It is important to wear appropriate footwear, regardless if it is during sport, work or in casual circumstances. Doing so helps reduce the chance of aches / pains whilst also complementing treatment, posture, performance and reducing the chance of future injury...
• Not only can footwear damage the structure of your feet and thus affect body alignment (i.e. high heels), it can also inhibit natural running form thus increasing certain adverse forces (i.e. eccentric loading forces) through the lower limb (i.e. running shoes with thick soles - high heel pitch in relation to forefoot height/thickness).
• Footwear should not adversely alter or inhibit the natural movement of your feet. The feet should be allowed to function as naturally as possible within shoes. Inappropriate footwear for the individual can lead to injuries i.e. running related overuse type injuries such as Plantar Fasciitis and Shin Splints.
• In regard to running, the issue of footwear and their impact on injuries and performance has become a controversial one. Many believe that the structure and designs of today's running shoes are in place to help reduce injuries. Whilst this isn't an easy claim to assess (i.e. due to the potential multifactorial nature of running injuries); one just has to ask why has there been no real reduction of the occurrence of running injuries since the American running boom of the 1970's (i.e. some types of injuries have dropped, whilst other types have increased). In fact, it is estimated that 40 - 50% of runners still get injured every year. Yet over the decades there has been a myriad of shoe characteristics (gimmicks) promoted to aid in better support / control & cushioning.
I am one who believes that the variety of supportive / controlling ('corrective') and cushioning trends of modern running shoes have a lot to answer for in relation to contributing to poor / inefficient technique, adverse foot strike patterns with associated adverse forces contributing to tissue / bone stress and subsequent injuries. Many in my profession (as well as shoe companies) would not agree with this view... but I have had to go where the evidence leads, how the foot was designed to function and the evaluation of my own experience over the many years running thousands of kilometres in various shoe types.
I feel the majority of the running shoes on the shelves today have a heel pitch (heel height greater than forefoot height) which is too high and a midsole that is generally too thick and stiff. These factors alone can contribute to poor technique / form as well as induce adverse forces which not only could contribute to injury but also to earlier onset muscle fatigue (thus contribute to greater delayed onset muscle soreness [DOMS]), subsequently hindering performance and recovery potential.
Some studies have revealed that the variety of motion control elements which are primarily designed to address pronation within running shoes do not even effectively (if at all) alter the degree of foot pronation. Thus are really of little (to no) use and just add unnecessary bulk / thickness, stiffness and weight to the shoe.
As far as the variety of cushioning elements of shoes; these are added to address those adverse impact forces which contribute to adverse stress directed to the lower limb. Some studies are now questioning whether the cushioning elements within midsoles are doing their job effectively. Putting aside the nature of impact forces (i.e. peak loading degrees and times), there appears to be little to no protective benefit between running on softer surfaces as opposed to running on harder surfaces. This is the result of the mind and body's reaction to addressing the forces via a mechanism known as pre-activation and muscle tuning.
We underestimate the human body! It's an amazing thing, and we hardly ever give it the credit it deserves. The human body has the ability to adapt to the surface the foot is about to strike via visual and proprioceptive (sensory) feedback. The body adapts to both shoe and ground surface hardness / stiffness and thus varying impact forces via adjusting peak loading via three mechanisms - adjusting joint stiffness, the way the foot strikes and a concept called muscle tuning. Surface hardness and impact forces are a signal or a source of feedback. When running, the body takes in all the sensory info, plus prior experiences and make the appropriate adjustments to protect itself and land optimally. The body then uses this information and adjusts accordingly to minimize soft tissue vibration and / or bone vibration. However, when we wear a bulky shoe (with thick midsole), proprioception (sensory feedback) is diminished thus the body's ability to make the appropriate adjustments is also diminished. Hence, surface hardness and impact forces is not the real problem; it is the diminished / altered signal via poor proprioception which then alters the neurophysical control of joint and muscle stiffness thus affecting our preparation for impact. This subsequently subjects our lower limb to adverse torsional (twisting) and loading forces (i.e. eccentric loading forces)... which can potentially lead to soft tissue (i.e. muscle or tendon) or bone (i.e. stress fracture) type injuries. Thus the ideal objective behind running shoes is to allow the foot to function naturally as it was designed to do and not adversely inhibit the protective proprioceptive feedback gained from its environment.
Appropriate footwear will vary from individual to individual. The most obvious factors are based on sex, foot shape and the activity type the shoes are intended for (i.e. work or casual). In regard to sport, footwear is even more activity specific based on the surface and the level / quantity the footwear is used for (i.e. Track and Field, Cross Country or Road Running). Other important factors also involve what type of foot / lower limb function you have... however, this is potentially far more complicated to describe via this format in a general sense, thus a visual assessment is beneficial. However, due to what has been discussed as far as proprioceptive feedback etc... I feel footwear should not be as diverse in structure and cushioning (i.e. in bulk and midsole thickness) as is currently the case, due to the need to allow the foot to function as natural as possible with appropriate proprioceptive feedback. For more information regarding this topic, see the Barefoot Running section on this site.
♦ Footwear & Running Efficiency (economy):
Researcher and acclaimed coach Dr Jack Daniels has been involved with research involving the difference between running in shoes and running barefoot in regard to performance. These tests were carried out on a treadmill. Barefoot running revealed to be more costly (i.e. cost more energy to run at the same speed) compared to running with shoes on the harder surface. It is believed that this was because the treadmill was hard (similar to that of the road) and thus you have to use the leg muscles more to absorb the landing shock.
Tests have also revealed that each 100 grams of weight added to running shoes increases the cost of running (cost more energy to run at the same speed) by about 1 percent. “Increasing the weight of a shoe increases oxygen consumption at moderate running speeds by approximately 1% for each 100 grams of added weight”; 100 grams = 3.5 oz. (Morgan DW, Martin PE, Krahenbuhl GS. Factors Affecting Running Economy. Sports Medicine 1989; 7:310-330). This equates to about 1 minute in a marathon and about 12-15 seconds over 10km. Dr Daniels has also carried out tests which have also measured energy expenditure wearing shoes of different weight (again tests performed on a treadmill). As the shoe was lighter, the cost was less, but when the shoe was very light, the cost started going up again because very light shoes have limited shock-absorbing characteristics, so the muscles start having to work more (like with barefoot running on the treadmill).
♦ For further reading on this topic, the following Runner's World article... Barefoot Vs. Running Shoes: Which Is (Surprisingly) More Efficient? discusses recent research on the area... Metabolic Cost Of Running Barefoot Vs. Shod: Is Lighter Better?
♦ The following running shoes are past training shoes of mine. These are from Nike and are a step in the right direction in relation to their design and structure. They are from the Nike Free range (5.0, 4.0 and 3.0) and they have a smaller heel to forefoot pitch, less bulk and more flexibility than the usual conventional running shoe. The basic concept behind the numbering (i.e. 5.0, 4.0 and 3.0) is that the 3.0 has a smaller heel to forefoot pitch and less bulk than the 5.0, thus the 3.0 will provide a closer 'barefoot' feel than the 5.0.
There will likely be more running shoe companies in the future that will follow Nike's lead in designing running shoes that fit the minimalist / 'barefoot' shoe structure. New Balance will be bringing out a shoe in March 2011 called the NB Minimus which may look something like the following...
However, if you want a closer 'barefoot' running feel then there is the Vibram FiveFinger range. These are basically gloves for your feet developed by a company known for providing rubber soles for a variety of footwear companies. The following is a pair I train in to get the barefoot running feel whilst working on drills / technique; albeit modified somewhat via providing a bit more padding (i.e. poron) within the 'shoe'...
NOTE: THE ABOVE MINIMALIST TYPE RUNNING SHOES ARE NOT FOR EVERYBODY DUE TO SOME PEOPLE HAVING POOR LOWER LIMB STRUCTURAL ALIGNMENT THUS COMPROMISED BIOMECHANICS. THE ABOVE MINIMALIST TYPE RUNNING SHOES MUST BE USED WITH CAUTION AND GRADUAL ADAPTATION SHOULD BE ADHERED TO UNLESS AN OVERUSE TYPE INJURY MAY RESULT (I.E. ACHILLES TENDINOSIS, PLANTAR FASCIITIS, STRESS FRACTURE ETC...). THE LENGTH OF ADAPTATION PROCESS WILL VARY FROM PERSON TO PERSON PRIMARILY BASED AROUND THEIR OWN BIOMECHANICAL EFFICIENCY AND LOWER LIMB MUSCLE / TENDON STRENGTH / INTEGRITY.