Research review: staying young and injury free in the long run?

Are lifelong older runners at increased risk of injury due to chronic loading of tendons and ligaments? Peak Performance looks some key evidence

The health benefits of regular exercise are well documented. Not only does regular vigorous exercise reduce the risk of cardiovascular disease and other metabolic conditions such as diabetes, there’s also accumulating evidence that (along with reduced body fat) regular exercise into older age can directly help reduce the incidence of a number of cancers such as bowel cancer and other degenerative diseases(1).

The pros and cons of running

One of the most effective forms of exercise for generating these kinds of health benefits is running. In particular, running is known to produce improvements in body composition and favorable reductions in body fat levels, thereby reducing the risk of a number of degenerative disease, even in beginners(2). However, one drawback to running that is often cited is that the impact forces associated with running may cause cumulative damage to connective tissue – in particular tendons and ligament – and that this in turn could increase injury risk progressively as the years tick by. But is this actually true?

To answer this question, we can consider a landmark piece of research carried out by Danish scientists at the Institute of Sports Medicine and Department of Orthopedic Surgery, University of Copenhagen(3). The researchers examined two groups of healthy elderly men and two groups of younger men:

  • Fifteen master athletes (average age 64 years) who had been engaged in life-long endurance running.
  • Twelve older untrained (66 years) who has been largely sedentary.
  • Ten young athletes (average age 26) who were matched for running distance with the older runners.
  • Twelve 12 young untrained men (average age 24 years).

What the researchers looked for was evidence of damage to connective tissues such as tendons in all the groups. To do this, they measured the connective tissue accumulation of molecules known as ‘advanced glycation end-products (AGEs)’, which are associated with aging and lifestyle-related diseases. In particular, the AGE cross-links (pentosidine) of the patellar tendon (kneecap) were measured biochemically, along with the mechanical properties and microstructure of the patellar tendon using an advanced technique known as ‘fluoroscopy’.

What they found

The key finding was that the life-long regular endurance runners (master athletes) had a 21 % lower AGE cross-link density compared to the older untrained men. Furthermore, both master athletes and young athletes displayed significantly thicker patellar tendons, indicating a stronger and more resilient structure (see figure 1). The researchers concluded that their data suggested that life-long regular endurance running not only doesn’t harm connective tissue, but can partly counteract the aging process in connective tissue by reducing age-related accumulation of AGEs. They also commented that the protective effects of lifelong running not only benefited skin tendon health but also other long-lived protein tissues in the body such as the skin. Finally, the researchers proposed that since years of endurance running had produced tendon tissue hypertrophy (thickening) in the older runners, the physical loading per unit of cross-sectional area was reduced, which serves to lower stress on the tendon, thereby reducing the risk of injury rather than increasing it.


Figure 1: Patella tendon cross-sectional area

Average patellar tendon cross-sectional area (CSA) normalized to body weight. A very significant effect of age (p < 0.0001) and training (p < 0.0001) was observed on weight-normalized tendon CSA. There was a significant interaction between age and training – namely, the **master athletes had a greater tendon CSA than any of the other groups.


In summary

Research has already identified that lifelong running does not increase the risk of joint osteoarthritis(4) (see this article for more info). And what this research shows is that not only does a long history of running not damage tendon health and increase injury risk, it actually improves tendon health, thereby reducing injury risk. The message then is ‘keep running to stay young’!

References

  1. Nat Commun. 2020 Jan 30;11(1):597. doi: 10.1038/s41467-020-14389-8
  2. Res Q Exerc Sport. 2020 Sep 8;1-9. doi: 10.1080/02701367.2020.1799916. Online ahead of print
  3. Age (Dordr). 2014;36(4):9665.
  4. J Bone Joint Surg Am. 2018 Jan 17;100(2):131-137

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