Metal Gear Solid 2: Sons of Liberty HD Edition Tips

Increase Grip Strength
Press L2 + R2 when Raiden is hanging on a ledge to do pull-ups, do 100 of these and you will increase your grip strength and will be on Grip Level 2, do another 100 to get to Grip Level 3. You cannot get Grip Level 4, as Campbell will tell you are neglecting your duties and need to get on with the mission.