6633 
Regular, moderate intensity physical activity (MPA) leads to a reduction in mortality but a study has suggested that increasing the amount of vigorous physical activity offers additional health benefits.
It has been suggested that undertaking vigorous physical activity (VPA) might offer additional health benefits compared with MPA alone. However, what remains unclear is the amount of VPA which needs to be incorporated into any form of MPA to derive a mortality benefit. In this study, a team from the department of epidemiology and biostatistics, Wuhan, China, set out to retrospectively analysis data acquired from a national health interview survey (NHIS) conducted between 1997-2013, which included data on self-reported levels of physical activity and was linked to the national death index records through to the end of December 2015. The NHIS survey included questions looking at how frequently individuals undertook MPA, how long it lasted and whether this activity included any VPA that caused heavy sweating or a large increase in heart rate. The researchers calculated the amount of MPA undertaken and the proportion of VPA as a percentage of the total MPA. The outcomes of interest were mortality and divided into: all-cause mortality; cardiovascular disease and cancer mortality.
Findings
The sample included data on 403,681 individuals (51.7% female) with an average age of 42.8 years who were followed for a median of 10.1 years and over which time there were 36,861 deaths. The amount of VPA undertaken varied and just over a fifth (21.3%) of participants reported that VPA accounted for between 50 and 75% of their total physical activity. When compared to individuals performing no VPA, where VPA represented between 50 and 75% of all physical activity, there was a 17% reduction in all-cause mortality (hazard ratio, HR = 0.83, 95% CI 0.79-0.91, p < 0.001). Furthermore, there was also a significant reduction in the risk of cardiovascular (HR = 0.83) and cancer (HR = 0.80) mortality. Further increases in VPA did not lead to a greater reduction in either all-cause, cardiovascular or cancer mortality. With respect to duration, the results suggested that performing 150 to 299 minutes of MPA and 150 minutes or more of VPA had the lowest all-cause mortality risk. Commenting on these results, the authors suggested that public health message should be that individuals need to perform at least 150 minutes per week of MPA and that increasing the amount of VPA within this regime, leads to greater mortality benefits.
Citation Wang Yet al. Association of physical activity intensity with mortality.. A national cohort study of 402,681 US adults. JAMA Intern Med 2020 doi:10.1001/jamainternmed.2020.6331
