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Article Excerpt
Key words: self-determination theory, validity
Recent research (Mullen & Markland, 1997) and commentary (Vallerand & Fortier, 1998) suggests there has been a surge of interest in understanding exercise motivation from the perspective of Self-Determination Theory (SDT; Deci & Ryan, 1985). According to SDT, social contexts that facilitate the satisfaction of competence, autonomy, and relatedness needs underpin the development of more self-determined motives. These motives have subsequently been linked with greater behavioral persistence and more positive psychological functioning in both sport and exercise contexts (for a review, see Vallerand & Fortier, 1998).
An important aspect in the study of these theoretical relationships has been the need to develop psychometrically sound instruments that adequately measure the constructs embedded within SDT. One instrument developed for this purpose is the Motivation for Physical Activity Measure (MPAM; Frederick & Ryan, 1993), which was designed to assess multiple motives for physical activity participation. In this regard, competence, enjoyment, and body relations were deemed representative of intrinsic and extrinsic motives prevalent in the physical domain. Ryan and colleagues (Ryan, Frederick, Lepes, Rubio, & Sheldon, 1997) later revised the MPAM (forming the MPAM-R) by adding both social and health-fitness subscales, because these motives were thought to be relevant to potential reasons for exercise participation. The MPAM-R was validated on the basis of responses from new registrants at a university fitness facility (N = 155; M age = 19.3 years, SD = 3.0; 57.4% were women). The final version of the MPAM-R assesses five motives for engaging in physical activity that are underpinned by varying degrees of psychological need satisfaction from low (appearance) to high (social, competence-challenge, fitnesshealth, and interest-enjoyment).
Although the MPAM-R has some appeal for research addressing motivational issues from a SDT perspective, it is surprising that relatively little research has attempted to establish the construct validity of this measure. Currently, the evidence associated with the MPAM-R's construct validity is confined to a single study using exploratory factor analytic (CFA) procedures (Ryan etal., 1997) and examining the ability of the MPAM-R to predict exercise adherence. Given that measurement experts have presented a cogent argument favoring the ongoing assessment of a scale's merit (Messick, 1995), there appears to be a need to expand the evidence pertaining to the validity of the MPAM-R before addressing the central postulates of SDT using this instrument.
The purpose of this study was to examine the construct validity of the MPAM-R in physically active women by: (a) testing the factor structure using CFA procedures, and (b) examining the relationships between the MPAM-R subscales and the psychological need satisfaction constructs proposed within SDT. Active women were examined in this study, because recent health reports indicate that women are significantly less active than men (Craig, Russell, Cameron, & Beaulieu, 1999), suggesting a need to further our understanding of the motives regulating women's physical activity participation. To address these purposes, we formulated hypotheses based on arguments embedded within SDT (Deci & Ryan, 1985) and Messick's (1995) contention that to be considered valid scales developed on theoretical grounds should demonstrate meaningful relationships with key theoretical constructs. Consequently, we hypothesized that: (a) the factor structure and composition of the MPAM-R would be consistent with the major tenets of SDT, and (b) competence, autonomy, and relatedness would exhibit stronger relationships with more self-determined motives (competence-challenge, enjoyment-interest, health-fitness, social) than less self-determined motives (appearance).
Method
Participants
Participants (N = 321) in this study were female students and staff enrolled in exercise classes (n = 20) at a large Canadian university. Study participants ranged in age from 18 to 74 years (M = 26.9 years; SD = 11.1) (1) and reported body mass index (BMI) values indicative of adequate health for this age cohort (M = 23.1 kg/m (2); SD = 5.4). Participants were enrolled in group-based exercise classes that met twice per week under the leadership of a qualified exercise instructor. Each class lasted for 55 min and was conducted at a moderate-to-strenuous intensity level recently advocated...
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