Don't be fooled into thinking you can increase grip strength by training the forearms and hands with isolation movements like wrist curls. The forearms need both heavy work and pump work to maximize grip potential and pack on muscle. Here are exercises that'll help you forge an iron grip and killer forearms.
Reverse Barbell Curls
These are great to do at the end of your arm workout – shaving or brushing your teeth is really tough after doing these! This exercise is done with the palms facing down as indicated with the red arrow in the below photo. As I mentioned before, this exercise can make tendonitis in the elbow flare up so be careful if you are prone to overuse injuries. Start out with a really light weight and use slow deliberate form. These can be done either standing or seated, I prefer seated because it keeps you from cheating. If you stand while doing this, make sure that your torso is completely motionless. Many people tend to rock their bodies forward and back to swing and jerk the weight around. I suggest doing these at the end of your arm workout when your biceps are good and weak, that way, even though the biceps is stronger than the forearm they are both worked out evenly.
Starting Position: use an overhand grip making the palms face down.
Ending Position: Raise the bar slowly and steadily – yikes what a forearm pump. Keep it slow, 2s up and 2s down. Make sure your torso is completely stationary, no jerking or bouncing.
Seated Wrist Hammer Curls
In a seated position with your back straight, place your forearm on your thighs with your thumbs pointed upward. Use a 5-, 10-, or 20lb weight in a hammer position and lift it back and forth slowly for 3 sets of 20 repetitions. This will develop your brachioradialis muscle, which inserts at the distal aspect of the forearm at the wrist. Greater hypertrophy of this muscle will give more definition and balance of the forearm.
Palms Up Dumbbell Wrist Curls
OK, finally a forearm exercise with the palms up so we can give those poor tendons in the elbows a break. This wrist curl is similar to the above palm down dumbbell wrist curl except our palms are basically facing upward. Again, use a weight bench if you have one to rest your forearms on or sit with spread legs in a chair and rest your forearms on your quads.
Starting Position: In the down position, the wrist is drooping at about 45 degrees and your palms are facing upwards. Your hands should not be horizontal, that’s too awkward. The thumb side of your palm should be about 2″ higher than the pinky side. Now slowly raise the weight to the up position. The forearms remain motionless in this exercise, only the wrists move.
Ending Position: In the up position, the wrist is angled upward at about 45 degrees. The palms are still facing upward. Now lower the dumbbells slowly and repeat.