Strength and Survival: How Grip Strength Predicts Longevity in the 90+ Population

In a world where people often focus on staying fit and healthy for the years ahead, a recent study out of Brazil brings a powerful reminder that physical strength may be one of the most vital keys to longevity, especially in the oldest among us. Researchers undertook a massive investigation into the link between grip strength—a simple yet revealing measure of overall muscle strength—and survival rates in adults over the age of 90. The results were compelling: those with stronger grips were more likely to defy the odds, while those with weaker grips faced a greater risk of mortality. The study, involving nearly 2,000 nonagenarians, underscores an important truth that’s relevant to everyone: building and maintaining strength isn’t just for the young—it’s a life-saving habit that extends into our final years.

Ben

I’m back with another piece of interesting research that recently was published. Interesting not because of its conclusion, which is seemingly obvious for those who’ve lived a physically cultured life. But interesting because of the size of the study and age of the population studied. A group out of Brazil recently published an absolutely massive study that asked the simple question: how does strength impact death? More specifically, they were interested in the relationship a simple strength metric (handgrip dynamometry) has with all-cause mortality. And they did this in 1980 adults, men and women, over the age of 90. And about five years after the handgrip test, they circled back to see what survivor rates looked like.

This type of research is considered a prospective cohort study, which means the researchers measured a group of people (in this case, grip strength) and had an outcome in mind (all-cause mortality) that they were going to track over a certain time period (~5 years). When conducting this type of research, the outcome measure is what’s called a “hazard ratio”. That can be thought of as the likelihood that something occurs. In the case of this study, which the outcome measure was all-cause mortality, a hazard ratio of 1 would mean there is no association of grip strength with death. Anything greater than 1 is more likely to lead to the outcome, anything less than 1 is less likely to lead to the outcome. And it’s all percentage based with the difference from 1 being the percentage more or less likely. For instance, a hazard ratio of 1.3 is 30% more likely whereas a hazard ratio of 0.7 is 30% less likely to result in the outcome. There, now you know epidemiology.

So what did they find? For starters, they found the median grip strength for the men to be 26 kg (~57 lbs) and women to be 16 kg (~35 lbs). What kind of context does that fit into? Well, it’s tough to say. There’s no real standards for individuals this old. But, looking through some of my exercise physiology textbooks, I found the range of norms for ages 70-99 is 21.3-35.1 kg for men and 14.7-24.5 kg for women. So we could say they were probably average given that they were on the upper end of that age range. In terms of the associations they found, the researchers noted that those who were in the 90th percentile (meaning top 10% of strength) had a 25% less chance of dying (hazard ratio of 0.75). And, maybe more starkly, those who were in the 10th percentile (bottom 10% of strength) had a 27% greater chance of dying (33% for the men!). And the takeaway of the distribution of data was that there is no threshold of strength. For every bit stronger you can stay, there is a less likely chance you will succumb.

Now, one issue with these types of studies is that they have to sacrifice some level of control because there are so many subjects. The researchers did control for things like BMI, smoking status, and other variables that could be measured. But they couldn’t control for things like genetic predispositions, access to quality health care, or other dietary or physical activity factors that occurred over the 5 years between the test and follow-up. But, given that these individuals were all 90+ year olds, we could assume some degree of resilient and healthy living was present. And even if the actual percentages are off a bit due to confounding variables, the clear trend of strength benefiting longevity is there.

The big takeaway here is that the best day to start strength training was 20 years ago. If you missed that one, then the next best day is today. There are a lot of factors that play into health and longevity, and being strong certainly is one of them.