There is a two-point answer to this question. It is good practice to keep the hook grip whenever snatching or cleaning a weight. However, very rarely, it may not be the best choice.
The only time I would not suggest using the hook grip is for high repetitions of snatches or cleans within a WOD, especially when the weight needs to go overhead then back to the floor extremely fast. Other than that, I suggest using the hook grip, especially while lifting heavy weights.
To secure the hook grip, the athlete needs to grip the barbell and place one, two or three fingers around the thumb. Most athletes prefer the method shown here: two fingers placed over the thumb, with the thumb protruding slightly between the middle finger and ring finger.
The hook grip is important because it helps keep the bar from sliding into the fingertips during the second phase (explosion phase) of the pull. The thumb helps keep the bar locked in place during the huge acceleration that is generated into the barbell during this phase.
Many people attempt to hook grip the barbell but stop shortly after due to pain in the thumb or the inability to hold the thumb in place. There are a few methods you can use to help solve this problem.
First, the hook grip is usually painful and awkward for only a few weeks. After a few weeks, the body tends to adapt the new grip, and sooner than later, you won’t even realize that you naturally grab the bar with the hook grip. One method to help speed this process is to hook grip a dumbbell in each hand and do farmers walks once a week for a total of 5 minutes.
Another common problem is that athletes feel the hook grip sliding out. There are two solutions to this problem. The first is to tape your thumb like so:
This tape will allow for additional grip for your fingers to hold. This is especially helpful if you have small hands. Make sure to use a tape that is very flexible and be sure to only use a minimal amount.
Another method to solve the problem of the hook grip sliding is to grow your thumbnail out . I know this sounds odd, but many weightlifters are known to purposefully not cut or bite their thumbnail, solely because they feel it helps out with the hook grip.
The hook grip is utilized for all lifts below the shoulders. On the clean, the hook grip is most commonly released when receiving the bar in the front rack. It is not suggested that you jerk with a hook grip because this can restrict the movement of the barbell while traveling overhead. On the snatch, you can either keep the hook grip throughout the lift, or you can release the hook grip on the turnover above the head. This is the choice of the athlete as to which feels more comfortable— neither is right or wrong. Most importantly, the hook grip should be utilized for cleans and snatches, especially when lifting heavy.
Get into the practice of using it early, and it will just be one more tool in your toolbox to give you that extra advantage.