Key numbers
8116
Adults in the 1981 Canada Fitness Survey cohort
2.72
Relative risk of death, lowest vs highest sit-up quartile, men
2.26
Relative risk of death, lowest vs highest sit-up quartile, women
What the Canadian study measured
The clearest evidence here comes from 8116 people aged 20 to 69 who took part in the 1981 Canada Fitness Survey and were followed for 13 years. Sit-ups served as the measure of abdominal muscular endurance, alongside push-ups, grip strength and trunk flexibility. The analysis adjusted for age, smoking, body mass and estimated aerobic fitness (VO2max).
What it found
Sit-ups were the component most clearly linked to all-cause mortality. Compared with the highest quartile for their age and sex, people in the lowest quartile had a higher risk of death: a relative risk of 2.72 (95% CI 1.56 to 4.64) in men and 2.26 (95% CI 1.15 to 4.43) in women.
Push-ups and trunk flexibility showed no pattern of higher mortality across quartiles. Men with the lowest grip strength had a relative risk of 1.49, but its confidence interval (0.86 to 2.59) included no difference, so that result was not statistically significant. A null result is not proof that these capacities do not matter, and the push-up count used here is not the Systematic tempo push-up.
None of this shows that low endurance causes earlier death. An observational study like this one can show only that the two went together.
Two other cohorts
A Japanese study followed visitors to health-promotion centers for an average of 6.1 years after five physical tests at baseline, sit-ups among them. In men, lower scores on several tests went with a higher risk of death from all causes, for example a relative risk of 2.43 for the side step and 1.93 for sit-ups. Once the analysis adjusted for skinfold thickness, blood sugar, cholesterol, blood pressure, lung capacity and smoking, only side step, vertical jump and grip strength remained linked.
A 2026 study of community-dwelling Taiwanese adults aged 65 or older used seven fitness tests across four domains. People in the highest fifth for the 30-second chair stand had lower all-cause mortality than those in the lowest fifth (adjusted hazard ratio 0.55, 95% CI 0.46 to 0.65). That study counted the chair stand as a strength test, and its battery is different from the Systematic one.
The evidence
Each cited source is labeled according to how it supports the particular claim on this page. Direct test evidence, underlying-capacity findings and population reference values are distinguished from Systematic-defined protocols and standards. Historical development notes are retained internally rather than presented as public evidence. A study of an underlying capacity is never presented as validation of the Systematic test itself.
-
Underlying-capacity evidence New source
Katzmarzyk et al. (2002). Musculoskeletal fitness and risk of mortality. Medicine and science in sports and exercise.
What it found. In 8116 adults aged 20 to 69 followed for 13 years, the lowest quartile of sit-ups went with higher all-cause mortality than the highest, in men (relative risk 2.72) and women (2.26).
What it does not show. Push-ups and trunk flexibility showed no pattern, and the low-grip estimate in men (relative risk 1.49, 95% CI 0.86 to 2.59) was not statistically significant. It does not show cause.
-
Underlying-capacity evidence New source
Fujita et al. (1995). Physical-strength tests and mortality among visitors to health-promotion centers in Japan. Journal of clinical epidemiology.
What it found. In men, lower scores on several tests, sit-ups among them, went with excess all-cause mortality before adjustment.
What it does not show. After adjustment only side step, vertical jump and grip remained associated in men, and no comparable association was found in women. Vertical jump is not the broad jump.
-
Underlying-capacity evidence New source
Wu et al. (2026). Physical Fitness and All-Cause Mortality in Older Adults. JAMA network open.
What it found. In Taiwanese adults aged 65 or older, the highest versus lowest fifth of 30-second chair stand performance had lower all-cause mortality (adjusted hazard ratio 0.55, 95% CI 0.46 to 0.65).
What it does not show. Not all seven tests predicted mortality, the chair stand was counted as a strength test, and the battery does not validate Systematic's different one.
The Systematic Healthspan Assessment is a physical baseline. It is not a diagnosis, and it does not estimate a biological age, a disease risk or a lifespan.