This study examined the relationships among eating attitudes, exercise identity, and body alienation in ultramarathoners. Eighty-seven competitive ultramarathoners (73 males, 14 females) completed the Eating Attitudes Test–26, Exercise Identity Scale, and Body Alienation Scale as part of their pre-race registration. Correlation coefficients revealed that eating attitudes were positively related to exercise identity (R = 0.31) and injury tolerance (R = 0.43), and that exercise identity was positively related to injury tolerance (R = 0.33). MANOVA further indicated that subjects with high exercise identity reported more eating disorder behaviors [F(2, 80) = 7.73, P < 0.001 J and higher injury tolerance [F (2, 80) = 3.69, P < 0.05] than persons with low exercise identity. Female ultramarathoners scoring high on exercise identity were more likely to report aberrant eating behaviors [F (2, 80) = 3.39, P < 0.05J and higher training intensity levels [F (2, 80) = 3.91, p < 0.02J than were average males and the low- or moderate-exercise identifying females.
Christopher D. Lantz, Deborah J. Rhea and Karin Mesnier
The extrapolation of biological damage from a biomechanical model requires that a closed-form mathematical damage threshold function (DTF) be included in the model. A DTF typically includes a generic load variable, being the critical load (e.g., pressure, strain, temperature) causing irreversible tissue or cell damage, and a generic time variable, which represents the exposure to the load (e.g., duration, strain rate). Despite the central role that DTFs play in biomechanical studies, there is no coherent literature on how to formulate a DTF, excluding the field of heat-induced damage studies. This technical note describes six mathematical function types (Richards, Boltzmann, Morgan-Mercer-Flodin, Gompertz, Weibull, Bertalanffy) that are suitable for formulating a wide range of DTFs. These functions were adapted from the theory of restricted growth, and were fitted herein to describe biomechanical damage phenomena. Relevant properties of each adapted function type were extracted to allow efficient fitting of its parameters to empirical biomechanical data, and some practical examples are provided.
Klaus Schneider and Ronald F. Zernicke
With a validated mathematical model of the head-neck consisting of nine rigid bodies (skull, seven cervical vertebrae, and torso), we simulated head impacts to estimate the injury risk associated with soccer heading. Experimental data from head-linear accelerations during soccer heading were used to validate the nine-body head-neck model for short duration impact loading of the head. In the computer simulations, the mass ratios between head mass and impacting body mass, the velocity of the impacting body, and the impact elasticity were varied. Head-linear and angular accelerations were compared to standard head-injury tolerance levels, and the injury risk specifically related to soccer heading was estimated. Based on our choice of tolerance levels in general, our simulations showed that injury risk from angular head accelerations was greater than from linear head accelerations, and compared to frontal impacts, lateral impacts had greater angular and less linear head accelerations. During soccer heading, our simulations indicated an unacceptable injury risk caused by angular head accelerations for frontal and lateral impacts at relatively low impact velocities for children, and at medium range impact velocities for adults. For linear head accelerations, injury risk existed for frontal and lateral impacts at medium range to relatively larger impact velocities for children, while no injury risk was shown for adults throughout the entire velocity range. For injury prevention, we suggest that head-injury risk can be reduced most substantially by increasing the mass ratio between head and impacting body. In soccer with children, the mass of the impacting body has to be adjusted to the reduced head mass of a child, that is, it must be clearly communicated to parents, coaches, and youngsters to only use smaller soccer balls.
Theresa L. Miyashita and Paul A. Ullucci
central server. We evaluated the following information provided by the GFT: linear acceleration, head injury criteria (HICs), Gadd severity index scores, maximum rotational acceleration, and total number of impacts. HIC and Gadd severity index scores are injury tolerance scores and take into consideration