Greater Ankle Plantar Flexor Work Is Predictive of Better Running Economy on Steep Uphill Grades.

Greater ankle plantar flexor work was predictive of better running economy on a 10% uphill grade.

• β = -3054.56; P = .013 for the relationship between ankle plantar flexor work and running economy at 10% grade
• This relationship was not significant for level ground or 5% grade (P > .05)
• No other joint work, stiffness, or strength factors were related to running economy at any grade
• Twenty-seven recreational runners participated (14 females, age: 33.7 [12.8] y, mass: 70.2 [12.5] kg)

Trail runners demonstrated better running economy on the 10% grade compared with road runners.

• Trail runners showed significantly better 10% grade running economy (P = .015)
• Trail runners also demonstrated greater ankle plantar flexor work (P = .048) compared to road runners
• This finding emerged from a secondary analysis exploring the relationship of training factors to running economy
• Results suggest trail running may lead to specific physiological and biomechanical adaptations beneficial to performance

The study examined lower extremity joint kinetics and muscle strength as predictors of running economy across multiple grades.

• Twenty-seven recreational runners completed laboratory-based running economy, biomechanics, and isokinetic dynamometry testing
• Testing conditions included level ground, 5% grade, and 10% grade
• Linear regression analyses were used to determine the effect of lower extremity joint work, stiffness, and strength on running economy for each grade
• Variables assessed included joint work, stiffness, and strength of the lower extremity

Targeting the energy generation capacity of the plantar flexors may be worthwhile for improving uphill running economy.

• Only ankle plantar flexor work, not other joint work, stiffness, or strength measures, was associated with running economy
• The association was specific to steep uphill (10%) grade running
• The negative beta coefficient (β = -3054.56) indicates that greater plantar flexor work was associated with lower (better) economy values
• The authors suggest this has practical implications for training interventions targeting uphill running performance