8 98 Board #5 June 1, 9:30 AM - 11:30 AM The Effect Of Minimal Running Shoes On Peak VO2 And 5 Km Running Performance Elias Zacharogiannis, Prokopios Chatzakis, Giorgos Paradisis, Maria Maridaki. Athens University, Athens, Greece. Email: elzach@phed.uoa.gr (No relationships reported) Introduction: Barefoot running may affect performance in endurance running events, by improving biomechanical parameters and physiological responses compared to shod running. The majority of research efforts during the last 15 years have been centered mainly on the biomechanical differences between shod and unshod running and the influence on a selection of physiological variables i.e. heart rate, submaximal oxygen uptake and blood lactate. Surprisingly data from studies to examine the impact of barefoot running on the race performance are scarce. PURPOSE: The purpose of this study is to examine the effect of minimal running shoes (MRS) on peak oxygen consumption (peakVO2) and 5 km running performance. METHODS: Twelve moderately trained subjects (10 male, 2 female), all habitual shod runners, participated in a series of 5 maximal trials 7 days apart. During the first two trials, the subjects completed two exhaustive incremental peakVO2 efforts on a treadmill, running either with MRS or with their shoes in a random order. On Day 3 they completed a 3 km race on a treadmill running with the MRS, for familiarization with the race performance trial. During the last two laboratory visits, the subjects completed two 5 km race trials on a treadmill, either with the MRS or the shod condition in a random order. Paired T-test for dependent samples was used for the statistical analysis. RESULTS: Mean (±sd) MRS and shod running peakVO2 values 54.68 ± 3.74 and 54.04 ± 4.44 ml.min-1.kg-1 respectively was not different (p=0.532). Mean (±sd) time for the 5 km race performance also was not different (p=0.225) between MRS and shod conditions (1446 ± 139,22 v 1458 ± 141,05 s). CONCLUSIONS: The results of the present study show no effect of MRS in habitually shod runners on peakVO2 and 5 km performance time. Despite however, the lack of significance there was a tendency for faster times with MRS condition. Future studies may need to extend the familiarization period with MRS to notice significant running performance benefits. 99 Board #6 June 1, 9:30 AM - 11:30 AM 8 Week Exercise Protocol and Minimalist Shoes Walking Effect on Lower Leg Muscle Size Aaron W. Johnson 1 , Tiffany D. deVries 1 , Shaun Brewer 1 , Andrew Rich 1 , Joseph W. Myrer 1 , Irene S. Davis, FACSM 2 , Sarah T. Ridge 1 . 1 Brigham Young University, Provo, UT. 2 Harvard Medical School, Boston, MA. (Sponsor: Irene S. Davis, FACSM) (No relationships reported) Transitioning to minimalist shoes (MS) is desired by many runners. However, there are concerns about transitioning safely. Pre-transition exercises or low intensity training may facilitate this transition. PURPOSE: The purpose of this preliminary study was to investigate muscle size change after either 8 weeks of walking in MS or 8 weeks of following an exercise protocol. The muscles of interest in the lower leg were the tibialis anterior (TA), tibialis posterior (TP) and flexor digitorum longus (FDL). METHODS: 28 runners (22.6±2.6 yr, 174.4±10.3 cm, 70.0±13.0 kg) continued to run their usual weekly amount and were randomly assigned to a control group (n=7), MS walking group (n=7, progressively increase walking from 2500 steps in MS to 7000 steps/day at 8 weeks), or an exercise group (n=14, 8 weeks of progressive foot muscle exercises). Videos of the TA, TP and FDL were taken starting from a relaxed state to a contracted state and back to the relaxed state via B-mode ultrasound imaging using a 10 MHz linear probe (GE LogiqP6). Videos for the FDL were taken at a point 50% distal from the medial knee joint line to the inferior tip of the medial malleolus with the probe held perpendicular to the shaft of the leg. For the TP and TA the probe was held at a point 30% from the knee joint line to the inferior tip of the lateral malleolus. To obtain videos of the TA and TP, each participant was instructed to invert their foot. For the videos of the FDL, participants were instructed to flex their toes. Videos of the contraction cycle for the TA, TP, and FDL were recorded. 2 separate still-shots of the muscles at rest were saved from the recorded videos to make size measurements. Repeated measures ANCOVA with the respective baseline muscle size as covariate was run. RESULTS: There was a significant main effect for time for all muscles (p<0.02), and a significant group by time interaction (p<0.05) for the change in muscle size for the FDL and TP. The mean and SD for the muscles were TA: 2.5±0.3 cm, TP: 1.8±0.25 cm, FDL: 1.7±0.36 cm2. CONCLUSION: The data from this preliminary study appear to support the idea that walking in MS or performing foot intrinsic strengthening exercises may increase the size of some lower leg muscles. It is unknown if this increase in muscles size will alter the potential risks associated with a transition to minimalist shoe running. 100 Board #7 June 1, 9:30 AM - 11:30 AM The Effect Of Extreme Cushioning Shoes On Running Economy At Different Speeds And Inclines Miles A. Mercer, Tori Stone, Jack Young, FACSM, John Mercer, FACSM. University of Nevada, Las Vegas, Las Vegas, NV. (Sponsor: John Mercer, FACSM) Email: mercerm@unlv.nevada.edu (No relationships reported) Running economy is defined as the oxygen cost for running at a given submaximal speed. Several factors related to shoe design can affect running economy such as shoe mass and cushioning. While shoe mass has been shown to increase the metabolic cost of running, the effect of shoe cushioning on running economy is less clear. PURPOSE: To determine the effect of wearing extreme cushioning shoes on running economy at different speeds and inclines. METHODS: Subjects (n=10, age 28.7±6.4 yr, weight: 67.8±10.4 kg, height: 1.72±0.09 m) were fitted with a pair of neutral running shoes (Addidas Prene) and a pair of extreme cushioning shoes (Hoka Bondi 4). Each subject completed two days of testing. Day 1: Subjects ran on a treadmill at three speeds (preferred speed (PS), PS+1 mph, PS-1 mph) in each shoe condition (6 total conditions). Day 2: Subjects ran on a treadmill at two different inclines (0%, 6%) in each shoe condition (4 total conditions). For all conditions, subjects ran for 8-10 minutes while rate of oxygen consumption (VO 2 ) was recorded (Moxus). Average VO 2 during each condition was calculated and compared Day 1 using a 2 (shoe) x 3 (speed) and Day 2 using a 2 (shoe) x 2 (incline) repeated measures ANOVA (α=0.05). RESULTS: VO 2 was not influenced by the interaction of speed and shoe (p=0.496). VO 2 was different between speeds (increasing on average 30.7% across speeds; p<0.001) but not between shoes (p=0.191). VO 2 was not influenced by the interaction of incline and shoe (p=0.054). VO 2 was greater for incline (increasing on average 40.0% with incline; p=0.017) but not different between shoes (p=0.059). CONCLUSIONS: : It seems that the cushioning of the shoe (extreme vs. regular) play no role in the influence of running economy. 101 Board #8 June 1, 9:30 AM - 11:30 AM Running Shoe With Extra Midsole Thickness Increase Foot Horizontal Instability During Treadmill Running Shuqi Zhang 1 , Li Li, FACSM 2 . 1 Northern Illinois University, Dekalb, IL. 2 Georgia Southern University, Statesboro, GA. (No relationships reported) Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.