Association between Trunk Muscle Endurance and Static and Dynamic Balance, Landing Mechanics, and Upper Limb Functional Stability in Adolescent Female Volleyball Players with Different Levels of Neuromuscular Deficits Identified by the Tuck Jump Assessment
This study demonstrates that in adolescent female volleyball players, greater trunk muscle endurance is significantly associated with superior static and dynamic balance, landing mechanics, and upper limb stability, with athletes exhibiting lower neuromuscular deficits (as identified by the Tuck Jump Assessment) showing significantly better performance across all these functional measures compared to those with higher deficits.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Volleyball is a game of explosive power and precise timing. Players launch themselves into the air, strike a ball with their arms, and then crash back down to the floor. To do this safely, the body must act as a single, coordinated unit. If the connection between the legs and the arms breaks down, the risk of injury rises sharply. At the center of this connection lies the trunk, the core of the body that includes the muscles of the abdomen and back. These muscles do more than just hold the spine upright; they act as a bridge, transferring force from the ground up through the body and out to the hands. When these muscles are tired or weak, that bridge becomes unstable. The body wobbles, the landing becomes clumsy, and the joints, particularly the knees, take on dangerous amounts of stress. For young female athletes, who are already at a higher risk for certain knee injuries, understanding how well their core muscles can hold up under pressure is a critical piece of the puzzle for staying healthy and playing well.
In a recent study, researchers set out to see how the endurance of these trunk muscles relates to the way adolescent female volleyball players move. They wanted to know if players who could hold their core muscles steady for longer periods also landed more safely, balanced better, and controlled their arms more effectively. The team gathered sixty female players, all between the ages of fifteen and eighteen, from a local sports program in Iran. To sort the athletes into groups, the researchers used a specific test called the Tuck Jump Assessment. In this test, a player jumps up and pulls her knees to her chest repeatedly for ten seconds. Observers watch closely for mistakes, such as knees knocking together, the trunk twisting, or a heavy, uncontrolled landing. The researchers divided the players into two groups based on how many errors they made: one group with fewer errors, indicating better movement control, and another with more errors, suggesting greater difficulty in managing their bodies in the air.
Once the groups were established, the scientists measured the players' physical capabilities in several ways. They tested how long each athlete could hold specific positions to measure the endurance of their trunk muscles. One test required holding a semi-sitting position to check the front muscles, another involved lying face down to test the back muscles, and a third required balancing on one side to test the muscles on the flanks. They also measured how well the players could stand on one leg without moving, how far they could reach in different directions while balancing, and how they landed after a jump. Finally, they assessed the stability of the upper body by having players push and reach with their arms while holding a plank position. The goal was to see if the strength of the core muscles showed up in these other tests.
The results revealed a clear and strong connection between the ability to hold the core muscles steady and the quality of movement. The players who made fewer mistakes during the jumping test also demonstrated significantly better endurance in their trunk muscles. They could hold the difficult positions for much longer than the players who struggled with their jumps. For instance, the group with better movement control held their side-bridge position for an average of over forty-four seconds, while the group with more movement errors managed less than twenty seconds. This difference was not just about the core; it extended to how they moved their entire bodies. The athletes with stronger, more enduring core muscles landed more softly, kept their balance more easily, and reached further with their arms without losing their stability. The study found that the muscles on the sides of the trunk showed the strongest link to how well a player landed and maintained balance, suggesting that the ability to stop the body from swaying sideways is just as important as the ability to hold it straight.
Perhaps the most surprising finding was that the endurance of the trunk muscles was also linked to how well the players controlled their upper bodies. In volleyball, the arms are used constantly to hit and block, but the study showed that the stability of the shoulders and arms depends heavily on the strength of the core. Players who could hold their trunk muscles steady for longer were also better at maintaining their balance while reaching with their arms. This supports the idea that the body works as a continuous chain, where the stability of the middle section dictates the performance of the ends. If the core wavers, the arms struggle to find a stable base to work from. The researchers noted that while these findings show a strong association, they do not prove that building core endurance will automatically fix movement problems or prevent injuries. However, the data suggests that checking how long an athlete can hold their core muscles steady, alongside watching how they jump, could provide a clearer picture of their overall movement health.
The study concludes that for young female volleyball players, the ability to keep the trunk muscles engaged over time is a key factor in how safely and effectively they move. Those who showed better control during the jumping test also had stronger, more enduring core muscles and performed better in balance and landing tasks. The side muscles of the trunk appeared to be particularly important for keeping the body aligned during these dynamic actions. While the research does not offer a guaranteed solution to injury prevention, it highlights that the core is not just a static support but a dynamic engine for movement control. By paying attention to how long these muscles can work before fatigue sets in, coaches and trainers may be able to identify players who are at risk of developing poor movement patterns. This could lead to more targeted training that helps young athletes build the specific kind of endurance needed to keep their bodies stable, their landings safe, and their games strong.
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