Biomechanical And Energetic Trends In Response To 8 Weeks Of Training In Advanced Footwear Technology

Following an 8 subject pilot study, a larger cohort of runners completed a training intervention in either Advanced Footwear Technology (AFT) or racing flats (FL). PURPOSE: Investigate long-term effects of running workout footwear (AFT/FL) use on relative running economy (RE), energetic cost (EC), and explore biomechanical trends that explain changes in footwear specific performance. METHODS: Competitive cross country runners (n = 13) completed pre- (PRE) and post-intervention (POST) lab testing in both AFT and FL. They were assigned either AFT or FL for an 8.5 ± 1.0 week intervention. In PRE/POST, runners were instrumented with EMG, a lower body marker set, unilateral hopping leg stiffness was measured, and ran on an instrumented treadmill. Subjects ran 2 x 3-min trials at a self selected race pace (7 min rest), followed by 4 x 5-min trials (5 min rest) at a submaximal pace (RER < 1), in a randomized order. Trial paces were constant in PRE/POST. An ANCOVA was used to test main effects of intervention shoe assignment (AFT/FL) and time point. RESULTS: An “AFT % Benefit” was calculated comparing RE and EC in AFT to FL during PRE/POST. AFT % Benefit increased to a greater extent from PRE to POST in the AFT group measured by RE (0.86 ± 0.47%) and EC (0.97 ± 0.35%) compared to the FL group (RE: 0.25 ± 1.98%; EC: 0.45 ± 2.22%) (Table 1). On average all participants’ RE and EC at their submaximal pace improved from PRE to POST, with the FL group (RE: 2.67 ± 3.22%; EC: 2.01 ± 3.60%) improving more than the AFT group (RE: 0.87 ± 5.20%; EC: 0.95 ± 5.17%). Leg stiffness, EMG, and biomechanical analysis is still in progress. CONCLUSIONS: AFT trained runners improved their AFT % Benefit to a slightly greater extent than FL trained runners, suggesting that training in AFT increases runner’s ability to benefit from the shoe. On average, all runners’ efficiencies improved, with FL trained runners exhibiting slightly greater improvements in overall metabolic efficiency than AFT trained runners.