In the current study, we adopted the hypothesis that the body scheme disturbances occurring during adolescence might lead subjects to transiently neglect proprioceptive information and that adolescents might rely more strongly on vision to control their orientation and stabilize their body. To check this point, we asked adolescents 14–15 years to maintain vertical stance while very slow sinusoidal oscillations in the frontal plane were applied to the supporting platform at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above) with the eyes open and closed. Two postural components, orientation and segmental stabilization, were analyzed at the head, shoulder, trunk, and pelvis levels. At the lowest frequency without vision, the performances of adolescents were much less efficient than those of adults. Moreover, this study showed that vision plays a predominant role in adolescents’ control of orientation and body stabilization. At 0.06 Hz without vision, a clearcut difference was observed between the strategies used by girls and boys; specifically, the maturation of the segmental stabilization processes was found to be more advanced in girls than in boys. However, no such difference was observed at 0.01 Hz. Lastly, comparisons between the data obtained in adolescents and those previously obtained in young adults (Vaugoyeau, Viel, Amblard, Azulay, & Assaiante, 2008) clearly show that adolescents use different postural strategies and that they are not yet capable of reaching comparable postural performance levels to those observed in adults. Because adolescents were not able to use the proprioceptive information available to improve their postural control, we concluded that they showed a maturational lag in comparison with adults. This suggests that the mechanisms underlying postural control are still maturing during adolescence, which might constitute a transient period of proprioceptive neglect in sensory integration of postural control.
Sébastien Viel, Marianne Vaugoyeau and Christine Assaiante
Niels J. Nedergaard, Mark A. Robinson, Elena Eusterwiemann, Barry Drust, Paulo J. Lisboa and Jos Vanrenterghem
To investigate the relationship between whole-body accelerations and body-worn accelerometry during team-sport movements.
Twenty male team-sport players performed forward running and anticipated 45° and 90° side-cuts at approach speeds of 2, 3, 4, and 5 m/s. Whole-body center-of-mass (CoM) accelerations were determined from ground-reaction forces collected from 1 foot–ground contact, and segmental accelerations were measured from a commercial GPS accelerometer unit on the upper trunk. Three higher-specification accelerometers were also positioned on the GPS unit, the dorsal aspect of the pelvis, and the shaft of the tibia. Associations between mechanical load variables (peak acceleration, loading rate, and impulse) calculated from both CoM accelerations and segmental accelerations were explored using regression analysis. In addition, 1-dimensional statistical parametric mapping (SPM) was used to explore the relationships between peak segmental accelerations and CoM-acceleration profiles during the whole foot–ground contact.
A weak relationship was observed for the investigated mechanical load variables regardless of accelerometer location and task (R 2 values across accelerometer locations and tasks: peak acceleration .08–.55, loading rate .27–.59, and impulse .02–.59). Segmental accelerations generally overestimated whole-body mechanical load. SPM analysis showed that peak segmental accelerations were mostly related to CoM accelerations during the first 40–50% of contact phase.
While body-worn accelerometry correlates to whole-body loading in team-sport movements and can reveal useful estimates concerning loading, these correlations are not strong. Body-worn accelerometry should therefore be used with caution to monitor whole-body mechanical loading in the field.
Rafael F. Escamilla, Glenn S. Fleisig, Coop DeRenne, Marcus K. Taylor, Claude T. Moorman III, Rodney Imamura, Edward Barakatt and James R. Andrews
We propose that learning proper hitting kinematics should be encouraged at a young age during youth baseball because this may help reinforce proper hitting kinematics as a player progresses to higher levels of baseball in their adult years. To enhance our understanding between youth and adult baseball hitting, kinematic and temporal analyses of baseball hitting were evaluated with a high-speed motion analysis system between 12 skilled youth and 12 skilled adult baseball players. There were only a small number of temporal differences between youth and adult hitters, with adult hitters taking significantly greater time than youth hitters during the stride phase and during the swing. Compared with youth hitters, adult hitters a) had significantly greater (p < .01) lead knee flexion when the hands started to move forward; b) flexed the lead knee over a greater range of motion during the transition phase (31° versus 13°); c) extended the lead knee over a greater range of motion during the bat acceleration phase (59° versus 32°); d) maintained a more open pelvis position at lead foot off ground; and e) maintained a more open upper torso position when the hands started to move forward and a more closed upper torso position at bat-ball contact. Moreover, adult hitters had greater peak upper torso angular velocity (857°/s versus 717°/s), peak left elbow extension angular velocity (752°/s versus 598°/s), peak left knee extension angular velocity (386°/s versus 303°/s), and bat linear velocity at bat-ball contact (30 m/s versus 25 m/s). The numerous differences in kinematic and temporal parameters between youth and adult hitters suggest that hitting mechanics are different between these two groups.
Noah X. Tocci, David R. Howell, Dai Sugimoto, Corey Dawkins, Amy Whited and Donald Bae
-related injury. 9 , 11 , 18 Lower extremity movement, in particular pelvis movement, is one fundamental aspect to proper pitching mechanics. 9 , 19 , 20 Specifically, the pelvis acts as the foundation to the throwing motion, and serves an integral role in the transfer of energy during a pitch. 21
Nicole C. George, Charles Kahelin, Timothy A. Burkhart and David M. Andrews
anatomical landmarks Measurements Segment Description and landmarks Lengths Pelvis (A) Vertical distance between the pubic symphysis and the level of the most prominent ridge on the superior aspect of the iliac crest Pelvis (L) ‡ Vertical distance between the
Erin Macaronas, Shannon David and Nicole German
or effusion”, and “chronic expanding hematoma.” 1 Morel-Lavallée lesions are most commonly a result of severe trauma occurring at the greater trochanter and other parts of the pelvis. 1 – 3 Although the greater trochanter is the most common location for Morel-Lavallée lesions to occur, cases of the
Hae-rim Han, Chung-hwi Yi, Sung-hyun You, Heon-seock Cynn, One-bin Lim and Jae-ik Son
Biomechanically, the gluteus medius (GMED) controls femoral motion during dynamic lower-extremity motion, and counteracts gravity to stabilize the pelvis in a single-leg stance. 1 , 2 However, when the GMED becomes weak, numerous neuromuscular problems including hip joint pathology, lateral hip
Alyssa C. Adams, Kelly B. Fleming and Patricia M. Tripp
athletic training staff with pain in her left hip at the beginning of competition season. She reported no previous history of hip, groin, or pelvis pathology, but did have a history of a pars fracture at L2 and L5 and a herniated disc at T12. Her chief complaint was left hip pain initially originating
Osamu Yanagisawa, Kenta Wakamatsu and Hidenori Taniguchi
The importance of lower-extremity function in baseball pitching is well recognized. In particular, the concern with hip function of baseball pitchers has been growing recently. The hip function is involved in the motion and stability of the pelvis, weight shift from a pivot leg (leg on the same
Christian A. Clermont, Sean T. Osis, Angkoon Phinyomark and Reed Ferber
recreational runners according to differences in gait kinematics at the ankle, knee, and hip joints as well as the foot and pelvis segments in all 3 planes of motion. We hypothesized that we could separate and classify competitive and recreational runners and that the projected differences between groups would