Steady hydrodynamic interaction between human swimmers

Adobe Bricks of the Champagne Region (France): Characterization of a Chalky Raw Earth Construction Material

Raw earth bricks made from the soil of the Chalky Champagne region (France) have been used for at least two millennia in construction, a promising heritage in the context of reducing the carbon emissions of buildings. The present experimental study aims to measure the physical, mechanical, thermal, and hydric properties of adobes collected from a local village barn. The results show a high chalk content, estimated at 71%, and a clay content, acting as a binder, of 14%. Despite limited load-bearing capacity, these lightweight adobes are suitable for current single-story constructions, while their hydrothermal properties classify them as excellent moisture regulators for occupants. In association with other bio-sourced materials such as starch-beet pulp bricks, Chalky Champagne adobes yield promising insulating properties, and meet the criteria defined by current energy standards.

The Effect of Clinical Pilates Exercises and Prenatal Education on Maternal and Fetal Health

OBJECTIVE

The mental, physical and sexual health of women as well as maternal and fetal health should be considered during the prenatal and postnatal periods. Investigating the effect of clinical Pilates exercises and prenatal education (CPE & PE) on obstetric and neonatal outcomes as well as the mental, physical, and sexual health of women was intended.

METHODS

In the second trimester, mothers with singleton pregnancies who attended (n=79, study group) or did not attend (n=80, control group) CPE & PR were recruited to this prospective cohort study, and were evaluated in the prenatal and postnatal periods. Depression was assessed with Beck Depression Inventory (BDI), sexual functions with Female Sexual Function Index (FSFI), muscle strength with Gross Muscle Scales (GMS), and labor pain with Visual Analogue Scale (VAS). In addition, the presence of low back pain (LBP) was questioned.

RESULTS

No significant association of CPE & PE with obstetric outcomes such as cesarean rates, preterm birth, and neonatal outcomes such as birth weight and Apgar scores were identified. Changes in VAS scores, the incidence of perineal trauma, and episiotomy were not associated with CPE & PE. However, CPE & PE was associated with lower BDI scores, a gradual increase in the total scores of FSFI, increased GMS, and reduced LBP.

CONCLUSION

CPE & PE had no adverse effects on obstetric and neonatal outcomes and was associated with improved mental, physical, sexual health scores during pregnancy and postpartum.

Wake-Riding Effect-Inspired Opto-Hydrodynamic Diatombot for Non-Invasive Trapping and Removal of Nano-Biothreats

Contamination of nano-biothreats, such as viruses, mycoplasmas, and pathogenic bacteria, is widespread in cell cultures and greatly threatens many cell-based bio-analysis and biomanufacturing. However, non-invasive trapping and removal of such biothreats during cell culturing, particularly many precious cells, is of great challenge. Here, inspired by the wake-riding effect, a biocompatible opto-hydrodynamic diatombot (OHD) based on optical trapping navigated rotational diatom (Phaeodactylum tricornutum Bohlin) for non-invasive trapping and removal of nano-biothreats is reported. Combining the opto-hydrodynamic effect and optical trapping, this rotational OHD enables the trapping of bio-targets down to sub-100 nm. Different nano-biothreats, such as adenoviruses, pathogenic bacteria, and mycoplasmas, are first demonstrated to be effectively trapped and removed by the OHD, without affecting culturing cells including precious cells such as hippocampal neurons. The removal efficiency is greatly enhanced via reconfigurable OHD array construction. Importantly, these OHDs show remarkable antibacterial capability, and further facilitate targeted gene delivery. This OHD serves as a smart micro-robotic platform for effective trapping and active removal of nano-biothreats in bio-microenvironments, and especially for cell culturing of many precious cells, with great promises for benefiting cell-based bio-analysis and biomanufacturing.

Numerical and experimental methods used to evaluate active drag in swimming: A systematic narrative review

Introduction: In swimming, it is necessary to understand and identify the main factors that are important to reduce active drag and, consequently, improve the performance of swimmers. However, there is no up-to-date review in the literature clarifying this topic. Thus, a systematic narrative review was performed to update the body of knowledge on active drag in swimming through numerical and experimental methods.

Methods: To determine and identify the most relevant studies for this review, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach was used.

Results: 75 studies related to active drag in swimming and the methodologies applied to study them were analyzed and kept for synthesis. The included studies showed a high-quality score by the Delphi scale (mean score was 5.85 ± 0.38). Active drag was included in seven studies through numerical methods and 68 through experimental methods. In both methods used by the authors to determine the drag, it can be concluded that the frontal surface area plays a fundamental role. Additionally, the technique seems to be a determining factor in reducing the drag force and increasing the propulsive force. Drag tends to increase with speed and frontal surface area, being greater in adults than in children due to body density factors and high levels of speed. However, the coefficient of drag decreases as the technical efficiency of swimming increases (i.e., the best swimmers (the fastest or most efficient) are those with the best drag and swimming hydrodynamics efficiency).

Conclusion: Active drag was studied through numerical and experimental methods. There are significantly fewer numerical studies than experimental ones. This is because active drag, as a dynamical phenomenon, is too complex to be studied numerically. Drag is greater in adults than in children and greater in men than in women across all age groups. The study of drag is increasingly essential to collaborate with coaches in the process of understanding the fundamental patterns of movement biomechanics to achieve the best performance in swimming. Although most agree with these findings, there is disagreement in some studies, especially when it is difficult to define competitive level and age. The disagreement concerns three main aspects: 1) period of the studies and improvement of methodologies; 2) discrimination of methodologies between factors observed in numerical vs. experimental methods; 3) evidence that drag tends to be non-linear and depends on personal, technical, and stylistic factors. Based on the complexity of active drag, the study of this phenomenon must continue to improve swimming performance.

Exercise-Induced Muscle Damage and Protein Intake: A Bibliometric and Visual Analysis

Numerous studies have covered exercise-induced muscle damage (EIMD) topics, ranging from nutritional strategies to recovery methods, but few attempts have adequately explored and analyzed large volumes of scientific output. The purpose of this study was to assess the scientific output and research activity regarding EIMD and protein intake by conducting a bibliometric and visual analysis. Relevant publications from 1975-2022 were retrieved from the Web of Science Core Collection database. Quantitative and qualitative variables were collected, including the number of publications and citations, H-indexes, journals of citation reports, co-authorship, co-citation, and the co-occurrence of keywords. There were 351 total publications, with the number of annual publications steadily increasing. The United States has the highest total number of publications (26.21% of total publications, centrality 0.44). Institutional cooperation is mostly geographically limited, with few transnational cooperation links. EIMD and protein intake research is concentrated in high-quality journals in the disciplines of Sport Science, Physiology, Nutrition, and Biochemistry & Molecular Biology. The top ten journals in the number of publications are mostly high-quality printed journals, and the top ten journals in centrality have an average impact factor of 13.845. The findings of the co-citation clusters and major keyword co-occurrence reveal that the most discussed research topics are "exercise mode", "nutritional strategies", "beneficial outcomes", and "proposed mechanisms". Finally, we identified the following research frontiers and research directions: developing a comprehensive understanding of new exercise or training models, nutritional strategies, and recovery techniques to alleviate EIMD symptoms and accelerate recovery; applying the concept of hormesis in EIMD to induce muscle hypertrophy; and investigating the underlying mechanisms of muscle fiber and membrane damage.

Ankle joint flexibility affects undulatory underwater swimming speed

The movement of undulatory underwater swimming (UUS), a swimming technique adapted from whales, is mainly limited by human anatomy. A greater ankle joint flexibility could improve the imitation of the whale's flap of the fin and therefore enhance USS performance. The aim of this study was to investigate the impact of ankle joint flexibility on swimming velocity and kick efficiency during UUS by comparing kinematics of swimming trials with reduced, normal, and enhanced maximum angles of plantar flexion. Ten well trained swimmers (5m and 5f; 22 ± 4years; 177 ± 7cm; 74 ± 15kg), performed multiple trials of UUS with normal, restricted, and increased ankle joint flexibility on two separate days in randomized order. Kick frequency was controlled by a metronome. Plantar flexion (PF) was restricted by tape application on both feet and increased by passive-dynamic stretching. All trials were filmed. Kinematics were obtained with two-dimensional motion analysis. Tape application restricted maximum PF by 10.42% while stretching increased PF by 6.87% compared to normal PF. Swimming velocity and kick efficiency significantly decreased during swimming with restricted PF (1.13 ± 0.13m^*s⁻¹; 0.69 ± 0.09m) compared to normal (1.20 ± 0.14 m^*s⁻¹; 0.72 ± 0.10m) and increased (1.22 ± 0.15m^*s⁻¹; 0.73 ± 0.10m) PF. Swimming velocity and kick efficiency did not differ between normal and increased PF. Body height normalized swimming velocity correlated significantly with PF angle (r = 0.538). The results suggest that UUS velocity is affected by impaired PF. Particularly swimmers with low or average maximum PF angles may benefit from a long-term ankle joint flexibility program to improve their UUS performance.

Subjective Theories of Chinese Office Workers With Irregular Physical Activity: An Interview-Based Study

Objectives

Individuals with irregular physical activity (PA) participation are defined as fluctuators. This study aimed to comprehend how fluctuators’ perceived barriers and motivators in their subjective theories are exhibited and cognitively represented in relation to their everyday PA practices and lapses.

Methods

The design of “Research Program Subjective Theories” was used to explore and present fluctuators’ cognition concerning PA participation. Thirty fluctuators were invited to a semi-structured interview. By inductive and deductive coding, fluctuators’ verbal data were converted into word categories for extracting commonalities and comparing differences. By retaining the remaining word categories of high frequency and exploring the interrelationships among the remained word categories using statistical analyses, a superstructure (i.e., visualized representation of fluctuators’ overall cognition) including fluctuators’ main PA motivators, barriers, and behavioral outcomes was compiled.

Results

Fluctuators face common motivators as barriers, such as lack of time, lack of willpower, lack of social support, and physical reasons (discomfort, injuries, or diseases). Fluctuators’ subjective theories primarily differed in motivational configurations. The physically motivated fluctuators (i.e., those predominantly motivated by physically related motivators) were more linked with low PA level, while the mixed motivated fluctuators (i.e., motivated by both physically related and emotionally or socially related motivators) were more likely associated with moderate PA level. The exemplars of the three typical fluctuators were also demonstrated to reveal their real experiences and situations in the daily life context.

Conclusion

Due to the fact that fluctuation research is still in its infancy, this study represents a significant opportunity to promote knowledge growth in this area. Future studies are recommended to convert findings of the present study into interventions that benefit fluctuators in overcoming perceived barriers and enhancing motivations to eventually participate in regular PA.

Muscle Fatigue and Swimming Efficiency in Behind and Lateral Drafting

Drafting in swimming is a tactic in which an athlete (drafter) swims in the wave of another athlete (leader). Our aim was to compare the effects of this tactic on the drafter, as far as muscle fatigue, muscle activity, and swimming efficiency are concerned. Fifteen drafters performed three 200 m front crawl trials at a controlled submaximal pace in three configurations: Behind Drafting (BD), Lateral Drafting (LD), and Free Swimming (FS). Muscle fatigue, muscle activity, and swimming efficiency were obtained by surface electromyography (EMG) and video analysis from flexor carpi radialis, triceps brachii, latissimus dorsi, and rectus femoris muscles. The outcome measures were: time slope of Mean Frequency (MNF), for muscle fatigue; time slope of Root Mean Square (RMS), for muscle activity; and Stroke Index (SI) for swimming efficiency. Negative variations of MNF were 5.1 ± 1.7%, 6.6 ± 4.1%, and 11.1 ± 2.7% in BD, LD, and FS, respectively. Statistical significance was found for all cases except for the rectus femoris. Positive variations of RMS were 3.4 ± 1.2%, 4.7 ± 2.7%, and 7.8 ± 4.6% in BD, LD, and FS, respectively. Statistical significance was found only for the slopes of latissimus dorsi in FS and LD. The largest mean in SI was measured in the BD (2.01 m²/s), while the smallest was measured in the FS (1.86 m²/s). BD was found to be the best swimming configuration, in terms of lower muscle fatigue and higher swimming efficiency. Also, LD resulted to be advantageous with respect to FS.

Total mRNA and primary human myoblasts' in vitro cell cycle progression distinguishes between clones

Satellite cells are generally quiescent in vivo. Once activated, progression through the cell cycle begins. Immortalised myoblasts from a single cell line are fairly homogenous in culture, but primary human myoblasts (PHMs) demonstrate heterogeneity. This phenomenon is poorly understood however may impact on PHM expansion. This study aimed to evaluate cell cycle transition from growth to synthesis phases of the cell cycle (G1 to S phase) and total mRNA relevant to this transition in PHM clones derived from 2 donor biopsies. Proportions of cells transitioning from G1 to S phase were evaluated at 2-hourly intervals for 24 h (n = 3 for each) and total mRNA quantified. Both PHM clones revealed an exponential transition from G1 to S phase over time, with a significantly slower rate for PHMs from S9.1 compared to S6.3, which had a higher proportion of PHMs in S phase for most time-points (p < 0.05). After 24 h the proportion of PHMs in S phase was ∼13% (S6.3) compared to ∼22% (S9.1). Gene transcription increased as cells progressed from G1 to S phase. Although total RNA increased with similar linearity in both clones, S6.3 PHMs had consistently (10 out of 12 time points) significantly higher concentrations. Validating the 2-hourly assessment over 24 h, a 4-hourly assessment from 8 to 32 h revealed similar differences but included the beginning of a plateau. This study demonstrates that PHMs from different donors differ in both cell cycle progression and overall transcriptome revealing new aspects in the heterogeneity of isolated satellite cells in vitro.