Doctor of Philosophy
School of Health Sciences
Janssen, Ina, The influence of sex and skill level on patellar tendon loading during landing, Doctor of Philosophy thesis, School of Health Sciences, University of Wollongong, 2013. http://ro.uow.edu.au/theses/4257
BACKGROUND: Repetitive, high patellar tendon loading has been associated with the development of patellar tendinopathy, the most common overuse knee injury incurred in sports with a high volume of jumping and landing, such as volleyball. A large patellar tendinopathy prevalence discrepancy exists between male versus female players and highly skilled versus skilled players. It is unknown, however, how sex and skill level influence the patellar tendon load generated during landing. It is possible that male and/or highly skilled volleyball players utilise a landing technique, or exhibit specific risk factors, that contribute to high patellar tendon loading, thereby increasing their susceptibility to developing patellar tendinopathy, although this notion remains unexplored.
THESIS AIM: The primary purpose of this thesis was to investigate the influence of sex and skill level on patellar tendon loading generated when volleyball players land from a sport-specific lateral stop-jump block movement.
METHODS: To achieve the thesis aim, a cohort of 50 male and female volleyball players of varying skill level underwent assessment of known patellar tendinopathy risk factors including their anthropometry, training history, lower limb muscle strength and extensibility, and maximum vertical jump performance. Each participant’s landing technique was also characterised by assessing their three-dimensional trunk and lower limb kinematics and kinetics, and the neuromuscular recruitment patterns from six lower limb muscles. Patellar tendon loading was characterised by peak patellar tendon force and patellar tendon force loading rate during the landing. Results were analysed as a series of studies, each designed to systematically contribute to the thesis aim.
RESULTS: The interaction of sex, quadriceps muscle strength, ankle dorsiflexion velocity, and trunk flexion velocity were able to estimate and predict 52% of the peak patellar tendon force and 70% of the patellar tendon force loading rate variance generated during landing, whereby being male, and having increased quadriceps muscle strength, increased ankle dorsiflexion velocity and trunk flexion velocity were associated with higher patellar tendon loading (see Chapter 2). When matched for jump height, however, there was no significant difference in patellar tendon loading between the male and female volleyball players (see Chapter 3). Although male and female players displayed significantly different neuromuscular recruitment patterns, these patterns were not strongly related to the generated patellar tendon loading (see Chapter 4). Furthermore, although there were no between-skill level differences in landing technique or patellar tendon loading, highly skilled male volleyball players reported a higher training volume than the skilled volleyball players (see Chapter 5).
MAJOR CONCLUSIONS: Patellar tendon loading generated when landing from a lateral stop-jump block movement was not influenced merely by sex, as male volleyball players generated higher patellar tendon loading as a result of the higher jump height they attained compared to the female players. However, female players who attain similar jump heights to their male counterparts may be equally susceptible to developing patellar tendinopathy as they generated similar patellar tendon loading to the men. Furthermore, skill level did not influence the magnitude of patellar tendon loading during landing, suggesting that the discrepancy in patellar tendinopathy prevalence between the highly skilled and skilled players is due to the high training volume the highly skilled players are exposed to. Based on these findings, it is recommended that injury prevention programs aimed at reducing the patellar tendinopathy prevalence in volleyball players should focus on monitoring each player’s jump height and landing training volume, especially for highly skilled, male volleyball players who perform many jumps across frequent training sessions.