Cycling is supposedly a low impact, aerobic sport.
However generally, as the exclusive content of a person's training, it developes specific weaknesses and susceptibilities to injury- acute or chronic.
I developed rather typical symptoms and problems. Firstly I had an outer quadracept-dominance issue. I don't know why this developed because I used LOOK pedals during my largest phase of training ( 8-14 hours weekly). Perhaps it was an existing predisposition or my lack of sportiness before taking up cycling! This lead to the typical floating knee cap with water on the knee, and associated discomfort. Worse, the rigours of mountain biking, with high cadence , impact and an accident or two lead to aggrevation in this area.
However, I took to the gymn and balanced my knees out. Upon coming back to cycling hard this autumn, I noticed a marked definition on my inner quads and also a tightening of the knee cap- the reverse of the previous situation.
A more serious problematic is the legnthening and weakening of the muscles of the lower back and lumbar region. The ham strings and the glut' muscels seem to work at odd with each other, excarebating the tendency to develop instability in the lower lumbar and dorsal-pevlic/spine interface. The ham strings tighten with use and expanding musculature thus pulling down on the glut' muscles which are conversely under employed and in a relaxed state under much of cylce movemnet.
The mid - upper -lumbar region of the spine is supported in a near weightless state by the majority of wieght being borne either end and this part of the spine in neither
2) verticle movement stress
3) tortional challenge
These problems are well documented and to give a lay mans appraisal, a combination of the above leads to the following situation:
The lower back becomes weakened, with the discs and nerve/fibrous areas becoming prone to small prolapse and unusual pressure leading to pain and spasm. The whole spine is weakened as a result of excløusivbe and prolonged cycle training and is prone to various injury, spasm and irregular movements. The normal rotation of the pelvis in relation to the spine and thigh bones is compromised and developes discomfort and susceptibility to injury.
How to remedy this?
Well - three main ways- Pilates, Pilates, Pilates. OBS!! Avoiding the more stressful bending from standing until a very secure musculature has developed around the 'body core'. There have been various other techniques- socks on hands, and the use of ropes with foot and hand loops to introduce random challenge and develope supportive core muscles, but none offer the comprehensive approach of pilates.
Stretching the ham strings often - learning safe floor techniques and bent-knee squat style for outdoors. Stretching, general key muscle groups and the body core, after a light 10 mins warm up and gentle, slow stretching after all runs.
Also while riding, varying the technque conscioulsy - coming out of the saddle more often, recruting the spine in varied movements - dropping shoulders or pelvis on each side under 'hiking' up out the saddle. Cycling free handed. Rotating shoulders. Rotating pelvis forward and taking short, light sprints or climbs with a straighter spine.
Varying exercise form is also imporant- if you are a commuter cyclist along good cuity cyucle ways then it is good to maybe develop roller blading with X-country ski poles as an alternative for some days, or actually using the road skis. Consider jogging home or to a public transport point some days. If you have a reasonable hill of more than 100m between you and work, taking a pack, starting and 10kg and progressing up to 30 kg with a varied gate and sensible use of the spine is good. This builds bone mass as well as body core muscle.
In my own experience I found swimming did not do a lot of good for my lower back, pelvic rotation or knee problem. But in general it relaxed my body and built a stronger mid to upper back and built shoulders and arm fitness for my sailing exploits..that and the comfort of knowing I could maybe swim somewhere useful after a sinking or M.O.B.!
Weight training, pleiotropics, and general gymn iron and aerobic maskin work outs are good but often they isloate the muscle group and do not employ the core muscles. Learning to use free weights, starting with the bare '5kg' bar under strict proffessional supervision is a good way to build an all round stronger body and will contribute to you cycling prowess as much as the fixed machines for knee curls etc.
The other problem with gymn work is duration and committment/motivation- it can be dull, humid and individualistic for cyclists used to team riding out in the countryside.
Cycling is often not an easy bed fellow with 'court' sports ..the use of muscles is often at odds between the more stamina and high revlution explosiveness focused on the leg muscles rotating compared to the quick, darty explosiveness of tennis, volley ball or five a side. But for the less serious cyclist, perhaps a commuter as above, the inclusion of two court sports days is a good means of varying body movement. Pure cyclists are prone to injury when combining these, and some should seemignly avoid all sprint-running with such sharp turns and impact as these types of court sports entail.
Finally a quite sensible alternative second sport, and form of mid winter training, is martial arts like jujistu, shorinjii kempo, aikido and judo. Karate forms and dojos often focus on very stiff poise and explosive power strikes which do not IMHO mix well with cycling. THe others mentioned generally involve very good warm up exercises, stretching, meditation, warm downs as well as the actual art's movements and eventual sparring. Training usually takes place bare foot on soft or sprung floors with use of mats for technique development. This reduces the impact on the body in comparison to court sports. ALso the duration is often in excess of two hours, building fitness and stamina as well as range of movements and whole body stability.