Researchers at Glasgow University, UK, found that the amount of leisure time spent watching a television or computer screen had almost double the impact on the risk of mortality, cardiovascular disease, and cancer in people with low grip strength or low fitness levels than on participants who had the highest levels of fitness and grip strength. Increasing strength and fitness may offset the adverse health consequences of spending a large proportion of leisure time sitting down and watching a screen, according to the authors.
The study1 shows that the risks associated with sedentary behavior are not the same for everyone; obviously, individuals with low physical activity experience the greatest adverse effects.
“This has potential implications for public health guidance as it suggests that specifically targeting people with low fitness and strength for interventions to reduce the time they spend sitting down may be an effective approach,” said Dr. Carlos Celis, corresponding author of the study.
As a Harvard Medical School study on grip strength confirmed, means more than just being able to deliver a firm handshake. A growing body of research points to grip being a predictor of one’s risk for having a heart attack or stroke or dying from cardiovascular disease. This study suggests measuring grip strength could be an efficient way to target individuals that may benefit most from public health interventions to reduce screen time instead of just making blanket suggestions that, frankly, haven’t done much to reduce the amount of time people spend staring at their phones.
General fitness testing can be difficult to scale and manage on a large scale, but grip strength is a quick, simple, and cheap measure, therefore it would be easy to implement as a screening tool in a variety of settings.
The Glasgow University study analyzed data from 391,089 participants from the UK Biobank, a large, prospective, population-based study that includes data on all-cause mortality, cardiovascular disease, and cancer incidence, along with screen time, grip strength, fitness and physical activity.
The researchers caution that the use of self-reported screen time and physical activity data may have impacted on the strength of the associations drawn in this study. The observational nature of the study does not allow for conclusions about cause and effect.
However, one novel finding of this study is that the associations between overall discretionary screen time—an index of TV viewing and leisure computing screen time—with all-cause mortality and cardiovascular disease and cancer incidence and mortality were substantially reduced by physical activity, cardiorespiratory fitness an, grip strength.
The results did not negate, overall, findings that higher levels of screen time are associated with a higher hazard for all-cause mortality, independent of physical activity, grip strength, BMI and other major confounding factors. However, the increased possibility of the various health risks associated with increasing screen time was almost twice as strong in those with low grip strength compared with high levels of grip strength. A similar pattern was observed for physical activity.
While not giving the fit and the strong a break from spending too much time on screens, the researchers suggest that people with the lowest levels of strength, fitness and physical activity could potentially obtain the greatest benefit from interventions aimed at reducing sedentary behaviors. This has significant value in helping the relevant authorities and health bodies in allocating resources to those most in need.
If you can crush walnuts between your thumb and forefinger, that buys you some time on the mortality scale but it’s probably okay to reduce your screen time, too.
1. Carlos A. Celis-Morales, Donald M. Lyall, Lewis Steell, Stuart R. Gray, Stamatina Iliodromiti, Jana Anderson, Daniel F. Mackay, Paul Welsh, Thomas Yates, Jill P. Pell, Naveed Sattar, Jason M. R. Gill. Associations of discretionary screen time with mortality, cardiovascular disease and cancer are attenuated by strength, fitness and physical activity: findings from the UK Biobank study. BMC Medicine, 2018; 16