A profile approach to physical activity levels: what’s intensity got to do with reasons and motives for exercise? | BMC Public Health
The findings from this expand on previous research examining physical activity (PA) intensity profiles by creating and analyzing five unique PA engagement patterns (clusters) based on intensity levels. These clusters allow for a deeper understanding of how different intensities of PA relate to adult motivation and exercise goals (e.g., reasons for exercise).
Physical activity cluster comparisons
The results comparing the PA profiles across adult’s exercise goals, which we refer to interchangeably as the reasons people have for exercising, supported significant and unique patterns. As hypothesized, the cluster analysis on PA categories was successful in creating unique profiles, with clusters differing on goals and behavior regulation subscales. Five unique PA clusters included the following: (1) a Sitting Profile – individuals in this cluster exhibited the highest levels of sedentary behavior; (2) a Low PA Profile – individuals in this cluster engaged in lower amounts of PA; (3) a Walking PA Profile – individuals in this cluster participated most in walking; (4) a Moderate Intensity PA Profile – individuals in this cluster engaged most in moderate PA; and (5) a High Intensity PA Profile – individuals in this cluster engaged most in vigorous PA It should be noted that the Low PA Profile does not indicate low levels of physical activity related to the U.S. Physical Activity Guidelines, rather the lower activity minutes with the exception of the sitting group, who also engaged in lower PA but was significantly more impacted with the highest reported levels of sitting behavior compared to the other profiles for the population included for this study.
PA profile differences
Our analysis revealed that individuals in the High Intensity and Moderate Intensity PA clusters reported greater endorsement (i.e., highest scores) of exercise reasons related to mood enhancement, solitude, social, fitness and competition compared to those in more sedentary clusters, such as the Sitting and Low PA profiles. These results highlight the potential motivaitonal differences driving engagement across PA intensity levels. As expected, indivdiuals engaging in more vigorous PA tended to have higher intrinsic motivaiton as shown in their higher Relative Autonomy Index (RAI) scors. These findings support theories like the Dual-Mode Theory, suggesting that intrinsic motivations (e.g., enjoyment, mastery) become more prominent at higher intensities. In contrast, less physically active individuals (Low PA, Sitting profiles) scored higher on controlling forms of motivation (e.g., weight management, appearance), which have been associated with less autonomy and potentially less sustained PA engagement.
More specifically, our findings highlight that exercisers that engage in higher-intensity or moderate-intensity type of PA also appear to value solitude, social, fitness, and competition as important reasons for exercising more than those who exhibit more time spent engaging in higher sedentary behaviors. The Low PA cluster had lower scores on solitude, social, fitness and competition than did the High Intensity PA cluster, suggesting exercisers that participate in more intense levels of PA value these reasons. Compared to the Walking PA cluster, the High Intensity PA cluster reported significantly higher scores in social reasons for exercising (M = 2.3 vs. 3.2) highlighting that relatedness may play a positive and supportive role in promoting engagement in PA at higher intensities than lower intensity form of PA, such as walking. High intensity functional training, as a group exercise modality, and similar to other sports and group exercise forms, has been shown to elicit intrinsic motivation (i.e., enjoyment, challenge), competition, and relatedness factors [7, 35, 36]. The notion that participants engaging in higher intensity forms of PA also exhibited higher scores in solitude compared to the low PA group may shed light to a less understood area of research where both solitude and group-fitness may co-exist in strength-training focused programs such as in high intensity functional training (e.g., barbell and strength training) [7, 35]. While these programs may be group-focused, it also tends to be autonomous forms of exercise where the participant is responsible for lifting their own/individual weight (i.e., independence) despite being in a social, group-focused program. Further research in this area would be beneficial and help understand how to encourage participation in higher intensity PA, in which strong supports highlights the cardiometabolic benefits from such engagement [12, 37, 38].
Interestingly, no significant differences were found across the five PA clusters for reasons such as weight management, appearance, or preventative health. These more extrinsic goals may represent societal pressures that are broadly internalized across different activity levels but may not necessarily translate into consistent or vigorous PA engagement, aligning with past findings that these goals can be controlling forms of motivation.
For instance, these findings are aligned with previous work highlighting that for participants who frequently reported weight loss and health benefit focused goals as most important also reported the least amount of PA engagement overtime compared to other goals because, of the reasons why people adopt these particular types of goals [8, 9, 18, 21, 39]. These goals are suggested to be a controlling form of motivation [5, 22, 24, 40], associated with lower perceived autonomy due to the pressure to conform to societal/social pressures. Weight loss goals, particularly for aesthetic purposes, are often considered a controlling form of motivation. In contrast, health benefit goals are generally associated with identified regulation, reflecting an internalized motivation unless driven by external pressures such as recommendations from family or healthcare providers. As a result, pressures associated with health, do not to promote self-worth, have high psychological costs, and result in decreased autonomous states, and thus seen to be as relatively weak goals that are not essential, and therefore identifying patterns in PA is difficult [5, 18, 27, 40]. Another observation based on the study finding that individuals who considered the goals ‘weight loss’ and ‘heath benefits’ most important also reported the least amount of PA engagement over time may suggest that distal outcomes like weight management and preventative health, although important, may not provide immediate satisfaction that motivates sustained vigorous PA. In contrast, with the exception of ‘fitness,’ many of the reasons to exercise that had the strongest correlations with vigorous PA were those where the satisfaction of the outcome was immediate to the activity. These include goals such as mood enhancement, solitude, social interaction, and competition (see Table 1). This pattern is consistent with elements of Hedonic Theory, which posits that behaviors providing immediate pleasure and satisfaction are more likely to be sustained [41]. Therefore, the immediate benefits experienced during PA, rather than long-term health outcomes, may play a more critical role in maintaining high levels of engagement.
Consistent in the PA profile findings [7, 10, 36], it was evident that motivation may be critical to PA engagement, particularly in adults engaging in higher intensity PA. For example, compared to all the other clusters, the High Intensity PA profile contained higher scores on autonomous forms of motivational regulation subscales (i.e., identified, integrated, and intrinsic regulation) for exercising and lower scores on controlling forms of behavior regulation subscales (i.e., external and introjected regulation). Autonomy is instrumental in regard to adults engaging in higher intensity exercise [7, 36]. Additionally, the findings from this study highlight the value and importance in assessing the quality of motivation (i.e., RAI score). More specifically, the High Intensity cluster had the highest RAI score followed by the Moderate Intensity and Walking PA clusters, confirming our hypotheses that not only is motivation important in more intense forms of PA, but the motivation quality may also be critical. Findings could be explained by the Dual-Mode Theory described by Ekkekakis [41] which postulates cognitive variables such perceived efficacy, goals, and expectations are more important as high intensity exercise levels are approached [42]. As perceived efficacy and reasons to exercise are heightened during high intensity activity, then autonomous motivation for exercise could increase, impacting the RAI score [9]. Enjoyment, mastery, and self-induced challenges were predicted more by intrinsic motivation in moderate and vigourous intensity exercisers, suggesting a higher RAI score in higher intensity exercisers. Further confirmations of these findings are best highlighted in Box, Feito, Brown, Heinrich, and Petruzzello in [7] suggesting that high intensity PA, similar to group exercise and sports, elicits intrinsic motivaiton (i.e., enjoyment, challenge), compeition, and relatedness factors.
Furthermore, the relatively low percentage of individuals falling into the High Intensity PA profile (~ 12% of the sample) reinforces the challenge of fostering vigorous PA engagement in the general population. Similarly, the Moderate Intensity PA profile represented ~ 11%, and the Walking profile included 10% of the population, whereas ~ 68% of the participants represented either the Low PA or Sitting profile. The Low PA profile had the lowest score in PA intensity categories and the lowest number of total PA per week. The Sitting profile represented the highest scores above the mean in time sitting across the groups. It is paradoxical that despite the inclusion criteria of this study being that participants must be engaging in PA or planning to start/restart PA, the sitting profile was the most prominent among an active population. This indicates that among a highly active group, individuals might not be engaging in as much activity as they might perceive. These findings also align with the prevalence of high sitting time and physical inactivity among U.S. adults. About 1 in 4 adults sit for more than 8 h a day, 3 in 4 are physically inactive, and 1 in 10 report both [43]. This higher level of low activity and sitting is even seen in a more highly active group. Evidence-based strategies to reduce sitting time, increase physical activity, or both would potentially benefit most sedentary U.S. adults.
Overall, our findings suggest a complex, bidirectional relationship between goals, motivation, and PA behavior. While initial goals may influence PA engagement, the intensity and type of PA can also shape and refine an individual’s goals and motivations over time. This highlights the importance of creating environments that not only encourage goal setting but also provide positive, intrinsically motivating PA experiences to sustain long-term engagement.
Summary
The study revealed distinct differences across physical activity (PA) profiles, with the High Intensity and Moderate Intensity PA clusters scoring the highest on mood enhancement, solitude, social, fitness, and competition reasons for exercise, significantly higher than sedentary participants. Interestingly, high-intensity exercisers valued both solitude and social connection, particularly in strength-training programs that emphasize autonomy within group settings. No differences were found across PA clusters for goals related to preventative health, weight management, appearance, or health concerns, suggesting these may be culturally shared forms of motivation. The findings also indicated that immediate satisfaction from PA-related outcomes, such as mood enhancement and social interaction, played a more critical role in maintaining high levels of PA compared to distal health goals. Autonomous motivation was highest in the High Intensity PA cluster, as evidenced by the highest Relative Autonomy Index (RAI) scores, underscoring the role of autonomy in sustaining high-intensity exercise. Finally, the majority of participants (68%) fell into the Sitting or Low PA profiles, highlighting the need for strategies to increase PA engagement and reduce sedentary behavior, even among those who identify as physically active.
Strengths, limitations, and future directions
The present study has important strengths, limitations, and implications to highlight. One primary strength was the large research sample studied, consisting of adults (e.g., motivated respondents) varying in age levels from 18 to 87 years of age. A future research direction would be to explore the mediating or moderating factors that influence the motivation around reasons for exercise. It may also be of interest to explore demographic differences within the clusters and how social factors might drive reasons for activity. The impact of behavior-change interventions encouraging exploration of values through practices like health coaching and peer mentorship might also be a promising research direction building on supportive work from researcher findings [44, 45].
As with any study, there were limitations in this research. First, the design of the study is cross-sectional and utilizes a convenience sample. However, the sample size and the participants recruited highlight that even exercisers perceived to be highly physically active may not be as active as health professionals believe them to be. Therefore, it is not possible to infer causal relationships from the results. Second, PA was assessed using a self-report measure. The limitations of this study include possible bias inherent in self-reported data and that physical activity episodes shorter than 10 min may not have been captured. Lastly, it must be emphasized that the subscales utilized in the Reasons to Exercise Scale (REX) are most likely not the only reasons adults have for exercising and/or being physically active. It should be noted that these motivation factors cannot be generalizable to those who are not physically active.
Practical implicaitons
The results of this study have several practical implications for public health interventions aimed at increasing PA engagement across populations. First, interventions that promote high-intensity PA should focus on intrinsic motivation by creating environments that foster enjoyment, social interaction, and a sense of personal accomplishment. For example, group-based high intensity training programs that balance social interaction with autonomy (e.g., individualized challenges within a group setting) may be particularly effective in promoting sustained engagement.
In addition, given that many participants across clusters still reported extrinsic goals such as weight management and health benefits, interventions should aim to reframe these goals in a more autonomous manner. For instance, encouraging participants to connect these types of external goals to personal values (e.g., improving health for long term wellbeing rather than appearance) may enhance their sense of ownership and autonomy, potentially leading to more sustained PA participation.
Lastly and most importantly, an essential aspect of interpreting these findings is that future research considers how motivation constructs can be adopted and integrated into interventions.
The Capability, Opportunity, and Motivation Behavior (COM-B) model offers a useful framework for understanding behavior change, positing that behavior results from the interaction of capability (physical and psychological), opportunity (physical and social), and motivation (reflective and automatic) [46, 47]. Applying the COM-B model in future research could clarify how motivations influence PA behavior and guide the design of interventions to boost engagement [48]. For instance, improving physical capability through strength training, enhancing psychological capability via self-efficacy, and fostering supportive social environments and intrinsic motivation could help sustain PA over time.
Future research directions
Future research should continue to investigate the interplay between PA intensity, motivation quality, and goals to better understand how these factors influence long-term PA engagement. Longitudinal studies that track changes in motivation and goal orientations over time as individuals progress through different stages of PA engagement would provide valuable insights into how PA can be sustained. Additionally, interventions that explicitly target the enhancement of intrinsic motivation (e.g., through autonomy-supportive environments) should be explored to determine their effectiveness in promoting higher intensity PA, especially among sedentary or minimally active populations.
Lastly, further exploration of the potential paradox between the sedentary behaviors observed in this study and participants’ reported intentions to engage in PA could shed light on barriers to PA engagement and inform strategies for reducing sitting time in both recreational and everyday contexts.
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