Using light bodyweight exercise to interrupt prolonged sitting can help preserve lower-limb vascular function, according to a study published in Vascular Medicine.
For the randomized, controlled cross-over trial, researchers enrolled healthy adults (N=20) aged 18-30 years at the Kawaguchiko town, Fuji-yoshida site, and Health Science University in Japan. Individuals were randomly assigned to participate in either 3 hours of uninterrupted sitting (control group) or sitting with interruptions every 20 minutes to do 1-minute half squats (experimental group). All participants experienced both conditions on differing days. At each visit, volunteers had been fasting for 12 hours and were assessed by blood pressure cuffs on the upper and lower extremities in a supine position 20 minutes prior to and after the task. An effect size (ES) of 0.5 was considered moderate and 0.8 large.
The participants were 50% women and had a mean age of 21±2 years with a body mass index (BMI) of 21.5±1.6.
During prolonged sitting, heart rate increased 6.6% (change, 4.0; 95% CI, 2.9-5.0 bpm; ES, 0.86; P =.170). Pulse pressure was decreased in the arms (change, -2.5; 95% CI, -3.8 to -1.1 mm Hg; ES, 0.41) and legs (change, -2.7; 95% CI, -5.1 to -0.3 mm Hg; ES, 0.24) during prolonged sitting. A significant interaction effect for calf circumference was observed (P <.001).
For brachial-ankle pulse wave velocity, there was a significant interaction for leg arterial stiffness index, in which during prolonged sitting leg arterial stiffness index increased by 15.6% (change, 18.7%; 95% CI, 12.1%-25.3%; ES, 0.63) and decreased by 9.9% (change, -11.9%; 95% CI, -18.5% to -5.3%; ES, 0.40) during the experimental condition.
During prolonged sitting, the area under the curve (AUC) for tissue oxygen saturation decreased by 18% (change, -321; 95% CI, -543 to -100; ES, 0.32) and increased during exercise by 32% (change, 588; 95% CI, 366-809; ES, 0.59). A similar interaction was observed for tissue oxygen saturation upslope, in which there was an 8.2% decrease when sitting and 114% increase during exercise (P <.001).
The association between macrovascular and microvascular function was weak and was likely influenced by the direction of change for features on the basis of condition.
This study may have been limited by the baseline habitual activity levels among study participants.
These data indicated that frequently breaking up sedentary behavior has the potential to improve lower-limb vascular function by altering arterial stiffness and tissue oxygen saturation. Additional studies are needed to formulate specific guidelines for best practices.
“Although national and international agencies now recognize the important health benefits of breaking up sedentary behavior, no specific guidelines are provided,” the study authors said. “The current findings help to fill this gap in knowledge by reporting that a simple strategy to interrupt prolonged sitting, using half squats, prevents declines in lower-extremity vascular function.”
Horiuchi M, Stoner L. Macrovascular and microvascular responses to prolonged sitting with and without bodyweight exercise interruptions: a randomized cross-over trial. Vasc Med. Published online November 23, 2021. doi:10.1177/1358863X211053381