To fill this knowledge vacuum, the researchers set out to examine the possible influence of weight training and aerobic exercises on the risk of death in older persons separately and together.
They drew from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). This study began in 1993 and comprises 154,897 men and women between the ages of 55 and 74 from ten different cancer centres in the United States.
In 2006, 104,002 of the participants were also asked if they had exercised with weights in the previous year, and if so, how frequently--anywhere from once a month to several times a week.
They were also quizzed on moderate and intense physical activity frequency and duration throughout the previous year.
Moderate intensity was defined as "exercise that produced a light sweat or raised your breathing and heart rate to moderately high levels," while severe activity was defined as "activity that produced a heavy perspiration or elevated your breathing and heart rate to very high levels."
Based on total weekly minutes of MVPA, four activity groups were formed: (1) inactive, 0 minutes; (2) insufficient aerobic MVPA, 1-149 minutes; (3) sufficient, 150+ minutes of moderate, or equivalently vigorous, activity; and (4) highly active, 301 or more minutes of moderate, or equivalently vigorous, activity.
The final study contained the responses of 99,713 people, 28,477 of whom died over an average of 912 years of monitoring. Their average age at the start of the monitoring period was 71, and their average body mass index (BMI) was 27.8 kg/m2, indicating that they were overweight.
Almost one-quarter (23 per cent) of respondents reported some weightlifting activity, and 16 per cent stated they exercised with weights one to six times per week. Nearly one-third (32 per cent) were aerobically active enough, meeting (24 per cent) or above (8 per cent) MVPA requirements.
Weight training and aerobic MVPA were both related to a lower risk of death from any cause, as well as cardiovascular disease, but not cancer.
Working out with weights was related to a 9-22 per cent lower risk of death in the absence of MVPA, depending on the amount: for example, using weights once or twice a week was connected with a 14 per cent lower risk.
Similarly, among those who did not exercise with weights, aerobic MVPA was linked to a 24-34 per cent decreased risk of death from any cause, compared to those who reported neither MVPA nor weight training.
However, those who reported doing both types of physical activity had the lowest risk of dying.
For example, those who stated they met the recommended weekly amounts of MVPA and exercised with weights once or twice a week had a 41-47 per cent lower risk of death than those who were physically sedentary.
Educational achievement, smoking, BMI, race, and ethnicity had no effect on the observed relationships, but gender did: the associations were higher in women.
This is an observational study, thus it cannot establish a cause, and it relies on personal recall and data from a single moment in time. There were no specific details on training intensity, training load, volume (sets and repetitions), or how long participants had been exercising with weights, which could have influenced the findings.
The study only employed weights, although the researchers include callisthenics (push-ups and squats), Pilates, and plyometric activities (tuck jumps and burpees) as other types of muscle strengthening exercises.
Weight training can help you lose weight: total lean mass is independently connected with a lower risk of death, according to the researchers as an explanation for their findings. And, if done in a gym, it might be quite sociable--yet another aspect linked to living a longer, better life.
"Our finding that individuals who participated in both types of exercise tended to have the lowest mortality risk provides strong support for current recommendations to engage in both aerobic and muscle-strengthening exercises," they write.
They conclude, "Older adults would certainly benefit from adding weightlifting activities to their physical activity programmes."