Results from the present study support the psychometric validity and reliability of the 30-item Mental health-related barriers and benefits to EXercise (MEX) scale. Additionally, the two 15-item subscales (benefits, and barriers), are each well supported psychometrically within the present analysis. Both subscales have high item loadings and high internal consistency, whilst the scale as a whole showed excellent discriminant and convergent validity. The novel MEX scale fills an important gap in the literature regarding the quantification of depression and anxiety-related barriers and benefits to exercise engagement, which are well documented in qualitative research (e.g. Mason et al., 2015; Searle et al., 2011), but not in quantitative research.
There was a robust positive association in sample 1 among benefits and total physical activity (PA; i.e., a summation of weekly leisure-time exercise, as well as work, transport, or other non-leisure-time physical activity across an average week). In sample 2/3, there was also a robust positive association between the MEX benefits and leisure-time exercise. These results are important in showing the convergent validity of the MEX in terms of both overall PA, and in leisure-time physical activity, in particular. Similarly, barriers to exercise engagement were robustly positively associated with anxiety- and depression-like symptoms in both datasets, and negatively associated with leisure-time exercise in sample 2/3. In both datasets, barriers were significantly more associated with symptoms of affective distress than were the benefits.
Given the number of overall correlations, only those significant at a threshold of p < .001 are considered in detail. In sample 1, results demonstrated a moderate positive correlation between benefits of exercise and satisfaction with life as predicted. Similarly, benefits of exercise were positively associated with total PA and subjective perception of fitness, suggesting that beliefs about benefits of exercise are related to both actual exercise engagement and the subjective estimates of one’s physical fitness and PA levels. Barriers, on the other hand, were strongly positively correlated with anxiety-like symptoms, depression-like symptoms, and self-reported levels of stress. This result implies that as symptoms of mental ill health increase, so too does one’s experience of mental health-related barriers to exercise engagement. The trend is particularly important to recognise as it further highlights the additional and unique barriers to exercise faced by individuals who experience symptoms of anxiety and depression, as previously examined in qualitative research (e.g.[11], [12]). To our knowledge, these results mark the first time that the relationships between mental health-related barriers to exercise and symptoms of anxiety, depression and stress have been quantified. Interestingly, there were moderate negative correlations between the barriers scale and both indicators of social desirability biases: impression management and self-deceptive enhancement. These correlations potentially imply that mental health-related barriers to exercise may be underreported by individuals with higher propensity for social desirability biases.
In sample 2/3, the mental-health related benefits to exercise were negatively correlated with symptoms related to anhedonic depression, symptoms related to general distress – depression, and general distress – mixed, as well as symptoms related to general distress – anxiety to a lesser extent. The results would seem to suggest a stronger relationship between benefits and depressive symptoms than benefits and anxious symptoms, though this was not observed in sample 1. Benefits were again positively correlated with the subjective assessment of physical fitness and PA, as well leisure-time exercise and sport engagement, providing important support for the scale’s convergent validity in physical activity measurement and self-perception. The barriers scale was positively correlated with all measures of affective distress symptoms in sample 2/3, where the MASQ-90 was employed. Thus, for each of the five affective distress subscales, higher levels of symptoms corresponded to higher levels of perceived mental-health barriers. Additionally, in sample 2/3, the barriers scale was negatively associated with leisure-time exercise, as well as subjective fitness and PA. Thus, higher levels of perceived barriers corresponded with lower levels of exercise, and lower levels of perceived fitness and activity.
Some inconsistency between samples was observed. Firstly, the benefits scale correlated significantly with small and negative effects, with nearly all forms of distress in sample 2/3 except anxious arousal. However, in sample 1, the benefits scale showed only small, positive correlations with anxiety and stress and was not correlated with depression. This particular discrepancy may be due to the distributions of scores of the DASS-42 and the MASQ-90 in datasets 1 and 2 respectively. Whilst the DASS-42 subscales each demonstrated bimodal distributions in sample 1, the MASQ-90 subscales each demonstrated positively skewed distributions in sample 2/3. The benefits subscale scores were negatively skewed in both datasets 1 and 2. Thus, there may be a potential effect of the discrepancies in distributions of mental ill health symptoms on the reporting of benefits. Future research may seek to include more homogenous clinical samples for a clearer focus of the relationship between reported benefits and mental ill health symptoms.
Secondly, the barriers scale correlated significantly with moderate and negative effects, with both leisure-time physical activity and with subjective fitness in sample 2/3. However, in sample 1, the barriers scale correlated positively but weakly with self-reported metabolic equivalents (METs) of PA, and with subjective fitness. Indeed, a key difference arises in the measurement of leisure-time exercise specifically in sample 2/3, compared with using overall PA in sample 1. Given that the questions of the MEX scale ask for self-reported attitudes toward leisure-time exercise behaviours and not all physical activity and movement, it is reasonable to consider the leisure-time physical activity scale as a better counterpart to the MEX than the measurement of PA. In consideration of subjective physical activity, it’s worthwhile to note that the distributions of scores differed between datasets. In sample 1, a negatively skewed distribution was observed for subjective physical activity, which coincided with a very low correlation between barriers and subjective activity (r = 0.097). In sample 2/3, an approximately normal distribution was observed and coincided with a moderate correlation between barriers and subjective activity (r = -0.606). Thus, whilst high levels of barriers may be prevalent in individuals who consider their activity and fitness to be low, there may still be a tendency of some individuals to experience higher than expected levels of barriers, despite self-reporting high levels of fitness and physical activity. Such a relationship may be moderated by additional factors, such as affective symptoms, which is a potential area for future exploration.
Finally, an additional inconsistency resulted from the relationship between benefits and barriers was inconsistent across datasets. In sample 2/3, a moderate negative linear relationship was found between MEX barrier and benefit scores. However, a moderate curvilinear association was found in sample 1, whereby low levels of barriers and high levels of barriers were both associated with high levels of benefits, but medium levels of barriers were associated with low levels of benefits. Thus, there appears to be potential variability amongst individuals with high levels of mental-health barriers to exercise. The source of this variability amongst individuals who strongly endorse the barrier items will be an important focus in future research.
Limitations of the present work warrant consideration. Comparison between datasets was made difficult by differences in measurement scales, especially for symptoms of depression, anxiety, and stress, and for leisure-time physical activity. Future research using the MEX in separate samples should therefore use consistent measures of depression, anxiety and stress (i.e. the DASS-42), and leisure-time physical activity (i.e., the LTSES). Additionally, we did not include an objective measure of physical activity. It is important for future work to examine how items on the MEX relate to objective indicators of physical activity, given the typical low reliability found in self-report measures of activity. However, a differentiation may need to be made between leisure-time physical activity and total physical activity in objective measurement. Finally, the sampling was limited to mostly Caucasian, English-speaking participants from western countries, with mostly subclinical depressive and anxious symptoms. Thus, ascertaining norms and factorial invariance for the MEX across diverse socio-cultural samples, and in clinical samples, is an important consideration for future research.