- Range of motion is different whether you are young or old.
- In young people, flexibility comes from muscles which can contract and become rigid, which helps to maintain a position.
- In older people, because of muscle wasting, it is the nerves that make the joints flexible.
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, the precautions must be adapted according to age. For example, an older person is more likely to fall and injure themselves than a young person because their joints have become less flexible over time. Researchers at the Technological Institute in Shibaura (Japan) have been interested in the question of flexibility with age. The results were published in the new edition of the monthly Medicine & Science in Sports & Exercice.
Range of motion, the sinews of war
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 capacities. 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 characteristic that influences 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 range of motion is not as strong in older people.
To find out, the researchers asked 40 participants (twenty young people in their prime and twenty elderly around 70) to lie down, then turn their ankles until they were feel pain. This angle of rotation, in which participants could move around without feeling pain, corresponded to their maximum range of motion. Next, the team determined the stiffness of the tissues using a variable called “shear wave velocity,” measured by ultrasound. These measurements were taken for several calf muscles, the sciatic nerve (main nerve in the leg) and 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 amplitude and muscle stiffness in young people but not in older people. Second, the maximum amplitude would correlate with the stiffness of nerves and fasciae in young and old. Finally, the two age groups could have different levels of tissue stiffness.
“There haven’t been a lot of studies that have looked at the link between stiffness in non-muscle tissue and peak amplitude, and if there’s an age difference here, so our goal was to provide answers. clearer to these questions”, Explains Kosuke Hirata, researcher at the Technological Institute of Shibaura.
The results of their experiments showed that as muscle stiffness decreased, peak amplitude increased in young participants. However, this correlation was not noted in older participants. Maximum ankle amplitude also increased with decreasing nerve stiffness, but only in older participants. Fascial stiffness did not correlate with peak amplitude in any of the age groups. Overall, non-muscle tissue, especially nerves, appears to contribute more to joint flexibility as people age.