The Case Against Max and Sub-Max Drop Landings: Jump-Landings For the Win!
I've never understood why so many researchers and practitioners LOVE the drop-landing so much. Moreover, I've never understood why drop-landings are used for any reason from heights equal to or less than an athlete's jump capacity (i.e., maximum jump height). It makes zero sense to me. Yet, a quick search on Google Scholar returned well over 5,000 publications in which the drop-landing was studied. For those of you less familiar with the drop-landing, it's a movement task where an athlete begins standing still atop a raised platform. The athlete then reaches one limb forward to initiate the landing, after which they attenuate the impact forces upon ground contact and complete the task by returning to a standing still position. To be clear, I am talking about landings on two feet (i.e., bilateral landings).
The Bone I Have To Pick With Drop-Landings
Now that I'm well-over 10 years older than my undergraduate students, I need them to teach me the hip slang so I can stay trendy. They might say my absolute hatred of sub-maximal and maximal height drop landings is "extra" (or over the top and dramatic). Nonetheless, here's a couple reasons to explain why I have a major bone to pick with the sub-max to max-intensity drop-landing (Note: I am not hating on drop-landings performed from responsibly selected super-maximal heights - see later on in this post). First, it's no better at controlling the fall height during landing than a Vertec. We demonstrated this in two publications from my early doctoral dissertation work (Harry et al. 2017; Harry et al. 2018). More recently, we provided follow-up support for the jump-landing when we successfully used the Vertec to control vertical jump-landing height when exploring how different foci of attention effect landing biomechanics (Harry et al. 2019). Second, and perhaps more importantly, impact forces are not consistent between drop-landings and jump-landings when performed from heights equal to maximum jump height (Figure 1).
Figure 1. Forefoot impact forces during vertical jump-landings and step-off style drop landings from equal heights.
Notes: Data are presented as mean + standard deviation across a sample of males of females.
What's more is that the loading rate, which is commonly studied in relation and/or linked to overuse musculo-skeletal injury, is greatest during the drop-landing and a smaller change of momentum occurs during the loading phase of the drop- versus jump-landing (Figures 2 & 3, taken from Harry et al. 2017 & Harry et al. 2018). This is important because the loading phase (typically the first 80-100 milliseconds after ground contact) is commonly reported to be the time when catastrophic injuries occur (e.g., ACL or achilles tendon rupture). The change of momentum result might be a bit more difficult to process than loading rate. The rationale for wanting a greater amount of impulse during the early part of landing centers on the fact that it is ideal (in my mind) for us to have athletes prepared for ground contact such that the involved musculature contributes to energy absorption as soon as possible. This is because a delay in contribution would suggest that the more passive structures (e.g., ligaments) are force to absorb most of the energy. If more impulse (i.e., the effort applied to change and stop downward momentum) is applied in the early stage of the landing, it's likely that the musculature contributed more effectively so that the impact forces were spread out over a longer period of time, thereby shielding the passive structures from unnecessary stress. Basically, drop-landings likely inadvertently increase the amount of stress experienced by passive structures (I say likely because we can't actually measure passive tissue loading in a living human). Personally, I am not willing to accept this likelihood based on a false perception of "having more control of the landing height."
Figure 2. Differences in loading time between jump landings (VJL) and drop-landings (STL) from equal heights.
Notes: The magnitude of peak force was not different between the tasks, so reduced loading time reflects an increased loading rate.
Figure 3. Differences in vertical impulse during the loading (ground contact to peak impact force) and attenuation (peak impact force to end of downward motion) phases between vertical jump landings (VJL) and drop landings (STL).
Notes: *: greater than STL (p < 0.05); #: greater than VJL (p < 0.05).
Am I Alone Here? Is This A Hill I'll Die On By Myself?
Now, I must say that I am not the only who thinks drop-landings should be cautiously used. For instance, at least three different research teams (four if you count my own) have sought to determine the usefulness of drop-landings as a surrogate for vertical jump-landings (see Collings et al. 2019; Afifi & Hinrichs, 2012; Edwards et al. 2010). The general consensus is just what I've been harping on thus far in this post: drop-landings are not a valid representation of landings following a jump. Of course, there are situations where it would be necessary (mostly) to use a drop-landing. For instance, there are some wickedly-crazy parkour folks out there who routinely drop from elevated heights and they must be able to attenuate impact forces from those super-maximal heights (relative to their jump capacity). In addition, there's this commonly accepted training principle called "overload." We simply cannot over-load athletes sufficiently during jump-landings because (a) they can only jump, and therefore land, from 1 maximum height and (b) adding external mass actually reduces the jump height, relative impact forces, and mechanical work done. When we consider absolute magnitudes of the kinetic metrics, I don't think the increases are worth their salt as it relates to driving real change. If we were to increase the external load so much that the impact forces and mechanical work increased to a useful level and could drive positive changes in certain landing metrics, the time duration of the landing would increase so much that it would likely be more costly than beneficial (athletes need to land attenuate force quickly right?).
Therefore, sporadic, purposefully-planned implementation of drop-landings can be an effective way to stimulate targeted adaptations. But, drop-landings should be secondary to jump-landings in most research and practical training scenarios.
That's all for this week. Thanks for stopping by, and I hope you'll back for next week's installment of the "Fun Friday Research Blog." Deuces.