Training History-Dependent Functional Role of EMG Model-Predicted Antagonist Moments in Knee Extensor Moment Generation in Healthy Young Adults

Resistance training (RT) improves the skeletal muscle’s ability to generate maximal voluntary force and is accompanied by changes in the activation of the antagonist muscle which is not targeted primarily by RT. However, the nature and role of neural adaptation to RT in the antagonist muscle is paradoxical and not well understood. We compared moments, agonist muscle activation, antagonist activation, agonist-antagonist coactivation, and electromyographic (EMG) model-predicted moments generated by antagonist hamstring muscle coactivation during isokinetic knee extension in leg strength-trained (n = 10) and untrained (n = 11) healthy, younger adults. Trained vs. untrained adults were up to 58% stronger. During knee extension, hamstring activation was 1.6-fold greater in trained vs. untrained adults (p = 0.022). This hamstring activation produced 2.6-fold greater model-predicted antagonist moments during knee extension in the trained (42.7 ± 19.55 Nm) vs. untrained group (16.4 ± 12.18 Nm; p = 0.004), which counteracted (reduced) quadriceps knee extensor moments ~43 Nm (0.54 Nm·kg−1) and by ~16 Nm (0.25 Nm·kg−1) in trained vs. untrained. Antagonist hamstring coactivation correlated with decreases and increases, respectively, in quadriceps moments in trained and untrained. The EMG model-predicted antagonist moments revealed training history-dependent functional roles in knee extensor moment generation.

Premenopausal Bilateral Oophorectomy Effects on Clinical and Real-World Physical Function Measures

Women with premenopausal bilateral oophorectomy (PBO) are at increased risk for physical function (PF) declines. This study investigated the relationships of field-based physical activity measures with clinical PF and strength parameters in post-menopausal women with and without PBO. Women with (n=21; age=64±4 years; BMI=32±8 kg.m-2) and without (n=15; age=67±6 years; BMI=28±6 kg.m-2) PBO performed PF and strength tests (walking speed, distance walked, short physical performance battery (SPBB), leg and chest strength), and wore ankle accelerometers for 7 days (daily step count and loading index [the cumulative sum of each step’s skeletal loading]). Age, BMI, step count and loading index were entered into stepwise multiple regression to identify significant predictors of PF and strength parameters. Step count was a predictor of SPBB score in both groups. In women without PBO, step count was a predictor of walking speed; loading index was a predictor of leg strength; step count and loading index were predictors of distance; and step count and age were predictors of chest strength. For PBO women, loading index and BMI were predictors of walking speed and distance; BMI was a predictor of leg strength; and there were no predictors of chest strength. These data suggest while field-based physical activity was strongly and positively associated with clinical PF and strength measures for women without PBO, BMI was a dominant negative factor for PF in women with PBO. Future work will include a larger sample size and additional confounders to further elucidate underlying factors of reduced PF and mobility after PBO.

Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants

Although previous studies have highlighted the association between physical activity and lower extremity function (LEF) in elderly individuals, the mechanisms underlying this relationship remain debated. Our recent work has recognized the utility of nonlinear trimodal regression analysis (NTRA) parameters in characterizing changes in soft tissue radiodensity as a quantitative construct for sarcopenia in the longitudinal, population-based cohort of the AGES-Reykjavík study. For the present work, we assembled a series of prospective multivariate regression models to interrogate whether NTRA parameters mediate the 5-year longitudinal relationship between physical activity and LEF in AGES-Reykjavík participants. Healthy elderly volunteers from the AGES-Reykjavík cohort underwent mid-thigh X-ray CT scans along with a four-part battery of LEF tasks: normal gait speed, fastest-comfortable gait speed, isometric leg strength, and timed up-and-go. These data were recorded at two study timepoints which were separated by approximately 5 years: AGES-I (n = 3157) and AGES-II (n = 3098). Participants in AGES-I were likewise administered a survey to approximate their weekly frequency of engaging in moderate-to-vigorous physical activity (PAAGES-I). Using a multivariate mediation analysis framework, linear regression models were assembled to test whether NTRA parameters mediated the longitudinal relationship between PAAGES-I and LEFAGES-II; all models were covariate-adjusted for age, sex, BMI, and baseline LEF, and results were corrected for multiple statistical comparisons. Our first series of models confirmed that all four LEF tasks were significantly related to PAAGES-I; next, modelling the relationship between PAAGES-I and NTRAAGES-II identified muscle amplitude (Nm) and location (μm) as potential mediators of LEF to test. Finally, adding these two parameters into our PAAGES-I → LEFAGES-II models attenuated the prior effect of PAAGES-I; bootstrapping confirmed Nm and μm as significant partial mediators of the PAAGES-I → LEFAGES-II relationship, with the strongest effect found in isometric leg strength. This work describes a novel approach toward clarifying the mechanisms that underly the relationship between physical activity and LEF in aging individuals. Identifying Nm and μm as significant partial mediators of this relationship provides strong evidence that physical activity protects aging mobility through the preservation of both lean tissue quantity and quality.

Laparoscopic transdiaphragmatic approach to a thoracic paravertebral hydatid cyst presenting with compression myelopathy

An elderly gentleman presented with heaviness over the right side of the chest, lower back pain and difficulty in walking for the last 6 months. He also reported of progressive weakness of the left leg associated with tingling and numbness for 2 months. Imaging studies revealed a large hydatid cyst in the right thoracic cavity compressing the spinal cord. The patient was prescribed a 14-day course of albendazole therapy. He underwent laparoscopic transdiaphragmatic deroofing and evacuation of the cyst. Postoperative recovery was uneventful. The patient started showing symptom relief from day 1 of surgery and by day 3, his right leg strength and sensation recovered remarkably. Echinococcal cyst is a zoonotic disease that can affect any part of the body. Vertebral involvement and spinal cord compression is a rare manifestation of echinococcal disease. Such cases pose diagnostic and therapeutic challenges and require a multidisciplinary approach to treat them successfully.

Diverse Motor Performances Are Related to Incident Cognitive Impairment in Community-Dwelling Older Adults

Objective: Late-life cognitive impairment is heterogeneous. This study examined to what extent varied motor performances are differentially associated with incident Alzheimer’s dementia (AD) and incident mild cognitive impairment (MCI) in older adults.Design: Nested substudy.Setting: Communities across metropolitan Chicago.Participants: African American (N = 580) and European American (N = 580) adults without dementia, propensity-balanced by age (mean = 73.2; SD = 6.0), sex (78.4% women), education (mean = 15.6; SD = 3.3) and number of follow ups.Measurements: Cognitive status was assessed annually and based in part on a composite measure of global cognition including 17 cognitive tests. A global motor score was based on 10 motor performances from which 4 motor domains were computed including hand dexterity, hand strength, gait function, and leg strength.Results: During 7 years of follow-up, 166 of 1,160 (14.3%) developed AD. In a proportional hazards model controlling for age, sex, education, and race, each 1-SD higher baseline global motor score was associated with about a 20% reduction in the risk of AD (hazard ratio: 0.81; 95% CI: 0.68, 0.97). Higher baseline motor function was also associated with decreased risk of incident MCI (hazard ratio: 0.79; 95% CI: 0.68, 0.92). Hand dexterity, hand strength and gait function but not leg strength were associated with incident AD and MCI. When including all four motor domains in the same model, results remained the same for incident MCI, while for incident AD, the association with hand strength remained significant.Conclusion: Diverse motor performances are associated with late-life cognitive impairment. Further work is needed to identify specific motor performances that may differentiate adults at risk for future MCI or AD dementia.

Hubungan antara sindrom metabolik dengan kebugaran jasmani pada lansia

Prevalensi sindrom metabolik pada lansia cukup tinggi. Sindrom metabolik dapat dicegah salah satunya dengan aktivitas fisik. Aktivitas fisik juga dapat meningkatkan kebugaran kardiorespirasi, kelenturan sendi, keseimbangan dan kekuatan otot. Penelitian ini bertujuan untuk mengetahui hubungan antara sindrom metabolik dengan kebugaran kardiorespirasi, fleksibilitas, kekuatan, dan keseimbangan pada lansia. Penelitian ini merupakan penelitian cross sectional dengan teknik consecutive sampling pada 118 lansia di Yogyakarta. Sindrom metabolik ditetapkan berdasarkan kriteria diagnosis dari Adult Treatment Panel. Instrumen yang digunakan untuk mengumpulkan data adalah tes jalan 6 menit (6-minute walking test), sit and reach, hand grip dynamometer, leg and back dynamometer dan berdiri satu kaki. Teknik analisis dengan menggunakan uji korelasi Spearman. Hasil dari penelitian menunjukkan bahwa sebanyak 32 lansia mengalami sindrom metabolik. Tujuh puluh dari 118 orang memiliki data yang lengkap untuk analisis korelasi. Terdapat korelasi antara sindrom metabolik dengan kekuatan otot tungkai/leg strength (r=-0,295, p=0,013) dan keseimbangan (r=-0,282, p=0,018), namun tidak ada korelasi antara sindrom metabolik dengan kekuatan peras tangan/hand grip, kekuatan otot punggung/back strength (p=0,405), kebugaran kardiorespirasi (p=0,103) dan fleksibilitas (p=0,488). Dapat disimpulkan bahwa lansia yang terdiagnosis mengalami sindrom metabolik cenderung mengalami pelemahan kekuatan tungkai dan penurunan keseimbangan. Oleh karenanya, lansia perlu melakukan aktivitas fisik untuk meningkatkan kekuatan otot tungkai dan keseimbangan. The Correlation between metabolic syndrome and physical fitness in elderly AbstractThe prevalence of metabolic syndrome in the elderly is quite high. One way to prevent metabolic syndrome is by being physical active. Physical activity can also improve cardiorespiratory fitness, joint flexibility, balance and muscle strength. This study aimed to determine the relationship between metabolic syndrome and cardiorespiratory fitness, flexibility, strength, and balance in the elderly. This study was a cross sectional study with a consecutive sampling technique on 118 elderly people in Yogyakarta. Metabolic syndrome was defined based on the diagnostic criteria from the Adult Treatment Panel. The instruments used to collect the data were a 6-minute walking test, sit and reach, hand grip dynamometer, leg and back dynamometer and standing on one leg. The analysis technique used the Spearman correlation test. The results of the study showed that 32 elderly had metabolic syndrome. Seventy out of 118 people had complete data for correlation analysis. There was a correlation between metabolic syndrome and leg muscle strength (r = -0.295, p = 0.013) and balance (r = -0.282, p = 0.018), but there was no correlation between metabolic syndrome and hand grip strength. back muscle strength (p = 0.405), cardiorespiratory fitness (p = 0.103) and flexibility (p = 0.488). It can be concluded that the elderly who are diagnosed with metabolic syndrome tend to experience weakened leg strength and decreased balance. Therefore, the elderly need to do physical activity to improve leg muscle strength and balance.

Prevalence of Metabolic Syndrome According to Absolute and Relative Values of Muscle Strength in Middle-Aged and Elderly Women

Metabolic syndrome (MetS) increases with age, obesity, low physical activity, and decreased muscle strength. Although many studies have reported on grip strength and MetS, few studies have been conducted on leg strength. The purpose of this study was to analyze the prevalence of MetS according to absolute and relative leg strength values in middle-aged and older women. The participants were 1053 women who visited the healthcare center: middle-aged (n = 453) and older (n = 601). MetS was diagnosed using the criteria established by the third report of the National Cholesterol Education Program Adult Treatment Panel III and the World Health Organization’s Asia Pacific guidelines for waist circumference. For leg strength, knee flexion and extension were performed using isokinetic equipment. Grip strength was measured using a grip dynamometer and classified into quartiles. Analysis of prevalence using logistic regression showed that MetS was present in 21.2% of middle-aged and 39.4% of older women. The lowest relative leg extension increased 2.5 times in the middle-aged and 1.5 times in older women (p < 0.05). However, leg flexion did not have a significant prevalence in either age group. The prevalence of MetS in middle-aged and older women with the lowest relative grip strength increased 1.5 and 1.2 times, respectively. Conversely, the lower the absolute leg extension strength, the lower the MetS prevalence was at 0.520 in middle-aged and 0.566 in older women (p < 0.05). In conclusion, the prevalence of MetS increased in women with low relative grip and leg strengths. Specifically, the lower the relative leg extension muscle strength, the higher the prevalence of MetS. In addition, the prevalence of MetS increased in the high-frequency alcohol consumption and non-physical activity group.

Blood flow restriction exercise to attenuate postoperative loss of function after total knee replacement: a randomized pilot study

Aging well is directly associated with a healthy lifestyle. The focus of this paper is to relate that attenuation of postoperative loss of muscle function after a total knee arthroplasty (TKA) is an important consideration. Because patients usually do not tolerate standard high-resistance exercise in the preoperative or postoperative period, they often experience a decline in strength and function. Therefore, we tested the feasibility and acceptability of an alternative low-resistance exercise protocol with blood flow restriction (BFR) using a tourniquet in the preoperative period for patients awaiting TKA. We recruited patients undergoing a TKA and randomized six to the BFR exercise for 4 weeks prior to surgery and four to standard of care (no exercise). We measured physical function using the Short Physical Performance Battery (SPPB), the 6-Minute Walk Test (6MWT), leg strength (peak torque), and pain (numerical pain score) 4 to 5 weeks preoperatively and 2 weeks postoperatively. The clinical management, e.g., anesthetic management, did not differ between groups. No complications were observed. Our findings demonstrate the feasibility and acceptability of the BFR intervention. Although preliminary and not powered for comparison, the BFR group demonstrated less decline in SPPB following surgery (−2.2, 95%CI:−4.4,0.1) compared to the no exercise group (−4.8, 95%CI:−7.8,−1.7). No differences were noted for the 6MWT, leg strength, and pain measurements. We conclude that preoperative low-resistance exercise using the BFR is feasible and acceptable, and this test warrants investigation as an intervention to potentially attenuate the postoperative loss of physical function after TKA.