Abstract
The state of muscle architecture is determined through the properties of skeletal muscle during dynamic muscle contractions. In addition, the structure of muscle architecture directly influences the muscle’s ability to generate force and velocity. Muscle architecture comprises of three prominent components, namely: muscle pennation angle, fascicle length and muscle thickness. More specifically, the pennation angle has been reported to have an influence on force production and fascicle length change has been associated to the velocity of contraction. It has also been widely reported that muscle thickness and an increased muscle cross-sectional area are related to the increase in force production and overall muscle strength. The muscle pennation angle located between the fascicles, is the structural property of the whole muscle that directs muscle function of an individual. Additionally, muscle adaptations and changes in muscle architecture occur as a result of the training regiments and the mechanical demands of a sport code. Furthermore, the aim of this research study is to assess the relationships between lower limb muscle PAs and physical performance parameters in female netball and football athletes.
This study identified and assessed the associations and relationships between lower extremity muscle pennation angles and physical performance in female netball and football athletes. The data was collected for 22 netball (n=11) and football (n=11) athletes from the University of Johannesburg (age: 21.1 ± 2.1 years old; stature: 165.3 ± 7.9 cm; body mass: 59.6 ± 8.0 kg). Ultrasonography was used to assess muscle architecture, specifically pennation angles, (bicep femoris, gastrocnemius, rectus femoris, tibialis anterior and vastus lateralis) in flexed and extended states. Physical performance parameters: vertical jump test (37.2 ± 6.9 cm), sprint and acceleration test of 10m (2.1 ± 0.3 s) and 40m (5.5 ± 1.3 s), change of direction (COD) ability t-test (12.3 ± 1.3 s) and one repetition maximum (1RM) leg press (169.3 ± 42.0 kg) were evaluated.
Statistical analysis was performed to determine any significant relationships and correlations. All tests performed were set at a significance level of p 0.05. An independent samples t-test was performed to compare means of physical performance parameters and muscle pennation angles of netball and football athletes. A paired samples t-test was also conducted for limb comparisons between right and left lower extremity muscle pennation angles in flexed and extended states. Moreover, a Pearson’s r correlation coefficient was performed to assess
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the strength of linear relationships between muscle pennation angles and physical performance parameters of netball and football athletes.
The independent samples t-test presented notable differences regarding netball and football anthropometrics and physical performance parameters. Significant differences were observed between the stature (p = 0 .028), body mass (p = 0.008), 10m sprint (p = 0.005), 40m sprint (p = 0.000), and COD ability t-test (p = 0.000) between the respective sport codes. The results also displayed significant differences between netball and football athletes regarding the tibialis anterior pennation angle in the left extended (p = 0.003), right extended (p = 0.000) and right flexed states (p = 0.001). The paired samples T-Test between the left and right lower extremity only presented significant differences in the vastus lateralis flexed state (p = 0.047). The correlation coefficient presented small to moderate relationships amongst pennation angles and performance parameters. However, the correlations displayed high to very high relationships between the tibialis anterior pennation angles and physical performance parameters. Specifically, there were high correlations between the left tibialis anterior pennation angle, COD ability t-test (r = 0.564; p = 0.006), 1RM strength (r = 0.540; p = 0.010) and relative strength (r = 0.542; p = 0.009) in the extended state. High to very high correlations were also present between the right tibialis anterior pennation angle, 40m sprint (r = 0.669; p = 0.001) and COD ability t-test (r = 0.829; p = 0.000) in the extended state. Further, there were high correlations present between right tibialis anterior pennation angle, 10m sprint (r = 0.531; p = 0.011), 40m sprint (r = 0.549; p = 0.008) and COD ability t-test (r = 0.527; p = 0.002) in the flexed state. These findings could further be attributed to the changes in muscle architecture and are also associated with force production and shortening velocities in skeletal muscles during physical activity. This research study provides an overall understanding of the structure and changes of muscle architecture, which can be assessed using ultrasonography, and its association to physical performance parameters, sport demands and training protocols.
Keywords: muscle architecture, pennation angle, fascicle length, force production, velocity, performance parameters, ultrasonography.