You've probably heard that your twenties are the prime of your body. Experts offer a more nuanced perspective: our full physical potential often comes a little later, around our thirties. And above all, it's not a question of "value" or "merit": every body is unique, and age is just one number among many.
Peak fitness between 26 and 36 years old
A Swedish study conducted by the Karolinska Institutet followed 427 men and women aged 16 to 63 for nearly 50 years, repeatedly measuring their cardiorespiratory capacity, strength, and muscular endurance. The results are surprising: overall physical fitness generally peaks between 26 and 36 years of age, reaching its maximum around 35, in both women and men.
More specifically, cardiorespiratory capacity and muscular endurance peak around age 35–36, while explosive power, such as jump height, plateaus slightly earlier before declining more rapidly. These figures show that the body is not "at its peak" in one's twenties, contrary to popular belief.
After 35 years: a gradual, but adjustable, decline
After the peak, physical decline sets in gradually. According to the study, abilities decrease by 0.3 to 0.6% per year initially, then by 2 to 2.5% per year from around age 50. Between the peak and age 63, the total loss varies from 30 to 48%.
However, these figures are not set in stone. The downward trend varies considerably from one individual to another. Some people maintain a remarkable level well beyond the age of 50, while others experience a more rapid decline. This demonstrates that your lifestyle, habits, and daily choices matter far more than the age indicated in a study.
Moving makes all the difference
Research highlights a key point: physical activity transforms the life course. People who are active from adolescence into adulthood reach a higher peak and subsequently slow the decline in their performance. Even those who start later still gain 5 to 10% more physical capacity compared to sedentary individuals.
Maria Westerståhl, one of the researchers, sums it up: "It's never too late to start moving." Exercise doesn't stop the decline, but it significantly slows it down and postpones the point at which the loss of abilities becomes a daily struggle.
Aging begins earlier than we think
The results confirm what studies on athletes had already shown: significant physical decline begins before the age of 40. Muscle mass, stamina, power: everything decreases gradually, but initially subtly. However, this biological reality should not be interpreted as a verdict on your worth or potential.
The real challenge isn't just knowing at what age you're "at your peak," but understanding how to maximize that peak and prolong the pleasure of feeling fit. Quality sleep, a balanced diet, regular activity, and healthy lifestyles remain key to fully enjoying every stage of life.
Ultimately, while the study establishes an average age for reaching peak physical condition, it should be taken with a grain of salt. Every body is different, every journey is unique. The age indicated by experts in no way defines your worth, your beauty, or your energy. It is simply a scientific statistic about general trends, to be used to better understand your body, not to compare yourself to others.
