Sitting Interruption Modalities during Prolonged Sitting Acutely Improve Postprandial Metabolome in a Crossover Pilot Trial among Postmenopausal Women

Abstract

Older adults sit during most hours of the day; more than 30% are considered physically inactive. The accumulation of prolonged sitting time is an exercise-independent risk factor for aging-related conditions such as cardiometabolic disease and cancer. Archival plasma samples from a randomized controlled, four-condition crossover study conducted in 10 postmenopausal women with overweight or obesity were analyzed. During 5-hour conditions completed on separate days, the trial tested three interruption modalities: two-minute stands each 20 min (STS), hourly ten-minute standing breaks (Stand), hourly two-minute walks (Walk), and a controlled sit. Fasting baseline and 5-hour end point (2 h postprandial) samples were used for targeted metabolomic profiling. Condition-associated metabolome changes were compared using paired t-tests. STS eliminated the postprandial elevation of amino acid metabolites that was observed in the control. A norvaline derivative shown to have anti-hypertensive and -hyperglycemic effects was significantly increased during Stand and STS. Post-hoc testing identified 19 significantly different metabolites across the interventions. Tight metabolite clustering by condition was driven by amino acid, vasoactive, and sugar metabolites, as demonstrated by partial least squares-discriminant analyses. This exploratory study suggests that brief, low-intensity modalities of interrupting prolonged sitting can acutely elucidate beneficial cardiometabolic changes in postmenopausal women with cardiometabolic risk.

Keywords: 5-hydroxynorvaline; aging; anserine; aspartate; blood flow; endothelial function; glycemic control; postprandial metabolism; raffinose; sedentary behavior.

Figure 1

Schematic overview of clinic visits (A) and study protocol (B). Image adapted from figure shown in parent study paper [17].

Figure 2

Heatmap of condition-averaged metabolites that were significantly different between postprandial conditions (p < 0.05). The display demonstrates normalized relative increases and decreases in abundance between and within conditions in postmenopausal women. N = 10 for the Control, Stand, and Walk conditions; N = 9 for the STS condition.

Figure 3

Mean average box plots of 5-hydroxynorvaline and raffinose across all conditions by post/pre-condition ratio of relative abundance. Black dots represent participant post/pre-condition ratio and yellow diamonds denote mean ratio relative abundance of each condition. N = 10 for the Control, Stand, and Walk conditions; N = 9 for the STS condition.

Figure 4

Pathway enrichment analysis of the three interrupted sitting conditions against the controlled sit. Data are plotted as −log₁₀(p) versus pathway impact and darker color represent greater significant differences. N = 10 for the Control vs. Stand and Control vs. Walk conditions; N = 9 for the Control vs. STS condition.

Figure 5

Enzyme enrichment analysis of the three sitting interruption conditions compared to the Control condition. N = 10 for the Control vs. Stand and Control vs. Walk conditions; N = 9 for the Control vs. STS condition.

Figure 6

Orthogonal partial least squares-discriminant analysis (OPLS-DA) score plots (A) and variable importance projection (VIP) scores (B). A. OPLS-DA plots indicate discrete condition-specific postprandial metabolomes. B. VIP score-ranked metabolites indicate the most influential metabolites distinguishing the interrupted sitting modality from the Control in the OPLS-DA models. N = 10 for the Control vs. Stand and Control vs. Walk conditions; N = 9 for the Control vs. STS condition.