1,720,968 research outputs found
The impact of obesity on muscle function in older adults: from clinical evaluation to lifestyle management
Full text linkIn the geriatric population, obesity and sarcopenia constitute two important public concerns due to their association with disability, loss of independence, comorbidity, and mortality. Only few studies previously evaluated the impact of obesity on the in vivo muscle strength, power, and physical function in the older population, particularly on the lower extremities. This is surprising, since particularly the decline of lower body physical function negatively affects important daily activities. In older adults the role of obesity and adipose tissue on muscle function decline is complex and not completely understood. Furthermore, the possible contribution of lower limb muscles in the evaluation of muscle weakness has been poorly investigated. Finally, various studies exist on the possible approaches using exercise and nutrition to treat and to ameliorate obesity, dynapenia and sarcopenia; discrepancies are instead presented on the potential beneficial effects associated with the supplementations compared to exercise alone, leaving open questions about the best treatments to adopt in this population. Therefore, the goals of this thesis are: i) to determine the impact of obesity on the in vivo lower limbs muscle strength and function in older adults of both sexes; ii) to investigate the associations between lower limbs muscle strength and function and the handgrip dynamometer and the possible contribution to predict the appendicular muscle mass; iii) to propose an intervention protocol aimed at improving or reversing obesity and sarcopenia condition. Chapter one explored the literature around the effects of obesity in the geriatric population. A particular emphasis is made on the important role of maintaining and assessing muscle strength, muscle mass and function. Additionally, an overview of different strategies for treating or reversing obesity and sarcopenia through exercise and nutrition are provided. Chapter two presents the consequences of obesity on the lower limbs’ muscles, adding new reference data of knee extensors and knee flexors strength and power in geriatric population of both sexes. Chapter three focuses on the tools used for evaluating muscle weakness. In this context, the role of handgrip dynamometer as a proxy of muscle strength is argued with a comprehensive narrative review and an experimental study. In the latter, the associations between upper vs lower limbs muscle strength and physical function are discussed looking at the possible sex differences in geriatric population. Chapter four describes the preliminary results on the role of a 5-month controlled diet plus strength training alone or amino acids supplementation in older adults with obesity, dynapenia and sarcopenia. After the intervention, the changes in several outcomes (i.e., on body composition, upper and lower limbs muscle strength and power, physical performance) are described, by comparing the different interventional groups. Lastly, chapter five outlines the main results of each study and presents a general conclusion with proposals for future directions needed on these research topics
Sprint running: how changes in step frequency affect running mechanics and leg spring behaviour at maximal speed
No full textThe purpose of this study was to investigate the changes in selected biomechanical variables in 80-m maximal sprint runs while imposing changes in step frequency (SF) and to investigate if these adaptations differ based on gender and training level. A total of 40 athletes (10 elite men and 10 women, 10 intermediate men and 10 women) participated in this study; they were requested to perform 5 trials at maximal running speed (RS): at the self-selected frequency (SFs) and at SF ±15% and ±30%SFs. Contact time (CT) and flight time (FT) as well as step length (SL) decreased with increasing SF, while kvert increased with it. At SFs, kleg was the lowest (a 20% decrease at ±30%SFs), while RS was the largest (a 12% decrease at ±30%SFs). Only small changes (1.5%) in maximal vertical force (Fmax) were observed as a function of SF, but maximum leg spring compression (ΔL) was largest at SFs and decreased by about 25% at ±30%SFs. Significant differences in Fmax, Δy, kleg and kvert were observed as a function of skill and gender (P < 0.001). Our results indicate that RS is optimised at SFs and that, while kvert follows the changes in SF, kleg is lowest at SFs
Knee flexor and extensor torque ratio in elderly men and women with and without obesity: a cross-sectional study
No full textBackground: With aging and obesity lower limb torque deteriorates. Importantly, the ratio between knee flexor (KF) and extensor (KE) torque is an indicator of joint stability. Aims: We compared KF torque and KF/KE ratio in older subjects of both sexes with obesity (OB) or without (NOB) obesity. Methods: The maximal torque during KE and KF isokinetic contractions were evaluated at: 60, 90, 150, 180 and 210 deg/s in 89 elderly (68 ± 5 years) subjects with NOB (BMI < 30 kg/m2) and OB (BMI ≥ 30 kg/m2). Values were normalised for body weight (BW) and leg lean mass (i.e., muscle quality). Results: At all speeds men had higher absolute KF values (P < 0.001). When values were normalised for BW, sex differences remain in favour of men (P < 0.001) with lower values in both groups with OB than NOB (P < 0.001). Muscle quality and KF/KE ratio were lower in OB than NOB (P < 0.001). Conclusions: The KF torque and KF/KE ratio decline with aging and with OB. In all groups, the KF/KE ratio was below the joint stability threshold. Thus, exercise physiologists should include exercises designed to train both KE and KF in older subjects with OB
Prolonged unsupervised Nordic walking and walking exercise following six months of supervision in adults with overweight and obesity: a randomised clinical trial
No full textBackground and aims: This study is a randomized trial that examined the effects of 6 months of unsupervised Nordic walking (NW) and walking (W) exercise following 6 months of supervised training in overweight/obese adults. Methods and results: After a 6-month program of diet and supervised training participants (n = 27) of NW (66 ± 7 yrs, body mass index (BMI) 34 ± 5) and W (66 ± 8 yrs, BMI 32 ± 5) group continue the training without supervision for other 6 months. Steps count and mean heart rate (HRmean) were performed in each session; anthropometric and body composition, aerobic capacity and strength of the upper and lower limbs were evaluated at baseline, after 6 months of supervised and 6 months of unsupervised training. In the unsupervised training, monthly sessions and steps count decreased over time in both groups (p < 0.05), with no significant changes in HRmean. Compared to the supervised phase, adherence decreased significantly only in the W group in the last 3 months of unsupervised training. Compared to baseline in both groups BMI did not change, but W group lost total fat; only the NW group maintained (p < 0.05) the gains in arm curl (33%) and chair stand (31%); both groups improved in six-minute walking test (p < 0.05). Conclusion: Despite unsupervised training was not effective for a further increase in performance, participants, especially in NW, maintained some of the improvements achieved during the supervision. However, the presence of instructor that guides training, may enhance adherence and health benefits of NW and W exercise. Clinical trial registration: clinicaltrials.gov Identifier: NCT03212391 (July 11, 2017)
Evaluating handgrip strength and functional tests as indicators of gait speed in older females
Full text linkIntroductionWith aging, females often experience greater declines in functional capacity [e.g., gait speed (GS)] compared to males, highlighting the need for sex-difference considered in screening and intervention planning. In certain contexts, assessing GS may not be feasible. Handgrip strength (HGS) commonly used as a surrogate measure for physical performance, also serves as an indirect indicator of muscle strength in the lower limbs. This cross-sectional study aims to investigate the associations between HGS and common functional tests and to determine the optimal cut-off values for these tests in assessing GS.Methods142 community-dwelling older females aged 60–80 years old (mean age: 75 ± 6 years) were evaluated with HGS, the 30-second arm curl (30 s-AC), 30-second chair stand (30 s-CS), the Short Physical Performance Battery (SPPB), and the 8-foot Up & Go (8-UG) test. Pearson's correlation (r) was used to assess the strength of associations between HGS and functional variables, while multiple linear regression models identified determinants of GS. Receiver operating characteristic (ROC) curves were employed to evaluate the effectiveness of various tests in detecting slow GS (<1.0 m/s), by means of the area under the curve (AUC), sensitivity, and specificity.ResultsHGS showed positive significant (p < 0.001) associations with 30 s-AC (r = 0.499), SPPB (r = 0.447), and 30 s-CS (r = 0.329). Standardised coefficients of the linear models were: 30 s-AC (β=0.593), 30 s-CS (β=0.513), 5-CS (β=−0.431), and HGS (β=0.475) (all p < 0.001). ROC analysis revealed the following results: 30 s-AC (AUC = 0.80, cut-off=∼16 repetitions, sensitivity 83%, specificity 36%), 30 s-CS (AUC = 0.74; cut-off=∼13 repetitions, sensitivity 78%, specificity 64%), and 5-CS (AUC = 0.75, cut-off = 10.0 s, sensitivity 81%, specificity 57%), HGS (AUC = 0.73, cut-off=∼20 kg, sensitivity 79%, specificity 46%).DiscussionWe found that HGS was moderately-to-weakly associated with functional outcomes in older females, indicating that it may not reflect the overall body functional capacity. Despite similar AUCs across all tests, the 30 s-CS and 5-CS showed a better balance of sensitivity and specificity, making them potential indicators of slow GS compared to HGS and 30 s-AC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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