Staying flexible as you age is mostly a matter of nerves

Flexibility is not innate, it can be worked on and preserved over time. The flexibility of a 20 year old is very different from that of a 50 year old. Of course, precautions should be adapted according to age. For example, an older person is more likely to fall and injure themselves than a younger person because their joints have become less flexible over time. Researchers from the Shibaura Institute of Technology (Japan) have been interested in the question of flexibility with age. The results were published in the new edition of the monthly Medicine and science in sport and exercise.

Range of motion, the war tendons

To minimize the risk of accidents and improve the quality of life of the elderly, it is important to develop measures that improve their physical abilities. To do this, it is essential to better understand the factors that affect joint flexibility or range of motion.

Research suggests that in young people, skeletal muscle stiffness is the main feature that affects range of motion. However, muscle size naturally decreases and atrophies with age, and older people tend to have less stiff muscles than younger people. This suggests that the link between muscle stiffness and freedom of movement is not as strong in older people.

To find out, the researchers asked 40 participants (twenty young people in their prime and twenty seniors around 70) to lie down, then twist their ankles until they felt pain. This angle of rotation, in which the participants could move without pain, corresponded to their maximum freedom of movement. Next, the team determined the tissue stiffness using a variable called ‘shear wave velocity’, measured by ultrasound. These measurements were made for several calf muscles, for the sciatic nerve (main nerve of the leg) and for the deep fascia (connective tissue).

The nerves take over

Armed with these measurements, the researchers made three hypotheses. The first is that there is a correlation between maximum ankle width and muscle stiffness in the young but not in the elderly. Second, the maximum amplitude would be related to the stiffness of the nerves and fascia in the young and old. Finally, the two age groups may have different levels of tissue stiffness.

“There haven’t been many studies that have looked at the link between stiffness in non-muscle tissue and peak width, and if there’s an age difference here, then our goal was to provide answers. clearer to these questions“Explains Kosuke Hirata, a researcher at the Shibaura Technological Institute.

The results of their experiments showed that when muscle stiffness decreased, peak amplitude increased in the young participants. However, this correlation was not noted in the older participants. Maximum ankle width also increased with decreasing nerve stiffness, but only in older participants. Fascial stiffness was not related to peak width in any of the age groups. Overall, non-muscle tissue, particularly nerves, appears to contribute more to joint flexibility as we age.