Fitness, not physical activity, mitigates negative effects of prolonged sitting

Living a sedentary lifestyle – such as sitting for prolonged periods – has been shown to be a risk factor for cardiovascular disease and other conditions. Physical inactivity raises the risk of developing high blood pressure and coronary heart disease and has been found to increase the risk of certain cancers.

Studies have linked excessive sitting to being overweight and obese, type 2 diabetes, and early death. Lack of physical activity can also lead to feelings of anxiety and depression.

Sitting for long periods has been suggested to slow the metabolism, which affects the body’s ability to regulate blood sugar, blood pressure, and break down body fat.

Regular physical activity is essential for healthy aging, and adults aged 65 years and over gain substantial health benefits from regular exercise. Physical activity guidelines recommend older adults do at least 150 minutes of moderate-intensity aerobic activity per week, such as brisk walking, and muscle-strengthening activities on 2 or more days per week to work all major muscle groups.

Among individuals who meet physical activity recommendations, the risk of cardiovascular disease with high sedentary time remains. However, high levels of cardiorespiratory fitness are associated with reduced levels of cardiovascular risk factors, including high blood pressure, obesity, type 2 diabetes, and dyslipidemia.

Most active participants still spent 12-13 hours per day sedentary

Researchers from the Norwegian University of Science and Technology (NTNU) aimed to determine whether meeting physical activity guidelines or having high age-specific cardiorespiratory fitness would reduce the adverse effect of prolonged sitting on cardiovascular risk factors for seniors.

Cardiorespiratory fitness is the ability of the heart and lungs to provide the working muscles with oxygenated blood for a prolonged period and determine the level of fitness, which goes downhill with age. Cardiorespiratory fitness is an important health indicator that can predict cardiovascular disease mortality and can be improved by increasing both the intensity and amount of exercise.

While the average American adult sits for between 9-11 hours a day, the NTNU research found that the participants who were in the least sedentary third of the study still spent between 12-13 hours per day in sedentary behavior. The most sedentary of all participants were sedentary for up to 15 hours a day.

The NTNU study was part of a randomized controlled clinical trial with the primary objective of investigating the effect of exercise training on morbidity and mortality in the older adult population.

The team conducted a cross-sectional study of 495 women and 379 men from Norway aged between 70-77 years. Sedentary time and physical activity were assessed by accelerometers, while cardiorespiratory fitness was determined by peak oxygen uptake (VO2 peak) – the measurement of the volume of oxygen that the body can utilize during physical exertion.

Researchers compared different levels of activity with fitness levels and cardiovascular risk factor clusters. A cardiovascular risk factor cluster was defined as the presence of three to five risk factors for heart disease.

These risk factors included: elevated waist circumference, elevated blood triglycerides or reduced “good” cholesterol levels, high blood pressure or treatment for hypertension, and elevated fasting blood sugar levels – combined symptoms commonly referred to as metabolic syndrome.

High cardiorespiratory fitness reduced risk of heart disease

Findings – published in Mayo Clinic Proceedings – showed that when compared with women and men who were the least sedentary, women and men from the most sedentary group were 83 percent and 63 percent more likely to have cardiovascular risk factors from extended time sitting, respectively.

However, when the team took participants’ level of fitness into consideration – measured by having high age-specific cardiorespiratory fitness – they found that the fittest 40 percent had a decreased likelihood of cardiovascular risk factors from prolonged sitting.

This finding held true even though the fittest participants spent between 12-13 hours per day sedentary and did not meet current moderate to vigorous physical activity guidelines.

No decreased risk was observed in older adults who were physically active without being fit. Therefore, say the researchers, meeting physical activity guidelines alone does not eliminate the cardiovascular risks of sedentary behavior if individuals do not have a certain level of cardiorespiratory fitness.

“Our Western lifestyles necessarily involve a lot of sitting, and we spend more and more time sitting on average as we age. But our findings show that being fit plays an important part in successful aging and may lend protection against the negative health effects of being sedentary.”

First author Silvana Sandbakk

Regular physical exercise, even below the recommended guidelines, is beneficial to health and longevity. “However, it seems that fitness makes a difference for this age group and while we wait for more evidence, some physical activity in elders that improves fitness will go a long way,” Sandbakk concludes.

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