Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females

Aim: To investigate whether there is a sex difference in exercise induced muscle damage. Materials and Method: Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20–90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage. Results: Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (p0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (p<0.05), and remained higher when maximal voluntary eccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (p<0.05). Conclusion: Based on isometric torque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage

Muscle strength control in women: Oestrogen, ACE and training effects.

The thesis describes the result of measuring force during voluntary contractions of the hand muscles, during stretch and in response to single magnetic stimuli. Measurements were made of muscle size and of handgrip strength in functional tasks. Groups of subjects studied included men, pre-menopausal women, post-menopausal women using HRT and those not using HRT. A follow up study was made of subjects from a previously published trial of HRT and observations were made of their ACE (angiotensin converting enzyme) genotypes. The in vivo effects of stretch velocity and activation level on the ratio of the force during stretch to that during isometric contraction (E/I) were investigated. All the female groups were studied before and after training of one hand. The benefits to muscle strength of HRT lasted several years even in those who stopped treatment after 1-2 years. The benefits of HRT were greater in those having one or more copies of the I form of the ACE gene compared to those homozygous for the D form. A stretch velocity >435 mm/sec is required for E/I to be independent of velocity. E/I is dependent on the isometric force (I) at the time of stretch and as activation level increases E/I decreases exponentially. Muscle strength of the trained hand, but not of the control hand, improved with training in all groups. The response to training was significantly greater in the postmenopausal women not taking HRT, compared to the other groups. Muscle strengthening occurred without significant size changes. There were no significant changes in the size of the interpolated twitches. The increase in strength caused by training was accompanied by a decrease in E/I following a relationship to I similar to that described for the changes in voluntary force development. There were marked improvements in hand function after training; these were likely due to a learning effect, since both trained and untrained hands showed similar effects. The implications of these findings are discussed

The human patellar tendon moment arm assessed in vivo using dual-energy X-ray absorptiometry

Accurate assessment of muscle-tendon forces in vivo requires knowledge of the muscle-tendon moment arm. Dual-energy X-ray absorptiometry (DXA) can produce 2D images suitable for visualising both tendon and bone, thereby potentially allowing the moment arm to be measured but there is currently no validated DXA method for this purpose. The aims of this study were (i) to compare in vivo measurements of the patellar tendon moment arm (d) assessed from 2D DXA and magnetic resonance (MR) images and (ii) to compare the reliability of the two methods. Twelve healthy adults (mean±SD: 31.4±9.5yr; 174.0±9.5cm; 76.2±16.6kg) underwent two DXA and two MR scans of the fully extended knee at rest. The tibiofemoral contact point (TFCP) was used as the centre of joint rotation in both techniques, and the d was defined as the perpendicular distance from the patellar tendon axis to the TFCP. The d was consistently longer when assessed via DXA compared to MRI (+3.79±1.25mm or +9.78±3.31%; P<0.001). The test-retest reliability of the DXA [CV=2.13%; ICC=0.94; ratio limits of agreement (RLA)=1.01 (*/÷1.07)] and MR [(CV=2.27%; ICC=0.96; RLA=1.00 (*/÷1.07)] methods was very high and comparable between techniques. Moreover, the RLA between the mean DXA and MRI d values [1.097 (*/÷1.061)] demonstrated very strong agreement between the two methods. In conclusion, highly reproducible d measurements can be determined from DXA imaging with the knee fully extended at rest. This has implications for the calculation of patellar tendon forces in vivo where MR equipment is not available. © 2014 Elsevier Ltd

Prevalence and orthopedic management of foot and ankle deformities in Charcot Marie Tooth disease

Introduction/Aims: We aimed to determine whether specific severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) vaccines may be associated with acute-onset polyradiculoneuropathy and if they may result in particular clinical presentations. Methods: We retrospectively reviewed records of all persons presenting with acute-onset polyradiculoneuropathy from January 1, 2021, to June 30, 2021, admitted to two Neuroscience centers, of the West and North Midlands, United Kingdom. We compared subjects with previous SARS-CoV2 vaccine exposure with a local cohort of persons with acute-onset polyradiculoneuropathy admitted between 2005 and 2019 and compared admission numbers for the studied time frame with that of the previous 3 years. Results: Of 24 persons with acute-onset polyradiculoneuropathy, 16 (66.7%) presented within 4 weeks after first SARS-CoV2 vaccine. Fourteen had received the AstraZeneca vaccine and one each, the Pfizer and Moderna vaccines. The final diagnosis was Guillain-Barré syndrome (GBS) in 12 and acute-onset chronic inflammatory demyelinating polyneuropathy in 4. Among AstraZeneca vaccine recipients, facial weakness in nine persons (64.3%), bulbar weakness in seven (50%), and the bifacial weakness and distal paresthesias GBS variant in three (21.4%), were more common than in historical controls (P =.01; P =.004, and P =.002, respectively). A 2.6-fold (95% confidence interval: 1.98–3.51) increase in admissions for acute-onset polyradiculoneuropathy was noted during the studied time frame, compared to the same period in the previous 3 years. Discussion: Despite a low risk, smaller than that of SARS-CoV2 infection and its complications, exposure to the first dose of AstraZeneca SARS-CoV2 vaccine may be a risk factor for acute-onset polyradiculoneuropathy, characterized by more common cranial nerve involvement

Joint angle-specific neuromuscular time course of recovery after isometric resistance exercise at shorter and longer muscle lengths

Resistance training at longer muscle lengths induces greater muscle hypertrophy and different neuromuscular functional adaptations than training at shorter muscle lengths. However, the acute time course of recovery of neuromuscular characteristics after resistance exercise at shorter and longer muscle lengths in the quadriceps has never been described. Eight healthy young participants (4 M, 4 F) were randomly assigned to perform four sets of eight maximal isometric contractions at shorter (SL; 50° knee flexion) or longer (LL; 90° knee flexion) muscle lengths in a crossover fashion. During exercise, peak torque (PT), muscle activity [electromyogram (EMG)], and internal muscle forces were assessed. PT and EMG at shorter (PT50, EMG50) and longer (PT90, EMG90) muscle lengths, creatine kinase (CK), and muscle soreness were measured at baseline, immediately after exercise (Post), after 24 h (24 h), and after 48 h (48 h). During exercise, EMG (P ¼ 0.002) and internal muscle forces (P ¼ 0.017) were greater in LL than in SL. During recovery, there was a main effect of exercise angle, with PT50 (P ¼ 0.002), PT90 (P ¼ 0.016), and EMG50 (P ¼ 0.002) all significantly reduced to a greater degree in LL compared with SL. CK and muscle soreness increased after resistance exercise, but there were no differences between SL and LL. The present results suggest that if the preceding isometric resistance exercise is performed at longer muscle lengths, function and muscle activity at shorter and longer muscle lengths are inhibited to a larger degree in the subsequent recovery period. This information can be used by practitioners to manipulate exercise prescription. NEW & NOTEWORTHY: Despite the established long-term benefits of training at longer muscle lengths for muscle size and strength, acutely performing resistance exercise at longer muscle lengths may require a longer time course of neuromuscular recovery compared with performing resistance exercises at shorter muscle lengths. Furthermore, there appear to be different joint angle-specific recovery profiles, depending on the muscle length of the preceding exercise

Tendances internationales de la mortalité maternelle et infantile en Afrique de 1990-2016

Objectif général: savoir la tendance annuelle de réduction du taux de mortalité maternelle et infantile entre 1990 à 2015 et 2016 respectivement. Objectifs spécifiques: savoir les tendances annuelles de réduction de la mortalité maternelle dans les cinq régions de l‘Afrique; savoir les pays africains qui ont atteint le quatrième Objectif du Millénaire pour le Développement (OMD4); savoir les tendances annuelles de mortalité infantile dans les cinq régions de l‘Afrique; savoir les pays africains ayant atteint le cinquième Objectif du Millénaire pour le Développement(OMD5); savoir la région dont les pays ont les meilleures tendances annuelles de réduction de la mortalité maternelle et infantile.Programa de Doctorado en Ciencias de la Salud (RD 99/2011)Osasun Zientzietako Doktoretza Programa (ED 99/2011

Programa de reducción de la incidencia de la mortalidad materna en zonas rurales de la región del Centro-Camerún

Los objetivos que planteamos con este plan se fundamentan en los tres determinantes de la salud que son: los factores genéticos, el estilo de vida y el medio ambiente, y la asistencia sanitaria (Dever). En Camerún, la asistencia sanitaria para el parto en las zonas rurales se ha reducido. El riesgo de morir de las mujeres, durante el embarazo o el parto, es muy considerable en las zonas rurales de la región del centro, en Camerún. El objetivo general del plan de prevención que proponemos es reducir la incidencia de la mortalidad materna, mejorando la salud materna de las mujeres procedentes del medio rural. Sin olvidar la importancia de los cambios en la legislación y en la política en general orientados a la reducción de la mortalidad materna (planificación de la familia), el plan estratégico que proponemos valora más las intervenciones de la comunidad, el apoyo de la familia y la capacitación de las parteras tradicionales.Máster Universitario en Salud Pública por la Universidad Pública de NavarraOsasun Publikoko Unibertsitate Masterra Nafarroako Unibertsitate Publikoa

Influence of exercise intensity on the tendon mechanical properties of older individuals.

Approximately one-third of people aged over 65 fall at least once a year and about half of these do so recurrently. The ability to maintain balance or stability has previously been associated with lower limb tendon structural and mechanical properties, with stiffer tendon structures associated with increased balance ability (Onambele et al., 2006: Journal of Applied Physiology, 100, 2048–2056). Increased tendon compliance is not an irreversible ageing effect. It has been shown that following 14 weeks high intensity resistance training (~80% one repetition maximum (1RM)), tendon stiffness was increased in an elderly population (Reeves et al., 2003: Journal of Physiology, 548, 971–981). However, the majority of resistance exercise prescribed for an elderly population is of lower intensity than 80% 1RM. It is possible that this lower intensity resistance exercise does not produce the required stimulus for tendon adaptation

The individual and combined effects of obesity- and ageing-induced systemic inflammation on human skeletal muscle properties.

BACKGROUND/OBJECTIVES: The purpose of this study was to determine whether circulating pro-inflammatory cytokines, elevated with increased fat mass and ageing, were associated with muscle properties in young and older people with variable adiposity. SUBJECTS/METHODS: Seventy-five young (18-49 yrs) and 67 older (50-80 yrs) healthy, untrained men and women (BMI: 17-49 kg/m(2)) performed isometric and isokinetic plantar flexor maximum voluntary contractions (MVCs). Volume (Vm), fascicle pennation angle (FPA), and physiological cross-sectional area (PCSA) of the gastrocnemius medialis (GM) muscle were measured using ultrasonography. Voluntary muscle activation (VA) was assessed using electrical stimulation. GM specific force was calculated as GM fascicle force/PCSA. Percentage body fat (BF%), body fat mass (BFM), and lean mass (BLM) were assessed using dual-energy X-ray absorptiometry. Serum concentration of 12 cytokines was measured using multiplex luminometry. RESULTS: Despite greater Vm, FPA, and PCSA (P0.05), while IL-8 correlated with VA in older but not young adults (r⩾0.378, P⩽0.027). TNF-alpha correlated with MVC, lean mass, GM FPA and maximum force in older adults (r⩾0.458; P⩽0.048). CONCLUSIONS: The age- and adiposity-dependent relationships found here provide evidence that circulating pro-inflammatory cytokines may play different roles in muscle remodelling according to the age and adiposity of the individual.International Journal of Obesity accepted article preview online, 29 August 2016. doi:10.1038/ijo.2016.151