The Relationship of Foot Strike Pattern, Shoe Type, and Performance in a 50-km Trail Race.

Recent "in-race" studies have observed the foot strike patterns of runners in traditional road marathon races. However, similar studies have not been conducted for trail runners, which have been estimated to account for 11% of all runners. The purpose of this study was to (a) determine the rear-foot strike (RFS) prevalence in a 50-km trail race and compare with traditional road marathon races; (b) determine if there is a relationship between foot strike and sex in a 50-km trail race; and (c) determine if there is a relationship between foot strike, shoe type, and performance in a 50-km trail race. One hundred sixty-five runners were videotaped at the 8.1-km mark of the 2012 Ice Age Trail 50-km race. Foot strike analysis revealed RFS prevalence of 85.1%, less than previously reported in traditional road marathon races. There was no relationship found between sex and foot strike (p = 0.60). A significant effect of shoe type on foot strike (RFS was less common among runners in minimalist shoes, p < 0.01) and performance (faster runners were more likely to be wearing minimalist shoes, p < 0.01) was observed; however, no association between foot strike and performance was observed (p = 0.83). This study suggests that most trail runners, albeit less than road runners, prefer an RFS pattern, which is accompanied by biomechanical consequences unique from a non-RFS pattern and, therefore, likely carries a unique injury profile. In addition, the findings in this study suggest that minimalist shoes may represent a reasonable training modification to improve performance.

Ketogenic diet for high partial pressure oxygen diving.

INTRODUCTION: A ketogenic diet (KD) may decrease central nervous system oxygen toxicity symptoms in divers, and in view of this implication a feasibility/ toxicity pilot study was performed to demonstrate tolerance of KD while performing normal diving profiles. The exact mechanism of neuroprotection from the KD remains unknown; however, evidence to support the efficacy of the KD in reducing seizures is present in epilepsy and oxygen toxicity studies, and may provide valuable insight in diving activities. METHODS: Three divers (two males and one female ages 32-45 with a history of deep diving and high pO2 exposure) on the KD made dives to varying depths in Hawaii using fully closed-circuit MK-15 and Inspiration rebreathers. These rebreathers have an electronically controlled set point, allowing the divers to monitor and control the oxygen level in the breathing loop, which can be varied manually by the divers. Oxygen level was varied during descent, bottom depth and ascent (decompression). Divers fasted for 12-18 hours before diet initiation. The ketosis level was verified by urinating on a Ketostix (reagent strips for urinalysis). RESULTS/SUMMARY: Ketosis was achieved and was easily monitored with Ketostix in the simulated operational environment. The KD did not interfere with the diving mission; no seizure activity or signs or symptoms of CNS toxicity were observed, and there were no adverse effects noted by the divers while on the KD.

Foot-strike pattern and performance in a marathon.

PURPOSE: To determine prevalence of heel strike in a midsize city marathon, if there is an association between foot-strike classification and race performance, and if there is an association between foot-strike classification and gender. METHODS: Foot-strike classification (forefoot, midfoot, heel, or split strike), gender, and rank (position in race) were recorded at the 8.1-km mark for 2112 runners at the 2011 Milwaukee Lakefront Marathon. RESULTS: 1991 runners were classified by foot-strike pattern, revealing a heel-strike prevalence of 93.67% (n = 1865). A significant difference between foot-strike classification and performance was found using a Kruskal-Wallis test (P < .0001), with more elite performers being less likely to heel strike. No significant difference between foot-strike classification and gender was found using a Fisher exact test. In addition, subgroup analysis of the 126 non-heel strikers found no significant difference between shoe wear and performance using a Kruskal-Wallis test. CONCLUSIONS: The high prevalence of heel striking observed in this study reflects the foot-strike pattern of most mid-distance to long-distance runners and, more important, may predict their injury profile based on the biomechanics of a heel-strike running pattern. This knowledge can help clinicians appropriately diagnose, manage, and train modifications of injured runners.