It seems that no matter how high, or low, you vault all anyone comments on is whether or not your bottom arm is collapsed. Should you care? Probably not as much as the rest of the vault community, but you should probably care about your bottom arm only as much as you care about your pole carry, running mechanics, plant, jumping mechanics, swing etc. Although I don’t think a vaulter should have a collapsed bottom arm I do not think the emphasis that the vault community puts on it is not as important as they think.
The problem with placing too much emphasis on any one aspect or moment of the vault is that you may sacrifice phases before or after the aspect you are focusing on. Every phase of the vault has an important role in setting up the phase that follows and produces a full jump. Let’s use the plant as an example, if for example you want your athlete’s plant timing more consistent you may tell them to have a low pole carry so that they don’t have to worry about the timing of the pole drop. Now that might produce a more consistent plant but you are sacrificing runway speed due to the athlete dealing with the added carry weight. So the benefit of more consistent plant timing is negated by the fact that you cannot run with max speed.
So why do so many people focus on the collapsed bottom arm, and how can that emphasis have a negative impact on the entire jump? Some aspects of the vault are not easily seen unless you have a trained eye, but anyone can see whether or not your bottom elbow bends at take off. Some people who lack experience pick on this aspect because they will often point out a professional vaulter who doesn’t collapse their bottom arm and explain to a beginner or novice vaulter that the difference between a novice athlete and professional is the bottom arm (of course there many differences between a novice and a pro, years of experience and tremendous athleticism to name a few), and if only the novice vaulter could keep their arm extended they too could jump much higher? So due to lack of experience, or just laziness as a coach to address all aspects of the vault coaches will key on this. Why even watch the run, catch a mid mark, pay close attention to the pole carry and plant, or watch for any passive phases in your vault when you can just tell an athlete whether or not they collapsed? What’s easier?
There is some truth to the importance of an extended bottom arm, but the extended bottom arm has to come together with all the phases of the vault working together. If an athlete blocks out, locks their elbow and forces their arm to remain extended, they will prevent their center of mass from rising, slow down their swing and lose the ability to clear bars above their grip. Often times male athletes contact me who are gripping 13’ or 13’6” but they only jump 12, female athletes will contact me and grip 11’ and jump 8’. If these athletes can grip that high there is no reason they cannot clear bars at or above their grip. (Always subtract 8” from the grip to account for the box. 11’-8” =10’4”)