Choosing your running shoes

There’s a large debate currently over whether running shoes are beneficial or detrimental to the human body. For many years injuries have provoked conversation over footwear and the potential to reduce injuries. Medical professionals have sort to provide shoes for multiple purposes, whilst marketing teams have brought new designs and styles due to consumer demand. This leads to a mass of choices within the shoe market. Discovering which shoe is best for your purpose and whether a shoe is preventative of injury or in fact causal is a difficult question to answer.

Barefoot running has also entered the debate with claims of reduced rates of injuries due to a more “natural” running style (see the barefoot running debate)

Which running shoe is right for me

When choosing a running shoe multiple factors need considering. As a general rule of thumb, lighter shoes reduce running economy making them the choice for races whilst more cushioning is important during larger training loads. My personal recommendation is to gradually reduce the amount of heel drop and stiffness of your shoes whilst keeping a moderated amount of cushioning. Not all people will be able to achieve this minimally shod running gait. People with flat feet, may not be able to modify their foot structure enough to handle and flatter none supportive shoe.

I don’t believe barefoot running is advisable and sustainable on hard surfaces. The foot structure will not evolve enough in one life span to out-perform a running shoe on a hard surface

Heavier people due to higher impact loads will require larger shoes with more cushioning. They may also benefit from a greater degree of heel drop to help distribute loads from the foot structures to further up the leg. Slower runners may find an increased heel drop more economical and sustainable for longer distances. Faster runner and shorter events will benefit from flatter low heel drop shoes, which reduce foot contact times and shoe weight. Heavy pronators with a history of ITB, plantar fasciitis and Achilles injuries are initially recommended supportive shoes and may benefit from orthotics. Whether this is only a short term requirement until the injury declines is not known. Also it is not known to what extent a flat flexible foot can adapt, particularly into adulthood. Flat feet may need medial posting and increased heel drop, but once again try to minimalize this gradually attempting to retrain the foot muscles. Rigid high arch feet may require more cushioning from a neutral shoe and benefit from a lower heel drop.

The arch of the foot develops in early childhood and choosing flat, flexible but cushioned shoes may help develop the arch of the foot

When changing footwear it‘s important to gradually increase your training distances. Muscles adapt quickly but bones and tendons take months to years to completely adapt. Learn which end of the support and heel rise scale you are on and aim for a gradual decline of heel drop and support. If new injuries arise, return to your accustomed level of support. Your foot structure and running style is most likely better suited to this shoe. If attempting barefoot training do so on grassed or padded surfaces. Barefoot running on hard surfaces won’t increase your performance, particularly at high speeds. Reducing your heel drop and wearing a lighter shoe with mild cushioning is a more sustainable alternative 

Footwear changes running technique

The moment footwear comes in contact with your feet you have effectively changed the structure of your foot. Feedback from your neural system will cause you to adjust your technique to perform optimally in what are essentially your new feet.  Imaging running down the road whilst wearing pair of ice stakes. Obviously your “natural” technique is now hampered, but what is important to note is the running technique you adopt in the skate will be the most efficient for your new condition. These changes in technique that occur with differing footwear are of relevance when discussing injury prevention and also peak running performance

Impact of shoe weight on running biomechanics

 Shoe weight has been shown to significantly increase running economy at a suggested rate of 1% per additional 100 grams (Frederick, 1984, Franz et al, 2012, Divert et al, 2008). Using body mass equations this is around 3-5 times the increase in load of placing the same weight on the torso. It terms of running performance a 150 gram shoe (racing flat) in comparison to a 350 gram shoe (largest supportive shoe) will result in a reduction in running time of 4.8 seconds per kilometre or 48 seconds over 10km

Interestingly as shoe weight increases there is a decrease in stride frequency and a subsequent increase in stride length. The extra weight of the shoe increases the effort to lift and swing the legs through on each gait, in response it is more efficient to now reduce the number of steps taken to cover the same distance. This can have effects on impact loading injuries

The impact of heel height on running biomechanics

Increasing the height of the heel of a running shoe has benefits in pronation control. Pronation increases as the ankle is dorsi flexed (foot brought closer to the shin). Raising the heel as seen with the majority of training shoes decreases calf muscle and intrinsic foot muscle activity, this is beneficial in shifting the loads from the foot, Achilles and plantar fascia. There is a decreased ankle range of motion with raised heeled shoes, as a result the hip muscle and extensors contribute to a larger portion of the running gait. Stride length may also increase to better utilize the heel of the shoe. With increased stride length there may be higher rotation forces at the hip on foot strike (Heiderscheit et al, 2011) and muscle activity will most likely be higher in the hamstring and glutes as opposed to the lower leg as seen in barefoot running. The change in gait that is found with the addition of a heel may be helpful in taking strain off the foot muscles, Achilles and plantar fascia, the opposing argument is that these muscle and foot structures are losing their function through disuse. Millar et al, 2014, found after 12 weeks of training in minimal shoes (< 4mm heel drop) there was an increase in the size of the intrinsic foot muscles associated with supporting the arch of the foot. This increased strength is a training adaption due to use

Medial posting, arch support and foot types

Increases in stress fractures and injuries of the lateral structures have been reported in high arch supinated athletes. Whilst injuries to the medial shin, knees and possibly mid foot bones have been noted in pronated (flat) foot types (Yates et al, 2004, Williams et al, 2001) Choosing cushioned shoes will decrease loading forces and increase pronation. Shoes with a low heel drops may promote a lower impact forefoot gait

Increased heel drop shoes with medial posting or orthotics may be beneficial for pes planus (flat) feet.

Medial posting and orthotics have been shown to control pronation of the foot and internal rotation of the femur. Research is debated but professional opinions have suggested this improved control of the lower leg can have a positive benefit on conditions such as patellofemoral pain, ITB pain and medial tibial stress syndrome (see common running injuries). Similar to the above discussion on heel height, medial posting decreases the use of the muscles involved in pronation control. This can lead to a detraining of those muscles. On the other hand if the strength and bone structure fails to improve in less supportive shoes, then medial posting and arch support might actually be the only method allowing these individuals to maintain their training load 

Summary

• Lighter shoes improve running economy and improve performance
• Low heel drop (flat) shoes increase foot and lower leg muscle activity improving arch and foot function
• Pronation injuries such as patellofemoral pain, ITB syndrome, medial tibial stress syndrome and Achilles tendonitis will initially benefit from arch support and an increased heel height. Gradually reducing these supportive elements over time may help to retrain foot muscles
• Heavier athletes will require a larger shoe with increased cushioning
• Foot structure effects injuries pes planus (flat) feet will benefit from more heel drop and support to lower foot stresses
• Pes Cavus (high arch) feet will require more cushioning and benefit from flatter low heel drop shoes
• Flat shoes decrease foot contact times and improve running speeds over short distances
• Slower runners may prefer increased heel drops in shoes to improve heel to toe running efficency

References

Divert, C., et al. "Barefoot-shod running differences: shoe or mass effect?."International journal of sports medicine 29.06 (2008): 512-518

Franz, Jason R., Corbyn M. Wierzbinski, and Rodger Kram. "Metabolic cost of running barefoot versus shod: is lighter better." Med Sci Sports Exerc 44.8 (2012): 1519-25.

Frederick, E. C. "Physiological and ergonomics factors in running shoe design."Applied ergonomics 15.4 (1984): 281-287

Heiderscheit, Bryan C., et al. "Effects of step rate manipulation on joint mechanics during running." Medicine and science in sports and exercise 43.2 (2011): 296.

Miller, Elizabeth E., et al. "The effect of minimal shoes on arch structure and intrinsic foot muscle strength." Journal of Sport and Health Science (2014).

Williams Iii, Dorsey S., Irene S. McClay, and Joseph Hamill. "Arch structure and injury patterns in runners." Clinical biomechanics 16.4 (2001): 341-347.

Yates, Ben, and Shaun White. "The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits." The American journal of sports medicine 32.3 (2004): 772-780