The metabolic cost of emulated aerodynamic drag forces in marathon running.

The benefits of drafting for elite marathon runners are intuitive, but the quantitative energetic and time savings are still unclear due to the different methods used for converting aerodynamic drag force reductions to gross metabolic power savings. Further, we lack a mechanistic understanding of the relationship between aerodynamic drag forces and ground reaction forces (GRFs) over a range of running velocities. Here, we quantified how small horizontal impeding forces affect gross metabolic power and GRF over a range of velocities in competitive runners. In three sessions, 12 runners completed six 5-min trials with 5 min of recovery in-between. We tested one velocity per session (12, 14, and 16 km/h), at three horizontal impeding force conditions (0, 4, and 8 N) applied at the waist of the runners. On average, gross metabolic power increased by 6.13% per 1% body weight of horizontal impeding force but the increases varied considerably between individuals (4.17%-8.14%). With greater horizontal impeding force, braking GRF impulses decreased, whereas propulsive GRF impulses increased, but the impulses were not related to individual changes in gross metabolic power. Combining our findings with those of previous aerodynamics studies, we estimate that for a solo runner (52 kg) at 2-h marathon pace, overcoming aerodynamic drag force (1.39% BW) comprises 7.8% of their gross metabolic power and drafting can save between 3 min 42 s and 5 min 29 s.NEW & NOTEWORTHY We measured the metabolic and biomechanical effects of small horizontal impeding forces (representing realistic aerodynamic drag forces) on high-caliber runners across a range of velocities. Combining our metabolic results with existing aerodynamic models indicates that at 2-h marathon pace, optimal drafting likely allows a marathoner to run between 3 min 42 s and 5 min 29 s faster. Our rule-of-thumb (∼6% increase in gross metabolic power per 1% body weight of horizontal impeding force) will allow others to estimate the performance enhancement of different drafting formations.

Redacción de historias clínicas como habilidad para el estomatólogo / Writing of medical records as a skill for the dentist

RESUMEN La historia clínica es un documento oficial que exige una redacción rigurosa, pues en ella quedan plasmados datos esenciales del paciente y su padecimiento; así como el tratamiento y las evidencias de su evolución. Debido a lo anterior, es necesario un programa que organice las etapas por las que transita el estudiante para aprender a escribirla. Por ello, el objetivo del presente texto es exponer elementos de un programa que contribuye al desarrollo de habilidades para la redacción de la historia clínica en los estudiantes del tercer año de la carrera Estomatología. Se revisó la literatura científica especializada de cubanos y extranjerosreferida a la temática. Se estudiaron documentos oficiales para conocer los objetivos del modelo del profesional de la carrera Estomatología, así como el programa de la asignatura Propedéutica Clínica y Semiología Estomatológica. Se constataron dificultades en los estudiantes para redactar las historias clínicas y que no existe, al menos en la literatura consultada, un programa que organice las etapas para concretar este proceso. Se propone un programa que brinda orientaciones metodológicas encaminadas a este propósito. El programa permite que los estudiantes sean protagonistas de su proceso de aprendizaje de la redacción de las HC y de su autoevaluación. La investigación constituye una experiencia didáctica puesta en práctica durante el año 2019.

ABSTRACT The clinical history is an official document that requires rigorous drafting, since it contains essential data about the patient and his condition; as well as thetreatment and evidence of his evolution. Due to the above, a program is necessary that organizes the stages the student goes through to learn to write it. Therefore, the objective of this text is to present elements of a program that contributes to the development of skills for the writing of clinical history in students of the third year of the Dentistry career. The specialized scientific literature of Cubans and foreigners on the subject was reviewed. Official documents were studied to know the objectives of the professional model of the Dentistry career, as well as the program of the Clinical Propedeutics and Dentistry Semiology subject. Difficulties were found in the students to write medical records and that there is not, at least in the literature consulted, a program that organizes the stages to specify this process. A program is proposed that provides methodological guidelines for this purpose. The program allows students to be protagonists of their learning process of writing the HC and of theirself-evaluation. There search constitutes a didactic experience put in to practice during the year 2019.

Virtual cycling effort is dependent on power update rate.

Cycling ergometer protocols are commonly integrated with a virtual reality environment (VRE), especially because of its static position that also allows multiple exercise experiments. Concerning VRE scenarios, visually delayed situations like the ones produced at excessive low update rates can also affect the sense of presence and physiological responses. However, the main interface between the subject and a cycling VRE is the power applied over the crank, and there are only a few experiments to evaluate the effect of delayed situations on this particular interface. Thus, this work aims to investigate the effects of the power update rate (PUR) over the subject`s performance on an avatar-based simulator during a drafting task. A custom cycling VRE was built, and 21 male recreational cyclists (175.9 ± 7.5 cm; 76.5 ± 13.9 kg) were tested at six different PUR levels from 100 to 3000 ms. As a result, PUR affects performance scores (virtual distance, efficiency, and heart rate, p < 0.01) at the given VRE conditions. The case-by-case analysis of the groups reveals that higher update rates always lead to a statistical equivalent or superior performance. Nevertheless, no parameter shows any group difference between 500 ms and lower PUR. These results suggest that virtual cycling protocols should consider PUR and other delay-related mechanisms as possible intervening factors over physiological responses and performance scores.

How much further for the sub-2-hour marathon?

The sub-2-hour marathon is a new barrier in endurance running performance, and it has been widely debated in the scientific community. In this review we present a mathematical model to estimate the possible year when a male could break through the sub-2-hour barrier, and also an estimation of when a female could break Paula Radcliffe's marathon running record. Further, we present several aspects (ie, physiology, nationality, age, biomechanics, pacing, and drafting) that are associated with marathon running performance in elite runners and, finally, the possible characteristics of the male to break the sub-2-hour barrier. In summary, with the results of the developed equations, it is possible that a male athlete can break through the sub-2-hour barrier in the next decade (with Nike® Breaking2 performance 1920-2018 [NBP]: y =0.0417x2-14.18x +3,128; year of 2026; without NBP 1920-2018: y =0.045x2-15.12x +3,194; year of 2027). This marathoner will possibly have a maximal oxygen uptake >85 mL∙kg-1∙min-1 and should perform the race at a pacing higher than 85% of maximal oxygen uptake. In addition, this runner should pay more attention to strength training, endurance strength, speed training, and focus on running training at an intensity above the anaerobic threshold. Most likely, this runner originates from East Africa (especially from Ethiopia) and will have an age of ~27 years. For the females, there is poor evidence regarding the physiological profile of the female marathoner who will break Radcliffe's record, but the available literature suggests that it will not happen any time soon.