Journal of Physical Activity and Health, 2014, 11, 1482  -1491 http://dx.doi.org/10.1123/jpah.2012-0504 © 2014 Human Kinetics, Inc.

Official Journal of ISPAH www.JPAH-Journal.com ORIGINAL RESEARCH

Associations of Leisure Time, Commuting, and Occupational Physical Activity With Physical Fitness and Cardiovascular Risk Factors in Young Men Jani P. Vaara, Heikki Kyröläinen, Mikael Fogelholm, Matti Santtila, Arja Häkkinen, Keijo Häkkinen, and Tommi Vasankari Background: The aim was to study the relationships between different domains of physical activity and cardiovascular risk factors and physical fitness. Methods: 781 young men participated. Self-reported leisure-time (LTPA), commuting (CPA) and occupational (OPA) activity were determined. Blood pressure, s-HDL-cholesterol, s-triglycerides and s-LDL-cholesterol, and glucose were measured. The continuous cardiovascular disease (CVD) risk factor score was calculated from the z-score mean of each cardiovascular risk factor. The cutpoint was defined as 1 standard deviation above the mean. Cardiorespiratory and muscular fitness were measured. Results: The likelihood of CVD risk factor score was higher in moderate [OR 1.99 (95% CI 1.21–3.28)] and low [1.87 (1.16–3.02)] CPA groups compared with the high group, whereas neither low nor moderate LTPA or OPA groups showed similar associations after adjustments. Low OPA combined either with low LTPA [2.01 (1.08–3.74)] or low CPA [1.90 (1.05–3.44)] had a higher likelihood for CVD risk factor compared with combined moderate-high categories after adjustments. LTPA was positively associated with all physical fitness parameters, CPA with cardiorespiratory fitness and muscular endurance, and OPA with grip strength. Conclusion: The results emphasize the beneficial role of CPA regarding CVD risk factor score and stress the avoidance of low physical activity in its different domains. Keywords: cardiometabolic risk factors, exercise, cross-sectional Regular physical activity is beneficial for preventing chronic cardiovascular diseases (CVD). It has been shown that a high level of physical activity (PA) reduces the risk for all-cause and cardiovascular mortality,1 as well as for CVD.2 In addition, a high level of physical activity is associated with lower levels of cardiovascular risk factors (eg, blood lipids and blood pressure).3 The current physical activity recommendations are not specific to any physical activity domain, but simply emphasize any physical activity. Nonetheless, total physical activity has been categorized in previous studies to leisure-time physical activity (LTPA), commuting (CPA), and occupational (OPA) physical activities. Recent epidemiological studies have observed decreasing trends for occupational and commuting physical activities in recent decades4,5 whereas LTPA has shown an increasing trend.5 Therefore, it is of interest to study the independent associations of each physical activity domain, as well as their joint associations with cardiovascular risk factors. The majority of previous studies concerning CVD and its risk factors have concentrated on LTPA. Commuting and occupational physical activities are less studied, although an increasing attention has been focused on them during Vaara ([email protected]) is with the Dept of Leadership and Military Pedagogy, National Defence University, Helsinki, Finland. Kyröläinen and K Häkkinen are with the Dept of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland. Fogelholm is with the Dept of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland. Santtila is with the Personnel Division of Defence Command, Finnish Defence Forces, Helsinki, Finland. A Häkkinen is with the Dept of Health Sciences, University of Jyväskylä, Jyväskylä, Finland. Vasankari is with The UKK Institute for Health Promotion Research, Tampere, Finland. 1482

the recent decades.6,7 Nonetheless, there are only a few studies available that have simultaneously assessed leisure time, commuting, and occupational physical activity and cardiovascular risk factors.8,9 A recent review of prospective studies concluded that LTPA is inversely associated with CVD.10 Similarly, Hamer and Chida6 showed a beneficial association between CPA and CVD risk in their meta-analyses of prospective studies. However, the association between OPA and CVD seems to be more controversial showing that either moderate10,11 or high12 OPA have the strongest inverse relationship with CVD, whereas a positive relationship has also been observed between high OPA and CVD risk outcomes.7,13 Furthermore, previous studies have observed mixed results concerning the association between CVD risk factors and PA domains.14–23 Most of these studies have assessed associations between physical activity and individual CVD risk factors. Therefore, the clustered cardiovascular risk factor was also used in the current study3 because the risk factors tend to occur simultaneously rather than individually.24 There is strong evidence to show that regular physical activity, especially leisure-time physical activity, has a positive influence on physical fitness.25 Active commuting is also positively associated with aerobic fitness, however this has been reported by a surprisingly few studies.26–28 Information about the association between CPA and muscular fitness is especially limited. Andersen et al27 found in children that muscular endurance was better in children who cycle to school compared with those walking or traveling passively, whereas there is no data available in adults. Furthermore, mixed results have been reported between OPA groups in terms of aerobic29–31 and in muscular fitness.31–34 The aim of the current study was to assess relationships between different domains of physical activity and single and clustered cardiovascular risk factor. In addition, physical fitness characteristics

Physical Activity and Cardiovascular Risk Factors in Young Men   1483

including both cardiorespiratory and muscular fitness were compared between the activity groups in each of the physical activity domain. Our hypothesis was that LTPA and CPA are related to the continuous CVD risk factor score and physical fitness, whereas OPA is not.

Methods

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Study Procedures and Participants Participants were 846 young (25.5 ± 5.0 yrs.) adult Finnish men, who were called up to military refresher training. Participants who reported using medication for diabetes, high cholesterol or hypertension (n = 8) were excluded. Only those participants who completed all of the blood samplings, blood pressure and waist circumference measurements were selected for further analysis concerning CVD risk factors (n = 686) and similarly only those who completed all of the physical fitness tests were selected for analysis concerning physical fitness (n = 781). The study sample was compared with corresponding cohorts of 20 to 30 years old Finnish men in the national register data (Statistics Finland) from the years 2007–2008 for age, education and place of residence. The current study sample is not fully nationally representative, since Northern Finland was under-represented in this study sample and those with 13 to 15 years of education were slightly overrepresented. The call up to military refresher training and information about the study plan for participants were sent to participants 5 months before the measurements, which were carried out in 8 different sessions during 2008. The study protocol was explained in detail to the participants before they gave written consent. The study was approved by the ethical committees of the University of Jyväskylä and the Central Finland Health Care District, as well as the Headquarters of the Finnish Defense Forces. The measurements started in the morning after a night of sleep with an overnight fast.

Assessment of Physical Activity Self-Reported LTPA.  The frequency and intensity of weekly

LTPA was determined with the following question: “Which of the following definitions best describe your leisure time physical activity habits? - (“Think of the last 3 months and consider all leisure-time physical activity that lasted at least 20 minutes per session”). Response categories were (1) less than once a week; (2) no vigorous activities, but light or moderate physical activity at least once a week (if more often than once please define the numbers per week in an open space); (3), vigorous activity once a week; (4) vigorous activity twice a week; (5) vigorous activity 3 times a week; (6) vigorous activity at least 4 times a week. LTPA was classified as low (responses 1 or 2), moderate (responses 3 or 4), and high (responses 5 or 6) activity.35 The LTPA question used in the current study has been validated against fitness, observing that vigorous physical activity showed a consistent dose-response relationship with cardiorespiratory and muscular fitness. 35 There is no specific study available concerning validation against objective physical activity measurement and the LTPA question used herein. In general, acceptable to good reliability but poor to moderate validity have been reported for physical activity questionnaires.36 Self-Reported CPA.  The engagement and duration of CPA was

determined with the following question: “How many minutes do you walk or cycle during on your way to and from work, and when running errands per day? Response categories were (1) no walking or cycling to work, (2) less than 15 minutes a day, (3) 15–29 minutes

a day, (4) 30–59 minutes a day, and (5) 60 minutes or more a day. CPA was classified as low (responses 1 or 2), moderate (response 3) and high (responses 4 or 5) activity.8 Moderate test-retest reliability has been shown in a previous study using similar questions (min/ week) about commuting physical activity (ICC = 0.53, 95% CI: 0.37–0.65).37 To the best of our knowledge, the present questionnaire has not been validated previously, although it has been widely used in earlier population-based studies.8,9 Self-Reported OPA.  OPA was assessed with the following question: “How physically demanding is your work? (if you are not working at present, please answer concerning your previous work).” Response categories were (1) mostly sedentary work without much walking, (2) walking quite a lot at work without lifting or carrying heavy objects, (3) lots of walking and lifting at work or taking the stairs or walking uphill, and (4) physically very demanding work including lots of lifting or bearing heavy objects, digging, or shoveling at work. OPA was further classified as low (response 1), moderate (responses 2 or 3) and high (response 4) activity.9 Good repeatability of single-item OPA questions similar to the one used in the current study has been shown in previous studies (Kw = 0.80),38 (ICC = 0.82).37 In addition, moderate subjective criterion validity against physical activity records (ICC = 0.57–0.82) have been reported for the individual answer options (hours per week).39 Moreover, moderate construct validity has been reported between single-item OPA questions against several accelerometers (r = –0.45 to 0.48).38 Selected Cardiovascular Risk Factors.  Selected cardiovascular

risk factors consisted of blood pressure, serum lipids and plasma glucose. Blood pressure was recorded twice at 1- to 2-min intervals in a seated position using an automatic blood pressure device (Omron M6 Comfort, Netherlands). In the analysis, a mean of the 2 values was used. Blood samples were drawn from the ulnar vein using Terumon Venosafe (Terumo Europe, Leuven, Belgium) and were centrifuged at speed of 3500 rpm. Glucose, serum high density lipoprotein cholesterol (HDL) and triglycerides (TG) were analyzed by the Konelab 20 XTi -device (Thermo Electron Co, Vantaa, Finland) and the isolated low density lipoprotein cholesterol (LDL) fraction was used for direct measurement of LDLcholesterol (CHOD-PAP method). The ranges for triglycerides, HDL cholesterol, and LDL cholesterol assays were 0.1–15, 0.09–11, 0.04–2.84, and 0.3–8.9 mmol·l-1, respectively. Intra- and interassay coefficients of variance were 1.0% and 3.8% for TG, 3.4 and 3.9 for s-LDL, and 0.5% and 7.6% for s-HDL, respectively. Sensitivity for glucose was 0.1 mmol/l, and intra- and interassay coefficients of variance, 1.0 and 2.0%, respectively. A continuous clustered cardiovascular risk factor score was used in the current study similar to earlier studies,40,41 consisting of glucose, serum triglycerides, serum high-density lipoprotein cholesterol, serum low-density lipoprotein cholesterol, and systolic and diastolic blood pressure. First, the values of each cardiovascular risk factor were transformed to z-scores. HDL cholesterol was inverted before being included in the risk score. The continuous clustered risk factor score was calculated from the mean of z-score values of all cardiovascular risk factors. The cutpoint for cardiovascular risk was defined as 1 SD above the mean.40,42 Cardiorespiratory Fitness.  Cardiorespiratory fitness (VO2max)

was estimated using an indirect graded cycle ergometer test (Ergoline 800S, Ergoselect 100K, Ergoselect 200K, Bitz, Germany). A progressive protocol started at a power output of 50 W and was increased 25 W every 2 minutes until exhaustion. Heart rate (HR) was continuously recorded during the test (Polar Vantage NV or

1484  Vaara et al

S610, S710, or S810, Kempele, Finland). Predicted VO2max was estimated from HR and maximal power (W) (Fitware, Mikkeli, Finland) with the following equation: VO2max (ml·kg–1·min–1) = 12.35 × Pmax/kg + 3.5, where Pmax is maximal power and kg is body mass in kg. The intra class correlation has been reported to be high with this method (ICC r = .82–.94) for men.43

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Muscular Fitness.  Muscular endurance tests consisted of push-

ups, sit-ups, and repeated squats (repetitions/minute). There was a recovery period of 5 min between the tests. Correct technique was demonstrated to participants before each test and only the trials with adequate technique were accepted. Maximal isometric leg and bench press strength were measured using dynamometers. Knee angle was set to 107° with a goniometer, and the hands were placed on the handle grip in the leg press test. During the maximal bench press test, the participants were in a supine position with back flat on a bench and feet flat on the floor with elbow and shoulder joints positioned at 90°. A warm-up series of at least 2 submaximal sets were done before maximal sets. Three trials were performed using 30 s recovery periods. The best performance was included in the analysis. Maximal force was recorded with an AD-converter (CED power 1401, Cambridge Electronic Design, ltd, England) at a frequency of 1-kHz on a computer. The information about validity and repeatability of the fitness tests in the current study has been reported elsewhere.44

Body Composition.  Waist circumference was measured by a tape measure at the level of iliac crest after exhaling and body fat

percentage was determined by the bioelectrical impedance (BIA) method (Inbody 720, Biospace Company, Seoul, Korea). Statistics.  Data were analyzed with R program for statistical

computing and PASW-software (PASW for Windows 18.0.1). Means and standard deviations (SD) were calculated in the categories for low, moderate and high leisure time, commuting and occupational physical activity. Analysis of covariance with Bonferroni post hoc was used to compare physical fitness, body composition and CVD risk factors between the low, moderate and high categories in each physical activity domain. Covariates included age, smoking, the other 2 physical activity domains and waist circumference. Multinomial logistic regression was used to estimate the odd ratios and the 95% CI for the continuous CVD risk factor score using the highest category as the reference group in each of the physical activity domain. To calculate the odds ratio, cardiovascular risk was dichotomized at the cutpoint value of above 1 SD, similar to the earlier studies.40,42 In addition, the likelihood for the higher continuous CVD risk factor score was estimated using combinations of moderate-high physical activity categories and the low activity groups (see Table 5). The moderate-high groups served as a reference group.

Results Characteristics of background information for physical fitness, body composition and selected cardiovascular risk factors are presented in Table 1.

Table 1  Characteristics of the Study Population Mean

SD 5.0

Background

Age (year) Current smokers (%)

25.0 38.3

Leisure-time physical activity

Low (%) Moderate (%) High (%)

29.7 39.8 30.4

Commuting physical activity

Low (%) Moderate (%) High (%)

27.6 37.7 34.6

Occupational physical activity

Low (%) Moderate (%) High (%)

26.5 19.4 54.1

Body composition

Waist circumference (cm) % body fat

86.3 17.9

10.4 7.2

Fitness

VO2max (mL·min–1·kg–1) Push-ups (reps/min) Repeated squats (reps/min) Sit-ups (reps/min) Grip strength (kg) Bench press (N) Leg extension (N)

41.6 28.8 43.7 38.0 53.2 890 2943

8.1 12.8 8.5 10.2 8.9 199 873

Cardiovascular disease risk factors

Systolic pressure (mm/Hg) Diastolic Pressure (mm/Hg) HDL (mmol/L) LDL (mmol/L) Glucose (mmol/L) Triglycerides (mmol/L)

123.0 76.8 1.49 2.43 5.40 1.03

11.8 8.4 0.36 0.63 0.41 0.53

Physical Activity and Cardiovascular Risk Factors in Young Men   1485

Physical Activity, Physical Fitness, and Body Composition After adjustment for age, smoking, and the other 2 types of physical activity, a positive trend for all fitness parameters and waist circumference were found across the LTPA groups, whereas a positive trend was found for cardiorespiratory fitness, sit-ups, repeated squats, and waist circumference across the CPA groups. Furthermore, the high OPA group had higher values for grip strength compared with the low activity group (Table 2).

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Physical Activity and Selected Cardiovascular Risk Factors The high LTPA group had a lower concentration of glucose and higher systolic blood pressure compared with the moderate group, as well as higher HDL -cholesterol compared with the low group after adjustment for age, smoking and the other 2 types of physical activity (Table 3). The high CPA group had significantly lower systolic and diastolic blood pressure compared with the low CPA group (Table 3). After further adjustment for waist circumference, statistically significant differences between the activity groups remained for systolic blood pressure across the LTPA groups only and for plasma glucose between OPA groups (Table 3). In the multinomial regression analyses, the likelihood for having the continuous CVD risk factor score was significantly higher in the moderate and low CPA groups compared with the high CPA group after adjustment for age smoking and the other 2 types of physical activity. Additional adjustment for waist circumference attenuated the likelihood. However, the moderate CPA group had a higher likelihood compared with the high CPA group. Moreover, the likelihood was not significantly higher in the low or moderate LTPA or OPA groups when compared with their high physical activity reference groups (Table 4). Combinations of low LTPA and low CPA, as well as low LTPA and low OPA, had a higher likelihood for having continuous CVD risk factor score when compared with their moderate-high groups. Nonetheless, further adjustment for waist circumference revealed no statistically significant differences (Table 5).

Discussion The main findings of the current study were that moderate and high CPA was associated with reduced likelihood for the continuous CVD risk factor score compared with low CPA, whereas a similar association was not evident in LTPA or OPA. In addition, low LTPA combined with either low OPA or low CPA was related to increased likelihood for the continuous CVD risk factor score compared with their combined moderate-high physical activity category. In line with a previous study,45 an increased likelihood for the continuous CVD risk factor score was found in the low and moderate CPA groups compared with the high CPA group. These associations attenuated after adjustment for waist circumference leaving a statistical significance only between moderate and high groups. Similar to an earlier finding,9 no consistent pattern for differences in single CVD risk factors between CPA groups was observed. In the current study the high CPA group had lower systolic and diastolic blood pressure compared with the low group. Previous studies have shown an inverse relationship between CPA and triglycerides18,28 and blood pressure,18,28 whereas no association has been observed with LDL-cholesterol,18,28 glucose,28 and blood pressure.8,9,18,28 In addition, a positive relationship has been observed between HDL-

cholesterol and CPA in some9,18 but not all studies.28 It is noteworthy that in some of these studies8,9 body mass index was adjusted in the analysis whereas in others it was not.18,28 This may partly explain the controversial findings observed. No significant association was observed between LTPA and clustered CVD risk in the current study. In contrast, most of the earlier findings from cross sectional studies have shown that high LTPA is associated with reduced likelihood for the clustered CVD risk factors,3,46–48 whereas a lack of association has also been observed.49 A significant association was observed between continuous CVD risk factor score and CPA but not with the LTPA in the current study. With the use of the present CPA question it was not possible to detect the intensity of the activity. Therefore, it is not possible to discuss whether the significant association is related to intensity in addition to volume or their combination. The LTPA question included light to moderate and vigorous type of activity and thus detailed analyses were executed (data not shown). These results indicated that physical activity volume had no effect, whereas intensity had a statistically significant effect. Light or moderate exercise more than 3 times per week was not associated with CVD risk factor, whereas vigorous activity more than 3 times per week was associated (P < .009). Previously it has been shown that the volume of physical activity may be more closely related to cardiovascular risk factors than the intensity,50 whereas studies also show the benefits of high intensity physical activity on CVD risk factors. Nonetheless, it has also been concluded that high intensity physical activity may not induce superior improvements compared with lower intensity physical activity.51 Moreover, it should be noted that LTPA has been repeatedly shown to be negatively associated with clustered CVD risk factors in previous studies, which may suggest that measurement error, confounding factors or over-reporting of LTPA may have existed in the current study.35 Furthermore, the participants of the current study were young and healthy adults, and therefore the association may not be as strong as compared studies with older participants. The high LTPA group had a lower concentration of plasma glucose and a higher concentration of HDL-cholesterol compared with the low activity group. However, these differences were small indicating little clinical significance. After further adjustment for waist circumference these associations became nonsignificant, which suggests that the effect of LTPA on CVD risk factors may in part be mediated through waist circumference. Previous cross sectional studies have reported that LTPA is inversely associated with LDL-cholesterol,14–16 triglycerides,14,15,18 and blood pressure,9,14 whereas a lack of association has also been observed with LDL-cholesterol,17,18,52 triglycerides,16,17,47,52 glucose,40 and blood pressure.15,16,18,47 The most consistent positive association in cross sectional studies has been reported between HDL-cholesterol and LTPA,9,14,15,17,18,52 although in 1 study no association was reported.47 The mechanisms explaining the beneficial effects of physical activity may include, for example, increased skeletal muscle lipoprotein lipase activity,53 decreased hepatic triglyceride lipase activity,54 and increased muscle GLUT4 content.55 Surprisingly, the high LTPA group had higher systolic pressure compared with the low activity group in the current study. The reasons for these positive associations observed here and in some earlier cross-sectional studies8,9 remain unknown. However, some potential confounders, which were not detected in the current study, such as nutritional factors (salt intake) or stress may play a role as mediators. In addition, the difference between high and low LTPA levels were about the same range that can be detected (1–3 mm/ Hg). The mean values of the systolic blood pressure were clearly in

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41.6 ± 7.3

45.7 ± 8.1

 Moderate

 High

41.6 ± 8.1

43.4 ± 8.1

 Moderate

 High

42.4 ± 8.3

41.8 ± 7.9

 Moderate

 High

A, b

a

A, B

A

29.8 ± 12.5

27.4 ± 12.6

27.9 ± 13.1

30.6 ± 13.2

28.3 ± 12.7

27.1 ± 12.3

37.0 ± 12.7

26.6 ± 11.2

23.5 ± 10.9

Push-ups (reps/min)

A, B

a

43.6 ± 8.7

44.3 ± 7.7

43.6 ± 8.7

45.3 ± 8.8

43.9 ± 7.4

41.6 ± 9.2

47.5 ± 7.4

43.9 ± 7.9

39.9 ± 8.7

Repeated squats (reps/min)

A

A, B

A

37.7 ± 9.7

38.6 ± 10.6

38.5 ± 10.8

39.1 ± 9.9

38.5 ± 10.2

36.0 ± 10.3

43.6 ± 10.0

37.6 ± 8.9

33.1 ± 9.1

Sit-ups (reps/min)

a

A, B

A

53.9 ±8.7

52.6 ± 8.6

52.3 ± 9.7

52.7 ± 8.4

53.2 ± 9.2

53.6 ± 9.2

54.3 ± 9.4

52.6 ± 8.5

52.7 ± 8.9

Grip strength (kg)

a

b

909 ± 191

884 ±186

899 ± 222

903 ± 199

906 ± 201

888 ± 196

1009 ± 227

872 ± 162

829 ± 167

Bench press (N)

A, B

a

2955 ± 879

2920 ± 885

2960 ± 864

3032 ± 943

2894 ± 796

2894 ± 873

3162 ± 924

2939 ± 830

2739 ± 826

Leg extesion (N)

A, b

85.8 ± 10.5

86.2 ± 9.1

86.9 ± 10.8

84.8 ± 8.3

86.5 ± 10.6

87.5 ± 11.7

84.8 ± 8.3

86.5 ± 10.6

87.5 ± 11.7

Waist circumference (cm)

Abbreviations: LTPA, leisure-time physical activity; CPA, commuting physical activity; OPA, occupational physical activity. Note. a = different from low activity group (P < .05); A = different from low activity group (P < .001); b = different from moderate activity group (P < .05); B = different from moderate activity group (P < .001).

40.9 ± 8.0

 Low

OPA

39.4 ± 7.6

 Low

CPA

37.6 ± 6.9

 Low

LTPA

VO2max (mL·min-1·kg-1)

Table 2  Group Comparisons for Physical Fitness and Waist Circumference (Mean + SD) Between the Activity Groups in LTPA, CPA, and OPA Adjusted for Age, Smoking, and the Other 2 Types of Physical Activity

1486 a

a

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121.4 ± 11.4

124.8 ± 12.3

 Moderate

 High

123.1 ± 11.6

121.7 ± 11.7

 Moderate

 High

122.8 ± 11.3

122.9 ± 11.8

 Moderate

 High

a

b

M1

a

M2

76.5 ± 8.6

76.3 ± 7.7

77.4 ± 8.2

75.7 ± 8.0

76.8 ± 8.7

78.0 ± 8.1

76.9 ± 8.4

75.8 ± 8.0

77.8 ± 8.6

Diastolic blood pressure (mm/Hg)

a

a

M1

a

M2

1.50 ± 0.36

1.48 ± 0.36

1.47 ± 0.37

1.51 ± 0.35

1.49 ± 0.36

1.47 ± 0.37

1.55 ± 0.35

1.49 ± 0.38

1.44 ± 0.34

Serum HDLcholesterol (mmol/L)

a

M1

M2

2.40 ± 0.63

2.45 ± 0.60

2.45 ± 0.65

2.41 ± 0.55

2.40 ± 0.62

2.48 ± 0.71

2.35 ± 0.58

2.45 ± 0.64

2.47 ± 0.65

Serum LDLcholesterol (mmol/L) M1

M2

5.42 ± 0.41

5.38 ± 0.43

5.35 ± 0.39

5.43 ± 0.41

5.36 ± 0.41

5.38 ± 0.41

5.36 ± 0.41

5.43 ± 0.39

5.39 ± 0.44

Plasma glucose (mmol/L)

b

M1

a

M2

1.01 ± 0.48

1.02 ± 0.55

1.05 ± 0.58

0.96 ± 0.39

1.05 ± 0.58

1.07 ± 0.59

0.96 ± 0.49

1.01 ± 0.48

1.11 ± 0.60

Serum triglycerides (mmol/L)

M1

M2

Abbreviations: LTPA, leisure-time physical activity; CPA, commuting physical activity; OPA, occupational physical activity. Note. a = different from low activity group (P < .05); b = different from moderate activity group (P < .05). Model 1 (M1) adjusted for age, smoking and the other 2 types of physical activity. Model 2 (M2) adjusted for age, smoking, the other 2 types of physical activity and waist circumference.

123.2 ± 12.3

 Low

OPA

124.5 ± 12.2

 Low

CPA

123.2 ± 11.7

 Low

LTPA

Systolic blood pressure (mm/Hg)

Table 3  Group Comparisons for Selected Cardiovascular Risk Factors (Mean + SD) Between the Activity Groups in LTPA, CPA, and OPA

1487

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Table 4  Odds Ratios for Having the Continuous Cardiovascular Disease Risk Factor Score in the LTPA, CPA, and OPA Groups Model 1

Model 2

 Low

1.39 (0.82–2.35)

0.96 (0.54–1.69)

 Moderate

0.98 (0.59–1.63)

0.70 (0.41–1.21)

1

1

 Low

1.87 (1.16–3.02)

1.54 (0.91–2.59)

 Moderate

1.99 (1.21–3.28)

2.00 (1.17–3.41)

1

1

 Low

1.04 (0.65–1.64)

0.96 (0.58–1.58)

 Moderate

0.72 (0.41–1.26)

0.75 (0.42–1.37)

1

1

LTPA

 High CPA

 High

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OPA

 High

Abbreviations: LTPA, leisure-time physical activity; CPA, commuting physical activity; OPA, occupational physical activity. Note. Model 1 adjusted for age, smoking, and the other 2 types of physical activity. Model 2 adjusted for age, smoking, the other 2 types of physical activity, and waist circumference

Table 5  Joint Associations of Low and Moderate-to-High LTPA, CPA, and OPA Physical Activity With the Continuous CVD Risk Factor Score Model 1

Model 2

Low LTPA/Low CPA

1.90 (1.05–3.44)

1.53 (0.80–2.91)

Mod-high LTPA/Low CPA

1.40 (0.81–2.42)

1.10 (0.61–1.98)

Low CPA/Mod-high CPA

1.45 (0.85–2.47)

1.21 (0.68–2.16)

1

1

Low LTPA/Low OPA

2.01 (1.08–3.74)

1.64 (0.83–3.23)

Mod-high LTPA/Low OPA

0.94 (0.53–1.66)

0.88 (0.48–1.61)

Low LTPA/Mod-high OPA

1.17 (0.70–1.97)

1.08 (0.62–1.88)

Mod-high LTPA/Mod high CPA

Mod-high LTPA/Mod high OPA

1

1

Low CPA/Low OPA

1.69 (0.86–3.33)

1.29 (0.61–2.71)

Mod-high CPA/Low OPA

1.14 (0.67–1.96)

1.07 (0.60–1.90)

Low CPA/Mod-high OPA

1.32 (0.79–2.20)

1.13 (0.65–2.00)

1

1

Mod-high CPA/Mod high OPA

Abbreviations: LTPA, leisure-time physical activity; CPA, commuting physical activity; OPA, occupational physical activity. Note. Model 1 adjusted for age, smoking, and the remaining domain of physical activity. Model 2 adjusted for age, smoking, the remaining domain of physical activity, and waist circumference.

the normal range in all LTPA groups. Furthermore, the conclusions from the meta-analyses of randomized controlled trials suggest an evidence for the decreasing effect of exercise on blood pressure.56,57 No associations were found in the current study for clustered CVD risk or single risk factors between the OPA groups. This is in line with the results of Sisson et al21 and Mozumdar & Liguori.58 In addition, most previous studies have shown no associations with any CVD risk factors.20,21,58 However, an inverse association between OPA and blood pressure,9,19 and a positive association with HDLcholesterol9,19,22,59 and systolic blood pressure60 have been observed. Regarding the young age of participants in the current study, it seems

plausible that no association was found. It can be speculated that the working in a job including either high or low physical activity may not have had a sufficient time to interact with the CVD risk factors. In addition, for an individual it may be difficult to evaluate the mean physical demands of the work, especially in younger adults who are prone more often to have short-time and temporary jobs. The high LTPA group showed significantly better results in all physical fitness parameters and waist circumference, whereas high CPA showed better results in terms of cardiorespiratory fitness, some of the muscular endurance tests and waist circumference compared with other CPA groups. As LTPA can include a wide range of physi-

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Physical Activity and Cardiovascular Risk Factors in Young Men   1489

cal activity from endurance to power and strength as well as motor coordination, the findings seem plausible. Similar to the current study findings, Andersen et al27 found that aerobic power and muscular endurance were better in children cycling to school compared with those walking or using passive transportation. Moreover, high OPA was associated with better maximal isometric grip strength in line with previous studies,31,33,34 whereas some studies have also shown no association or inverse relationships.29,30 No difference in cardiorespiratory fitness was found between the OPA groups in this study, which is in line with most29,30,61 but not all previous studies.31 Engagement in either LTPA or CPA is therefore, also suggested for those individuals with high occupational activity. The strength of the current study is the extensive data set including physical fitness of both cardiorespiratory and dimensions of muscular fitness. However, there are some limitations to be considered. We used a subjective method (questionnaire) to assess physical activity, which may have led to reporting bias as noted previously.35 The self –administered questionnaires to assess physical activity may lead to under- or overestimation and may therefore be imprecise. Self-reported physical activity measures have also been shown to be prone to recall bias or influenced social desirability bias. Although acceptable to good reliability with selfreport instruments of assessing physical activity have been shown, the validity may be poor to moderate.36 However, as there is no gold standard for assessing physical activity, both self-report instruments and objective measurements and especially their combination are needed in population wide studies of physical activity.62 Although we addressed several confounding factors (age, smoking, other domains of physical activity and waist circumference), there are some factors that we could not account for (eg, nutrition, stress). Finally, due to the cross-sectional study design, causality of the relationships cannot be assessed.

Summary and Conclusions In conclusion, the current study demonstrated that low CPA alone was related to over 2 times higher likelihood for the higher continuous CVD risk factor score independent of other physical activity. In addition, the combination of low LTPA with either low CPA or low OPA was related to nearly 2 times higher likelihood for the continuous CVD risk factor score. These results emphasize the role of CPA and support the notion that avoiding physical inactivity in its different domains is beneficially related to the continuous CVD risk factor score in young adult men. Acknowledgments The authors thank all the test personnel for their work in data collection and M.Sc Elina Vaara, University of Jyväskylä for statistical guidance. This work was supported by a grant from the Scientific Advisory Board for Defence.

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