Living a sedentary lifestyle has become a widespread health problem in Western countries, and is one of the causes of chronic diseases such as type 2 diabetes and cardiovascular disease (Lee, Shiroma, Lobelo, Puska, & Blair, 2012). Physical activity has also been inversely associated with mental disorders such as depression (Dunn et al., 2001, Galper et al., 2006 and Lucas et al., 2011), and this association seems to be bi-directional. It has been found that individuals who exercise at least two to three times a week experience significantly less anger, cynical distrust and stress compared to those who exercise less or not at all (Hassmén, Koivula, & Uutela, 2000). Furthermore, a higher sense of coherence and a stronger feeling of social integration has been reported in regard to individuals who exercise at least twice a week in comparison to their less active counterparts (Hassmén et al., 2000). On the other hand, lack of psychological well-being, such as in the form of depression, may also contribute to a sedentary lifestyle and poor adherence to physical activity behaviour (Roshanaei-Moghaddam, Katon, & Russo, 2009).
Mindfulness is a concept that has attracted researcher and practitioner attention worldwide during the last decade (Baer, 2003 and Brown and Ryan, 2003) and has become as an important issue in health promotion and disease prevention research (Greeson, 2009). Mindfulness involves attending to relevant aspects of experience in a non-judgemental manner. In mindfulness training, the goal is to maintain awareness moment by moment, disengaging oneself from beliefs, thoughts, and emotions (Kabat-Zinn, 1982 and Ludwig and Kabat-Zinn, 2008).
A number of studies have evaluated the associations between mindfulness and different health behaviours. Mindfulness skills have been associated with better well-being (Baer, 2003 and Hofmann et al., 2010), healthier eating practices, and better quality of sleep and physical health (Murphy, Mermelstein, Edwards, & Gidycz, 2012). In addition, mindfulness skills have also been recognised as an important element involved in disengaging individuals from their automatic thoughts, habits, and unhealthy behaviour patterns (Baer, Fischer, & Huss, 2005). Furthermore, several studies have shown that greater levels of mindfulness are associated with higher levels of physical activity (Gilbert and Waltz, 2010, Roberts and Danoff-Burg, 2010 and Ulmer et al., 2010). Mindfulness has also been found to moderate the intention–behaviour relationship in the physical activity context in that intentions have predicted leisure-time physical activity in mindful individuals but not among less mindful ones (Chatzisarantis & Hagger, 2007).
Psychological flexibility is another concept that has been recognised as a very important part of purposeful behaviour, dynamically representing well-being and satisfaction in life (Kashdan & Rottenberg, 2010). Psychological flexibility refers to the ability to be in the present moment with full awareness and openness to experiences based on one's own values in life (Harris, 2009 and Hayes et al., 2006). This concept is used especially in Acceptance and Commitment Therapy (ACT), which has been defined as a third wave therapy, having evolved from traditional behaviour therapy and basic behavioural principles ( Hayes et al., 2006). Research evidence has shown that ACT interventions help people to live a more flexible and meaningful life according to their own values, and have been a powerful aid in overcoming many kinds of mental or health-related problems ( Powers, Zum Vörde Sive Vörding, & Emmelkamp, 2009). Besides the evidence from ACT research, little is known about how psychological flexibility is associated with physically active or inactive lifestyles.
The purpose of this study was to compare mindfulness skills, psychological flexibility and psychological symptoms among physically less active and active adults who were recruited and classified based on their self-reported physical activity. Additionally, we evaluated the association of objectively measured physical activity with mindfulness skills, psychological flexibility and psychological symptoms. Based on the available research evidence (e.g., Gilbert and Waltz, 2010, Roberts and Danoff-Burg, 2010 and Ulmer et al., 2010), we hypothesized that physically active adults have better mindfulness skills, greater psychological flexibility, and less psychological and depressive symptoms compared to physically less active adults.
