The right foot forward, or the right shoe?

A comparative review of barefoot and shod running.

Research Question

Hypothesis: There are biomechanical differences between shod

and barefoot running.Null Hypothesis: There are no biomechanical differences between

shod and barefoot running.

To investigate this…We performed a literature review

Background• Proposed benefits of modern running

shoes include stability, cushioning, performance and injury reduction

• Running shoes have a short history. Prior to their introduction humans ran barefoot

Studies suggest that barefoot runners:

1. Strike the ground with a more plantarflexed foot

2. Increase stride frequency and decrease contact time

3. Decrease stride length4. Experience reduced impact forces

Stride length

Plantar flexed

Impact forces

Methods

• Literature pertaining to barefoot running was found on the NIH PubMed database

• Search Terms: “bare foot”, “barefoot”, “barefeet” and “bare feet” in title/abstract. MeSH: “running”

• Inclusion criteria: 1) Published after 1985 2) English 3) At least one subject group of barefoot runners

• Exclusion criteria: 1) Published before 1985 2)Trials included only barefoot walkers or shod runners

• 63 papers found. • 39 met inclusion/exclusion criteria

Results: Impact and loading patterns•75-91% habitually barefoot runners FFS•Approximately 85% of shod runners RFS• Increased cadence, decreased contact time, shorter stride length•Barefoot: Peak pressures under heel and 2nd met. Highest impulse under 2nd met, lowest impulse under heel •Shod: Peak pressures under heel, midfoot and hallux. Highest impulse under heel•Ground Reaction Forces• Barefoot rearfoot strike (RFS): highest

impact transient• Shod RFS: distinct impact transient• Barefoot forefoot strike (FFS): minimal

impact transient• Peak GRF similar

Results: Joint Movement and Coupling• Barefoot: Significantly more plantarflexed foot at contact

regardless of footstrike pattern. Increasing plantarflexion with barefoot accommodation– Suggestive of reduced rearfoot and forefoot frontal plane

motion– Reduced eversion velocity

• Shod: Dorsiflexed foot at contact– Suggestive of greater rearfoot and forefoot frontal motion– Increased eversion velocity– Increased hip internal rotation and knee varus torques

• Rearfoot-tibial coupling unchanged by condition.• Sagittal plane knee motion is inconsistent

Barefoot• Gastroc-soleus: stronger, earlier activation (regardless of footstrike pattern)•Tibialis Anterior: stronger, and earlier activation (post-heel-strike)•Spinal Muscles: increase in loading rate, increase in response time to heel-strike, and decrease in time interval between peak lumbar acceleration and peak lumbar muscle response.•Medial Longitudinal Arch: significantly shortens with increased weight bearing activity. Shod•Tibialis Anterior: stronger (pre-heel-strike)•Peroneus Longus: increased activity, based on increased heel height, which everts the shod foot when put under inversion stress

Results: Muscle Activation

Results: Sensitivity and feedback• Unshod runners experience a greater amount

of heel fat pad deformity and compression. (9±5mm versus 5.5±.2mm)

• The heel region of the foot was shown to have the highest pain threshold, the hallux intermediate, while 1st MPJ had the lowest

• Feedback training was tested using peak positive tibial acceleration.

• 70% reduction of peak positive tibial acceleration immediately after one training session.

• 80% reduction ten minutes after 1st feedback training session.

Discussion• Barefoot runners have a characteristically different gait

pattern than shod runners– Forefoot strike, faster cadence, decreased contact time,

shorter strides• Impact reduction and efficiency improvement– Dissipates impact forces in the sagittal plane– Greater elastic return in Achilles tendon– Reduced weight

• Heel striking appears to translate impact forces into excessive rearfoot pronation, tibial rotation, and possibly knee flexion

DiscussionBiomechanical model of barefoot gait

• Forefoot strike at lateral forefoot. Preactivated gastroc-soleus• Mild forefoot pronation followed by controlled heel

contact and mild rearfoot pronation• Metatarsal splay• Neutral midstance. • Greater potential energy storage in Achilles tendon• Reduced overall contact time• Mild rearfoot and forefoot inversion at toeoff.• Reduced stride length. Increased cadence

Discussion• Running efficiency was found to

be influenced by, not just shoe mass, but shoe shape (proven using a thin, flexible, foot covering of the same weight as a shoe).

• Heel height may reduce efficiency. Are minimal shoes a solution?

• Does barefoot running or a forefoot strike reduce injury risk?

• What are the tradeoffs?

Future Research Opportunities• No injury data available• Longitudinal study of injuries in

barefoot and shod runners: fat pad atrophy, ground reaction forces

• Control for mileage and intensity

• Testing foot intrinsic muscle strength

• Literature has yet to look at minimalist shoe design (minimal cushion and low heel lift)

• Are the major manufacturers (i.e. Nike, Asics, Brooks) looking at current research?

Further ResearchBarefoot Running as a social phenomenon •Differential diagnoses:1.Bacterial and fungal infections (i.e. osteomyelitis) 2.Increased need for wound care education3.Frostbite