Variability, or how a task changes across trials, may reveal differences between athletes of differing skill levels. The purpose of this study was to examine trunk and lower extremity (LE) single joint kinematic variability and intersegmental coordination variability in dancers and nondancers during bipedal vertical dance jumps (sautés). Twenty healthy females, 10 with no formal dance training and 10 professional dancers, performed 20 consecutive sautés. Single joint kinematic variability was assessed using mean standard deviation of angular displacement, and intersegmental coordination variability was assessed using angular deviation of the coupling angle between segments. Within the context of the standard error of measure, there was no difference in single joint kinematic variability between dancers and nondancers. Intersegmental coordination variability in the trunk was higher than variability in LE couplings for both groups. Dancers had lower intersegmental coordination variability than nondancers for LE sagittal, frontal, and transverse plane couplings, and sagittal plane trunk couplings. Trunk adjustments may be important for successful performance, but lower intersegmental coordination variability in expert dancers indicates a higher level of control. Trunk coordination and postural control may be important factors to investigate in skilled athletes.
Danielle N. Jarvis, Jo Armour Smith, and Kornelia Kulig
Hai-Jung Steffi Shih, Danielle N. Jarvis, Pamela Mikkelsen, and Kornelia Kulig
Bipedal tasks require interlimb coordination that improves with practice and acquisition of skills. The purpose of this study was to compare interlimb force coordination during dance-specific rate-controlled consecutive bipedal jumps (sautés) between expert dancers and nondancers. To analyze coordination of vertical ground reaction forces recorded under each leg, the vector coding approach was used. Although there were no differences in the patterns of interlimb force coordination between groups, the dancers exhibited less variability of interlimb force coordination during the transition phase from weight acceptance to propulsion as well as during the propulsion phase itself. The interlimb force coordination variability was associated with task performance only during the transition phase, which highlights the potential importance of control during this phase. In conclusion, expert dancers were better at reducing interlimb force coordination variability during the task-relevant transition phase, which was related to better performance at maintaining jump rate and jump height consistency.
Teri A. Todd, Keely Ahrold, Danielle N. Jarvis, and Melissa A. Mache
Children with autism spectrum disorder (ASD) typically demonstrate deficits in gross motor skills such as the overhand throw. It has not been determined whether such deficits persist into adulthood. Therefore, the purpose of this study was to examine the kinematics and developmental level of overhand throws among young adults with and without ASD. Three-dimensional motion-capture data were collected during overhand throwing trials performed by 20 college students (10 students with ASD). Individuals with ASD demonstrated similar throw duration, stride length, and step width but a longer acceleration phase and slower ball velocity than individuals without ASD. Young adults with ASD also performed the overhand throw with less developmental proficiency than those without ASD. Specifically, individuals with ASD exhibited developmental deficits in the backswing and composite throwing score. Motor skill interventions for individuals with ASD should address throwing skills, with a particular focus on the preparatory phase of the overhand throw.