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

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

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

Segregating the Distinct Effects of Sedentary Behavior and Physical Activity on Older Adults' Cardiovascular Profile: Part 2-Isotemporal Substitution Approach.

The aim of the study was to provide an isotemporal substitution model to predict how changes in physical behavior may affect the cardiovascular parameters (CVPs) of older adults. Methods: Participants wore a thigh-mounted accelerometer for 7 days. Phenotype of the carotid, brachial, and popliteal artery was conducted using ultrasound. Isotemporal substitution was used to simulate the degree to which replacing 1 hour of physical behavior with another would affect CVP. Results: Substitution of sedentary behavior with Standing and sporadic moderate- to vigorous-intensity physical activity (MVPA accumulated in bouts <10 min) would reduce resting heart rate [−6.20 beats per minute (−12.1 to −0.22) and −3.72 beats per minute (−7.01 to −0.44), respectively]. Substitution of sedentary behavior with light-intensity physical activity would reduce carotid artery diameter [−0.54 mm (−1.00 to −0.07)]. Substitution of Standing with sporadic MVPA would increase popliteal artery diameter [1.31 mm (0.11 to 2.51)]. Conclusions: Our modeling suggests that an accumulation of MVPA bouts that are shorter than the recommended 10-minute minimum may still improve CVP, with lower intensity physical activity also influencing CVP. Our findings are a promising avenue for lifestyle interventions in older adults to reduce the aging effects on CVP for those who cannot engage or sustain sufficient MVPA

Impaired glucose tolerance in adults with Duchenne and Becker muscular dystrophy

The aim of this study was to determine the response to an oral glucose tolerance test (OGTT) in adult males with Becker muscular dystrophy (BMD) and Duchenne muscular dystrophy (DMD), and to investigate whether body composition contributes to any variance in the glucose response. Twenty-eight adult males with dystrophinopathy (BMD, n = 13; DMD, n = 15) and 12 non-dystrophic controls, ingested 75 g oral anhydrous glucose solution. Fingertip capillary samples were assessed for glucose at 30-min intervals over 2-h post glucose ingestion. Fat free mass relative to body mass (FFM/BM) and body fat (BF%) was assessed using bioelectrical impedance. Vastus lateralis muscle anatomical cross sectional area (VL ACSA) was measured using B-mode ultrasonography. Blood glucose was higher in MD groups than control at 60, 90 and 120 min post ingestion of glucose. Compared to controls, FFM/BM and VL ACSA were lower in MD groups compared to controls (p < 0.001). Glucose tolerance values at 120 min were correlated with FFM/BM and BF% in the BMD group only. Our results suggest that glucose tolerance is impaired following OGTT in adult males with BMD and DMD. It is recommended that adults with BMD and DMD undertake routine glucose tolerance assessments to allow early detection of impaired glucose tolerance

Low antiretroviral therapy uptake and low early retention among pregnant women who tested positive for human immunodeficiency virus in informal health centers in urban and semi-rural settings in Cameroon: a prospective cohort study

IntroductionDespite the efforts of Cameroon’s Ministry of Public Health against informal health centers (IHCs) because of their illegitimacy, the number of IHCs is increasing in Cameroon. Most of these IHCs have antenatal care services and screen pregnant women for HIV. However, nothing is known about the subsequent outcomes of those who tested positive for HIV. This study aimed to assess the initiation of antiretroviral therapy (ART) in ART-naïve pregnant women screened HIV positive in IHCs within three months of diagnosis and their ART retention at three months post-initiation. In addition, we sought to identify the factors associated with ART non-initiation in this population.MethodsMay 01, 2019 to August 31, 2020, we carried out a prospective cohort study of ART-naïve pregnant women who attended their first antenatal care visit and screened HIV positive at IHCs in the cities of Douala and Ebolowa in Cameroon. Standardized questionnaires were used to interview consenting participants at three points: the day of the delivery of the antenatal HIV test result, three months later, and three months after ART initiation. The data collected were entered into KoboCollect and analyzed using SPSS V23.0 software. The Chi-square test was used to compare proportions, Kaplan Meier techniques and Cox proportional hazards regression was used to estimate retention in ART and identify factors associated with ART non-retention, respectively.Results and discussionA total of 85 ART-naïve pregnant women living with HIV were enrolled in the study. The median age and gestational age at the first antenatal care visit were 29 years (interquartile range (IQR), 2333.5) and 28weeks of amenorrhea (IQR, 2032), respectively. Only 34% (29/85) initiated ART, and 65.5% (19/29) of the initiators were retained in ART three months later. Lack of perceived self-efficacy to initiate ART (adjust Hazard Ratio = 5.57, 90% CI: 1.29 to 24.06), increased the probability of not be retaining in ART by any time during three months post initiation. Given the low ART uptake and the low retention in care among pregnant women living with HIV screened in IHCs, PMTCT policies in Cameroon should pay greater attention to this population, to facilitate their continuum of PMTCT care