Maximal number of repetitions at percentages of the one repetition maximum: A meta-regression and moderator analysis of sex, age, training status, and exercise

The maximal number of repetitions that can be completed at various percentages of the one repetition maximum (1RM) [REPS ~ %1RM relationship] is foundational knowledge in resistance exercise programming. The current REPS ~ %1RM relationship is based on few studies and has not incorporated uncertainty into estimations or accounted for between-individuals variation. Therefore, we conducted a meta-regression to estimate the mean and between-individuals standard deviation of the number of repetitions that can be completed at various percentages of 1RM. We also explored if the REPS ~ %1RM relationship is moderated by sex, age, training status, and/or exercise. A total of 952 repetitions-to-failure tests, completed by 7289 individuals in 452 groups from 269 studies, were identified. Study groups were predominantly male (66%), healthy (97%), \u3c 59 years of age (92%), and resistance trained (60%). The bench press (42%) and leg press (14%) were the most commonly studied exercises. The REPS ~ %1RM relationship for mean repetitions and standard deviation of repetitions were best described using natural cubic splines and a linear model, respectively, with mean and standard deviation for repetitions decreasing with increasing %1RM. More repetitions were evident in the leg press than bench press across the loading spectrum, thus separate REPS ~ %1RM tables were developed for these two exercises. Analysis of moderators suggested little influences of sex, age, or training status on the REPS ~ %1RM relationship, thus the general main model REPS ~ %1RM table can be applied to all individuals and to all exercises other than the bench press and leg press. More data are needed to develop REPS ~ %1RM tables for other exercises. © 2023, The Author(s)

The Eccentric:Concentric Strength Ratio of Human Skeletal Muscle In Vivo:Meta-analysis of the Influences of Sex, Age, Joint Action, and Velocity

For decades, researchers have observed that eccentric (ECC) muscle strength is greater than concentric (CON) muscle strength. However, knowledge of the ECC:CON strength ratio is incomplete and might inform resistance exercise prescriptions. Our purposes were to determine the magnitude of the ECC:CON ratio of human skeletal muscle in vivo and explore if sex, age, joint actions/exercises, and movement velocity impact it. A total of 340 studies were identified through searches. It was possible to analyse 1516 ECC:CON ratios, aggregated from 12,546 individuals who made up 564 groups in 335 of the identified studies. Approximately 98% of measurements occurred on isokinetic machines. Bayesian meta-analyses were performed using log-ratios as response variables then exponentiated back to raw ratios. The overall main model estimate for the ECC:CON ratio was 1.41 (95% credible interval [CI] 1.38–1.44). The ECC:CON ratio was slightly less in men (1.38 [CI 1.34–1.41]) than women (1.47 [CI 1.43–1.51]), and greater in older adults (1.62 [CI 1.57–1.68]) than younger adults (1.39 [CI 1.36–1.42]). The ratio was similar between grouped upper-body (1.42 [CI 1.38–1.46]) and lower-body joint actions/exercises (1.40 [CI 1.37–1.44]). However, heterogeneity in the ratio existed across joint actions/exercises, with point estimates ranging from 1.32 to 2.61. The ECC:CON ratio was most greatly impacted by movement velocity, with a 0.20% increase in the ratio for every 1°/s increase in velocity. The results show that ECC muscle strength is ~ 40% greater than CON muscle strength. However, the ECC:CON ratio is greatly affected by movement velocity and to lesser extents age and sex. Differences between joint actions/exercises likely exist, but more data are needed to provide more precise estimates

CHARACTERISING SUCCESSFUL AND UNSUCCESSFUL AERIAL MANOEUVRES IN PROFESSIONAL SURFING COMPETITIONS

Although aerials are an effective way for a competitive surfer to increase their score during surfing competitions, less than half of aerial attempts are landed successfully during competition. This study aimed to identify which characteristics of performing an aerial during competition were associated with either a successful or unsuccessful landing. Video images of 121 aerials performed during the finals series of the 201 5 World Championship Tour season were qualitatively analysed. The Frontside Air Reverse was found to be the most commonly performed aerial, with critical features of landing, particularly features that improved a surfer's balanced landing position, significantly associated with successful aerials. These results provide evidence upon which coaches can modify a surfer's technique to encourage higher successful aerial completion rates

Transcriptome Analysis of \u3ci\u3eBifidobacterium Longum\u3c/i\u3e Strains that Show a Differential Response to Hydrogen Peroxide Stress

Consumer and commercial interest in foods containing probiotic bifidobacteria is increasing. However, because bifidobacteria are anaerobic, oxidative stress can diminish cell viability during production and storage of bioactive foods. We previously found Bifidobacterium longum strain NCC2705 had signifi- cantly greater intrinsic and inducible resistance to hydrogen peroxide (H2O2) than strain D2957. Here, we explored the basis for these differences by examining the transcriptional responses of both strains to sub-lethal H2O2 exposure for 5- or 60-min. Strain NCC2705 had 288 genes that were differentially expressed after the 5-min treatment and 114 differentially expressed genes after the 60-min treatment. In contrast, strain D2957 had only 21 and 90 differentially expressed genes after the 5- and 60-min treatments, respectively. Both strains showed up-regulation of genes coding enzymes implicated in oxidative stress resistance, such as thioredoxin, thioredoxin reductase, peroxiredoxin, ferredoxin, glutaredoxin, and anaerobic ribonucleotide reductase, but induction levels were typically highest in NCC2705. Compared to D2957, NCC2705 also had more up-regulated genes involved in transcriptional regulation and more down-regulated genes involved in sugar transport and metabolism. These results provide a greater understanding of the molecular basis for oxidative stress resistance in B. longum and the factors that contribute to strain-to-strain variability in survival in bioactive food products

Genome -Scale Reconstruction of Metabolic Networks of Lactobacillus casei ATCC 334 and 12A

Lactobacillus casei strains are widely used in industry and the utility of this organism in these industrial applications is straindependent. Hence, tools capable of predicting strain specific phenotypes would have utility in the selection of strains forspecific industrial processes. Genome-scale metabolic models can be utilized to better understand genotype-phenotyperelationships and to compare different organisms. To assist in the selection and development of strains with enhancedindustrial utility, genome-scale models for L. casei ATCC 334, a well characterized strain, and strain 12A, a corn silage isolate,were constructed. Draft models were generated from RAST genome annotations using the Model SEED database and refined by evaluating ATP generating cycles, mass-and-charge-balances of reactions, and growth phenotypes. After the validation process was finished, we compared the metabolic networks of these two strains to identify metabolic, genetic and ortholog differences that may lead to different phenotypic behaviors. We conclude that the metabolic capabilities of the two networks are highly similar. The L. casei ATCC 334 model accounts for 1,040 reactions, 959 metabolites and 548 genes, while the L. casei 12A model accounts for 1,076 reactions, 979 metabolites and 640 genes. The developed L. casei ATCC 334 and 12A metabolic models will enable better understanding of the physiology of these organisms and be valuable tools in the development and selection of strains with enhanced utility in a variety of industrial applications

Dilepton and Photon Emission Rates from a Hadronic Gas

We analyze the dilepton and photon emission rates from a hadronic gas using chiral reduction formulas and a virial expansion. The emission rates are reduced to pertinent vacuum correlation functions, most of which can be assessed from experiment. Our results indicate that in the low mass region, the dilepton and photon rates are enhanced compared to most of the calculations using chiral Lagrangians. The enhancement is further increased through a finite pion chemical potential. An estimate of the emission rates is also made using Haag's expansion for the electromagnetic current. The relevance of these results to dilepton and photon emission rates in heavy-ion collisions is discussed.Comment: 7 pages, LaTeX using revTeX, 6 figures imbedded in text. Figures slightly changed, text left unchange

Effect of Kisspeptin on Regulation of Growth Hormone

Kisspeptin ( KP ), a neuroendocrine regulator of reproduction, is hypothesized to be an integrator of metabolism and hormones critical to the regulation of reproduction. Lactation is associated with enhanced growth hormone (GH) responsiveness and reduced fertility. Our study was designed to determine the effects of lactation on KP-stimulated GH and luteinizing hormone (LH) secretion. Five non-lactating and five lactating dairy cows were used in the study. Experiments were conducted with lactating cows at weeks 1, 5 and 11 after parturition. The experimental treatments ( saline and KP [100 and 400 pmol / kg body weight]) were given intravenously and blood was collected and plasma was stored until later assay to determine concentrations of GH, LH, progesterone and non-esterified fatty acids. We found that neither dose of KP stimulated an increase in GH secretion. The low dose of KP increased (P \u3c0. 05) LH concentrations only in lactating cows. The higher dose of KP elicited an increase in circulating LH concentrations in both lactating and non-lactating cows. The lower dose of KP increased (P \u3c 0. 05) the area under the curve for LH only in cows during week 5 of lactation, and the area under the curve of LH following the highest dose of KP was greater (P \u3c 0. 05) in cows during week 5 of lactation than that for the other groups of cows. In summary, lactation status and stage of lactation did not change the sensitivity of the GH system to KP. However, an effect of stage of lactation on KP-stimulated LH secretion was detected in the dairy cows. Study of the KP system during lactation in dairy cows may provide critical insights into the mechanisms for lactation associated changes in the reproductive axis

A copper isotope investigation of methane cycling in Late Archaean sediments

This research was supported by NERC award NE/L002590/1 to the IAPETUS DTP, and by NERC Standard Grant NE/J023485/2 to A.L.Z. The initiation of Cu isotope analysis at the University of St Andrews was aided significantly by a Carnegie Trust Research Incentive Grant awarded to P.S.S.The rise of oxygenic photosynthesis arguably represents the most important evolutionary step in Earth history. Recent studies, however, suggest that Earth’s pre-oxidative atmosphere was also heavily influenced by biological feedbacks. Most notably, recent geochemical records propose the existence of a hydrocarbon haze which periodically formed in response to enhanced biospheric methane fluxes. Copper isotopes provide a potential proxy for biological methane cycling; Cu is a bioessential trace metal and a key element in the aerobic oxidation of methane to carbon dioxide (methanotrophy). In addition, Cu isotopes are fractionated during biological uptake. Here, we present a high-resolution Cu isotope record measured in a suite of shales and carbonates from core GKF01, through the ~2.6–2.5 Ga Campbellrand-Malmani carbonate platform. Our data show a 0.85‰ range in Cu isotope composition and a negative excursion that predates the onset of a haze event. We interpret this excursion as representing a period of enhanced aerobic methane oxidation before the onset of the Great Oxidation Event. This places valuable time constraints on the evolution of this metabolism and firmly establishing Cu isotopes as a biomarker in Late Archaean rocks.PostprintPeer reviewe

Quadriceps foam rolling and rolling massage increases hip flexion and extension passive range-of-motion

Increases in joint range-of-motion may be beneficial for improving performance and reducing injury risk. This study investigated the effects of different self-massage volumes and modalities on passive hip range-of-motion. Twenty-five recreationally resistance-trained men performed four experimental protocols using a counterbalanced, randomized, and within-subjects design; foam rolling (FR) or roller massage (RM) for 60 or 120-s. Passive hip flexion and extension range-of-motion were measured in a counterbalanced and randomized order via manual goniometry before self-massage (baseline) and immediately, 10-, 20-, and 30-min following each self-massage intervention. Following FR or RM of quadriceps, there was an increase in hip flexion range-of-motion at Post-0 (FR: Δ = 19.28°; RM: Δ = 14.96°), Post-10 (FR: Δ = 13.03°; RM: Δ = 10.40°), and Post-20 (FR: Δ = 6.00°; RM: Δ = 4.64°) for all protocols, but these did not exceed the minimum detectable change at Post-10 for RM60 and RM120, and Post-20 for FR60, FR120, RM60, and RM120. Similarly, hip extension range-of-motion increased at Post-0 (FR: Δ = 8.56°; RM: Δ = 6.56°), Post-10 (FR: Δ = 4.64°; RM: Δ = 3.92°), and Post-20 (FR: Δ = 2.80°; RM: Δ = 1.92°), but did not exceed the minimum detectable change at Post-10 for FR60, RM60, and RM120, and Post-20 for FR60, FR120, RM60, and RM120. In conclusion, both FR and RM increased hip range-of-motion but larger volumes (120- vs. 60-second) and FR produced the greatest increases. These findings have implications for self-massage prescription and implementation, in both rehabilitation and athletic populations

The Role of Nucleons in Electromagnetic Emission Rates

Electromagnetic emission rates from a thermalized hadronic gas are important for the interpretation of dilepton signals from heavy-ion collisions. Although there is a consensus in the literature about rates for a pure meson gas, qualitative differences appear with a finite baryon density. We show this to be essentially due to the way in which the pi-N background is treated in regards to the nucleon resonances. Using a background constrained by unitarity and broken chiral symmetry, it is emphasized that the thermalized hadronic gas can be considered dilute.Comment: 9 pages, 7 figures, minor change