Health: Muscle balance

Niggling pains? Odd injuries? Time to check your balance

Better balnce means more power

Muscle imbalance is an issue for cyclists – we spend a lot of time on our bikes with most of our effort going through our legs.


If your muscles are out of balance it can easily result in bad posture as well as joint instability, on and off the bike, and directly relates to force produced through the pedals – poorly balanced muscles are less effective at delivering power. So what are muscular imbalances and what can you do to correct them?

Muscles around a joint work in a symbiotic fashion creating tone, strength and length. The relationship between these three factors is known as muscle balance.  

Muscles can be categorised into two types: mobilisers and stabilisers. Mobiliser muscle groups are located close to the surface and over time tend to tighten and shorten. In contrast stabiliser muscles are located deeper, invariably only cross one joint and tend to become weak and long with time.  

Functionally the stabilisers assist postural holding and work against gravity. The mobilisers assist rapid movement and produce high force.

Whilst initially both groups of muscles work together to stabilise and move, over time the mobilisers can inhibit the action of the stabilisers and begin to move and attempt to stabilise on their own.  

This phenomenon is central to the development of ‘imbalance’ and is the essence of what we want to detect and, if possible, reverse. Muscular imbalances can be classified into two broad areas: bilateral and unilateral.

Bilateral imbalance

This refers to imbalances that occur across limbs, and can be quite common in cycling, as we tend to activate greater forces predominantly in one leg during certain periods. For example, when you stop at a junction or traffic lights, you typically take the same leg out of your pedals, and when starting up apply much higher forces through the same leg to get going.

When sprinting, we tend to develop much more forceful contractions on one side than the other during the initial moments. From a bilateral imbalance perspective, it is believed that an individual with a 10% difference between the quadricep and hamstring strength between the left and right sides is thought to be at a greater risk of muscular tendon injury.

Unilateral imbalance

The second term relates specifically to imbalances that exist on one side of the body only. It is not uncommon for cyclists who are either new to the sport or are returning from some time off to have relatively weak muscles. So if you try to do too much too soon you could increase the chances of developing such imbalances, which may ultimately lead to injury.

For example, imbalances in the quadriceps muscles, in particular the vastus lateralis and vastus medialis components may lead to chondromalacia, which is categorised by patella (kneecap) instability and misalignment.  

The vastus lateralis (muscle on the outside of the thigh) tends to be more powerful than the vastus medialis (muscle on the inside of the thigh), thus increasing the tendency for the patella to track or dislocate laterally. This can lead to undue pressure on the lateral side. This uneven and excessive pressure may lead to cartilage “softening” and breakdown, causing pain and discomfort and leading to time off the bike with the knee strapped.

Considering the affects of muscular imbalance from both the bilateral and unilateral perspectives, any such abnormalities in muscle tone, strength and length are going to play a big part in the development of most musculoskeletal pain and dysfunction.

The correct identification of muscle imbalances and the action taken to correct them will therefore help both with injury prevention and with your performance. It is important to be aware of any unnecessary muscular tension when cycling, as tension in the upper body, in areas such as hands or shoulders to lower body muscle groups may be early signs of muscle imbalances.  

Evidence has highlighted that even Elite level cyclists can be as much as 50% stronger on their dominant side, with the imbalance in strength often mirrored by technique.

Good technique = balanced muscles     

Ensure that you spend time developing your technique on the bike and not to over look this important element. One practical example is to try working each leg independently while on the turbo. Use easier gears to develop coordination and leg speed, and bigger gears to develop more symmetrical strength.  You should also get into the habit of regularly inspecting your pedal/shoe interface, as unnecessary wear and tear may be early indirect signs of imbalances.


Anyone who spends lots of time on their bike needs to be aware of muscle imbalance and how to prevent it. If you’re a competitive cyclist, detection of these abnormalities and correction before injury has occurred should be part of your training strategy, thereby ensuring that your muscles are working effectively and in a balanced manner.