Novel track field test to determine Vpeak, relationship with treadmill test and 10-km running performance in trained endurance runners.

OBJECTIVES: The aim of this study was to determine the peak running velocity on the track field (Vpeak_TF) based on the laboratory treadmill test (Vpeak_T), and relate the Vpeak values as well as their correlation with the 10-km running performance in trained endurance runners. METHOD: Twenty male trained endurance runners (age: 29.5 ± 5.3 years; V̇O2max: 67.5±17.6 ml · kg-1·min-1) performed three maximum incremental tests to determine the Vpeak: one for Vpeak_T determination and two to obtain Vpeak_TF on the official track field (400 m), and a 10-km running performance. During the incremental tests, maximum heart rate (HRmax), maximal rating of perceived exertion (RPEmax), and peak lactate concentration (LApeak) were determined. RESULTS: The results showed significant difference between the Vpeak_TF and Vpeak_T (18.1 ± 1.2 vs. 19.2 ± 1.5 km·h-1, respectively), as well as the total time of the tests, the distance traveled and the RPEmax determined during the tests. A high correlation was observed between the Vpeak values (r = 0.94), and between Vpeak_TF and Vpeak_T with 10-km running performance (r = -0.95 vs. r = -0.89, respectively). CONCLUSIONS: The good agreement and association with Vpeak_T and high correlation with 10-km running performance demonstrate that the novel track field test is efficient for Vpeak_TF determination.

Curved Approach in High Jump Induces Greater Jumping Height without Greater Joint Kinetic Exertions than Straight Approach.

PURPOSE: The most height-specific jumping mode, the athletic high jump, is characterized as a running single-leg jump (RSLJ) from a curved approach. The main advantage of a curved approach is believed to be facilitation of bar clearance. However, the effect of a curved approach on center-of-mass (CoM) height generation has not been clarified. Here, we show that the curved RSLJ (C-RSLJ) is more suitable than the straight RSLJ (S-RSLJ) for CoM height generation. METHODS: We collected data using motion capture from 13 male high jumpers (personal best, 2.02-2.31 m) that performed C-RSLJ and S-RSLJ. We then compared the energy generation contributing to CoM height (Evert) in each approach. RESULTS: All participants attained greater CoM height in C-RSLJ than in S-RSLJ (difference, 0.055 ± 0.024 m). Three-dimensional joint kinematics and kinetics were similar between both approaches, except for the ankle plantar-flexion torque, which was smaller in C-RSLJ. The sum of positive work was comparable between the approaches, whereas the sum of negative work in C-RSLJ was significantly smaller than in S-RSLJ. The shank forward rotation induced a larger difference in Evert generation between C-RSLJ and S-RSLJ (0.80 ± 0.36 J·kg-1) than any other segment (≤0.36 J·kg-1). CONCLUSIONS: Compared with a straight approach, a curved approach induces greater CoM height without increasing joint kinetic exertions during takeoff. The curved approach changes the initial condition of the takeoff and promotes the transformation of horizontal kinetic energy into Evert. This study provides novel practical perspectives for high jumpers and highlights the importance of segment biomechanics in human motor performance.

Running performance of non-professional female runners from different Brazilian states: the role of environmental characteristics

Abstract Aims: (i) to compare the running performance of non-professional female runners from different Brazilian states; (ii) to estimate the relationship between environmental state-related variables and running performance; and (iii) to analyze the mediation role of training commitment in the relationship between the environment and running performance. Methods: A total of 418 non-professional female runners were sampled from the five Brazilian regions. An online questionnaire was used for data collection and included self-reported information about age, body weight, body height, place of residence, training volume, and running pace. Environmental characteristics were based on the Census 2010 and included percentages of public illumination, asphalt, sidewalks, and green areas for state capital cities. Linear regression, Pearson correlation, and mediation analysis were performed using SPSS 26, at a 95% confidence interval. Results: The fastest women were from the Rio Grande do Sul. Significant differences were observed between Rio Grande do Sul and Rio Grande do Norte (β= 45.79; 95%CI = 16.86 − 74.73), Distrito Federal (β = 34.55; 95%CI = 1.87−67.24), and Sergipe (β = 35.34; 95%CI = 14.09−56.60). A negative relationship was observed between running pace with green areas (r = −0.206; 95%CI = −0.305 − −0.110) and training volume (r = −0.343; 95%CI = −0.427−0.167). Training volume explained 23% of the relationship between the percentage of green areas and running performance. Conclusion: The fastest runners were from the Rio Grande do Sul. Higher percentages of green areas can favor performance, which is partly mediated by increased training volume.

Training Load, Heart Rate Variability, Direct Current Potential and Elite Long Jump Performance Prior and during the 2016 Olympic Games.

The primary objective of this investigation was to investigate the relationships between training load (TL), heart rate variability (HRV) and direct current potential (DC) with elite long jump performance prior to and during the 2016 Olympics Games. Sessional ratings of perceived exertion (sRPE), training duration, HRV and DC were collected from four elite athletes (26.4 ± 1.4 years, height 1.83 ± 0.05 m, weight 68.9 ± 5.0 kg) for a 16-week period in qualification for and competition at the 2016 Olympic Games. Acute and chronic TL, training stress balance and differential load were calculated with three different smoothing methods. These TL measures along with HRV and DC were examined for their relationship to intra-athlete performance using repeated measure correlations and linear mixed models. Successful compared to unsuccessful intra-athlete performances were characterised by a higher chronic TL (p < 0.01, f2 = 0.31) but only when TL was exponentially smoothed. There were also negative correlations between HRV and performance (r = -0.55, p < 0.01) and HRV was significantly lower for more successful performances (p < 0.01, f2 = 0.19). Exponentially smoothed chronic TL was significantly higher and HRV was significantly lower for successful intra-athlete performances prior and during the 2016 Olympics Games in an elite group of long jump athletes. Monitoring sRPE and HRV measures and manipulating TL prior to competition seems worthwhile for elite long jump athletes.

Surmising synchrony of sound and sight: Factors explaining variance of audiovisual integration in hurdling, tap dancing and drumming.

Auditory and visual percepts are integrated even when they are not perfectly temporally aligned with each other, especially when the visual signal precedes the auditory signal. This window of temporal integration for asynchronous audiovisual stimuli is relatively well examined in the case of speech, while other natural action-induced sounds have been widely neglected. Here, we studied the detection of audiovisual asynchrony in three different whole-body actions with natural action-induced sounds-hurdling, tap dancing and drumming. In Study 1, we examined whether audiovisual asynchrony detection, assessed by a simultaneity judgment task, differs as a function of sound production intentionality. Based on previous findings, we expected that auditory and visual signals should be integrated over a wider temporal window for actions creating sounds intentionally (tap dancing), compared to actions creating sounds incidentally (hurdling). While percentages of perceived synchrony differed in the expected way, we identified two further factors, namely high event density and low rhythmicity, to induce higher synchrony ratings as well. Therefore, we systematically varied event density and rhythmicity in Study 2, this time using drumming stimuli to exert full control over these variables, and the same simultaneity judgment tasks. Results suggest that high event density leads to a bias to integrate rather than segregate auditory and visual signals, even at relatively large asynchronies. Rhythmicity had a similar, albeit weaker effect, when event density was low. Our findings demonstrate that shorter asynchronies and visual-first asynchronies lead to higher synchrony ratings of whole-body action, pointing to clear parallels with audiovisual integration in speech perception. Overconfidence in the naturally expected, that is, synchrony of sound and sight, was stronger for intentional (vs. incidental) sound production and for movements with high (vs. low) rhythmicity, presumably because both encourage predictive processes. In contrast, high event density appears to increase synchronicity judgments simply because it makes the detection of audiovisual asynchrony more difficult. More studies using real-life audiovisual stimuli with varying event densities and rhythmicities are needed to fully uncover the general mechanisms of audiovisual integration.

The strategy of physiological arousal of athletes in sports competition based on drug intervention / A estratégia da excitação fisiológica de atletas em competições esportivas com base em intervenção medicamentosa / Deportistas basados en intervenciones farmacéuticas, estrategia fisiológica de despertar

ABSTRACT Generally speaking, the physiological index of the human body is in a relatively stable state, which refers to the function of various organ systems with the characteristics of high-tide period, low-tide period and critical period. However, for competitive athletes, it is necessary to maintain physiological activation in both training and competition. In view of this, this study will analyze the physiological arousal degree of aspirin and acetaminophen in order to provide a reference for athletes to take analgesic drugs. In this study, the analytic hierarchy process (AHP), principal component analysis and factor analysis, were used to construct a scientific evaluation system of physiological arousal level, and the medication and non-medication status of 90 athletes were evaluated. The results showed that aspirin was better than acetaminophen in blood urea and serum creatine kinase, and the comprehensive score of some athletes was higher than 0.95. Aspirin is better in arousing athletes' physiology. The research results will provide scientific guidance for athletes to take antipyretic and analgesic drugs.

RESUMO Em termos gerais, o índice fisiológico do corpo humano encontra-se num estado relativamente estável, que se refere à função de vários sistemas de órgãos no corpo humano, com as características do período de altas, período de baixas e período crítico. No entanto, para atletas competitivos, é necessário manter a ativação fisiológica em treinamento e competição. Em vista disso, este estudo irá analisar o grau fisiológico de excitação de aspirina e acetaminofeno, a fim de fornecer referência para os atletas a tomar medicamentos analgésicos. Neste estudo, o Analytic Hierarchy Process (AHP), análise de componentes principal e análise de fatores foram usados para construir um sistema de avaliação científica de nível de excitação fisiológica, e o estado de medicação e de não medicação de 90 atletas foram avaliados. Os resultados mostraram que a aspirina foi melhor do que o acetaminofeno na ureia sanguínea e na creatina quinase sérica, e o escore abrangente de alguns atletas foi maior do que 0.95. A aspirina é melhor no despertar da fisiologia dos atletas. Os resultados da pesquisa fornecerão orientação científica para os atletas tomarem medicamentos antipiréticos e analgésicos.

RESUMEN En términos generales, el índice fisiológico del cuerpo humano se encuentra en un estado relativamente estable, que se refiere a la función de varios sistemas de órganos en el cuerpo humano, con las características del período de altas, período de bajas y período crítico. Mientras tanto, para atletas competitivos, es necesario mantener la activación fisiológica en entrenamiento y competición. En vista de eso, este estudio analizará el grado fisiológico de excitación de aspirina y acetaminofeno, a fin de proveer referencia para los atletas para tomar medicamentos analgésicos. En este estudio, el Analytic Hierarchy Process (AHP), análisis de componentes principal y análisis de fatores fueron usados para construir un sistema de evaluación científica de nivel de excitación fisiológica, y el estado de medicación y de no medicación de 90 atletas fueron evaluados. Los resultados mostraron que la aspirina fue mejor que el acetaminofeno en la urea sanguínea y en la creatina quinasa sérica, y el escore abarcador de algunos atletas fue mayor de 0.95. La aspirina es mejor en el despertar de la fisiología de los atletas. Los resultados de la investigación proveerán orientación científica para que los atletas tomen medicamentos antipiréticos y analgésicos.

Traditional high jump Gusimbuka Urukiramende: Could early 20th century African athletes beat Olympic champions?

During the first half of the 20th century, extraordinary high jumping performances of East-African athletes were observed. These athletes used a specific native jumping style called Gusimbuka Urukiramende. Eye-witnesses believed that these performances could have been world-records and that these athletes could have competed at the Olympics. However, these athletes never participated in international competitions and there is no other proof to support these performance claims. We have analysed historical photos and cine sequences of these jumps, documented the movement analysis of this technique, quantified performance and compared it to contemporaneous elite performances. Our analyses demonstrate that Gusimbuka Urukiramende athletes did not jump as high as the world record. Nevertheless, even though they used a suboptimal jump technique (because they had to lift their bodies higher to cross the bar) they could cross bar heights of 188 cm or 106% body height and as such their performance still was worthy of participation to the Olympics.

Critical Speed throughout Aging: Insight into the World Masters Championships.

PURPOSE: This study aimed to determine how the speed-distance relationship, described by critical speed (CS) and distance prime (D'), is altered with aging. METHODS: Official race data from the past eight World Masters Athletics Indoor Track and Field World Championships were used for this study. CS and D' were calculated for female and male athletes (35-90 yr of age) who registered times for the 800-, 1500-, and 3000-m runs during a single championship to determine the relationship between age and CS and D'. Twenty-six athletes completed sufficient races in multiple championships to retrospectively assess the change in CS and D' over time. RESULTS: Cross-sectional data indicated that CS continuously decreases after age 35 yr in a curvilinear manner with advancing age (R2 = 0.73, P < 0.001, n = 187), with even greater decreases in CS occurring after ~70 yr of age. D' also changed in a curvilinear manner with age (R2 = 0.45, P < 0.001, n = 103), such that decreases were observed between 35 and 70 yr, followed by an increase in D' thereafter. Retrospective, longitudinal data, with an average follow-up of 6.38 ± 1.73 yr, support these findings, indicating that the annual decrease in CS grows with advancing age (e.g., ~1% vs ~3% annual decrease in CS at age 55 vs 80 yr, respectively) and that D' shifts from an annual decrease (e.g., ~2.5% annual decrease at 55 yr) to an annual increase (e.g., ~2.5% annual increase at 80 yr) around 70 yr of age. Importantly, the relationship between CS and race pace was unaffected by age, supporting the relevance of CS throughout aging. CONCLUSION: Even among world-class athletes, CS decreases and D' changes with aging. These adaptations may contribute to the diminished exercise ability associated with aging.

Longitudinal Master Track and Field Performance Decline Rates Are Lower and Performance Is Better Compared to Athletes Competing Only Once.

In master athletics research, cross-sectional data are easier to obtain than longitudinal data. While cross-sectional data give the age-related performance decline for a population, longitudinal data show individual trajectories. It is not known whether athletes who repeatedly compete have (a) a better performance and (b) a slower age-related decline in performance than that obtained from cross-sectional data from athletes competing only once. To investigate this, we analyzed 33 254 results of 14 118 male athletes from 8 disciplines in the database of "Swedish Veteran Athletics." For each discipline and for the pooled data of all disciplines, quadratic models of the evolution of performance over time were analyzed by ANCOVA/ANOCOVA using MATLAB. The performance was higher in athletes with 2 or more data points compared to those with only n = 1 (p < .001), with further increases in performance with an increasing number of data points per athlete. The estimated performance decline was lower in people with 2 or more results (sprint, 10 km, jumps; p < .001). In conclusion, we showed that longitudinal data are associated with higher performance and lower performance decline rates.

Prediction of throwing distance in the men's and women's javelin final at the 2017 IAAF world championships.

The purpose of this study was to use regularised regression models to identify the most important biomechanical predictors of throwing distance in elite male (M) and female (F) javelin throwers at the 2017 IAAF world championships. Biomechanical data from 13 male and 12 female javelin throwers who competed at the 2017 IAAF world championships were obtained from an official scientific IAAF report. Regularised regression models were used to investigate the associations between throwing distance and release parameters, whole-body kinematic and joint-level kinematic data. The regularised regression models identified two biomechanical predictors of throwing distances in both M and F javelin throwers: release velocity and knee flexion angle of the support leg at the moment of javelin release. In addition, the length of the delivery stride was an important predictor of throwing distance in M throwers, whereas the javelin's attitude angle and the distance between the whole-body centre of mass and the centre of mass of the back foot at the beginning of the delivery phase were important predictors of throwing distance in F throwers.

Changes in performances/characteristics of French female runners over the last 12 years.

This study investigated the changes in performance of five official track running distances (800m, 1500m, 3000m, 5000m and 10,000m) and the characteristics of French female runners between 2005 and 2016. 22,839 official track performances were scrutinized. For each performance, the race time, the indication of personal record, age, and performance level were recorded. The main results showed that: (1) the number of French track performances has increased in recent years (except for the 10,000m) and the level of these performances has improved significantly only for the longer distances (5000 and 10,000m), (2) the longest distances were generally performed by older athletes, and (3) the highest percentage of international athletes was for the 10,000m event. These findings may be explained by: (1) the development plan put into place by the Fédération France d'Athlétisme, (2) age-dependent physiological and psychological factors and environmental conditions, and (3) the minima to access the international level.

Temporal Trends in the Standing Broad Jump Performance of United States Children and Adolescents.

Purpose: To estimate temporal trends in broad jump performance for United States youth, a marker of muscular fitness and health. Method: Electronic databases, topical systematic reviews, and personal libraries were systematically searched for studies reporting descriptive standing broad jump data for apparently healthy United States youth (age 10-17 years). Temporal trends at the sex-age level were estimated using sample-weighted regression models associating the year of testing to mean jump performance, with national trends standardized to the year 1985 using a post-stratified population-weighting procedure. Results: Collectively, there was a small increase of 12.6 cm (95%CI: 12.5 to 12.7) or 7.9% (95%CI: 7.1 to 8.6) in 65,527 United States youth between 1911 and 1990. Increases were greater for girls (change in means [95% CI]: 17.1 cm [16.9 to 17.3]; 11.4% [10.7 to 12.2]) compared to boys (change in means [95% CI]: 8.5 cm [8.3 to 8.7]; 4.6% [3.8 to 5.4]), but did not differ between children (10-12 years) and adolescents (13-17 years). Increases in broad jump performance were not always uniform across time, with steady and progressive increases observed for boys and children, respectively, and a diminishing rate of increase observed for girls and adolescents. Conclusions: Muscular fitness is a good marker of health, so greater broad jump performance from 1911 to 1990 may reflect corresponding changes in health. Routine assessment of broad jump performance may be useful to monitor trends in health and muscular fitness of United States youth due to its practicality, scalability, and predictive utility.

Comparison of force-velocity profiles of the leg-extensors for elite athletes in the throwing events relating to gender, age and event.

Strength capabilities of the leg-extending muscles play an important role in athletic throwing events, where a high momentum must be transferred to the throwing device. The objective of this study was to quantify the force-velocity profiles of the leg-extending muscles considering gender, age and event. The leg-extending forces of 143 elite-athletes (59 females, 84 males) of the athletic throwing events were measured during isokinetic leg press tasks at four speeds. The maxima of force, power and contraction velocity of a knee-extending model muscle could be determined by means of a scalable geometric model and linear fitting. This method makes different groups of athletes comparable. Furthermore, the individually achieved release speeds were measured in a field test. Female and male throwers showed a different development of force-velocity profiles during their maturation process. For the men the development is more speed-oriented. We identified shot putters and javelin throwers to be the athletes with the highest leg-extending power. The importance of leg-extending muscle strength for the complex field performance for the throwing events was confirmed. The presented approach allows to give support in controlling and guiding of leg-extension strength training for both different stages of maturing and varying throwing events.

Optimal mass of the arm segments in throwing: A two-dimensional computer simulation study.

Producing a high release speed is important in throwing sports such as baseball and the javelin throw. Athletes in throwing sports might be able to achieve a greater throwing speed by improving the effectiveness of the kinetic chain. In this study a two-dimensional computer simulation model of overarm throwing was used to examine the effect of changes in forearm mass and upper arm mass on the release speed of a lightweight (58 g) projectile. The simulations showed that increasing the mass of the forearm decreases release speed, whereas increasing the mass of the upper arm initially increases release speed. For a given forearm mass there is an optimal upper arm mass that produces the greatest release speed. However, the optimal upper arm mass (5-6 kg) is substantially greater than that of an average adult (2.1 kg). These results suggest that athletes might be able to throw faster if they had a stronger tapering of segment mass along the length of their arm. A stronger taper could be readily achieved by attaching weights to the upper arm or by using hypertrophy training to increase the mass of the upper arm. High-speed overarm throwing is a complex three-dimensional movement and this study was a preliminary investigation into the effect of arm segment mass on throwing performance. Further simulation studies using three-dimensional throwing models are needed to generate more accurate insights, and the predictions of the simulation studies should be compared to data from experimental intervention studies of throwing sports.

Impact of the talent development environment on the wellbeing and burnout of Caribbean youth track and field athletes.

This study examined the perceived talent development environment (TDE) of youth track and field athletes within the Caribbean region and explores the relationship with their subjective wellbeing and burnout levels. A sample of 400 Caribbean youth track and field athletes (male = 198, and female = 202; age 13-20 years) participated in this cross-sectional study. Athletes responded to a survey which included the Talent Development Environment Questionnaire (TDEQ-5), the World Health Organization Wellbeing Index (WHO-5) and the Athlete Burnout Questionnaire (ABQ). Structural equation modelling showed that a positive and supportive TDE was associated with better athlete wellbeing and lower athlete burnout. Moreover, gender and hours of training moderated relationships of athletes' perceptions of their development environment with wellbeing and burnout levels respectively. Furthermore, there was a positive association between the support network and athlete wellbeing, while holistic quality preparation was negatively associated with athlete burnout. Development environments perceived as supportive and geared towards a holistic athlete-centred approach were associated with better athlete wellbeing and lower burnout.

Performance progression of elite jumpers: Early performances do not predict later success.

This study aimed (a) to estimate the transition rate for top 50 ranked track and field jumpers, (b) to compare the performance progression of top 50 ranked senior jumpers (top50 senior) to those who failed to be top 50 ranked in the senior category despite being top 50 ranked in the under 18 category (only U18), and (c) to verify whether relative age effect may at least partially explain the differences in the two above-mentioned subgroups. The career performance trajectories of 5981 athletes (2837 females) competing in jump events from 2000 to 2019 were extracted from the World Athletics database. The all-time top 50 ranked athletes for each age from 16 years to senior category were identified. Performance progression characteristics were compared using linear mixed-effects model. Only 8% of males and 16% of females top 50 ranked at the age of 16 years managed to be included among the top50 senior. Only U18subgroup made the first appearance in the database (at 15-16 years) and reached the peak performance (at 20 years) earlier than top50 senior (17-18 and 26-27 years, respectively). The relative age effect was largely present in Only U18 but not in top50 senior subgroups. Most of the early-successful U18 world-class jumpers did not manage to maintain the same level of competitiveness in adulthood since they experienced a plateau in performance from 20 years of age. Conversely, top 50 ranked senior jumpers continued to produce consistent performance improvement up to 26-27 years of age.

Non-linear association of efficiency of practice of adult elite athletes with their youth multi-sport practice.

We explored associations of elite athletes' multi-year efficiency of practice and improvement of performance with their current and earlier participation patterns. Participants were 80 adult German track-and-field national-squad athletes. Performance improvement was measured as development of athletes' highest track-and-field championship level and placing from 19 to 25 years (t1-t2). Practice efficiency was defined as performance improvement per amount of coach-led athletics practice from t1 to t2. Participation variables included amounts of coach-led practice and peer-led play in athletics and other sports through t1 and t1-t2. Analyses involved an advanced machine learning procedure, XGBoost, allowing non-linear, multivariate exploration. We computed two models, one for performance improvement ("good" discriminative performance, AUC = 0.82) and one for practice efficiency ("fair", AUC = 0.73). Four central findings emerged: 1. Childhood/adolescent coach-led multi-sport practice was a critical discriminator of adult practice efficiency and performance improvement. 2. Associations were non-linear, displaying a saturation pattern. 3. The likelihood of achieving high adult practice efficiency was greatest when combining ~1,000-2,500 track-and-field practice hours until t1 with ~1,250 other-sports practice hours until t1. 4. Peer-led engagement in any sport had negligible effects. Childhood/adolescent multi-sport coach-led practice apparently facilitated long-term sustainability of athletes' development of adult practice efficiency and performance improvement in athletics.

Lower Extremity Kinematic and Kinetic Asymmetries during Running.

PURPOSE: The primary aims of this investigation were to describe the magnitude of asymmetries of common variables during running among healthy athletes and to determine if sex and speed influence magnitudes of asymmetry. METHODS: This study analyzed routinely collected running gait data on healthy Division I collegiate athletes. All athletes had no history of lower extremity surgery, no lower extremity injuries for 3 months before testing, and running data available at 2.68, 2.95, 3.35, 3.80, and 4.47 m·s-1. Asymmetries were calculated for ground reaction forces, spatiotemporal metrics, joint kinematics, and joint kinetics. Separate linear mixed-effects models assessed the influence of sex, speed, and the interaction on asymmetries of interest. z Scores were calculated for significant effects to further assess the magnitude of differences. RESULTS: Results from 204 athletes were included. The magnitude of asymmetry varied depending on the variable of interest, with asymmetries ≤3° observed for joint kinematics and greater asymmetries observed among joint work asymmetries ranging from 10% to 40%. No significant interactions between sex and speed were observed. Differences in sex and speed were noted; however, the effect sizes were very small based on z score comparison (-0.17 ≤ z ≤ 0.36) and were unlikely to be meaningful. CONCLUSIONS: The magnitude of asymmetry varies considerably depending on the running gait variable. Interpretation of between-limb asymmetry in running mechanics needs to be specific to the variable of interest, whereas sex or running speed seem to be minor factors.

El peroné: mal alumno, pero buen profesor. (¿Qué tiene prioridad biológica: la integridad, o la supervivencia?) / Fibula: a bad pupil but a good profesor. (What comes first, integrity or survival?)

La concepción original del mecanostato como un regulador de la rigidez estructural ósea orientado a mantener un determinado 'factor de seguridad' en todos los esqueletos parece no corresponder por igual a cualquier hueso y para cualquier tipo de estímulo. Hemos descubierto que la estructura cortical diafisaria del peroné humano manifiesta un comportamiento ambiguo del sistema, referido al uso del pie. La diáfisis peronea, además de ser insensible al desuso, se rigidiza, como sería de esperar, por entrenamientos en disciplinas deportivas que rotan o revierten el pie (hockey, fútbol, rugby); pero, llamativamente, se flexibiliza en su mitad proximal por entrenamiento en carrera larga, que optimiza el rendimiento del salto que acompaña a cada paso. La referida rigidización robustecería la región peronea de inserción de los músculos que rotan o revierten el pie, favoreciendo la locomoción sobre terrenos irregulares o 'gambeteando', propia de especies predadoras como los leopardos. La 'inesperada' flexibilización proximal, pese a reducir la resistencia a la fractura por flexión lateral (poco frecuente en el hombre), favorecería la absorción elástica de la energía contráctil de la musculatura inserta, optimizando el rendimiento del salto al correr, condición vital para especies presas como las gacelas. La falta de analogía de estas respuestas de la estructura peronea a distintos entrenamientos, incompatible con el mantenimiento de un factor de seguridad, sugiere su vinculación preferencial con la optimización de aptitudes esqueléticas con valor selectivo. Esto ampliaría el espectro regulatorio del mecanostato a propiedades esqueléticas 'vitales', más allá del control de la integridad ósea. Su manifestación en el hombre, ajena a connotaciones selectivas (quizá resultante del mantenimiento de genes ancestrales), permitiría proponer la indicación de ejercicios orientados en direcciones preferenciales a este respecto, especialmente cuando estas coincidieran con las de las fuerzas que podrían fracturar al hueso. (AU)

The original notion of the mechanostat as a regulator of bone structural rigidity oriented to maintain a certain 'safety factor' in all skeletons does not seem to correspond equally to every bone and for any type of stimulus. We have discovered that the diaphyseal cortical structure of the human fibula shows an ambiguous behavior of the system, with reference to the use of the foot. The peroneal shaft, in addition to being insensitive to disuse, becomes stiffened, as might be expected, by training in sport disciplines that involve rotating or reversing the foot (hockey, soccer, rugby); but, remarkably, it becomes more flexible in its proximal half by long-distance running training, which optimizes the performance of the jump that accompanies each step. The stiffening would strengthen the peroneal region of insertion of the muscles that rotate or reverse the foot, favoring locomotion on uneven terrain or 'dribbling', typical of predatory species such as leopards. The 'unexpected' proximal flexibilization, despite reducing the resistance to lateral flexion fracture (rare in human), would favor the elastic absorption of contractile energy from the inserted muscles, optimizing jumping performance when running, a vital condition for prey species such as gazelles. The lack of analogy of these responses of the peroneal structure to different training, incompatible with the maintenance of a safety factor, suggests its preferential link with the optimization of skeletal aptitudes with selective value. This would expand the regulatory spectrum of the mechanostat to 'vital' skeletal properties, beyond the control of bone integrity. Its manifestation in humans, oblivious to selective connotations (perhaps resulting from the maintenance of ancestral genes), would make it possible to propose the indication of exercises oriented in preferential directions, especially when they coincide with the direction of the forces that could fracture the bone. (AU)