How Isometric Training Works
The most basic way to get stronger is to work against a load that is “maximal” for just one or two repetitions. Training close to one’s max yields the greatest gains in strength, but there is a major problem: The body can’t take it. Working with maximal loads takes a massive toll on the muscles and nervous system, and it also risks injury to joints and tendons with intense repetition. Moreover, recovering from training with heavy weights can take 72 or more hours, whereas training with a more moderate weight only requires about 24 hours to recover.
This is particularly true in isometric (static) training, where the exercise involves holding a muscle in a static position, like planks, wall sits, or hangboarding. Isometric training simply teaches the muscles to get strong in a fixed range, where the muscle is not significantly lengthening or shortening during the set of work. This is in contrast to more “traditional” modes of training, called isotonic training, that involve concentric and eccentric contractions. Closing the elbow and bringing the weight up in a bicep curl, which shortens the muscle body, is a concentric action. The eccentric action is the opposite, where the muscle is allowed to lengthen under load, or opening the elbow in a bicep curl. Isometric action would simply be holding the elbow in one position, say a 90° bend. Although all three actions are used in most movement, climbers generally hold the fingers in a fixed position
Second joint is below the level of the first joint on a large edge or sloper; requires least amount of effort. once they grab the rock, making isometric training the most useful for finger strengthening.
Several studies on isometric strength have shown that the total volume of load (time hanging) is more important than the degree of load (weight). Using varying percentages of maximum weight and adjusting the total time each athlete worked under load, these studies demonstrated that it matters less how hard the muscles were worked than how long muscles were under tension. In one study, the team showed that seven one-minute contractions at just 30% of maximum resulted in a strength increase of about 30% in just six weeks. Similar studies showed that it’s possible to gain just as much strength at slightly reduced loads (65 to 75% of maximum) as one might gain while training at maximum (more than 90%) effort. Clearly this is the better method for most climbers, as it provides faster recovery between sessions and minimizes injury risk to sensitive fingers. Second and first joints are even on a hold; requires moderate effort. Second joint is above the first joint, requires most effort.