(C) PLOS One [1]. This unaltered content originally appeared in journals.plosone.org.
Licensed under Creative Commons Attribution (CC BY) license.
url:https://journals.plos.org/plosone/s/licenses-and-copyright

------------



The physical activity health paradox and risk factors for cardiovascular disease: A cross-sectional compositional data analysis in the Copenhagen City Heart Study

['Melker S. Johansson', 'Musculoskeletal Disorders', 'Physical Workload', 'National Research Centre For The Working Environment', 'Copenhagen', 'Department Of Sports Science', 'Clinical Biomechanics', 'University Of Southern Denmark', 'Odense', 'Andreas Holtermann']

Date: 2022-05

During leisure, the findings indicated less sedentary behaviour and more walking or more HIPA to be associated with a lower SBP, while during work, the findings indicated an association with a higher SBP. During both domains, the findings indicated that less sedentary behaviour and more HIPA was associated with a smaller WC and a lower LDL-C. Furthermore, the findings indicated less sedentary behaviour and more walking to be associated with a larger WC and a higher LDL-C, regardless of domain.

Interpretation of findings

Systolic blood pressure. During leisure, the results indicated less sedentary behaviour and more walking or more HIPA compared to the reference composition to be associated with a lower SBP. In contrast, during work, the results indicated an association with a higher SBP (Fig 2, Tables 3 and 4). Although not statistically significant, these findings support that these physical activity types can have either beneficial or detrimental associations with a CVD risk factor depending on domain [8,15]. Importantly, the results from the time reallocations should be seen relative to the reference composition (Table 2). These findings may be explained by differences in characteristics between physical activity during leisure and work [19]. Regular physical activity of moderate or higher intensity that takes place during relatively short time periods may, given sufficient time for restitution, facilitate beneficial central and peripheral adaptations of the cardiovascular system (e.g., lower heart rate, blood pressure, and inflammatory biomarkers), which decrease the risk of CVD. However, contextual factors and work conditions (e.g., productive demands, degree of control, heavy lifting, and awkward or static body postures) [15,19] make occupational physical activity different from physical activity during leisure with regards to the intensity, duration, and variation of the physical activity, as well as restitution [15,19]. Combinations of high occupational physical activity and insufficient restitution have been suggested to increase average daily heart rate, blood pressure, and levels of inflammatory biomarkers [13,15,19], which all increase the risk of CVD [19]. These mechanisms could explain our findings of a contrasting association between physical activity types during leisure and work, and SBP (Fig 2, Tables 3 and 4). As previously mentioned, measurement error (i.e., use of self-reported physical activity data) has also been suggested to explain the physical activity health paradox. Our findings do not support this since they are based on device-based measurements of physical activity. There is considerable evidence that leisure time physical activity has favourable effects on SBP [6,43–45], while sedentary behaviour during leisure seems to be weakly associated with SBP [46]. However, to our knowledge, fewer studies have investigated how occupational physical activity are associated with SBP, and their findings are inconclusive [13,47–53]. For example, among studies investigating both leisure time and occupational physical activity, two studies found an association between higher leisure time physical activity and a lower SBP [13,48], which is in agreement with the findings in this study (i.e., the reallocation of time from sedentary behaviour to walking or to HIPA during leisure). In addition, one study found higher leisure time physical activity to be associated with a higher SBP [51], while two other studies did not find any association [13,50]. The results in the current study disagree with these studies. On the other hand, our findings related to the reallocation of time from sedentary behaviour to walking or HIPA during work (i.e., indications of an association with a higher SBP) agree with three of these studies [13,52,53], but disagree with six other studies [13,47–51]; of which four did not find any association [13,49–51]. Only two of these previous studies used accelerometer data [13,48], and only one used CoDA [48]; the remaining studies used self-reported data and a ‘traditional’ analytical approach (i.e., did not take the co-dependency between physical activity types or intensities into account). Furthermore, all studies used general population samples, except three studies that used working populations [13,48,52]. Therefore, based on studies that have investigated how physical activity during both leisure and work are associated with SBP, the association between occupational physical activity and SBP is inconclusive. Our results indicated a 1.7 (95% CI: -0.8, 4.2) mm Hg higher SBP given 30 minutes less sedentary behaviour and 30 minutes more walking during work, and an 0.7 (95% CI: -2.6, 1.2) mm Hg lower SBP given the same time reallocation during leisure. Furthermore, 30 minutes less walking and 30 minutes more sedentary behaviour during work suggested a 6.7 (95% CI: -16.2, 2.9) mm Hg lower SBP. This difference is 11 times larger than that of the opposite reallocation during leisure (i.e., 30 min less sedentary behaviour and 30 min more walking: -0.7, 95% CI: -2.6, 1.2 mm Hg), and could be expected to reduce the risk of CVD-specific mortality by over 20% based on the known linear relationship between SBP and CVD [54,55]. Since even small changes in the population mean SBP can have substantial impact on CVD risk (i.e., affecting the prevalence of hypertension) [54–56], these findings could, potentially, have important implications in population-based prevention of CVD [44].

Waist circumference. During both domains, our results indicated less sedentary behaviour and more walking compared to the reference composition to be associated with a larger WC (Fig 3, Table 3). This finding may, potentially, be attributed to differences in occupation, socioeconomic status, and health, since low socioeconomic status is known to be associated with poor health [21], including overweight and dyslipidaemia [22]. That is, individuals with lower socioeconomic status who, in general, have poorer health are more likely to have occupations that involve little sedentary behaviour and high physical activity [18], such as long durations of walking. Further, we emphasise that the association between physical activity and overweight is bidirectional, and that other factors not considered in our analyses (e.g., diet) are influencing a person’s WC. Importantly, these findings highlight that our estimates represent measures of associations, and not causal effects [57]. Furthermore, we found less sedentary behaviour and more HIPA during leisure to be associated with a smaller WC (e.g., 10 min less sedentary and 10 min more HIPA: -1.35, 95% CI: -1.90, -0.80 cm; Fig 3, Table 4). The estimates during work followed the same pattern but were small and the CIs included zero. This is in line with existing evidence from observational and intervention studies [58–61]. The current findings also support that domain-specific characteristics of physical activity do not affect risk factors for which diet is most important [62–64]. In previous studies based on total or leisure time physical activity, less sedentary behaviour and more physical activity, in particular HIPA, is reported to be associated with lower WC [58]. The results for WC in the present study are in agreement with this (i.e., given the reallocation of time from sedentary behaviour to HIPA in both domains). However, to our knowledge, few studies have investigated how both leisure time and occupational physical activity are associated with WC [47,51–53,65–67]. Only two of these studies used accelerometer-data [66,67], and one used iso-temporal substitution modelling [67]; the remaining studies used self-reported data and ‘traditional’ analyses. None of these studies found contrasting associations between leisure and work, although some only found associations during one of the two domains [47,51,66]. In the current study, the reallocation of time from sedentary behaviour to walking during both domains seemed to be associated with a larger WC, which is incongruent with one previous study that did not find an association between less sedentary behaviour and more walking [67]. On the other hand, the results in our study indicated an association between less sedentary time and more HIPA and a smaller WC, which is in line with two previous studies [51,67]. Finally, in five studies that focussed on sedentary behaviour, the direction of the reported associations is varied, but the findings do not suggest that physical activity during leisure and work have contrasting associations with WC [47,52,53,65,66]. From a population-based prevention-perspective, even small shifts in the population mean of WC, such as the 1.4 cm smaller WC given 10 minutes less sedentary behaviour and 10 more minutes of HIPA during leisure, can have implications for public health, since it may decrease the prevalence of individuals at increased risk for CVD due to a high WC.

Low-density lipoprotein cholesterol. For LDL-C, during both domains the results indicated that less sedentary behaviour and more walking was associated with a higher LDL-C (Fig 4, Table 3). Similar to WC, and as previously discussed, one potential explanation to these findings may be confounding by socioeconomic status and occupation, which are linked to poor health [18,21,22]. Furthermore, during leisure and work, the results indicated that less sedentary behaviour and more HIPA was associated with a lower LDL-C (e.g., 10 minutes during leisure: -0.07, 95% CI: -0.12, -0.02 mmol/L; Fig 4, Table 4). This is in line with clinical guidelines, where leisure time physical activity is regarded to have a smaller effect on LDL-C (i.e., <5%) compared to, for example, high-density lipoprotein cholesterol (HDL-C) (i.e., >10%) [63]. These findings also support that differences in the characteristics of physical activity during leisure and work do not affect LDL-C differently. This is likely because LDL-C is mainly influenced by total energy expenditure, and not by type of physical activity, posture, or pattern of accumulation over time [62,63,68]. The results for LDL-C in the current study indicated different associations between the two reallocations but did not differ between domains (Fig 4, Tables 3 and 4). During both leisure and work, the reallocation of time from sedentary behaviour to walking suggested an association with a higher LDL-C. This is in agreement with one study only investigating occupational physical activity [49], but in disagreement with other studies that have investigated how sedentary behaviour or physical activity during both leisure and work is associated with LDL-C [51,52,65]. Furthermore, during both domains, less sedentary behaviour and more HIPA seemed to be associated with a lower LDL-C. This disagrees with findings from three studies [51,52,65], where similar associations were reported for sedentary behaviour during leisure but not for work (except for the study by Honda et al. [52] where indications of opposite associations during leisure and work are reported). All mentioned studies used self-reported data and ‘traditional’ analyses. Hence, given the results of our study and previous literature, the association between physical activity during leisure and work, and LDL-C is unclear. On a population-level, a 1 mmol/L lower non-HDL-C (i.e., total cholesterol minus HDL-C) has been reported to lower IHD-mortality by 30% [69]. This translates to 0.3% lower IHD-mortality for every 0.01 mmol/L lower LDL-C. Therefore, even small improvements in LDL-C on a population-level like those observed in the current study, could, in combination with improvements in other modifiable risk factors (e.g., poor diet, high SBP, obesity, smoking, high alcohol consumption, and others), likely contribute to the prevention of incident IHD [70,71]. However, the potentially detrimental association between less sedentary behaviour and more HIPA during work and SBP should be kept in mind.

[END]

[1] Url: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0267427

(C) Plos One. "Accelerating the publication of peer-reviewed science."
Licensed under Creative Commons Attribution (CC BY 4.0)
URL: https://creativecommons.org/licenses/by/4.0/


via Magical.Fish Gopher News Feeds:
gopher://magical.fish/1/feeds/news/plosone/

You are viewing proxied material from magical.fish. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.