Ambivalence is Associated With Decreased Physical Activity and Cardiorespiratory Fitness Among Adolescents with Critical Congenital Heart Disease

Abstract

Background:

Adolescents with congenital heart disease (CHD) are insufficiently physically active. Given that increasing physical activity may reduce their cardiovascular risk, it is important to identify correlates of this behavior. Perceived benefits of and barriers to physical activity are associated with physical activity engagement. Existing research has only considered these constructs separately. This population may be ambivalent toward physical activity (i.e., perceive both strong benefits and barriers). The association of ambivalence and physical activity related outcomes is unknown among this at-risk population.

Objective:

Determine the association of ambivalence and sedentary behavior, moderate-to-vigorous physical activity (MVPA), and cardiorespiratory fitness (VO_2Peak) among adolescents with CHD.

Methods:

The present study is an analysis of data from an eligibility assessment for a randomized clinical trial of an intervention to promote MVPA among adolescents aged 15 to 18 years with moderate or complex CHD. Participants (N=84) completed a survey assessing perceived benefits and barriers from which ambivalence toward physical activity was calculated, an exercise stress test to measure VO_2Peak, and wore an accelerometer for one week to determine their engagement in sedentary behavior and MVPA. Linear regression analyses determined associations between ambivalence and physical activity related outcomes.

Results:

Greater ambivalence toward physical activity was associated with increased sedentary behavior, decreased MVPA, and reduced VO_2Peak, adjusting for demographic and clinical covariates.

Conclusions:

Ambivalence is associated with objectively measured physical activity (sedentary behavior, MVPA) and a biomarker of cardiovascular health (VO_2Peak). Screening for ambivalence may help clinicians identify those most likely to benefit from physical activity-related education.

Introduction¹

Adolescents with congenital heart disease (CHD) are less physically active than healthy peers,¹ despite physical activity being safe and recommended for most in this population.² Low physical activity engagement exacerbates heightened risk of future cardiovascular complications for adolescents with CHD.³ Thus, understanding factors that relate to physical activity among adolescents with CHD is vital for reducing the cardiovascular risk of this vulnerable population.

Healthy adolescents identify perceived benefits (e.g., having fun) that promote and perceived barriers (e.g., lack of time) that hinder physical activity ⁴. Existing research has focused on the individual contributions of benefits and barriers to physical activity; however, these constructs should also be considered jointly. That is, adolescents may perceive both strong benefits and strong barriers to physical activity. This ambivalence may be particularly important for physical activity engagement among adolescents with CHD as they experience increased health-related anxiety⁵ and parental overprotection ⁶ that may enhance perception of barriers. In the presence of these barriers, adolescents with CHD may also perceive strong benefits given that most affected by childhood illness regard physical activity as beneficial ⁷.

While ambivalence toward physical activity has not been investigated among healthy adolescents or adolescents with CHD, prior research has identified relationships between ambivalence and physical activity among adults. Ambivalence is negatively associated with frequency of health club attendance ⁸, moderate-to-vigorous physical activity (MVPA) measured by accelerometer ⁹, and self-reported physical activity ¹⁰ in other populations. Ambivalence may also be an important consideration for adolescent physical activity because it has implications for models of health behavior change. The Theory of Planned Behavior, which posits that attitudes, subjective norms, and perceived behavioral control predict behavioral intent and ultimately engagement,¹¹ is an established framework for explaining physical activity among adolescents, including those with pediatric illness.¹² Among adolescents, positive attitudes toward physical activity predict increases in objectively measured physical activity,¹³ but ambivalence has been shown to attenuate the relationship between attitudes and behavioral engagement as outlined by the Theory of Planned Behavior.¹⁴ In addition, ambivalence has been connected to the Transtheoretical Model,¹⁵ which outlines stages of behavioral change. Ambivalence has been associated with readiness to engage in health-promoting behavior among adolescents, such that ambivalence is highest when adolescents are contemplating or preparing to change their behavior and lowest when they are currently engaging in or maintaining the behavior.¹⁶ Hence, an ambivalent attitude toward physical activity may undermine adolescents’ physical activity engagement by weakening relationships known to lead to behavioral engagement or preventing adolescents from progressing toward enacting behavioral change.

Given the elevated potential for ambivalent attitudes toward physical activity among adolescents with CHD, it is critical to consider how ambivalence relates to physical activity in this at-risk population. To the best of our knowledge, existing research has not examined ambivalence about physical activity among adolescents nor among individuals with CHD. The aim of the present study was to determine the association of ambivalence and objectively measured sedentary behavior, MVPA, and cardiorespiratory fitness (VO_2Peak) among adolescents with CHD.

Methods

The current study is an analysis of cross-sectional, observational data from the baseline eligibility assessment for a randomized clinical trial of a coach-led, eight-session, videoconference-delivered intervention informed by the Theory of Planned Behavior to promote MVPA among adolescents with critical CHD (NCT03335475). Methods for the baseline eligibility assessment that is the focus of the present analysis are described briefly below and in detail elsewhere ¹⁷. At the time of their participation in activities for the present analysis, participants had not been determined eligible for, consented to, or exposed to procedures for the randomized clinical trial.

Participants and Procedures

Adolescents were identified from outpatient cardiology clinic rosters for all providers at a Midwestern pediatric hospital and were screened via medical records according to eligibility criteria: 1) 15-18 years old, 2) moderate (e.g., tetralogy of Fallot, bicuspid aortic valve) or complex CHD (e.g., transposition of the great arteries, single ventricle) ¹⁸, 3) ability to complete an exercise stress test, and 4) home address ≤ 120 miles from the study site. Exclusion criteria included: 1) not proficient in the English language, 2) cognitive impairments interfering with ability to complete study measures, 3) genetic syndrome, 4) recent (≤ 6 months) engagement in a formal exercise program, 5) recent (≤ 3 months) open-heart surgery or transcatheter valve replacement, 6) prohibited by cardiologist to engage in at least moderate physical activity, and 7) currently pregnant. Eligibility was confirmed with the primary cardiologist of adolescents who appeared eligible for the study based on medical record review. Of 143 potential participants approved for participation by their cardiologist, seven were discovered to be ineligible upon contact (moved outside study area: n = 3; unable to complete stress test: n = 1; enrolled in other exercise program: n = 1; not proficient in English: n = 1; and pregnant: n = 1) and 17 were unreachable. Of the 119 adolescents approached for participation, 89 provided informed assent/consent. Reasons for non-participation included: decline (n = 16) and unable to schedule/attend stress test (n = 14). One participant was withdrawn after enrolling due to not having structural CHD, resulting in a final recruitment rate of 74.6% among eligible adolescents. Adolescents who enrolled in the study were not different than those who did not enroll on age (p = .816), gender (p = .237), race p = .471), ethnicity p = .443), or lesion severity p = .513). Participants completed an online survey, an exercise stress test, and wore an accelerometer for one week as part of an eligibility assessment for a physical activity trial.

Outcomes

Benefits and Barriers

The Benefits to Physical Activity questionnaire¹⁹ and the Barriers to Exercise questionnaire²⁰ assessed benefits (e.g., reduce disease risk, improve heart and lung fitness, do better at school) and barriers (e.g., lacking motivation, lacking friend/family support, feeling tired) to physical activity that are developmentally appropriate and relevant for adolescents with CHD. Both used a 1 (“Strongly Disagree” [Benefits] / “Not true at all for me” [Barriers]/ “to 5 (“Strongly Agree” [Benefits] / “Very true for me” [Barriers]) scale, with higher mean scores reflecting greater perceived benefits or barriers. The Barriers to Exercise questionnaire was modified to use the term “physical activity” instead of “exercise.” The Benefits to Physical Activity questionnaire has shown associations with physical activity among adolescent and adult samples,^4,21 indicating good convergent validity. Excellent internal consistency reliability was observed for the Benefits to Physical Activity (α = .95) and Barriers to Exercise (α = .96) questionnaires in the present study.

Ambivalence.

The formula proposed by Thompson and colleagues ²² determined ambivalence based on mean ratings of perceived benefits and barriers, which served as proxies for positive and negative evaluations of physical activity. In the present study, the formula is: $Ambivalence=\frac{\left(Benefits+Barriers\right)}{2}-\left|Benefits-Barriers\right|$. The formula described by Thompson and colleagues has been used to assess ambivalence related to other behavioral targets (e.g., substance use) among adolescents¹⁰ and has been used in recent studies of physical activity. ^9,10 The formula captures the relative intensity and similarity of benefits and barriers; thus, the greatest ambivalence is observed when the benefit and barrier ratings are both strongly endorsed and close in strength. The range of possible values was −1 (low) to 5 (high).

Sedentary Behavior and MVPA

A triaxial accelerometer (ActiGraph wGT3X-BT) worn around the waist measured sedentary behavior and MVPA. Data were considered valid if the device was worn for ≥ eight hours per day, excluding any nighttime wear, on ≥ four days, including ≥ one weekend day. Adherence to wearing the accelerometer was tracked in real time with an actigraphy monitoring platform (CentrePoint), and, if necessary, study staff contacted participants to remind them to wear the device. If participants returned the accelerometer without having worn it according to the requirements described above, they were asked to wear the accelerometer again and this data was used in the analysis. Data were analyzed with Actilife 6.13.3 and the Evenson et al. ²³ and Choi et al. ²⁴ algorithms for sedentary behavior and MVPA, respectively.

Cardiorespiratory Fitness (VO_2Peak)

Adolescents completed a treadmill exercise stress test that used the half Bruce protocol²⁵. VO_2Peak (mL/kg⁻¹ per min⁻¹) was determined by the highest VO₂ in an eight-breath rolling average. Higher VO_2Peak values reflect better cardiorespiratory fitness.

Demographic and Clinical Characteristics

Demographic characteristics (i.e., age, race, gender) were self-reported. CHD lesion severity was abstracted from medical records. Height and weight measurements used to calculate body mass index (BMI) were obtained at the time of the exercise stress test.

Statistical Analysis

Prior to performing statistical analysis, data were examined for missingness. Of 88 participants, accelerometer (n = 2) and/or ambivalence (n = 4) data were missing for a total of four adolescents. Thus, the final sample was composed of 84 adolescents who had accelerometer and ambivalence data available for analysis. Two of these 84 adolescents had missing VO_2Peak data but are included in analyses for sedentary behavior and MVPA. Data on barriers were pro-rated using mean replacement for two adolescents who completed 23 of 24 barrier measure items and are included in the final sample of 84.

T-tests and bivariate correlations assessed the relationship between demographic factors (i.e., age, gender, race, lesion severity) and ambivalence. To determine the unique association between ambivalence and physical activity-related outcomes (i.e., sedentary behavior, MVPA, and, VO_2Peak), ambivalence was entered into three separate linear regression models with gender and BMI, which are established correlates of physical activity ^17,26, and severity of CHD lesion as an indicator of disease status. MVPA was included in the VO_2Peak model given its relationship with cardiorespiratory fitness ²⁷. List-wise deletion excluded those with missing data from the models. Examination of scatterplots revealed that the assumptions of linearity and homoscedasticity were met, and variance inflation factor statistics indicated no multicollinearity. P-P plots indicated that the residuals were normally distributed. Post-hoc sensitivity analyses were conducted to determine if the association between ambivalence and physical activity outcomes differed according to demographic characteristics. The threshold for statistical significance was p < .05. Analyses were performed with SPSS version 26.

Results

Adolescents were an average age of 16.2 years (SD =1.0), primarily White (85.7%), male (60.7%), and had moderate CHD (70.2%). The most common lesions were bicuspid aortic valve (38.1%), coarctation of the aorta (20.2%), and aortic valve stenosis (14.3%); 7.1% of the sample had a Fontan procedure. One-third of the sample (33.3%) had overweight/obesity (M_BMI = 23.9, SD = 5.3). Additional demographic and clinical characteristics for the entire baseline eligibility assessment sample are described elsewhere.¹⁷

The mean ambivalence value was 1.2 (SD = 1.4, range: −1.0 – 3.6). Females (M = 1.69, SD = 1.40) reported greater ambivalence than males (M = 0.93, SD =1.28) (p = .013, d = 0.56), but ambivalence did not differ by lesion severity (p = .309) or race (White vs. Other Race; p = .142) and was not associated with age (p = .963). Descriptive statistics for sedentary behavior, MVPA, and VO_2Peak are presented in Table 1.

Table 1.

Association of Ambivalence With Sedentary Behavior, MVPA, and VO_2Peak.

	M (SD)	b	SE of b	95% CI of b	β	95% CI of β	p	R2
Sedentary Behavior, minutes per day	565.8 (103.5)
Unadjusted Model (n = 84)								.07
Ambivalence		19.22	8.07	[3.16, 35.27]	0.25	[0.04, 0.47]	.020
Adjusted Model (n = 84)								.08
Ambivalence		19.53	8.73	[2.15, 36.91]	0.26	[0.03, 0.49]	.028
Gendera		1.99	23.73	[−45.25, 49.22]	0.01	[−0.44, 0.48]	.934
BMI		−1.64	2.16	[−5.95, 2.67]	−0.08	[−0.31, 0.14]	.451
Lesion severityb		25.93	24.54	[−22.91, 74.77]	0.12	[−0.22, 0.72]	.294
MVPA, minutes per day	22.2 (15.3)
Unadjusted Model (n = 84)								.13
Ambivalence		−3.97	1.15	[−6.27, −1.68]	−0.36	[−0.56, −0.15]	.001
Adjusted Model (n = 84)								.18
Ambivalence		−3.11	1.22	[−5.54, −0.68]	−0.28	[−0.50, −0.06]	.013
Gendera		−7.47	3.32	[−14.07, −0.87]	−0.24	[−0.92, −0.06]	.027
BMI		𢈒0.18	0.30	[−0.78, 0.42]	−0.06	[−0.27, 0.15]	.557
Lesion severityb		0.64	3.43	[−6.19, 7.46]	0.02	[−0.40, 0.49]	.853
VO2Peak	37.0 (9.7)
Unadjusted Model (n = 82)								.37
Ambivalence		−4.31	0.62	[−5.55, −3.07]	−0.61	[−0.79, −0.43]	.000
Adjusted Model (n = 82)								.70
Ambivalence		−2.65	0.49	[−3.62, −1.67]	−0.38	[−0.51, −0.24]	.000
Gendera		−2.89	1.32	[−5.52, −0.25]	−0.15	[−0.57, −0.03]	.032
BMI		−0.62	0.12	[−0.85, −0.39]	−0.34	[−0.47, −0.21]	.000
Lesion severityb		−7.13	1.34	[−9.81, −4.46]	−0.34	[−1.01, −0.46]	.000
MVPA		0.14	0.04	[0.05, 0.23]	0.22	[0.09, 0.36]	.002

Note. BMI = body mass index; MVPA = moderate-to-vigorous physical activity

^aMale gender is the reference category.

^bModerate CHD lesion severity is the reference category.

As shown in Table 1, greater ambivalence toward physical activity was independently associated with increased sedentary behavior, decreased MVPA, and reduced VO_2Peak. Because female participants reported greater ambivalence toward physical activity, post-hoc sensitivity analyses were conducted to determine if the associations between ambivalence and physical activity outcomes varied by gender. However, the relationship between ambivalence and sedentary behavior (p = .412), MVPA (p = .999), and VO_2Peak (p = .392) was the same for females and males.

Discussion

In the context of recent reports of increasing sedentary time and decreasing physical activity among adolescents with CHD ^28,29, it is critical to identify correlates of these behaviors. The present study found that ambivalence toward physical activity was related to increased sedentary behavior, decreased MVPA, and poorer cardiorespiratory fitness among adolescents with critical CHD. The present study is the first, to the best of our knowledge, to investigate the association between ambivalence with physical activity outcomes among adolescents, including both healthy and pediatric populations.

The observed relationship between ambivalence toward physical activity and increased sedentary time is notable, considering that sedentary behavior is associated with elevated risk for poor cardiovascular and other adverse health outcomes, regardless of physical activity ³⁰. Further, among youth with CHD, sedentary behavior is associated with increased odds of central adiposity ³¹, a cardiometabolic risk factor. Ambivalence was the only significant correlate of sedentary behavior identified, corresponding to a nearly 20-minute per day increase in sedentary time for every one-point increase in ambivalence. While there is insufficient evidence to determine whether there is a dose-response relationship between sedentary behavior and negative health outcomes for youth, such a relationship has been found for adults ³². Thus, ambivalence may be a valuable indicator of adolescents with increasing levels of sedentary behavior and who may be at risk for poor health outcomes as they age into adulthood.

The identification of ambivalence as an individual-level correlate of sedentary behavior is also notable because most research on adolescent sedentary behavior has focused on environmental level correlates, such as home, school, and community factors.³³ A review of sedentary behavior interventions found that interventions targeting only sedentary behavior were superior to those addressing physical activity in reducing sedentary time,³⁴ indicating that distinct motivational processes may underlie sedentary behavior and physical activity engagement and that principles for reducing sedentary behavior and increasing physical activity cannot be applied interchangeably. Strategies to reduce ambivalence toward physical activity may be important considerations for interventions that aim to decrease sedentary behavior.

Ambivalence toward physical activity was also associated with reduced MVPA. While other research has shown that barriers reduce and benefits promote physical activity among adolescents,⁴ the current study is the first to our knowledge to demonstrate that the similarity and intensity of perceived barriers and benefits of physical activity (i.e., ambivalence) is related to reduced MVPA among the cardiovascular at-risk group of adolescents with CHD. This finding is consistent with work from another cardiac population showing that ambivalent attitudes are negatively associated with physical activity ⁹. The health benefits of MVPA across the lifespan ^35,36 are well-established and may be particularly important for reducing risk for acquired cardiovascular complications among individuals with CHD. Evidence indicates a dose-response relationship between MVPA and markers of cardiovascular health among adolescents ³⁷. Thus, the observed three-minute decrease in daily MVPA associated each one-point increase in ambivalence may threaten the cardiovascular health of adolescents with CHD.

Finally, adjusting for gender, BMI, and lesion severity, ambivalence toward physical activity was associated with cardiorespiratory fitness (VO_2Peak), an important biomarker of cardiovascular health that is directly impacted by physical activity behavior ³⁸. VO_2Peak predicts mortality and hospitalization ³⁹ and is associated with decreased health-related quality of life ⁴⁰ among individuals with CHD. Because VO_2Peak is reflective of longer-term behavior, this finding implies that ambivalence is correlated with both long (VO_2Peak) and short-term (weekly MVPA) indicators of physical activity engagement.

In the present study, ambivalence was operationalized as the similarity and intensity of perceived benefits and barriers of physical activity such that adolescents endorsing high perceived benefits and high perceived barriers, for example, had high ambivalence scores. Interestingly, this notion indicates that, despite having strong perceptions of benefits, adolescents with strong perceptions of barriers demonstrated reduced physical activity in terms of increased sedentary time and decreased time spent in MVPA and poorer cardiorespiratory fitness. Hence, perception of benefits alone may be insufficient to motivate adolescents be physically active, and ambivalence may undermine physical activity engagement even in the presence of strongly perceived benefits. Indeed, research on other health behaviors has demonstrated that attitudinal ambivalence attenuates the relationship between attitude toward a behavior and behavioral intention and engagement.¹⁴

Limitations

The use of objective physical activity measurements, inclusion of an indicator of health status (i.e., VO2_Peak), and the examination of physical activity among a cardiovascular at-risk population elevate the rigor and significance of the present research, but some methodological limitations must be considered. While the formula used to calculate ambivalence is frequently used in the literature, the use of perceived benefits and barriers as proxies for positive and negative attitudes toward physical activity may not fully capture the construct of ambivalence as it relates to physical activity. Similarly, the ambivalence formula used yields an indicator of “objective” ambivalence (i.e., presence of both negative and positive attitudes) and may have a different relationship with physical activity than “subjective” ambivalence (i.e., the conscious experience of conflicting attitudes), which was not assessed. In addition, participants were sampled from adolescents engaged in follow-up cardiology care and who agreed to participate in physical activity research. Those engaged in cardiology follow-up and willing to participate in physical activity research may have more positive orientations toward physical activity than other adolescents. While a high recruitment rate was achieved, the possibility that adolescents who enrolled in the study may have different physical activity perceptions and behaviors than those who did not cannot be eliminated. Moreover, the sample lacked racial diversity and thus may not reflect the physical activity or ambivalence of all adolescents with CHD. Finally, the observed sedentary behavior and MVPA, although assessed objectively via accelerometry, reflect behavior during a single week that may not be representative of adolescents’ typical physical activity.

Clinical Implications and Future Directions

The present findings imply that increased ambivalence may detect those with low physical activity and thus who are at risk for poor long-term health outcomes. This consideration is important because adolescent self-report of physical activity is unreliable ⁴¹, and lack of time and training prevent cardiology providers from discussing physical activity during clinical encounters ⁴². Hence, brief screening of correlates of low physical activity (e.g., ambivalence) may help clinicians identify those most likely to benefit from physical activity-related education, thereby conserving resources. Such screening could occur during the transition education process as adolescents with CHD prepare to enter adult cardiology care and take more responsibility for their own health. Adolescents with CHD who report elevated ambivalence toward physical activity may receive additional education about the importance of physical activity to their long-term cardiovascular health. In addition, adolescents with heightened ambivalence may benefit from working with cardiology providers to help identify and set appropriate physical activity goals during the transition process. Progress toward these goals could be assessed at follow-up appointments, and additional education and resources could be provided if barriers to achieving goals are encountered.

While inferences about the nature of the association of ambivalence and physical activity cannot be made from the current cross-sectional data, it has been theorized that ambivalence is part of the behavioral change process ⁴³. Indeed, cardiovascular at-risk patients express ambivalence about lifestyle change, including increasing physical activity, after preventive cardiovascular consultations ⁴⁴. Further, primary care patients commonly express ambivalence when physical activity is assessed during clinical encounters, but physicians do not provide appropriate assistance, often responding in an avoidant manner or changing the subject.⁴⁵ Thus, cardiology providers may benefit from training on approaches to respond to ambivalence and effectively communicate with patients about physical activity, which may help facilitate successful referral to physical activity programming. The extent to which ambivalence is modifiable and can be mitigated to reduce sedentary time and increase MVPA among adolescents with CHD within the cardiology setting is a topic for future research.

Motivational Interviewing (MI), a counseling approach that aims to resolve ambivalence about behavioral change and has been used to promote a variety of health-related behaviors ⁴³, may be an appropriate strategy to enhance physical activity and reduce cardiovascular risk among adolescents with CHD as they age into adulthood. MI is well positioned for implementation in cardiology settings because it is brief, goal-focused, and can be delivered by a variety of healthcare professionals.⁴⁶ There have been no clinic-based MI interventions to increase physical activity among adolescents with CHD, but other MI research has been conducted. Two small trials of MI style interventions to increase physical activity among adolescents with CHD have yielded contrasting findings. McKillop and colleagues⁴⁷ found no effect of individual telephone MI sessions on physical activity. However, most participants were in the maintenance stage of change, during which ambivalence may be lower,¹⁶ and thus may have had limited opportunity to benefit from the intervention. In contrast, Morrison and colleagues⁴⁸ reported that a group MI style session was associated with significant increases in MVPA compared to the control group. Neither of these studies examined ambivalence, however, underscoring the need for research investigating the association between ambivalence and change in physical activity, which may help refine interventions to increase physical activity among adolescents with CHD.

Given that they reported greater ambivalence and are less physically active than males,¹⁷ female adolescents, in particular, may benefit from intervention to promote physical activity. In addition, ambivalent attitudes are more amenable to influence,⁴⁹ indicating that female adolescents may derive greater benefit from MI based interventions. Thus, adolescent girls with CHD may benefit from referral to relevant physical activity education and programming.

Because the present study is the first to address ambivalence toward physical activity among adolescents with CHD, additional research is needed to confirm the present findings and answer additional important questions. First, future work should investigate subjective ambivalence toward physical activity to determine if its association with physical activity outcomes differs from that of objective ambivalence as observed in the present study. Second, longitudinal research is needed to ascertain if the relationship between ambivalence and physical activity outcomes changes over time as adolescents enter young adulthood and experience changes in their physical activity levels. Third, ambivalence about physical activity among adolescents with CHD should be examined in the context of health behavior theories (e.g., Theory of Planned Behavior, Transtheoretical Model). Findings from this work may help refine theory-driven interventions to promote physical activity among cardiovascular at-risk adolescents with CHD. Fourth, future research should ultimately determine if clinic-based MI-informed interventions can mitigate ambivalence about physical activity, reduce sedentary behavior, and increase MVPA among adolescents with CHD. Finally, future research must recruit more diverse participant samples that represent the population of adolescents with CHD to improve generalizability. In addition, representative samples will permit investigation of potential differences in ambivalence among of racial and ethnic minorities and other underserved populations, which may provide valuable information for tailored interventions. Of note, cultural adaptations of MI have been effective for a variety of health behaviors,⁵⁰ further highlighting reducing ambivalence as a potential target of intervention for promoting physical activity for the population of adolescents with CHD.

Highlights:

• Greater ambivalence toward physical activity was associated with decreased MVPA

• Greater ambivalence toward physical activity was related to more sedentary time

• Greater ambivalence toward physical activity was associated with poorer VO_2Peak