The effect of core strength on long distance running performance

Training the core has become a topic of interest to athletes, health professionals, coaches and researchers. Core training may be an important supplementation to exercise programs. PURPOSE: The purpose of this study was to determine the effect of an eight week core exercise program on core function and half marathon run time in long distance runners. METHODS: Twenty-four well-trained distance runners were recruited from local running clubs to participate in this training study. Participants ran an average of 20 miles per week and were randomly assigned to the treatment group, receiving core exercises or the control group. McGill\u27s four core tests, the Lafayette Stabilizer Platform and a Pressure Biofeedback Unit were used to measure core function. A simulated half marathon race was conducted to evaluate run time. All tests were performed before and after the eight week intervention. RESULTS: Results showed no significant interaction between core strength and running performance (p\u3c0.05). A 1.76% ± 3.79% reduction in time for the treatment group versus a 0.79% ± 1.66% increase in time for the control group was observed, however, there was no significant main effect of the eight week training program on run time. A significant interaction was observed for the Lafayette Stabilizer Platform (p\u3c0.05), Pressure Biofeedback Unit (p\u3c0.017) and right (p\u3c0.025), group on any of these core function variables. All other variables showed no significant interactions. CONCLUSIONS: The data indicate that eight weeks of core specific training does not result in improved half marathon run time. Core exercises increased strength and stability of the core musculature, however, this increase does not necessarily indicate a subsequent improvement in performance

Nitrogen Cycling Responses to Mountain Pine Beetle Disturbance in a High Elevation Whitebark Pine Ecosystem

Ecological disturbances can significantly affect biogeochemical cycles in terrestrial ecosystems, but the biogeochemical consequences of the extensive mountain pine beetle outbreak in high elevation whitebark pine (WbP) (Pinus albicaulis) ecosystems of western North America have not been previously investigated. Mountain pine beetle attack has driven widespread WbP mortality, which could drive shifts in both the pools and fluxes of nitrogen (N) within these ecosystems. Because N availability can limit forest regrowth, understanding how beetle-induced mortality affects N cycling in WbP stands may be critical to understanding the trajectory of ecosystem recovery. Thus, we measured above- and belowground N pools and fluxes for trees representing three different times since beetle attack, including unattacked trees. Litterfall N inputs were more than ten times higher under recently attacked trees compared to unattacked trees. Soil inorganic N concentrations also increased following beetle attack, potentially driven by a more than two-fold increase in ammonium (NH4+ ) concentrations in the surface soil organic horizon. However, there were no significant differences in mineral soil inorganic N or soil microbial biomass N concentrations between attacked and unattacked trees, implying that short-term changes in N cycling in response to the initial stages of WbP attack were restricted to the organic horizon. Our results suggest that while mountain pine beetle attack drives a pulse of N from the canopy to the forest floor, changes in litterfall quality and quantity do not have profound effects on soil biogeochemical cycling, at least in the short-term. However, continuous observation of these important ecosystems will be crucial to determining the long-term biogeochemical effects of mountain pine beetle outbreaks

Effects of Acute Low-Intensity Cycling on Perceived Stress, Arousal, and Attention

Generally, acute bouts of aerobic exercise have been shown to enhance psychological measures of emotion, mood, and affect. Previous investigations suggest that perceived stress and arousal levels are especially influenced by exercise. Interestingly, very few studies have examined the influence of exercise on attention and whether changes in stress and arousal may augment adaptations in attentional orientation that are often required during exercise. Furthermore, very little is known about the timing of the effects of exercise on these psychological outcomes. PURPOSE: The primary purpose of this study was to examine the effects of low-intensity aerobic exercise on stress, arousal, and attention. A secondary aim was to evaluate the time-course effects of exercise on stress, arousal, and attention. METHODS: Twenty (Mage = 23.2 ± 3.1 years old) college-aged individuals were counterbalanced into low-intensity exercise (LI) and seated control (SC) conditions. During each condition, participants completed a 10-minute resting baseline period, 20 minutes of either sustained cycling or seated rest, and a 20-minute recovery period. Primary outcomes of stress, arousal, and attention were assessed at 10-minute intervals throughout each condition via a Visual Analog Scale for Stress (VAS-S), Felt Arousal Scale (FAS), and Attentional Focus Scale (AFS), respectively. RESULTS: For the VAS-S, a Time main effect was revealed, F(4,16) = 5.76, p = .005, suggesting general reductions in stress following both LI and SC conditions. A Time main effect was also found for the FAS, which was superseded by a Condition x Time interaction, F(4,16) = 3.08, p = .047, indicating a greater increase in arousal levels during the LI condition compared to the SC condition. Lastly, a Time main effect for the AFS was found, F(4,16) = 3.05, p = .049, indicating general shifts from internal to external focus during each condition. CONCLUSION: Taken together, the current results suggest that exercise at lower doses (i.e., low-intensity for 20 minutes) may have minimal influence on more complex psychological perceptions of stress and attention. These results may help us better understand the complicated interactions between common psychological measures used in exercise science research. Additionally, this study may aid in the development of appropriate exercise prescriptions for populations looking to specifically target stress, arousal, and attention

Deciphering the relative roles of matrix metalloproteinase‐ and plasmin‐mediated matrix degradation during capillary morphogenesis using engineered hydrogels

Extracellular matrix (ECM) remodeling is essential for the process of capillary morphogenesis. Here we employed synthetic poly(ethylene glycol) (PEG) hydrogels engineered with proteolytic specificity to either matrix metalloproteinases (MMPs), plasmin, or both to investigate the relative contributions of MMP‐ and plasmin‐mediated ECM remodeling to vessel formation in a 3D‐model of capillary self‐assembly analogous to vasculogenesis. We first demonstrated a role for both MMP‐ and plasmin‐mediated mechanisms of ECM remodeling in an endothelial‐fibroblast co‐culture model of vasculogenesis in fibrin hydrogels using inhibitors of MMPs and plasmin. When this co‐culture model was employed in engineered PEG hydrogels with selective protease sensitivity, we observed robust capillary morphogenesis only in MMP‐sensitive matrices. Fibroblast spreading in plasmin‐selective hydrogels confirmed this difference was due to protease preference by endothelial cells, not due to limitations of the matrix itself. In hydrogels engineered with crosslinks that were dually susceptible to MMPs and plasmin, capillary morphogenesis was unchanged. These findings highlight the critical importance of MMP‐mediated degradation during vasculogenesis and provide strong evidence to justify the preferential selection of MMP‐degradable peptide crosslinkers in synthetic hydrogels used to study vascular morphogenesis and promote vascularization. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2507–2516, 2019.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151850/1/jbmb34341_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151850/2/jbmb34341.pd

Nutrient Acquisition Strategies Augment Growth in Tropical N2‐Fixing Trees in Nutrient‐Poor Soil and Under Elevated CO2

Tropical forests play a dominant role in the global carbon (C) cycle, and models predict increases in tropical net primary productivity (NPP) and C storage in response to rising atmospheric carbon dioxide (CO2) concentrations. The extent to which increasing CO2 will enhance NPP depends in part on the availability of nitrogen (N) and phosphorus (P) to support growth. Some tropical trees can potentially overcome nutrient limitation by acquiring N via symbiotic dinitrogen (N2) fixation, which may provide a benefit in acquiring P via investment in N‐rich phosphatase enzymes or arbuscular mycorrhizal (AM) fungi. We conducted a seedling experiment to investigate the effects of elevated CO2 and soil nutrient availability on the growth of two N2‐fixing and two non‐N2‐fixing tropical tree species. We hypothesized that under elevated CO2 and at low nutrient availability (i.e., low N and P), N2 fixers would have higher growth rates than non‐N2 fixers because N2 fixers have a greater capacity to acquire both N and P. We also hypothesized that differences in growth rates between N2 fixers and non‐N2 fixers would decline as nutrient availability increases because N2 fixers no longer have an advantage in nutrient acquisition. We found that the N2 fixers had higher growth rates than the non‐N2 fixers under elevated CO2 and at low nutrient availability, and that the difference in growth rates between the N2 and non‐N2 fixers declined as nutrient availability increased, irrespective of CO2. Overall, N2 fixation, root phosphatase activity, and AM colonization decreased with increasing nutrient availability, and increased under elevated CO2 at low nutrient availability. Further, AM colonization was positively related to the growth of the non‐N2 fixers, whereas both N2 fixation and root phosphatase activity were positively related to the growth of the N2 fixers. Though our results indicate all four tree species have the capacity to up‐ or down‐regulate nutrient acquisition to meet their stoichiometric demands, the greater capacity for the N2 fixers to acquire both N and P may enable them to overcome nutritional constraints to NPP under elevated CO2, with implications for the response of tropical forests to future environmental change

Remotely Sensed Canopy Nitrogen Correlates With Nitrous Oxide Emissions in a Lowland Tropical Rainforest

Tropical forests exhibit significant heterogeneity in plant functional and chemical traits that may contribute to spatial patterns of key soil biogeochemical processes, such as carbon storage and greenhouse gas emissions. Although tropical forests are the largest ecosystem source of nitrous oxide (N2O), drivers of spatial patterns within forests are poorly resolved. Here, we show that local variation in canopy foliar N, mapped by remote‐sensing image spectroscopy, correlates with patterns of soil N2O emission from a lowland tropical rainforest. We identified ten 0.25 ha plots (assemblages of 40–70 individual trees) in which average remotely‐sensed canopy N fell above or below the regional mean. The plots were located on a single minimally‐dissected terrace (km2) where soil type, vegetation structure and climatic conditions were relatively constant. We measured N2O fluxes monthly for 1 yr and found that high canopy N species assemblages had on average three‐fold higher total mean N2O fluxes than nearby lower canopy N areas. These differences are consistent with strong differences in litter stoichiometry, nitrification rates and soil nitrate concentrations. Canopy N status was also associated with microbial community characteristics: lower canopy N plots had two‐fold greater soil fungal to bacterial ratios and a significantly lower abundance of ammonia‐oxidizing archaea, although genes associated with denitrification (nirS, nirK, nosZ) showed no relationship with N2O flux. Overall, landscape emissions from this ecosystem are at the lowest end of the spectrum reported for tropical forests, consist with multiple metrics indicating that these highly productive forests retain N tightly and have low plant‐available losses. These data point to connections between canopy and soil processes that have largely been overlooked as a driver of denitrification. Defining relationships between remotely‐sensed plant traits and soil processes offers the chance to map these processes at large scales, potentially increasing our ability to predict N2O emissions in heterogeneous landscapes

RNA reference materials with defined viral RNA loads of SARS-CoV-2—A useful tool towards a better PCR assay harmonization

SARS-CoV-2, the cause of COVID-19, requires reliable diagnostic methods to track the circulation of this virus. Following the development of RT-qPCR methods to meet this diagnostic need in January 2020, it became clear from interlaboratory studies that the reported Ct values obtained for the different laboratories showed high variability. Despite this the Ct values were explored as a quantitative cut off to aid clinical decisions based on viral load. Consequently, there was a need to introduce standards to support estimation of SARS-CoV-2 viral load in diagnostic specimens. In a collaborative study, INSTAND established two reference materials (RMs) containing heat-inactivated SARS-CoV-2 with SARS-CoV-2 RNA loads of ~107 copies/mL (RM 1) and ~106 copies/mL (RM 2), respectively. Quantification was performed by RT-qPCR using synthetic SARS-CoV-2 RNA standards and digital PCR. Between November 2020 and February 2021, German laboratories were invited to use the two RMs to anchor their Ct values measured in routine diagnostic specimens, with the Ct values of the two RMs. A total of 305 laboratories in Germany were supplied with RM 1 and RM 2. The laboratories were requested to report their measured Ct values together with details on the PCR method they used to INSTAND. This resultant 1,109 data sets were differentiated by test system and targeted gene region. Our findings demonstrate that an indispensable prerequisite for linking Ct values to SARS-CoV-2 viral loads is that they are treated as being unique to an individual laboratory. For this reason, clinical guidance based on viral loads should not cite Ct values. The RMs described were a suitable tool to determine the specific laboratory Ct for a given viral load. Furthermore, as Ct values can also vary between runs when using the same instrument, such RMs could be used as run controls to ensure reproducibility of the quantitative measurements.Peer Reviewe