Exercise Physiologist, Healthy Connections
Exercise Physiologist, Healthy Connections
Welcome back to part two of our sit less and move more blog! Let us do a quick recap of last week’s discussions. Sedentary behaviours such as prolonged sitting are independent risk factors for many chronic conditions and can result in:
So it’s clear that reducing the amount of time sitting is going to be beneficial for our health. But what is the best way to combat this issue? Does participating in physical activity lessen the health effects of sitting? Is standing that much better than sitting? Is a 60-minute walk enough to combat daily sitting?
These are the questions we hope to answer today!
We are aware that regular exercise has positive effects on our health (1). It has been recommended that we should aim to achieve at least 150 minutes of Moderate to Vigorous Physical Activity (MVPA)/week (5). Moderate to vigorous physical activity (MVPA) increases daily energy expenditure and decreases the risk of cardiovascular disease, metabolic disorders, and mortality (3).
You’re performing moderate activity if you can talk but can’t sing while doing an activity e.g. brisk walking. You’re performing vigorous activity if you can only say a few words while doing your activity e.g. repeated stair climbing.
Guess what? You can be achieving physical activity guidelines and still be considered sedentary. Research has shown that even after controlling for MVPA, people who excessively sit can still be at increased risk of poor health outcomes. For example, going for a brisk walk in the morning is not going to have a significant impact on your health if you spend the rest of the day sitting on the couch!
For those extra keen individuals who participate in high levels of MVPA e.g. 65-75 minutes of MVPA/day, they will likely have a marked reduction in the detrimental effects e.g. risk of mortality associated with prolonged sitting (1, 5). Unfortunately, only 45% of adults are participating in sufficient physical activity due to barriers e.g. lack of time, motivation, knowledge, or environmental factors. Therefore it seems important that we discuss ways to reduce high volumes of sitting time rather than trying to motivate everyone to start running daily (3, 4).
Substituting sitting with standing results in increased energy expenditure and has been associated with improved cardio-metabolic health outcomes. When standing there is an increase in circulation and muscle activity (10).
Standing results in an increase in heat production because more muscles are tensed and stretched to fight gravity and bear weight. Interestingly it has been shown that during 10 minutes of standing, the energy expenditure during the last 5 minutes was half of the first. This suggests that the initial change in posture is important and longer time spent standing may result in poor energy expenditure as sitting does (8,10).
Posture and Musculoskeletal Issues
Transitioning from sitting to standing places different pressures through the musculoskeletal system. Standing will counteract the tightnesses/weaknesses associated with prolonged sitting and reduce pressure on the spine. Breaking up sitting time with standing bouts every 30 minutes has been shown to reduce muscle discomfort and fatigue (12).
However, prolonged standing is associated with an increased risk of lower back pain, vascular problems, fatigue, and discomfort (1). During prolonged standing there is excessive contraction of the muscles involved in postural stability, and when standing with poor postures musculoskeletal issues can also arise (13). It has been suggested that to reduce the risk of developing musculoskeletal concerns, prolonged standing should be limited to approximately 40 minutes (2).
Due to an increase in physiological demand, standing results in improved blood flow and circulation throughout the body. Improved circulation and oxygen delivery has been linked to enhanced mental awareness, increased productivity and improved cardiovascular health (1, 13).
However, prolonged or “motionless” standing can cause poor venous (veins) blood flow and presents as lower limb swelling, increased varicose veins or leg pain. Muscle contractions of the lower limbs (calf muscles) helps pump lower extremity blood back to the heart (through veins). Prolonged standing causes a reduction in muscle contraction and therefore results in lower limb pooling and vascular issues (13).
Although it’s sometimes hard to step away from the computer screen or pause the TV episode, it is important to break up sitting time with some form of “activity break” whether that be standing or MVPA. A range of studies has found that different types of activity breaks (standing, light to moderate-intensity walking) were associated with greater metabolic outcomes, reduced muscular discomfort and reduced fatigue specifically for sedentary obese/overweight individuals (1, 12).
Light – Moderate Intensity Movement Breaks
Specifically performing repeated short bouts (<10 minutes) of light-moderate activity improves blood glucose (sugars), insulin, and triglyceride (fats) levels. These results were more evident when compared against standing breaks (11). Taking even smaller movement breaks (approx. 2 minutes) every 30 minutes of sitting has been shown to improve these health outcomes more so than performing a 30-minute walk before a bout of prolonged sitting (9 hours)(9).
For people who may already have cardio-metabolic risk factors or diseases, replacing sitting time with light physical activity can significantly reduce blood glucose, insulin, triglycerides, and blood pressure levels (7).
Vigorous Intensity Movement Breaks
For those individuals (I have been guilty of this) who perform short, high-intensity session in hope of it reversing the day of sitting …unfortunately this is not the case. Research has shown that performing low-volume, higher intensity sessions before a day of prolonged sitting showed no benefits with health markers (blood pressure, triglycerides & sugars) when compared to prolonged sitting with no exercise (6).
It is obvious that breaking up sitting time with regular movement breaks will result in improved health outcomes and reduce our risk of developing chronic conditions.
Struggling to think of some “activity break” ideas? Check out below to see Accredited Exercise Physiologist Sophie going through time-efficient workouts that you can perform to break up sedentary time.
In this video, Sophie provides you with four example routines of how to break up sitting time. Ideally, aim to stand up every 30 minutes of sitting and perform at least 2 minutes of movement. Each sample has two exercises, so try to perform each movement for 1 minute.
As a university-trained exercise physiologist, we use evidence from high-quality research studies to support our recommendations so many of these blogs will refer to research journal articles. If you would like to know more about this topic and the studies cited in this blog, please refer to the references below.