The first lesson coaches and athletes should understand is that most volleyball players do not land, they fall, and if the ground was not there they would just continue falling.
Simplifying the task to allow for the athlete to learn to land safely and effectively is important, but doing so reduces the challenge and does not reflect the more complex demands of jumping and landing performance in volleyball. This is often a necessary first step, but there are more layers to this issue that must be addressed. If they are not accounted for in the design of the training program, there will be limited transfer into volleyball performance.
There are realities that come with being performance-oriented, notably the issue of single-leg landings (i.e. "single-leg falling") and the epidemic level of ACL injury, versus the general health bias of non-athletes. However, developing an improved understanding of vertical jump performance in volleyball means taking this issue, and others, and moving from simple to complex through development until we can make everything simple once more.
The load absorption characteristic is important in that:
it refers to both jumping from a better position, with greater power (i.e. roughly force x velocity)
understanding how to best absorb impact and landing forces in volleyball.
Jumping and landing strategy will be influenced by the complexity of the game and the full context is required before determining a good versus bad strategy for each (e.g. a single-leg landing is, in fact, a good strategy versus not landing at all and falling over one's self). So, while single-leg strength is important, it is far more important to understand that athletes need to know how to be athletic, and that they often must be capable of doing so on one leg.
A primary benefit of a good, foundational landing strategy is that it should perfectly mirror the loading position for a vertical jump. This is important and greatly simplifies our developmental strategy. The hard thing about this is getting athletes to understand how to do so at velocities that will both reflect the demands of jumping in volleyball and force an adaptive response that will support performance and durability. The easy thing about this is it is basic physics: every action produces an equal and opposite reaction.
But there is a second layer to this: our bodies are designed to absorb and adapt to stress according to the overload and specificity principles.
If we load the jumping position, hard and fast, we will jump from that position with greater force rapidly, but due to this adaptive capacity our muscles and joints will become more powerful and over time will be able to do this with even greater power. This is what I refer to as a short and long curve. The short is the correct focus and execution in the movement, that of playing explosively in jumping and within the sport, and the long is the body adapting to this input and growing a resiliency that further supports performance and durability. This intent is a catch all for excellence throughout development.
One key component of load absorption is tissue quality, with respect to joint motion (mobility and stability) and to those joints ability to support greater forces (load tolerance).
These are principal considerations in the development of any good training program. First, we have to be able to achieve the correct positions throughout every stage of our training. Assuming universal competency in athletes being able to achieve these positions on day one is foolhardy. Assessing athletes' capabilities in these more challenging athletic positions does not have to be complex.
Start with a basic assessment of movement skills and one simple heuristic for introducing more complex skills is, "Correct, slow, and then fast." Second, if we can achieve good position we must then develop both the power to support those positions and the capacity to do so repeatedly specific to the demands of the sport. Understanding how to do so properly within even a single vertical jump performance has important lessons for it in how force, power, and velocity characteristics are integrated and sequenced with respect to normal training timelines (Figure 1).
Figure 1. Vertical jump force (red line), power (light blue line), and velocity (dark blue) relationships. Following the red line, we see that there is an unloading effect following the start of the movement, the first orange circle on the left, and this is followed by a rapid increase in force as the athlete creates more stretch-load as they lower into a good jumping position (the slope of the red line here is what is referred to as the rate of force development and is an important differentiator for jumping performance).
Following this phase, which is colored in a light blue background shade to distinguish the eccentric/loading phase, the athlete reverses direction and begins producing force as explosively as possible. It is at this point that power often, but does not always, achieve its peak for the movement as they combine an active and forceful push against the ground with an increasing velocity as they gain a positional advantage over gravity.
As the athlete increases velocity their force decreases as they have less and less time to produce it as they prepare to leave the ground. At take-off, the athlete achieves peak concentric velocity and the athlete has successfully jumped. Upon landing the athlete makes an impact with the ground at very high velocity and how well they absorb these forces will impact the eccentric power achieved here (high eccentric force with high negative velocity, i.e. downward velocity).
We need this information from the landings to understand what the maximal forces an athlete will have to accept in the sport as this has important implications for the development of the training program. With a dual force plate system, as was used to generate this image, via the ForceDecks software, we can also gain tremendous insight into asymmetry relationships (indicated here with the yellow and green lines).
A good landing should perfectly mirror the loading position for a vertical jump. This greatly simplifies our developmental strategy and teaches athletes how to effectively absorb and adapt to the stress of jumping.
Getting athletes to understand how to both load a jump and land at speeds that reflect the demands of jumping in volleyball, to force an adaptive response that will support performance and durability, is the challenge. Ideally this should happen both on the volleyball court and in the weight room. The weight room is one of the best and safest ways, provided there is adequate supervision and instruction, to overload athletes in a way that benefits performance and supports durability. Remember, availability is one of the key abilities. Athletes do us no good on the court if they are injured.
The easy part is that it is basic physics: coach the intent to be fast and explosive in jumping and landing and that is what you will get (i.e. the Pygmalion effect).
Coaches and athletes understand the explosive side of this in jumping, and often influence it to great effect, but neglect that lesson with the landing. We create a fast and hard "push" action to jump. But, because we have competition in the air we have to consider that landings often have to happen at the last possible moment. This means athletes must learn to land explosively! So, teach a "pull" action back towards the floor to put themselves in the best possible body position in consideration of the limited time and attention.
Achieve the correct positions first through each stage of training. Develop both the power (force x velocity) to support those positions and capacity to do so repetitively. Good eccentric power, i.e. stopping and decelerative power, should be an early target and can be achieved with good double and single-leg hopping and jumping exercises that emphasize speed and force absorption. For example, a good landing is like a plane landing on the runway we do not want to disturb the passengers. The second layer to this, and an area to progress towards, is landings in volleyball are more like jet landings on an aircraft carrier: we have limited space and time, and we have a lot of speed coming into it.
In volleyball, there are two principal landing conditions: impact and decelerative landings. Impacts occur at high knee angles (less flexed) with increased stiffness and joint stress. Decelerative landings occur at both higher and lower knee angles and occur when there is an active stopping motion applied by muscles and joints. We need the joint integrity to tolerate both in volleyball. The intent is always to decelerate but the strength and conditioning program should account for being strong and powerful enough for both. Putting strength training simply: being strong will not always make your athlete a great jumper, but being weak will always make them a liability.
There is a complementary relationship that occurs in how skill and performance is coordinated in an athlete's development. This goes across what is referred to as the slow stretch-shortening cycle (SSC) and the fast SSC, across maximal strength and explosive/reactive strength, through "short and stiff" jumpers (who jump and land in higher knee angles) and "long and strong" jumpers (who get lower into jumps and landings), through rigid and elastic tendon function, etc. To maximize this complementarity, it is important to understand that stress is unlimited, recovery is not. When full recovery is not an option understand that a change is nearly as good as a rest. Monitor your athletes, sequence and vary training loads both systematically and fluidly, and integrate volleyball programming with other support staff to maximize team and athlete performance. Carpe diem.