Momentary assessment of affect, physical feeling states, and physical activity in children.

Despite accumulating evidence of the health benefits of regular physical activity (Strong et al., 2005), most children in the U.S. are physically inactive. Recent estimates suggest that only 40–50% of children 6–11 years of age and 6–11% of children 12–15 years of age engage in ≥60 minutes per day of moderate-intensity activity on at least 5 out of the past 7 days (Troiano et al., 2008). In order to address this problem, correlational and experimental studies have sought to identify cognitive, social, and environmental factors associated with physical activity among children (Ferreira et al., 2007; Van der Horst, Paw, Twisk, & Van Mechelen, 2007). However, the impact of these variables on physical activity has been limited, and many of the observed effects are modest in magnitude (Van Sluijs, McMinn, & Griffin, 2008). Thus, it may be fruitful to identify other psychosocial factors that play a role in physical activity among children. There is growing interest in understanding the complex interrelationships between emotions, subjective physical feeling states (e.g., energetic arousal, fatigue), and physical activity in children. For instance, children who are more physically active tend to have lower levels of depressive symptoms (McDermott et al., 1990), and engaging in structured physical activity has been shown to reduce depression (Norris, Carroll, & Cochrane, 1992). Likewise, children report enhanced positive affect and feeling physically energetic, and reduced negative affect after structured exercise tasks (Schneider, Dunn, & Cooper, 2009). Plausible mechanisms underlying a beneficial affective response to physical activity include mood enhancement through biological pathways (e.g., beta-endorphins, endogenous opioids) (Dinas, Koutedakis, & Flouris, 2011; Grossman et al., 1984) and psychological processes (e.g., increased sense of achievement, self-esteem, self-efficacy) (Scully, Kremer, Meade, Graham, & Dudgeon, 1998). Although these studies offer support for the effects of habitual and acute exercise on affective and physical feeling states, the question of whether affective and physical feeling states impact children’s decisions to engage in physical activity remains unanswered. Emotional states are thought to play a central role in motivational processes underlying a variety of behaviors (Naqvi, Shiv, & Bechara, 2006), including those that promote physical health such as physical activity. For example, positive emotional states may influence health-relevant behaviors by engendering psychological resources (e.g., coping, social support) (Salovey, Detweiler, & Steward, 2000) or increasing appetitive motivation to participate in those behaviors (Updegraff, Gable, & Taylor, 2004). In contrast, negative emotions may trigger a motivational state of behavioral avoidance (Leone, Perugini, & Bagozzi, 2005), which could extend to multiple effortful behaviors, including physical activity. Thus, there may be a bi-directional association between affective states and physical activity. However, methodological weaknesses of past studies have restricted the capacity to test the effects of affective states on naturally-occurring physical activity levels in children. A limitation of past research in this area is the reliance of structured exercise tasks in controlled laboratory settings to assess the association of exercise, affect, and physical feeling states. Participants are typically asked to perform a standardized exercise task such as riding stationary cycle or running on a treadmill for a specific intensity for a prescribed duration (Schneider et al., 2009). However, it has been shown that structured indoor physical activity causes greater perceived exertion (Bertucci, Grappe, & Groslamber, 2007) and is less psychologically restorative (Hug, Hartig, Hansmann, Seeland, & Hornung, 2009) than physical activity taking place in outdoor or naturalistic conditions. Thus, research is needed to understand how affective and physical feeling states may impact the choice to perform physical activity in free-living settings. Another limitation of past research is the lack of focus on within-person differences in affective and physical feeling states. There is growing evidence suggesting that children’s affective and physical feeling states can vary considerably across each day (Axelson et al 2003; Larson & Lampman-Petraitis, 1989). Also, the degree of within-person (i.e., intraindividual) variability in affect over time is related to important physical and psychological health outcomes (Dumitrescu, Dogaru, & Dogaru, 2008; Weinstein, Mermelstein, Shiffman, 2008). Cross-sectional studies or intervention studies with pre-post measurements designs cannot adequately capture intraindividual variability (i.e., the degree of instability) in affective and physical feeling states. These methodological weaknesses can be overcome with a real-time data capture strategy called Ecological Momentary Assessment (EMA). EMA obtains self-reports of psychological, affective, and behavioral variables during the course of everyday life (Bolger, Davis, & Rafaeli, 2003; Shiffman, Stone, & Hufford, 2008). In some modern EMA applications, mobile phones trigger the completion of brief electronic surveys through auditory signals programmed to occur at predetermined intervals throughout the day. Electronic surveys are time-stamped in order to be temporally linked to other types of data such as contemporaneous physical activity levels. Preliminary studies have used EMA to examine the associations of affective and physical feeling states with physical activity in adults (Dunton, Atienza, Castro, & King, 2009; Kanning, & Schlicht, 2010; Lepage, 2011; Schwerdtfeger et al., 2010; Wichers et al., 2012) and between affective states and other health behaviors such as smoking (Hedeker, Mermelstein, Berbaum, & Campbell, 2009) and caffeine consumption (Whalen et al., 2008) in children. Research has also used EMA to examine social and physical environmental influences on children’s physical activity (Dunton, Intille, Wolch, & Pentz, 2012; Dunton, Kawabata, Intille, Wolch, & Pentz, 2012; Dunton, Liao, Intille, Wolch, & Pentz, 2011). However, there is no published study capitalizing on EMA methodology to investigate linkages between affective and physical feelings states and physical activity in children. The current study used EMA to examine how affective and physical feeling states are related to objectively-measured physical activity in children ages 9 to 13 years. In previous analyses of this sample (Dunton et al., 2011; Dunton, Intille, et al., 2012; Dunton, Kawabata et al., 2012), we focused on non-affective correlates of physical activity. The current paper reflects a unique contribution by focusing specifically on the relation of affective and feeling states to physical activity and attempts to elucidate affective mechanisms of physical activity in children. The first objective was to determine whether affective and physical feeling ratings at any given EMA prompt predict subsequent moderate-to vigorous physical activity (MVPA) in the 30 minutes after the prompt. It was hypothesized that more positive affect/feeling energetic and less negative affect/feeling tired at any given EMA prompt (relative to the child’s own average level and other children) would predict more MVPA minutes measured in the 30 minutes following that EMA prompt. The second objective was to determine whether affective and physical feeling ratings at any given EMA prompt are predicted by MVPA in the 30 minutes before the prompt. We hypothesized that more MVPA minutes in the 30 minutes before any given EMA prompt (relative to the child’s own average level and other children) would predict more positive affect/feeling energetic and less negative affect/feeling tired at the time of that EMA prompt. The third objective was to determine whether across the entire monitoring period, individual differences in intraindividual variability (i.e., degree of instability) in affective and physical feeling ratings are associated with mean hourly leisure-time MVPA. We expected that children with lower leisure-time MVPA would show greater instability in affective and physical feeling states. Physical activity may stabilize mood and/or emotionally unstable children may lack psychological resources or executive cognitive capacities (Zelazo & Mueller, 2002) necessary for planning, organizing, and participating in regular physical activity regimens. We explored gender as a moderator for all of the objectives listed above.