In relation to the title of this post, it is more accurate to say that a 35 year old British woman who is in the 90th percentile, at 39 kg, would be at the 10th percentile in 35 year old British men. But she would be at the 50th percentile for a 70 year old man. Another way to look at it is that an average 35 year old woman is as strong as an average 80 year old man.
Also of interest, 90 year old men have stronger grip strength than 10 year old boys (25 kg vs. 17 kgs) but 90 year old women have weaker grip strength than 10 year old girls (14 kg vs. 16 kgs). There is a major difference in life trajectory. Men and women start off with the same upper body strength as boys and girls in elementary school. But between ages 10 and 30 years men really outpace women.
Here’s a chart I constructed from the data with male an female at 10th, 50th, and 90th, percentiles:
Look at what happens to girls/women in the 90th percentile between 10 and 30. Because girls develop faster they are highly competitive with boys up until around 15, and then the “great grip divergence” kicks in. Both men and women get stronger between 20 and 30 (to my surprise), but men gain a lot more. At age 30 in standard deviation units the average women is about two standard deviation units below the average man. This would put the average women at the 2.5th percentile of men assuming a normal distribution. The raw table is below the fold at the bottom of this post. The paper is Grip Strength across the Life Course: Normative Data from Twelve British Studies.
The data to the left are from the paper Hand-grip strength of young men, women and highly trained female athletes. It is a German study, and compared three populations: normal men, normal women, and elite national level athletes in Germany in judo and handball. Judo and handball were selected because grip strength are at a premium in these two sports.
To their surprise the average female athlete was at the 25th percentile for males.
Many people will find this post a bit ridiculous. Who doesn’t know that men aren’t stronger than women?
First, there are some academics who believe that increased training will allow women to converge with men in strength, and therefore they propose to end sex segregation in sports. Proponents of this view say thinks like this:
Could that change? Could women start catching up with men again? After all, people used to say women were unable to handle political office. Even the slowest-converging lines eventually do merge; the truth is nobody knows for sure if that’s the case here. The history of women in sports is a history of being gradually allowed access to social privileges which have made them better athletes, and there could yet be undiscovered factors at play that could make the gap smaller.
There’s no comparison between political office and athletic performance. Second, the slowest converging lines do not eventually merge by necessity.
Second sometimes it is good to have numbers. I am not in the habit of getting into fights with women, ten year olds, or senior citizens, so I don’t have a quantitative grasp of how I “stack up.” I don’t beat my children so I don’t have a good sense of how much stronger than them I am, though my parents did beat me on occasion so I have an intuition about how it is on the other end. My grip strength is probably five times greater than my daughter’s. Good to know.