A preliminary investigation of the use of inertial sensing technology for the measurement of hip rotation asymmetry in horse riders

This study investigated the use of inertial sensing technology as an indicator of asymmetry in horse riders, evidenced by discrepancies in the angle of external rotation of the hip joint. Twelve horse and rider combinations were assessed with the rider wearing the XsensTM MVN inertial motion capture suit. Asymmetry (left vs right) was revealed in mean hip external rotation of all riders, with values ranging from 1° to 27°, and 83% showed greater external rotation of the right hip. This study represents novel use of inertial sensing equipment in its application to the measurement of rider motion patterns. The technique is non-invasive, is capable of recording rider hip rotation asymmetry whilst performing a range of movements unhindered and was found to be efficient and practical, with potential to further advance the analysis of horse and rider interactions

Association of low back pain on physical, sociodemographic and lifestyle factors across a general population sample within Greece

All rights reserved. BACKGROUND: Although low back pain (LBP) is a debilitating problem internationally, there is not a lot of research on its impact on physical, psychosocial and lifestyle factors. Especially in mediterranean countries, such as Greece, it is not sufficiently explored whether physical (pain location, activity limitation etc.), sociodemographic (education, smoking etc.) or lifestyle factors (i.e. quality of life or anxiety) are influenced by LBP. OBJECTIVE: To estimate LBP prevalence in the Greek general population and explore its association with particular sociodemographic, physical and lifestyle factors. METHOD: A sample of 3125 people of the Greek adult population was randomly selected by stratified sampling encompassing rural and urban representation within the Greek mainland. An extended survey form was developed entailing three sections; personal (sociodemographic) information, questions on symptomatology and physical factors (i.e. pain characteristics, recurrence, physical disability etc.) and 3 self-administered questionnaires (including mostly lifestyle factors); Hospital Anxiety and Depression (HAD) scale for anxiety and depression, SF-12 for quality of life (QoL) and Roland-Morris for disability. RESULTS: A total of 471 (15%) people reported LBP (210 males, mean age: 47.04 ' 15.03). Amongst them 60% reported sciatica, 76% suffered recurrent LBP and 70% received specialist care. Low disability levels, moderate to high pain intensity, gender differences and good self-reported QoL and psychosocial status were reported. Sociodemographic characteristics (income, smoking, marital status etc.) were not associated with LBP physical factors, apart from age which correlated with physical disability and wellness (r being 0.446 and 0.405, respectively, p < 0.001). Physical factors (particularly pain intensity and location) correlated with lifestyle factors (QoL) and disability (r ranging between 0.396 and 0.543, p < 0.001). Mental wellness, anxiety and depression (as lifestyle factors) were not associated with sociodemographic or physical factors. CONCLUSIONS: Physical parameters were amongst the most prevalent characteristics of the Greek sample, thus offering a direction towards a more targeted treatment and rehabilitation planning. Unlike previous literature, most sociodemographic characteristics were not correlated with any LBP physical or lifestyle factors, thus possibly indicating a different socioeconomic background and aetiology domain to that of the usual non-specific LBP spectrum

Isokinetic evaluation of knee muscles in soccer players: discriminant analysis [Avaliação isocinética dos músculos do joelho em jogadores de futebol: análise discriminante]; [Evaluación isocinética de los músculos de la rodilla en jugadores de fútbol: análisis discriminante]

Introduction: Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance. Objectives: To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17) soccer category from the professional (PRO). Methods: Thirty four players were assessed (n=17 for each category). The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm), total work (J), average power (W), angle of peak torque (deg.), agonist/ antagonist ratio (%), measured for three velocities (60°/s, 120°/s and 300°/s), with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories. Results: The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work. Conclusion: Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players. RESUMO Introdução: A atividade muscular em jogadores de futebol pode ser medida por meio do dinamômetro isocinético, que é um instrumento confiável para avaliação do desempenho humano. Objetivos: Conduzir análises isocinéticas e discriminar quais variáveis diferenciam a categoria sub-17 (S17) da profissional (PRO). Métodos: Trinta e quatro jogadores de futebol (n=17 para cada categoria) foram avaliados. As variáveis isocinéticas utilizadas para a análise de extensão-flexão do joelho foram: pico de torque (Nm), trabalho total (J), potência média (W), ângulo de pico de torque (graus), razão agonista/antagonista (%), testadas em três velocidades (60°/s, 120°/s e 300°/s), com cada série contendo cinco repetições. Três análises discriminantes foram feitas usando o método Wilk's Lambda para identificar quais variáveis fariam uma discriminação significativa entre as duas categorias. Resultados: As variáveis discriminantes a 60°/s na categoria PRO foram: pico de torque extensores, trabalho total flexores, potência média de extensores e razão agonista/antagonista; e para os S17 foram: trabalho total de extensores, pico de torque de flexores e potência média de flexores. A 120°/s para a categoria PRO as variáveis discriminantes foram: pico de torque de flexores e potência média de extensores; para os S17 foram: trabalho total de extensores e potência média de flexores. A 300°/s, as variáveis encontradas para as categorias PRO e S17 foram, respectivamente: potência média de extensores e trabalho total de extensores. Conclusão: As variáveis isocinéticas para os músculos do joelho flexores e extensores foram capazes de fazer uma discriminação significativa entre jogadores de futebol PRO e S17. RESUMEN Introducción: La actividad muscular en jugadores de fútbol puede ser medida por medio del dinamómetro isocinético, que es un instrumento confiable para evaluación del desempeño humano. Objetivos: Conducir análisis isocinéticos y discriminar qué variables diferencian la categoría sub-17 (S17) de la profesional (PRO). Métodos: Fueron evaluados treinta y cuatro jugadores de fútbol (n=17 para cada categoría). Las variables isocinéticas utilizadas para el análisis de extensión-flexión de la rodilla fueron: pico de torque (Nm), trabajo total (J), potencia media (W), ángulo de pico de torque (grados), razón agonista/antagonista (%), probadas en tres velocidades (60°/s, 120°/s y 300°/s), con cada serie conteniendo cinco repeticiones. Fueron realizados tres análisis discriminantes usando el método Wilk's Lambda para identificar qué variables harían una discriminación significativa entre las dos categorías. Resultados: Las variables discriminantes a 60°/s en la categoría PRO fueron: pico de torque extensores, trabajo total flexores, potencia media de extensores y razón agonista/antagonista; y para los S17 fueron: trabajo total de extensores, pico de torque de flexores y potencia media de flexores. A 120°/s para la categoría PRO las variables discriminantes fueron: pico de torque de flexores y potencia media de extensores; para los S17 fueron: trabajo total de extensores y potencia media de flexores. A 300°/s, las variables encontradas para las categorías PRO y S17 fueron, respectivamente: potencia media de extensores y trabajo total de extensores. Conclusión: Las variables isocinéticas para los músculos de la rodilla flexores y extensores fueron capaces de hacer una discriminación significativa entre jugadores de fútbol PRO y S17

Recovery kinetics of knee flexor and extensor strength after a football match

© 2015 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0128072We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12h (both limbs) and 36h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36h at 60°/s and for 60h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level.Published versio

Output Substitution in Multi-Species Trawl Fisheries: Implications for Quota Setting

In most multi-species fisheries managed through output controls, total allowable catches (TACs) are set primarily on the basis of biological considerations, usually on a species by species basis. An implicit assumption of management is that fishers are able to adjust their product mix in line with these quotas. If this is not the case, then over-quota catch occurs, leading to either illegal landings or discards. In either case, the effectiveness of the TAC in conserving the resource is reduced. In this paper we show that in the case of multi-species fisheries that exhibit jointness in production, setting TACs on an individual species' basis is inappropriate. In particular, we quantify technical interactions through the estimation of a multi-output distance function for the UK North Sea beam and otter trawl fisheries, and find that in most cases, the potential of substitutability between the main and alternative species is relatively small. We argue that failure to quantify and integrate these technical interactions in the construction of management instruments for fisheries regulation, may result in increased discarding, illegal fishing and potentially lower than expected future yields

Acute effects of static self-stretching exercises and foam roller self-massaging on the trunk range of motions and strength of the trunk extensors

Although the effectiveness of static self-stretching exercises (SSSEs) and foam roller self-massaging (FRSM) in joint range of motion and muscle strength of the lower limbs has been exten-sively investigated, little is known about their effectiveness on the posterior trunk muscles. The present study aimed to investigate the acute effects of two 7-min SSSEs and FRSM intervention protocols on the range of trunk movements and the strength of the trunk extensors. Twenty-five healthy active males (n = 14) and females (n = 11) performed each intervention separately, one week apart. The range of motion (ROM) of the trunk-hip flexion (T-HF), the ROM of the trunk side-flexion (TSF) and rotation (TR) bilaterally, as well as the isometric maximum strength (TESmax) and endurance (TESend) of the trunk extensors were measured before and after each intervention. The ROMs of T-HF, TSF, and TR were significantly increased following both SSSEs and FRSM. The TESmax and TESend were also significantly increased after FRSM, but decreased following SSSEs. While both interventions were effective in increasing the range of motion of the trunk, a single 7-min session of FRSM presented more advantages over a similar duration SSSEs protocol due to the increase in the strength of the trunk extensors it induced. © 2021 by the authors. Licensee MDPI, Basel, Switzerland