Maximum Strength Research Articles

Effect of overlapping deposition strategy on microstructure and mechanical properties of Al-clad steel by AFSD

Cladding of the aluminum (Al) layer on steel was successfully implemented via additive friction stir deposition (AFSD). We revealed the relationship between the overlapping deposition strategy of AFSD and the resultant microstructure and mechanical properties of Al-clad steel for the first time. Overlapping deposition strategies efficiently improved the adhesion of the Al layer on steel in the boundary region owing to the sufficient material flow and large plastic deformation. This is in contrast to the sample without overlapping where the Al/steel interface in the boundary region is characterized by holes and weak bonding. In particular, the maximum shear strength (109.0 MPa) was obtained for the sample with an overlap of 8 mm, even higher than that of the single-pass sample. This study provided a novel approach to the fabrication of large-scaled clad layers on hard substrates, and this strategy is expected to greatly contribute to the adoption of AFSD in the fields of cladding, joining, and coating.

Hydrothermal solidification of siliceous and calcareous wastes into building materials: A generic mix design framework

The presence of inactive components in siliceous and calcareous wastes tends to cause a misunderstanding in their mix design for hydrothermal solidification. The contents of typical reactive elements (i.e. Caact, Siact and Alact) in raw materials are quickly determined by simulating hydrothermal conditions. A generic mix design framework is proposed, which utilizes the molar ratio of Caact/Siact as the controlling parameter. The framework was demonstrated through a series of studies, which involved the production of granular materials using a mixture of clayey soil with slaked lime, as well as the production of compacted cylinders using a mixture of clayey soil with either slaked lime or calcium carbide slag. Experimental results showed that the hydrothermal samples achieved their maximum strength when the molar ratio of Caact/Siact in raw materials approached the theoretical Ca/Si molar ratio (i.e. 0.83) in tobermorite, provided that the molar ratio of Alact/(Alact + Siact) remained below 21%.

Trunk Flexor and Extensor Muscle Strength Capacity in Healthy Individuals

Objective: Generating reference values of trunk muscle strength is of value for specific age groups and gender in every society. The aim of this study was to define flexor and extensor muscle strength of the trunk and the flexion/extension ratio in healthy individuals. Materials and Methods: Hundred and two healthy individuals were included in this study. Isokinetic concentric strength of trunk flexor (Flex) and extensor (Ext) muscles of the participants were measured via an isokinetic dynamometer. Tests were performed at speeds of 60°/s and 180°/s. Maximum strength was characterized with peak torque (PT) (Flexabs, Extabs; N·m), peak torque normalized to body weight (PTNBW) (Flexnorm, Extnorm; N·m·kgbw-1), and Flexabs/Extabs ratio. Results: For angular velocity of 600/s, PT and PTNBW of flex and ext strength were higher in men; while for angular velocity of 1800/s, PTNBW of flex and ext strength were higher in women (p<0.05). Extensor strength for 600/s and 1800/s angular velocities yielded lower values than flexor strength in both genders. The Flexabs/Extabs ratios were 1.67±0.62 for 600/s and 4.93±4.60 for 1800/s. Conclusion: Trunk extensor strength was higher than flexor strength in men and women at 600/s and 1800/s angular velocities. In this study, the ratio of Flexabs/Extabs was not within the accepted range in non-active adults and there was no difference between men and women, indicating that muscle strength is not sufficient in this population. The data of this study can be used as a comparison parameter in future studies to get normative data, or common values in healthy individuals aged 18-30.

Systematic Evaluation of Isometric Maximal Muscle Strength in an Orthopaedic Cohort.

Although the lower extremities are essential for movement function and human gait, no normalized isometric maximum strength values, which include the factors gender, age, weight, height, and body mass index (BMI), have been defined to date for orthopaedic patients. To systematically analyze the isometric maximal muscle strength of a cohort in an orthopaedic outpatient clinic and to evaluate its relation to gender, age, weight, height, BMI, and the differences between diseases. Cross-sectional study. Level 4. Isometric maximal muscle strength of knee extension, knee flexion, hip abduction, and hip adduction was measured in orthopaedic patients of an outpatient clinic using a specific muscle strength measurement device. Correlation analysis was performed for age, gender, height, weight, and BMI. Patients were grouped by disease characteristics. The cohort consisted of 311 subjects (sex: 164 male, 147 female; age: 48.63 years, SD = 16.595; BMI: 26.56 kg/m², SD = 4.9). Age correlated significantly with maximal isometric muscle strength. At the age of 54 years onward, based on 133 patients, a decline in maximum isometric muscle strength was detected. Gender showed a strong influence on maximal isometric muscle strength, with significantly higher values for male patients. Furthermore, weight and height, but not BMI, correlated significantly with muscle strength. For clinical studies comparing different evidence-based training interventions for rehabilitation, it is important to consider determinants such as gender, age, weight, and height for isometric maximum strength measurement. For further validation, follow-up examinations taking into account the performance level, other target groups, and other muscle groups are required to avoid the wide dispersion of isometric maximum strength values. These results and associated determinants are highly clinically relevant and can be used as a reference for further studies in the field of musculoskeletal regeneration.

Wear behaviour of Al-MWCNT composites by varying MWCNTs concentration

The present study illustrates the mechanical and wear behaviour of Al-MWCNT composites by varying MWCNTs concentration (0 %,0.25 %, 0.50 % & 1 %) by weight in composites. These composites were synthesized through sintering in the muffle furnace after mechanical alloying which involved flattening and welding particles to form flake-shaped lamellar particles. The presence of MWCNT lamellas restricted grain growth, creating a 2D aluminium layer between the MWCNTs during sintering. Increasing the MWCNT content in aluminum refined the interlayer thickness of the composites. The compressive strength of Al is increased exponentially with the addition of CNTs. By adding CNTs to aluminium, the maximum strength was reached at 460 MPa in 1% samples, and the compression strength of the aluminium increased by 84 % as well. The sintered composites exhibited higher hardness and its value increased significantly when CNTs were added to the Al composite. The wear resistance of aluminium is substantially increased when CNTs are added, and the maximum wear resistance is achieved when CNTs are added at 0.5 wt%. The addition of CNTs reduced wear resistance, which could be attributed to the decrease in interface adhesion and agglomeration effects of CNTs.

Vapour permeation characteristics of aliphatic alcohols through PVA/PVC thin films

Nonsolvent induced phase separation (NIPS) method using NMP/water system was adopted to prepare PVA/PVC thin films and were characterized by FTIR & FE-SEM analysis. Mechanical strength measurements indicated that an optimum composition of PVA/PVC has maximum tensile strength and might be due to the intercalation of viscous PVA into the stiff PVC matrix. Degree of swelling (DS) and water contact angle (WCA) measurements showed greater wettability of the films with increasing PVA content as is revealed from the higher film porosity and diminished contact angle. Pure water flux (PWF) and mean pore size were studied to determine the water permeation capacity of the film. Vapour permeability of various films was evaluated by using three different aliphatic alcohols viz. Methanol, ethanol and propanol. Barrier property and selectivity in permeation were studied for a particular PVA/PVC composition with moderate number and size of the pores which exhibited minimum permeation capacity.

Reveal of relationship between microscopy architecture and mechanical performance of Y/Bi substituted Bi-2212 engineering ceramics.

This study aims to find out how the crystallinity quality, surface morphology, and mechanical performances change with the substitution of yttrium (Y) for bismuth (Bi) impurity within molar ratios of 0.00 ≤ x ≤ 0.12 in the Bi2.0-xYxSr2.0Ca1.1Cu2.0Oy (Bi-2212) cuprates to reveal the dependence of micro surface topology on the substitution mechanism and achieve a strong relation between the impurity ions and crystallization mechanism. The materials are prepared by ceramic method. It is found that all the experimental findings improve remarkably with increasing yttrium impurity molar ratio of x = 0.01. Scanning electron microscopy (SEM) images indicate that the optimum Y ions strengthen the formation of flaky adjacent stacked layers due to the changes of thermal expansion, vibration amplitude of atoms, heat capacitance, reaction kinetics, activation energy, nucleation temperature, thermodynamic stability, and intermolecular forces. Besides, new engineering novel compound produced by optimum Y ions presents the best crystallinity quality, uniform surface view, greatest coupling interaction between grains, largest particle size distributions/orientations, and densest/smoothest surface morphology. Hardness measurement results totally support the surface morphology view. Moreover, mechanical design properties and durability of the tetragonal phase improve significantly with increasing replacement level of x = 0.01 due to the induction of new surface residual compressive stress areas, slip systems, and chemical bonding between the foreign and host atoms. Besides, the same sample exhibits the maximum strength and minimum sensitivity to loads depending on reduction of stored internal strain energy and degree of granularity. Consequently, cracks tend to propagate predominantly within the transcrystalline regions. Furthermore, each material investigated exhibits the characteristic behavior of the indentation size effect. In summary, the optimum Y-doped Bi-2212 sample paves the way for the expanded use of engineering ceramics across various applications based on the enhanced service life. RESEARCH HIGHLIGHTS: The presence of the optimum yttrium impurity significantly decreases the Ea value. As the Y/Bi replacement increases up to the molar substitution level of x = 0.01, the mechanical design properties and durability of the tetragonal phase enhance significantly.

A new strategy for manufacturing, modeling, and optimization of 3D printed polylactide based on multiple nonlinear neuro regression analysis and stochastic optimization methods

Although there are many studies related to design, modeling, and optimization of fused deposition modeling (FDM) process parameters in the literature, the absence of a systematic approach to increase the reliability of model selection and optimization results is an important shortcoming that must be addressed. To make up for this deficiency, a new strategy was proposed to obtain desired quality on mechanical properties by adjusting FDM process parameters. This attempt involves manufacturing, modeling, and optimization point of view. The D-optimal method was employed to form experiment set, including process parameters. A hybrid approach neuro regression combining artificial neural network (ANN) and regression analysis together was used for modeling of FDM process. The most significant advantage of the neuro-regression approach compared to ANN is that the mathematical models can be used directly without needing any transformation. This is not possible in neural networks and, therefore, significantly limits and complicates the use of models obtained using ANN. The present study aims at optimization of the FDM process parameters, including infill density, infill pattern, layer thickness, and print speed on ultimate strength, fracture strength, and fracture strain for polylactide (PLA). In this regard, modified versions of the optimization algorithms Differential Evolution, Nelder Mead, and Simulated Annealing were used to find the best or elite designs. Linear or nonlinear models consisting of polynomial, trigonometric, and logarithmic expressions and their hybrid forms were employed to define the strength and strain behavior of PLA. It is concluded that (a) implementations of the optimization algorithms provide a 19% improving the minimum strain value if it is compared with the experimental results, (b) infill pattern types ( x2) were found as honeycomb, triangle, and cubic for the designs in terms of maximum fracture strength, minimum strain, and maximum ultimate tensile strength respectively, (c) many alternatives near optimum local designs could be obtained based on Nelder Mead algorithm for fracture strength and ultimate strength parameters. Thus, this allows work in a wide range of applications without depending on a single result for production.

Thermal, electrical, and mechanical performances of ultrahigh-performance cementitious composites with multiwalled carbon nanotubes

This study examines the influence of multiwalled carbon nanotubes (MWCNTs) on cementitious composites, specifically focusing on the fabrication of multifunctional cementitious composites known as ultrahigh-performance cementitious (UHPC) composites. Key properties such as compressive strength, thermal performance, and electrical resistance were examined with varying MWCNT contents, curing methods, curing duration, and supply voltage. The effects of the incorporation of MWCNTs on the hydration reactions of the cementitious composites were analyzed using field-emission scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction. The study revealed that MWCNT UHPC composites can achieve a maximum ultrahigh strength of 120.8 MPa. Additionally, the incorporation of MWCNTs enabled the composites to reach a maximum surface temperature of 90.6 °C during heating. Furthermore, the power consumption of MWCNT UHPC composites was found to be predictable based on the curing type and the duration of curing. Notably, the hydration reactions in MWCNT UHPC composites remained unaffected by the MWCNT content. The findings emphasize the potential of multifunctional MWCNT UHPC composites by offering exceptional strength, heating capabilities, and electrical performance in construction materials.

Tongue strength and swallowing-related masseter activity and oropharyngeal timing across the lifespan

Purpose: This study examined lifespan changes in maximum tongue strength, swallowing time, and masseter activity during swallowing. It provides normative data with which to compare clinical assessments of orofacial myofunctional disorders (OMD) and oropharyngeal dysphagia (OPD). Method: 409 healthy participants without identified OMD or OPD (ages 5 – 79 years) provided instrumental measures of tongue strength and electromyographic measurements for oropharyngeal transit time and masseter activity during swallows of four boluses. Participants were placed in three broad age groups (5 – 15, 16 – 59, 60 – 79) for crosssectional analysis. Results: Differences were found between age groups for tongue strength, such that the youngest group had significantly lower anterior tongue strength than the other groups, and lower posterior tongue strength than the 16 – 59 age group. Anterior tongue strength was significantly greater for males than females; posterior tongue strength did not differ significantly between the sexes. The youngest group had longer oropharyngeal transit times than either of the two older groups for most boluses. Swallowing transit time decreased in duration across the age groups, from youngest to oldest, for the 2.5 cc pudding bolus. Both right and left masseters differed in activation among tasks and age groups. The oldest age group had consistently greater levels of activation of the right masseter, and all groups had greater activation for the cracker bolus. Spearman rank-order correlations largely confirmed the inferential statistics and provided evidence of a relationship between tongue weakness and increased oropharyngeal transit time. Conclusion: Maximum tongue pressure generation and oropharyngeal timing measures support a developmental hypothesis, with lower tongue strength and longer swallowing transit times for children ages 5 through 15. The smaller pudding bolus provided the greatest differentiation among the age groups, which may prove to be a functional indicator for clinical evaluation. These results are largely consistent with existing data for tongue strength and oropharyngeal swallowing transit times.

Interface needle structure induced high-performance aluminum alloy/PPS hybrids

Direct joining molding of metals and polymers has received increasing attention in the field of lightweight fabrication. The aluminum alloy (Al) surface was modified by secondary anodizing and a special needle-like structure was formed on the Al surface. Then, the glass fiber-filling polyphenylene sulfide (PPS) was directly joined with Al by the hot pressing technique. The relationship between the interfacial structure and mechanical properties of Al/PPS hybrids was systematically investigated and discussed. The results showed that the generation of needle-like structures could improve the surface roughness and wettability, thus effectively improving the mechanical interlocking ability of the interface and forming the Al-O-C chemical bond with PPS. The maximum tensile strength of Al/PPS hybrids was 28.34 MPa, and their impact toughness (ak) reached 9.69 J/cm2. Even though the hybrids were exposed to a salt spray environment or 200 °C, the strength could still reach 25 MPa. This study has prepared a high-performance metal/plastic hybrid by secondary anodizing method, which can be applied in harsh environments.

Innovative Cross-Sectional Configurations for Low-Cost Bamboo Composite (LCBC) Structural Columns

This paper investigates the effect of innovative cross-sectional configurations on Low-Cost Bamboo Composite (LCBC) structural members. The study employs both experimental and numerical methods with different resin matrices and bamboo species. In this study, LCBC short columns are designed with different innovative cross-sectional configurations in an attempt to overcome the costly production processes of engineered bamboo. This approach uses bundles of bamboo, both in culm and strip forms. A compatible, environmentally responsible, and economically justifiable resin matrix is used to fabricate an LCBC member. The production of LCBC members does not necessitate highly advanced technology. This capability enables the production of LCBC members in custom-designed cross-sectional shapes and lengths. This study introduces the Russian doll (RD), Big Russian doll (BRD), Hawser (HAW), and Scrimber (SCR) cross-sectional configurations. Extra-large, large, medium, and small sizes of bamboo are employed. Synthetic Epoxy (EXP), a Bio-based Experimental soft filler (BE1), Bio-Epoxy (BE2), Furan-based (PF1) matrices are applied. Furthermore, Moso, Guadua, Madake, and Tali bamboo species are incorporated. The results of this study reveal that the most efficient cross-sectional configuration for compressive strength is the HAW configuration, closely followed by the SCR configuration. LCBC members with bio-resins have shown excellent promise in competing in strength with those made with their synthetic counterparts. The maximum compressive strengths (MPa) were achieved by two specimens with synthetic epoxy closely followed by a specimen with bio-epoxy, namely HAW-EPX-M, RD-EPX-M, and RD-BE2-G specimens with 78 MPa, 75 MPa, and 72 MPa, respectively. In terms of the modulus of elasticity of LCBC with different resin matrices, the stiffest specimens were HAW-BE2-M1, HAW-EPX-M, and HAW-BE2-M2 with 3.89 GPa, 3.08 GPa, and 2.54 GPa, respectively. The theoretical and numerical modelling of the LCBC members showed excellent correlation with the experimental results, which provides the capacity to design LCBC for engineering projects. The LCBC design can be further developed with more bamboo and less resin content.

Developing Accurate Repetition Prediction Equations for Trained Older Adults with Osteopenia.

The aim of this study was to evaluate prediction equations to estimate 1RM in different exercises in older men and women with osteopenia/osteoporosis. Forty well-trained older women and men (73 ± 8 years) with osteopenia/osteoporosis performed 1RM dynamic and isometric maximum strength tests on resistance devices. In addition, each participant performed repetitions-to-fatigue (RTF) in the 5-8RM, 9-12RM, and 13-16RM zones. After evaluating the predictive performance of available 1RM prediction equations from the literature, new prediction equations were developed for all seven exercises. One of the available equations that focus on postmenopausal women already acceptably predicted 1RM from RTF for all but one exercise. Nevertheless, new exercise-specific prediction equations based on a cubic polynomial most accurately predict 1RM from RTF in the 5-8 reps range with mean absolute differences between predicted and actual 1RM of 3.7 ± 3.7% (leg-press) to 6.9 ± 5.5% (leg flexion) that is roughly within the acceptable coefficient of variation. For some exercises, the inclusion of the isometric maximum strength tests slightly increases the prediction performance of the 5-8RM. In conclusion, the present prediction equation accurately estimates 1RM in trained, older women and men with osteopenia/osteoporosis. Further evaluation of this new equation is warranted to determine its applicability to different age groups and populations.

Flexible loofah sponge-based phase change composite for thermal protection and wearable thermal management

To address the escalating demand for sophisticated thermal management in electronics, energy batteries, and wearable devices, extensive research has been dedicated to developing shape-stabilized and highly thermally conductive phase change composites (PCCs). However, their inherent rigidity and limited flexibility pose significant challenges for practical applications. In response, we have engineered a novel and flexible PCC by integrating loofah sponge (LS) and styrene-isoprene-styrene block copolymer (SIS) as co-supporting framework with paraffin wax (PW) as heat storage medium, further enhanced with carbon nanotubes (CNTs). The process began with the vacuum adsorption of PW into an ammonia-softened LS, which forming a fibrous network. This was followed by the introduction of a mixed melt of SIS and PW, physically cross-linked and dispersed with CNTs, into the LS fibrous network. The composite was then cooled and shaped to produce the (final) PCC. The resultant PCC exhibited remarkable ductility with an elongation of approximately 780 % and a maximum tensile strength of ∼2 MPa. Furthermore, it maintained thermal reliability and dimensional stability over long-term usage, with a melting heat enthalpy as high as 146.4 J/g. This flexible PCC, which combines high latent thermal energy storage, temperature regulation, and thermally induced assembly properties, shows considerable promise for thermal protection and portable thermal management in electronic devices.

Strategi Mengurangi Sampah Plastik di Desa Citasuk

This research shows that plastic bricks use plastic waste as a mixed material, offering an innovative solution in the construction sector that is more environmentally friendly and sustainable. The raw material used in making these bricks is plastic waste, which will reduce the amount of plastic waste thrown away in landfills. And the use of recycled plastic waste 5 (PP) polypropylene as a binding material in the paving block mixture produces maximum compressive strength.

Customized Pore Creation Strategies for Hyperelastic, Robust, Insulating Multifunctional MXene Aerogels for Microwave Absorption.

The construction of heterogeneous microstructure and the selection of multicomponents have turned into a research hotspot in developing ultralight, multifunctional, high-efficiency electromagnetic wave absorbing (EMA) materials. Although aerogels are promising materials to fulfill the above requirements, the increase in functional fillers inevitably leads to the deterioration of intrinsic properties. Tuning the electromagnetic properties from the structural design point of view remains a difficult challenge. Herein, we design customized pore creation strategies via introducing sacrificial templates to optimize the conductive path and construct the discontinuous dielectric medium, increasing dielectric loss and achieving efficient microwave absorption properties. A 3D porous composite (MEM) was crafted, which encapsulated an EVA/FeCoNi (EVA/MNPs) framework with Ti3C2Tx MXene coating by employing a direct heated cross-linking and immersion method. Controllable adjustment of the conductive network inside the porous structure and regulation of the dielectric character are achieved by porosity variation. Eventually, the MEM-5 with a porosity of 66.67% realizes RLmin of -39.2 dB (2.2 mm) and can cover the entire X band. Moreover, through off-axis electronic holography and the calculation of conduction loss and polarization loss, the dielectric property is deeply investigated, and the inner mechanism of optimization is pointed out. Thanks to the inherent characteristic of EVA and the porous structure, MEM-5 showed excellent thermal insulating and superior compressibility, which can maintain 60 °C on a 90-100 °C continuous heating stage and reached a maximum compressive strength of 60.12 kPa at 50% strain. Conceivably, this work provides a facile method for the fabrication of highly efficient microwave absorbers applied under complex conditions.

High-Performance Flexible Sensor with Sensitive Strain/Magnetic Dual-Mode Sensing Characteristics Based on Sodium Alginate and Carboxymethyl Cellulose.

Flexible sensors can measure various stimuli owing to their exceptional flexibility, stretchability, and electrical properties. However, the integration of multiple stimuli into a single sensor for measurement is challenging. To address this issue, the sensor developed in this study utilizes the natural biopolymers sodium alginate and carboxymethyl cellulose to construct a dual interpenetrating network, This results in a flexible porous sponge that exhibits a dual-modal response to strain and magnetic stimulation. The dual-mode flexible sensor achieved a maximum tensile strength of 429 kPa and elongation at break of 24.7%. It also exhibited rapid response times and reliable stability under both strain and magnetic stimuli. The porous foam sensor is intended for use as a wearable electronic device for monitoring joint movements of the body. It provides a swift and stable sensing response to mechanical stimuli arising from joint activities, such as stretching, compression, and bending. Furthermore, the sensor generates opposing response signals to strain and magnetic stimulation, enabling real-time decoupling of different stimuli. This study employed a simple and environmentally friendly manufacturing method for the dual-modal flexible sensor. Because of its remarkable performance, it has significant potential for application in smart wearable electronics and artificial electroskins.

Strengthening Polymer Concrete with Carbon and Basalt Fibres

To date, composite materials, such as polymer concrete, have found wide application in various industries due to their unique properties combining high strength, resistance to aggressive media and durability. Improving the performance characteristics of polymer concrete is an important task aimed at expanding the areas of its application. One of the promising methods of increasing the strength of this material is the use of various fillers. In this paper, the effect of fillers, based on carbon and basalt fibres, on the mechanical properties of polymer concrete was investigated. The polymer concrete was made of the following components: rubble stone, sand, quartz flour and polyester resin. During the experimental work, the amount of carbon and basalt fibres in the polymer concrete mixture varied from 0 to 6%. Bending and compressive strength tests showed that the addition of carbon and basalt fibres increased these properties. The highest bending and compressive strengths were achieved when carbon fibre contents were up to 1.5%, while basalt fibres provided the highest strengths in the case of around 2%. These results confirmed that carbon fibres had a higher efficiency in strengthening polymer concrete compared to that of basalt fibres. This could be explained by the fact that carbon fibres had a higher tensile strength and modulus of elasticity, which allowed them to better redistribute loads within the composite material. The fibre length for carbon fibre, which gave the maximum increase in properties, was 10–15 mm. For basalt fibre, the maximum bending strength was reached at 20 mm and compressive strength at 10 mm. Increasing the content of carbon fibre above 2% and basalt fibre above 1.5% did not give further increase in mechanical properties. In conclusion, it could be stated that the use of carbon fibres as fillers offered significant advantages in strengthening polymer concrete, opening up opportunities for its use in more demanding conditions and in a wider range of industrial applications.

High Cognitive Effort Prior to Velocity-Based Training Sessions Reduces Rate of Force Development but Not Maximum Strength Gains in Untrained Male Adults.

This study aimed to analyze the chronic effect of high cognitive effort immediately before resistance exercise sessions on neuromuscular performance in untrained male adults. We used a mixed experimental design, with the group as between-participants factor and time as within-participants factor. Thirty-four participants were randomly assigned to two parallel groups: high cognitive effort (n = 17) and control (n = 17). Subjects in the control group were seated for 30 min before the resistance exercise sessions, while the high cognitive effort group completed incongruent trials of the Stroop task until subjective mental fatigue was present immediately before resistance exercise sessions. Participants attended 45 sessions over 15 weeks, consisting of three familiarizations, three baseline evaluations, 36 velocity-based training sessions, and three postexperiment evaluation sessions. Rate of force development (RFD) during the isometric mid-thigh pull, half back-squat 1-RM, and countermovement jump (CMJ) were measured before and after the 12-week intervention. A significant group × time interaction effect was found for the average RFD at 0-250 ms (p < 0.05), with greater improvements for the control group than for the high cognitive effort group. There was no group × time interaction for half back-squat 1-RM (p > 0.05). Also, there was no group × time interaction for CMJ (p > 0.05). In conclusion, repeated high cognitive effort immediately prior to resistance exercise sessions is a phenomenon that can induce greater early velocity loss and, consequently, impairs the improvements in RFD. However, this did not inhibit the increased performance for explosive strength and CMJ in male untrained adults. High cognitive effort before resistance exercise sessions should be avoided.

Effects of Spinal Decompression and Segmental Spinal Instrumentation on Lower Limb Functionality in Patients with Spinal Osteoarthritis.

Spinal osteoarthritis, a degenerative condition of the spine, significantly impairs quality of life, causing pain, stiffness, and limited mobility. Treatment primarily aims to improve functionality and quality of life. This study investigated the effects of lower back surgery (e.g., spinal decompression with vertebra stabilization) on upper-limb maximum strength, lower limb functionality, and quality of life in osteoarthritis patients. A total of 16 patients (♀ = 10 and ♂ = 6) patients from the orthopedic clinic who were diagnosed with osteoarthritis based on MRI and clinical symptoms underwent the surgery. Their handgrip strength, lower limb functionality (6 min walk test), and quality of life (Flanagan quality of life scale) were assessed before and after the surgery. A repeated measures ANOVA was conducted to assess differences in these metrics pre- and post-surgery across the entire patient cohort, as well as within gender-specific subgroups. A large positive effect was seen in the 6 min walk (p = 0.02, d = -0.83) test but not in the handgrip test or quality of life. However, female patients showed a trend towards better quality of life. The results of this study provide evidence for the effectiveness of surgery in the treatment of spinal osteoarthritis and underscore the need for personalized treatment approaches in the treatment of spinal osteoarthritis.