Aerobic training has been recommended to reduce overweight and obesity as risk factors for, metabolic and cardiovascular diseases, as well some types of cancer (Shilton et al., 2024). Overweight and obesity subjects have a 6-fold higher risk of developing type 2 diabetes and 3-fold higher risk of developing cardiovascular diseases compared to normal weight adults (Zhang et al., 2024). On the other hand, healthy lifestyle based on regular physical activity/exercise reduce overweight and obesity associated risks over 25 chronic diseases(Zhang et al., 2024; Khan et al., 2018; Hruby and Hu, 2015; Blüher, 2019), contribute to healthier aging (Shilton et al., 2024; Stafie et al., 2024; Albini et al., 2025; Elagizi et al., 2020; Yang and Petrini, 2018).

Physical inactivity contributes to the development of overweight and obesity, and negatively impact on health and quality of life (Almeida et al., 2024; Sacramento et al., 2024; Guthold et al., 2020). Globally, 7.2% of cardiovascular disease and 7.6% all-cause mortality are attributable to physical inactivity (Katzmarzyk et al., 2022). Psychophysiological determinants, such as motivation and physical limitations, are significant barriers to physical activity practice (Azizan and Fadzil, 2024).

Adherence to exercise programs in fitness centers has shown drop out between 40 and 70% of new participants within 3–6 months after starting (Sperandei et al., 2016; Gjestvang et al., 2019; Gjestvang et al., 2020; Gjestvang et al., 2021; Gjestvang et al., 2023). It suggests that current strategies to engagement have not been effective in addressing behavioral demands, as lack of intrinsic motivation, absence of personalized support, and enjoyment perception in training sessions (Sperandei et al., 2016; Gjestvang et al., 2019; Gjestvang et al., 2020; Gjestvang et al., 2021; Gjestvang et al., 2023; Clavel San Emeterio et al., 2019; Faro et al., 2023; Rodrigues et al., 2021).

Traditional exercise prescription models, as outlined in the guidelines (Liguori et al., 2021), prioritize safety and effectiveness but often fail to ensure long-term adherence. This has led to the proposal of a tripartite model that incorporates more enjoyable exercise doses to enhance engagement and promote greater future participation in training sessions (Ladwig et al., 2017; Ekkekakis and Tiller, 2022; Ekkekakis, 2017; Teixeira et al., 2012). Emotional factors, such as enjoyment during and after exercise and the satisfaction of achieving goals, are crucial motivators (Wienke and Jekauc, 2016), highlighting the need for strategies that foster positive emotional experiences (Rodrigues et al., 2021; Liguori et al., 2021; Ladwig et al., 2017; Teixeira et al., 2012; Wienke and Jekauc, 2016; Rodrigues et al., 2021; Teixeira et al., 2022; Ekkekakis et al., 2011; Williams et al., 2016). The Dual-Mode Theory (Ekkekakis, 2009) explains affective responses during aerobic exercise through two systems: automatic perception and cognitive control. As intensity increases beyond the ventilatory threshold, pleasure generally decreases. Positive affective responses can improve adherence, while negative experiences, such as discomfort, may lead to dropout (Williams, 2008; Ekkekakis and Lind, 2005; Parfitt et al., 2006; Hall et al., 2005).

Affective responses, whether pleasurable or discomforting, are central to the motivation for physical exercise. Behaviors with a greater perception of pleasure are more likely to be repeated, while displeasure may discourage engagement. Aerobic exercise intensities that generate positive emotions can contribute to greater adherence, whereas excessive effort or displeasure may lead to dropout. Therefore, exercise prescriptions should consider not only physiological benefits but also emotional responses, as these influence the decision to continue or discontinue training (Ladwig et al., 2017; Ekkekakis, 2003; Ekkekakis and Petruzzello, 1999; Rhodes and Kates, 2015; Williams and Evans, 2014). Affective valence, the spectrum of feelings ranging from pleasure to displeasure during activity, spans sensations that can enhance participation to those that discourage engagement (Russell, 2003). Emotions influence behavior through feedback, automaticity, and reflection; understanding these mechanisms is essential to comprehending how emotions can impact long-term adherence to physical exercise (Baumeister et al., 2007).

Positive social interactions and a supportive environment are crucial for promoting adherence to training programs (Gjestvang et al., 2020; Gjestvang et al., 2021; Gjestvang et al., 2023; Gabay and Oravitan, 2022; Withall et al., 2022). Small group exercise, a trend in fitness (Martinez Kercher et al., 2022), can enhance socialization and motivation, fostering a sense of community, as explained by Self-Determination Theory (Martinez Kercher et al., 2022; Wayment and McDonald, 2017; Spink et al., 2010; Golaszewski et al., 2022; Deci and Ryan, 2000). This theory identifies three psychological needs—autonomy, competence, and relatedness—as key elements of motivation. Autonomy, supported by self-selected exercise intensity, increases the sense of control and can improve affective responses, such as the perception of pleasure (Ekkekakis and Lind, 2005; Parfitt et al., 2006; Deci and Ryan, 2000; Ntoumanis et al., 2021). Together, these factors may influence the long-term maintenance of physical exercise practice, as individuals are more likely to continue activities aligned with their preferences and abilities (Williams and Evans, 2014; Ekkekakis et al., 2008; Lind et al., 2008).

Self-selected intensity promotes greater autonomy, allowing individuals to adjust their effort to align with their preferences. This approach is generally associated with more positive affective responses, such as enhanced pleasure and well-being (Parfitt et al., 2006). Self-selected intensity in aerobic training is effective in improving physiological and psychological aspects in different populations, such as obese women, adolescents and physically inactive older adults (Yang and Petrini, 2018; Barros et al., 2019; Alves et al., 2022). Physiological and psychological responses, including the perception of pleasure, in women with overweight or obesity during physical exercise is crucial for understanding the factors that influence adherence and motivation within this population.

Although previous studies (Ekkekakis, 2009; Ekkekakis and Lind, 2005; Lind et al., 2008; Ekkekakis et al., 2006) have investigated the differences between self-selected and prescribed exercise intensities, no prior research has compared self-selected protocols in small groups with individually prescribed ones, highlighting a significant gap in the literature.

The purpose of the present study is to compare the psychophysiological responses of overweight and obese women during aerobic training prescribed using two different methods: (A) prescribed intensities and (B) self-selected intensities, both in individual and small group settings. The primary hypothesis is that the intensity and training volume in prescribed group protocols will be similar to those in self-selected group protocols, both in individual and small group contexts. The secondary hypothesis is that self-selected intensity protocols will elicit more positive affective responses, such as higher affective valence, greater enjoyment, and increased intention to repeat exercise sessions, consistent with hedonic theory (Ekkekakis, 2003; Kahneman, 1999), which suggests that more pleasurable behaviors are more likely to be repeated. Additionally, it is expected that self-selected intensity groups will promote a greater perception of autonomy compared to the prescribed intensity group, as the possibility of choice is a central component of satisfying the need for autonomy, according to Self-Determination Theory (Deci and Ryan, 2000). Small group training is anticipated to promote a greater perception of relatedness compared to other groups, addressing the need for social connection and mutual support, while the perception of competence is expected to be similar across groups, as it relates to participants’ ability to accomplish the proposed tasks, aligning with the psychological need to feel effective and capable in their efforts (Deci and Ryan, 2000). These connections to basic psychological needs may explain how different protocols influence motivation and contribute to more positive experiences in aerobic exercise practice (Rodrigues et al., 2021; Ekkekakis, 2003; Rhodes and Kates, 2015; Ekkekakis et al., 2005; Lind et al., 2005).

A total of 102 participants were assessed for eligibility. Twelve participants were excluded for failing to meet the inclusion criteria (BMI >25 kg/m², n = 12; age > 40 years). Ninety participants were randomly assigned to the following groups: Control (IPI, n = 30), Individual with Self-Selected Intensity (ISS, n = 30), and Small Group with Self-Selected Intensity (SGS, n = 30). The recruitment process and protocol implementation took place over a period of 18 months. All data were collected prior to the end of June 2024.

The descriptive characteristics of the sample are presented in Table 2. The groups exhibited only minor differences in age and BMI. The SGS group had a lower mean age and a higher standard deviation compared to the other groups.

Heart rate data are presented in Table 3, with the mean HR during the exercise session remaining within the moderate intensity range for all groups: IPI = 70.5% HRmax, SGS = 70.3% HRmax, and ISS = 71% HRmax. The two-way ANOVA revealed a minimal interaction effect between group and time across the different groups (F = 1.17, p = 0.31, η² = 0.02).

The mean differences also did not reveal significant variations between the ISS and SGS groups when compared to the IPI group. The SGS group exhibited an average HR that was 0.3% lower than the IPI group (p = 0.98, mean difference = −0.21, 95% CI -3.81 to 3.38), while the ISS group had an average HR that was 0.7% higher than the IPI group (p = 0.66, mean difference = 1.32, 95% CI -4.92 to 2.27). These results support the primary hypothesis. The findings suggest that self-selected intensity is comparable to prescribed intensity, both classified as moderate (Liguori et al., 2021), and represent a safe and effective training approach for adult women beginning aerobic exercise programs, particularly those who are overweight or obese, as illustrated in Figure 3.

The volume load analyses of the aerobic training session are presented in Table 4. The one-way ANOVA showed a small interaction effect among the different groups (F = 0.87, p = 0.45, η² = 0.03).

The mean values also demonstrated similarities between the groups. The SGS group exhibited a 3.8% lower mean volume load recorded at the end of the exercise session (p = 0.28, mean difference = 0.08, 95% CI = −0.72 to 0.23), while the ISS group had a mean VL that was 2.9% lower compared to the IPI group (p = 0.12, mean difference = 0.12, 95% CI = −0.35 to 0.27). In support of our secondary hypothesis, the VL results were similar across the groups. These findings suggest that self-selected intensity is comparable to prescribed intensity regarding the total distance covered during the exercise session, as illustrated in Figure 4.

The analyses of the mean values of the Feeling Scale during the exercise session are presented in Table 5. Significant differences were found between the SGS and ISS compared to the IPI protocol, showing a moderate interaction effect between group and time across the different groups (F = 5.72, p = 0, η² = 0.09).

The SGS group demonstrated a 73.1% increase in mean Feeling Scale scores, excluding pre- and post-exercise session values (p = 0, mean difference = −1.1, 95% CI = −1.1 to −0.45), while the ISS group showed a 98.8% higher FS compared to the IPI group (p = 0, mean difference = −1.02, 95% CI = −1.34 to −0.7). In support of our secondary hypothesis, the FS results were significantly higher in both the SGS and ISS groups. These findings suggest that self-selected intensity is more enjoyable in both individual and small group settings. This indicates a more positive affective experience for women beginning physical training programs, particularly those who are overweight or obese, as shown in Figure 5.

A moderate effect was observed on the Physical Activity Enjoyment Scale, as presented in Table 6, indicating a significant interaction among the different groups (F = 5.57, p = 0, η² = 0.11). Comparisons between the SGS and ISS groups revealed significant differences when compared to the IPI group.

The SGS group exhibited a 9.4% increase in the mean PACES score administered at the end of the exercise session (p = 0, mean difference = −9.36, 95% CI = −16.17 to −2.55), while the ISS group showed an 8.5% higher mean compared to the IPI group (p = 0, mean difference = −10.36, 95% CI = −17.17 to −3.55). In support of our secondary hypothesis, the PACES results were higher in both the SGS and ISS groups, indicating that self-selected intensity is more enjoyable in both individual and small group settings for women with overweight and obesity starting aerobic training programs, as illustrated in Figure 6.

The analysis of the Intention to Repeat the Exercise Session (INT) is presented in Table 7. The one-way ANOVA revealed a moderate interaction effect among the different groups (F = 18.6, p = 0, η² = 0.39).

The mean values also revealed significant differences when compared to the control group. The SGS group exhibited a 41.6% increase in the mean INT score administered at the end of the exercise session (p = 0, mean difference = 1.8, 95% CI = −2.32 to −1.27), while the ISS group demonstrated a 37.6% higher mean INT compared to the control group (p = 0, mean difference = −1.63, 95% CI = −2.25 to −1.1). In support of our secondary hypothesis, the INT results were higher in both the SGS and ISS groups compared to the control group. These findings suggest that self-selected intensity increases the intention to repeat the exercise session three times in the following week, both in individual and small group conditions. This approach represents a training strategy that enhances the intention to repeat the behavior in the future for women with overweight or obesity who are initiating physical training programs, as depicted in Figure 7.

The analyses of the BPNSFS are presented in Table 8. The one-way ANOVA showed a large interaction effect among the different groups for autonomy (F = 290, p = 0, η² = 0.87).

The mean values also revealed significant differences when compared to the control group. The SGS group demonstrated a 16.36% increase in mean autonomy at the end of the exercise session (p = 0, mean difference = 1.8, 95% CI = −2.32 to −1.27), while the ISS group exhibited a 16.83% higher mean compared to the control group (p = 0, mean difference = −1.63, 95% CI = −2.25 to −1.1). In support of our secondary hypothesis, the autonomy scores were higher in both the SGS and ISS groups compared to the control group. These findings suggest that self-selected intensity enhances the perception of autonomy in both individual and small group settings when compared to the control group, as shown in Figure 8.

The one-way ANOVA revealed a large interaction effect between the groups for relatedness (F = 346, p = 0, η² = 0.88). The SGS group demonstrated a 206.8% increase in mean relatedness at the end of the exercise session (p = 0, mean difference = −10.96, 95% CI = −12.07 to −9.85), while the ISS group exhibited a 13.2% higher mean compared to the control group (p = 0.29, mean difference = −0.7, 95% CI = −1.81 to 0.29). This suggests that the ISS group had similar relatedness perceptions to the IPI.

The one-way ANOVA also revealed a small interaction effect for competence (F = 1.07, p = 0.34, η² = 0.02), with means showing minimal differences across the protocols. The SGS group demonstrated a 7.7% lower mean competence compared to the control group at the end of the exercise session (p = 0.35, mean difference = 1.20, 95% CI = 0.86 to 3.26), while the ISS group had a 3.1% lower mean competence compared to the control group at the end of the session (p = 0.96, mean difference = 0.23, 95% CI = −1.83 to 2.3). These results suggest that all groups had similar competence perceptions by the end of the exercise session.

Thus, the results indicate that self-selected intensity in both groups (SGS and ISS) positively impacted autonomy perception compared to the control group. The SGS group demonstrated more favorable results for relatedness perception compared to both the IPI and the ISS groups.

The SGS protocol elicited a higher response in the relatedness variable, which may be attributed to the perception of social bonding and support experienced in a small group exercise context. Such an environment facilitates positive social interactions and fosters a sense of belonging among participants, aligning with the relatedness need as defined by Self-Determination Theory (Deci and Ryan, 2000). This theory posits that social connection constitutes a fundamental pillar of intrinsic motivation, thereby enhancing engagement and promoting long-term adherence to exercise programs. These findings underscore the significance of integrating social components into exercise prescriptions, particularly for populations that may derive substantial benefits from increased social support and a strengthened sense of community.

For competence perception, no significant differences were observed, with all groups showing similar values.

The present study posits as its primary hypothesis that SGS and ISS would select an intensity similar to the control group (IPI), which followed the American College of Sports Medicine (Liguori et al., 2021) recommendations for moderate-intensity aerobic exercise prescription (64–76% of HRmax). The results support our primary hypothesis, as the mean heart rate values were similar across groups: control group IPI = 70.5% of HRmax, SGS group = 70.3% of HRmax, and ISS group = 71% of HRmax (p = 0.31, η² = 0.02). Our findings align with previous studies, such as Lind et al. (2005), which explored the relationship between self-selected intensity and prescribed moderate intensities. The results indicated that when allowed to choose, participants generally selected intensities similar to those recommended, suggesting that self-selection can align with prescribed intensity in terms of physiological benefits.

We did not find studies in the literature comparing total distance covered (training volume) in aerobic exercise between prescribed and self-selected intensities. Our study addresses this gap by showing that the volume load covered was similar across groups (p = 0.45, F = 0.87, η² = −0.03), with the SGS group covering 3.8% less distance than IPI (p = 0.28, mean difference = 0.08, 95% CI = −0.72 to 0.23). On the other hand, the ISS group covered 2.9% less distance than IPI (p = 0.12, mean difference = −0.35, 95% CI = −0.35 to 0.27).

In this context, we consider that self-selected intensity in aerobic exercise is a suitable prescription approach both from a physiological standpoint for sedentary adult women with overweight/obesity and in terms of affective responses (Ekkekakis and Lind, 2005; Parfitt et al., 2006; Lind et al., 2008; Ekkekakis et al., 2005). The evaluation of middle-aged sedentary women by Lind et al. (2005) showed that self-selected intensity corresponded to the prescribed recommendation for improving aerobic capacity, indicating that self-selection can achieve levels similar to those prescribed for this population.

In line with the tripartite exercise model of Ladwig et al. (2017), the dimensions of efficacy, safety, and pleasure support the hypotheses of the present study. Traditionally, exercise prescriptions focus on efficacy, ensuring that exercise promotes desired physiological adaptations, and safety, minimizing the risk of injury. However, low adherence to gym exercise programs is a widely recognized challenge (Sperandei et al., 2016; Gjestvang et al., 2019; Gjestvang et al., 2020; Gjestvang et al., 2021; Gjestvang et al., 2023), with dropout rates within the first 3–6 months, suggesting that current strategies may hinder adherence.

For older adults with chronic conditions, factors such as physical limitations and underlying health issues can pose significant barriers to participation in physical activities. Nevertheless, structured aerobic programs, such as walking, have been shown to enhance cognitive functioning and quality of life, emphasizing the potential of tailored interventions to improve exercise enjoyment and adherence (Cohen, 1988). These findings are consistent with our study, which demonstrated that small-group exercise elicited greater enjoyment compared to the IPI protocol. This highlights the critical role of social interaction in promoting positive affective responses and supporting sustained engagement in physical activity programs.

The perception of pleasure during exercise is a factor that optimizes long-term adherence, as enjoyable experiences during exercise generate positive affective responses associated with maintaining future behavior and intention to repeat exercise (Williams et al., 2016; Williams, 2008; Rhodes and Kates, 2015; Williams et al., 2008).

Our secondary hypothesis posits that self-selected intensity protocols (SGS and ISS) would result in higher affective responses compared to IPI. Our data showed that affective valence was higher in SGS and ISS (p = 0, F = 5.72, η² = 0.09), with SGS showing 73.1% higher exercise enjoyment compared to IPI (p = 0, mean difference = 0.78, 95% CI = −1.1 to −0.45). In ISS, affective valence during exercise was 98.8% higher than IPI (p = 0, mean difference = −1.02, 95% CI = −1.34 to 0.7).

Our findings are consistent with Ekkekakis and Lind (2005), who evaluated overweight and obese adults performing aerobic exercise sessions and found that affective valence in self-selected intensity was more positive than in prescribed intensity. Thus, we suggest that self-selection of aerobic exercise intensity should consider not only efficacy and safety but also the pleasurable nature of training. Parfitt et al. (2006) investigated sedentary adults in self-selected and prescribed intensity aerobic training with heart rate and pleasure/displeasure monitoring, demonstrating that self-selected intensity resulted in higher affective responses than prescribed intensity.

The Feeling Scale is a reliable tool for assessing self-selected intensity in aerobic training, especially for women in gym environments. Hamlyn-Williams et al. (2015) demonstrated that sedentary women effectively used the FS to regulate exercise intensity at moderate levels, predominantly experiencing positive affective responses. These findings suggest that the FS allows for real-time effort adjustment according to one’s emotional and physical state, promoting a more enjoyable experience. The potential of using the FS as an accessible tool for regulating exercise intensity appears to support and contribute to a pleasant exercise practice tailored to individual preferences.

As a mediator of successful interventions aimed at exercise continuity, enjoyment is associated with pleasurable experiences that increase the likelihood of adherence to training (Jekauc, 2015). Positive and enjoyable exercise experiences increase the probability of maintaining active behavior in the future, with previously experienced pleasure being a strong predictor of adherence (Rodrigues et al., 2021). The results of the present study showed that enjoyment was higher in the self-selected intensity groups SGS and ISS (p = 0, F = 5.57, η² = 0.11), with SGS 9.4% higher than IPI (p = 0, mean difference = 9.36, 95% CI = −16.2 to −2.55) and ISS 8.5% higher than IPI (p = 0, mean difference = 10.4, 95% CI = −17.2 to −3.55).

In this context, we understand that self-selected intensity results in greater enjoyment in adult women with overweight/obesity, indicating that it is a positive strategy for optimizing affective responses during exercise, as enjoyment is a predictor of future behavior related to physical exercise. Rodrigues et al. (2021) investigated how enjoyment influences exercise adherence, associating enjoyment with previous experiences and current exercise adherence. The results showed that enjoyment experienced in previous exercise sessions was a strong predictor of continuous adherence.

The experience of pleasure or discomfort during activity influences future intention for continued or discontinued exercise practice. The hedonic theory of human behavior associates that individual who maximize pleasure and minimize discomfort during exercise (Kahneman, 1999) have greater long-term adherence to training. Perceived pleasure fosters greater intrinsic motivation (Deci and Ryan, 2000), increasing the likelihood of adherence to sustained training commitment. The present study showed that the intention to engage in physical exercise three times in the following week, an indicator of future behavior, was higher in the SGS and ISS protocols compared to IPI (p = 0, F = 18.6, η² = 0.39). In SGS, the intention to repeat the exercise session three times in the following week was 41.6% higher (p = 0, mean difference = 1.8, 95% CI = −2.32 to −1.27) than IPI, while ISS was 37.6% higher than IPI (p = 0, mean difference = 1.63, 95% CI = −2.25 to −1.1). The results of the present study, based on the hedonic theory of human behavior (Ekkekakis, 2003), demonstrate that self-selected protocols were more positive in affective valence and enjoyment, suggesting better results in the intention to repeat the exercise session the following week (future behavior).

Our study suggests that self-selected exercise intensity may yield positive psychological and physiological responses, optimizing affective responses such as pleasure and reducing discomfort when compared to rigid exercise prescriptions. These findings align with those of Ekkekakis (2003), who demonstrated that more pleasant exercise experiences support long-term adherence, as well as promoting positive emotional experiences during training (Ekkekakis, 2009; Ekkekakis and Lind, 2005; Ekkekakis, 2003; Ekkekakis et al., 2006).

Given that adherence and continuity in exercise programs are influenced by motivational factors, Self-Determination Theory (Deci and Ryan, 2000) posits that human motivation and well-being are largely shaped by the satisfaction of basic psychological needs: autonomy, competence, and relatedness. Our results indicated that the perception of autonomy was significantly higher in the SGS and ISS groups compared to the IPI group (p = 0, F = 290, η² = 0.9). Specifically, the SGS group exhibited a 243.7% increase (p = 0, mean difference = −11.6, 95% CI –12.9 to −10.2), and the ISS group showed a 253.6% increase (p = 0, mean difference = 12, 95% CI 10.7 to 13.4) compared to IPI. Autonomy refers to the desire to feel responsible for one’s actions and choices, suggesting that allowing participants to self-select exercise intensity may be an effective strategy for fostering autonomy in exercise programs.

Regarding competence, which involves a sense of efficacy and skill development (Deci and Ryan, 2000), our results revealed no significant differences between groups (p = 0.34, F = 1.07, η² = 0). The SGS group showed a 7.7% lower perception of competence compared to IPI, and the ISS group was 3.1% lower than IPI. Although competence is associated with intrinsic motivation, Self-Determination Theory (Deci and Ryan, 2000) highlights that the perception of efficacy is a stronger predictor of exercise behavior. These findings suggest that participants felt capable of successfully performing the exercise session, regardless of the method used to determine intensity.

When comparing small group and individual training, we anticipated changes in the relatedness component, which refers to the connection and sense of belonging to others (Deci and Ryan, 2000). Small group training promotes a positive social environment, creating a sense of support and community. Social interaction in small groups can optimize motivation and may contribute to the continuation of the exercise program (Wayment and McDonald, 2017). In our study, the relatedness values for SGS and ISS were 206.8 and 13.2% higher than IPI, respectively, with no significant differences observed. Autonomous motivation, which encompasses the satisfaction of the psychological needs for autonomy, competence, and relatedness, could explain the maintenance of future exercise behavior (Rodrigues et al., 2021; Teixeira et al., 2012; Deci and Ryan, 2000). Psychological needs strengthen intrinsic motivation, which is associated with personal satisfaction and well-being (Ekkekakis et al., 2011; Deci and Ryan, 2000; Rodrigues et al., 2021), and a motivational environment that fosters these needs supports sustained exercise engagement.

The results of this study support the initial hypotheses, showing that protocols focused on self-selecting exercise intensity are a practical and effective approach to promoting motivational experiences and positive affect in overweight and obese adult women. This positive effect appears to contribute to sustained exercise adherence, a critical factor in improving long-term health and quality of life. Furthermore, our findings demonstrate that self-selected intensities yield physiological effects comparable to traditional exercise prescriptions, with similar total training volumes across both self-selected and prescribed intensity conditions. To the best of our knowledge, this is the first study to analyze this aspect in the scientific literature.

The SGS and ISS protocols were designed to stimulate competence development through skill acquisition and progress, as well as enhance interpersonal relationships. We understand that social interactions within small groups provide a sense of belonging and social support—factors that should be integrated into exercise program prescriptions to increase enjoyment and the likelihood of long-term adherence (Teixeira et al., 2012; Deci and Ryan, 2000). The study’s results revealed mean differences of 1 to 2 units on the Feeling Scale between the SGS and ISS groups, confirming a positive affective response to self-selected intensity protocols. These findings suggest that positive experiences during physical exercise may increase future physical activity levels (Williams et al., 2008). A one-point increase on the FS corresponds to an additional 27–29 min of physical activity per week, with further increases of 15–38 min per week after 6 months (Williams et al., 2012), potentially reaching up to 41 additional minutes per week after 12 months (Williams et al., 2008).

This study fills a gap in the literature by demonstrating that, even within small group contexts, self-selected intensity results in training volumes similar to those prescribed in traditional exercise prescriptions (Liguori et al., 2021). In addition to preserving exercise efficacy and safety, the small group format enhances social relationships, a psychological construct associated with autonomy and crucial in regulating active behavior. The social aspect of small group training fosters a perception of support, which contributes to long-term adherence and engagement (Teixeira et al., 2012; Deci and Ryan, 2000).

Thus, the results of the present study suggest that affective indicators should be considered in the selection of exercise intensity and volume in aerobic training prescription guidelines. While these guidelines are widely recognized (Liguori et al., 2021) and support individualized exercise, their integration with psychological variables remains limited. The various factors analyzed in the SGS and ISS protocols provide new insights into exercise psychophysiology and present a practical, evidence-based approach to intensity prescription, consistent with ACSM (2021) recommendations (Liguori et al., 2021). This approach emphasizes the prioritization of emotional experience in practitioners (Wienke and Jekauc, 2016).

The SGS and ISS protocols employed in this study, which allowed participants to self-select their exercise intensity during aerobic exercise, resulted in higher perceived autonomy compared to the IPI group (p < 0.05). This indicates greater efficacy in the affective experience of exercise, factors which may promote health and improve physical fitness (Hamlyn-Williams et al., 2015; Costa et al., 2015). Among the strengths of the study are: (Shilton et al., 2024) the similarity in intensity and volume between the SGS and ISS groups, which suggests that small group training is a safe and enjoyable alternative to individual exercise at self-selected intensity, comparable to traditional prescription; and the importance of fostering autonomy and social relationships in the small group protocol, particularly when participants share similar demographics, such as age and sex, as in the present study.

Achieving sustainable behavior change requires longitudinal analyses, as participants may drop out or experience relapse over time. We believe that this study could inform future interventions that extend the monitoring period and track engagement with training sessions. Future research should investigate the efficacy of this intervention in longitudinal contexts, assessing adherence, frequency, and effects on fitness changes in supervised environments.

The main findings of the present study indicate that the intensity and training volume were comparable across the IPI, SGS, and ISS protocols, demonstrating that self-selected intensity is biologically equivalent to prescribed intensity. Affective responses, including pleasure, enjoyment, and intention to repeat the activity, were more positive in the self-selected intensity protocols. This underscores self-selection as a safe, effective, and more enjoyable alternative to prescribed intensity in aerobic training. Moreover, self-selection facilitated greater autonomy, a core construct for sustaining exercise behavior, as outlined by Self-Determination Theory. Small-group training with self-selected intensity emerged as an effective approach, enhancing both autonomy and relatedness—key components of Self-Determination Theory—which may contribute to improved adherence to aerobic exercise routines. These findings present practical strategies that can be implemented in fitness centers and public health programs to promote sustained physical activity participation.

The findings of the present study suggest that exercise professionals working with obese women should implement individualized, participant-centered strategies. Allowing participants to self-select exercise intensity within safe parameters can enhance feelings of pleasure and autonomy, while incorporating small-group sessions can strengthen social support and foster a sense of connection. Regular monitoring of affective responses, such as valence and pleasure, is crucial for adjusting sessions to optimize enjoyment and effectiveness. Furthermore, creating a supportive and inclusive environment, setting realistic and attainable goals, and ensuring gradual progression in exercise programs can enhance intrinsic motivation and promote long-term adherence, consistent with the principles of Self-Determination Theory.

A key limitation of the present study is its cross-sectional design and the small sample size, comprising overweight/obese adult women, which restricts the generalizability of the findings to other populations, such as men or younger individuals. Additionally, the short-term nature of the study and reliance on self-reported psychological measures represent notable limitations. While the findings suggest that self-selected intensity and small-group training promote positive affective experiences and may enhance exercise adherence, it remains uncertain whether these effects are generalizable to individuals with chronic conditions or to different age groups. Future research should investigate the efficacy of this psychophysiological approach in diverse demographic contexts. Furthermore, longitudinal studies are needed to assess the effectiveness of self-selected intensity in sustaining exercise behavior over time and across various exercise modalities, such as resistance training, to expand and solidify the practical applications of this strategy in promoting physical activity adherence.

The findings of the present study suggest that self-selected intensity in aerobic exercise, whether in individual or small group settings, is a feasible and more effective strategy for promoting positive affective experiences in overweight/obese women, without compromising standard recommendations for exercise intensity and volume. Self-selection not only results in intensity levels comparable to traditional prescriptions but also significantly increases perceived pleasure and the intention to repeat the exercise, factors that may enhance adherence to training.

Moreover, the small group model was equally effective, adding the benefit of fostering social relationships, which are linked to better behavioral regulation and more intrinsic motivation for exercise. These findings indicate that exercise prescription strategies incorporating autonomy and social support can be more effective, particularly for populations facing barriers to engagement in exercise programs, such as overweight/obese women.

In summary, this study advances our understanding of psychophysiological responses to aerobic exercise and underscores the importance of integrating pleasure and social support into exercise guidelines. This is especially relevant for groups that may benefit from a more supportive and flexible training environment tailored to individual preferences.

We thank CAPES, Coordination for the Improvement of Higher Education Personnel for promoting the research project and São Judas Tadeu University for providing the laboratory for data collection.