Can Cycling Lower Your Risk Of Knee Arthritis?

Picture by Dennis Thong

I have written previously on what causes osteoarthritis (OA). Definitely not because of overuse nor a mechanical wear and tear process. Especially for those without any previous history of knee truma/ injury, there is very good evidence that OA is actually due to metabolic factors. Well, now a new study (Lo et al, 2024) suggests that cyclists are less likely to develop OA in their knees.

Lo et al (2024) studied 2600 older adults with and without knee OA using knee X-rays, subjective knee pain, and a questionnaire regarding their lifetime history of various physical activities during 4 periods of their lifes: 12 to 18 years old, 19 to 34, 35 to 49 and over 50. 

The study used 3 different outcomes. Persistent knee pain, OA based on X-rays (radiographic OA) and symptomatic OA (having both knee pain and radiographic OA. Note that what is seen on X-ray (OA knees) does not always correspond to pain. This means that some subjects had knee radiographic OA but NO pain.

Almost half the subjects reported some history of cycling and these subjects were less likely to have OA in their knees. How much less? Those with any history of cycling were 17 percent less likely to have knee pain, 9 percent less likely to have radiographic OA and 21 percent less likely to have both. 

Half of those who cycled reported only cycling regularly during one of the 4 age periods, usually the youngest age period from 12 to 18 years old.

Those who cycled during 1,2,3 or 4 of the periods studied reduced their risk of symptomatic OA (i.e. painful knees) by 17, 19, 28 and 43 percent. Meaning lifelong cyclists reduced their risk of symptomatic OA by nearly 50 percent.

The researchers also found that subjects with a history of swimming, strength training and running had lower rates of OA. This is consistent with previous evidence that running DOES NOT ruin your knees despite what every non runner and ex runner you know will insist running does.

You may love watching the beautiful game, but a history of playing the beautiful game (football) even just as a teenager bumped up knee OA risk by a factor of 2. This elevated risk remained even after adjusting for BMI, suggesting that the problem is likely related to acute knee injuries suffered while playing football. 

Picture by Dennis Thong

The researchers concluded that more cycling is associated with less knee pain and favorable to knee health and should be encouraged. 

If you have never cycled previously and would like to start, do note that almost half or the current or former cyclists in the study had radiographic evidence of OA. A quarter of them had symptomatic OA (painful knees). Is cycling better for OA once you do develop OA compared to say running? Is cycling capable of slowing its progression? Currently, we still do not know.

Those of you who have been always been cycling, you definitely have another reason to do so. 

Reference

Lo GH, Richard MJ, Kriska AM et al (2024). Bicyling Over A Lifetime Is Associated With Less Symptomatic Knee Osteoarthritis : Data From The Osteoarthritis Initiative. Med Sci Sp Ex. DOI: 10.1249/ MSS 0.0000000000003449

All pictures by Dennis Thong. Many thanks to Dennis and Eugene Phua for the pictures.

Latest Research On The ITB (Iliotibial Band)

Picture taken with my Canon Ixus 

Mention the ITB (or iliotibial band) and images of pain quickly crop up. IT band syndrome is a painful overuse injury usually at the lateral (or outer) portion of the knee in many runners and cyclists.

Latest research on the IT band from Daniel Lieberman's Harvard lab by his former student Carolyn Eng shows that the IT band may not function as what was formerly believed.

Another view

The ITB runs along the outer part of the thigh, originating from your Tensor Fascia Lata and Gluteus Maximus muscles just above your hip to attach just below the knee. It is made up of fascia, an elastic connective tissue found throughout our body. Fascia is a sheath of connective tissue that wraps our muscle, nerves and blood vessels. It also connects our muscles to bones.

The researchers used human cadavers to investigate how the IT band moves and stretches during walking and running. A computer model was then built to calculate the forces and strains involved and then compared to the equivalent structure in chimpanzees (published in another journal).

Previously, the IT band's primary function was believed to stabilize the hip during walking. Carolyn Eng's research suggested that the IT band actually acts like a spring, storing energy when you swing your leg back and releasing it as the leg swings forward.

This energy storage capacity is highly developed in humans, enabling it to store 15 to 20 times more energy than a comparable structure in chimpanzees.

Lieberman suggested that if we consider evolution and how humans are adapted not just for walking but running as well, then the IT band is looked at at a totally different perspective. The IT band looked like another elastic structure, similar to the Achilles tendon, and this may be important for saving energy during walking and especially running.

The researchers estimate the IT band stores about seven joules of energy during fast running compared to about the standard estimate of about 50 joules in the Achilles tendon.

The researchers hope that with this improved standing of how the IT band works, they can compare how much forces the IT band transmits in runners with and without IT band pain. This will then establish a scientific basis for treating IT band injuries.

References

Eng CM, Arnold AS, Liberman DE et al (2015). The Capacity Of The Human Iliotibal Band To Store Elastic Energy During Running. J Biomech. pii: S0021-9290 (15) 00354-1. DOI:10.1016/j.jbiomech.2015.06.017.

Eng CM, Arnold AS et al (2015). The Human Iliotibila Band Is Specialized For Elastic Energy Storage Compared With The Chimp Fascia Lata. J Exp Biol. 218(15): 2382-2393. DOI: 10.1242/jeb.117952.

Here's Carolyn Eng's (Harvard University) computer simulation of a human leg running from here.

Cycling And Knee Pain

With the OCBC bike race this weekend, both our clinics have been seeing quite a few cyclists this past week and so I thought I'll do a write up on the combination of cycling specific factors that can cause ailments/ grief to your knees.

These factors can often be divided into cycling specific reasons, bike specific and cyclist specific reasons. Cycling specific causes are mainly due to suddenly increasing distances, intensity, hills, using heavier gears and lower cadences while bike specific reasons are likely to occur when radical changes are made to your saddle height, setback and/ or cleat position.

I will elaborate more on the cyclist specific factors that can cause your knee injuries as this often happen due to your own individual make-up and biomechanics, i.e. intrinsic rather than extrinsic reasons.

The first cyclist specific factor that can cause your knee pain is usually due to anatomical differences such as a leg length discrepancies (bearing in mind most of us will have this). Most often though, I've found that most cyclist tend to favor one leg over the other. This is usually the leg with your thigh closest to your seat post when you are pedaling which partly explains why knee pain seldom affects both knees equally.

All of us have had falls, knocks, scrapes and other injuries which may lead to us subtly changing the way we move and so previous injuries (cycling related or not) can also be a contributing factor to causing knee pain. This is especially more so when we decide to ride more than normal at the start of the season or when we have a new bike etc.

The cumulative effect of the two reasons mentioned above can then upset the forces your knees have to deal with while pedaling. Each pedal stroke bends and straightens the knee joint but it should never straighten your knees fully (if it does, your saddle is too high). The push (straightening) phase starts when your knees are bent at about 110 degrees, and the knees start to bend again at about 35 degrees (when you start the pull phase of your pedal stroke). Your muscles and tendons around the knees are the direct shock absorbers for the forces transmitted there. Hence overused or tight muscles which arise from repetition (with you turning the pedals over and over again) can contribute to increased forces to your knees.

The accumulation of excessive loads over time can exceed your body's ability to dissipate forces which can lead to damage if not given a chance to recover, which then leads to injury (hence the need for rest days).

The good news is the vast majority of these cycling specific knee pain improve quickly (with non-operative intervention) with correct identification and treatment of the cause of your pain, something which we at Physio and Sports Solutions are good at.

Please come look for us if you need. And all the best to all of our patients who are taking part in the race.

*Thanks to my patient KM for allowing me to take a picture of his knees.