105 research outputs found

    All-Cause Mortality Risk of Metabolically Healthy Obese Individuals in NHANES III

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    Mortality risk across metabolic health-by-BMI categories in NHANES-III was examined. Metabolic health was defined as: (1) homeostasis model assessment-insulin resistance (HOMA-IR) <2.5; (2) ≤2 Adult Treatment Panel (ATP) III metabolic syndrome criteria; (3) combined definition using ≤1 of the following: HOMA-IR ≥1.95 (or diabetes medications), triglycerides ≥1.7 mmol/L, HDL-C <1.04 mmol/L (males) or <1.30 mmol/L (females), LDL-C ≥2.6 mmol/L, and total cholesterol ≥5.2 mmol/L (or cholesterol-lowering medications). Hazard ratios (HR) for all-cause mortality were estimated with Cox regression models. Nonpregnant women and men were included (n=4373, mean ± SD, age 37.1±10.9 years, BMI 27.3±5.8 kg/m2, 49.4% female). Only 40 of 1160 obese individuals were identified as MHO by all definitions. MHO groups had superior levels of clinical risk factors compared to unhealthy individuals but inferior levels compared to healthy lean groups. There was increased risk of all-cause mortality in metabolically unhealthy obese participants regardless of definition (HOMA-IR HR 2.07 (CI 1.3–3.4), P<0.01; ATP-III HR 1.98 (CI 1.4–2.9), P<0.001; combined definition HR 2.19 (CI 1.3–3.8), P<0.01). MHO participants were not significantly different from healthy lean individuals by any definition. While MHO individuals are not at significantly increased risk of all-cause mortality, their clinical risk profile is worse than that of metabolically healthy lean individuals

    Muscle damage and inflammation after eccentric exercise: can the repeated bout effect be removed?

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    The current consensus in exercise physiology is that the repeated bout effect always appears after few eccentric exercise sessions. This is the first attempt to challenge this tenet, by exploiting specificity in muscle plasticity. More specifically, we examined whether the opposing adaptations in muscle induced after concentric and eccentric exercise can attenuate and/or remove the repeated bout effect. Seventeen young men were randomly assigned into one of the following groups: (1) the alternating eccentric-concentric exercise group; and (2) the eccentric-only exercise group. Both groups performed 8 weeks of resistance exercise using the knee extensors of both legs on an isokinetic dynamometer. The alternating eccentric-concentric exercise group performed an alternating exercise protocol, switching between eccentric-only and concentric-only exercise every 4 weeks, while the eccentric-only group performed eccentric exercise. Evaluation of muscle damage using physiological (isometric torque, delayed onset muscle soreness, and range of movement) and biochemical (creatine kinase) markers and inflammation (C-reactive protein) was performed at weeks 1, 5, and 10. Baseline isometric peak torque was also evaluated at week 14 after another cycle (4 weeks) of alternating or eccentric-only exercise training. In the alternating eccentric-concentric exercise group, the concentric exercise training performed prior to eccentric exercise reduced dramatically the repeated bout effect by reversing muscle back to its unaccustomed state. On the contrary, the eccentric-only exercise group exhibited a typical manifestation of the repeated bout effect. Interestingly, muscle strength was elevated similarly for both alternating and eccentric-only exercise groups after 13 weeks of training. The alternating eccentric-concentric exercise scheme, implemented in the present study, has for the first time successfully overcame the repeated bout effect. The similarity in muscle strength measurements following the two protocols is against the notion that inflammation plays an important role in exercise-induced adaptations in muscle

    Superior effects of eccentric to concentric knee extensor resistance training on physical fitness, insulin sensitivity and lipid profiles of elderly men

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    It has been reported that eccentric training of knee extensors is effective for improving blood insulin sensitivity and lipid profiles to a greater extent than concentric training in young women. However, it is not known whether this is also the case for elderly individuals. Thus, the present study tested the hypothesis that eccentric training of the knee extensors would improve physical function and health parameters (e.g., blood lipid profiles) of older adults better than concentric training. Healthy elderly men (60–76 years) were assigned to either eccentric training or concentric training group (n=13/group), and performed 30–60 eccentric or concentric contractions of knee extensors once a week. The intensity was progressively increased over 12 weeks from 10 to 100% of maximal concentric strength for eccentric training and from 50 to 100% for concentric training. Outcome measures were taken before and 4 days after the training period. The results showed that no sings of muscle damage were observed after any sessions. Functional physical fitness (e.g., 30-s chair stand) and maximal concentric contraction strength of the knee extensors increased greater (P ≤ 0.05) after eccentric training than concentric training. Homeostasis model assessment, oral glucose tolerance test and whole blood glycosylated hemoglobin

    Early structural remodeling and deuterium oxide-derived protein metabolic responses to eccentric and concentric loading in human skeletal muscle

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    We recently reported that the greatest distinguishing feature between eccentric (ECC) and concentric (CON) muscle loading lays in architectural adaptations: ECC favors increases in fascicle length (Lf), associated with distal vastus lateralis muscle (VL) hypertrophy, and CON increases in pennation angle (PA). Here, we explored the interactions between structural and morphological remodeling, assessed by ultrasound and dual x‐ray absorptiometry (DXA), and long‐term muscle protein synthesis (MPS), evaluated by deuterium oxide (D2O) tracing technique. Ten young males (23 ± 4 years) performed unilateral resistance exercise training (RET) three times/week for 4 weeks; thus, one‐leg trained concentrically while the contralateral performed ECC exercise only at 80% of either CON or ECC one repetition maximum (1RM). Subjects consumed an initial bolus of D2O (150 mL), while a 25‐mL dose was thereafter provided every 8 days. Muscle biopsies from VL midbelly (MID) and distal myotendinous junction (MTJ) were collected at 0 and 4‐weeks. MPS was then quantified via GC–pyrolysis–IRMS over the 4‐week training period. Expectedly, ECC and CON RET resulted in similar increases in VL muscle thickness (MT) (7.5% vs. 8.4%, respectively) and thigh lean mass (DXA) (2.3% vs. 3%, respectively), albeit through distinct remodeling: Lf increasing more after ECC (5%) versus CON (2%) and PA increasing after CON (7% vs. 3%). MPS did not differ between contractile modes or biopsy sites (MID‐ECC: 1.42 vs. MID‐CON: 1.4% day−1; MTJ‐ECC: 1.38 vs. MTJ‐CON: 1.39% day−1). Muscle thickness at MID site increased similarly following ECC and CON RET, reflecting a tendency for a contractile mode‐independent correlation between MPS and MT (P = 0.07; R2 = 0.18). We conclude that, unlike MT, distinct structural remodeling responses to ECC or CON are not reflected in MPS; the molecular mechanisms of distinct protein deposition, and/or the role of protein breakdown in mediating these responses remain to be defined

    On legitimacy in impact assessment: An epistemologically-based conceptualisation

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    Impact assessment (IA) is carried out as an ex ante process to inform decision-making. It includes requirements for engagement with stakeholders (including the public) regarding actions proposed by a proponent. A key issue with the various stakeholders involved is the perceived legitimacy of the IA, which can have implications both for the reputation of the proponent, and the likelihood of conflict over the decision. But the understanding of legitimacy in the IA literature has changed over time in line with an ontological shift from positivism (that scientifically generated information leads to better informed decisions) to the post-positivist acknowledgement of the limitations of scientific method whereby assumptions must be subject to transparency, deliberation and openness. This has led to an epistemological shift towards greater subjectivism which, we suggest, has created new opportunities (which have been realised in political decision-making) to subvert knowledge through the increased use of the Internet and social media. To address the potential for such subversion of legitimacy, we seek to conceptualise legitimacy in the IA context through framing IA around a critical realist ontology and a reliabilist virtue epistemology. This allows us to identify ‘knowledge legitimacy’ as an equally important component of IA legitimacy along with organisational legitimacy. We conceptualise knowledge legitimacy through literature review drawing on rich understandings of knowledge from IA and other fields of research in order to develop a four-dimensional typology. This includes the dimensions of: knowledge accuracy; knowledge restriction; knowledge diffusion; and knowledge spectrum. This is the first theoretically grounded attempt to understand legitimacy in IA. It is hoped that it will provoke discussion in the IA community to further advance theoretical understandings of IA and legitimacy of practice

    Using Process Evaluation Results to Compare Peer and Adult Leader Delivery of the PAWS (Peer-Education about Weight Steadiness) Club Program

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    To date, there is limited published literature on process evaluation of adolescent health promotion programs. In this paper, we describe the methods and results of PAWS Club process evaluation over 2 years of implementation to compare the effectiveness of delivery by peer and adult leaders. PAWS (Peer-education About Weight Steadiness) Club was a 12-week healthy lifestyle program, delivered to 6th and 7th graders by peer and adult educators, using cluster randomized controlled design. Peer educators were 8th graders in the program schools and adult educators were staff/teachers in the program schools. Trained university students filled out fidelity logs at each session led by peer and adult educators to assess program delivery. The fidelity logs included questions to collect information about the number of participants, duration of the session, percent of activities completed, and if lessons started on time, lesson objectives were clearly stated, lesson objectives were emphasized, demonstrations were visible to participants, all activities were completed, the leader was familiar with lessons, the leader maintained an appropriate pace, the leader kept participants on track, and the leader asked if participants had any questions. Adult educators had a higher mean performance for all questions compared to peer leaders. Significant differences were observed for emphasizing lesson objectives (p = 0.005), making demonstrations visible to participants (p = 0.031), being familiar with the lesson plan (p = 0.000), maintaining an appropriate pace (p = 0.000), keeping participants on track (p = 0.000), and asking if participants had any questions (p = 0.000). Significance was set at p &lt; 0.05. Findings from the current study have implications for designing and conducting a process evaluation of complex healthy lifestyle programs with adolescents in schools. Additional training of peer educators may be needed to enhance program delivery

    Are estimates of food insecurity among college students accurate? Comparison of assessment protocols.

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    A growing body of literature suggests that post-secondary students experience food insecurity (FI) at greater rates than the general population. However, these rates vary dramatically across institutions and studies. FI assessment methods commonly used in studies with college students have not been scrutinized for psychometric properties, and varying protocols may influence resulting FI prevalence estimates. The objective of this study was to assess the performance of standard food security assessment protocols and to evaluate their agreement as well as the relative accuracy of these protocols in identifying student FI. A randomized sample of 4,000 undergraduate students were invited to participate in an online survey (Qualtrics, LLC, Provo, Utah, USA) that evaluated sociodemographic characteristics and FI with the 2-item food sufficiency screener and the 10-item USDA Adult Food Security Survey Module (FSSM; containing the abbreviated 6-item module). Four hundred sixty-two eligible responses were included in the final sample. The psychometric analysis revealed inconsistencies in college student response patterns on the FSSM when compared to national evaluations. Agreement between FI protocols was generally high (>90%) but was lessened when compared with a protocol that incorporated the 2-item screener. The 10-item FSSM with the 2-item screener had the best model fit (McFadden's R2 = 0.15 and Bayesian Information Criterion = -2049.72) and emerged as the tool providing the greatest relative accuracy for identifying students with FI. Though the 10-item FSSM and 2-item screener yields the most accuracy in this sample, it is unknown why students respond to FSSM items differently than the general population. Further qualitative and quantitative evaluations are needed to determine which assessment protocol is the most valid and reliable for use in accurately identifying FI in post-secondary students across the U.S
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