Do you think the real decline in form comes with white hair? A Swedish team monitored the physical condition of 427 people for 47 years to find out. Their study, carried out at the Karolinska Institute, measured strength, endurance and cardiorespiratory capacity in these adults born in 1958, aged 16 to 63.
Their verdict is: around 35 years oldour fitness reaches a peak, then a slow but continuous decline sets in, even among athletic people. The authors observed that physical strength and capacity begin to decline by age 35 and that significant difficulty may appear before age 40, especially with a sedentary lifestyle. And good news, those who started or increased sport as adults gained 5 to 10% in capacity.
35 years old, the start of the decline in physical fitness
In this cohort, 427 men and women took regular running, cycling, muscle strength and endurance tests. Capacities peak between ages 26 and 35, with a peak around age 35 for maximum oxygen consumption and muscular endurance. After this milestone, researchers already note an annual drop of 0.3 to 0.6% in performance.
Men and women experience declines in capacity at a similar rate, although absolute levels are higher among men. Over the decades, differences between individuals become more pronounced: some maintain much of their fitness, while others experience rapid decline. “Even elite athletes who continue to exercise throughout their lives lose physical function as they age“, explained the authors.
After 50 years, the slope becomes steeper, with a drop of up to 2 to 2.5% per year. Concretely, what seemed easy at 30, like climbing several floors or carrying heavy shopping, then requires much more effort. The researchers plan to revisit the cohort at age 68 to understand this ceiling around age 35.
Sarcopenia: what changes from age 40
This decline is part of a broader process, the
sarcopeniai.e. the age-related loss of muscle mass and strength. The authors of the study report an observable decline before the age of 40, which can lead to fragility, especially among people who are not very active. Without action, studies estimate that a person can lose up to half of their muscle mass around the age of 80, with more falls and loss of autonomy.
Muscles also serve as a health reserve for the heart, metabolism and brain, with studies linking low muscle mass to a higher risk of dementia. When cardiorespiratory capacity drops, the slightest effort causes shortness of breath. A benchmark used for prevention is the inability to climb four floors without stopping, a sign of a physical condition that is already too limited for one’s age. The body alerts well before the cane becomes necessary.
How to slow the decline after 35
To slow down the curve, researchers point out that a
regular physical activity remains the most effective weapon: at least 150 minutes of cardio per week and two muscle strengthening sessions. Even after 40 or 50 years, every step, every squat counts to maintain margin.
“It’s never too late to start moving. Our study shows that physical activity can slow performance decline, although it cannot stop it completely. Now we will look for the mechanisms that explain why everyone reaches their peak performance level at age 35 and why physical activity can slow down the loss of performance without being able to completely stop it.“, said Maria Westerståhl, reader at the Department of Laboratory Medicine, as quoted by Karolinska Institutet.