In-field assessment of change-of-direction ability with a single wearable sensor.

The Agility T-test is a standardized method to measure the change-of-direction (COD) ability of athletes in the field. It is traditionally scored based on the total completion time, which does not provide information on the different CODs. Augmenting the T-test with wearable sensors provides the opportunity to explore new metrics. Towards this, data of 23 professional soccer players were recorded with a trunk-worn GNSS-IMU (Global Navigation Satellite System-Inertial Measurement Unit) device. A method for detecting the four CODs based on the wavelet-denoised antero-posterior acceleration signal was developed and validated using video data (60 Hz). Following this, completion time was estimated using GNSS ground speed and validated with the photocell data. The proposed method yields an error (mean ± standard deviation) of 0 ± 66 ms for the COD detection, - 0.16 ± 0.22 s for completion time, and a relative error for each COD duration and each sequential movement durations of less than 3.5 ± 16% and 7 ± 7%, respectively. The presented algorithm can highlight the asymmetric performance between the phases and CODs in the right and left direction. By providing a more comprehensive analysis in the field, this work can enable coaches to develop more personalized training and rehabilitation programs

Key Nutritional Considerations for Youth Winter Sports Athletes to Optimize Growth, Maturation and Sporting Development.

Despite a wealth of sport nutrition guidelines for adult athletes, there are currently no nutrition guidelines for youth winter sports athletes. Whilst it may be pragmatic to apply nutrition guidelines for adult athletes to youth winter sports athletes, it is inappropriate. Due to a paucity of research on youth athletes, it is impossible to provide evidence-based guidelines for this population, so careful extrapolation from the theoretical and practical considerations that apply to other athletic groups is necessary. Youth winter sport athletes undergo rapid biological growth and maturation which influences their nutritional requirements. A varied and balanced diet that ensures sufficient energy availability for optimal growth and maturation as well as sporting performance is the cornerstone of youth athlete nutrition and should also allow for youth athletes to meet their micronutrient requirements. In some cases, micronutrient status (e.g., vitamin D and iron) should be monitored and optimized if appropriate by a medical professional. Dietary supplement use is prevalent amongst youth athletes, however is often unnecessary. Education of youth athletes, their parents and coaches on best nutritional practices as well as the risks associated with dietary supplements is vital for their long-term athletic development. Further research in youth winter sports athletes across different stages of growth and maturation competing in a variety of sports is urgently required in order to inform nutritional guidelines for this population

Chambres de cryothérapie et immersion en eau froide : utilisation thérapeutique et risques [Cryotherapy chambers and cold-water immersion : therapeutic use and risks]

Whole body cryotherapy is mainly performed either by immersion in cold water or in a cryotherapy chamber. Practiced since Antiquity and considered as a « natural » method, cryotherapy is attracting more and more followers. Beneficial health effects have been described in the literature. However, interpretation of its effects is difficult due to low quality of current studies. Cryotherapy could however be useful in addition to conventional therapies in various pathologies and situations, provided that the risks, contraindications and rules of good practice are known

Analyse de la variabilité de la fréquence cardiaque : méthodes, limites et exemples cliniques [Heart rate variability: methods, limitations and clinical examples]

Heart rate variability (HRV) is an analysis of milliseconds variations in intervals between heartbeats and has become an increasingly used tool for clinical investigation of fatigue, especially in athletes. Eliciting an indirect index of the autonomic nervous system regulation on the heart rate, HRV correlates with different fatigue states and appears to be a powerful biomarker in their monitoring. This article presents the tools to familiarize with this method while detailing good practices for use and interpretation. A method allowing characterization of different fatigue states is also presented for a clinical use with a systemic approach

Feasibility of a prehabilitation program before major abdominal surgery: a pilot prospective study.

To assess the feasibility of a prehabilitation program and its effects on physical performance and outcomes after major abdominal surgery. In this prospective pilot study, patients underwent prehabilitation involving three training sessions per week for 3 weeks preoperatively. The feasibility of delivering the intervention was assessed based on recruitment and adherence to the program. Its impacts on fitness (oxygen uptake (VO <sub>2</sub> )) and physical performance (Timed Up and Go Test, 6-Minute Walk Test) were evaluated. From May 2017 to January 2020, 980 patients were identified and 44 (4.5%) were invited to participate. The main obstacles to patient recruitment were insufficient time (<3 weeks) prior to scheduled surgery (n = 276, 28%) and screening failure (n = 312, 32%). Of the 44 patients, 24 (55%) declined to participate, and 20 (23%) were included. Of these, six (30%) were not adherent to the program. Among the remaining 14 patients, VO <sub>2</sub> at ventilatory threshold significantly increased from 9.7 to 10.9 mL/min/kg. No significant difference in physical performance was observed before and after prehabilitation. Although prehabilitation seemed to have positive effects on exercise capacity, logistic and patient-related difficulties were encountered. The program is not feasible in its current form for all-comers

Paediatric and adolescent athletes in Switzerland: age-adapted proposals for pre-participation cardiovascular evaluation

High-level sports competition is popular among Swiss youth. Even though preparticipation evaluation for competitive athletes is widespread, screening strategies for diseases responsible for sudden death during sport are highly variable. Hence, we sought to develop age-specific preparticipation cardiovascular evaluation (PPCE) proposals for Swiss paediatric and adolescent athletes (under 18 years of age). We recommend that all athletes practising in a squad with a training load of at least 6 hours per week should undergo PPCE based on medical history and physical examination from the age of 12 years on. Prior to 12 years, individual judgement of athletic performance is required. We suggest the inclusion of a standard 12-lead electrocardiogram (ECG) evaluation for all post-pubertal athletes (or older than 15 years) with analysis in accordance with the International Criteria for ECG Interpretation in Athletes. Echocardiography should not be a first-line screening tool but rather serve for the investigation of abnormalities detected by the above strategies. We recommend regular follow-up examinations, even for those having normal history, physical examination and ECG findings. Athletes with an abnormal history (including family history), physical examination and/or ECG should be further investigated and pathological findings discussed with a paediatric cardiologist. Importantly, the recommendations provided in this document are not intended for use among patients with congenital heart disease who require individualised care according to current guidelines