An increase of physical activity can save your life — in more than just heart health.
Increase of physical activity is one of the leading recommendations in association to cardiovascular outcomes. An increase in physical activity is heavily associated with lowering risks of all cause mortality, cardiovascular disease (CVD), and certain cancers. However, as stated by Alexander Mok et al., 90% of the studies that produced our information on the links between physical activity and a reduction of CVD, cancer, and all-cause mortality risk are generated from observational studies. A certain concern for the procurement of the data has been raised by the authors of the article, because if the study is designed through an observational scope, there is only 1 point of reference (baseline) that researchers can compare to. Comparisons made to only the baseline measurement may over-simplify the complexities of the human lifestyle, since patients are prone to short term and long-term lifestyle modifications. The researchers of this article have made the distinction of measuring long term physical activity trajectories to baseline and subsequent measurements.
Using a detailed questionnaire with a reference time of the past year, the researchers compiled data on 14,599 men and women in the UK to measure their Physical Activity Energy Expenditure (PAEE). The baseline assessment took place between 1993 and 1997. There were 3 follow up questionnaires given, with the third and final questionnaire given 7.6 years after the baseline visit (standard deviation 0.9). Information on the covariates of the patients was collected at baseline and 3.6 years later by trained nurses. Covariates that were collected include smoking status, weight, blood pressure, social class, medical history, and more. Covariates were measured through the use of Cox Proportional Hazards Regression models to derive hazard ratios and to achieve a 95% confidence interval. Patient mortality follow up was conducted through the Office of National Statistics until March 31, 2016 using classifications set forth by the International Classification of Diseases 9th and 10th editions.
In this prospective cohort study, it was shown that an increase in physical activity trajectories was heavily linked to counteracting CVD, all-cause mortality, and certain cancers. Past levels of BMI, triglycerides, diet quality etc., did not affect the association between physical activity trajectories and the decrease of the various causes of mortality. Of the 14,599 participants at the first check in, 3148 deaths occurred (specifically, 950 from CVD and 1091 from cancer). In all models, lower mortality was associated with lower PAEE levels. For each difference of 10 kJ/kg/day between the participants of the study, hazard ratios were 0.70 (95% confidence interval 0.64 to 0.78) for all-cause mortality, 0.69 (0.57 to 0.83) for cardiovascular disease mortality, and 0.83 (0.70 to 0.98) for cancer mortality. When comparing participants who were ranked as consistently inactive to those who ranked as medium to high baseline physical activity and maintained such levels, it was found to decrease the risk of all cause mortality by 28% and 33% for medium and high ranked participants. Further analysis of those who decreased, maintained, and increased physical activity was conducted. When comparing to baseline, those who increased physical activity minimally were found to have a 24% decrease in mortality. Mortality rates were found to decrease in moderate and high increasers of physical activity at 38% and 42% respectively.
The researchers concluded that had the entire cohort remained inactive over the study design, a 24% increase in mortality would be observed. Patients at an increased risk of death were those in the medium-increaser and maintainer categories. There is a potential to prevent 93% of deaths associated with inactivity if 5 kJ/kg/day is met at the population level.
- Regardless of the measurements taken at baseline, a moderate or high increase in physical activity is inversely related to that of all cause mortality.
- Increasing activity by 5 and 10 kJ/kg/day has seen a decreased risk of 24% in all-cause mortality at the 5 and 10 year assessments.
- 5 kJ/kg/day is measured at 150 minutes per week of moderate intensity physical activity.
Mok, Alexander, et al. “Physical Activity Trajectories and Mortality: Population Based Cohort Study.” Bmj, 26 Apr. 2019, doi:10.1136/bmj.l2323.
Usif Darwish, PharmD Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences