As noted by David Williams and his colleagues , prevalence rates for physical activity remain disappointingly low, especially given how much attention has gone into research efforts to increase both adoption and adherence of physical
activity behaviors. Their most recent effort provides a nice replication/extension of their earlier work  which showed that affect experienced during an acute bout of aerobic exercise predicted physical activity participation 6 and 12 months later. Specifically, that study found that a 1-unit increase in affect [via the feeling scale (FS); 3] during moderate-intensity exercise was associated with 38 min of additional physical activity 6 months later and 41 min of extra physical activity 12 months later. Essentially, the current study shows the same pattern, with affect experienced during a 10-min treadmill walk associated with increased physical activity 6 and 12 months later (29 and 14 min, respectively). There are several points related to this work that I am compelled to mention, some critical and some suggestive, but all are meant in the spirit of further increasing our ability to get people to not only start moving, but to keep them moving.
First, it is rather gratifying to see more and more work heeding the call of Ekkekakis and Petruzzello  for examination of affect experienced during exercise in addition to the historical paradigm of comparing pre- to post-exercise changes. Williams et al. are not the first to have done this [see 5], but rather this methodological feature is clearly providing insights that weren’t garnered before. Indeed, in the current study ofWilliams et al., post-walk affective responses were not predictive of future exercise behavior—it was only the affect experienced during the walk that was able to provide such predictions. Without a shift in the exercise–affect paradigm, these insights would have remained hidden.
Admittedly, examination of in-task affect was not necessarily a novel idea. For example, Emmons and Diener  showed that time spent in an activity was influenced by the affect experienced during the activity. It would seem straightforward to ask whether what a person feels during physical activity has any influence on their choice to continue to engage in future physical activity. As my colleague Panteleimon Ekkekakis puts it: “Common sense and the socalled ‘hedonic’ theory of motivation would suggest that, if people derive pleasure, a sense of energy or enjoyment, they would probably seek to repeat this activity. On the other hand, if they derive displeasure, discomfort, pain, or a sense of exhaustion, the chances of them repeating the activity or adhering to it over the long run would be diminished” [7, p. 858; see also 8]. While not definitive, the current study shows that what an individual feels during a brief bout of exercise is predictive of their future involvement with regular physical activity. These results offer further support to our claim that affective responses can provide motivation for physical activity: “One feature of exercise that has been identified as having potential motivational significance is the affective response (e.g., pleasure or displeasure, tension or relaxation, energy or tiredness) that exercisers experience” [5, p. 643].
It is also worth pointing out that the results might be fairly conservative. The results of Williams et al. indicated fairly modest relationships between in-task affect and physical activity at 6 and 12 months rs00.16–0.36). It would be interesting to see what would happen to such relationships if the participant is allowed to choose their own intensity during the treadmill task rather than having it imposed by the investigators. The participant was allowed some freedom to modify their walking speed (i.e., intensity), but only if it remained within a prescribed range. Thus, while the intensity was “self-selected,” it would be interesting to see if a less prescribed intensity range would have resulted in selection of higher intensities and stronger relationships with future physical activity. This would be consistent with the evidence that participants tend to self-select higher intensities and/or they tolerate (i.e., feel more pleasant) intensities at lower levels when they are prescribed [7, p. 872].
In spite of the generally positive findings from this study, there are several questions that remain regarding the change in physical activity behavior. Admittedly, the assessment of affect in conjunction with acute exercise at various times during the individually tailored physical activity promotion intervention was a secondary objective of a larger project [see 9]. However, the effectiveness of that intervention appears rather modest. Granted that participants increased their physical activity from approximately 13 min per week−1 at baseline to 125 and 95 min per week−1 at 6 and 12 months, but in reporting the median level of physical activity at 6 and 12 months (with no variability being reported), it is difficult to discern how broadly effective this was. Even with this, it is disheartening that at best, weekly physical activity was still less than the national recommendations of at least 150 min per week−1 and that it got worse over the second 6-month period.
It might also be insightful to have assessments of affect at the baseline measurement period. The authors address this by noting their concern that drawing attention, via the FS, to the possible aversiveness of the initial 10-min treadmill walk might have decreased participant motivation. This concern seems to imply that the same motivational influence wasn’t present by asking participants to rate their perceptions of exertion during the initial treadmill walk. Clearly, affect and perceptions of exertion are not the same [see 3], but drawing attention to how hard one is working might be just as negatively influential on motivation as drawing attention to one’s affective state. Thus, it would seem fruitful to include both assessments in the future.
As a final point of emphasis for future research, it would be instructive to examine changes in affective responses at the individual level in addition to the group level. This is even more salient for the current study, given the nature of the tailored physical activity intervention. “From a practical standpoint, if the factors that contribute to variability in affective responses are identified, this could spur the development of individually tailored interventions, thus optimizing the exercise experience” [5, p. 657]. Whereas it appeared that the intervention did include some aspects of enjoyment, the Williams group has shown in previous work that enjoyment can moderate the effects of a physical activity intervention . Further, it is quite likely that not all participants in the current study experienced increases in affect during the 10-min treadmill walk. Examination of this variation could be instructive in further tailoring the intervention. For example, experiencing a decline in affect might not only reflect an aversion to the exercise, but could reflect unhappiness with the lack of challenge presented by the task. Clearly the tailoring of the exercise prescription would be different in these two instances. It is likely that the affective responses were largely homogeneous (i.e., primarily increased affect), but these kinds of responses should be examined both at the group and individual levels.
The study by Williams and colleagues is a nice extension of their previous work with a considerably larger sample of participants. As they noted, even modest increases in weekly physical activity could have fairly profound implications for public health. Greater attention to in-task affective responses, individual variations in those responses, and assessment of baseline affective responses would all seem important factors for consideration in future research of this type. It would also be interesting to examine the effectiveness of an exercise intervention that focused more attention on the affective factors of physical activity and exercise rather than the traditionally exclusive focus on social–cognitive factors. Such a change in focus will necessarily entail greater attention to exercise intensity given the growing evidence documenting this link, but selfmonitoring and self-regulation may provide the keys to increasing exercise adherence .
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