Where's the Love for Standing Long Jumps (i.e., Broad Jumps)?
We All Know the Standing Long Jump, But is it Thaaaaat Cool?
I've often wondered why so many (myself included) tend to brush away the standing long jump (SLJ) when testing athletes in favor of the vertical jump. Sure, the vertical jump is sexy (don't believe me? Take a look at this recent video SportsCenter shared on social media), but the standing long jump appears to be a better indicator of sprint acceleration and change-of-direction performance potential than the vertical jump (click these for proof). Not only that, it's a key test in just about all combine events conducted by professional sports leagues, and there's more horizontal jump events than vertical jump events in track and field. Some studies have provided useful information related to the SLJ, but knowledge remains limited to the distance jumped, thereby ignoring explosive performance and the force-time strategies contributing to jump distance and explosiveness.
It's clearly time to give the SLJ some more love in the research and practical settings, don't ya think?
I'm glad we agree (with this point if you're not paying attention). But, what force-time strategies are important for the SLJ? That's yet to be explored in excruciating detail, but the "jump fanatics" (yeah, you are in this group [leader of group?]) have set a pretty good foundation for where to start because the tremendous body of work on the vertical jump translates well (I think) to the SLJ. This is because both the SLJ and vertical jump share similar execution demands (e.g., countermovement, need to overcome gravitational force and propel in the body in the air, etc.). So, my team of researchers and I set out to see if any of these force-time strategies commonly explored in vertical jump tests predicted SLJ performance (defined by both jump distance and explosiveness or the reactive strength index-modified) in hopes of identifying a pool of metrics that could be targeted in training to stimulate SLJ improvements and, indirectly, sprint acceleration and agility potential. Here's the overview of what we observed (the full article will be published at a later date in the Journal of Applied Biomechanics).
Crash-Course of the Methods
The sample we studied included 15 NCAA Division 1 men's footballers (soccer for my fellow Yanks) of various positions (goalkeepers, defenders, midfielders, attackers). They each performed three maximum effort SLJs on a force platform system, seeking to achieve maximum horizontal distance as quickly as possible. The average of the trials was used in the analysis. As you can tell, it was a really simple protocol (which is good for all of you practitioners I am convincing to add SLJs to your test battery, right?).
We used that scary-but-not-so-scary MATLAB software to write an analysis program (seriously, I learned how to use it, and I can help you learn, too) to extract numerous force-time variables within the unloading, eccentric yielding, eccentric braking, and concentric phases of the SLJ (See Figure 1 for overview of the phases).
Figure 1. Visual representation of the unloading (UL), eccentric yielding (EY), eccentric braking (EB), and concentric (CON) phases overlaid on vertical (left) and horizontal (right) force & velocity curves.
How Did We Analyzed the Data?
We used a fairly new (at least to biomechanics and sports science research) regression analysis, known as "Regularized Regression" to determine which force-time variables predicted jump distance and/or jump explosiveness. I don't want to get too deep in the nitty-gritty, but regularized regression provides advantages over other more common regression types when dealing with highly correlated variables (which most jumping variables are) and when there are more predictors that observations. Two models are returned, the minimum mean square error and Sparser models, but we used the Sparser model to interpret the data because it tends to retain fewer predictors and is thought to be more "parsimonious" (whatever that means, right?).
Did We Learn Anything Cool?
Hell yes we did. Kind of. I say "kind of" because our analysis identified 11(!) variables that were retained as collective predictors of jump distance, and 10(!) variables retained as predictors of jump explosiveness. We did not think it would be reasonable to recommend practitioners to prescribe exercises that would be expected to stimulate adaptations in >10 force-time variables at the same time. So, we tried to simplify the output by treating predictors that were also significantly correlated with the performance metric(s) as the "most useful" targets so-to-speak. I'm not sure if that's the best approach, but it's what we chose to do (and our peer-reviewers felt it was reasonable - so blame them if you don't agree!). Here's a tabular look at the variables retained as predictors for each performance metric, with the significantly correlated variables highlighted in yellow (remember - focus on the Sparser model summary).
Table 1. Force-time predictors of SLJ distance.
Table 2. Force-time predictors of SLJ explosiveness.
So What the Hell Does it all Mean?
Well, for jump distance adaptations, we think the first logical approach would be to try and concurrently increase jump height and decrease the duration of time yielding to force the gravity. Now, you might be wondering something along the lines of, "why in sweet-Jesus' name would we target vertical stuff for a horizontal movement?" Well, more vertical height = more time in the air = more flight distance (assuming the horizontal impulse stays the same). We've started noticing a slight pattern in our jumping data (vertical and these SLJ data) that what athletes do while yielding to gravity plays a fairly key role in how well a jumps will be performed. This makes sense because the only things an athlete must overcome during a typical jump test are gravity and/or their muti-axial inertia. To increase jump height during the SLJ, we caution against promoting steeper launch angles because athletes tend to display launch angles that are up to 10 degrees greater than what's considered ideal. Instead, research suggest that simple-yet-seemingly-omnipotent external foci of attention (e.g., trying to reach a object at a distance beyond their jump ability) would be a better intervention because 1) they seem to always return greater jump distance and 2) are extremely non-invasive and quick to use. For eccentric yielding time, it's difficult to pinpoint strategies to reduce this duration (because my team and I are the only group of researcher who've seemed to accept it as potentially useful - although it does take wayyyy too long to see "new" evidence in the literature so I'm not that upset about it). However, there a many exercises that can augment an athlete's downward velocity during a countermovement action (e.g., squats or jumps with bands or weight releasers) that seem reasonable for this purpose. We even have some evidence indicating that continued on-pitch training can have positive effects on yielding qualities. Hopefully this provides a good starting point for how you can approach increasing jump distance during the SLJ.
For jump explosiveness adaptations, we think that concurrently targeting anterior-posterior yank (i.e., RFD - one day I will stop including RFD here. Yank for the win!) during the unloading phase, average concentric vertical force production, and the duration of the concentric phase were should be the first targeted adaptations. Increasing anterior-posterior yank during the unloading phase is, to me, a really cool result because it emphasizes the value of axis-specific (e.g., vertical or anterior-posterior) rapid force manipulation during jumping, regardless of whether it's a vertical or horizontal jump. I've seen some interesting exercises on social media that seem like they'd stimulate this metric, but that's pure speculation. Given the fact that jump explosiveness is heavily dependent on the time of movement, it's not surprising that these data suggest improved explosiveness should also require reduced concentric phase duration. Moreover, increasing concentric average vertical force production is critical because it will offset the potentially compromising effect of reduced concentric time on the distance component of jump explosiveness (gotta love that ol' Impulse-Momentum relationship!).
I also don't what you to forget that, in addition to the variables discussed above, the model retained many more as predictors. This means you can continue to think this guy is just a know-nothing-goober and ignore this interpretation in favor of your own collection of "key" metrics to target in training. That's cool, too, and it's totally reasonable. the main thing is that we are showing some love to the SLJ, because it's time to share the love after so many negligent years spent as the "red-headed step-bother(sister)" of the vertical jump. Out from the shadows it comes!
Okay, folks, that's what you get this time. Thanks for tuning in! Hope you liked it, or at least, didn't hate it. Catch you next time!