The influence of task constraints on the glenohumeral horizontal abduction angle of the overarm throw of novice throwers.

The action of the throwing arm during the development of the mature overarm throwing pattern has garnered much attention in recent years. Many of these studies have incorporated Newell’s (1986) developmental model into the description of the organismic (e.g., Halverson, Roberton, & Langendorfer, 1982; Langendorfer & Roberton, 2002) and/or environmental constraints placed upon the thrower (e.g., Thomas & French, 1985; Thomas, Michael, & Gallagher, 1994). According to Newell, three types of constraints—the organism, environment, and task—must be considered when investigating factors related to motor development and learning. These factors and their interactions are included in Newell’s triangular model as key sources of constraint when examining motor development at any age. Constraints are usually defined as facilitative channeling of movement, or limitations thereof, implying that constraints either encourage or limit motor development depending on the characteristics of the constraints (Haywood & Getchell, 2005). Organismic constraints involve the genetic makeup and an individual’s unique characteristics, such as height, limb length and mass, attentional focus, motivation, and arousal level. Because of organismic constraints, people performing the same task in identical environments may achieve various degrees of success (Haywood & Getchell, 2005). Environmental constraints include those that describe the setting in which an organism lives and thrives. For example, light, temperature, humidity level, air quality, nutritional opportunities, laws, cultural beliefs and practices, and normative views regarding acceptable behavior represent environmental constraints (Haywood & Getchell). Task constraints are controls that are placed upon the execution of the skill, such as skill criteria, equipment used, and the task itself (Haywood & Getchell). Only a few studies have accounted for the third axiom of Newell’s model, which is the task constraint (Cross, 2004; Southard, 1998). For instance, several studies have investigated how various populations of children respond to different instructional strategies when learning the skill of throwing (e.g., Goodway & Branta, 2003; Goodway, Rudisill, & Valentini, 2002; Valentini & Rudisill, 2004a, 2004b), but the majority of the studies have not reported or described the size or weight of the throwing implement. The failure to report and/or standardize task constraints, such as ball size and weight, makes comparisons across studies difficult, due to evidence that the size and weight of the ball influence the mechanics of overarm throwing (Alexander, 1991; Cross; 2004). Therefore, this study aimed to determine the influence of task constraints on the horizontal abduction angle of the overarm throw of novice throwers. Specifically, the study attempted to determine whether increasing the inertial components of the distal portion of the throwing arm forces the arm into an increased glenohumeral horizontal abduction angle. In an attempt to define the effects of task constraints on the overarm throwing motion, Alexander suggested The Influence of Task Constraints on the Glenohumeral Horizontal Abduction Angle of the Overarm Throw of Novice Throwers