Regularly exercising with weights has been linked to a lower risk of death from any cause, with the exception of cancer, an international study has determined.
Ensuring a weekly exercise routine includes both weights and aerobic activities may also have an additive effect, the findings, published in the British Journal of Sports Medicine, suggest.
Current guidelines on physical activity for all adults recommend at least 150 minutes per week of moderately intense aerobic activity, or a minimum of 75 minutes of vigorously intense aerobic activity, or an equal combination of the two, usually referred to as MVPA (moderate to vigorous physical activity).
All adults are also recommended to incorporate activities that work the major muscle groups. Yet while aerobic exercise is consistently associated with a lower risk of death, it has long been unclear if working out with weights produces similar effects.
In a bid to plug this knowledge gap, the researchers set out to evaluate the potential impact of exercising with weights and aerobic activities on the risk of death among older adults.
To conduct their study, researchers from the University of Iowa drew on participants from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, a long-term cancer study. This began in 1993 and includes 154,897 men and women aged 55 to 74 from 10 different cancer centres in the United States.
In 2006, 104,002 of the participants were additionally asked if they had exercised with weights over the past year, and if so, how often they had done so; anything from less than once a month to several times a week.
They were also asked about the frequency and duration of both moderate and vigorous intensity physical activity over the past year. Moderate intensity was described as 'activity where you worked up a light sweat or increased your breathing and heart rate to moderately high levels', and vigorous activity as 'activity strenuous enough to work up a sweat or increase your breathing and heart rate to very high levels'.
Four activity groups were generated based on total weekly minutes of MVPA: (one) inactive, 0 minutes; (two) insufficient aerobic MVPA, 1–149 minutes; (three) sufficient, 150+ minutes of moderate, or an equivalent amount of vigorous, activity; and (four) highly active, 301 or more minutes of moderate, or an equivalent amount of vigorous, activity.
In all, the responses of 99,713 people were included in the final analysis, 28,477 of whom died over an average of 9.5 years of monitoring. Their average age at the start of the monitoring period was 71, and the average weight (BMI) was 27.8kg/m2, which is defined as overweight.
Nearly one in four (23 percent) respondents reported some weightlifting activity; 16 percent said they exercised with weights regularly between one to six times a week. Nearly a third (32 percent) were sufficiently aerobically active, either meeting (24 percent) or exceeding (8 percent) the guidelines on MVPA.
Exercising with weights and aerobic MVPA were both independently associated with a lower risk of death from any cause, as well as from cardiovascular disease - but not from cancer.
Overall, working out with weights in the absence of MVPA was associated with a 9 to 22 percent lower risk of death compared to those who didn't exercise, depending on the amount of weightlifting the person did; for example, using weights once or twice a week was associated with a 14 percent lower risk.
Similarly, among those who didn't exercise with weights, performing just moderate to vigorous cardio was also associated with a 24 to 35 percent lower risk of death from any cause, compared with those who reported neither MVPA nor exercising with weights.
However, the lowest risk of death was seen among those who said they performed both types of physical activity. For example, the risk of death was 41 to 47 percent lower among those who said they met most recommended weekly levels of MVPA and who exercised with weights once or twice a week than it was among those who were physically inactive.
Educational attainment, smoking, BMI, race and ethnicity didn't significantly change the associations observed, but sex did: the associations were stronger in women.
This is an observational study, and as such, cannot prove cause and effect; additionally it relied on personal recall and included data from a single point in time. Specific details on training intensity, training load, volume (sets and repetitions), and for how long participants had been exercising with weights weren't available, all of which may have influenced the findings. The study also focused solely on weights, but there are other types of muscle strengthening exercise, the researchers noted, citing callisthenics, which include push-ups and squats; Pilates; and plyometric exercises, which include tuck jumps and burpees.
However, the results of the study were still solid enough for the researchers to conclude that older adults would benefit from combining cardio and weights in their exercise routines.
Using weights can make a body leaner, and total lean mass is independently associated with a lower risk of death, they noted. And if done in a gym, could also be very sociable - another factor associated with a longer, healthier life.
"Our finding that mortality risk appeared to be lowest for those who participated in both types of exercise provides strong support for current recommendations to engage in both aerobic and muscle-strengthening activities," they wrote.
"Older adults would probably benefit from adding weightlifting exercises to their physical activity routines."
