Being 40 and not training much i thought that that max speed might not be accurate seeing how an average person max sprint is 21 km/h. however, I was pushing pretty hard so unsure what to believe. 

I am just trying to see If the gps system is accurate.  I used the "all systems gps" mode. 

Thanks