The strength of your grip comes from many genetic variables; tendon thickness, origin and insertion of tendens, bone length, muscle length, muscle twitch fiber type…but much of your success on a problem deals with economy – mental, technical and physical. Mentally, if you cannot conceive of the correct 3 dimensional movements, have fear of pain or failure, or understand how to pull with other muscles besides the ones attached to your fingers – then you’re not being economic. Technically, if you position your body correctly on a difficult move, you are giving yourself a mechanical advantage to reach farther or with less effort – therefore improving your economy on your grip. Physically, if there is a weak link in the chain of musculature from your fingers to your toes, you may not be able to position yourself correctly, making you biomechanically less economic.
Bouldering is the best training for your bouldering because it requires you to develop these three aspects. But, it may not be the best way to measure your grip strength progression. Technical flaws or not reading the sequence to the problem correctly may be a reason for not sending a problem, or you may perceive it as arm pump or some other weakness. Some of you may be surprised to find just how strong your fingers are – only to realize that some other aspect is in relative weakness to your finger strength. There are so many factors that create a successful latch onto a hold; were you in the right position, did you read the sequence correctly, are you mentally focused, do you have weak core strength, is your foot angled correctly on the heel/toe hook etc., making it is difficult to pinpoint why you didn’t send. Many would say that they didn’t have the finger strength to stick the hold, but that may not be the case. The athlete may have a weakness in the muscular chain tension from their grip to their toe contact.