I am having hard time keeping up with the backs in the rugby game. I also come home sore in my legs and feet when I practice rugby. I keep on slipping in the rugby field. What should I do to improve my performance?
you might just need to do some hard running (fartlek) on your own time, if speed is the issue sprints and an agility ladder will help - also, be sure you take a light jog around the field and stretch before practice, then do a more comprehensive stretch after practice is over do some type of a cooldown with lunges across the field or something - if your feet are sore you may just need to break into your rugby boots and give them time to adapt or look at getting a good fitting pair
Try running on sand, Ie a dry beach or up and down dunes....that give you a really good work out 'cause of the extra drag or perhaps try and make a tyre-drag and do sprints with it. It's good for getting the power back into your spint.
In terms of stamina I always used to run laps of the pitch and do the old jog along the sideline/sprint along the goaline drill.