Multimorbidity and leisure-time physical activity over the life course: a population-based birth cohort study

Multimorbidity, defined as the co-occurrence of two or more chronic conditions in the same individual [1], affects adults from all age groups, and its burden increases with aging [2]. It is associated with diminished quality of life of both individuals and their families [3]. Likewise, people with multimorbidity have higher frequency of hospitalizations [4, 5], which are usually followed by decreased functional capacity, cognitive function, and increased use of prescribed medications [6]. One important clinical aspect of multimorbidity is its multifactorial etiology. The chronic conditions that are affecting the same individual simultaneously are related to an impairment on different organic systems, which may lead to higher risk of disability and mortality [7‐9]. Also, the burden of multimorbidity for the patient is increased when primary care systems fail to appropriately address the needs of these patients [9, 10].

Moreover, multimorbidity is associated with increased risk of all-cause mortality in a dose-response effect [11] regardless of age, gender, and economic stratus [12]. Therefore, investigations about how lifestyle factors through life course could be associated with multimorbidity in older ages should be encouraged. Physical activity should be considered an alternative that deserves attention and investment, given its benefits on prevention and treatment of several noncommunicable chronic diseases [13].

Physical activity can be divided into four domains: leisure-time, occupational, commuting, and household activities. Leisure-time physical activity (LTPA) is related to physical activities performed during spare hours or leisure periods, based on individual or collective preferences. LTPDA has been shown an inverse relationship with all-cause, specific-cause mortality [14], and unhealthy ageing (i.e., ageing with no chronic conditions, cognitive impairment, and physical dependency) [15]. However, it is still scantly explored whether (and at which extent) LTPA in early ages or over different life stages could be associated with different rates of non-communicable disease in later life. Our hypothesis is that people who were physically active in early life stages would have a lower risk for multimorbidity than those with low physical activity practice.

Thus, the present study aimed to assess whether there is an association of LTPA at different stages of life with multimorbidity at age 55 and evaluate its cumulative effect during the early life stages on multimorbidity in middle-to-older adults.

From the initial sample of 18,558 cohort members, 9137 (49.2%) were interviewed in the latest sweep. Excluded participants were more likely to be male (54.8%), have no academic qualification (36.8%), be divorced/separated (24.7%), unemployed (16.5%), and smoker at age 50 (35.9%), as shown in Supplementary Table S2. Most included individuals were born in England (83.5%), female (51.5%), and white (97.8%) (Table 1). At age 55, 27.4% had at least a university or equivalent degree, while 69.9% were married or lived with a partner. Although more men were overweight or obese (71.3%; p < 0.001), alcohol intake were higher among women (p < 0.001).

Our analysis did not detect difference in LTPA between gender (p = 0.087), however, men reported higher work-related physical activity than women (p < 0.001). In addition, 80% of sample self-rated their health as good to excellent with no detectable difference between gender (p = 0.071).

Men were more physically active than women in age 11, 16, and 23 (p < 0.001; Table 2). The proportion of women who engage in in LTPA all days in the week was higher in age 33, 42, and 50. (p < 0.001).

From the 8414 participants who reported data about all included morbidities at age 55, 2278 (33.0%) were classified as having multimorbidity. Multimorbidity was more likely among participants with low educational achievement, at lowest quintile interval of income, who were not regular drinkers of alcoholic beverages, and with worse general health perception, as shown in Supplementary Table S3.

Table 3 exhibits results from log-likelihood ratio test to examine which life course model best described the association between LTPA through the life course and multimorbidity. We compared the fit of a series of nested logistic models (critical, accumulation or sensitive period models) with a fully saturated model. Critical periods of LTPA during childhood and adulthood provided an inferior fit compared to the saturated model (p < 0.001). However, critical period model for LTPA during adolescence (p > 0.99) and sensitive model (p > 0.99) provided a fit not worse than saturated model with no clear difference between models based on p-value, log-likelihood, and AIC. Accumulation models provided similar fit compared to saturated model (p > 0.99); however, AIC values were higher than observed in adolescence as a critical period and the sensitive model, as shown in Table 3. Therefore, adolescence as a critical period and the sensitive models were chosen as the two simplest models that best explained the association between LTPA through life stages and the risk of multimorbidity at age 55.

As shown in Table 4, LTPA during adolescence was associated with lower odds for multimorbidity at age 55 (OR: 0.82; 95%CI: 0.70; 0.97) independently of LTPA performed in other stages of life. Based on the sensitive model, being physically active during leisure time at adolescence (OR: 0.83; 95%CI: 0.70; 0.98) and middle-to-late adult life (ages 50 and 55) (OR:0.82; 95%CI: 0.69; 0.98) also promoted a protective effect against multimorbidity at age 55.

Our findings confirmed our hypothesis that engage in LTPA through life would reduce the risk for multimorbidity in older ages. Both sensitive and critical periods best explained the association between LTPA through life course and multimorbidity. We revealed that being physically active at adolescence and middle-to-late adult life reduced in about 17 and 18% the odds of multimorbidity at age 55, respectively, even when controlled for LTPA at all other analyzed ages. Similarly, engage in LTPA early in life was revealed as a critical period for decreasing the odds of multimorbidity at age 55.

Adolescence is an important life period where healthy lifestyle promotion (e.g. LTPA) could reduce the risk for some conditions such as obesity [23, 24], diabetes [25], and cognitive impairment [26] in older ages. Nevertheless, physical inactivity is predominant among children and adolescents aged between 6 and 15 years [27‐29]. This scenario seems to be associated with additional health-related events over the next decades, turning out also to be related to the prevalence of multimorbidity [11]. Given the burden on healthcare systems, that are already poised by elevated prevalence of those conditions [2], it is important to consider physical activity as a continued lifetime strategy for disease prevention instead of a solely rehabilitative method at advanced ages.

In a retrospective study conducted by Fernandes and Zanesco [25], physical activity at childhood (7 to 10 years) and adolescence (11 to 17 years) were related to a decreased risk for arterial hypertension and diabetes in adulthood (18 or more years). In our study, we observed that LTPA at adolescence was associated with odds reduction for multimorbidity at age 55 in the final adjusted model. The fact that this association was statistically significant in model 3 (adjusted for smoking, alcohol intake, and hours of sleep at middle-to-late adult life) show the importance of adolescence as a critical period for reducing the risk of multimorbidity in later life. Taken together, these previous findings support the notion of a protective physical activity “legacy” at early ages of childhood against multimorbidity at older ages. As this population is on school ages, the development of multicomponent school-based interventions promoting healthy lifestyle should be encouraged in order to reduce the likelihood of being affected by multimorbidity [30]. This scenario could also result in an increased quality of life and decreased the burden of multimorbidity in healthcare systems [31, 32].

Physical activity engagement in practice adulthood has been associated with reduced risk for chronic diseases and all-cause mortality [13]. Based on data from the English Longitudinal Study of Aging, Hamer et al. [15] reported that from a sample of older adults aged 50 or more, those who were physically inactive at baseline and became active at older ages had higher odds to have healthier aging than those who remained inactive. Similarly, we reported that LTPA at middle-to-late adult life (ages 50 and 55) had a significant protective effect against multimorbidity at age 55. Although the World Health Organization [33] recommends 150 min per week of moderate-to-vigorous physical activity, some studies have shown that lower levels could lead to reduced risk for chronic diseases and all-cause mortality. In this regard, Ekelund et al. [34, 35] revealed that lower doses of moderate-to-vigorous physical activity (i.e., 24 min per day) could contribute to the risk reduction of premature mortality, with a dose-response pattern in adulthood (20 years or more).

Dregan et al. [26] reported that LTPA sustained through life periods improved cognitive function in older adults. Another study [15] showed that becoming physically active at age 50 was associated with a lower risk for depression symptoms, cognitive impairment, and functional disability at older ages (8-year follow-up). Even though our results corroborate previous findings, cumulative models did not provide a sufficient explanation of the effect of LTPA during life course in multimorbidity. However, we highlight that, whenever feasible, LTPA must be promoted in all age groups especially among those groups with a higher prevalence of physical inactivity (children, adolescents, and older adults) [27, 36, 37]. Interventions tailored from those groups are necessary in order to prevent in the future a scenario with an even higher prevalence of multimorbidity and its burden on the healthcare system [38‐41].

Some limitations of this present study must be acknowledged. First, LTPA was measured by questionnaires. In order to reduce the bias from that measurement, we chose to use in our study only those sweeps with face-to-face interview administrated questionnaire. The 1958 National Child Development Survey is one of the oldest national-based cohort studies, so although the level of LTPA was not examined by devices-based measurements, the information from those sweeps are reliable, comparable, and relevant [20]. Also, as the instrument does not provide details about the weekly volume of LTPA, it was not possible to categorize participants based on the World Health Organization’s guidelines of physical activity. However, the operationalization for LTPA to categorize individuals as physically active or inactive was based on previously published studies from the same birth cohort [20, 42]. Second, participants with multimorbidity were more likely to have no academic qualification and be at the lowest quintile of income, so residual confounding cannot be ruled out. Also, there were no data available on the participants’ family history regarding chronic diseases. Third, although the loss to follow-up may be interpreted as a source of selection bias, the NCDS cohort remains largely representative of the sample that it was drawn with a response rate of sweep (58.5%) [43]. Furthermore, we used multiple imputations to avoid further reductions in the sample due to missing information [22]. Four, although data from other chronic diseases such as stroke were not available, the chronic conditions we considered to identify multimorbidity were highly prevalent among adults aged between 50 and 54 years-old in the United Kingdom in 2019 such as low back pain (18.2%), hearing impairment (17.5%), and diabetes (13.2%) [44]. Fifth, reversal causality cannot be ruled out especially regarding the protective effect of LTPA at age 55 against multimorbidity at the same age.

In conclusion, we identified LTPA during adolescence as a critical period associated with reduced risk for multimorbidity in late adult life. Similar protective status was found in the sensitive model for LTPA during the same period and in middle-to-late adulthood (ages 50 and 55). Although analysis of factors associated with the outcome along lifetime is complex and should be carefully interpreted, our results support the need for LTPA promotion through intervention tailored especially on schooling age and older ages to reduce the burden of multimorbidity.