Data from the CARDIA study demonstrate that replacing sedentary time with light-intensity physical activity (LPA) is associated with improved cardiometabolic outcomes.

“Current PA guidelines support replacing sedentary time with PA of any intensity. Replacing sedentary time with LPA may be a more accessible behaviour change for many individuals compared with increasing moderate-to-vigorous PA (MVPA),” noted the study investigators, led by Dr Sylvia Badon from Kaiser Permanente Northern California, Pleasanton, California, US, in their poster presentation at EPI|Lifestyle 2025.

However, the longitudinal correlations between sedentary behaviour replacement and LPA and cardiometabolic health remain unclear. “We hypothesized that replacing time spent sedentary with LPA is associated with an improved cardiometabolic risk across midlife,” they said.

Badon and colleagues estimated changes in cardiometabolic risk score resulting from the replacement of sedentary time with LPA and whether associations differed by initial sedentary time or MVPA level. They evaluated 996 patients from the CARDIA prospective cohort study who had accelerometer and cardiometabolic biomarker data at years 20 (2005?2006) and 35 (2020?2022). Of these, 63 percent were women. The mean age was 45 years at year 20 and 60 years at year 35. [Epi|Lifestyle 2025, abstract P1119]

As the mean sedentary time increased across midlife, the LPA dropped. To illustrate, the mean sedentary time was 490 and 540 min/day at years 20 and 35, respectively. Between the two timepoints, the mean LPA dropped from 360 to 310 min/day, as did the mean MVPA (from 35 to 24 min/day).

As a result of the increased sedentary time and reduced LPA, the mean cardiometabolic risk score increased between years 20 and 35 (from ?0.073 to ?0.039).

Movement > inactivity = better outcomes

To explore the associations of reallocating up to 120 min between sedentary time and LPA from years 20 to 35 with change in cardiometabolic risk score between the two timepoints, the researchers used compositional isotemporal substitution models with four initial behaviour distributions: low sedentary time/low MVPA (4.66 hr sedentary, 10.21 hr LPA, 2 min MVPA), low sedentary time/high MVPA (4.66 hr sedentary, 9.74 hr LPA, 30 min MVPA), high sedentary time/low MVPA (9.31 hr sedentary, 5.55 hr LPA, 2 min MVPA), and high sedentary time/high MVPA (9.31 hr sedentary, 5.08 hr LPA, 20 min MVPA).

Among participants who initially had low sedentary time/low MVPA, the predicted difference in change in cardiometabolic risk score between years 20 and 35 was ?0.03 (95 percent confidence interval [CI], ?0.06 to ?0.003). This difference was mirrored in the low sedentary/high MVPA subset.

Among those who initially had high sedentary time/low MVPA, the association was attenuated and not statistically significant (?0.02, 95 percent CI, ?0.04 to 0.004). This effect was similarly observed in the high sedentary/high MVPA subset.

According to the researchers, the inverse associations were slightly stronger among those with low initial sedentary time.

The models were adjusted for age, sex, race, education, employment status, income, self-reported quality of life, health insurance status, smoking, alcohol use, and use of lipid, blood pressure, and diabetes medications.

Attenuates age-related decline

Participants were instructed to wear accelerometers ? the ActiGraph 7164 and wGT3X-BT ? at years 20 and 35, respectively, to assess sedentary behaviour and PA. The durations were averaged across valid days (10+ hr) and normalized to 15 hr.

The cardiometabolic score was determined by measuring waist circumference, mean arterial pressure, high-density lipoprotein cholesterol, triglycerides, glucose, and insulin, which were standardized using year 20 distributions and averaged to create a z-score. A higher cardiometabolic score indicated a worse score.

“[Our study showed that] hypothetical replacement of sedentary time with LPA was associated with the attenuation of age-related decline in cardiometabolic health across midlife, with slightly greater attenuation in those with initially low sedentary time,” the investigators concluded.