• Burke JR
• Papuga MO

• Foot / physiology
• Orthotic Devices
• Running / physiology

Objective: The purpose of the study was to collect preliminary data to address methodological considerations that may impact subject-specific reactions to foot orthotics during running.

Methods: Six endurance-trained recreational runners recruited from a chiropractic college campus wore their preferred running shoes and then inserted either their custom-made orthotics during 1 testing session or their shoe-fitted insoles during the other testing session. Comfort perception was measured for each footwear condition. Measurements of oxygen consumption (Vo₂) at several moderate exercise intensities, to mimic recreational running, generated an individual's economy-of-running line. Predicted running velocity at Vo_2max (vVo_2max) was calculated as an index of endurance performance. Lower extremity muscle activity was recorded. Descriptive statistics, a repeated-measures analysis of variance model, and a paired t test were used to document any systematic changes in running economy, lower extremity muscle activities, and vVo_2max within and across subjects as a function of footwear conditions.

Results: Decreases in Vo₂ at several moderate exercise intensities (F_{(1,5)footwear} = 10.37, P = .023) and increases in vVo_2max (t₅ = 4.20, P = .008) occurred in all 6 subjects while wearing their orthotic intervention vs their shoe-fitted insoles. There were no consistent changes in lower extremity muscle activity.

Conclusions: Methodological decisions to use a sustained incremental exercise protocol at several moderate exercise intensities and to measure comfort perception of a custom-molded foot orthosis were effective at documenting systematic improvements in running economy among the 6 recreational runners tested. The development of a less physically demanding sustained exercise protocol is necessary to determine underlying neuromuscular mechanisms and/or clinical effectiveness of orthotic interventions.

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