Commercially available fitness trackers have been found to accurately measure steps and caloric expenditure during walking and running activities. Circuit-style, highintensity functional training (HIFT) has become increasingly popular because it is inexpensive and effective in improving muscular strength and cardiovascular fitness. PURPOSE: To evaluate the accuracy of five accelerometers (ActiGraph GT3X, Nike Fuelband, Fitbit One, Fitbit Charge HR, and Jawbone UP Move) in estimating energy expenditure while performing an acute bout of HIFT. METHODS: Participants (n = 47) underwent baseline testing and at least 48 hours later, each participant completed the main test: a 15-minute workout consisting of 12 repetitions each of 7 different exercises; performed circuit-style by completing as many rounds as possible. During the main test, each participant wore the Cosmed K4b2 portable metabolic analyzer (PMA) and five different accelerometers. RESULTS: Four of the five fitness trackers reported lower (p <0.01) total caloric expenditure values compared to the PMA during the acute bout of HIFT. The waist-mounted device (ActiGraph, 182.55 ± 37.93 kcals) most closely mimicked caloric expenditure compared to the PMA (Cosmed, 144.99 ± 37.13 kcals) as indicated by an insignificant p value (0.056). Systematic differences between the activity monitors were calculated using an Intraclass Correlation (ICC) with an ICC = -0.032. The ICC of F (46,235) = 0.812 (p = 0.799) was not significant at the predetermined 0.05 alpha level. A Repeated Measures ANOVA showed that when compared to the Cosmed, all activity monitors were significantly different at the 0.05 alpha level. The Fitbit One and the Fitbit Charge HR were the only two activity monitors that are not significantly different from one another (p = 0.985). The range of error based on mean absolute percentage errors (MAPE) was lowest for the ActiGraph (15.1%) and highest for the Fitbit Charge HR (22.1%). CONCLUSION: The wrist- and hip-mounted fitness trackers do not accurately assess energy expenditure during HIFT exercise. Supported by: WKU Graduate School, NIGMS 2P20 GM103436-14; Institutional Development Award (IDeA) from National Institute of General Medical Sciences, National Institutes of Health, 5P20GM103436 and the WKU RCAP Grant 14-8007.

Introduction: Crossfit is a modern sport that yearly expands worldwide. The goal of the sport is to develop performance and fitness so athletes can optimize their performance in many training categories. Furthermore, the sports WOD:s is complex, where many physiological challenges occur. The athlete is forced to push their limits of the movements, where there is a possibility for failure between the muscle fibers activation and synchronization. This can risk the sports security regarding injuries because of insufficient motor performance. A study from 2014 estimate the injury prevalence in crossfit to be 20%. Meanwhile a study from 2017 showed that the injury prevalence increased to 31,91%. Method: The objective of this study was to examine the crossfit athlete background, injury prevalence and injury categories between oktober 2016 - april 2017 in Sweden. A Brazilian survey was used in this study. The survey was modified and translated to Swedish before administered to certified crossfit facilities around the country. The method for this study used a descriptive cross-sectional design with a quantitative distribution of an online survey. Result: The common crossfit athlete is preferably 32 years or older, had a sedentary work and strict training routines with years of experience. Furthermore, 58 of 190 participants sustained a total of 87 injuries the past 6 month. This correlates to an injury prevalence of 30,5% for the crossfit athletes in Sweden. Furthermore, the most common injury categories were located on the neck/spine (21,84%), shoulder (18,39%), skeletal muscle (16,09%) and knee (16,09%). Therefore, the sport can cause different injuries throughout participation. Conclusion: Due to a high injury prevalence and a wide variation of injuries does the sport show a high injury risk, despite the athletes training experience. It takes more research to know the exact mechanisms for the injuries and how they can be prevented. / Introduktion: Crossfit är en nykommen sport somårligen växer världen över. Sporten syftar till att förbättra prestation och fitness i medvetenhet att optimera kompetens i alla fysiska kvalitéer. Dock finns det en komplexitet med att inkludera flera fysiska utmaningar i träningen. Utövaren tvingas utföra rörelserna med maximal insats för att inte misslycka samspelet mellan muskelfibrernas aktivering och synkronisering. Sådana misslyckanden kan äventyra säkerheten på grund av otillräcklig motorisk prestation. Studier från andra länder har uppmärksammat crossfitens skadeprevalens de senaste åren. Första studien från 2014 visar en prevalens på 20%, medan nyaste studien från 2017 visar en prevalens på 31,91%. Syfte: Denna studie har undersökt Sveriges crossfitutövares bakgrund, skadeprevalens och skadekategorier mellan oktober 2016 t.o.m. april 2017. Metod: Studien har använt en kvantitativ tvärsnittsstudie genom elektroniska enkäter. Enkäten har ursprung från en Brasiliansk studie som modifierades till svenska. Enkäten blev e-postad till Sveriges certifierade anläggningar i syfte att vidarebefordra enkäten till utövarna. Resultat: Studien bygger på 190 fullständiga enkätsvar som har generaliserats till Sveriges crossfitutövare. Resultatet visade att den generella crossfitutövaren ofta är över 32 år, har ett stillasittande yrke samt strikta träningsrutiner och många års träningserfarenheter, både inom och utanför crossfit. Skadeprevalensen visade att 30,5% av utövarna hade skadat sig de senaste 6 månaderna, då skadorna var lokaliserat på flera delar av kroppen. Vanligaste var nack-/rygg-(21,84%), axel-(18,39%), muskel-(16,09%) och knäskada (16,09%). Slutsats: Studien visade att Crossfitutgör en skaderisk trots erfaren träningsbakgrund. Men det krävs utförligare forskning för att kunna tyda de exakta mekanismerna för skadeuppkomsten. Det är viktigt att studier utförs för att förbättra sportens säkerhet eftersom anläggningar/organisationer ökar och forskning saknas.