Effect Of a Training Program On Landing Kinematics And Kinetics In Children With Developmental Coordination Disorder

Introduction
To land safely, a child predicts the time and external forces (3) of landing and produces appropriate lower limb eccentric
muscle contractions that slow the body’s momentum and cushion the body from potentially damaging ground impact
force. However, the issue of how well children with developmental coordination disorder (DCD), cushion their
landings, is of great importance. Children with DCD are described by the American Psychiatric Association as having
motor coordination difficulties that interfere with performance of daily motor activities (1). However, techniques used
by children with DCD during landing are rarely described (2). A more complete picture of the landing patterns of
children with different levels of coordination may contribute to the development of training methods, remediation and
injury prevention, in this population. So, the purpose of the study was twofold a) to investigate the landing kinematic
and kinetic characteristics in children aged 7-9 years old, with DCD, or without coordination problems (NC) and b) to
study the effect of a specifically designed training program on these biomechanical characteristics.

Methods
9 DCD (B. Weight = 37.2 ± 6.3 Kg, B. Height = 141.2± 2.2 cm) and 9 NC children (B. Weight = 35.8 ± 7.9 Kg, B.
Height =141.2± 7.8 cm) served as experimental groups, participating in a 12-week training program 2 sessions per
week, which consisted of modified games and activities based on basketball skills. Moreover, 9 NC (B. Weight = 39.7
± 3.7 Kg, B. Height =143.4 ± 4.9 cm) children served as controls. DCD children were identified by Μovement
Assessment Battery for Children (Movement ABC, Henderson & Sugden, 1992). All groups videotaped with a videocamera
Panasonic PV-900 (1-D analysis), 60 Hz, performing two-foot landings from a height of 20cm, onto a force
platform (Kistler, Type 9281CA), sampling at 1000Hz. Tests were performed pre and post the application of the training
program. Performance variables were the following: The first impact peak force normalized to bodyweight
(RFz1 = Fz1/BW), the maximum loading peak vertical ground reaction force normalized to bodyweight (RFz2 =
Fz2/BW), the time from touchdown to F2 (TFz2) and the landing time (LT), time from touchdown to minimum hip height
were obtained from the force plate output. The ankle, knee and hip joint range of motion (AROM, KROM and HROM
respectively) were derived from the video data.

Results
One-way analysis of variance (ANOVA) was applied to the pre training variables. Results showed that there was a
statistical significant effect of the group on the following variables, RFz2 (F (2,26) = 7.7), LT(F (2,26) = 2.9), AROM (F (2,26)
= 5.5) and KROM (F (2,26) = 3.6), p< 0.05. Moreover, repeated measures design for kinetic and kinematic variables
showed statistical significant differences for RFz1 (F(1,24) = 5.7), RFz2 (F(1,24) = 7.2), LT(F(1,24) = 5.5), AROM (F(1,24) =
23.9), KROM (F(1,24) = 5.9), for p < 0.05, pre and post training. Additionally, statistical significant interactions were
reported for RFz2 (F(2,24) = 10.4) and AROM (F(2,24) = 3.4), p< 0.05 variables. Descriptive statistics for kinetic and
kinematic variables are depicted on table 1

Discussion / Conclusion
Results showed evidence that, children with DCD performed less safe landings, which was characterized by high
vertical ground reaction force, short landing time, smaller angle and knee range of motion, compared to their NC peers.
In addition, the basketball skills training program seemed to have improved performance in DCD children, regarding
ground reaction forces and landing time. Results are discussed according to results derived from previous studies [2].
In conclusion, there are important implications for both coaches and teachers of young children, because, although
landing seems to be a simple skill, which is learned quickly and naturally, it requires extensive and thorough teaching.
This is especially important for children with DCD, in order to safely participate in sport and physical activities.

References
[1] American Psychiatric Association (1994). Washington, DC: American Psychiatric Association.
[2] Larkin, D. & Parker, H.E. (1998). Pediatric Exercise Science, 10, 123-136.
[3] McKinley, P., & Pelland, L. (1994). In E., Fredrizzi, G., Avanzini, & P., Crenna (Eds.) Motor Development in
Children (pp. 71-78). London: John Libbey.

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