Cycling - Importance of bike set-up
For any competitive cyclist, to train on the road is to accept the risk of serious injury, because of the twin hazards of vehicle traffic and speed. A multitude of orthopaedic injuries occurs with high-speed accidents, but of most concern are head injuries. Because of fatal injuries during competitive cycling, the compulsory use of helmets has been in place for a number of years at the Tour de France, except for the finishing climb in the mountain stages. In Australia, all cyclists (from everyday users to pro competitors) are required to wear helmets or face hefty fines. Throughout Europe, by contrast, there is no such compulsion.
Several studies highlight the neck and back as the main sources of overuse injuries. After a six to eight day cycling tour for recreational cyclists, Wilber et al reported that 54.9% of females and 44.2% of males presented with neck pain for medical treatment, and 30% of both males and females with back pain. Patterson et al. (2003) analysed ulnar and median nerve palsy - often referred to as 'cyclist's palsy' - after a 600 km bicycle ride. Of the 25 riders given physical and questionnaire assessments, 23 had either motor or sensory symptoms. Most symptoms were reported in the hands in the ulnar nerve distribution.
Wilber et al (1995) found 85% of cyclists suffering with one or more overuse injuries: 48.8% had neck problems, 41.7% had knee trouble, 36.1% groin and buttocks, 31.1% hands and 30.3% backs. The study also found that female cyclists are approximately 1.5 times more likely than males to develop neck symptoms. Although neck symptoms are the most common, in my experience knee injuries are of more concern, as they pose a greater long-term risk.
A single pedal cycle involves a power phase from 12 o'clock to 6 o'clock and a recovery phase from 6 o'clock to 12 o'clock. The power phase delivers most of the force that generates forward momentum. This force is produced via the extensors of the lower limb chain: quadriceps, glut max, hamstrings (working at the hip) and calves (working at the ankle). The recovery phase also contributes to overall power delivered in one cycle by the upward pull of the attached shoes via the flexors: hip flexors, hamstrings (working at the knee) and calves (working at the knee).
At 12 o'clock, the knee is flexed to no degrees and then extends 75 degrees through the power phase to 35 degrees flexion at the beginning of the recovery phase. It is important to note that during the power phase the knee will drift medially because of the normal valgus orientation of the femoral condyles (more pronounced in females).
The foot pronates during the power phase, imparting an internally rotating force to the knee, much the same as during the stance phase of running, thereby increasing the stress to the inner side of the knee. The opposite happens during the recovery phase in preparation for another power phase. At the bottom of the power phase, the foot should be parallel to the ground. The lumbar and thoracic spine has to tolerate prolonged flexion and the cervical spine prolonged extension.
Assessment of chronic injury
When a cyclist presents with an overuse injury, the clinician needs to gain an understanding of the following areas to determine the underlying cause:
It is imperative that the athlete's bike is correctly adjusted to suit their specific anatomical alignment, in order to achieve bike-body harmony. Static measurements are useful:
For each injury, the therapist should be aware of the relevant flexibility and muscle balances in order to establish technique faults contributing to injury (for instance, the cyclist may be medially deviating with the left knee or the pelvis may be dropping to the right when the right foot reaches 6 o'clock).
Correct bike set-up is crucial both to maximise performance and to avoid injuries. But very few recreational cyclists are aware of this. If you venture on to the roads on a Sunday morning, you will see droves of cyclists with their seats set too high or their knees grossly deviating left and right. The following table sets out the key positions that the clinician should ensure their client is achieving in the set-up of their bike. Bike set-up can be assisted greatly by two small pieces of equipment: full shoe-length leg raises compensate for leg-length discrepancies, and forefoot varus wedges placed between the cleat and shoe correct knee alignment by allowing the foot to operate in its normal position. Specific cycling orthotics is commonly used.
* The cleat is a plastic piece screwed into the bottom of the shoe to enable the rider to clip into the pedal.
The cyclist also needs to be made aware that they should adjust their bike set-up to suit variables such as the length of race or competitive goal in order to achieve the best balance of efficiency and comfort. In endurance races, the rider will usually opt for a less aerodynamic position to improve comfort, whereas for a short time trial, the tightest possible aerodynamic position and lowest trunk position will deliver maximum speed advantage.
Chronic injury risks
When pedaling, the largest force produced acts through the knee up to 5,000 times an hour, so it is no wonder that the slightest incorrect distribution in load can end up in a serious knee injury. The following table summarises the main injury risks.
Ongoing soft tissue massage, trigger point work and stretching for iliopsoas, TFL, vastus lateralis, ITB and gluteus muscles are all very important, as is maintaining patellofemoral joint mobility. Activation and strengthening of VMO and glut max should be included where necessary.
Neck and back
Neck pain usually relates to the prolonged time that cyclists spend in an extended position. Constant compression of any joint over a long period can lead to the transmission of noxious stimuli; muscle fatigue and trigger points will lead to further joint compression and chronic muscle pain. Any prolonged position will also result in cumulative tensile stress on joint capsules and ligaments, which can bring both pain and long-term structural changes to joint arthrokinematics.
Cervical extension with shoulders in a depressed position increases neural tension, which can be exacerbated by handlebars set too low or the cyclist failing to keep their elbows slightly bent. Excessive or prolonged traction to the nerves can result in ulnar or median neuropathy. This will present as pain, numbness or tingling in the nerve distribution.
To prevent the build-up of tension, the cyclist must learn to do regular cervical flexion movements, lateral flexion and shoulder shrugs on the bike, as well as sitting upright from time to time. Treatment should focus on ensuring adequate thoracic spine mobility, first rib mobility and flexibility in scalene, levator scapulae, rhomboids and upper trapezius muscles. In recalcitrant cases, surgery may be needed to widen the nerve space.
Lower back injuries are very similar in principle to neck pain in cycling, except that the aggravating position is prolonged flexion. Muscle fatigue, chronic tension to posterior vertebral ligaments and prolonged compression to intervertebral discs can all be responsible for ongoing backache. Clinicians need to evaluate gluts, psoas and lumbar extensors for tone and flexibility. It is imperative that cyclists have an adequate range of lumbar spine and hip flexion.
The cyclist's pelvic position during riding is also significant. Sitting in a posteriorly tilted position increases lumbar flexion, so many clinicians look to achieve a more anterior position through the pelvis. This should be addressed when assessing bike set-up and cycling technique.
As cyclists build up their training volume, they often suffer from aches in the cervical, thoracic or lumbar spine, because of the lengthy periods for which they maintain their flexed trunk position. This is normally a matter of building up their tolerance, during which time the therapist should ensure that any joint stiffness or muscle tightness is attended to. For any cyclists intending to build up to a high weekly mileage, the training should be gradual and structured.
As with all postural problems, whether on a bike or not, core stability function is crucial. Regular exercises focusing on muscle endurance should be an integral part of treatment and prevention. Postural exercises for scapular retractors, and especially lower trapezius activation, are essential to minimise neck problems. The lumbopelvic stability muscles not only have to tolerate prolonged flexion but also to continually stabilise the lumbar spine and pelvis to provide a stable platform for the major force-producing muscles.
Core stability exercises for the lumbopelvic area are therefore crucial in the treatment and prevention of lumbar spine pain, especially for any cyclists increasing training volume.
Good hip flexibility also matters greatly, to relieve pressure on the knee and lumbar spine. The hip during cycling always remains in a relatively flexed position, so chronic tightness through TFL/ITB, iliop-soas and adductors is very common. This can also lead to hip and groin problems such as greater trochanter bursitis or hip tendinopathies. All cyclists should perform regular stretches and do trigger point work on these areas. Gluteal and hamstring range also needs to be maintained to be able to sit comfortably in lumbar flexion and to avoid falling too far into posterior tilt. Although a relatively high incidence of hip and groin pain is recorded, my own experience is that, as with many sports, much of this is related to the lumbar spine and pelvis.
Cyclists are also at risk of urogenital problems, such as erectile dysfunction and infertility, mainly affecting those who put in large training volumes. Pudendal neuropathy is the most common presentation, caused by compression of the pudendal nerve against the pubic bone. Statistics range from 50% to 91% of cyclists reporting symptoms (Leibovitch and Mor 2005). A change of saddle to one with an increased width or padding, altering the tilt of saddle and using increased padding in the rider's cycling shorts may all help to relieve the pressure.
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