Achilles Tendon Length And Running Performance

My patient's L Achilles

Two years ago, after my marathon running patient tore his left Achilles tendon (AT) and had it repaired. About six weeks after the surgery, his surgical site got infected. The surgeon had to remove the repaired tendon. After the infection was cleared, the surgeon grafted the lateral gastrocnemius (calf) muscle to repair the tendon. 

Needless to say, he couldn't really run let alone think of finishing another marathon. After trying traditional Chinese medicine (TCM) and seeing another physiotherapist for over two years with not much improvement, a fellow runner I've treated before suggested he come and see me.

For runners, the hips, knee and ankle joints generate large amounts of forces during running. The ankle joint (via the Achilles tendon ) contributes remarkably to supply the power required while running.  

R calcaneus bone, where the Achilles inserts

The AT plays an important role in storing and returning elastic potential energy during the stance (foot flat on the ground) phase in walking and running. 

L Achilles inserting on calcaneus

I was wondering how else to help my patient when I came across a research paper investigating AT length and running performance on male Japanese 5000 meter runners (between 20-23 years of age). Their personal best times range from 13:54 minutes to just under 16 mins.

Their running economy was tested by calculating energy costs with three 4 minute runs at running speeds of 14, 16 and 18 km/h on a treadmill with a 4 minute active rest at 6 km/h.

Ready for the results? The researchers found that absolute length of the medial (inner) gastrocnemius (or calf), but not lateral gastrocnemius and soleus muscle correlated with a faster 5000 meter race time and lower energy cost during the submaximal treadmill tests at all 3 speeds tested.

This is after normalizing medial gastrocnemius muscle length with the subject's leg length. That is, the longer the medial gastrocnemius muscle, the better the running performance in endurance runners.

For the medically inclined, note that each AT length was calculated as the distance from the calcaneal tuberosity to the muscle tendon junction of the soleus, medial and lateral gastrocnemius respectively.

Possible reasons to achieving superior running performance may be that the longer medial gastrocnemius and AT store and return more elastic energy (and potentially reduces energy cost) from the ground reaction force compared to a shorter AT.

Have to treat both R and L leg

Reading that paper definitely gave me more clues to treat my patient (and other patients with Achilles tendon and plantar fascia problems). I am happy to say that my patient has since progressed to running up to 12 km.

He is now definitely looking forward to running his next marathon.


Reference

Ueno H, Suga T et al (2017). Relationship Between Achilles Tendon Length And Running Performance In Well-trained Male Endurance Runners. Scand J Med Sci in Sp. 28(2): 446-451. DOI: 10.1111/sms.12940.