1. The right foot forward, or the right shoe?
A comparative review of barefoot and shod running.

2. 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

3. Studies suggest that barefoot runners:
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:
Strike the ground with a more plantarflexed foot
Increase stride frequency and decrease contact time
Decrease stride length
Experience reduced impact forces
Plantar flexed
Stride length
Impact forces

4. 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 ) English 3) At least one subject group of barefoot runners
Exclusion criteria: 1) Published before )Trials included only barefoot walkers or shod runners
63 papers found.
39 met inclusion/exclusion criteria
In order to investigate the validity the four characteristics of barefoot running and the proposed benefits of running shoes: introduce bulletpoints

5. 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
Arun: explain the image= barefoot heel-strike running gait, 8 areas identified.
Bulletpoint 3=De Cock et al attribute this shortening to the activation of the intrinsic muscles of the foot, normally inactive in shoes.

6. 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

7. Results: Muscle Activation
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

8. 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.

9. 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

10. Discussion Biomechanical 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

11. 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?

12. 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?

13. Further Research Barefoot Running as a social phenomenon
Differential diagnoses:
1.Bacterial and fungal infections (i.e. osteomyelitis)
2.Increased need for wound care education
3.Frostbite