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The Impact of Intensity Variation in Physical Activity on Mortality Rates

Jan 12, 2021
 
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Abdullah Al-Ajmi, PharmD Candidate, Skaggs School of Pharmacy and Pharmaceutical Sciences

Does a higher percentage of vigorous physical activity as part of total exercise time confer additional benefits? 

Exercise has been one of the critical recommendations for patients to improve their health and reduce morbidity and mortality. Many studies linked moderate-vigorous physical activity (MVPA) to improved health outcomes in patients. Different ranges of intensity have shown different levels of benefits. For example, some studies showed a reduction in cardiovascular risk with moderate physical activity (MPA) 90min/week. Therefore, guidelines recommend 150-300min/week of MPA. 

 

In contrast, in vigorous physical activity (VPA), guidelines recommend 75-150min/week. It is yet to be determined if VPA has additional benefit compared to MPA in the same total amount of MVPA. Previous studies compared VPA with MPA. However, the findings were inconclusive since some studies found that VPA is more beneficial in reducing mortality risk while others did not have the same outcome.  

This study aims to compare VPA with MPA, with a similar total MVPA amount, regarding their impact on all-cause mortality.  

The study was carried out as a retrospective analysis of public survey data. It included patients 18 or older who were randomly selected (one participant per home). Participants were interviewed to assess their health condition, lifestyle, and healthcare access. Data were from questionnaires between 1997-2013, with data included until December 2015 or death if it came first. Patients with missing information regarding physical activity or those who were disabled were excluded from the study. Similarly, patients who could not perform MPA or VPA and had cardiovascular disease (CVD) or cancer before enrolment were excluded.  

 Physical activity was evaluated based on the frequency of MPA and VPA. The intensity was based on patients’ responses to the interview questions about the rate of sweating (light or heavy) and breathing/heart rate in 10 minutes. The answer is then multiplied to calculate the weekly total. The outcomes were defined as mortality from CVD, cancer, or any other cause.  

Around 403,681 patients were included, 51.7% out of which were female. The average age was around 43 years, and the average follow-up period was about ten years. Approximately 7634 mortalities were from CVD causes, 8902 from cancer, and 20,325 from other causes. Most of the participants were females <45years of age with active alcohol consumption but who were nonsmokers. Some of the patients did not have MVPA (34.3%). The remaining 65.7% had MVPA. This group reported different rates of VPA. Around 32.5% reported 0% VPA while 10% reported 25-50% VPA. Approximately 21.3% reported a VPA of 50-75%, 15.2% reported 75-99% VPA, and 15.2% reported a 100% VPA, which included only VPA with no MPA component.  

The results showed that patients with a greater VPA rate had better all-cause mortality outcomes. After standardization, the reported all-cause mortality/10,000 patients were 96 in the 0% VPA group while 64.7 for the 50-75 patients, and in the 75-99% VPA it was around 64.1 with a hazard ratio (HR) 0.83 (95% CI, 0.83-0.88). It showed a reduction in all-cause mortality by 17% between 0% to 50-75%. The difference between 0% VPA to 75-99% had a HR of 0.85 (95% CI, 0.79-0.91). Similarly, high VPA portions were linked with lower mortality from CVD causes. A significant difference was reported in the >50-75% and >75-99%. Similar findings were reported in all the different subgroups.  

In terms of the MVPA, it was overall linked to a reduction in all-cause mortality and mortality from CVD and cancer. MPA results for 150-300min/week and VPA 75-150min/week compared to 0 minutes had the same rate of reduction in mortality rates.  

The finding showed that the best results were reported in the MPA 150-300min/week range and the VPA 150min/ week range for all-cause mortality.  Regarding mortality from CVD risk, up to 150min/week MPA and 150min/ week of VPA had the best mortality outcomes. Regarding cancer-related mortality, 300min/week of MPA and up to 75min/week of VPA had the best outcomes. These findings suggest that a combination of MPA and VPA with an increased VPA rate is generally linked to lower mortality risk except in cancer-related mortality, which showed better results in a higher rate of MPA and low VPA. Some of the study limitations include the presence of confounding variables.  The data does not explain the massive difference in mortality between the lower VPA rates (0-50%) compared to the smaller difference in the higher VPA ranges (50-99%). It may be attributed to other confounding variables that were not addressed in the study. 

Practice Pearls: 

  • Physical activity is associated with lower mortality risk. 
  • All-cause mortality is reduced significantly with a 50-75% and 75-99% VPA. 
  • Cancer-related mortality is reduced with higher MPA and a lower rate of VPA. 

 

Wang, Yafeng et al. Association of Physical Activity Intensity With Mortality: A National Cohort Study of 403 681 US Adults. JAMA internal medicine, e206331. 23 Nov. 2020, Accessed 8 Dec 2020. Available from: doi:10.1001/jamainternmed.2020.6331  

Wen, Chi Pang et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet (London, England) vol. 378,9798 (2011): 1244-53. doi:10.1016/S0140-6736(11)60749-6.  

 

Abdullah Al-Ajmi, PharmD Candidate, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences