Inertial measurement units (IMUs) can be used to monitor running biomechanics in real-world settings, but IMUs are often used within a laboratory. The purpose of this scoping review was to describe how IMUs are used to record running biomechanics in both laboratory and real-world conditions. We included peer-reviewed journal articles that used IMUs to assess gait quality during running. We extracted data on running conditions (indoor/outdoor, surface, speed, and distance), device type and location, metrics, participants, and purpose and study design. A total of 231 studies were included. Most (72%) studies were conducted indoors; and in 67% of all studies, the analyzed distance was only one step or stride or <200 m. The most common device type and location combination was a triaxial accelerometer on the shank (18% of device and location combinations). The most common analyzed metric was vertical/axial magnitude, which was reported in 64% of all studies. Most studies (56%) included recreational runners. For the past 20 years, studies using IMUs to record running biomechanics have mainly been conducted indoors, on a treadmill, at prescribed speeds, and over small distances. We suggest that future studies should move out of the lab to less controlled and more real-world environments.

/pdf/is-this-the-real-life-or-is-this-just-laboratory-a-scoping-373ign4i.pdf

Is This the Real Life, or Is This Just Laboratory? A Scoping Review of IMU-Based Running Gait Analysis

Running gait assessment has traditionally been performed using subjective observation or expensive laboratory-based objective technologies, such as three-dimensional motion capture or force plates. However, recent developments in wearable devices allow for continuous monitoring and analysis of running mechanics in any environment. Objective measurement of running gait is an important (clinical) tool for injury assessment and provides measures that can be used to enhance performance.We aimed to systematically review the available literature investigating how wearable technology is being used for running gait analysis in adults.A systematic search of the literature was conducted in the following scientific databases: PubMed, Scopus, Web of Science and SPORTDiscus. Information was extracted from each included article regarding the type of study, participants, protocol, wearable device(s), main outcomes/measures, analysis and key findings.A total of 131 articles were reviewed: 56 investigated the validity of wearable technology, 22 examined the reliability and 77 focused on applied use. Most studies used inertial measurement units (n = 62) [i.e. a combination of accelerometers, gyroscopes and magnetometers in a single unit] or solely accelerometers (n = 40), with one using gyroscopes alone and 31 using pressure sensors. On average, studies used one wearable device to examine running gait. Wearable locations were distributed among the shank, shoe and waist. The mean number of participants was 26 (± 27), with an average age of 28.3 (± 7.0) years. Most studies took place indoors (n = 93), using a treadmill (n = 62), with the main aims seeking to identify running gait outcomes or investigate the effects of injury, fatigue, intrinsic factors (e.g. age, sex, morphology) or footwear on running gait outcomes. Generally, wearables were found to be valid and reliable tools for assessing running gait compared to reference standards.This comprehensive review highlighted that most studies that have examined running gait using wearable sensors have done so with young adult recreational runners, using one inertial measurement unit sensor, with participants running on a treadmill and reporting outcomes of ground contact time, stride length, stride frequency and tibial acceleration. Future studies are required to obtain consensus regarding terminology, protocols for testing validity and the reliability of devices and suitability of gait outcomes.CRD42021235527. 

https://link.springer.com/content/pdf/10.1007/s40279-022-01760-6.pdf

Wearables for Running Gait Analysis: A Systematic Review

We aimed to (i) determine self-reported injury and illness frequency in trail runners 4 weeks preceding competition; (ii) compare athletes with and without injury/illness by sex, age, body mass index (BMI) and competition distance; (iii) describe mechanism of injury, anatomical region (injury)/organ system (illness) involved, consequences of injury on preparation and self-perception of injury severity; (iv) compare anatomical region (injury) and organ system (illness) by sex. A total of 654 trail runners (age 36.2, IQR 30.6–43.0; 36.9% females) participated in this retrospective cross-sectional study by completing a self-reported questionnaire. Injury and illness frequency rates were 31.3% (n = 205, CI: 27.7–35.0%) and 22.3% (n = 146, CI: 19.1–25.7%), respectively. No significant difference was found between injured vs. non-injured or ill vs. non-ill study participants by sex, age, BMI and competition distance. Regarding injuries, gradual onset (41.6%) and knee (33.2%) were the most indicated mechanism and anatomical region of injury. At least 85.4% of trail runners changed their training following injury and 79% indicated that their injury would affect their competition performance. Regarding illness, the respiratory tract was the most frequent organ system involved (82.9%). Male and female participants reported similar proportions of anatomical regions (injury) and organ systems (illness) affected. These results could help to generate education strategies and appropriate medical support before and during these competitions.

Frequency of Injury and Illness in the Final 4 Weeks before a Trail Running Competition

The purpose of this research was to analyze the organizational structures of the different federations and entities representing the modalities of trail-running, skyrunning, and mountain running and how they have settled in the current sports landscape. The main task of these entities is to act as hosts of the legally established modalities, both internationally and nationally, applying their respective regulations and statutes unilaterally. Through an in-depth review of the different regulations, statutes, and current articles of all the organizations that represent the different disciplines, we can observe how a sport modality that seems to be the same is nevertheless distant in its execution (regulations, championships, classifications, systems of points, etc.), which has led to the international level being established in different sport modalities (trail running and skyrunning). At the level of the Spanish territory, it has led to an administrative dispute to know who has the powers to approve sports competitions.

/pdf/review-of-the-organizational-structures-of-the-trail-running-3b7mqkxd.pdf

Review of the Organizational Structures of the Trail Running, Skyrunning and Mountain Running Modalities in Spain

Our purpose with this study was to analyze trail runners’ psychological variables of mental toughness (MT) and resilience, and their associations with runners’ performances within a quantitative cross-sectional study. In total, we analyzed data from 307 Portuguese trail runners (60 female, 247 male), aged between 20 to 66 years (M age = 41.98; SD = 7.74). The results showed that the measurement model, including the factors of MT, resilience, and performance variables, exhibited an adequate fit to the data: χ 2 = 150.01 (74); BS-p = .003; CFI= .953; TLI = .942; RMSEA = .058 90% (.045, .071) and SRMR= .042. Standardized direct effects revealed positive associations between these variables. More specifically: (a) MT was significantly associated with resilience; and (b) resilience was significantly associated with performance. The indirect regression paths showed that MT was positively associated with performance, with resilience considered a possible mediator (β = .09 IC = .010, .168; p = .02). In total, considering direct and indirect effects, the model explained 21% of performance variance among trail runners.

https://doi.org/10.1177/00315125231165819

Mental Toughness and Resilience in Trail Runner’s Performance

The recent popularity of trail running and the use of portable sensors capable of measuring many performance results have led to the growth of new fields in sports science experimentation. Trail running is a challenging sport; it usually involves running uphill, which is physically demanding and therefore requires adaptation to the running style. The main objectives of this study were initially to use three “low-cost” sensors. These low-cost sensors can be acquired by most sports practitioners or trainers. In the second step, measurements were taken in ecological conditions orderly to expose the runners to a real trail course. Furthermore, to combine the collected data to analyze the most efficient running techniques according to the typology of the terrain were taken, as well on the whole trail circuit of less than 10 km. The three sensors used were (i) a Stryd sensor (Stryd Inc., Boulder, CO, USA) based on an inertial measurement unit (IMU), 6 axes (3-axis gyroscope, 3-axis accelerometer) fixed on the top of the runner’s shoe, (ii) a Global Positioning System (GPS) watch and (iii) a heart belt. Twenty-eight trail runners (25 men, 3 women: average age 36 ± 8 years; height: 175.4 ± 7.2 cm; weight: 68.7 ± 8.7 kg) of different levels completed in a single race over a 8.5 km course with 490 m of positive elevation gain. This was performed with different types of terrain uphill (UH), downhill (DH), and road sections (R) at their competitive race pace. On these sections of the course, cadence (SF), step length (SL), ground contact time (GCT), flight time (FT), vertical oscillation (VO), leg stiffness (Kleg), and power (P) were measured with the Stryd. Heart rate, speed, ascent, and descent speed were measured by the heart rate belt and the GPS watch. This study showed that on a ≤10 km trail course the criteria for obtaining a better time on the loop, determined in the test, was consistency in the effort. In a high percentage of climbs (>30%), two running techniques stand out: (i) maintaining a high SF and a short SL and (ii) decreasing the SF but increasing the SL. In addition, it has been shown that in steep (>28%) and technical descents, the average SF of the runners was higher. This happened when their SL was shorter in lower steep and technically challenging descents.

Noé Perrotin

Papers

Biomechanics of Trail Running Performance: Quantification of Spatio-Temporal Parameters by Using Low Cost Sensors in Ecological Conditions