Exercise and Quality of Life

Quality of life (QOL) assessments are instrumental in  developing  a  more  comprehensive  understanding of the efficacy of disease prevention and health promotion  interventions.  There  is  growing  interest  in  delineating  the  role  of  exercise  in  enhancing QOL outcomes. Indeed, findings from multiple reviews  on  the  effect  of  exercise  on  QOL  reveal that exercise consistently results in small to moderate,  yet  clinically  meaningful,  improvements  in multiple QOL outcomes, ranging from global indices of life satisfaction to disease-specific measures of  QOL  dimensions.  Collectively,  these  findings provide compelling evidence of the QOL benefits of exercise across a variety of populations.

Given  the  well-established  QOL  benefits  of exercise,  determining  factors  that  influence  the exercise–QOL relationship is a focal point of contemporary exercise psychology research. Therefore, among the objectives of this entry are to identify: (a)  considerations  in  the  conceptualization  and structure  of  QOL  and  (b)  potential  moderators and mediators of the exercise–QOL relationship.

Definition and Structure of Quality of Life

Definitions  of  QOL  vary  across  studies  examining  the  exercise–QOL  relationship.  In  the  psychology  literature,  QOL  is  conceptualized  as  an index   of   overall   life   satisfaction.   Conversely, medical  and  behavioral  science  disciplines  have espoused  multidimensional  perspectives  of  QOL outcomes  reflecting  one’s  appraisal  of  key  life components including physical health, psychological  well-being,  social  relationships,  and  level  of independence.  In  select  medical  disciplines,  QOL is  conceptualized  as  health-related  quality  of  life (HRQOL),  a  multidimensional,  umbrella  concept that comprises broad categories of well-being and functioning  and  more  discrete,  specific  aspects reflecting  core  dimensions  of  function  and  wellbeing.  Subjective  well-being  (SWB),  a  related  yet distinct  outcome,  is  comprised  of  life  satisfaction (the cognitive evaluation of the overall quality of one’s life) and positive and negative affect (the frequency  and  intensity  of  pleasant  and  unpleasant feelings experienced in one’s life).

Variability  in  the  conceptualization  of  QOL across  disciplines  presents  a  challenge  to  synthesizing  knowledge  of  the  QOL  benefits  of  exercise. Nonetheless, it can be concluded that QOL, HRQOL,  and  SWB  are  related,  though  not  isomorphic, constructs and that exercise consistently elicits  improvements  of  similar  magnitude  across these  outcomes.  Emerging  evidence  also  suggests that  QOL  outcomes  are  hierarchically  organized and  exercise-related  improvements  in  proximal QOL  subdomains  predict  favorable  change  in more distal global QOL outcomes. Consistent with this proposed hierarchical structure, QOL can be viewed as an umbrella term involving the subjective  appraisal  of  various  dimensions  of  one’s  life, encompassing  global  ratings  of  life  satisfaction, broad  dimensions  of  functioning  and  well-being, and perceptions of specific domains of functioning and well-being.

Moderators and Mediators of the Effects of Exercise on Quality of Life

With regard to moderator variables, baseline QOL values  consistently  act  as  independent  predictors of improvements in QOL following exercise across multiple  population  subgroups  and  QOL  outcomes. These findings provide compelling evidence for the position that those who have the most to gain in terms of improvement of QOL (e.g., those presenting  with  the  least  favorable  QOL  profile at  baseline)  prior  to  initiating  exercise  derive  the greatest benefit from exercise interventions across an array of QOL outcomes. Although gender has been proposed to moderate the effects of exercise on QOL, evidence of consistent gender differences in  the  QOL  responses  to  exercise  interventions remains equivocal and warrants further inquiry.

Investigations addressing mediators of the QOL benefits  of  exercise  have  adopted  top-down  or bottom-up  perspectives.  Top-down  perspectives propose that judgments of satisfaction with specific domains of life, functioning, and/or well-being are determined  by  ratings  of  overall  QOL  and  wellbeing.  Thus,  those  reporting  favorable  ratings  of global  life  satisfaction  or  well-being  evaluate  specific dimensions of life in a similarly positive manner.  Conversely,  bottom-up  perspectives  propose that  judgments  of  specific  life  domains  influence global  ratings  of  QOL.  Although  both  top-down and  bottom-up  models  have  merit,  findings  from the exercise–QOL literature have yielded consistent support  for  the  bottom-up  perspective  and  little evidence of the utility of the top-down approach.

Consistent  with  the  bottom-up  perspective, recent  studies  in  multiple  sclerosis  patients  demonstrated  that  exercise  positively  influenced  self-efficacy, disease symptoms, and select indicants of psychological well-being. In turn, changes in these intermediate  outcomes  were  linked  with  more favorable  ratings  of  global  QOL.  Similar  mediational pathways were observed with exercise interventions  targeting  arthritis  patients.  For  example, mobility-related self-efficacy beliefs and knee pain symptoms,  both  domain-specific  QOL  measures, mediated the beneficial effect of exercise upon functional performance and ratings of generic HRQOL.

Additionally,  satisfaction  with  physical  function,   knee   pain   ratings,   and   mobility-related self-efficacy  has  been  identified  as  independent mediators  of  the  effect  an  exercise  and  dietary interventions on QOL in arthritis patients. Studies also  demonstrated  that  the  favorable  effects  of exercise  on  global  QOL  were  partially  mediated by  improvements  in  affective  responses,  self-efficacy, and perceptions of social support among older adults at risk for functional decline.

Thus,  the  effects  of  exercise  on  global  indices of QOL can be mediated by changes in proximal QOL domains. The indirect effect of exercise upon global  QOL  suggests  that  these  potential  mediators  should  be  targeted  within  future  exercise intervention trials. It also provides support for the hierarchical structure of QOL outcomes whereby improvements  in  proximal  QOL  constructs  lead to improvements in distal global QOL outcomes. Thus,   exercise   may   influence   proximal   QOL dimensions  assessed  by  measures  of  generic  core domains of QOL and disease or population-specific symptoms. In turn, favorable changes in these proximal QOL outcomes subsequently contribute to improvements in overall, global ratings of QOL.

Directions for Research in the Exercise–Quality of Life Relationship

Select  areas  of  future  inquiry  may  be  particularly integral  to  advancing  knowledge  of  the  exercise– QOL  relationship.  It  is  critical  for  researchers  to acknowledge  that  QOL,  HRQOL,  and  SWB  represent related yet conceptually distinct constructs. Additionally, emerging evidence supports the position  that  QOL  outcomes  are  hierarchically  organized and that a bottom-up model accounts for the direct effects of exercise on QOL domain outcomes and indirect effects upon global QOL.

Implementation  of  a  hierarchical,  bottom-up conceptualization  of  the  exercise–QOL  relationship  has  important  implications  for  designing exercise interventions. This approach suggests that multilevel  assessments  integrating  global  indices of life satisfaction, generic measures of QOL, and targeted measures of domain-level QOL outcomes should be included as a standard part of theoretically driven assessment batteries. Augmenting this approach  through  the  measurement  of  conceptually  relevant  and  evidence-based  mediators  will also  expand  understanding  of  the  mechanisms underlying the QOL benefits of exercise. Adoption of the hierarchical model could have ancillary benefits in advancing knowledge of the role of exercise in enhancing QOL. For example, exercise-induced increases in specific QOL domains are mistakenly interpreted  as  reflecting  improvement  in  other  QOL  domains  or  global  QOL.  In  a  hierarchical model  of  QOL,  improvements  in  QOL  domains should  not  be  assumed  to  be  indicants  of  change in global QOL. Consequently, improvement in one QOL measure should not be used as a proxy for inferring change in different QOL outcomes.

In  summary,  exercise  is  valuable  for  enhancing and  sustaining  QOL.  Despite  the  well-established QOL benefits of exercise, advances in the conceptualization of QOL outcomes and the mechanisms underlying  improvements  in  QOL  have  been  limited. Adopting a hierarchical, bottom-up approach to  the  study  of  exercise-related  QOL  benefits  is an  important  step  in  augmenting  the  incremental progress that has been observed in the investigation of the exercise–QOL relationship.

References:

  1. Berger, B. G., & Tobar, D. A. (2007). Physical activity and quality of life: Key considerations. In G. Tenenbaum & R. C. Eklund (Eds.), Handbook of sport psychology (3rd ed., pp. 598–620). Hoboken, NJ: Wiley.
  2. Focht, B. C. (2012). Exercise and health-related quality of life. In E. O. Acevedo (Ed.), The handbook of exercise psychology (pp. 97–116). New York: Oxford University Press.
  3. Motl, R. W., & McAuley, E. (2010). Physical activity, disability, and quality of life in older adults. Physical Medicine and Rehabilitation Clinics of North America, 21, 299–308.

 

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