Study Protocol for a Stepped-Wedge Randomized Cookstove Intervention in Rural Honduras: Household Air Pollution and Cardiometabolic Health

Growing evidence links household air pollution exposure from biomass-burning cookstoves to cardiometabolic disease risk. Few randomized controlled interventions of cookstoves (biomass or otherwise) have quantitatively characterized changes in exposure and indicators of cardiometabolic health, a growing and understudied burden in low- and middle-income countries (LMICs). Ideally, the solution is to transition households to clean cooking, such as with electric or liquefied petroleum gas stoves; however, those unable to afford or to access these options will continue to burn biomass for the foreseeable future. Wood-burning cookstove designs such as the Justa (incorporating an engineered combustion zone and chimney) have the potential to substantially reduce air pollution exposures. Previous cookstove intervention studies have been limited by stove types that did not substantially reduce exposures and/or by low cookstove adoption and sustained use, and few studies have incorporated community-engaged approaches to enhance the intervention

Time Course Change of Muscle Thickness of the Tibialis Anterior Following Blood Flow Restricted Training

Traditional resistance training programs recommend training loads of at least 60% 1-repetition maximum (1RM) to stimulate muscle hypertrophy within 3 weeks. Low-load blood flow restricted (BFR) resistance training (RT) has implications in rehabilitation since this modality has shown comparable muscle hypertrophy to high-load RT at intensities as low as 30% 1RM. However, the recommended effects of BFR on muscle size in various musculature throughout an intervention has not been thoroughly examined. PURPOSE: Therefore, the purpose of this investigation is to measure temporal changes in muscle thickness (MT) on the tibialis anterior (TA) throughout 4 weeks of BFR training. METHODS: Thirteen untrained participants were randomized into two groups: (BFR; n=8) (177.6 ± 4.1 cm, 84.8 ± 15.1 kg, 21.3 ± 1 years) or control non-BFR (n=5) (172.6 ± 8.2 cm, 76.7 ± 11.1 kg, 23.4 ± 2.7 years) who were matched for training sessions, sets, and reps. During the 4-week period (8 sessions), participants underwent twice-weekly sessions of unilateral isokinetic dorsiflexion training at 30% of their daily peak torque at a velocity of 60°/s with or without BFR. Ultrasound-derived measures of muscle thickness were captured at one-third the distance from the fibular head to the medial malleolus prior to the pre- and post-intervention testing sessions. Two separate linear regression analyses were used to examine group slope differences in MT across all training sessions. RESULTS: Linear regression analyses indicated that the control (i.e., non-BFR) exhibited a significant, positive (b = 0.023, SE = 0.01, r2=0.626, p=0.006) increase in MT from pre- to post testing. However, there was no significant change (b=0.021, SE = 0.01, r2=0.324, p=0.086) in MT across Time for the BFR group. CONCLUSION: Low-load RT without BFR induces temporal changes in muscle size following a short 4-week intervention. This exemplifies the efficacy of low-load training in inducing detectible changes in muscle thickness of the TA, and does not indicate BFR has an additive effect on temporal changes in muscle size of novice males following a 4-week intervention

Inter- and Intra-Individual Differences in EMG and MMG during Maximal, Bilateral, Dynamic Leg Extensions

The purpose of this study was to compare the composite, inter-individual, and intra-individual differences in the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during fatiguing, maximal, bilateral, and isokinetic leg extension muscle actions. Thirteen recreationally active men (age = 21.7 2.6 years; body mass = 79.8 11.5 kg; height = 174.2 12.7 cm) performed maximal, bilateral leg extensions at 1801 until the torque values dropped to 50% of peak torque for two consecutive repetitions. The EMG and MMG signals from the vastus lateralis (VL) muscles of both limbs were recorded. Four 2(Leg) 19(time) repeated measures ANOVAs were conducted to examine mean differences for EMG AMP, EMG MPF, MMG AMP, and MMG MPF between limbs, and polynomial regression analyses were performed to identify the patterns of neuromuscular responses. The results indicated no significant differences between limbs for EMG AMP (p = 0.44), EMG MPF (p = 0.33), MMG AMP (p = 0.89), or MMG MPF (p = 0.52). Polynomial regression analyses demonstrated substantial inter-individual variability. Inferences made regarding the patterns of neuromuscular responses to fatiguing and bilateral muscle actions should be considered on a subject-by-subject basis

Ipsilateral and Contralateral Torque Responses to Bilateral and Unilateral Maximal, Fatiguing, Isokinetic Leg Extensions

Background: Few studies have compared performance fatigability (PF) for bilateral versus unilateral isokinetic tasks. Objectives: The purpose of this study was to examine: Mode- specific testing responses to isokinetic fatigue, differences in PF between bilateral and unilateral leg extensions, and the effects of fatiguing, unilateral, dynamic leg extensions on contralateral isokinetic peak torque (PT) and maximal voluntary isometric contraction (MVIC). Methods: Eight men (mean ± SD: age= 22.5 ± 2.5 yr.) completed pre- and post-testing for PT and MVIC following 50 bilateral, unilateral right or left leg maximal, isokinetic leg extensions at 180°·s-1, on three separate days. Fatigue-induced decreases in PT and MVIC were used to quantify PF. The data were analyzed with a 4-way repeated measures ANOVA, follow up, and post-hoc analyses. Results: The results indicated that there were no differences (p \u3e 0.05) in PF for the bilateral versus unilateral fatiguing tasks, decreases in PT (p \u3c 0.001 - 0.016; d = 0.54 - 2.58) and MVIC (p \u3c 0.001 - 0.006; η2p = 0.682 - 0.962) for the exercised legs during unilateral fatigue, and a contralateral increase (p = 0.007) in PT following the right leg fatiguing task. Conclusion: The results indicated that PT was more sensitive to fatiguing isokinetic tasks than was MVIC. In addition, there was a facilitation of PT in the contralateral leg following unilateral right leg fatigue. The differences in PT and MVIC testing may be attributable to the timing and/ or relative contributions of peripheral and central fatigue

Cross-Transfer Effects on Muscle Strength, Size, and Quality following Unilateral Blood Flow Restriction Training

Unilateral resistance training (RT) has been shown to induce contralateral strength improvements in the untrained homologous muscle. Notably, low-load blood flow restriction (BFR) RT has shown superior increases in muscle strength and hypertrophy compared to low-load non-BFR RT. Previous literature has also reported that BFR RT has systemic cross-transfer effects of strength on other active skeletal muscles compared to low-load non-BFR RT. PURPOSE: Therefore, the purpose was to examine the cross-transfer effects of 4 weeks of unilateral BFR dorsiflexion RT on muscle strength, hypertrophy, and muscle quality. METHODS: Fourteen untrained participants were randomized into two groups: (BFR; n=8) (177.6 ± 4.1 cm, 84.8 ± 15.1 kg, 21.3 ± 1 years) or control (non-BFR; n=6) (173.2 ± 7.5 cm, 77.9 ± 10.3 kg, 23 ± 2.6 years). Subjects completed 4 weeks (8 sessions) of unilateral isokinetic dorsiflexion RT at 30% of their daily peak torque at a velocity of 60°/s. Isokinetic peak torque, echo intensity (EI), and muscle cross-sectional area (mCSA) were taken bilaterally pre and post RT. Statistical analyses included 3 separate 3-way mixed factorial ANOVAs (Group [BFR, non-BFR] x Time [pre, post] x Leg [right, left]). RESULTS: For isokinetic strength, there were no significant interactions or main effects (p\u3e.05). For EI, there were no significant interactions (p\u3e.05); however, when collapsed across time and leg, there was a significant main effect for group (p=.017; BFR (91.7 ± 1.6 vs. non-BFR (84.8 ± 1.9); mean ± SE). Furthermore, there was no significant interaction for mCSA (p\u3e.05), but there was a significant main effect for time (

Perceptual Fatigability and Neuromuscular Responses During a Sustained, Isometric Forearm Flexion Muscle Action Anchored to a Constant Level of Perceived Exertion

Objective: The purpose of the present study was to examine the fatigue-induced changes in torque, and the electromyographic (EMG) and mechanomyographic (MMG) responses during a sustained submaximal, isometric forearm flexion muscle action anchored to a constant rating of perceived exertion (RPE). Methods: Eleven women (mean ± SD: age = 20.5 ± 1.9 yrs.; height = 169.9 ± 6.6 cm; body mass = 73.2 ± 15.9 kg) performed 2, 3s forearm flexion maximal voluntary isometric contractions (MVIC) before a sustained isometric muscle action anchored to RPE = 7 until task failure (defined as torque that would require RPE \u3e 7, or the torque was reduced to zero). The EMG amplitude (AMP), EMG mean power frequency (MPF), MMG AMP, and MMG MPF signals from the biceps brachii (BB) were recorded. Regression analyses were conducted to examine the torque and neuromuscular responses vs. time relationships. Results: The percent decline in torque during the sustained isometric muscle action was 95.69 ± 6.54 %. There was a significant (p \u3c 0.001; R = -0.998), negative quadratic EMG AMP relationship and a significant (p \u3c 0.046; R = 0.952), positive quadratic MMG AMP relationship vs. Time, but no significant (p \u3e 0.05) relationships for EMG MPF or MMG MPF vs. Time. Conclusion: The findings suggested that torque was initially regulated by an anticipatory feedforward mechanism and continually adjusted due to afferent feedback. In addition, substantial inter-individual, as well as differences between the individual and composite responses, were observed for the neuromuscular response patterns

The Lived Experience of Paradox:How Individuals Navigate Tensions during the Pandemic Crisis

This is a dialogue and part of an article series involving many authors. </p

Genetic determinants of gut microbiota composition and bile acid profiles in mice.

The microbial communities that inhabit the distal gut of humans and other mammals exhibit large inter-individual variation. While host genetics is a known factor that influences gut microbiota composition, the mechanisms underlying this variation remain largely unknown. Bile acids (BAs) are hormones that are produced by the host and chemically modified by gut bacteria. BAs serve as environmental cues and nutrients to microbes, but they can also have antibacterial effects. We hypothesized that host genetic variation in BA metabolism and homeostasis influence gut microbiota composition. To address this, we used the Diversity Outbred (DO) stock, a population of genetically distinct mice derived from eight founder strains. We characterized the fecal microbiota composition and plasma and cecal BA profiles from 400 DO mice maintained on a high-fat high-sucrose diet for ~22 weeks. Using quantitative trait locus (QTL) analysis, we identified several genomic regions associated with variations in both bacterial and BA profiles. Notably, we found overlapping QTL for Turicibacter sp. and plasma cholic acid, which mapped to a locus containing the gene for the ileal bile acid transporter, Slc10a2. Mediation analysis and subsequent follow-up validation experiments suggest that differences in Slc10a2 gene expression associated with the different strains influences levels of both traits and revealed novel interactions between Turicibacter and BAs. This work illustrates how systems genetics can be utilized to generate testable hypotheses and provide insight into host-microbe interactions

Open Science principles for accelerating trait-based science across the Tree of Life.

Synthesizing trait observations and knowledge across the Tree of Life remains a grand challenge for biodiversity science. Species traits are widely used in ecological and evolutionary science, and new data and methods have proliferated rapidly. Yet accessing and integrating disparate data sources remains a considerable challenge, slowing progress toward a global synthesis to integrate trait data across organisms. Trait science needs a vision for achieving global integration across all organisms. Here, we outline how the adoption of key Open Science principles-open data, open source and open methods-is transforming trait science, increasing transparency, democratizing access and accelerating global synthesis. To enhance widespread adoption of these principles, we introduce the Open Traits Network (OTN), a global, decentralized community welcoming all researchers and institutions pursuing the collaborative goal of standardizing and integrating trait data across organisms. We demonstrate how adherence to Open Science principles is key to the OTN community and outline five activities that can accelerate the synthesis of trait data across the Tree of Life, thereby facilitating rapid advances to address scientific inquiries and environmental issues. Lessons learned along the path to a global synthesis of trait data will provide a framework for addressing similarly complex data science and informatics challenges