I cannot get sprint to work with shift key or any other key. If I tick the box in options for always run this makes no difference.
I have seen an error in dev console about not being able to write to userconfig but I think this is a red herring.
This is using the latest version of black mesa downloaded 22/11/2012
windows 7 64bit
installed in correct folder under steam apps.
using microsoft wired keyboard 600
error with userconfig here aswell, but Gordon runs
In Options > Black Mesa - Gameplay tab, make sure ‘Enable always run’ is unticked. Also one thing I initially overlooked was ‘shift’ which was originally set for ‘Sprint’ only applies to the left shift button. I had to select ‘RShift’ to make this work.
I have manually changed the key for sprint but it does not seem to do anything. I have tried this with the always run box ticked and unticked, it does not seem to make a difference. Its a real shame because the game looks amazing, I bought halflife source hoping it would be something like this. Without being able to run It makes the game impossible to play properly 
Maybe there’s a problem with the source files. All I can suggest, if you haven’t already, is to re-download it from another site or torrent. Good luck.
I think I was running it just seemed slow. The sv_maxspeed was set at 450 the default. I just think that the sprint bind button is not working so as long as I run every where its ok. The game is great and its a little different from the origional.
I used this custom setting
https://forums.blackmesasource.com/showpost.php?p=494526&postcount=5