BAREFOOT VS RUNNING SHOES: BIOMECHANICAL ANALYSIS

Barefoot running vs running shoes

Barefoot running has increased in popularity over recent years, risks and benefits have been widely speculated in current literature. However, there is insufficient evidence on potential advantages and disadvantages of barefoot running. The purpose of this article was to systematically review the recent literature about barefoot running to evaluate the biomechanical measurements and the influence of foot strike modalities compared to shod running.

Barefoot running is characterized by the absence of external protection and minimal cushioning against the ground, being its main difference with the cushioned race the part of the foot that first contacts the ground. Barefoot runners usually land with the front foot or forefoot before lowering the heel, but sometimes land with a flat foot or midfoot or, less frequently, with the heel or rearfoot. On the other hand, mostly shod runners, land with the rearfoot facilitated by the raised heel and the padding of modern footwear (1).

Differences in race conditions and foot strike can be related to possible spatio-temporal, kinematic and muscle activity changes between one group and another of runners.

Biomechanics Analysis

The knee must absorb less energy in barefoot running and, on the contrary, the ankle absorbs more energy in barefoot running midfoot and forefoot. The angles of the ankle when landing forefoot are plantar flexion compared to dorsiflexion in the rearfoot strike. The gastrocnemius suffer greater muscular activity in the forefoot and midfoot group, and the tibialis anterior is more active in the rearfoot group. In addition, the centre of mass is more advanced and the cadence increases in barefoot running.

 

Foot strike

Spatio-temporal Variables

In all the reviewed studies there is homogeneity regarding the effect on the speed variable, it was observed that both the footwear and the type of strike do not influence the running speed. However, the stride length was significantly shorter in barefoot running but it is compensated by an increase in the cadence, which results in a decrease in the support and oscillation phase. According to previous studies, it can be considered that the increase in cadence can be an effective strategy to reduce the loads to which the knee is subjected, and it could be useful in the modulation of biomechanical factors that can contribute to patellofemoral pain (2).

Speed - Cadence - Stride phases

The impact and load rate suffered by the body during the race must be distributed by the absorption mechanisms inherently possessed by the body against this potential damage, through active absorption (with joint alignment and muscular forces) or passive absorption (through of the heel pad, synovial fluid, bone and articular cartilage) (3). Studies show that during the road race the knee absorbed more energy than the ankle in all foot strike conditions. However, in barefoot running with support in midfoot and forefoot this absorption is reversed and the ankle becomes the joint that absorbs the most load, better for the knee that absorbs less energy. Since in barefoot running the force of impact and the load rate are lower compared to shod running and with forefoot strike is less than rearfoot, the knee is the most benefited in this condition and this type of foot strike.

The cushioning found in modern footwear is designed to attenuate and reduce the forces of impact, the shoe sole being an element that contributes to reduce pressure by using materials and concrete geometry depending on the pattern of the corridor (34). However, it has been observed that 85% of shod runners use a rearfoot strike, which may derive from the design of the footwear and, ultimately increase the mechanical load in the lower extremity as the rearfoot strike group which has the greatest impact (1, 4, 5).

In contrast, the tibial impact was greater in the barefoot forefoot strike, with high impact rates associated with the appearance of race associated injuries such as tibial stress fracture and tibial periostitis (6, 7), which is why It is necessary to delve into this topic, since only one study showed this information. Similarly, there are discrepancies in the literature because according to Williams et al. (8) the type of forefoot strike reduces the tibial impact in barefoot running, and according to Olin et al. (9) the tibial impact time was significantly shorter in this race modality. In addition, it has been observed that certain types of heel wedges can increase tibial stress (4).

The impulse and the plantar pressure peak are greater in the first and second metatarsals in the barefoot forefoot strike, may be associated with stress fractures when the transition from shod running is made quickly (10). Likewise, the current footwear has reinforcement in the midsole of this region to reduce the impact (4).

Foot strike impact

Cinematic Variables

The biomechanics of the lower limb can be influenced by the type of foot strike and by running conditions. There were significant differences in range of motion of the ankle and knee in both running conditions, but there was no homogeneity in the hip literature. The angles of the ankle at forefoot strike landing are plantar flexion compared to dorsiflexion in the rearfoot strike. In the forefoot strike, the foot lands first with a plantar flexion posture followed by a dorsiflexion movement that is controlled by the eccentric contraction of the leg muscles, serving as a buffer for the runners and this range of motion being greater in the condition barefoot. The angles of the knee when landing forefoot strike are greater in flexion in both barefoot and shod running, in addition the angle of knee more flexed in the initial contact provides a greater cushioning effect. All this is because if the ankle is in a greater plantar flexion in the initial contact, the knee will be more flexed to establish the hitting position closer to the centre of mass projection (8).

Range of motion barefoot landing phase

Muscle Activity

For the normally runners with shoes, the biggest challenge in the change to the forefoot strike may be the increasing activity of the gastrocnemius during the support phase. Based on electromyographic signals (9, 11, 12), the gastrocnemius show a significantly higher forefoot strike than rearfoot strike activity in preactivation and support phases. Considering the observed results, it is necessary to advise the runners to carry out an adequate training of the gastrocnemius to provide adequate cushioning. However, excessive training could cause a high load of this musculature increasing the risk of suffering injuries to the Achilles tendon (13).

Muscle activity

Injuries

The main question in the mind of runners, coaches and physiotherapists is whether the barefoot running has any effect on the ratio of injuries. The positive effects of the barefoot running have been widely speculated, but there is an ongoing debate about the advantages and potential dangers of the barefoot running and the adaptation of a barefoot running style. The interpretation of this type of studies comparing barefoot running with modern shoes is that the loads are lower in certain areas, but higher in others. For example, Shih et al. (11) showed that the load on the knee was lower running barefoot, but the load on the ankle was greater. While Thompson et al. (14) showed that the heel impact was reduced by running barefoot and Olin et al. (9) indicated that the tibial load was greater in the group of barefoot runners. This means that the load is transferred from one place to another, there being no systematic benefit of one over the other. This can have specific individual benefits, not extrapolated to everyone. A higher load on one type of tissue may increase the risk of injury in some individuals, but not in others.

Patients with knee pain would benefit more from one style than another due to the loads. If the shod runners manifest an increase in symptoms on or around the knee, you should consider changing your foot strike to a mid-forefoot pattern or even attempting the barefoot running. Conversely, barefoot running tends to increase the impact load around the lower leg and ankle, which increases the risk of injury in this anatomical region.

In this scenario, the runner should be advised to change to a rearfoot strike or even try different shoes. Finally, the transition to the barefoot running from the road must proceed with caution to avoid injury.

Knee injuries

Conclusion

The barefoot running can modify biomechanical parameters of the race compared to shod running; being the most remarkable: the cadence, the load rate, the absorption of energy, the ROM of the ankle in the support phase and the muscular activity of the gastrocnemius.Possibly, the most relevant factor in the biomechanical modifications that are observed in the barefoot running is the type of foot strike, which is normally done with forefoot.

Forefoot strike

Rearfoot strike

Bibliography 

1. Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D'Andrea S, Davis IS, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 2010 Jan 28;463(7280):531-5.

2. Lenhart RL, Thelen DG, Wille CM, Chumanov ES, Heiderscheit BC. Increasing running step rate reduces patellofemoral joint forces. Med Sci Sports Exerc. 2014 Mar;46(3):557-64.

3. Ly QH, Alaoui A, Erlicher S, Baly L. Towards a footwear design tool: influence of shoe midsole properties and ground stiffness on the impact force during running. J Biomech. 2010 Jan 19;43(2):310-7.

4. Fernández Villarejo M, Gijón Nogueron G. Factores del calzado deportivo de carrera que influyen en la práctica deportiva: revisión sistemática. Arch med deporte. 2014:105-10.

5. Lieberman DE, Castillo ER, Otarola-Castillo E, Sang MK, Sigei TK, Ojiambo R, et al. Variation in Foot Strike Patterns among Habitually Barefoot and Shod Runners in Kenya. PLoS One. 2015;10(7):e0131354.

6. Milgrom C, Finestone A, Segev S, Olin C, Arndt T, Ekenman I. Are overground or treadmill runners more likely to sustain tibial stress fracture? Br J Sports Med. 2003 Apr;37(2):160-3.

7. Fredericson M, Bergman AG, Hoffman KL, Dillingham MS. Tibial stress reaction in runners. Correlation of clinical symptoms and scintigraphy with a new magnetic resonance

8. Williams DS, 3rd, Green DH, Wurzinger B. Changes in lower extremity movement and power absorption during forefoot striking and barefoot running. Int J Sports Phys Ther. 2012 Oct;7(5):525-32.

9. Olin ED, Gutierrez GM. EMG and tibial shock upon the first attempt at barefoot running. Hum Mov Sci. 2013 Apr;32(2):343-52.

10. Murphy K, Curry EJ, Matzkin EG. Barefoot running: does it prevent injuries? Sports Med. 2013 Nov;43(11):1131-8.

11. Shih Y, Lin KL, Shiang TY. Is the foot striking pattern more important than barefoot or shod conditions in running? Gait Posture. 2013 Jul;38(3):490-4.

12. Sinclair J, Atkins S, Richards J, Vincent H. Modelling of Muscle Force Distributions During Barefoot and Shod Running. J Hum Kinet. 2015 Sep 29;47:9-17.

13. Lieberman DE. What we can learn about running from barefoot running: an evolutionary medical perspective. Exerc Sport Sci Rev. 2012 Apr;40(2):63-72.

14. Thompson MA, Lee SS, Seegmiller J, McGowan CP. Kinematic and kinetic comparison of barefoot and shod running in mid/forefoot and rearfoot strike runners. Gait Posture. 2015 May;41(4):957-9.

Barefoot vs running shoes Running shoes Barefoot running Running Shod running Biomechanics Foot wear Forefoot strike Midfoot strike Rearfoot strike Strike Cinematic Injuries Injury Muscle activity Spatio-temporal