Anyone experiencing the ageing process first hand can relate to the loss of muscle strength that we experience in later life, and Gaspar Epro, from the German Sport University Cologne, explains that the tendons that connect muscle to bone also become softer and more elastic as we age. ‘This deterioration has been linked to several problems such as tendon injuries, reduced mobility and poor balance while walking’, he says. But are the effects of age inevitable or can anything be done to stave them off? Knowing that calf press exercises – where individuals flex their feet to press on, and raise, a weighted board – strengthen and stiffen the Achilles tendons of younger athletes, Epro and Kiros Karamanidis wondered whether similar exercises might also benefit the Achilles tendons of older people.
With volunteers ranging from 58 to 73 years of age who were already participating in a study of knee osteoarthritis, the team had a willing group of 21 participants that was keen to try Epro's custom-designed exercise machine to find out whether calf press exercises could build up and improve the stiffness of their Achilles tendons. After MRI scanning each volunteer's lower leg with Jonas Doerner and Julian Luetkens – to build a picture of the initial condition of their Achilles tendons – Epro and Karamanidis provided the volunteers with three exercise sessions a week for a period of 14 weeks. However, Karamanidis and Gert-Peter Brüggemann were also keen to find out whether long-term training was also beneficial, so when nine of the original participants dropped out, Epro and his colleague Andreas Mierau continued offering two training sessions a week for another year and 3 months to the remaining volunteers.
Having rescanned the volunteers’ lower limbs at the end of the 14 week training session, the team was impressed to see significant improvements in the condition of their Achilles tendons: in addition to increasing the thickness (cross-sectional area) of the tendon by 6%, the tendon was 23% stiffer and 20% stronger. The exercise had also developed the calf muscle, increasing its strength by 22%. ‘Most of the volunteers noticed that it was easier to walk and to keep their balance, so everyday life had already gotten slightly better during the first 2 months. And a few told me they felt way stronger, which meant that they needed to order new winter boots because their calves did not fit into the old ones anymore’, says Epro with a smile.
However, when the team followed up the volunteers at the end of the 1.5 year study, the condition of the tendon had not improved any more. Epro says that he was surprised, but the lack of progress seemed to coincide with a plateau in the calf muscle strength, which may have limited the tendon's ability to improve.
Admitting that he was impressed that the cross-sectional area of tendon had increased to such an extent during initial training, Epro says, ‘We were expecting that to happen rather later in the training’. And he is excited that it is possible for older people to improve their quality of life by strengthening the Achilles tendon. ‘Some of the subjects were surprised and happy that they could play longer with their grandkids and stay at the Christmas market longer before getting tired’, he says.
- © 2017. Published by The Company of Biologists Ltd