Researchers who followed more than 147,000 adults for up to 30 years found that moderate strength training was associated with a lower risk of death, and that combining it with aerobic exercise improved overall survival rates the most.
Study: Long-term resistance training considering all-cause and cause-specific mortality: assessing dose-response and co-association with aerobic physical activity. Image credit: Arsenii Palivoda/Shutterstock.com
In recent research, British Journal of Sports Medicine They investigated whether resistance training alone or in combination with aerobic exercise affected all-cause and cause-specific mortality rates.
Effects of aerobic training and strength training
Aerobic exercise, such as walking, running, and cycling, is well established to improve cardiovascular health, increase endurance, and reduce the risk of chronic disease and mortality. In contrast, the long-term benefits of resistance training are less clear.
Guidelines recommend 150 to 300 minutes of moderate aerobic exercise or 75 to 150 minutes of vigorous aerobic exercise per week, plus at least two strength-strengthening activities per week. There is also evidence that resistance training more than once per week is associated with lower mortality, but this may not fully capture the effect of training volume.
Recent data suggests that strength training has a J-shaped relationship. Approximately 40 minutes per week is the lowest risk, and effectiveness decreases as the amount increases. Many studies evaluate resistance training only at baseline, which can introduce measurement error and limit understanding of long-term effects.
Research on how aerobic and strength training work together to impact mortality remains limited. Most research shows that combining both provides the greatest benefits, but resistance training alone may not provide additional survival benefits, especially when aerobic fitness is low. This distinction is important for public health recommendations.
Tracking strength training and mortality over time
The current study examined three major U.S. cohorts: the Health Professionals Follow-up Study (HPFS), the Nurses’ Health Study (NHS), and the Nurses’ Health Study II (NHSII), followed for more than 30 years to analyze how weekly strength training and aerobic exercise are associated with all-cause and cause-specific mortality. These cohorts enrolled more than 289,000 U.S. health care professionals and nurses from the late 1970s to the late 1980s.
After excluding history of cancer (excluding non-melanoma skin cancer), heart disease, stroke, missing age data, or withdrawal of consent, 147,374 participants (31,540 men and 115,834 women) were considered. Regular biennial updates and follow-up rates of >90% ensured reliable and up-to-date assessment of exposures and outcomes.
Resistance and aerobic fitness were assessed using self-report questionnaires administered every 2 to 4 years. Participants indicated the average amount of time per week they spent on activities such as weight training, walking, running, cycling, and other aerobic exercise. Weekly duration and intensity were used to calculate a cumulative average reflecting long-term activity patterns. Validation studies demonstrated good reliability and accuracy of these measurements.
Deaths and causes of death were determined based on medical records, death certificates, and national registries with over 98% certainty. Covariates considered in this study included race, age, weight, menopausal status, smoking, family history, body mass index (BMI), alcohol intake, total calories, and diet quality, which were updated regularly and modeled as time-varying variables.
Combining exercise habits has the lowest risk of death
The median age of participants was 54 years. Researchers observed that people who did more resistance training were generally younger, had a lower BMI, smoked less, ate healthier diets, and were more aerobically active than those who didn’t do resistance training.
During the follow-up period, 74% achieved more than 7.5 metabolic equivalent (MET) hours of aerobic activity per week and 46% participated in some form of strength training. Resistance training was least frequent among those with low aerobic fitness, but increased as aerobic fitness increased. A moderate positive association between resistance and aerobic exercise was observed.
With up to 30 years of follow-up, a total of 35,798 people died. People who did 90 to 119 minutes of strength training per week had a 13% lower risk of dying from any cause. However, those who went for more than 120 minutes did not receive any additional benefits. This protective association remained even after accounting for BMI.
For heart disease, 90 to 119 minutes of resistance training per week reduced the risk by 19%, and the effect was only slightly influenced by BMI. For cancer, the most significant risk reduction was between 1 and 59 minutes per week. Supplementary analyzes suggested that this pattern may be driven primarily by lower mortality from colorectal, bladder, and breast cancer, although the number of cases was small.
Resistance training for 90 to 119 minutes per week was also associated with a 27% lower risk of death from neurological disease. The authors noted that these findings should be interpreted with caution because neurodegenerative diseases can develop over decades and cause of death classification may be incomplete.
These findings were consistent in both men and women, even after the first 8 years of follow-up. This association was generally similar across groups defined by BMI, age, and diet quality. The protective effect was most pronounced among people who had never smoked or quit smoking more than 10 years ago. Although the number of cases was limited, resistance training was also associated with lower mortality in people younger than 55 years.
When both strength training and aerobic exercise were taken into account, people who did some strength training but little aerobic exercise had a slightly lower risk of death than those who did neither. However, meeting aerobic exercise guidelines significantly reduced mortality rates.
The lowest risk was observed in individuals who performed high levels of both aerobic and strength training, or very high levels of aerobic exercise alone. This trend was also consistent for deaths from heart disease, cancer, and neurological diseases. Importantly, low levels of resistance and aerobic fitness do not increase risk any more than low levels of either, indicating that there is no extra harm in the absence of both.
Training with moderate loads provides maximum benefits
The current study highlights that both moderate strength training and aerobic training are associated with reduced all-cause mortality, with the greatest benefits seen when both are performed at high levels.
However, more than 120 minutes of strength training per week was not associated with an additional reduction in mortality. Similarly, among people with very high levels of aerobic exercise, adding more resistance training did not lead to further reductions in mortality risk.
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