Biocultural and social determinants of ill health and early mortality in a New Mexican paediatric autopsy sample.

RESULTS.: Hispanic children have higher odds of growth stunting than non-Hispanic White children. Native American children die younger and have higher odds of respiratory diseases and porous lesions than Hispanic and non-Hispanic Whites. Rural/urban location does not significantly impact age at death, but housing type does. Individuals who lived in trailers/mobile homes had earlier ages at death. When intersections between housing type and housing location are considered, children who were poor and from impoverished areas lived longer than those who were poor from relatively well-off areas. CONCLUSIONS.: Children's health is shaped by factors outside their control. The children included in this study embodied experiences of social and ELS and did not survive to adulthood. They provide the most sobering example of the harm that social factors (structural racism/discrimination, socioeconomic, and political structures) can inflict.

Acute Effects of Sprint Interval Training and Blood Flow Restriction on Neuromuscular and Muscle Function.

BFR) applied during sprint interval training (SIT) on performance and neuromuscular function. METHODS: Fifteen men completed a randomized bout of SIT with CBFR, IBFR, and without BFR (No-BFR), consisting of 2, 30-s maximal sprints on a cycle ergometer with a resistance of 7.5% of body mass. Concentric peak torque (CPT), maximal voluntary isometric contraction (MVIC) torque, and muscle thickness (MT) were measured before and after SIT, including surface electromyography (sEMG) recorded during the strength assessments. Peak and mean revolutions per minute (RPM) were measured during SIT and power output was examined relative to physical working capacity at the fatigue threshold (PWCFT). RESULTS: CPT and MVIC torque decreased from pre-SIT (220.3±47.6 Nm and 355.1±72.5 Nm, respectively) to post-SIT (147.9±27.7 Nm and 252.2±45.5 Nm, respectively, all P<0.05), while MT increased (1.77±0.31 cm to 1.96±0.30 cm). sEMG mean power frequency decreased during CPT (-12.8±10.5%) and MVIC (-8.7±10.2%) muscle actions. %PWCFT was greater during No-BFR (414.2±121.9%) than CBFR (375.9±121.9%). CONCLUSION: SIT with or without BFR induced comparable alterations in neuromuscular fatigue and sprint performance across all conditions, without affecting neuromuscular function.

Blood flow restriction attenuates surface mechanomyography lateral and longitudinal, but not transverse oscillations during fatiguing exercise.

Objective. Surface mechanomyography (sMMG) can measure oscillations of the activated muscle fibers in three axes (i.e.X,Y, andZ-axes) and has been used to describe motor unit activation patterns (X-axis). The application of blood flow restriction (BFR) is common in exercise studies, but the cuff may restrict muscle fiber oscillations. Therefore, the purpose of this investigation was to examine the acute effects of submaximal, fatiguing exercise with and without BFR on sMMG amplitude in theX,Y, andZ-axes among female participants.Approach. Sixteen females (21 ± 1 years) performed two separate exercise bouts to volitional exhaustion that consisted of unilateral, submaximal (50% maximal voluntary isometric contraction [MVIC]) intermittent, isometric, leg extensions with and without BFR. sMMG was recorded and examined across percent time to exhaustion (%TTE) in 20% increments. Separate 2-way repeated measures ANOVA models were constructed: (condition [BFR, non-BFR]) × (time [20, 40, 60, 80, and 100% TTE]) to examine absolute (m·s-2) and normalized (% of pretest MVIC) sMMG amplitude in theX-(sMMG-X),Y-(sMMG-Y), andZ-(sMMG-Z) axes.Main results. The absolute sMMG-X amplitude responses were attenuated with the application of BFR (mean ± SD = 0.236 ± 0.138 m·s-2) relative to non-BFR (0.366 ± 0.199 m·s-2, collapsed across time) and for sMMG-Y amplitude at 60%-100% of TTE (BFR range = 0.213-0.232 m·s-2versus non-BFR = 0.313-0.445 m·s-2). Normalizing sMMG to pretest MVIC removed most, but not all the attenuation which was still evident for sMMG-Y amplitude at 100% of TTE between BFR (72.9 ± 47.2%) and non-BFR (98.9 ± 53.1%). Interestingly, sMMG-Z amplitude was not affected by the application of BFR and progressively decreased across %TTE (0.332 ± 0.167 m·s-2to 0.219 ± 0.104 m·s-2, collapsed across condition.)Significance. The application of BFR attenuated sMMG-X and sMMG-Y amplitude, although normalizing sMMG removed most of this attenuation. Unlike theXandY-axes, sMMG-Z amplitude was not affected by BFR and progressively decreased across each exercise bout potentially tracking the development of muscle fatigue.

Blood flow restriction increases necessary muscle excitation of the elbow flexors during a single high-load contraction.

PURPOSE: To investigate the effects of blood flow restriction (BFR) on electromyographic amplitude (EMGRMS)-force relationships of the biceps brachii (BB) during a single high-load muscle action. METHODS: Twelve recreationally active males and eleven recreationally active females performed maximal voluntary contractions (MVCs), followed by an isometric trapezoidal muscle action of the elbow flexors at 70% MVC. Surface EMG was recorded from the BB during BFR and control (CON) visits. For BFR, cuff pressure was 60% of the pressure required to completely occlude blood at rest. Individual b (slope) and a terms (gain) were calculated from the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments of the trapezoid. EMGRMS during the steady force segment was normalized to MVC EMGRMS. RESULTS: For BFR, the b terms were greater during the linearly increasing segment than the linearly decreasing segment (p < 0.001), and compared to the linearly increasing segment for CON (p < 0.001). The a terms for BFR were greater during the linearly decreasing than linearly increasing segment (p = 0.028). Steady force N-EMGRMS was greater for BFR than CON collapsed across sex (p = 0.041). CONCLUSION: BFR likely elicited additional recruitment of higher threshold motor units during the linearly increasing- and steady force-segment. The differences between activation and deactivation strategies were only observed with BFR, such as the b terms decreased and the a terms increased for the linearly decreasing segment in comparison to the increasing segment. However, EMGRMS-force relationships during the linearly increasing- and decreasing-segments were not different between sexes during BFR and CON.

Innovations in the Assessment of Skeletal Muscle Health: A Glimpse into the Future.

Skeletal muscle is the largest organ system in the human body and plays critical roles in athletic performance, mobility, and disease pathogenesis. Despite growing recognition of its importance by major health organizations, significant knowledge gaps remain regarding skeletal muscle health and its crosstalk with nearly every physiological system. Relevant public health challenges like pain, injury, obesity, and sarcopenia underscore the need to accurately assess skeletal muscle health and function. Feasible, non-invasive techniques that reliably evaluate metrics including muscle pain, dynamic structure, contractility, circulatory function, body composition, and emerging biomarkers are imperative to unraveling the complexities of skeletal muscle. Our concise review highlights innovative or overlooked approaches for comprehensively assessing skeletal muscle in vivo. We summarize recent advances in leveraging dynamic ultrasound imaging, muscle echogenicity, tensiomyography, blood flow restriction protocols, molecular techniques, body composition, and pain assessments to gain novel insight into muscle physiology from cellular to whole-body perspectives. Continued development of precise, non-invasive tools to investigate skeletal muscle are critical in informing impactful discoveries in exercise and rehabilitation science.

Sex differences in muscle contraction-induced limb blood flow limitations.

PURPOSE: To determined sex differences in absolute- and %-reductions in blood flow during intermittent muscular contractions as well as relationships between blood flow reductions and time to task failure (TTF). METHODS: Thirteen males (25 ± 4 years) and 13 females (22 ± 5 years) completed intermittent isometric trapezoidal forearm flexion at 50% maximal voluntary contraction until task failure. Doppler ultrasound was used to measure brachial artery blood flow (BABF) during the 12-s plateau phase and 12-s relaxation phase. RESULTS: Target torque was less in females than males (24 ± 5 vs. 42 ± 7 Nm; p < 0.001); however, TTF was not different between sexes (F: 425 ± 187 vs. M: 401 ± 158 s; p = 0.72). Relaxation-phase BABF at end-exercise was less in females than males (435 ± 161 vs. 937 ± 281 mL/min; p < 0.001) but contraction-phase BABF was not different (127 ± 46 vs. 190 ± 99 mL/min; p = 0.42). Absolute- and %-reductions in BABF by contraction were less in females than males (309 ± 146 vs. 747 ± 210 mL/min and 69 ± 10 vs. 80% ± 6%, respectively; both p < 0.01) and were associated with target torque independent of sex (r = 0.78 and 0.56, respectively; both p < 0.01). Absolute BABF reduction per target torque (mL/min/Nm) and TTF were positively associated in males (r = 0.60; p = 0.031) but negatively associated in females (r = - 0.61; p = 0.029). CONCLUSIONS: This study provides evidence that females incur less proportional reduction in limb blood flow from muscular contraction than males at a matched relative intensity suggesting females may maintain higher levels of muscle oxygen delivery and metabolite removal than males across the contraction-relaxation cycle of intermittent exercise.

Bridging Place-Based Astrobiology Education with Genomics, Including Descriptions of Three Novel Bacterial Species Isolated from Mars Analog Sites of Cultural Relevance.

Democratizing genomic data science, including bioinformatics, can diversify the STEM workforce and may, in turn, bring new perspectives into the space sciences. In this respect, the development of education and research programs that bridge genome science with "place" and world-views specific to a given region are valuable for Indigenous students and educators. Through a multi-institutional collaboration, we developed an ongoing education program and model that includes Illumina and Oxford Nanopore sequencing, free bioinformatic platforms, and teacher training workshops to address our research and education goals through a place-based science education lens. High school students and researchers cultivated, sequenced, assembled, and annotated the genomes of 13 bacteria from Mars analog sites with cultural relevance, 10 of which were novel species. Students, teachers, and community members assisted with the discovery of new, potentially chemolithotrophic bacteria relevant to astrobiology. This joint education-research program also led to the discovery of species from Mars analog sites capable of producing N-acyl homoserine lactones, which are quorum-sensing molecules used in bacterial communication. Whole genome sequencing was completed in high school classrooms, and connected students to funded space research, increased research output, and provided culturally relevant, place-based science education, with participants naming three novel species described here. Students at St. Andrew's School (Honolulu, Hawai'i) proposed the name Bradyrhizobium prioritasuperba for the type strain, BL16AT, of the new species (DSM 112479T = NCTC 14602T). The nonprofit organization Kauluakalana proposed the name Brenneria ulupoensis for the type strain, K61T, of the new species (DSM 116657T = LMG = 33184T), and Hawai'i Baptist Academy students proposed the name Paraflavitalea speifideiaquila for the type strain, BL16ET, of the new species (DSM 112478T = NCTC 14603T).

Influence of Body Composition, Load-Velocity Profiles, and Sex-Related Differences on Army Combat Fitness Test Performance.

ABSTRACT: Boffey, D, DiPrima, JA, Kendall, KL, Hill, EC, Stout, JR, and Fukuda, DH. Influence of body composition, load-velocity profiles, and sex-related differences on army combat fitness test performance. J Strength Cond Res 37(12): 2467-2476, 2023-The Army Combat Fitness Test (ACFT) became the U.S. Army's mandatory physical fitness test in April of 2022. The purpose of this study was to determine the relationship between ACFT performance and both body composition and velocity profiles and to determine sex differences for these variables. Data were collected at 2 timepoints 4 months apart, from male (n = 55) and female (n = 17) Army Reserve Officers' Training Corps (ROTC) cadets. Body composition was assessed with a bioelectrical impedance spectroscopy device, and cadets completed a hex bar deadlift load-velocity profile (LVP) and ACFT on separate days. Stepwise multiple regressions were used to explain the amount of variance in ACFT total score and individual event performance. Significance for statistical tests was defined as an alpha level of p ≤ 0.05. Muscle mass and body fat percentage accounted for 49% of shared variance of total ACFT score, and deadlift maximal power and maximal velocity accounted for 67% of shared variance of total ACFT score. The 3 repetition maximum deadlift, standing power throw, hand-release push-up, and sprint-drag-carry events favored cadets with more muscle mass, whereas the leg tuck was influenced by the body fat percentage and the 2-mile run was affected by fat mass. Sex had greater predictive capability for the 2-mile run than body composition. Men outperformed women on all individual events, with the greatest differences on standing power throw and sprint-drag-carry. It is recommended that Army ROTC cadets taking the ACFT maximize lower-body power production and increase muscle mass.

Testing Geology with Biology: Plate Tectonics and the Diversification of Microhylid Frogs in the Papuan Region.

Studies of the Papuan region have provided fundamental insights into the evolutionary processes generating its exceptional biodiversity, but the influence of geological processes merits further study. Lying at the junction of five tectonic plates, this region has experienced a turbulent geological history that has not only produced towering mountains allowing elevational specialization and island archipelagos with varying degrees of isolation promoting vicariance, but also active margins where land masses have collided and been subsequently rifted apart creating a mosaic of intermixed terranes with vastly different geological histories. Asterophryine frogs are a hyperdiverse clade representing half the world's microhylid diversity (over 360 species) centered on New Guinea and its satellite islands. We show that vicariance facilitated by geological history explains this far and wide distribution of a clade that should have poor dispersal abilities. We recovered a mainland tectonic unit, the East Papua Composite Terrane (EPCT), as the center of origin for Asterophryinae and no fewer than 71 instances of what appear to be long-distance dispersal events, 29 of which are between mainland regions, with 42 from the mainland to the islands, some presently as far as 200 km away from source populations over open ocean. Furthermore, we find strong support for a "Slow and Steady" hypothesis for the formation of the northern margin of New Guinea by many separate accretion events during the Miocene, over other major geological alternatives, consistent with the 20 M year age of the clade and arrival via the EPCT. In addition, the historical biogeography of our frogs strongly supports an affiliation of the Louisiade Archipelago and Woodlark Island with the Owen Stanley Range on the EPCT, and the recent proximity of the large New Britain Island. Our results show that Asterophryinae did not have to repeatedly and independently disperse across large ocean barriers to the offshore islands, against the predictions of island biogeography theory, but that the current distribution can be explained through vicariance and short-distance oceanic dispersal as historical land connections disappeared and islands slowly became separated from each other. We show that islands have a life history, changing in distance from other land masses, with consequent opportunities for dispersal, isolation, and cladogenesis of their biotas. More broadly, we can begin to see how the geological history of the Papuan region can result in the rapid accumulation and staggering number of extant species.

Time of Day Effects on Anaerobic Performance Using a Nonmotorized Treadmill.

ABSTRACT: Renziehausen, JM, Bergquist, AM, Park, J-H, Hill, EC, Wells, AJ, Stout, JR, and Fukuda, DH. Time of day effects on anaerobic performance using a nonmotorized treadmill. J Strength Cond Res 37(10): 2002-2007, 2023-The purpose of this study was to determine the effects of time of day on performance during a maximal effort sprinting assessment (30nmt) and determine potential differences based on chronotype and sex. Twenty-six recreationally active men (n = 12) and women (n = 14) between the ages of 18 and 35 years old (21.5 ± 2.4 years) completed the 30nmt at 9:00 am, 2:00 pm, and 7:00 pm in a randomized order over a 24-hour period. Resting heart rate and temperature assessments were taken at each visit. A dietary recall and the Morningness-Eveningness Questionnaire were used to assess kilocalories (kcals) and chronotype, respectively. Two-way (time x sex) repeated measures analyses of variance were conducted to determine differences in peak/mean power, peak/mean velocity, distance, resting heart rate, temperature, and kcals at each time point. Paired sample t tests were used to assess peak and nadir of each performance variable. A significance level was set at p < 0.05. There was a significant main effect for temperature (p < 0.001), resting heart rate (p = 0.007), and pre-exercise caloric intake (p = 0.021) throughout the day. No significant main effects for time were found for peak power (p = 0.766), mean power (p = 0.094), peak velocity (p = 0.497), mean velocity (p = 0.193), or distance (p = 0.262). There were no significant time × sex interactions for any dependent performance variables (p > 0.05). Significant differences were shown between the peak and nadir of each performance variable (p < 0.001). There were no significant differences in performance during maximal effort anaerobic assessments shown throughout the day; however, peak/nadir of performance times may be individualized and differ between morning types and intermediate types.

Acute Effects of Continuous and Intermittent Blood Flow Restriction on Sprint Interval Performance and Muscle Oxygen Responses.

ABSTRACT: Wizenberg, AM, Gonzalez-Rojas, D, Rivera, PM, Proppe, CE, Laurel, KP, Stout, JR, Fukuda, DH, Billaut, F, Keller, JL, and Hill, EC. Acute effects of continuous and intermittent blood flow restriction on sprint interval performance and muscle oxygen responses. J Strength Cond Res 37(10): e546-e554, 2023-This investigation aimed to examine the acute effects of continuous and intermittent blood flow restriction (CBFR and IBFR, respectively) during sprint interval training (SIT) on muscle oxygenation, sprint performance, and ratings of perceived exertion (RPE). Fifteen men (22.6 ± 2.4 years; 176 ± 6.3 cm; 80.0 ± 12.6 kg) completed in random order a SIT session with CBFR, IBFR (applied during rest), and no blood flow restriction (NoBFR). Each SIT session consisted of two 30-second all-out sprint tests separated by 2 minutes. Peak power (PP), total work (TW), sprint decrement score (S dec ), RPE, and muscle oxygenation were measured during each sprint. A p value ≤0.05 was considered statistically significant. PP decreased to a greater extent from sprint 1 to sprint 2 during CBFR (25.5 ± 11.9%) and IBFR (23.4 ± 9.3%) compared with NoBFR (13.4 ± 8.6%). TW was reduced similarly (17,835.6 ± 966.2 to 12,687.2 ± 675.2 J) from sprint 1 to sprint 2 for all 3 conditions, but TW was lower (collapsed across time) for CBFR (14,320.7 ± 769.1 J) than IBFR (15,548.0 ± 840.5 J) and NoBFR (15,915.4 ± 771.5 J). There were no differences in S dec (84.3 ± 1.7%, 86.1 ± 1.5%, and 87.2 ± 1.1% for CBFR, IBFR, and NoBFR, respectively) or RPE, which increased from sprint 1 (8.5 ± 0.3) to sprint 2 (9.7 ± 0.1). Collective muscle oxygenation responses increased across time and were similar among conditions, whereas increases in deoxy[heme] and total[heme] were greatest for CBFR. Applying BFR during SIT induced greater decrements in PP, and CBFR resulted in greater decrements in work across repeated sprints. The larger increases in deoxy[heme] and total[heme] for CBFR suggested it may induce greater metabolite accumulation than IBFR and NoBFR when combined with SIT.

Acute effects of low load blood flow restricted and non restricted exercise on muscle excitation, neuromuscular efficiency, and average torque.

OBJECTIVES: The purpose of this investigation was to examine the acute effects of low-load blood flow restriction (LLBFR) and low-load (LL) resistance exercise on muscle excitation, neuromuscular efficiency, and average torque. METHODS: Eleven men (age±SD=22±3yrs) randomly performed LLBFR and LL that consisted of 30 unilateral leg extensions at 30% of one-repetition maximum while surface electromyography (sEMG) and torque were simultaneously assessed. Polynomial regression analyses and slope comparisons were performed to examine patterns of responses and rates of change. RESULTS: sEMG amplitude increased for LLBFR (9 of 11) and LL (8 of 11) and between composite responses (R2=0.939-0.981). For LLBFR, sEMG amplitude increased to a greater extent for 5 of the 11 individual and for the composite responses. Similarly, neuromuscular efficiency decreased for LLBFR (8 of 11) and LL (5 of 11) as well as the composite responses r2=0.902-0.929, but the decrease was larger for LLBFR than LL for the individual (4 of 11) responses. For average submaximal concentric torque, there were individual increases, decreases, and no changes for the composite responses (R2=0.198-0.325). CONCLUSION: LLBFR elicited greater fatigue-induced increases in muscle excitation and decreases in neuromuscular efficiency than LL, but neither LLBFR nor LL affected average submaximal concentric torque.

Sex differences in NIRS-derived values of reactive hyperemia persist after experimentally controlling for the ischemic vasodilatory stimulus.

Men and women exhibit different near-infrared spectroscopy (NIRS) outcomes in response to vascular occlusion tests (VOT), which may be due to phenotypic characteristics or different degrees of desaturation during ischemia. The minimum skeletal muscle tissue oxygenation (StO2min) observed during a VOT may be the primary determinant of reactive hyperemic (RH) responses. Our purpose was to determine the contribution StO2min and participant characteristics including adipose tissue thickness (ATT), lean body mass (LBM), muscular strength, and limb circumference to NIRS-derived indexes of RH. Also, we aimed to determine if matching StO2min would eliminate NIRS-VOT sex differences. Thirty-one young adults completed one or two VOTs during which the vastus lateralis was continuously assessed for StO2. The men and women each completed a standard VOT with a 5-min ischemic phase. The men completed a second VOT with a shortened ischemic phase to produce a matching StO2min to the minimum of the women observed during the standard VOT. Mean sex differences were determined with t tests, and relative contributions were assessed with multiple regression and model comparison approaches. During the 5-min ischemic phase, the men exhibited greater upslopes (1.97 ± 0.66 vs. 1.23 ± 0.59%·s-1) and greater StO2max than the women (80.3 ± 4.17 vs. 76.2 ± 2.86%). Analysis revealed StO2min was a greater contributor to upslope than sex and/or ATT. For StO2max, sex was the only significant predictor (r2 = 0.26, men ∼4.09% > women). Experimentally matching StO2min did not eliminate the sex differences in upslope or StO2max, suggesting that characteristics other than the degree of desaturation primarily provoke sex differences in RH.NEW & NOTEWORTHY Men exhibit greater values of reactive hyperemia than women even when controlling for the magnitude of desaturation during transient ischemia. Factors other than the ischemic vasodilatory stimulus, such as skeletal muscle mass and quality, likely provoke the commonly reported sex differences in reactive hyperemia measured by near-infrared spectroscopy.

Low bone mineral density is associated with fatty liver disease and respiratory illness in a pediatric mortality sample.

This study finds that fatty liver disease is associated with low bone density in a pediatric mortality sample. Since non-alcoholic fatty liver disease has increased in prevalence over the past few decades among children, a better understanding of the disease's impacts on bone health is of significance to clinicians. PURPOSE: Chronic illness leads to decreased bone modeling and remodeling. This can be especially problematic during childhood and adolescence, since the majority of an individual's peak bone mass is achieved by the age of 20. In this study, we examine relationships between chronic illness and low bone mineral density (BMD) in a pediatric mortality sample (aged 0.5 to 20.9 years) from New Mexico. We also test whether low BMD is related to decelerated linear growth by examining its relationship to growth stunting and arrest (Harris lines). METHODS: Hounsfield units (HU), a proxy for trabecular BMD, were obtained at the fourth lumbar vertebra and the femoral neck from postmortem CT scans. Linear regression was used to examine associations between z-standardized HU and age, sex, medical conditions, Harris lines, and growth stunting. RESULTS: We find that lumbar HU is significantly lower for individuals with fatty liver disease and respiratory illness; femoral HU is significantly lower in individuals with Harris lines. CONCLUSION: The mechanisms of low BMD in individuals with fatty liver disease and respiratory illness are likely multifactorial and involve vitamin D deficiency (malnutrition, malabsorption), systemic inflammation, and sedentary lifestyles. However, better awareness of this relationship can provide clinicians with the ability to introduce nutritional and behavioral interventions early to mitigate deleterious effects on bone. Harris lines, on the other hand, mark temporary growth cessation due to physiological stress followed by a rapid resumption of growth. Low BMD in these individuals may be due to bone mineralization lagging behind relatively rapid linear growth.

Neuromuscular Responses to Failure vs Non-Failure During Blood Flow Restriction Training in Untrained Females.

Applying blood flow restriction (BFR) during resistance exercise is a potent stimulus of muscular adaption, but there is little direct comparison of its effect on neuromuscular function. The purpose of this investigation was to compare surface electromyography amplitude and frequency responses during a 75 (1 × 30, 3 × 15) repetition bout (BFR-75) of BFR to 4 sets to failure (BFR-F). Twelve women (mean ± SD age = 22 ± 4 years; body mass = 72 ± 14.4 kg; height = 162.1 ± 4.0 cm) volunteered for the investigation. One leg was randomly assigned to complete BFR-75 and the other to BFR-F. Each leg performed isokinetic, unilateral, concentric-eccentric, leg extension at 30% of maximal strength while surface electromyographic (sEMG) data was recorded. More repetitions (p = 0.006) were completed during set 2 for BFR-F (21.2 ± 7.4) than BFR-75 (14.7 ± 1.2), but there were no other between condition differences for set 1 (29.8 ± 0.9 vs 28.9 ± 10.1), set 3 (14.4 ± 1.4 vs 17.1 ± 6.9), or set 4 (14.8 ± 0.9 vs 16.3 ± 7.0). Collapsed across condition, normalized sEMG amplitude increased (p = 0.014, 132.66 ± 14.03% to 208.21 ± 24.82%) across the first three sets of exercise then plateaued, while normalized sEMG frequency decreased (p = 0.342, 103.07 ± 3.89% to 83.73 ± 4.47%) across the first two sets then plateaued. The present findings indicated that BFR-75 and BFR-F elicited similar acute neuromuscular fatigue responses. The plateau in amplitude and frequency suggested that maximal motor unit excitation and metabolic buildup may be maximized after two to three sets of BFR-75 and BFR-F.

75-repetition versus sets to failure of blood flow restriction exercise on indices of muscle damage in women.

ABSTRACTThere is conflicting evidence regarding the prevalence and magnitude of exercise-induced muscle damage (EIMD) following low-load resistance exercise with blood flow restriction (LL + BFR) that may be related to exercise protocols. The purpose of this investigation was to examine the effects of 75-repetition (BFR-75) (1 × 30, 3 × 15) and 4 sets to failure (BFR-4x) protocols on indices of EIMD among untrained women. Thirteen women completed this investigation. One leg was randomly assigned to BFR-75 and the other to BFR-4x. Each leg performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% of maximal strength. Indices of EIMD (muscle soreness, range of motion [ROM], limb circumference, pain pressure threshold [PPT], and maximal voluntary isometric contraction [MVIC]) were recorded before exercise, 0-, 24-, 48-, 72-, and 96-hours post-exercise. There were no changes for ROM, circumference, or PPT. Muscle soreness increased similarly in both conditions 0-, 24-, and 48-hours post-exercise and MVIC increased 24-, 48-, 72-, and 96-hours post-exercise. These findings suggested BFR-75 and BFR-4x were not associated with EIMD and elicited similar physiological responses. The increases in muscle soreness may be due to metabolic stress associated with LL + BFR protocols apart from EIMD.

HighlightsThere was no evidence of significant exercise-induced muscle damage following low-load resistance exercise with blood flow restriction completed failure and non-failure.Muscle function was not impaired 24-96 h post-exercise for either protocol.Low-load resistance exercise with blood flow restriction using a 75-repetition and 4 sets to volitional failure protocol resulted in similar physiological responses to exercise.There may be higher levels of metabolic stress which may increase muscle soreness following low-load resistance exercise with blood flow restriction.

Molecular and phylogenetic datasets for the Asterophryinae frogs of New Guinea with additional data on lifestyle, geography, and elevation.

The data provided here are related to the article "Resolving the Deep Phylogeny: Implications for Early Adaptive Radiation, Cryptic, and Present-day Ecological Diversity of Papuan Microhylid Frogs" [1]. The dataset is based on 233 tissue samples of the subfamily Asteroprhyinae, with representatives from all recognized genera, in addition to three outgroup taxa. The sequence dataset contains over 2400 characters per sample for five genes: three nuclear (Seventh in Absentia (SIA), Brain Derived Neurotrophic Factor (BDNF), Sodium Calcium Exchange subunit-1 (NXC-1)), and two mitochondrial loci (Cytochrome oxidase b (CYTB), and NADH dehydrogenase subunit 4 (ND4)); and is 99% complete. New primers were designed for all loci and accession numbers for the raw sequence data are provided. The sequences are used with geological time calibrations to produce time-calibrated Bayesian inference (BI) and Maximum Likelihood (ML) phylogenetic reconstructions using BEAST2 and IQ-TREE. Lifestyle data (arboreal, scansorial, terrestrial, fossorial, semi-aquatic) were collected from the literature and field notes and used to infer ancestral character states for each lineage. Collection location and elevation data were used to verify sites where multiple species or candidate species co-occur. All sequence data, alignments, and associated metadata (voucher specimen number, species identification, type locality status, global positioning system [GPS] coordinates, elevation, site with species list, and lifestyle) as well as the code to produce all analyses and figures are provided.

Skeletal manifestations of disease experience: Length of illness and porous cranial lesion formation in a contemporary juvenile mortality sample.

OBJECTIVES: Porous lesions of the orbit (cribra orbitalia [CO]) and cranial vault (porotic hyperostosis [PH]) are used as skeletal indicators of childhood stress. Because they are understudied in contemporary populations, their relationship to disease experience is poorly understood. This paper examines the relationship between length of childhood illness and CO/PH formation in a clinically documented sample. "Turning points," which identify the window for lesion formation for CO/PH, are defined, implications for hidden heterogeneity in frailty are considered. METHODS: Data are from 333 (199 males; 134 females) pediatric postmortem computed tomography scans. Individuals died in New Mexico (2011-2019) and are 0.5 to 15.99 years (mean = 7.1). Length of illness was estimated using information from autopsy and field reports. Logistic regression was used to estimate predicted probabilities, odds ratios, and the temporal window for lesion formation. RESULTS: Illness, single bouts, or cumulative episodes lasting over 1 month is associated with higher odds of CO; individuals who were never sick have lower odds of having PH. This relationship was consistent for fatal and incidental illnesses that did not cause death. The developmental window for CO formation appears to close at 8 years. CONCLUSIONS: Those ill for over 1 month are more likely to have CO/PH than those with acute illnesses. Some individuals lived sufficiently long to form CO/PH but died of illness. Others with lesions died of circumstances unrelated to disease. This indicates hidden variation in robusticity even among ill individuals with CO/PH, which is vital in interpreting lesion frequencies in the archeological record.

Perinatal Disorders and Small Birthweight Are Significantly Associated With Small Vertebral Neural Canal Size in a Contemporary Pediatric Autopsy Sample.

STUDY DESIGN: A retrospective, nonblinded, single-center observational study. OBJECTIVE: The purpose of this study is to examine associations between small vertebral neural canal (VNC) measurements with verified experiences of early-life stress (ELS) (premature birth, disorders or conditions arising in the perinatal period, and congenital disorders) in a pediatric autopsy sample, paired with other skeletal indicators of stress, and known demographic/health information. SUMMARY OF BACKGROUND DATA: Most studies linking small VNC size to ELS are for human remains from archeological sites without known demographic information or health history, making it difficult to assess what kind of stress might affect VNC growth. METHODS: This is a single-center retrospective study in a pediatric autopsy sample of 623 individuals (aged 0.5 to 20.9 yr) with known sex, age, and manner of death (MOD), who died between 2011 and 2019. Data were collected from postmortem computed tomography scans, autopsy, and field investigator reports. Data include VNC anteroposterior and transverse (TR) diameters of the 12th thoracic (T12) and fifth lumbar (L5) vertebrae, bone mineral density, and Harris lines. RESULTS: Small birthweight males have significantly smaller VNC than those with an average birthweight. The natural MOD is associated with smaller VNC. Perinatal disorders and growth stunting are associated with smaller T12 anteroposterior, T12-TR, and L5-TR diameters. Congenital disorders and Harris lines are not associated with small VNC. CONCLUSIONS: Reduced VNC size is a reliable indicator of severe ELS, but not all ELS leads to reduced VNC. Females appear less susceptible to perinatal environmental stress than males. Reduced VNC may also be indicative of heightened risk of disease and death in those who died of natural MOD. LEVEL OF EVIDENCE: Level 2.

Effects of load matched isokinetic versus isotonic blood flow restricted exercise on neuromuscular and muscle function.

The purpose of this investigation was to examine neuromuscular function, muscle fatigue, rating of perceived exertion (RPE), and muscle swelling between isokinetic and isotonic leg extensions with blood flow restriction (BFR). Fourteen (21 ± 2years; 160cm ± 3.8; 61kg ± 9.1) trained women performed 75 (1 × 30,3 × 15) submaximal (30% of maximal strength), unilateral, isokinetic and isotonic leg extensions with BFR (60% of total arterial occlusion pressure). Before and after exercise, subjects performed maximal voluntary isometric contractions (MVIC) and muscle thickness (MT) was assessed with ultrasound. RPE was recorded across all sets and surface electromyography (EMG) was assessed during the MVIC muscle actions. Separate repeated measures ANOVAs were used to examine MVIC, MT, RPE and neuromuscular function. There were greater reductions in MVIC torque and EMG mean power frequency following isotonic (46.2 ± 17.1%; 16.4 ± 7.9%) than isokinetic (17.9 ± 10.9%;6.5 ± 6.3%). RPE was also higher during isotonic (7.5 ± 2.2), than isokinetic (5.7 ± 1.9). There were no differences in EMG amplitude or MT increases (20 ± 2.1%) between conditions. Isotonic BFR elicited greater fatigue-induced decreases in muscular strength and greater RPE than isokinetic BFR, but similar MT and muscle excitation responses for both conditions. Therefore, both isokinetic and isotonic may induce similar acute physiological responses, but isotonic BFR was associated with greater muscle fatigue and perceived effort.HighlightsExercise modality affects the fatigue and perceptual responses when applying blood flow restriction.Despite greater utility, isotonic blood flow restriction was associated greater fatigue and perceived effort.Isotonic and isokinetic blood flow restriction elicited comparable neural changes.