A guy I know who is joining the infantry in june has a problem with his left knee or so he thinks. Can anyone help him. The reason I am asking is that he is not a member. If he bends right down with all his weight then stands up you can hear a very quiet sort of cracking/grinding noise. Is this significant or is he being a little too worried about training and medical tests. Just in case you wonder what his training is he runs most days of the week, gym work 3 times a week and swimming a mile once a week.