Summary and research gap on TPB in relation to physical activity
Based on the literature reviewed, the following research gaps can be outlined.
a) Lack of studies using longitudinal design
There are few studies on TPB; in particular, there are a few analysing physical
activity behaviour that employ a longitudinal design. For studies that have used
longitudinal designs, few have analysed intention and behaviour with an intervening
period of more than 1 month (Armitage, 2005). As successful maintenance of
physical activity is typically considered to be an individual’s consistent performance
of a behaviour for at least 6 months (Marcus et al., 2000), studies with longer
interval periods are needed.
Focussing on Malaysia, studies on physical activity behaviour using TPB are limited
and, only one study was identified that used a longitudinal design and measured
actual behaviour. The adoption of the findings of cross-sectional studies as policy is
due to bias from measuring intention and behaviour simultaneously (Armitage,
2005). The present study addresses this limitation with data collection that spans 1
year and four-time points.
b) Lack of studies using TPB to predict future intention and use of indirect
measures
One of the limitations of the previous research on physical activity using TPB is the
lack of prospective measures of behaviour or intention (Armitage, 2005). A large
proportion of studies in the physical activity domain use cross-sectional design which
increases the consistency bias when all variables are measured contemporaneously
(Armitage, 2005). Another concern is that whenever a prospective design is used, the
interval between assessment of TPB variables and subsequent measure of intention
or behaviour is short and does not exceed 1 month (Armitage, 2005; Randall & Wolff,
1994). Given that physical activity should be performed consistently and the health
benefits associated with it take some time to accrue, prospective designs that span
longer than a month are required. To address this issue, the present study includes
prospective examination of intention to perform physical activity. In this examination,
the independent variables of attitude, PBC and SN were used to predict the intention
at the next time point. Another strength of the present study was that it included
indirect measures of the TPB constructs.
c) Lack of qualitative studies using TPB
Studies adopting the TPB with qualitative methods are not common (Renzi & Klobas,
2008). The methods developed for data collection and analysis with TPB are mostly
quantitative with qualitative studies suggested for elicitation studies only (Ajzen, n.d.;
Renzi & Klobas, 2008). Qualitative methods have their advantages compared to
quantitative methods as they describe in greater detail the meaning of a
phenomenon. To address this limitation, the present study employed a mixed
methods approach with three qualitative studies and four time points of quantitative
questionnaire data collection.
Definition of Quality of Life and Related Concept
This section discusses quality of life and studies on quality of life in relation to physical
activity and quality of life in relation to physical activity in Malaysia. The research gaps
are identified at Section 2.5.3.
Quality of life is a complex and multifaceted construct that requires multiple approaches
from different theoretical angles (Theofilou, 2013). The definition of quality of life varies
in the literature: some definitions focussed on individuals’ perception of their health
status and some focussed on individuals’ level of satisfaction with their health status
(Blake, 2012). A commonly cited definition for quality of life is a state of well-being that
is a composite of two components: the ability to perform everyday activities that reflect
physical, psychological and social well-being; and patient satisfaction with the level of
functioning and control of disease and/or treatment-related symptoms (Blake, 2012).
Literature searches on quality of life and its association with physical activity revealed a
wide range of studies exploring multiple related concepts including subjective well-
being, psychological well-being, satisfaction with life, affect, self-esteem, enjoyment,
sense of coherence and happiness.
Assessment of quality of life has increased in recent years (Poole, Murphy, & Nurmikko,
2009) and there are a number of challenges to developing a meaningful understanding
of quality of life and well-being (Theofilou, 2013). Quality of life is difficult to measure
and define as it encompasses a multidimensional concept that emphasises the self-
perception of an individual’s current state of mind (Bonomi, Patrick, Bushnell, & Martin,
2000).
Quality of life includes individual’s evaluation of all aspects of life including factors such
as safety of the environment in which they live, whether they feel they have access to
health care and social services as well as their current spiritual status (Bonomi et al.,
2000). The WHOQOL defined quality of life as individuals’ perception of their position in
life in the context of the culture and value system in which they live and in relation to
their goals, expectations, standards and concerns (Bonomi et al., 2000). Despite this
definition by the WHOQOL Group, there is still no consensus on the definition of quality
of life (Bonomi et al., 2000; WHOQOL Group, 1995) but there is considerable
agreement among experts that the characteristics of quality of life are subjective, multi-
dimensional and include both positive and negative dimensions (WHOQOL Group,
1995).
Subjective well-being is a broad category of phenomena that includes people’s
emotional response, domain satisfaction and global judgement of satisfaction (Diener,
Suh, Lucas, & Smith, 1999). For the subjective features of quality of life, the WHOQOL
Group (1995) proposed three levels of questioning: the first area are information about
functioning (e.g. how many hours of sleep did you get last night?), global evaluation of
functioning (e.g. how well do you sleep?) and highly personalised evaluation of
functioning (How satisfied are you with your sleep?). The second area of consensus is
the multi-dimensional nature of quality of life. It was proposed that quality of life includes
physical, psychological, social and spiritual dimensions (WHOQOL Group, 1995). The
third area of understanding is that quality of life includes both positive and negative
dimensions. Studies into quality of life must include positive dimensions such as role
functioning, contentment and mobility and negative dimensions such as dependence on
medication, fatigue and pain (WHOQOL Group, 1995)
The WHO organised their quality of life measure (WHOQOL) into six broad domains:
physical, psychological, level of independence, social relationship, environment and
spirituality (WHOQOL Group, 1995). The WHO Quality of Life instrument assesses an
individual’s perception of their position in life in the context of the culture and value
system in which they live in relation to their goals, standards, expectation and concerns
(WHO, 1998). The WHOQOL-BREF is the shorter version of the assessment instrument
which comprises four domains with 24 facets relating to quality of life (WHO, 1998). The
four domains of the WHOQOL-BREF are physical health, psychological, social
relationship and environment. (For a detailed discussion about the instrument, please
refer to Chapter 4 – Instrumentation Development).
Quality of life and physical activity
A large body of literature on the relationship between physical activity and mental health
conditions using cross-sectional designs showed that non-exercisers are characterised
by anxiety and depression (Stubbe et al., 2007). Evidence through randomised control
trials also showed that exercise acutely reduces the feelings of tension, anxiety and
anger as well as increasing the feeling of vigour (Stubbe et al., 2007). Exercise is a sub-
group of leisure behaviour and there is a general consensus that participation in
exercise is linked to higher levels of well-being (Sylvester et al., 2014). The experience
of well-being has been consistently found to result in a range of positive and adaptive
responses among adults, such as more fulfilling relationships or longer and healthier
lives (Sylvester et al., 2014).
A study on the effect of aerobic exercise on quality of life among patients with
hypertension in Nigeria was carried out by Maruf, Akinpelu, and Salako (2013). In this
12-week randomised control trials study, participants were recruited from patients newly
diagnosed with mild to moderate hypertension who were randomly assigned to
antihypertensive drugs or on exercise + drugs group. The results showed that physical
health, psychological and social relationship domains improved significantly in the both
groups post-intervention. The environmental domain and exercise capacity improved on
exercise + drug group. Findings indicated that with aerobic exercise, the patients with
hypertension experienced wider quality of life domain improvement compared to drug-
only patients.
Quality of life and physical activity among elderly individuals in Indonesia was assessed
by Kusumaratna (2008). The study involved 21 males and 80 females older than 60
years (mean age = 66.4 years) and participants were classified into low, moderate and
highly active groups. The overall quality of life scores on all four domains were
significantly higher in the group reporting higher level of physical activity.
Group physical activity was used to improve the quality of life among patients with a
depressive disorder. A study to compare quality of life over 32 weeks with depressed
women using anti-depressant drug + exercise and without exercise was conducted by
Carta et al. (2008). Female participants aged between 40 and 60 years with a diagnosis
of major depressive disorder resistant to ongoing treatment were recruited for the study
from a psychiatric unit. Data were collected using WHOQOL-BREF at eight time points
(Time 1 to Time 8) during the study period. The results indicated that the quality of life
for physical domain among patients with physical activity and drug treatment recorded
significant improvement from baseline to Time 8. By contrast, no significant
improvement in the physical domain was reported in the control group without exercise
regime. Both exercise and control group did not report significant differences in other
domains of quality of life. The study provides support for the view that physical activity
could potentially improve the physical domain of quality of life among patients with
depressive disorder.
The literature reviewed so far corroborates the findings of Bize, Johnson, and Plotnikoff
(2007) that studies on health-related quality of life have (HRQOL) not really focussed
on the general population and have been predominantly concerned with clinical
populations or the elderly population. The following discussion considers data from
selected studies on quality of life in general populations.
A systematic review to examine physical activity in the “no clinical condition” general
population and HRQOL was carried out by Bize et al. (2007). Eligible studies included
in this review were those exploring HRQOL in relation to physical activity among the
general population. Participants consisted of healthy adults aged 15 or older, studies
specifically targeting older adults aged 65 years and above were excluded. This review
accessed electronic databases in two phases for papers published from 1966 until
2007. From the searches, 1426 papers were retrieved and after a screening process by
two independent assessors, only 14 papers were included in the final review. Of the 14
papers, 7 were cross-sectional studies, 2 cohort studies, 4 randomised control trials
and 1 mixed cross-sectional and longitudinal study. The inclusion criteria for papers
were studies on HRQOL in relation to physical activity in the general population and not
specific clinical populations with specific chronic illness. Reviews from five cross-
sectional studies showed that all reported significant statistical associations of physical
activity and physical functioning: four with vitality, three with general health domain and
one with mental health and role-physical domain. The support provided for the
relationship between HRQOL from results based on cohort and randomised control
trials studies was, however, weak. Studies from these two designs found differences in
scores for HRQOL according to group allocation or physical activity level.
A study on the association between physical activity and quality of life among
population-based adults who were not included in the systematic review by Bize et al.
(2007) was conducted by Pucci et al. (2011). The study was carried out on 1,461 adults
between the ages of 18 and 65 years living in Curitiba, Brazil. The quality of life was
assessed using the WHOQOL questionnaire and physical activity using IPAQ. The
results showed a positive association between physical activity and quality of life with a
different relationship for men and women. For men, walking for leisure was associated
with social relationships (β = 1.5, p = .011) and environment (β = 3.3, p = .015).
Moderate intensity was associated with physical (β = .30, p
= .016) and psychological (β = 2.9, p = .003) domains while vigorous intensity was
related to only the physical (β = 1.8, p = .028) domain. For women, walking was
reported to have a significant association between quality of life and physical (β = 3.2, p
= .045) and environment (β = 4.1, p = .011) domains while moderate intensity had
relationship between quality of life and social relationships (β = 4.6, p = .037) and
environment (β = 6.1, p = .01) domains. In conclusion, the findings showed a positive
relationship between physical activity and quality of life.
