10/06/2025
Motion is Lotion.
✅ Clinical Highlights: Physiology of Sedentary Behavior (SB)
▪️ Sedentary behavior (SB; time spent sitting) occupies a high proportion of adults’ waking hours, and its effects can be examined distinctly from a lack of exercise or physical activity (PA)
▪️ The average energy cost of common SBs generally ranges between 1.0 and 1.5 metabolic equivalent of task (MET).
• Energy expenditure, heart rate, skeletal muscle blood flow, and contractile activity are higher during sitting compared to reclining, but these measures are lower than in a standing position and during PA of any intensity.
▪️ Prolonged and uninterrupted SB leads to numerous adverse health outcomes, including:
• Insulin resistance
• Vascular dysfunction
• A shift in substrate use toward carbohydrate oxidation
• A shift in muscle fiber from oxidative to glycolytic type
• Reduced cardiorespiratory fitness
• Loss of muscle mass and strength and bone mass
• Increased total body fat mass, visceral fat depot, blood lipid concentrations, and inflammation
▪️ From a physiological standpoint, the impacts of SB relate to those caused by physical inactivity (i.e., too little exercise). However, high volumes of SB can still have adverse physiological impacts even when large volumes of aerobic and/or resistance exercise are performed.
▪️ Acutely, reducing/interrupting SB improves:
• Postprandial glucose and insulin responses
• Systolic blood pressure
• Mean arterial pressure
• Lower limb vascular function
In the longer term, small improvements are observed in:
• Body weight
• Waist circumference
• Percent body fat
• Fasting glucose
• HbA1c and HDL concentrations
• Systolic blood pressure
• Vascular function
Evidence for other health outcomes and physiological systems in the longer term is more limited.
▪️ While reducing/interrupting SB improves body composition, intermediary metabolism, and cardiovascular health outcomes, these effects are typically small, though marginally clinically meaningful.
👉 Since most studies have been conducted in healthy population groups (where outcomes are within normal ranges), larger effects may be observed in populations that are less healthy.
▪️ The focus of contemporary public health guidelines ("sit less, move more and exercise") is largely a consensus based primarily on epidemiological findings.
Further experimental evidence is required to clarify the physiological effects of interventions that combine exercise with SB reduction/interruption.
👉Nonetheless, reducing/interrupting SB is considered a low-risk strategy that holds clinical and population health relevance, and it can serve as a stepping stone toward regular participation in moderate-to-vigorous intensity PA.
⚠️Link To Article 👇
