Aerobic Exercise, Resistance Training and Mortality

The research support for regular exercise to be associated with reduced risk of death is growing.  However, there is limited research that focuses on effects of aerobic versus strengthen (resistance) training.  Additionally, there is limited data comparing mortality in those with and without a general medical condition. 

Schoenborn and Stommel recently published a study addressing these issues in teh American Journal of Preventive Medicine.  They examined a large sample of U.S. adults and assessed whether they met  the 2008 USDHHS Activity Guidelines for Americans:

• 150 minutes per week of moderate intensity aerobic activity
• OR 75 minutes per week of high intensity aerobic activity
• Encourage two days per week of weight training of 7 large muscle groups

The study examined exercise levels and mortality by linking data from the 1997-2004 National Health Interview Survey and death registry data from 1997-2006.  Mortality examined in groups with no chronic medical conditions compared to those with one or more medical conditions including: diabetes, hypertension, vascular problems, lung disease (asthma/bronchitis), one or more functional limitations (any difficulty walking, climbing steps, standing, sitting, stooping, reaching, grasping, or lifting/pulling or pushing large objects).

This study was informative because it looked at the effect of aerobic versus strength versus both aerobic and strength on mortality.  Additionally, it examined the effect of exercise on mortality in four age categories: 18 and younger, 18 to 44 years of age, 45 to 64 years of age and 65 and older age groups.

>The key findings from the study were:

• Strength training alone was not associated with decrease mortality risk
• Aerobic exercise was linked to reduced mortality risk aerobic exercise with over 150 minutes per week somewhat better than less than 150 minutes per week ( although going above 300 minutes per week did not correlate with additional mortality reduction)
• Among those meeting aerobic exercise guidelines, adding strengthening showed a trend for correlation with an additional beneficial  mortality effect
• Older adults  with one or more chronic conditions appeared to have the strongest association between exercise and lower mortality risk

The chart below summarizes the magnitude of association between exercise levels and lower mortality rates in those in the 45 to 64 age category and those aged 65 and older with one or more medical conditions.  To aid in interpretation of the numbers the SMR for those 65 and older with one medical condition meeting both aerobic and strengthening exercise guidelines was .52.  This means during follow up they were 48% (1-SMR) less likely to die than those not meeting exercise guidelines for either aerobic or strengthening types.

This study is a correlational study and not a prospective controlled trial so the data need to be interpreted cautiously.  It may be that individuals with chronic medical conditions die not because they don't exercise but because their illness is so severe they are unable to exercise.  Nevertheless, this study adds to our knowledge of the relative correlation of aerobic and resistance training and mortality.  Additionally, it suggests that exercise may have a significant beneficial role in older adults who have one or more medical conditions.

Figure by author adapted from data provided in manuscript.

Schoenborn, C., & Stommel, M. (2011). Adherence to the 2008 Adult Physical Activity Guidelines and Mortality Risk American Journal of Preventive Medicine, 40 (5), 514-521 DOI: 10.1016/j.amepre.2010.12.029