Wurm et al., 2010

7/21/2019 Wurm et al., 2010

1/19

PLEASE SCROLL DOWN FOR ARTICLE

This article was downloaded by: [Wurm, Susanne]

On: 30 August 2010

Access details: Access Details: [subscription number 918818632]

Publisher Routledge

Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-

41 Mortimer Street, London W1T 3JH, UK

Psychology Health

Publication details, including instructions for authors and subscription information:http://www.informaworld.com/smpp/title~content=t713648133

On the importance of a positive view on ageing for physical exercise

among middle-aged and older adults: Cross-sectional and longitudinal

findings

Susanne Wurma; Martin J. Tomasikb; Clemens Tesch-RmeraaDeutsches Zentrum fr Altersfragen, Berlin 12101, Germany bFriedrich-Schiller-University, Jena07743, Germany

First published on: 04 November 2008

To cite this ArticleWurm, Susanne , Tomasik, Martin J. and Tesch-Rmer, Clemens(2010) 'On the importance of a positiveview on ageing for physical exercise among middle-aged and older adults: Cross-sectional and longitudinal findings',Psychology & Health, 25: 1, 25 42, First published on: 04 November 2008 (iFirst)

To link to this Article: DOI:

10.1080/08870440802311314

URL: http://dx.doi.org/10.1080/08870440802311314

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf

This article may be used for research, teaching and private study purposes. Any substantial orsystematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply ordistribution in any form to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae and drug dosesshould be independently verified with primary sources. The publisher shall not be liable for any loss,actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly

or indirectly in connection with or arising out of the use of this material.
http://www.informaworld.com/smpp/title~content=t713648133http://dx.doi.org/10.1080/08870440802311314http://www.informaworld.com/terms-and-conditions-of-access.pdfhttp://www.informaworld.com/terms-and-conditions-of-access.pdfhttp://dx.doi.org/10.1080/08870440802311314http://www.informaworld.com/smpp/title~content=t713648133

7/21/2019 Wurm et al., 2010

2/19

Psychology and Health

Vol. 25, No. 1, January 2010, 2542

On the importance of a positive view on ageing for physical

exercise among middle-aged and older adults: Cross-sectional

and longitudinal findings

Susanne Wurma*, Martin J. Tomasikb and Clemens Tesch-Ro mera

aDeutsches Zentrum fur Altersfragen, Manfred-von-Richthofen Str. 2, Berlin 12101, Germany;bFriedrich-Schiller-University, Am Steiger 3/1, Jena 07743, Germany

(Received 19 January 2007; final version received 20 January 2008)

Physical activity is one of the most important health behaviours associated withthe prevention and management of chronic diseases in older adults, but thispotential is often insufficiently used. The present study examined for the first timewhether a positive view on ageing (PVA) may contribute to a higher level ofphysical activity. Analyses were based on the German Ageing Survey, alongitudinal population-based survey (N 4034) on middle-aged and olderadults (4085 years) conducted in the years 1996 and 2002. As hypothesised,middle-aged adults with a PVA not only engaged in physical activity in the formof sports more frequently; they even increased this activity provided that theywere healthy enough to do so. For older adults, PVA was particularly associatedwith more regular walking and increases of walking over time. Because walking isoften still recommended in spite of health problems, it was remarkable that evenolder people with worse health walked just as regularly as those with good health,provided that they had a positive view on ageing. The results shed some light onrecent findings about the importance of PVA for health and longevity and pointto a partial mediation between PVA and health by physical exercise.

Keywords: positive view on ageing; physical activity; exercise; health; longitudinalsurvey

Introduction

Physical activity continues to be a key factor for the prevention and management of many

risk factors, chronic diseases and functional disabilities associated with ageing up to old

age (e.g. Blumenthal & Gullette, 2002; Paterson, Govindasamy, Vidmar, Cunningham, &Koval, 2004). Moreover, physical activity may lead to a shorter period of disability at the

end of life (Hubert, Bloch, & Oehlert, 2002) and to a lower risk of premature mortality,

even in the case of activities of low or moderate intensity (Fried et al., 1998; Landi et al.,

2004; Paffenbarger et al., 1994). However, a large number of people remain sedentary.

Already from early adulthood this portion grows steadily, meaning that older persons are

the most sedentary segment of the adult population (European Opinion Research Group

EEIG, 2003; U.S. Department of Health and Human Services, 1996). In contrast to

*Corresponding author. Email: [email protected]

ISSN 08870446 print/ISSN 14768321 online

2010 Taylor & Francis

DOI: 10.1080/08870440802311314

http://www.informaworld.com

7/21/2019 Wurm et al., 2010

3/19

younger people, who often name lack of time as a main cause for a sedentary lifestyle,

older people often report health problems as the main barrier to physical exercise (for a

review: Schutzer & Graves, 2004).

Both moderate and vigorous exercise is favoured in physical activity recommendations

(e.g. World Health Organization, 1997). Because middle-aged adults have both fewer

health problems and higher physical activity than older adults, recommendations for

middle-aged adults usually refer to activities with higher energy expenditure; these are

particularly important for weight regulation and cardiovascular health. Although, these

health goals are also important for older adults (e.g. Goldberg & King, 2007), moderate

physical activities have the highest priority in the recommendations for older age groups.

This is due both to the high prevalence of a sedentary lifestyle and to a higher prevalence

of chronic diseases and disabilities (DiPietro, 2001). Even moderate physical activity can

yield important health benefits for maintaining functional ability and independence

(DiPietro, 2001). By contrast, vigorous physical activities such as fast cycling or tennis are

not always indicated for individuals with cardiovascular or musculoskeletal disorders, in

particular if these are caused by decades of sedentary living habits and a progressive loss ofmusculoskeletal function (Blair, Kohl, Gordon, & Paffenbarger, 1992).

Since it has been shown that health behaviour is beneficial up to old age, there is

growing interest not only in the determinants of physical exercise for younger age groups

but for older people as well (Morley & Flaherty, 2002). Population-based studies indicate

that demographic variables such as gender (with less physical exercise among women),

socio-economic status and education (with less physical exercise among people with lower

educational levels, or incomes), and social support by friends or spouses influence the

prevalence of physical exercise throughout the lifespan (e.g. DiPietro, 2001).

Moreover, mechanisms of self-regulation, such as goal setting, self-monitoring and

relapse-prevention training and in particular functional optimism (which includes bothpositive outcome expectancies and self-efficacy beliefs; Schwarzer, 1994), have been shown

to be important psychological factors for the adoption and maintenance of physical

exercise. Most of these findings were based on intervention studies (e.g. King, 2001;

McAuley, Jerome, Elavsky, Marquez, & Ramsey, 2003), while large population-based

surveys rarely examine psychological factors (Newsom, Kaplan, Huguet, & McFarland,

2004). However, people who take part in an intervention programme generally already

possess a basic motivation for health behaviour change, that is, these people are at least in

a contemplation stage (Prochaska & Velicer, 1997) and thus differ from the general

population. We, therefore, still know little about psychological factors involved in the

promotion of regular exercise among older adults in everyday life, apart from interventionprogrammes (e.g. Lachman et al., 1997). What is it then that motivates older people to be

physically active or even to increase their activity, independent of intervention

programmes? The purpose of the present study is to address one of these possible

motivators by examining whether a positive view on ageing (PVA) might promote physical

exercise; this is explained in more detail below.

In recent years, several longitudinal studies have shown that older people who have a

more PVA maintain better physical and functional health than those with a more negative

view (Levy, Slade, & Kasl, 2002; Wurm, Tesch-Ro mer, & Tomasik, 2007). Moreover,

a PVA has repeatedly been shown to be an important determinant for longevity (e.g.

Levy & Myers, 2005). The underlying mechanisms that make a PVA a health protectivefactor have barely been empirically examined. However, one recent study indicates

that a PVA may in fact contribute substantially to general preventive health behaviour

26 S. Wurmet al.

7/21/2019 Wurm et al., 2010

4/19

(Levy & Myers, 2004), and therefore suggests that analysing this association with respect

to physical exercise is worthwhile.

In the present study, a PVA refers to the view that ageing is accompanied by further

developmental gains. A gain-related view on ageing cannot be taken for granted because

younger as well as older individuals tend to view ageing as accompanied by a decrease in

gains and an increase in losses (Heckhausen, Dixon, & Baltes, 1989). Regarding ageing asaccompanied by further gains implies that the personal future still has a positive meaning

and that a person continues to perceive an ample time frame in his or her life for setting

goals and making plans. Having goals and a positive future outlook might make it worth

engaging in health behaviour such as physical exercise because the pursuit of certain goals

(e.g. improving skills, caring for grandchildren) requires sufficiently good health. Thus,

people with a PVA are presumably more motivated to engage in preventive health

behaviour such as physical exercise because they experience that it is still worth doing

something for their own health.

By contrast, a less positive view on ageing, which includes a shorter subjective time

perspective and a stronger focus on the present, might prevent beneficial health behaviourbecause the consequences of this behaviour lie behind the individually perceived time

horizon (Rakowski, 1986). It is known that, even in the case of young adults, a short-time

perspective focusing on the present is negatively associated with healthy behavioural

practices (Hall & Fong, 2003). For older people, whose lifetime is more limited, it is even

harder to maintain a strong positive future outlook and to believe in the future benefits of

positive health behaviour.

The present study investigates the importance of a PVA for physical activity in middle

and later adulthood. Are people who view their ageing in a positive way physically more

active than those with a less positive view on their ageing process? And does this

association still persist when the socio-demographic, socio-economic and psychologicalvariables important for physical exercise are controlled for in the analyses?

Ageing comes with increasing physical and social losses, and middle age seems to be the

turning point in the ratio of gains and losses (Baltes, Lindenberger, & Staudinger, 1998).

In line with this turning point, we included in the present study people as from midlife. The

analysis of both middle-aged and older adults goes beyond comparable previous studies on

physical activity in later adulthood that have primarily focused on people aged 60 or 65

years and above (e.g. Burton, Shapiro, & German, 1999; McAuley et al., 2003). Studies on

physical activity of older adults have often examined low to moderate-intensity physical

activity such as walking, stair climbing or housework (e.g. Newsom et al., 2004) and

therefore have allowed for the fact that the vast majority of older people do not engage in

sporting activity. Due to the broadening of the perspective to middle-aged adults in the

present study, we considered not only moderate exercise (i.e. walking) but sporting activity

as well. Walking ranks more among the light to moderate activities and can usually be

performed despite chronic diseases and disabilities (DiPietro, 2001). Sporting activities,

however, predominantly rank among moderate to vigorous activities and thus require a

sufficiently good state of health (cf. Blair et al., 1992). In the present study, we included

both walking and sporting activities as outcome variables in order to analyse a broad

range of physical activities. However, these two indicators probably have a different

validity for the different age groups. Walking may not be an adequate indicator for

strenuous physical activity in middle-aged adults and sporting activities are likely to

overburden the physical capacities of many in old age. In the following hypotheses we thusexpected more distinct results for middle-aged adults with regard to sporting activities and

for old-aged adults with regard to walking.

Psychology and Health 27

7/21/2019 Wurm et al., 2010

5/19

Generally, we expected that a PVA would contribute to overcoming motivational

barriers to physical activity. More specifically, we hypothesised on a cross-sectional level

of analysis that a PVA would be related to higher physical activity (Hypothesis 1). Based

on the fact that physical activity declines with increasing age, we hypothesised on a

longitudinal level of analysis that a PVA would prevent a strong decrease in physical

activity; that is, we expected individuals with a more PVA to have a lower decrease in their

physical activity over time (Hypothesis 2). Finally, we expected a PVA to contribute

particularly to a lower decrease or even stability of physical activity should individual

health status so allow. For the cross-sectional and the longitudinal model, we therefore

additionally tested whether health serves as a moderator of a PVA in the prediction of

physical activity (Hypothesis 3).

Method

Participants and procedure

The analyses were based on data of the German Ageing Survey. This survey is an

ongoing nationwide and population-based study on middle-aged and older adults

(cf. Engstler & Wurm, 2006). First, the baseline sample(age 40 to 85 years) was drawn in

1996 by means of a national probability sampling technique with stratified sampling by

age, gender, and place of residence (Eastern or Western Germany). About 50% of the

persons contacted agreed to an interview (N 4838) and 83.4% of them additionally

completed a questionnaire (N 4034). The response rate corresponds to that of other

large survey studies in Germany (Neller, 2005). In the present study we used data

assessed within the questionnaire, which is why we only refer to the sample ofN 4034.

This baseline sample was on average 60.1 years old, 49% (n 2065) of whom were

women and 66% (n 2668) lived in Western Germany. Detailed sample characteristics

are shown in Table 1, broken down in the groups of middle-aged (4064 years) and older

adults (6585 years). The age limits correspond to a common distinction between middle

adulthood and third age (e.g. Schaie & Willis, 2002) and, furthermore, reflects the legal

transition age into retirement. All analyses were computed for both age groups

separately because middle-aged and older adults differ considerably in their physical

activity. According to the baseline sample (N 4034), middle-aged adults reported

higher sporting activity (t(4032) 11.86, p50.001) and lower frequency of walking

(t(4032) 8.56, p50.001) than older adults.

Second, in 1996 the participants of the baseline sample were asked whether they were

willing in principle to participate again at a later point of time and 61% ( N 2972) agreedto this. The addresses of the other participants were deleted in accordance with the

regulations of the German data protection law. Six years after the first interview, 16.3% of

the 2972 respondents had died or moved to unknown addresses, which reduced the sample

that could be contacted for a second time to N 2478. A total of 63.8% of persons from

this reduced sample were in fact re-interviewed, while 36.2% refused (due to illness, or

without giving any reason). Considering again only those people who completed both

interview and questionnaire, the longitudinal sample consisted of N 1286 participants.

Compared to the baseline sample, the longitudinal sample was about 3 years younger

(MAgeT1 57.07; SD 10.81), but hardly differed in gender (52% male; n 675) and the

place of residence (63% from Western Germany; n 816).Independent sample t-tests were computed to assess the differences in the baseline

scores between participants of the longitudinal sample and those who dropped out after

28 S. Wurmet al.

7/21/2019 Wurm et al., 2010

6/19

the first interview. Both groups differed significantly (p50.01) in all variables described

in Table 1, except for gender, place of residence and frequency of walking. On average,follow-up participants had higher socio-economic status (education, income, prestige),

more often a partner, and rated their health better. Moreover, follow-up participants

had significantly higher optimism (hope), a more PVA and higher sporting activity. As

can be seen in Table 1, the selective attrition applies more to the older adult group than

to middle-aged adults. This reflects the established fact of selective attrition in

longitudinal research on ageing (e.g. Baltes, Schaie, & Nardi, 1971; Norris, 1985). We

get back to the implications of sample selectivity in the discussion section.

Measures

Physical exercise

Participants were asked for their frequency of walking and doing sports (How often do

you go for walks?; How often do you do sports, i.e. hiking, football, callisthenics or

swimming?). Both questions could be answered on a 6-point scale ranging from never to

daily. The two variables on physical exercise were the only variables assessed at two

measurement occasions while all other variables pertain to the first measurement occasion

only (cf. Table 1).

Positive view on ageing (PVA)In order to assess a PVA we used a scale on the ageing-related cognition of ongoing

development; this scale has been shown to be important for physical health over time

Table 1. Sample characteristics: percent or means and standard deviations (in brackets).

Baseline sample (N 4034) Longitudinal sample (N 1286)

Middle-aged(4064 years;

n 2544)

Older adults(6585 years;

n 1490)

Middle-aged(4064 years;

n 956)

Older adults(6585 years;

n330)

Age (years) 52.2 (7.10) 72.55 (5.85) 51.98 (6.98) 71.80 (4.72)Female 48.9% 48.7% 48.4% 44.8%Western Germany 66.2% 66.1% 63.5% 63.3%Education 1.58 (0.74) 1.32 (0.63) 1.70 (0.78) 1.48 (0.70)Income (EUR) 1302.02 (752.87) 1140.52 (677.68) 1363.94 (754.30) 1251.51 (620.39)Prestige 46.78 (11.75) 44.40 (11.21) 48.74 (11.86) 47.78 (11.89)Living with partner 86.4% 64.9% 87.7% 72.7%Physical health 7.92 (1.68) 6.61 (1.96) 7.96 (1.63) 6.88 (1.93)PVAa,b 0.66 (0.61) 0.18 (0.72) 0.08 (0.56) 0.23 (0.67)Hopeb 1.11 (0.99) 0.95 (1.08) 0.01 (0.95) 0.02 (0.97)

Sports T1 1.78 (1.67) 1.13 (1.70) 2.00 (1.70) 1.47 (1.74)Sports T2 1.98 (1.72) 1.39 (1.81)Walking T1 3.01 (1.52) 3.48 (1.73) 2.99 (1.51) 3.62 (1.64)Walking T2 3.16 (1.59) 3.28 (1.72)

Notes: All data refer to the first wave of the survey (T1) unless otherwise noted. Education: 1 low,3high. Prestige: 18.1 low, 78.9high. Physical Health: 0 low, 10high; see sectionMeasures.aPositive View on Ageing; bLatent variable scores.


7/21/2019 Wurm et al., 2010

7/19

(Wurm et al., 2007). The scale refers to the view of ageing as a time of personal growth and

development and was assessed by the four items Ageing means to me that I continue to

make plans, Ageing means to me that my capabilities are increasing, Ageing means to

me that I can still learn new things, and Ageing means to me that I can still put my ideas

into practice. Item wordings and scale development originate from Dittmann-Kohli and

her colleagues (e.g. Steverink, Westerhof, Bode, & Dittmann-Kohli, 2001). Participants

could endorse the items on a 4-point scale ranging from definitely false to definitely true.

In the present study, the scale itself was obtained by calculating the latent variable score

from a congeneric measurement model with two error terms allowed to correlate. This

model fitted the data very well both at baseline (2(1) 1.96, p 0.16, RMSEA 0.015,

NNFI 1.00, SRMR 0.003) and the longitudinal sample (2(1) 0.92, p 0.34,

RMSEA 0.000, NNFI 1.00, SRMR 0.004). In the baseline sample, the factor

loadings ranged between 0.52 and 0.78 (longitudinal sample: 0.430.77) resulting in a

reliability of 0.74 (longitudinal sample: 0.67) according to Raykov (2004).

Physical health

Respondents reported whether they had any of the 11 health problems in question (e.g.

cardiovascular diseases, circulatory problems, back or joint diseases, diabetes, gastro-

intestinal diseases, respiratory diseases). For each person we counted a sum score based on

the absolute number of reported illnesses. We recoded this score subsequently so that a

high score means a low morbidity and scores near to zero mean that a person has a high

number of coexistent diseases (multimorbidity). The sum score was chosen due to the lack

of medical checkups and to various advantages compared to single self-reported illnesses.

Katz and colleagues (Katz, Chang, Sangha, Fossel, & Bates, 1996) have shown that the

best accordance between medical reports and self-reports are achieved when summary

scores are used. Moreover, global scores of self-reported illnesses are considered as better

proxies for (at least some) functional disability compared to single illnesses (Neugarten,

1996). Due to the large age range of the sample (4085 years) we did not use an indicator

that directly assesses functional disability because the vast majority of persons reported no

general functional limitation.

Hope

The Dispositional Hope Scale (8 items; Snyder et al., 1991) was used to assess functionaloptimism and served as a control variable in the following analyses. According to Snyder

and colleagues, hope is fuelled by the expectation of successful outcomes (agency facet;

e.g. I energetically pursue my goals) and self-efficacy (pathways facet; e.g. I can think of

many ways to get out of a jam). The items could be answered on a 4-point scale ranging

from definitely false to definitively true. A latent measurement model was set up in

order to compute the latent variable scores (baseline: 2 (2) 11.83, p 0.003,

RMSEA 0.035, NNFI 1.00, SRMR 0.006; longitudinal sample: 2 (2) 0.91,

p 0.63, RMSEA 0.000, NNFI 1.00, SRMR 0.003). Scale reliability was computed

according to Raykov (2004) and was found to be satisfactory in the baseline ( 0.87),

and longitudinal sample (

0.86). The Hope scale was correlated with PVA to a mediumextent (r 0.53 in the baseline sample andr 0.46 in the longitudinal sample; cf. Table 2),

which makes it a strong control variable.

30 S. Wurmet al.

7/21/2019 Wurm et al., 2010

8/19

Table2

.Correlationsamongtheindicatorsforthebaselinesample(N

4034)andlongitudinalsample(N

1286).

1

2

3

4

5

6

7

8

9

10

11

12

1

PV

A

0.16**

0.4

6**

0.0

5

0.0

7*

0.1

2**

0.1

5**

0.1

7**

0.0

9**

0.2

5**

0

.10**

0.0

3

2

Physicalhealth

0.2

5**

0.1

5**

0.0

0

0.0

2

0.0

7**

0.1

8**

0.1

1**

0.1

3**

0.3

8**

0

.10**

0.0

5

3

Ho

pe

0.5

3**

0.16**

0.0

6*

0.0

1

0.0

7**

0.0

1

0.1

0**

0.0

2

0.0

1

0

.00

0.0

3

4

Gender

0.0

2

0.00

0.0

7**

0.0

3

0.1

8**

0.0

3

0.0

5

0.0

0

0.0

5

0

.06*

0.0

8**

5

Pla

ceofresidence

0.0

6**

0.04**

0.0

4*

0.0

1

0.0

4

0.0

2

0.2

7**

0.0

4

0.0

6*

0

.22**

0.0

8**

6

Partner

0.1

7**

0.13**

0.1

2**

0.2

2**

0.0

4**

0.0

5

0.0

5

0.0

6*

0.2

0**

0

.05

0.0

8**

7

Education

0.1

9**

0.17**

0.0

7**

0.0

6**

0.0

1

0.0

7**

0.3

5**

0.5

1**

0.2

4**

0

.15**

0.0

8**

8

Inc

ome

0.1

8**

0.12**

0.1

6**

0.0

6**

0.2

1**

0.0

9**

0.3

4**

0.3

5**

0.1

0**

0

.17**

0.0

4

9

Pre

stige

0.1

8**

0.13**

0.1

1**

0.0

0

0.0

1

0.1

1**

0.5

1**

0.3

5**

0.0

9**

0

.17**

0.0

2

10

Age

0.3

7**

0.41**

0.0

8**

0.0

1

0.0

3

0.2

8**

0.2

5**

0.1

3**

0.1

3**

0

.15**

0.2

2**

11

Sports

0.2

0**

0.13**

0.1

0**

0.0

1

0.1

4**

0.1

1**

0.2

2**

0.2

0**

0.2

4**

0.2

2**

0.1

2**

12

Wa

lking

0.0

3

0.03*

0.0

7**

0.0

2

0.0

5**

0.0

4*

0.0

3*

0.0

1

0.0

2

0.1

6**

0

.10**

Notes:Valuesforthebaselinesamplea

rebelowthediagonal;valuesfo

rthelongitudinalsampleareabovethediagonal.

PVA

positiveviewonaging.

*p50.05

;**p50.0

1.


7/21/2019 Wurm et al., 2010

9/19

Socio-demographic characteristics (SDC)

Besides the Hope scale, socio-demographic indicators were also considered as control

variables to allow for the above mentioned impact of SDC on physical exercise. These are

variables on gender, living arrangement (with or without partner), place of residence

(Eastern or Western Germany), and level of education (1

low education, at most 9 yearsschool education, 2medium education, secondary school, 3high education, qualifying

for university admission). Additionally, we considered the equivalent household income

(a scale of the Organisation for Economic Co-operation and Development, OECD, on net

household income, weighted by the number of people sharing the household, cf. Piachaud,

1992) and a measure of occupational prestige (Treiman, 1977) that ranges from 18.1 (e.g.

sub workers) to 78.9 (e.g. physicians).

Age

Finally, we also included chronological age (in years) as control variable to consideradditionally the close relation between physical exercise and age.

Data analysis

Pearson product moment correlations were used to examine the interrelationship between

the study variables (Table 2). Descriptive data analysis and data screening revealed

significant skewness for physical activity of older adults; to exemplify, 63.2% of

participants aged 65 to 85 reported never doing sports while 39.3% of this age group

reported walking daily in the baseline sample. We, therefore, transformed both variables

for sports and walking logarithmically (loge transformation) which yielded a moresatisfactory distribution. Single missing values of the longitudinal as well as the baseline

sample were supplemented by data imputation with expectation maximization method,

which offers the advantage that there will be no systematic losses of participants who

missed single items (Dempster, Laird, & Rubin, 1977).

We analysed the data with LISREL 8.5 (Jo reskog & So rbom, 1996) as our computer

programme; maximum likelihood was used as estimation method. First, we computed latent

variable scores and scale reliabilities reported above with structural equation modelling

(SEM). This approach offers the possibility of accounting for measurement errors in the

manifest indicators (observed measures) and testing the assumed measurement model

empirically. Subsequently, we computed path models using the latent variable scores topredict physical exercise (i.e. walking or sports) both without and with adjustment for the

control variables health, hope, socio-demographic characteristics (gender, living arrange-

ment, place of residence, level of education, income, prestige) and, age. The longitudinal

analyses, with physical exercise at Time 2 as dependent variable, were additionally adjusted

for physical exercise at Time 1. We preferred path analyses using latent variable scores to

SEM because of the known theoretical and practical limitations of SEM with non-linear or

interaction effects (Bollen, 1989). In particular, significance tests and model fit statistics are

considered inappropriate for models involving interaction terms (Hu, Bentler, & Kano,

1992). Simulation studies show that this problem mainly occurs when the number of

manifest indicators is four or less (Jaccard & Wan, 1995), as was the case in the presentstudy. For the path models, the goodness of fit statistics are not described because the fit is

perfect.

32 S. Wurmet al.

7/21/2019 Wurm et al., 2010

10/19

Results

Cross-sectional analyses

The cross-sectional analyses investigated the question of whether a PVA is associated with

more regular physical exercise (Hypothesis 1). The results are summarised in Table 3. In

line with the hypotheses, the models on the sporting activity of middle-aged and olderadults showed that a PVA significantly predicted the frequency of doing sports both for

middle-aged (MA 0.14) and older adults (OA 0.20, ps50.001). These findings

remained significant after adjusting the control variables health, hope, six socio-

demographic variables and age (MA 0.08; OA 0.12; ps50.01). Hence, people with a

more PVA do sports more frequently than those with a less PVA. We additionally

computed a multi-group model to analyse whether PVA differs in its impact on

sporting activity between middle-aged and older adults; this turned out not to be the case

(2 (1) 0.40,p 0.54).

Next, we computed the same path model but predicted walking instead of sporting

activity. As expected, for middle-aged adults, PVA was only slightly associated with

more frequent walking (MA 0.04, p50.05; cf. Table 3), and became non-significant

after adjusting the analysis for all control variables (MA 0.03, p 0.17). By contrast,

PVA was associated with more frequent walking in older adults (OA 0.15, p50.001;

cf. Table 3), even after the adjustment of all control variables (OA 0.11, p50.01),

which was also in line with the hypothesis. Again, we additionally computed a multi-

group model to analyse whether both age groups differ significantly from each other.

In fact, PVA showed a significantly higher impact on walking for older adults than for

middle-aged adults (2 (1) 3.53, p50.05, one-tailed). Together, these results

corroborated our first hypothesis that PVA would be significantly related to sporting

activity among middle-aged adults as well as to doing sports and walking among older

adults.

Table 3. Prediction of sports and walking at time 1 by PVA in unadjusted models and covariate-adjusted models.a

Predictors at baseline

Sports Walking

Middle-agedadults

Olderadults

Middle-agedadults

Olderadults

R

2

R

2

R

2

R

2

Model 1: Unadjusted 0.02*** 0.04*** 0.00* 0.02***Positive view on ageing 0.14*** 0.20*** 0.04* 0.15***

Model 2: Health 0.02** 0.04 0.00 0.03*Positive view on ageing 0.13*** 0.20*** 0.04* 0.15***

Model 3: Hope 0.02 0.04 0.00 0.03Positive view on ageing 0.15*** 0.18*** 0.03 0.12***

Model 4: SES 0.11*** 0.10*** 0.01*** 0.03*Positive view on ageing 0.09*** 0.14*** 0.02 0.11***

Model 5: Age 0.12*** 0.11** 0.02*** 0.03Positive view on ageing 0.08** 0.12** 0.03 0.11**

Note: aBaseline sample, N 4034; *p50.05; **p50.01; ***p50.001.


7/21/2019 Wurm et al., 2010

11/19

Longitudinal analyses

By means of the longitudinal sample we subsequently examined whether PVA can predict

an increase in physical exercise over time (Hypothesis 2). For this, we performed the samepath models as before, except that we used physical exercise at T2 as dependent variable

while controlling for physical exercise at T1. The temporal stability for doing sports for

middle-aged adults and walking for older adults was of medium extent (rsports T1T2 0.44,

rwalking T1T2 0.34; ps50.001). Contrary to our hypothesis, PVA could not predict a

lower decrease in sporting activity either for middle-aged adults (MA 0.05,p 0.07) or

for older adults (OA 0.08, p 0.12; cf. Table 4); the additional multi-group model did

not show significant differences in this association between the age groups (2 (1) 0.07,

p 0.79).

As expected and in line with the findings for the cross-sectional model, PVA could

predict a lower decrease in walking for older adults (OA 0.11,p50.05; adjusted for allcontrol variables: OA 0.19, p50.01), but not for middle-aged adults (MA 0.00,

p 0.92). Here, the age groups differed significantly in the multi-group model

(2 (1) 6.85,p50.01).

Moderator analyses

Finally we explored whether health serves as a moderator in the relation between PVA and

physical activity, i.e. sporting activity in middle-aged adults as well as sporting activity and

walking in older adults (Hypothesis 3). For this, we computed the same path models as

before, but this time we added the PVAhealth interaction in each model.We first added this interaction term in the cross-sectional analyses. In contrast to

our expectations, the interaction term was not significant for doing sports, either for

Table 4. Prediction of sports and walking at time 2 by PVA in unadjusted models and covariate-adjusted models.a

Predictors at baseline

Sports Walking

Middle-agedadults

Olderadults

Middle-agedadults

Olderadults

R2

R2

R2

R2

Model 1: Adjusted for physical 0.20*** 0.19*** 0.16*** 0.11***Activity T1 (sports/walking)

Positive view on ageing0.05 0.08 0.00 0.11*

Model 2: Health 0.21** 0.19 0.16 0.15***Positive view on ageing 0.04 0.08 0.05 0.13*

Model 3: Hope 0.21 0.18 0.16 0.16**Positive view on ageing 0.05 0.08 0.01 0.20***

Model 4: SES 0.22** 0.21* 0.16 0.17Positive view on ageing 0.02 0.05 0.00 0.20**

Model 5: Age 0.22 0.26*** 0.17** 0.17Positive view on ageing 0.02 0.01 0.01 0.19**

Note: aLongitudinal sample, N 1286; *p50.05; **p50.01; ***p50.001.

34 S. Wurmet al.

7/21/2019 Wurm et al., 2010

12/19

middle-aged (MA0.10, p 0.33) or for older adults (OA 0.07, p 0.44). As

expected, the PVAhealth interaction turned out to be significant for the frequency of

walking for older adults (OA0.19, p50.05; adjusted for all control variables:

OA0.20,p50.05). The direction of this interaction effect was, however, unexpected.

Figure 1 reveals that older people with a more PVA are more likely to walk regularly when

they are in worse health. By contrast, people with a less PVA not only tend to be less active

in general, but also walk most rarely when they additionally have worse health.Second, we additionally tested the interaction term of PVA health in the

longitudinal model. Following our hypothesis, we again expected a significant

interaction for decreases in sporting activity for both middle-aged and older adults

and in walking for older adults. As expected, the interaction effect was significant for

decreases in sporting activity for middle-aged adults (MA 0.31, p50.05; adjusted for

all control variables: MA 0.31, p50.05); for older adults, the PVAhealth

interaction could not predict a lower decrease in sporting activities which is probably

due to the overall high sporting inactivity of older adults (OA 0.18, p 0.31). The

significant interaction for middle-aged adults is illustrated in Figure 2. The figure

reveals that those people who have good health and additionally high PVA do not onlyhave a lower decrease in sporting activity but even an increase over time. In contrast,

middle-aged adults with good health but a less positive view on ageing, maintain their

low level of physical exercise. Individuals with bad health reduce their physical activity,

regardless of their view on ageing.

Discussion

The present study provides evidence that a PVA may in fact contribute to a higher level of

physical exercise. This finding is in line with a previous study on general health behaviour

(Levy & Myers, 2004). To the best of our knowledge, this is the first study to examine theimportance of PVA for physical exercise. Moreover, the study considered not only older

adults but middle-aged adults as well. Thus we could analyse whether PVA is already

Low positiveView on aging

High positive1.2

1.3

1.4

1.5

1.6

Predictedvaluewa

lkingT1(log)

Bad health

Good health

Older adults (65 85 years)

Figure 1. Cross-sectional interaction effect of a PVAhealth on walking in older adults (database:baseline sample). Note: The figure depicts the values for the frequency of walking at T1 as predicted

by a PVA, health and the interaction between a PVA and health. Both a positive view on ageing (lowvs. high) and health (good vs. bad) were separated by median split for reasons of visual clarity.


7/21/2019 Wurm et al., 2010

13/19

important for physical exercise at the beginning of a time in which people become more

aware of their own ageing (Whitbourne, 2001), which was in fact the case.

The complementary analyses on doing sports and walking suggest that PVA may

counteract motivational barriers against physical exercise (Schutzer & Graves, 2004). PVA

was not related to walking in middle-aged adults. This was in line with the hypothesis that

the motivational barrier against walking would be rather low in middle adulthood because

functional disabilities which impede walking are not very common at this age. However,

middle-aged adults with high PVA not only did sports more frequently (cross-sectional

level), they even increased their sporting activity provided that they were healthy enough

to do so (longitudinal level). Thus, a PVA emerged as important for physical activities with

higher energy expenditure; these are highly recommended in midlife to promote weight

regulation and cardiovascular health. While middle-aged adults with high PVA and good

health increased their sporting activity over time, those with worse health reduced this

activity independent of their view on ageing (cf. Figure 2). This finding could reflect the

uncertainty of individuals with health problems about whether (and how much) physicalactivity is still beneficial in the light of their diseases.

Risk factors such as a sedentary lifestyle are often difficult to change and changes are

moderate even in patients who have enrolled in psychoeducational programmes

(e.g. Dusseldorp, van Elderen, Maes, Meilman, & Kraaij, 1999). In contrast to healthy

individuals who decide to change their behaviour, patients are told to change their

sedentary lifestyle but may not be convinced of the need (Johnston, 1999). The present

findings suggest that attitudes towards health behaviour change differ between individuals

with a more or less positive view on ageing. Individuals with a more PVA not only have

higher functional optimism (cf. Table 2), they additionally have further plans and goals for

the future. These might make it worth engaging in health behaviour because the pursuit ofgoals (e.g. travelling, hobbies, caring for grandchildren) requires sufficiently good health.

This is in line with studies on the importance of hoped-for selves on health behaviour

Time 1 Time 20.7

0.8

0.9

1.0

1.1

SportT1(log),predicted

valuesportT2(log)

Bad health, low PVA

Bad health, high PVA

Good health, lowPVA

Good health, highPVA

Middle-aged adults (40 64 years)

Figure 2. Longitudinal interaction effect of a PVAhealth on changes of sporting activity inmiddle-aged adults (database: longitudinal sample). Note: The figure depicts the values for thefrequency of doing sports at T2 as predicted by overall mean frequency of sporting activity at T1,a PVA, health and the interaction between a PVA and health. Both a PVA (low vs. high) and health(good vs. bad) were separated by median split for reasons of visual clarity.

36 S. Wurmet al.

7/21/2019 Wurm et al., 2010

14/19

(e.g. Hooker & Kaus, 1992; Oullette, Hessling, Gibbons, Reis-Bergan, & Gerrard, 2005).

In the light of their impact on motivation towards health behaviour change, conceptions

and misconceptions about ageing should be considered in the context of rehabilitation and

intervention programmes.

Also in line with our hypotheses was the finding that for older adults, PVA was

associated with higher physical activity, that is, doing sports and walking (cross-sectional

level). It was a remarkable result that even those older people with worse health walked

just as regularly as those with good health, provided that they had a PVA (cf. Figure 1).

This finding exceeded our expectations and emphasises the importance of a positive view

on ageing. Regular walking is often still recommended in spite of health problems,

ailments or frailty. This means, it is normally a more adaptive behaviour than a sedentary

lifestyle, even for ill or frail older people (Landi et al., 2004; WHO, 1997). Moreover, PVA

could predict an increase in the frequency of walking (longitudinal level). Hence, for older

adults, PVA was particularly associated with more regular walking. Moderate activities

such as walking are often considered to have top priority for older adults because they

promote functional ability and are even possible in cases of chronic disease and disabilities(DiPietro, 2001). Taken together, the findings for middle-aged and older adults in the

present study support the assumption that PVA contributes to physical exercise in later

adulthood.

The findings can be incorporated in the larger theoretical context of self-regulation

which places special emphasis on the importance of optimism and goal setting (e.g. De

Ridder & De Wit, 2006). Studies on optimism have repeatedly shown that people with a

more favourable expectation about the future have more beneficial health behaviour, and

are able to adapt better to negative conditions (e.g. Aspinwall, Richter, & Hoffman, 2001;

Taylor, Kemeny, Reed, Bower, & Gruenewald, 2000). However, favourable beliefs about

the future do not necessarily imply that people have gain-related goals. An optimistic viewof the future may also mean that a person is confident of maintaining his or her skills or

social relationships, or that a person is confident of successfully coping with losses.

Moreover, the present study did not focus on health goals but rather on the expectation

that ageing is accompanied by further development.

Thus, the finding is striking that such a PVA could predict physical exercise even if the

analyses were controlled for hope, that is, for functional optimism. This reveals that a

PVA cannot be equated with optimism and emphasises that gain-related goals continue to

be important up to old age. We have to keep in mind that the striving for personal

development mainly characterises the goal orientation of younger adults, while already

from middle adulthood there is a motivational shift toward conservation and loss-prevention (Heckhausen, 1997). Substantial reasons for this shift are the age-related

increase in physical and social losses and the shorter future time perspective (Carstensen,

Issacowitz, & Charles, 1999), but also the fact that older adults are more likely to have

already achieved their personal goals than younger adults. Hence the finding that a PVA

can motivate older people to physical exercise suggests that it remains important up to old

age to see the gains in life regardless of the age-related shift from striving for gains to

balancing losses.

LimitationsWe would like to point to some limitations concerning the generalisation of the present

study. First, all data used here are based on self-reports and thus might be biased. It would


7/21/2019 Wurm et al., 2010

15/19

be preferable to have additional data about physical exercise, although there is evidence

for the validity of self-reports on physical activity (Miller, Freedson, & Kline, 1994).

Second, sporting activity and walking were measured with single-item questions only.

Several studies point to a sufficient validity of single-item measures of physical activity

(e.g. Schechtman, Bazlai, Rost, & Fisher, 1991); however, the reliability of these measures

cannot be estimated and thus is questionable. Moreover, the present study used only ashort-term recall for the frequency of physical exercise. However, it has been shown that

the regularity of physical exercise is more important (Pate et al., 1995) and easier to

promote (Schwarzer, 2004) than the intensity. Finally, it would have been desirable to have

additional medical data; but self-reported health indicators turned out to conform to a

great extent with the health status evaluated by a physician (Bush, Miller, Golden & Hale,

1989; Kehoe, Wu, Leske, & Chylack, 1994).

A second limitation refers to the sample attrition of the longitudinal sample. Compared

to the original population-based survey, the longitudinal sample was selected in favour of

healthier and better-educated people who exercised more often (cf. Method section). Even

though we cannot rule out the possibility that the longitudinal findings are in part due tothe biased sample, two findings suggest that the findings can be generalised. First, the

present study has shown converging findings for the original survey sample and the

longitudinal sample which consistently point to the impact of a PVA on physical exercise

in later adulthood. Second, several ageing studies have examined the question of how

much the findings differ between a selected longitudinal sample and the corresponding

original baseline sample with estimated follow-up data for those people who dropped out

(Kempen & van Sonderen, 2002; Wurm, et al., 2007). These studies also report converging

findings between the different samples, and suggest that attrition not always seems a

serious problem when associations between variables (and not descriptive outcomes) are in

the focus.Finally, the variance explained in the regression models at baseline and follow-up was

relatively small. This could qualify the importance of a PVA for physical activity. First of

all, however, one should consider the 6-year period between baseline and follow-up. Any

changes in physical activity predicted by a PVA are, therefore, probably sustainable so

that cumulative benefits are very likely. Most importantly, we should bear in mind that the

small effects in physical activity as predicted by a PVA might be sufficient to cause a

substantial improvement in physical health. Numerous studies demonstrate the benefits of

even small increases in physical activity for health and longevity (Myers, et al., 2002; Pate

et al., 1995). Based on recent studies, Warburton, Nicol and Bredin (2006, p. 801) therefore

conclude that . . . an increase in energy expenditure from physical activity of 1000 kcal

(4200 kJ) or an increase in physical fitness of 1 MET (metabolic equivalent) per week was

associated with a mortality benefit of about 20%. The effect of physical activity is graded,

that is, even small improvements in physical activity are associated with a significant risk

reduction. For example, an intervention study for patients with diabetes showed that

patients who walked at least 2 h a week had a 39% lower mortality rate compared with

inactive individuals (Gregg, Gerzoff, Caspersen, Williamson, & Narayan, 2003). These

findings show that even small effects can result in important health benefits.

Conclusions and future directions

Besides these limitations, further aspects should be addressed in future studies.One issue concerns the number of and the time interval between follow-up surveys.

While intervention studies are often limited to a short follow-up period of less than half a

38 S. Wurmet al.

7/21/2019 Wurm et al., 2010

16/19

year, the present study referred to a time interval of 6 years. The fact that a PVA predicted

physical exercise over this long time interval is remarkable. But in future studies it would

be desirable to have more information about physical activity at more regular intervals.

This would also allow testing physical exercise as mediator between PVA and health.

Concerning the contribution of a PVA on health behaviour, future studies should also

extend their focus additionally to other health behaviour such as the use of preventive

medical checkups. The enhancement of health by physical exercise implies a value placed

on prospective gains, while illness-detection implies a value placed in avoiding losses

(Bailis, Fleming, & Segall, 2005). It has been shown that subjective risk factors cannot

predict physical exercise (Schwarzer, 2004). But for medical checkups and other health

behaviour aimed at averting losses, perceiving potential risks could be more beneficial than

having a positive view on ageing; an optimistically biased risk perception could prevent

this kind of health behaviour, which is also termed as defensive optimism (Schwarzer,

1994). The question of whether a PVA also promotes other aspects of a healthy lifestyle

should therefore be examined in future studies. But at least with regard to physical exercise

interventions and related public health programmes, it seems to be worthwhile to considera PVA as an additional motivator. In this context we have to keep in mind that such a

positive view cannot be taken for granted, not only because of the age-related losses but

also due to prevailing ageism and age stereotypes.

References

Aspinwall, L.G., Richter, L., & Hoffman, R.R.I. (2001). Understanding how optimism works: An

examination of optimists adaptive moderation of belief and behavior. In E. Chang (Ed.),

Optimism & pessimism: Implications for theory, research, and practice. Washington, DC:

American Psychological Association.

Bailis, D.S., Fleming, A.J., & Segall, A. (2005). Self-determination and functional persuasion to

encourage physical activity. Psychology and Health, 20, 691708.

Baltes, P.B., Lindenberger, U., & Staudinger, U.M. (1998). Life-span theory in developmental

psychology. In M.J. Lerner (Ed.), Handbook of child psychology. Vol I: Theoretical models of

human development (pp. 10291143). New York: Whiley.

Baltes, P.B., Schaie, K.W., & Nardi, A.H. (1971). Age and experimental mortality in a seven-year

longitudinal study of cognitive behavior. Developmental Psychology, 5, 1826.

Blair, S.N., Kohl, H.W., Gordon, N.F., & Paffenbarger, R.J. (1992). How much physical activity is

good for health? Annual Review of Public Health, 13, 99126.

Blumenthal, J.A., & Gullette, E.C.D. (2002). Exercise interventions and aging: Psychological

and physical health benefits in older adults. In K.W. Schaie, H. Leventhal, &

S.L. Willis (Eds.), Effective health behavior in older adults (pp. 157178). New York:

Springer.

Bollen, K.A. (1989). Structural equations with latent variables. New York: John Wiley.

Burton, L.C., Shapiro, S., & German, P.S. (1999). Determinants of physical activity

initiation and maintenance among community-dwelling older persons. Preventive Medicine,

29, 422430.

Bush, T.L., Miller, S.R., Golden, A.L., & Hale, W.E. (1989). Self-report and medical record report

agreement of selected medical conditions in the elderly. American Journal of Public Health, 79,

15541556.

Carstensen, L.L., Issacowitz, D.M., & Charles, S.T. (1999). Taking time seriously. A theory of

socioemotional selectivity. American Psychologist, 54, 165181.Dempster, A.P., Laird, N.M., & Rubin, D.B. (1977). Maximum likelihood from incomplete data via

the EM algorithm. Journal of the Royal Statistical Society, Series B, 122.


7/21/2019 Wurm et al., 2010

17/19

7/21/2019 Wurm et al., 2010

18/19

Landi, F., Cesari, M., Onder, G., Lattanzio, F., Gravina, E.M., & Bernabei, R. (2004). Physical

activity and mortality in frail community-living patients. Journals of Gerontology: Medical

Sciences, 59A, M833M837.

Levy, B.R., & Myers, L.M. (2004). Preventive health behavior influenced by self-perceptions of

aging. Preventive Medicine, 39, 625629.

Levy, B.R., & Myers, L.M. (2005). Relationship between respiratory mortality and self-perceptionsof aging. Psychology and Health, 20, 553564.

Levy, B.R., Slade, M.D., & Kasl, S.V. (2002). Longitudinal benefit of positive self-perceptions of

aging on functional health. Journals of Gerontology: Psychological Sciences, 57B, P409P417.

McAuley, E., Jerome, G.J., Elavsky, S., Marquez, D.X., & Ramsey, S.N. (2003). Predicting long-

term maintenance of physical activity in older adults. Preventive Medicine, 37, 110118.

Miller, D.J., Freedson, P.S., & Kline, G.M. (1994). Comparison of activity levels using the Caltrac

accelerometer and five questionnaires.Medicine and Science in Sports and Exercise, 26, 376382.

Morley, J.E., & Flaherty, J.H. (2002). Its never too late: Health promotions and illness prevention in

older persons. Journals of Gerontology: Medical Sciences, 57A, M338M342.

Myers, J., Prakash, M., Froelicher, V., Do, D., Partington, S., & Atwood, E. (2002). Exercise

capacity and mortality among men referred for exercise testing. The New England Journal ofMedicine, 346, 793801.

Neller, K. (2005). Kooperation und Verweigerung: Eine Non-Response-Studie [Co-operation and

refusal: A non-response study]. ZUMA-Nachrichten, 57, 936.

Neugarten, B.L. (1996). The Meaning of Age. Chicago: The University of Chicago Press.

Newsom, J.T., Kaplan, M.S., Huguet, N., & McFarland, B.H. (2004). Health behaviors in a

representative sample of older Canadians: Prevalences, reported change, motivation to change,

and perceived barriers. The Gerontologist, 44, 193205.

Norris, F.H. (1985). Characteristics of older non-respondents over five years of a panel study.

Journal of Gerontology, 40, 627636.

Oullette, J.A., Hessling, R., Gibbons, F.X., Reis-Bergan, M., & Gerrard, M. (2005). Using images to

increase exercise behavior: Prototypes versus possible selves. Personality and Social PsychologyBulletin, 31, 610620.

Paffenbarger Jr, R.S., Kampert, J.B., Lee, I.-M., Hyde, R.T., Leung, R.W., & Wing, A.L. (1994).

Changes in physical activity and other lifeway patterns influencing longevity. Medicine and

Science in Sports and Exercise, 26, 857865.

Pate, R.R., Pratt, M., Blair, S.N., Haskell, W.L., Macera, C.A., Bouchard, C., et al. (1995). Physical

activity and public health: A recommendation from the Centers for Disease Control and

Prevention and the American College of Sports Medicine. The Journal of the American Medical

Association, 273, 402407.

Paterson, D.H., Govindasamy, D., Vidmar, M., Cunningham, D.A., & Koval, J.J. (2004).

Longitudinal study of determinants of dependence in an eldery population. Journal of the

American Geriatrics Society, 52, 16321638.Piachaud, D. (1992). Wie mit man Armut? [How to measure poverty?]. In S. Leibfried, &

W. Voges (Eds.), Armut im modernen Wohlfahrtsstaat. Kolner Zeitschrift fur Soziologie und

Sozialpsychologie, Sonderheft 32 (pp. 6387). Opladen: Westdeutscher Verlag.

Prochaska, J.O., & Velicer, W.F. (1997). The transtheoretical model of health behavior change.

American Journal of Health Promotion, 12, 3848.

Rakowski, W. (1986). Future time perspective. Applications to the health context of later adulthood.

American Behavioral Scientist, 29, 730745.

Raykov, T. (2004). Estimation of maximal reliability: A note on a covariance structure modelling

approach. British Journal of Mathematical and Statistical Psychology, 57, 2127.

Schaie, K.W., & Willis, S.L. (2002). Adult development and aging. Upper Saddle River, NJ: Prentice

Hall.

Schechtman, K.B., Bazlai, B., Rost, K., & Fisher Jr, E.B. (1991). Measuring physical activity with a

single question. American Journal of Public Health, 81, 771773.


7/21/2019 Wurm et al., 2010

19/19

Documents

Wurm et al., 2010