What is the dose-response association of device-measured vigorous physical activity with mortality and the incidence of cardiovascular disease and cancer?

What is the dose-response association of device-measured vigorous physical activity with mortality and the incidence of cardiovascular disease and cancer?

In a recently published study in European Heart Journal Researchers showed the benefits of moderate amounts of vigorous physical activity (VPA) performed in short bouts to reduce the risk of heart disease and cancer.

Lernen: Starke körperliche Aktivität, Herzkrankheiten und Krebs: Wie wenig ist genug? Bildnachweis: Air Images/Shutterstock

background

The 2020 Physical Activity Guidelines for Americans (Second Edition) and World Health Organization (WHO) guidelines recommend 150 to 300 minutes of moderate-to-vigorous physical activity (MVPA) as a time-efficient replacement for regular exercise or achieving recommended physical activity levels.

Although based on prospective observational data, several studies have demonstrated the health benefits of VPA. For example, a recent study showed that when VPA accounts for 30 to 50% of total MVPA time, it reduces the risk of all-cause mortality (ACM) by ~10%. However, there is a lack of understanding about how much VPA (VPA volume) is required to improve health and reduce mortality and disease incidence, particularly cardiovascular diseases (CVDs) and cancer. In particular, device-based measurements are ideal for studying the dose response of short and intermittent VPA bursts.

About studying

In the present study, researchers enrolled 502629 participants in the age group of 40 to 69 years from the UK Biobank study between 2006 and 2010 to investigate the dose-response association of device-measured VPA with mortality and CVD and cancer incidence. They excluded participants with prevalent cardiovascular disease or cancer or who were diagnosed with such an event within the first 12 months of the milestone.

The team sent an Axivity AX3 accelerometer to 103,684 participants between 2013 and 2015. They initialized all devices to collect data with a sampling frequency of 100 hertz (Hz) and a dynamic range between ±8g. The team asked all participants to wear the AX3 accelerometers on their dominant wrist 24 hours a day for seven days to assess physical activity. They considered the beginning of the landmark period, marked by the time of the accelerometry measurements, as the beginning of the follow-up period.

As participants returned the devices, researchers calibrated their data and determined wear-free periods according to standard protocol. Only this data was analyzed or considered valid if participants wore the device for more than 16 hours. Additionally, each participant required at least four valid monitoring days, at least one of which was a weekend day, to be included in the study analysis.

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The study's physical activity scheme used features in the raw acceleration signal to quantify the time spent in different physical activities and their respective intensities in a 10-second window. The team calculated VPA volume for each participant by summing the time spent in each activity intensity band across all valid wear days. Notably, 96% of VPA volume occurred in bouts lasting up to two minutes.

Study outcomes included ACM, cardiovascular and cancer mortality, and cancer and cardiovascular incidence by VPA volume groups (no VPA to less than zero, 10, 30, 60 minutes per week, and ≥ 60 minutes per week). The team tracked all participants through October 31, 2021 for all outcome determinations. They used Poisson regression to calculate the absolute dose-response risk between VPA volume and each outcome and the Cox proportional hazard model to calculate hazard ratios (HRs).

Study results

The authors found a consistent nonlinear inverse correlation between VPA and all-cause and cancer mortality; however, the correlation between VPA and CVD mortality was of a linear dose-response type. Furthermore, there were comparable results for optimal and minimal dose-induced morbidity and mortality with a steep gradient for 5-year CVD incidence risk. The currently recommended 75 minutes of VPA per week was associated with the lowest risk in dose-response curves for all three mortality outcomes.

While 15 minutes of VPA per week reduced all-cause and cancer mortality by 16 to 18%, 20 minutes per week reduced CVD mortality risk by 40%. However, 53 minutes of VPA per week was associated with 36% lower ACM, with modest additional beneficial associations for more VPA. People with poor fitness or cardiovascular and cancer risk factors (e.g. obesity) who accumulated VPA in short bouts of up to two minutes (four times a day) reduced their risk of mortality by 27%.

Interestingly, the potentially beneficial VPA volume doses identified in the study were consistent across age, gender, and health risk factors. In this way, clinicians and health practitioners could encourage adults of all ages to participate in VPA for any length of time throughout the day and ensure their long-term engagement and adherence.

Conclusions

Previous questionnaire-based studies suggested that 60 to 70 minutes of VPA per week reduced the risk of mortality by 30%. Based on the device-based findings of the current study, at least 20 minutes of VPA per week resulted in a similarly low risk of mortality. Despite differences in constructs, the authors found a ∼3:1 equivalence in VPA time recorded by questionnaires and accelerometers.

Previous device-based studies measured physical activity at one-minute intervals (lower resolution). It may have masked short VPA durations and led to an underestimation of VPA volume. The current study used a higher resolution of physical activity (10 seconds) and found that 92% of VPA durations lasted one minute or less. Overall, the study results are very relevant from a clinical perspective, as time pressure remains the most frequently cited barrier to regular physical activity across age groups, genders, ethnicities and health conditions.

Reference:

• Ahmadi, M. et al. (2022) „Kräftige körperliche Aktivität, auftretende Herzerkrankungen und Krebs: Wie wenig ist genug?“, European Heart Journal. doi: 10.1093/eurheartj/ehac572. https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehac572/6771381?login=false

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