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Healthy is as healthy does.

This is especially true when it comes to staying active as you get older. Even the simple act of getting out of your chair and walking around can improve your quality of life immeasurably over the short and long term.

The devastating effects of a sedentary lifestyle, particularly on cardiovascular health, have been made clear in two research papers published in the last year — one a clinical study involving over 90,000 participants in the UK and the other a meta-analysis of over 100 clinical studies investigating the effects of inactivity, prolonged daily sitting and sedentary lifestyles.

Inactivity and Cardiovascular Health

The majority of American adults spend more than half of their waking hours sitting. That's a conservative estimate. It's not hard to do, really. You drive to work, you sit at your desk all day, you eat lunch at your desk, you drive home, you spend a few hours in front of the TV. That's a lot of sitting. If you're in the minority, you get out to the gym a few days a week and get in some exercise. Still, in the grand scope of things, that's just a few hours taken away from a full-time job of just sitting around.

So what are the health outcomes, specifically for cardiovascular health, from all this chronic inactivity? How much activity is enough? Is there a point at which more activity offers little or no increased benefit? A new study from the UK, published in the journal PLOS Medicine in 2021, accessed a unique data resource to arrive at some pretty compelling conclusions.

One of the major drawbacks of clinical studies involving lifestyle variables -- especially in large groups of test subjects -- is that they rely on self-reported data as provided in questionnaire answers. Test subjects are notoriously inaccurate when reporting something as subjective as exercise. They can overestimate training volume and intensity during exercise while discounting entirely activity levels attained during other parts of the day.

Researchers have long intuited that there is an inverse relationship between physical activity and the occurrence of cardiovascular disease. That is, the more exercise you get, the less your risk of incurring cardiovascular disease. But there has always been uncertainty about the strength of this association because of the unreliability of the data.

From 2013 to 2015, an organization known as UK Biobank sought to improve the accuracy involved in measuring how active people really are. They placed accelerometers, small lightweight motion sensors, on the wrists of more than a half million people aged 40 through 69 and used them to more accurately measure the physical activity status of these test subjects.

In 2021, researchers isolated more than 90,000 participants in the Biobank co-hort (again, aged 40 to 69) who had no previous reports of cardiovascular disease at the time of the measurement and followed up on their medical history. They found that higher levels of physical activity were associated with lower risk for cardiovascular disease, and that this result was similar across total, moderate- and vigorous-intensity physical exercise.

Just as importantly, the researchers found that individuals who engaged in higher levels of physical activity had lower risk for cardiovascular disease throughout the range of physical activity measured. The lowest risk for cardiovascular disease in the UK Biobank cohort was seen at the highest level of physical activity, whether total, moderate-intensity, or vigorous-intensity. In conclusion the researchers noted that their findings "aligns with the recommendations of the UK Chief Medical Officer’s report on PA that 'some physical activity is good but more is better'." [1 Rema Ramakrishnan, et al]

A Meta-Analysis of Over 100 Studies Links Sedentary Habits to Several Markers of Cardiovascular Disease

Another ambitious recent scientific research paper, this one published in the journal Nature Reviews Cardiology in 2021, also takes a comprehensive view of the relationship between inactivity and poor cardiovascular outcomes, placing it in a broad perspective [2 David W. Dunstan, et al.]. This paper took the form of a meta-analysis of over 100 recent clinical studies investigating the effects of prolonged daily sitting and inactivity, and its results were eye-opening.

These researchers reaffirmed the validity of accumulating, highly informative evidence from prospective epidemiological studies documenting that long periods of time spent in sedentary behavior can lead to adverse health outcomes — particularly for cardiovascular disease. They then went on to break down individual mechanisms of sitting risk.

The researchers noted that vascular function is affected during prolonged periods of sitting, citing a meta-analysis of 17 studies showing that prolonged sitting led to an acute impairment of vascular function as measured by flow-mediated dilation. Another negative outcome of this reduced vascular function or "blood pooling" in large, lower-limb, weight-bearing muscles, is the reduction in metabolic demand and blood flow during prolonged sitting that is likely to contribute to acute increases in blood pressure. Studies suggest that the lower metabolic demand of sitting, coupled with reduced levels of vasodilatory metabolites, might lead to vasoconstriction in inactive muscles and, consequently, to increased peripheral resistance and mean arterial pressure.

Sitting-induced metabolic dysfunction can also have an effect on glucose levels in the blood, another key marker of potential cardiovascular stress. The researchers note that postprandial glucose, insulin and triacylglycerol levels in blood are acutely elevated after periods of prolonged sitting, while a meta-analysis of 37 studies showed that regular interruptions with physical activity during prolonged sitting had a significant beneficial effect by acutely reducing glucose and insulin levels compared with continuous sitting.

In addition, increased systemic inflammation caused by prolonged sitting can also increase the risk of cardiovascular disease. The researchers point out that extended periods of inactivity are detrimentally associated with levels of C-reactive protein and IL-6 in the plasma, indicators of chronic low-grade inflammation and oxidative stress. The authors also highlight negative effects on cerebral blood flow (as a result of blood pooling in the lower extremities) and sitting-induced "exercise resistance," which is the reduced capacity of your body to benefit -- over time -- in whatever amounts of physical activity you do participate in.

Sit Less and Move More

It should be emphasized here that the negative cardiovascular outcomes detailed above arise from an excess of daily cumulative hours of sitting and being sedentary. This means that, while exercise is important, it is not sufficient to sit around all day, then go all out in high-intensity exercise mode at the gym for 45 minutes (three times a week), then go back to being a couch potato. The key is to increase the total amount of overall activity in your day. This is particularly important for people over the age of 40. Observational evidence suggests that people start becoming less active as they enter their 40s and 50s -- exactly at the point where increased physical activity would do the most good.

The great thing about adopting a heart-smart lifestyle based on overall activity is that just about anything that isn't sitting counts. Including walking your dog. In fact, a recent paper published in the research journal BMC Public Health (3 Balin, et al) highlights the association between dog ownership and numerous healthy outcomes in terms of daily walking and activity.

There are so many terrific ways to exercise and just one boring way to sit. Take a walk on the beach. Work in your garden. Fly a kite. Take up yoga. Increase your one-rep max in the bench press. Go bird watching. Ride a bicycle. Run sprints up stadium stairs. It all counts, and it all helps to decrease your risk of cardiovascular disease, while improving your quality of life. The key is to find something you like and make it an alternative to chronic inactivity and a sedentary lifestyle.

Conclusion

Many of our readers here at ProSource.net are already highly active individuals, enjoying the health benefits of weight training, cardio exercise, and competitive sports. Many are younger people. And that’s all good. The point here is that physical activity in all its forms is and should be a lifetime pursuit. Not just for now, but into your 40s, 50s, 60s, and beyond. The benefits in terms of quality of life are immeasurable. And it’s truly amazing just how little it takes to get so much in return.


Scientific References

1 Rema Ramakrishnan, Aiden Doherty, Karl Smith-Byrne, Kazem Rahimi, Derrick Bennett, Mark Woodward, Rosemary Walmsley, Terence Dwyer. Accelerometer measured physical activity and the incidence of cardiovascular disease: Evidence from the UK Biobank cohort study. PLOS Medicine, January 12, 2021.

2 David W. Dunstan, Shilpa Dogra, Sophie E. Carter & Neville Owen. Sit less and move more for cardiovascular health: Emerging insights and opportunities. Nature Reviews Cardiology, Volume 18, pages 637–648 (2021).

3 Marcel Ballin, Oskar Antonsson, Viktor Rosenqvist, Peter Nordström & Anna Nordström. Association of dog ownership with accelerometer-measured physical activity and daily steps in 70-year-old individuals: a population-based cross-sectional study. BMC Public Health volume 21, Article number 2313, 21 December 2021.



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