Hyperlordosis or anterior pelvic tilt is a common non-neutral spinal posture associated with weak core stability, low back pain and altered lumbopelvic muscle activation patterns. Yet the effects of altered lumbopelvic posture and core stability on muscle activation patterns have not been evaluated during a functional movement. The main purpose of this study was to determine the relationship between pelvic tilt, core stability and muscle activation patterns during non-weighted squats in U/19 university-level rugby union players. A total of 49 rugby union players participated in this study. Pelvic tilt (dominant side) was measured from a digital photo with clear reflector markers on the anterior superior iliac spine (ASIS) and posterior superior iliac spine (PSIS) using the Kinovea video analysis software programme (version 0.8.15). Flexibility of the hamstrings, hip flexors and knee extensors was assessed with goniometry. Core stability was assessed using the pressure biofeedback unit and muscle onset times during the ascent phase of non-weighted squats. The onset times of the transverse abdominis (TrA), erector spinae (ES), gluteus maximus (GM) and biceps femoris (BF) muscles were measured using electromyography (EMG). Players were then grouped according to pelvic tilt (anterior and neutral) and by playing position (forwards and backs). The between group differences were evaluated for the abovementioned variables using p-value (statistical significance) and d-value (practical significance) measures. Muscle activation patterns and firing order were determined using descriptive statistics. The mean pelvic tilt of all participants (N=49) was an anterior tilt of 15.35°. When grouped by pelvic tilt, the anterior tilt group showed a mean pelvic tilt of 17.83° (n=27) and the neutral pelvic tilt group showed a mean pelvic tilt of 11.75° (n=22). Despite the differences in pelvic tilt, there was no significant difference in flexibility between the groups. Another controversial result is that the anterior tilt group showed practical significantly better core stability (d=0.54) than the neutral tilt group (46.93° vs 56.3°). During the double leg squat the muscle activation patterns were consistent between the groups. TrA activated first, followed by ES. Thereafter, the BF muscle activated, followed by the GM. The first place activation of TrA is consistent with the literature stating that the deep abdominal stabilisers of individuals with good core stability activate before the movement is initiated. The early onset of muscle activity of ES points to a focus on back extension during the ascent of the squat. Because the pelvic tilt was measured during static standing only, it is unclear whether the players in the neutral tilt group were able to hold the neutral pelvic tilt posture throughout the movement. Research has shown that there is an increased focus on trunk extension during the ascent phase of the squat which is not present during the descent. Future research should focus on assessing the pelvic tilt at the beginning of the ascent phase of the squat to ensure accurate results. The delay in GM activation during the ascent of the squat is concerning. GM acts as a lumbopelvic stabilizer, and its slow activation points to a decrease in lumbopelvic stability. This is very important in weight training, because weight training increases the strain on the lumbar spinal structures, which decreases performance and increases the risk of injury. / MSc (Biokinetics), North-West University, Potchefstroom Campus, 2014

Hyperlordosis or anterior pelvic tilt is a common non-neutral spinal posture associated with weak core stability, low back pain and altered lumbopelvic muscle activation patterns. Yet the effects of altered lumbopelvic posture and core stability on muscle activation patterns have not been evaluated during a functional movement. The main purpose of this study was to determine the relationship between pelvic tilt, core stability and muscle activation patterns during non-weighted squats in U/19 university-level rugby union players. A total of 49 rugby union players participated in this study. Pelvic tilt (dominant side) was measured from a digital photo with clear reflector markers on the anterior superior iliac spine (ASIS) and posterior superior iliac spine (PSIS) using the Kinovea video analysis software programme (version 0.8.15). Flexibility of the hamstrings, hip flexors and knee extensors was assessed with goniometry. Core stability was assessed using the pressure biofeedback unit and muscle onset times during the ascent phase of non-weighted squats. The onset times of the transverse abdominis (TrA), erector spinae (ES), gluteus maximus (GM) and biceps femoris (BF) muscles were measured using electromyography (EMG). Players were then grouped according to pelvic tilt (anterior and neutral) and by playing position (forwards and backs). The between group differences were evaluated for the abovementioned variables using p-value (statistical significance) and d-value (practical significance) measures. Muscle activation patterns and firing order were determined using descriptive statistics. The mean pelvic tilt of all participants (N=49) was an anterior tilt of 15.35°. When grouped by pelvic tilt, the anterior tilt group showed a mean pelvic tilt of 17.83° (n=27) and the neutral pelvic tilt group showed a mean pelvic tilt of 11.75° (n=22). Despite the differences in pelvic tilt, there was no significant difference in flexibility between the groups. Another controversial result is that the anterior tilt group showed practical significantly better core stability (d=0.54) than the neutral tilt group (46.93° vs 56.3°). During the double leg squat the muscle activation patterns were consistent between the groups. TrA activated first, followed by ES. Thereafter, the BF muscle activated, followed by the GM. The first place activation of TrA is consistent with the literature stating that the deep abdominal stabilisers of individuals with good core stability activate before the movement is initiated. The early onset of muscle activity of ES points to a focus on back extension during the ascent of the squat. Because the pelvic tilt was measured during static standing only, it is unclear whether the players in the neutral tilt group were able to hold the neutral pelvic tilt posture throughout the movement. Research has shown that there is an increased focus on trunk extension during the ascent phase of the squat which is not present during the descent. Future research should focus on assessing the pelvic tilt at the beginning of the ascent phase of the squat to ensure accurate results. The delay in GM activation during the ascent of the squat is concerning. GM acts as a lumbopelvic stabilizer, and its slow activation points to a decrease in lumbopelvic stability. This is very important in weight training, because weight training increases the strain on the lumbar spinal structures, which decreases performance and increases the risk of injury. / MSc (Biokinetics), North-West University, Potchefstroom Campus, 2014

Hamstring injuries have a high prevalence in rugby union players. Delayed transverse abdominus activation as well as lordosis is associated with hamstring injuries. No literature regarding this relationship in rugby players could have been found. The main purpose of this study was therefore to determine the relationship between pelvic biomechanics (transverse abdominus activation and pelvis tilt) and gluteus maximus, hamstring and erector spinae activation patterns in semi–professional rugby union players as well as the relationship of the above mentioned variables and hamstring injuries. A total of 65 players voluntarily participated in this study. Pelvis tilt (left and right) was assessed by Dartfish version 4.06.0 (Dartfish, Switzerland). Transverse abdominus activation (TrA) was assessed by pressure biofeedback and the mean onset times of the left and right gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST) and lumbar erector spinae (LES) was measured with electromyography (EMG). In order to determine the role of the pelvic biomechanics and activation patterns on hamstring injuries, players were retrospectively grouped in injured and uninjured groups. Differences between the groups were determined with regards to the variables determined. Activation patterns were determined by means of descriptive statistics. The between–group pelvic biomechanic (pelvic tilt and TrA) differences in the muscle (GM, LES and hamstrings) onset times were analysed by determining practical significance by means of effect sizes. An anterior pelvic tilt on the left side was observed in 64.6% of the participants and on the right side in 83.1% of the participants. TrA testing indicated that 68.4% of participants were classified with bad activation and 31.6% with good activation. No practical significant difference was found in the mean onset times of each muscle relative to the other in the normal and anterior tilted pelvis groups as well as in the bad and good TrA groups. A total of 24.6% of the rugby players previously suffered from hamstring injuries, 37.5% of those injured participants were suffering from re–injury. No practical significant between group differences were found when the injured and uninjured groups were compared with regards to anterior pelvis tilt values (d=0.061) and TrA values (d=0.189). EMG results on the right and left side of the injured and uninjured participants present a pattern of the following activation order: LES, GM, BF and lastly ST. No practical significant between groups differences were found in the onset times of the muscles relative to each other in the injured compared to uninjured groups. The conclusions that can be drawn from this study is that semi–professional rugby union players (injured and uninjured) are prone to postural defects such as anterior tilt of the pelvis and bad TrA. Anterior pelvic tilt and bad TrA may be the reason for the earlier activation of the LES and hamstrings muscles relative to the GM in the prone hip extension to stabilize the lumbar spine. These activation patterns were however not influenced by previous hamstring injuries. / Thesis (M.A. (Biokinetics))--North-West University, Potchefstroom Campus, 2011.

Hamstring injuries have a high prevalence in rugby union players. Delayed transverse abdominus activation as well as lordosis is associated with hamstring injuries. No literature regarding this relationship in rugby players could have been found. The main purpose of this study was therefore to determine the relationship between pelvic biomechanics (transverse abdominus activation and pelvis tilt) and gluteus maximus, hamstring and erector spinae activation patterns in semi–professional rugby union players as well as the relationship of the above mentioned variables and hamstring injuries. A total of 65 players voluntarily participated in this study. Pelvis tilt (left and right) was assessed by Dartfish version 4.06.0 (Dartfish, Switzerland). Transverse abdominus activation (TrA) was assessed by pressure biofeedback and the mean onset times of the left and right gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST) and lumbar erector spinae (LES) was measured with electromyography (EMG). In order to determine the role of the pelvic biomechanics and activation patterns on hamstring injuries, players were retrospectively grouped in injured and uninjured groups. Differences between the groups were determined with regards to the variables determined. Activation patterns were determined by means of descriptive statistics. The between–group pelvic biomechanic (pelvic tilt and TrA) differences in the muscle (GM, LES and hamstrings) onset times were analysed by determining practical significance by means of effect sizes. An anterior pelvic tilt on the left side was observed in 64.6% of the participants and on the right side in 83.1% of the participants. TrA testing indicated that 68.4% of participants were classified with bad activation and 31.6% with good activation. No practical significant difference was found in the mean onset times of each muscle relative to the other in the normal and anterior tilted pelvis groups as well as in the bad and good TrA groups. A total of 24.6% of the rugby players previously suffered from hamstring injuries, 37.5% of those injured participants were suffering from re–injury. No practical significant between group differences were found when the injured and uninjured groups were compared with regards to anterior pelvis tilt values (d=0.061) and TrA values (d=0.189). EMG results on the right and left side of the injured and uninjured participants present a pattern of the following activation order: LES, GM, BF and lastly ST. No practical significant between groups differences were found in the onset times of the muscles relative to each other in the injured compared to uninjured groups. The conclusions that can be drawn from this study is that semi–professional rugby union players (injured and uninjured) are prone to postural defects such as anterior tilt of the pelvis and bad TrA. Anterior pelvic tilt and bad TrA may be the reason for the earlier activation of the LES and hamstrings muscles relative to the GM in the prone hip extension to stabilize the lumbar spine. These activation patterns were however not influenced by previous hamstring injuries. / Thesis (M.A. (Biokinetics))--North-West University, Potchefstroom Campus, 2011.