Climate-driven spatial and temporal patterns in peatland pool biogeochemistry

Peatland pools are freshwater bodies that are highly dynamic aquatic ecosystems because of their small size and their development in organic-rich sediments. However, our ability to understand and predict their contribution to both local and global biogeochemical cycles under rapidly occurring environmental change is limited because the spatiotemporal drivers of their biogeochemical patterns and processes are poorly understood. We used (1) pool biogeochemical data from 20 peatlands in eastern Canada, the United Kingdom, and southern Patagonia and (2) multi-year data from an undisturbed peatland of eastern Canada, to determine how climate and terrain features drive the production, delivering and processing of carbon (C), nitrogen (N), and phosphorus (P) in peatland pools. Across sites, climate (24%) and terrain (13%) explained distinct portions of the variation in pool biogeochemistry, with climate driving spatial differences in pool dissolved organic C (DOC) concentration and aromaticity. Within the multi-year dataset, DOC, carbon dioxide (CO2 ), total N concentrations, and DOC aromaticity were highest in the shallowest pools and at the end of the growing seasons, and increased gradually from 2016 to 2021 in relation to a combination of increases in summer precipitation, mean air temperature for the previous fall, and number of extreme summer heat days. Given the contrasting effects of terrain and climate, broad-scale terrain characteristics may offer a baseline for the prediction of small-scale pool biogeochemistry, while broad-scale climate gradients and relatively small year-to-year variations in local climate induce a noticeable response in pool biogeochemistry. These findings emphasize the reactivity of peatland pools to both local and global environmental change and highlight their potential to act as widely distributed climate sentinels within historically relatively stable peatland ecosystems.

Biological Invasions Affect Resource Processing in Aquatic Ecosystems: The Invasive Amphipod Dikerogammarus villosus Impacts Detritus Processing through High Abundance Rather than Differential Response to Temperature

Anthropogenic stressors such as climate warming and invasive species and natural stressors such as parasites exert pressures that can interact to impact the function of ecosystems. This study investigated how these stressors interact to impact the vital ecosystem process of shredding by keystone species in temperate freshwater ecosystems. We compared metabolic rates and rates of shredding at a range of temperatures up to extreme levels, from 5 °C to 30 °C, between invasive and native amphipods that were unparasitised or parasitised by a common acanthocephalan, Echinorhynchus truttae. Shredding results were compared using the relative impact potential (RIP) metric to investigate how they impacted the scale with a numerical response. Although per capita shredding was higher for the native amphipod at all temperatures, the higher abundance of the invader led to higher relative impact scores; hence, the replacement of the native by the invasive amphipod is predicted to drive an increase in shredding. This could be interpreted as a positive effect on the ecosystem function, leading to a faster accumulation of amphipod biomass and a greater rate of fine particulate organic matter (FPOM) provisioning for the ecosystem. However, the high density of invaders compared with natives may lead to the exhaustion of the resource in sites with relatively low leaf detritus levels.

Glacier retreat reorganizes river habitats leaving refugia for Alpine invertebrate biodiversity poorly protected

Alpine river biodiversity around the world is under threat from glacier retreat driven by rapid warming, yet our ability to predict the future distributions of specialist cold-water species is currently limited. Here we link future glacier projections, hydrological routing methods and species distribution models to quantify the changing influence of glaciers on population distributions of 15 alpine river invertebrate species across the entire European Alps, from 2020 to 2100. Glacial influence on rivers is projected to decrease steadily, with river networks expanding into higher elevations at a rate of 1% per decade. Species are projected to undergo upstream distribution shifts where glaciers persist but become functionally extinct where glaciers disappear completely. Several alpine catchments are predicted to offer climate refugia for cold-water specialists. However, present-day protected area networks provide relatively poor coverage of these future refugia, suggesting that alpine conservation strategies must change to accommodate the future effects of global warming.

A meta-analysis of environmental responses to freshwater ecosystem restoration in China (1987-2018)

Understanding how abiotic and biotic components respond to aquatic ecosystem restoration is pivotal for sustainable development in the face of economic development and global environmental change. However, the post-restoration monitoring and evaluation of aquatic ecosystems across large spatial and temporal scales is underfunded or not well documented, especially outside of Europe and North America. We present a meta-analysis of abiotic and biotic indices to quantify post-restoration (2 months-13 years) effects from reported aquatic restoration projects throughout the China-mainland, incorporating 39 lentic and 36 lotic ecosystems. Decreases in dissolved nutrients (total nitrogen, ammonia nitrogen and total phosphorus) post-restoration were rapid, but tended to slow down after about 9.3 years. Response ratios summarizing biodiversity responses (incorporating phytoplankton, invertebrates, vascular plants, fish and birds) typically lagged behind abiotic changes, suggesting longer timescales are needed for biotic indices to recover. Time since restoration interacted with lentic project size showing that, even with the same proportional efforts of restoration, larger lentic ecosystems responded much more slowly than smaller ones. Spatial heterogeneity, reflecting the effects of different restoration approaches (e.g., sewage interception, polluted sediment dredging, artificial wetlands, etc.), had a significantly stronger effect on biotic than abiotic indices, particularly in rivers compared to standing waters. This reflects the complexity of fluvial ecosystem dynamics and hints at a limitation in the reinstatement of ecological processes in these systems to overcome issues such as dispersal limitations. Overall, the different timelines and processes by which abiotic and biotic indices recover after restoration should be taken into account when defining restoration targets and monitoring programs. Our study illustrates the value of long-term aquatic ecosystem monitoring, especially in China given the scale and magnitude of ongoing restoration investments in the country.

High concentrations of pharmaceuticals emerging as a threat to Himalayan water sustainability

The sixth UN Sustainable Development Goal, Clean Water and Sanitation, directly underpins other goals of Health, Life in Water and Sustainable Cities. We highlight that poor sanitation, exemplified through some of the highest concentrations of pharmaceuticals ever detected in rivers, will amplify societal and environmental stress where climate-induced reductions in flow are predicted. Rapidly growing urban centres with inadequate water treatment works will need to prioritise water quality improvement before supply reductions become a reality. For 23 river locations within Kathmandu City and the Annapurna region, Nepal, we show the presence of 28 of 35 monitored human-use pharmaceuticals. Concentrations of antibiotics measured in this sampling campaign in both Kathmandu City (sulfamethazine, metronidazole and ciprofloxacin) and rural locations (ciprofloxacin) are in excess of predicted no effect concentrations, suggesting these sites are at risk of proliferating antimicrobial resistance as well as affecting other ecotoxicological endpoints. It is anticipated that climate-induced reductions in flow combined with contaminated river systems will amplify future societal and environmental stress.

High Concentrations of Pharmaceuticals in a Nigerian River Catchment

Pharmaceutical contamination of the environment is recognized as a global problem although most research has focused on Europe and North America to date, and there remains a dearth of information for developing countries, including those in Africa. To address this data gap, the occurrence of 37 pharmaceuticals belonging to 19 therapeutic classes was monitored in surface water and effluents in Lagos State, Southwest Nigeria. Samples were collected quarterly between April 2017 and March 2018 from 22 sites, and 26 compounds were detected at least once, many in the µg/L range. Maximum concentrations for those compounds detected ranged from 75 to 129 µg L^-1 , and even mean concentrations for 13 compounds were in the order of µg L^-1 . These values are among the highest ever measured globally. Sewage effluent was more important than drug manufacturing waste in polluting rivers, although there are likely to be numerous unregulated sources of effluent being discharged to rivers that require further study, including urban waste collection areas and vacuum trucks that collect effluent. Seasonal trends in the data were complex, with some compounds being found at higher concentrations in the dry season and, conversely, others being greater during the wet period; this variation potentially relates to the variety of pollution sources in the catchment. Pharmaceuticals are indispensable to human health, although their usage and discharge into the aquatic environment may lead to ecological problems and antibiotic resistance. The data we present indicate that pharmaceutical pollution of freshwaters is a serious issue in Nigeria, and management efforts are needed to improve this problem. Environ Toxicol Chem 2022;41:551-558. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Accelerated mass loss of Himalayan glaciers since the Little Ice Age

Himalayan glaciers are undergoing rapid mass loss but rates of contemporary change lack long-term (centennial-scale) context. Here, we reconstruct the extent and surfaces of 14,798 Himalayan glaciers during the Little Ice Age (LIA), 400 to 700 years ago. We show that they have lost at least 40 % of their LIA area and between 390 and 586 km³ of ice; 0.92 to 1.38 mm Sea Level Equivalent. The long-term rate of ice mass loss since the LIA has been between - 0.011 and - 0.020 m w.e./year, which is an order of magnitude lower than contemporary rates reported in the literature. Rates of mass loss depend on monsoon influence and orographic effects, with the fastest losses measured in East Nepal and in Bhutan north of the main divide. Locally, rates of loss were enhanced with the presence of surface debris cover (by 2 times vs clean-ice) and/or a proglacial lake (by 2.5 times vs land-terminating). The ten-fold acceleration in ice loss we have observed across the Himalaya far exceeds any centennial-scale rates of change that have been recorded elsewhere in the world.

A global agenda for advancing freshwater biodiversity research

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.

Mitigation of urbanization effects on aquatic ecosystems by synchronous ecological restoration

Ecosystem degradation and biodiversity loss have been caused by economic booms in developing countries over recent decades. In response, ecosystem restoration projects have been advanced in some countries but the effectiveness of different approaches and indicators at large spatio-temporal scales (i.e., whole catchments) remains poorly understood. This study assessed the effectiveness of a diverse array of 440 aquatic restoration projects including wastewater treatment, constructed wetlands, plant/algae salvage and dredging of contaminated sediments implemented and maintained from 2007 to 2017 across more than 2000 km² of the northwest Taihu basin (Yixing, China). Synchronized investigations of water quality and invertebrate communities were conducted before and after restoration. Our analysis showed that even though there was rapid urbanization at this time, nutrient concentrations (NH₄⁺-N, TN, TP) and biological indices of benthic invertebrate (taxonomic richness, Shannon diversity, sensitive taxon density) improved significantly across most of the study area. Improvements were associated with the type of restoration project, with projects targeting pollution-sources leading to the clearest ecosystem responses compared with those remediating pollution sinks. However, in some locations, the recovery of biotic communities appears to lag behind nutrients (e.g., nitrogen and phosphorus), likely reflecting long-distance re-colonization routes for invertebrates given the level of pre-restoration degradation of the catchment. Overall, the study suggests that ecological damage caused by recent rapid economic development in China could potentially be mitigated by massive restoration investments synchronized across whole catchments, although these effects could be expected to be enhanced if urbanization rates were reduced at the same time.

Extreme flood disturbance effects on multiple dimensions of river invertebrate community stability

Multidimensional analysis of community stability has recently emerged as an overarching approach to evaluating ecosystem response to disturbance. However, the approach has previously been applied only in experimental and modelling studies. We applied this concept to an 18-year time series (2000-2017) of macroinvertebrate community dynamics from a southeast Alaskan river to further develop and test the approach in relation to the effects of two extreme flood events occurring in 2005 (event 1) and 2014 (event 2). Five components of stability were calculated for pairs of pre- or post-event years. Individual components were tested for differences between pre- and post-event time periods. Stability components' pairwise correlations were assessed and ellipsoids of stability were developed for each time period and compared to a null model derived from the permuted dataset. Only one stability component demonstrated a significant difference between time periods. In contrast, 80% of moderate and significant correlations between stability components were degraded post-disturbance and significant changes to the form of stability ellipsoids were observed. Ellipsoids of stability for all periods after the initial disturbance (2005) were not different to the null model. Our results illustrate that the dimensionality of stability approach can be applied to natural ecosystem time-series data. The major increase in dimensionality of stability observed following disturbance potentially indicates significant shifts in the processes which drive stability following disturbance. This evidence improves our understanding of community response beyond what is possible through analysis of individual stability components.

Changes in EMG and movement velocity during a set to failure against different loads in the bench press exercise

This study examined changes in movement velocity and surface electromyographic (sEMG) activity of the pectoralis major (PM) and triceps brachii (TB) muscles during the bench press exercise to failure against different loads. Fourteen men performed a set to failure with maximum intended velocity, against low (40%-1 repetition maximum-RM), moderate (60%-1RM), and heavy loads (80%-1RM). Number of repetitions, volume load, mean and peak velocity, and total time increased with decreasing load (40% > 60% > 80%, p < 0.01). sEMG comparisons between different loads were performed by matching time under tension at the initial, middle, and last part of the set. sEMG was higher in the middle and last repetitions, compared with the initial, for all loads in both muscles (p < 0.001). sEMG activity of both muscles was higher in the 60% and 80%-1RM conditions compared with the 40%1-RM (p < 0.007). Also, sEMG of both muscles was similar for the 60%-1RM and 80%-1RM loads at the initial, middle, and last repetitions, with the exception of the last repetitions for the TB muscle. In contrast, sEMG integrated activity was higher for the 40% 1-RM and 60% 1-RM (p < 0.01) compared with the 80% 1-RM load. Mean velocity loss at exhaustion and drop in sEMG median frequency were greater in the 40% and 60%-1RM compared with the 80%-1RM condition (p < 0.05). It was concluded that performing a set to exhaustion with maximum intended velocity using a load of 60% 1-RM combines the characteristics of the high average sEMG activity of heavier loads, and the high total integrated sEMG observed at lighter loads.

Trait-based ecology at large scales: Assessing functional trait correlations, phylogenetic constraints and spatial variability using open data

The growing use of functional traits in ecological research has brought new insights into biodiversity responses to global environmental change. However, further progress depends on overcoming three major challenges involving (a) statistical correlations between traits, (b) phylogenetic constraints on the combination of traits possessed by any single species, and (c) spatial effects on trait structure and trait-environment relationships. Here, we introduce a new framework for quantifying trait correlations, phylogenetic constraints and spatial variability at large scales by combining openly available species' trait, occurrence and phylogenetic data with gridded, high-resolution environmental layers and computational modelling. Our approach is suitable for use among a wide range of taxonomic groups inhabiting terrestrial, marine and freshwater habitats. We demonstrate its application using freshwater macroinvertebrate data from 35 countries in Europe. We identified a subset of available macroinvertebrate traits, corresponding to a life-history model with axes of resistance, resilience and resource use, as relatively unaffected by correlations and phylogenetic constraints. Trait structure responded more consistently to environmental variation than taxonomic structure, regardless of location. A re-analysis of existing data on macroinvertebrate communities of European alpine streams supported this conclusion, and demonstrated that occurrence-based functional diversity indices are highly sensitive to the traits included in their calculation. Overall, our findings suggest that the search for quantitative trait-environment relationships using single traits or simple combinations of multiple traits is unlikely to be productive. Instead, there is a need to embrace the value of conceptual frameworks linking community responses to environmental change via traits which correspond to the axes of life-history models. Through a novel integration of tools and databases, our flexible framework can address this need.

Caffeine's Effects on an Upper-Body Resistance Exercise Workout

Salatto, RW, Arevalo, JA, Brown, LE, Wiersma, LD, and Coburn, JW. Caffeine's effects on an upper-body resistance exercise workout. J Strength Cond Res 34(6): 1643-1648, 2020-The purpose of this study was to examine the effects of caffeine on an upper-body resistance exercise workout. Fifteen men (mean ± SD: age, 23.1 ± 1.9 years; body mass, 89.1 ± 13.9 kg; height, 175 ± 6.1 cm) volunteered to come to the laboratory 3 times. During visit 1, 1-repetition maximum (RM) values were determined for the barbell bench press, incline barbell bench press, and dumbbell bench press exercises. For visit 2, subjects consumed either 800-mg caffeine or a placebo. Subjects then completed 3 sets to failure of each exercise using 80% of their 1RM. Visit 3 was the same as visit 2; however, participants consumed the opposite treatment as visit 2. Various perceptual measures were recorded before, during, and after the workouts. The results indicated that participants completed significantly more repetitions per set for the barbell bench press (4.80 ± 2.66) and incline barbell bench press (4.91 ± 2.29) in the caffeine condition compared with the placebo condition (4.42 ± 2.56 and 4.36 ± 2.11, respectively). Higher arousal scores were found in the caffeine condition. For vigor, participants reported higher scores with caffeine before warming up (caffeine = 10.20 ± 4.11, placebo = 6.20 ± 3.23) and mid workout (caffeine = 13.53 ± 2.29, placebo = 11.13 ± 2.79). These results suggest that caffeine has an ergogenic effect on strength workout performance due, at least in part, to positive effects on workout perception. Athletes and recreational lifters may want to consider the ingestion of caffeine before a resistance exercise workout.

Effects of Different Combinations of Concentric and Eccentric Resistance Training Programs on Traditional and Alternative Hamstrings-to-Quadriceps Ratios

Resistance training is often recommended for combined increases in traditional and alternative hamstrings-to-quadriceps (H:Q) ratios in order to reduce knee strength imbalance and associated hamstrings and knee ligament injury risk. The aim of this study was to investigate the effect of different concentric and eccentric resistance training programs on traditional and alternative H:Q ratios. Forty male volunteers were assigned to one of 4 groups: concentric quadriceps and concentric hamstrings (CON/CON, n = 10), eccentric quadriceps and eccentric hamstrings (ECC/ECC, n = 10), concentric quadriceps and eccentric hamstrings (CON/ECC, n = 10), or no training (control (CNTRL), n = 10). Traditional conventional (CR) and functional (FR), alternative rate of torque development (RTD), muscle size (MS), and muscle activation (MA) H:Q ratios were measured before and after six weeks of unilateral nondominant knee extension-flexion resistance training performed on an isokinetic dynamometer. The ECC/ECC training significantly increased FR (pre = 0.75 ± 0.11; post = 0.85 ± 0.15), whereas the lack of training (CNTRL) decreased the RTD H:Q ratio (pre = 1.10 ± 0.67; post = 0.73 ± 0.33). There were no differences between groups for the other traditional and alternative ratios following resistance training protocols. These findings suggest eccentric exercise for quadriceps and hamstrings as the most beneficial training program for inducing increases in the traditional FR. However, different resistance training strategies may be needed to also elicit increases in the alternative RTD, MS, and MA H:Q ratios for fully restoring muscle balance and reducing potential hamstrings and knee ligament injury risk.

Periodized versus Non-periodized Stretch Training on Gymnasts Flexibility and Performance

Static stretching (SS) can increase joint range of motion (ROM), due to neural, morphological, and physio-psychological factors. Periodized training programs (PD) (e. g., strength, power) are adopted to induce greater adaptations while avoiding overtraining. However, the effectiveness of periodized stretch training adaptations are unknown. Therefore, the objective of this study was to compare the effects of periodized and non-periodized (NP) stretching programs on flexibility, hamstrings stiffness and muscle performance. Sixteen gymnasts were allocated to either periodized or non-periodized SS training and tested pre- and post-8 weeks for countermovement jump height, hip flexors, hip extensors and dorsiflexors ROM, hamstrings stiffness and hamstrings and quadriceps peak torque. Both stretch training groups significantly and similarly increased hip extensor (33.2%), hip flexor (25.2%), and dorsiflexor (23.8%) ROM, hamstrings peak torque (7.9%) and jump height (8.1%) from pre - to post- training. Both groups decreased hamstrings stiffness across the last ten angles (32.1%). PD elicited consistently large magnitude flexibility effect size changes compared to small and moderate magnitude changes for the non-periodized. Therefore, 8-week PD and NP SS programs can decrease young gymnasts' muscle-tendon stiffness and increase muscle performance. However, effect sizes indicate that PD stretch training was more advantageous to increasing flexibility and improving performance.

Comparison Between Unilateral and Bilateral Plyometric Training on Single- and Double-Leg Jumping Performance and Strength

Bogdanis, GC, Tsoukos, A, Kaloheri, O, Terzis, G, Veligekas, P, and Brown, LE. Comparison between unilateral and bilateral plyometric training on single- and double-leg jumping performance and strength. J Strength Cond Res 33(3): 633-640, 2019-This study compared the effects of unilateral and bilateral plyometric training on single- and double-leg jumping performance, maximal strength, and rate of force development (RFD). Fifteen moderately trained subjects were randomly assigned to either a unilateral (U, n = 7) or bilateral group (B, n = 8). Both groups performed maximal effort plyometric leg exercises 2 times per week for 6 weeks. The B group performed all exercises with both legs, whereas the U group performed half the repetitions with each leg, so that total exercise volume was the same. Jumping performance was assessed by countermovement jumps (CMJs) and drop jumps (DJs), whereas maximal isometric leg press strength and RFD were measured before and after training for each leg separately and both legs together. Countermovement jump improvement with both legs was not significantly different between U (12.1 ± 7.2%) and B (11.0 ± 5.5%) groups. However, the sum of right- and left-leg CMJ only improved in the U group (19.0 ± 7.1%, p < 0.001) and was unchanged in the B group (3.4 ± 8.4%, p = 0.80). Maximal isometric leg press force with both legs was increased similarly between groups (B: 20.1 ± 6.5%, U: 19.9 ± 6.2%). However, the sum of right- and left-leg maximal force increased more in U compared with B group (23.8 ± 9.1% vs. 11.9 ± 6.2%, p = 0.009, respectively). Similarly, the sum of right- and left-leg RFD0-50 and RFD0-100 were improved only in the U group (34-36%, p < 0.01). Unilateral plyometric training was more effective at increasing both single- and double-leg jumping performance, isometric leg press maximal force, and RFD when compared with bilateral training.

Velocity-specific knee strength between professional and under-17 female volleyball players

Background

Many studies have investigated isokinetic performance in volleyball players but not through surface maps.

Objectives

The goals of this study were to assess velocity-specific isokinetic knee extensor–flexor muscle strength and to compare the isokinetic knee extensor–flexor muscles between professional (PRO) and under-17 (U17) female volleyball players.

Method

This cross-sectional laboratory study was developed with two groups: PRO (n = 12), median_age = 21.3 years, and U17 (n = 9), median_age = 15 years. Peak torque, total work, mean power, angle of peak torque, hamstring–quadriceps torque ratio (H–Q ratio) and torque–angle–velocity surface maps were analysed from knee extension–flexion at 60, 120 and 300 degrees per second (°/s).

Results

Significant differences were identified for extensor peak torque between PRO x = 202.3 Newton metre (N·m) (standard deviation [SD] = 24.4) and U17 x = 141.6 N·m (30.1) at 60 °/s (p < 0.001; d = 2.21) as well as flexor peak torque (PRO x = 75.7 N·m [10.3] and U17 x = 57.7 N·m [11.4]) at 120 °/s (p < 0.001; d = 1.65) for the dominant limb. There were also significant group differences for total work and mean power at all velocities for extension and flexion. Surface maps demonstrated higher torque at lower speeds for both groups with smaller torque changes across velocities for flexion.

Conclusion

Different groups of female volleyball players showed contrasting concentric knee muscle strength across isokinetic velocities.

Clinical implications

These results demonstrate the importance of specific strength training for different age groups, even within the same sport, and provide insight into muscle strength.

Initial results from the New Horizons exploration of 2014 MU69, a small Kuiper Belt object

The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU₆₉, a cold classical Kuiper Belt object approximately 30 kilometers in diameter. Such objects have never been substantially heated by the Sun and are therefore well preserved since their formation. We describe initial results from these encounter observations. MU₆₉ is a bilobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color or compositional heterogeneity. No evidence for satellites, rings or other dust structures, a gas coma, or solar wind interactions was detected. MU₆₉'s origin appears consistent with pebble cloud collapse followed by a low-velocity merger of its two lobes.

Alternative Methods of Determining Hamstrings-to-Quadriceps Ratios: a Comprehensive Review

The hamstrings-to-quadriceps muscle strength ratio calculated by peak torque has been used as an important tool to detect muscle imbalance, monitor knee joint stability, describe muscle strength properties and functionality, and for lower extremity injury prevention and rehabilitation. However, this ratio does not consider other neuromuscular variables that can also influence the antagonist to agonist muscle relationship, such as torque produced at multiple angles of range of motion, explosive strength, muscle size, muscle fatigue, or muscle activation. The aim of this study was to comprehensively review alternative methods of determining the hamstrings-to-quadriceps ratio. These include ratios calculated by angle-specific torque, rate of torque development, muscle size, fatigue index, and muscle activation (measured by electromyography). Collectively, the literature demonstrates that utilizing alternative methods of determining the hamstrings-to-quadriceps ratio can be functionally relevant for a better understanding of the neuromuscular mechanisms underpinning the interaction of strength between hamstrings and quadriceps. However, there is insufficient evidence to recommend any of the alternative methods as sensitive clinical tools for predicting injury risk and monitoring knee joint integrity. Future longitudinal studies, along with injury incidence, are needed to further investigate all alternative methods of determining the hamstrings-to-quadriceps ratio. These have potential to offer insight into how athletes and the general population should be trained for performance enhancement and injury reduction, and may be used along with traditional methods for a thorough assessment of an individual’s H:Q muscle balance.

Antioxidant Supplementation Impairs Changes in Body Composition Induced by Strength Training in Young Women

Strength training (ST) is known to promote muscle hypertrophy and body composition adaptations. However, only a few studies investigated the effects of ST combined with antioxidant supplementation (AS) on these adaptations. The aim of this study was to investigate chronic effects of ST combined with AS on fat mass (FM) and fat-free mass (FFM) of young women. In a double-blinded design, thirty-three subjects (22.9 ± 2.5 years, 57.7 ± 8.4 kg, 1.6 ± 0.6 m) were allocated into three groups: 1) vitamins (n=12), 2) placebo (n=11) and 3) control (n=10). Vitamins and placebo underwent a ST program for 10 weeks. Vitamins supplemented with vitamin C (1g/day) and E (400IU/day) during the training period. FM and FFM were assessed by DEXA. Multiple 3 x 2 (group x time) mixed-factor ANOVA with Tukey adjustment was performed to examine differences in the dependent variables. The significance level was set at P ≤ .05. Only placebo increased total FFM (34.9 ± 4.9 vs 36.3 ± 4.8 kg, P<0.05) and decreased total FM (21.8 ± 7.8 vs 21.0 ± 8.3 kg, P<0.05) after training for 10 weeks. Moreover, only placebo presented a significantly greater FFM percent change from pre to post-intervention compared to control (4.0 ± 3.4 vs -0.7 ± 3.1%, respectively, P < 0.05). These results suggest that chronic AS can mitigate ST related improvements of body composition in young women.

Sediment deposition from eroding peatlands alters headwater invertebrate biodiversity

Land use and climate change are driving widespread modifications to the biodiverse and functionally unique headwaters of rivers. In temperate and boreal regions, many headwaters drain peatlands where land management and climate change can cause significant soil erosion and peat deposition in rivers. However, effects of peat deposition in river ecosystems remain poorly understood. We provide two lines of evidence-derived from sediment deposition gradients in experimental mesocosms (0-7.5 g/m² ) and headwaters (0.82-9.67 g/m² )-for the adverse impact of peat deposition on invertebrate community biodiversity. We found a consistent negative effect of sediment deposition across both the experiment and survey; at the community level, decreases in density (1956 to 56 individuals per m² in headwaters; mean 823 ± 129 (SE) to 288 ± 115 individuals per m² in mesocosms) and richness (mean 12 ± 1 to 6 ± 2 taxa in mesocosms) were observed. Sedimentation increased beta diversity amongst experimental replicates and headwaters, reflecting increasing stochasticity amongst tolerant groups in sedimented habitats. With increasing sedimentation, the density of the most common species, Leuctra inermis, declined from 290 ± 60 to 70 ± 30 individuals/m² on average in mesocosms and >800 individuals/m² to 0 in the field survey. Traits analysis of mesocosm assemblages suggested biodiversity loss was driven by decreasing abundance of invertebrates with trait combinations sensitive to sedimentation (longer life cycles, active aquatic dispersal of larvae, fixed aquatic eggs, shredding feeding habit). Functional diversity metrics reinforced the idea of more stochastic community assembly under higher sedimentation rates. While mesocosm assemblages showed some compositional differences to surveyed headwaters, ecological responses were consistent across these spatial scales. Our results suggest short-term, small-scale stressor experiments can inform understanding of "real-world" peatland river ecosystems. As climate change and land-use change are expected to enhance peatland erosion, significant alterations to invertebrate biodiversity can be expected where these eroded soils are deposited in rivers.

Muscle Fiber and Performance Changes after Fast Eccentric Complex Training

INTRODUCTION

The purpose of this study was to examine the effects of a short-term fast eccentric and ballistic complex training program on muscle power, rate of force development (RFD), muscle fiber composition, and cross-sectional area (CSA).

METHODS

Sixteen male physical education students were randomly assigned to either a training group (TG, n = 8) or a control group (n = 8). The TG followed a 6-wk low volume training program, including fast eccentric squat training with an individually optimized load of 74% ± 7% of maximal half-squat strength (1RM) twice per week and a ballistic training session with loaded (30% 1RM) and unloaded jump squats, once per week, all combined with unloaded plyometric jumps.

RESULTS

Half squat 1RM was increased in the TG from 1.87 ± 0.28 to 2.14 ± 0.31 kg per kilogram body mass (14.4% ± 9.3%, P = 0.01). The percentage of types I, IIA, and IIX fibers were similar in the two groups at pretesting and did not change after the intervention period (P = 0.53-0.89). Muscle fiber CSA increased in all fiber types by 8.3% to 11.6% (P = 0.02 to 0.001) in TG only. Countermovement jump height and peak power measured at five different external loads (0%-65% of 1RM) only increased in the TG by approximately 20% to 36% (P < 0.01) and approximately 16% to 22% (P < 0.01), respectively. Peak ground reaction force during jump squats remained unchanged in both groups, whereas RFD increased in the TG only (40%-107%, P = 0.001).

CONCLUSIONS

A combination of low-volume fast eccentric and ballistic jump squat training with plyometric jumps in a strength-power potentiation complex format, induced substantial increases in peak leg muscle power, RFD, and maximal strength, accompanied by gains in CSA of all muscle fiber types, without a reduction in fast twitch fiber composition.

Global patterns and drivers of ecosystem functioning in rivers and riparian zones

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

Declining glacier cover threatens the biodiversity of alpine river diatom assemblages

Climate change poses a considerable threat to the biodiversity of high altitude ecosystems worldwide, including cold-water river systems that are responding rapidly to a shrinking cryosphere. Most recent research has demonstrated the severe vulnerability of river invertebrates to glacier retreat but effects upon other aquatic groups remain poorly quantified. Using new data sets from the European Alps, we show significant responses to declining glacier cover for diatoms, which play a critical functional role as freshwater primary producers. Specifically, diatom α-diversity and density in rivers presently fed by glaciers will increase with future deglaciation, yet β-diversity within and between sites will reduce because declining glacier influence will lower the spatiotemporal variability of glacier cover and its associated habitat heterogeneity. Changes in diatom assemblage composition as glacier cover declined were associated strongly with increasing riverbed stability and water temperature. At the species level, diatoms showed a gradation of responses; for example, Eunotia trinacria, found exclusively at river sites with high (≥52%) catchment glacier cover, may be affected negatively by ice loss. Conversely, seven taxa confined to sites with no glacier cover, including Gomphonema calcareum, stand to benefit. Nineteen (22%) taxa were noted as threatened, endangered, rare or decreasing on the Red List of Algae for Germany, with most at sites ≤26% glacier cover, meaning further ice loss may benefit these diatoms. However, six taxa found only in rivers ≥28% glacier cover may require reclassification of their Red List conservation status, as this habitat is threatened by deglaciation. Our identification of clear links between decreasing glacier cover and river diatom biodiversity suggests there could be significant reorganization of river ecosystems with deglaciation, for example, through alterations to primary production, biogeochemical cycles, and the shifting resource base of alpine freshwater food webs which lack significant allochthonous energy inputs.

Effects of Static Versus Ballistic Stretching on Hamstring:Quadriceps Strength Ratio and Jump Performance in Ballet Dancers and Resistance Trained Women

Stretching, while enhancing joint flexibility, may also decrease the hamstring:quadriceps (H:Q) strength ratio, which is used to identify knee strength imbalances and lower extremity muscle and ligament injury risk in the practice of sports and other physical activities. Stretching may also decrease muscle force and jump performance. However, these effects may depend on the population in question and mode of stretching. The purpose of this study was to compare the effects of static stretching (SS) and ballistic stretching (BS) on concentric H:Q ratio, squat jump (SJ) and countermovement jump (CMJ) height, and SJ:CMJ ratio between ballet dancers and resistance trained women. Fifteen resistance trained women and 12 ballet dancers were tested over five sessions. The first visit consisted of demographic measurements and instruction in testing protocols (no stretching), while the other four involved SS or BS in a counterbalanced order. At each of these sessions, six stretching exercises were performed, three focusing on quadriceps and three on hamstrings, in counterbalanced order. Two way repeated measures ANOVAs were used to compare interactions between conditions and groups for H:Q and SJ:CMJ ratios. Both groups demonstrated a significant decrease in H:Q ratio after SS, but there were no significant differences in SJ:CMJ ratio or jump height between conditions (p > 0.001). However, the ballet group had greater SJ:CMJ ratios and SJ heights than the resistance trained group. These findings suggest that both ballet dancers and resistance trained women decrease H:Q ratio similarly after BS and SS. Long-duration stretching negatively impacts H:Q ratio in the short term, which may lead to greater hamstring to quadriceps imbalance regardless of training background.

Effect of strength training combined with antioxidant supplementation on muscular performance

This was a placebo-controlled randomized study that aimed to investigate the effects of strength training (ST) combined with antioxidant supplementation on muscle performance and thickness. Forty-two women (age, 23.8 ± 2.7 years; body mass, 58.7 ± 11.0 kg; height, 1.63 ± 0.1 m) were allocated into 3 groups: vitamins (n = 15), placebo (n = 12), or control (n = 15). The vitamins and placebo groups underwent an ST program, twice a week, for 10 weeks. The vitamins group was supplemented with vitamins C (1 g/day) and E (400 IU/day) during the ST period. Before and after training, peak torque (PT) and total work (TW) were measured on an isokinetic dynamometer, and quadriceps muscle thickness (MT) was assessed by ultrasound. Mixed-factor ANOVA was used to analyze data and showed a significant group × time interaction for PT and TW. Both the vitamins (37.2 ± 5.4 to 40.3 ± 5.6 mm) and placebo (39.7 ± 5.2 to 42.5 ± 5.6 mm) groups increased MT after the intervention (P < 0.05) with no difference between them. The vitamins (146.0 ± 29.1 to 170.1 ± 30.3 N·m) and placebo (158.9 ± 22.4 to 182.7 ± 23.2 N·m) groups increased PT after training (P < 0.05) and PT was higher in the placebo compared with the control group (P = 0.01). The vitamins (2068.3 ± 401.2 to 2295.5 ± 426.8 J) and placebo (2165.1 ± 369.5 to 2480.8 ± 241.3 J) groups increased TW after training (P < 0.05) and TW was higher in the placebo compared with the control group (P = 0.01). Thus, chronic antioxidant supplementation may attenuate peak torque and total work improvement in young women after 10 weeks of ST.

River ecosystem resilience to extreme flood events

Floods have a major influence in structuring river ecosystems. Considering projected increases in high-magnitude rainfall events with climate change, major flooding events are expected to increase in many regions of the world. However, there is uncertainty about the effect of different flooding regimes and the importance of flood timing in structuring riverine habitats and their associated biotic communities. In addition, our understanding of community response is hindered by a lack of long-term datasets to evaluate river ecosystem resilience to flooding. Here we show that in a river ecosystem studied for 30 years, a major winter flood reset the invertebrate community to a community similar to one that existed 15 years earlier. The community had not recovered to the preflood state when recurrent summer flooding 9 years later reset the ecosystem back to an even earlier community. Total macroinvertebrate density was reduced in the winter flood by an order of magnitude more than the summer flood. Meiofaunal invertebrates were more resilient to the flooding than macroinvertebrates, possibly due to their smaller body size facilitating greater access to in-stream refugia. Pacific pink salmon escapement was markedly affected by the winter flood when eggs were developing in redds, compared to summer flooding, which occurred before the majority of eggs were laid. Our findings inform a proposed conceptual model of three possible responses to flooding by the invertebrate community in terms of switching to different states and effects on resilience to future flooding events. In a changing climate, understanding these responses is important for river managers to mitigate the biological impacts of extreme flooding effects.

ISOKINETIC MUSCLE PERFORMANCE AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: A CASE-CONTROL STUDY

BACKGROUND

and Purpose: Knee muscle strength deficits have been reported in individuals who have undergone anterior cruciate ligament reconstruction (ACLR). Isokinetic testing is a valid way to assess muscle strength. Some isokinetic variables, including the range of motion in the phases to attain a specific velocity, load range (sustained specific velocity), time to achieve deceleration, and qualitative analysis of the torque-angle velocity relationship, may contribute to understanding recovery of these individuals after surgery. Thus, the purpose of this study was to compare the load range (LR), time to attain velocity (TTAV), deceleration time (DT) phases, total range of motion (ROM), peak torque/body mass (PT/BM), angle of peak torque (AngPT) during LR and torque-angle-velocity relationships (TAV_3D) between post ACLR and matched control subjects.Study design: Case-control.

METHODS

Seven men who underwent ACLR and seven matched controls were evaluated from four to six months after surgery. Testing was performed on a Biodex System 4 isokinetic dynamometer in concentric mode at 60, 120 and 300 °/s, for knee flexion and extension.

RESULTS

Statistically significant differences were seen for extension ROM at 60 °/s where ROM was greater in the control group. PT/BM for extensors was also significantly greater in controls by 20 % compared to ACLR at 60 and 120 °/s. PT/BM for flexors was significantly greater for controls at 60 °/s (∼15 %). TAV_3D showed differences in torque and, specifically, the control group sustained knee flexion torque for a greater range of motion when compared to the ACLR group.

CONCLUSION

The ACL group presented with lower ROM and PT/BM, therefore exhibiting worse muscle performance in comparison to the control group.Level of Evidence: 3.

NO EFFECT OF KINESIOLOGY TAPE ON PASSIVE TENSION, STRENGTH OR QUADRICEPS MUSCLE ACTIVATION OF DURING MAXIMAL VOLUNTARY ISOMETRIC CONTRACTIONS IN RESISTANCE TRAINED MEN

BACKGROUND

Kinesiology Tape (KT) is widely used in sports rehabilitation and by those performing physical activity, however, there is no consensus in the scientific literature about its effectiveness on performance, strength or muscle activation.Purpose: The purpose of this study was to measure the acute effects of KT in static rest, and during knee extension maximal voluntary isometric contraction (MVIC) performance in resistance trained men.Study Design: Observational, descriptive, comparative.

METHODS

Eighteen young, healthy, trained males (age: 25 ± 6 years, height: 176.0 ± 5 cm, and mass: 81.8 ± 8.0 kg) volunteered to participate. Initially, they were in a relaxed sitting position of 90 degrees knee flexion with their limb supported by the machine lever arm to measure passive tension of the tissues of the knee joint. Then, they performed three MVIC trials of five seconds each with a three-minute rest between trials, in four randomized experimental conditions, with 10-min rest between conditions: (a) control, no taping; (b) Knee Sleeve; (c) KT; and (d) sham. During all MVICs, peak force, impulse, and muscle activation of the vastus lateralis (integrated electromyography [IEMG] and median frequency) were measured.

RESULTS

Repeated measures ANOVAs revealed no statistical differences between conditions for passive tension (p > 0.05), peak force (p > 0.05), impulse (p > 0.05), IEMG (p > 0.05), or median frequency (p > 0.05).

CONCLUSION

KT does not influence passive tension during static position at 90 degrees of knee flexion. KT does not affect quadriceps activation or force production during a maximal voluntary isometric contraction in the same position.

LEVEL OF EVIDENCE

3a.

Balance and Lower Limb Muscle Activation between In-Line and Traditional Lunge Exercises

In-line and traditional lunge exercises present differences in technique as lower limb positioning (anterioposterior), and medio-lateral (ML) balance may differentially affect primary and stabilizer muscles. The purposes of this study were to examine ML balance and muscle activation in anterior and posterior leg positions between in-line and traditional lunge exercises. Fifteen young, healthy, resistance-trained men (25 ± 5 years) performed 2 different lunge exercises (in-line and traditional) at their 10 repetition maximum in a randomized, counterbalanced fashion. Surface electromyography measured muscle activation of the vastus lateralis, biceps femoris, gluteus maximus, and gluteus medius. ML balance was measured with a Wii Fit Balance Board. The vastus lateralis activity was not significantly different between exercises or leg positions. The biceps femoris activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to the posterior position for the in-line (p = 0.003), and traditional lunge (p < 0.001). The gluteus maximus activity was not significantly different between exercises, however, it was significantly greater in the anterior compared to posterior position for the in-line (p < 0.001) and traditional lunge (p < 0.001). ML balance was significantly greater in the in-line exercise in the anterior limb (p = 0.001). Thus, both in-line and traditional lunge exercises presented similar overall levels of muscle activation, yet the anterior limb generated the highest biceps femoral and gluteus maximus muscle activation when compared to the posterior limb. The in-line lunge presents greater ML balance when compared to the traditional lunge exercise.

Determination of Vertical Jump as a Measure of Neuromuscular Readiness and Fatigue

Watkins, CM, Barillas, SR, Wong, MA, Archer, DC, Dobbs, IJ, Lockie, RG, Coburn, JW, Tran, TT, and Brown, LE. Determination of vertical jump as a measure of neuromuscular readiness and fatigue. J Strength Cond Res 31(12): 3305-3310, 2017-Coaches closely monitor training loads and periodize sessions throughout the season to create optimal adaptations at the proper time. However, only monitoring training loads ignores the innate physiological stress each athlete feels individually. Vertical jump (VJ) is widely used as a measure of lower-body power, and has been used in postmatch studies to demonstrate fatigue levels. However, no pretraining monitoring by VJ performance has been previously studied. Therefore, the purpose of this study was to determine the sensitivity of VJ as a measure of readiness and fatigue on a daily sessional basis. Ten healthy resistance-trained males (mass = 91.60 ± 13.24 kg; height = 179.70 ± 9.23 cm; age = 25.40 ± 1.51 years) and 7 females (mass = 65.36 ± 12.29 kg; height = 162.36 ± 5.75 cm; age = 25.00 ± 2.71 years) volunteered to participate. Vertical jump and BRUNEL Mood Assessment (BAM) were measured 4 times: pre-workout 1, post-workout 1, pre-workout 2, and post-workout 2. Workout intensity was identical for both workouts, consisting of 4 sets of 5 repetitions for hang cleans, and 4 sets of 6 repetitions for push presses at 85% 1 repetition maximum (1RM), followed by 4 sets to failure of back squats (BSs), Romanian deadlift, and leg press at 80% 1RM. The major finding was that VJ height decrement (-8.05 ± 9.65 cm) at pre-workout 2 was correlated (r = 0.648) with BS volume decrement (-27.56 ± 24.56%) between workouts. This is important for coaches to proactively understand the current fatigue levels of their athletes and their readiness to resistance training.