Prolonged Sitting: Worse Than Smoking? (Part 2)
Let’s continue exposing the latest evidence-based and peer-reviewed research.
Cancer Risks of Prolonged Sitting
Prolonged sitting has been identified as a significant risk factor for various types of cancer, with emerging research shedding light on its potential impact.[1] This association has been observed across multiple studies, pointing to a worrying correlation between sedentary lifestyles and the development of several forms of cancer.
— Types of Cancer Linked to Prolonged Sitting
Breast Cancer:
Women who spend extended periods sitting have been found to have a higher risk of developing breast cancer. Sedentary behaviour may influence hormone levels, inflammation, and insulin resistance, all of which can contribute to cancer development.
Colorectal Cancer:
Sitting for long periods has been linked to an increased risk of colorectal cancer. Physical inactivity can lead to slower intestinal transit times and prolonged exposure of the colon to carcinogens. Additionally, inflammation and insulin resistance associated with prolonged sitting can play a role in colorectal cancer development.
Lung Cancer:
Prolonged sitting has been associated with an elevated risk of lung cancer, independent of smoking status. The exact mechanisms are still being investigated, but chronic inflammation and changes in lung function due to inactivity might be contributing factors.
Prostate Cancer:
Men who lead sedentary lifestyles have shown higher rates of prostate cancer. The lack of physical activity might affect hormone levels and immune function, promoting cancerous growth in the prostate gland.
Endometrial Cancer:
Extended periods of sitting have been linked to an increased risk of endometrial cancer in women. Physical inactivity can influence hormone levels, particularly estrogen, which is known to play a significant role in the development of endometrial cancer.
Ovarian Cancer:
Sedentary behaviour is also associated with a higher risk of ovarian cancer. The mechanisms are not fully understood, but inflammation and metabolic disruptions caused by prolonged sitting might contribute to ovarian cancer risk.
“Prolonged TV viewing and time spent in other sedentary pursuits is associated with increased risks of certain types of cancer.”
— Mechanisms
Although the precise biological mechanisms linking prolonged sitting to cancer are still being studied, several plausible pathways have been identified:
Inflammation:
Prolonged sitting is associated with chronic low-grade inflammation. Elevated levels of inflammatory markers, such as C-reactive protein (CRP), have been found in individuals with sedentary lifestyles. Chronic inflammation is a known risk factor for cancer, as it can lead to DNA damage and promote tumour growth.
Insulin Resistance:
Sitting for extended periods can lead to insulin resistance, a condition where cells become less responsive to insulin. This can result in higher blood sugar levels and an increased risk of developing type 2 diabetes. Insulin resistance and high blood sugar levels have been linked to the development of various cancers.
Obesity:
Prolonged sitting contributes to weight gain and obesity, which are significant risk factors for several types of cancer. Excess body fat can produce hormones and growth factors that promote cancer cell growth. Additionally, obesity is associated with chronic inflammation and insulin resistance, further increasing cancer risk.
Hormonal Imbalances:
Physical inactivity can disrupt hormone levels, including estrogen, testosterone, and insulin. Hormonal imbalances can influence cancer development, particularly hormone-related cancers such as breast, prostate, and endometrial cancer.
Reduced Physical Activity:
Prolonged sitting often correlates with reduced overall physical activity. Physical activity helps regulate body weight, hormone levels, and immune function, all of which play crucial roles in cancer prevention. Lack of movement can lead to metabolic disturbances that increase cancer risk.
“Our findings revealed a causal link between the time spent watching television and an increased risk of pancreatic cancer.”
Upon discovering a direct link between chronic health conditions, physical inactivity, and sitting for long periods, it is clear that we need to reevaluate the role of our modern way of living on our bodies, our health and our mental well-being.
“Engaging in physical activity of any intensity is associated with reductions in colon and rectal cancer risk. Conversely, time spent sedentary is associated with increased colon cancer risk.”
Is Being More Active the Answer?
High levels of moderate-intensity physical activity (ie, about 60-75 min per day) seem to eliminate the increased risk of death associated with high sitting time. However, this high activity level attenuates but does not eliminate the increased risk associated with high TV viewing time. These results provide further evidence of the benefits of physical activity, particularly in societies where increasing numbers of people have to sit for long hours for work. (Ekelund, U. et al. 2016)
Another study echoes the same findings, concluding that their research demonstrates a dose-response association between sitting time and mortality from all causes and cardiovascular disease, independent of leisure time physical activity. (Katzmarzyk, PT. et al. 2009)
The point is not how often and how hard you exercise, but how often and how long you are sitting in your day.
Further studies examined the detrimental role of alcohol and tobacco smoking. They found that physical activity had little to no effect on individuals drinking alcohol regularly and those smoking — the strongest inverse association was found among those most active in both work and leisure. This means that the more you stress your body, the worse the health outcome.
To benefit from the health-supporting effect of medium-to-high physical activity, you must first allow your body to heal, repair, and balance immune and inflammatory responses. To do so, you must reduce your intake of alcohol and stop smoking.
What else could affect the outome?
Why being more active may not always improve outcomes:
Genetic Predisposition
It can limit the benefits of increased physical activity. Individuals with a family history of certain diseases, such as cardiovascular disease, diabetes, or cancer, may have a higher baseline risk that is not completely mitigated by physical activity alone. While exercise can reduce risk factors, it may not entirely overcome genetic influences.
Underlying Health Conditions
It may be challenging for people with chronic health conditions or disabilities to engage in regular physical activity. Conditions such as severe arthritis, chronic pain, or respiratory issues can limit one's ability to exercise effectively. In such cases, even a strong commitment to being active may not yield the same health benefits as it would for an otherwise healthy individual.
Poor Nutrition and Lifestyle Choices
Physical activity is just one component of a healthy lifestyle. Poor dietary choices, smoking, excessive alcohol consumption, and inadequate sleep can all counteract the benefits of exercise. For example, a diet high in processed foods and sugar can contribute to obesity and metabolic syndrome, regardless of physical activity levels. Thus, without a holistic approach to health, increased activity alone may not lead to significant improvements.
Environmental and Socioeconomic Factors
Access to safe spaces for exercise, financial resources, and time can all influence the ability to be physically active. Individuals living in areas with high crime rates, poor air quality, or lack of recreational facilities may find it challenging to exercise regularly. Additionally, socioeconomic factors such as long working hours, low income, and lack of access to health care can also impact the ability to maintain a healthy lifestyle.
Sedentary Behaviour Outside of Exercise
Even if you engage in regular physical activity, prolonged periods of sedentary behaviour can still pose health risks. For instance, someone might exercise vigorously for an hour but spend the rest of the day sitting at a desk or watching television. This pattern of behaviour can negate some of the benefits of exercise, as extended sitting is associated with adverse health outcomes such as cardiovascular disease, metabolic syndrome, and certain cancers.
Mental Health Barriers
Mental health issues, such as depression and anxiety, can significantly impact one’s motivation and ability to be physically active. These conditions can lead to fatigue, lack of energy, and diminished interest in once enjoyable activities, including exercise. Consequently, mental health support and treatment are essential components of any strategy to increase physical activity and improve overall health.
Ageing and Physical Limitations
As people age, their bodies naturally experience a decline in physical capabilities. Conditions such as osteoporosis, joint degeneration, and muscle loss can make it difficult to maintain the same levels of physical activity as in younger years. While staying active is important for ageing populations, the type and intensity of exercise may need to be adjusted to accommodate physical limitations, and the benefits may not be as pronounced as in younger, healthier individuals.
Lack of Personalised Exercise Programmes
Not all exercise is equally beneficial for everyone. Without a tailored approach that considers individual health status, fitness levels, and personal goals, people may not achieve optimal benefits from their physical activity. Generic exercise programmes may not address specific needs or limitations, leading to suboptimal outcomes.
You must push your body out of its comfort zone to have a greater impact on lean muscle tissue, metabolism and cellular function. To do so, vary your type of exercise and focus on strength training.
And remember: AVOID SITTING FOR LONG PERIOD. Find new ways to stand up, stretch or exercise whenever you can. e.g., take the stairs instead of the lift to reach the next floor, walk escalators instead of standing, walk around your office (also helps with inspiration and solution-finding, cycle to work, etc.), and walk outside to get or eat your lunch.
What other habits do you think may be suitable?
Comment below…
References:
1. Schmid, D. Leitzmann, MF. (2014). Television viewing and time spent sedentary in relation to cancer risk: A meta-analysis. Journal of the National Cancer Institute. 106(7), dju098. doi:10.1093/jnci/dju098
2. Gentiluomo, M. Dixon-Suen, SC. Farinella, R. et al. (2024). Physical activity, sedentary behavior, and pancreatic cancer risk: A mendelian randomization study. J Endocr Soc. 2024 Feb 29;8(4):bvae017. doi: 10.1210/jendso/bvae017. PMID: 38425433; PMCID: PMC10904288.
Friedenreich CM. (2001). Physical activity and cancer prevention: From observational to intervention research. Cancer Epidemiology, Biomarkers & Prevention. 10, pp. 287–301.
Garcia, L. Pearce, M. Abbas, A. et al. (2023). Non-occupational physical activity and risk of cardiovascular disease, cancer and mortality outcomes: A dose-response meta-analysis of large prospective studies. British Journal of Sports Medicine. 57(15), pp. 979-989. doi:10.1136/bjsports-2022-105669
Harriss, DJ. Cable, NT. George, K. et al. (2007). Physical activity before and after diagnosis of colorectal cancer: disease risk, clinical outcomes, response pathways and biomarkers. Sports Medicine. 37, pp. 947–960.
Howard, RA. Freedman, DM. Park, Y. et al. (2008). Physical activity, sedentary behavior, and the risk of colon and rectal cancer in the NIH-AARP Diet and Health Study. Cancer Causes & Control. 19(9), pp. 939-953. doi:10.1007/s10552-008-9159-0
Samad, AKA. Taylor, RS. Marshall, T. et al. (2005). A meta-analysis of the association of physical activity with reduced risk of colorectal cancer. Colorectal Diseases. 7, pp. 204–213.
Slattery, ML. (2004). Physical activity and colorectal cancer. Sports Medicine. 34, pp. 239–252.