Maximum Lifting Research Articles

Postural stability and risk of slips in lifting tasks: Effects of load weight and load knowledge

Load transfer during lifting leads to increased postural perturbations that may compromise postural stability, so lifting is an occupational task associated with high fall risk. This study aimed to gain improved knowledge about fall risk in lifting tasks. The effects of both load weight and load knowledge were examined. Load weight was set at three levels according to individuals’ maximum acceptable lifting capacity. Unlike previous studies, load knowledge was set by considering load material fragility. Twenty-four male participants were involved in the experimental study, in which they were instructed to perform both symmetric and asymmetric lifting tasks under conditions defined by various combinations of load weight and load knowledge. Fall risk was assessed by using measures accounting for postural stability and risk of slips. The results showed that when being defined near individuals’ maximum acceptable lifting capacity, increased lifting load weight not only improved postural stability in the rising phase of lifting, but also increased the risk of slips. These findings suggest that improved postural stability due to increased load weight in the rising phase could be a compensatory postural control strategy for the increased risk of slips so as to maintain balance and avoid the occurrence of a potential fall. We also found that load knowledge of fragility and weight may not contribute to fall risk reduction during lifting. The findings obtained from the present study are useful for practitioners to design safe lifting tasks.

Improvement of the airfoil lift and drag characteristics using plasma-efficient flow control

Flow control is studied to improve the aerodynamic performance of an aerofoil. A strategy for maintaining the near-wall flow structure with a given spatial scale, developed within the framework of interdisciplinary research, is used. The proposed active flow control method is based on the application of spanwise arrays of mechanical, thermal, or plasma vortex generators. The latter are found most versatile and efficient for the formulated goal. Aerodynamic coefficients measured in the specified wind tunnel are discussed for the 12.5% supercritical airfoil model. The model is controlled by the spanwise array of pulsating high-voltage plasma discharges. This multi-actuator system provides a sufficient number of control parameters such as pulse duration and repetition rate, the distance between the neighboring actuators (space scale of generated disturbances), and the plasma array location along the airfoil chord. Measurements in a range of Reynolds numbers of Rec=(3-7)x105 showed growth of a maximal lift coefficient CLmax up to 10% and the stall angle by 1.5°-3.5° accompanied by drag reduction up to 7%.

Biomechanical Characterization of the CrossFit® Isabel Workout: A Cross-Sectional Study

A cross-sectional study was conducted to biomechanically characterize Isabel’s workout (30 snatch repetitions with 61 kg fixed weight), focusing on eventual changes in knee, hip and shoulder angles. A three-dimensional markerless motion capture system was used to collect data from 11 highly trained male crossfitters along the Isabel workout performed at maximal effort. The routine was analyzed globally and in initial, middle and final phases (10, 20 and 30 repetitions, respectively). Lift total time increased (1.51 ± 0.18 vs. 1.97 ± 0.20 s) and maximal lift velocity (2.64 ± 0.12 vs. 2.32 ± 0.13 m/s) and maximal lift power (15.58 ± 2.34 vs. 13.80 ± 2.49 W/kg) decreased from the initial to final phases, while the time from lift until the bar crossed the hip and shoulder (34.20 ± 4.00 vs. 27.50 ± 5.10 and 39.70 ± 16.80 vs. 30.90 ± 13.90%) decreased along the Isabel workout. In addition, a decrease in hip flexion was observed during the last two phases when the bar crosses the knee (62.62 ± 24.80 vs. 53.60 ± 19.99°). Data evidence a decrease in the power profile and a change in hip flexion throughout the Isabel workout, without compromising the other joints.

Numerical Study of Laminar Flow and Vortex-Induced Vibration on Cylinder Subjects to Free and Forced Oscillation at Low Reynolds Numbers

In this study, we aimed to numerically investigate the 2D laminar flow over a cylindrical body and performed vortex-induced vibration analyses on a circular cylinder of unit radius placed in a channel, with the cylinder assumed to be fixed. The cases of a cylinder under forced oscillation and three different scenarios of a freely oscillating cylinder were analyzed. The fluid domain dynamics were governed by the incompressible Navier–Stokes equations; however, the structural field was described using nonlinear elastodynamic equations. Fluid and solid domains were discretized with the finite volume method (FVM) in space and time. Predictions of hydrodynamic forces, namely lift and drag terms, were determined for each scenario. An increase in the Reynolds number caused an exponential increment in the lift force. In the case of a stabilized flow, the collective decrease in stiffness and damping decreased the maximal drag and lift factors. Furthermore, it was noticed that the lift factor was minimally altered by variations in damping and stiffness in comparison with the change in the drag factor. From these observations, it appears that the lift factor probably correlates with the cylinder’s structure and fluid properties.

Analysis of structures and movement parametres of self-climbing platforms and development prospects

Introduction. For high-rise building construction self-climbing platforms based on hydraulic drive are used, lifting the formwork for monolithic structures. These lifting mechanisms differ in structures, characteristics and parameters. There is a need to introduce high-tech equipment in the industry. To create self-climbing platforms for high-rise construction, it is necessary to conduct research in the field of operation of lifting vehicles.Materials and methods. Platforms based on climbing profile for the analysis were used. The design features of the specified type of platforms were considered. The main parameters were speed of lifting, maximum lifting height and load capacity.Results. Graphical data on the main structural elements and the lifting process were obtained the specified type of platforms. Graphical data on hydraulic system is provided and the mechanism of movement is considered in detail. The basic formulas for determining the platform lifting speed and maximum load capacity required for the choosing of specified lifting vehicles.Discussion and conclusion. Existence of factors affecting the lifting speed of platforms and their maximum load capacity provides grounds for the development of a method for calculating and designing the considered transport and technological equipment in Russian Federation. One of the ways to develop this lifting equipment is integration of accessory mechanisms into their structure for fulfilling additional works during the construction of high-rise buildings, in this way forming a single transport and technological complex.

Design and Scalable Fast Fabrication of Biaxial Fabric Pouch Motors for Soft Robotic Artificial Muscle Applications

Soft pouch motors, engineered to mimic the natural movements of skeletal muscles, play a crucial role in advancing robotics and exoskeleton development. However, the fabrication techniques often involve multistage processes; they lack soft sensing capabilities and are sensitive to cutting and damage. This work introduces a new textile‐based pouch motors with the capacity for biaxial actuation and capacitive sensory functions, achieved through the application of computerized knitting technology using ultrahigh molecular weight polyethylene yarn (Spectra) and conductive silver yarns. This method enables the rapid and scalable mass fabrication of robust pouch motors. The resulting pouch motors exhibit maximum lifting capacity of 10 kg, maximum contraction of 53.3% along the y‐axis, and transverse extension of 41.18% along the x‐axis at 50 kPa pressure. Finite element analysis closely matches the experimental data. The capacitance signals in relation to contraction motion are well suited for detecting air pressure levels and hold promise for applications requiring robotic control. Notably, it effectively elevates an ankle joint simulator at a 20° angle, highlighting its potential for applications such assisting individuals with foot drop. This study presents a practical demonstration of the soft ankle exosuit designed to provide lifting support for individuals facing this mobility challenge.

Assisted Tea Leaf Picking: The Design and Simulation of a 6-DOF Stewart Parallel Lifting Platform

The 6-DOF Stewart parallel elevation platform serves as the platform for mounting the tea-picking robotic arm, significantly impacting the operational scope, velocity, and harvesting precision of the robotic arm. Utilizing the Stewart setup, a parallel elevation platform with automated lifting and leveling capabilities was devised, ensuring precise halts at designated elevations for seamless harvesting operations. The effectiveness of the platform parameter configuration and the reasonableness of the posture changes were verified. Firstly, the planting mode and growth characteristics of Yunnan large-leaf tea trees were analyzed to determine the preset path, posture changes, and mechanism stroke of the Stewart parallel lifting platform, thereby determining the basic design specifications of the platform. Secondly, a 3D model was established using SolidWorks, a robust adaptive PD control model was built using MATLAB for simulation, and dynamic calculations were carried out through data interaction in Simulink and ADAMS. Finally, the rationality of the lifting platform design requirements was determined based on simulation data, a 6-DOF Stewart parallel lifting platform was manufactured, and a motion control system was built for experimental verification according to the design specifications and simulation data. The results showed that the maximum deviation angle around the X, Y, and Z axes was 10°, the maximum lifting distance was 15 cm, the maximum load capacity was 60 kg, the platform response error was within ±0.1 mm, and the stable motion characteristics reached below the millimeter level, which can meet the requirements of automated operation of the auxiliary picking robotic arm.

A Study on the Ultimate Span of a Concrete-Filled Steel Tube Arch Bridge

In order to study the ultimate span of a concrete-filled steel tube (CFST) arch bridge, taking the structural strength, stiffness, and stability as the limiting conditions, the finite element analysis method is adopted to carry out research on the influence law of a single parameter of the pipe diameter, wall thickness, and cross-section height on the ultimate span of the arch axial shape. The result is used as a sample point to determine the ultimate span of the CFST arch bridge under multifactor coupling based on the response surface method. The finite element method is used to check the strength, stiffness, stability, number of segments and maximum lifting weight, steel content rate, and steel pipe concrete constraint effect coefficient of the CFST arch bridge under the ultimate span diameter. The results show that, when analyzed using a single parameter, the ultimate span diameter of the CFST arch bridge increases with the increase in the steel pipe diameter and the cross-section height, and then decreases. Moreover, it increases with the increase in the wall thickness of the steel pipe, and the CFST arch bridge reaches the ultimate span with the increase in the steel pipe wall thickness. When the pipe diameter is 1.38 m, the CFST arch bridge reaches the ultimate span; according to a multi-parameter coupling analysis, when the pipe diameter is 1.49 m, wall thickness is 37 mm, and cross-section height is 17 m, the CFST arch bridge reaches the ultimate span of 821 m, which meets all of the limiting conditions, and, at this point, the arch axial coefficient is 1.2. The results of the finite element calculation show that the structural strength, prior to the stiffness, stability, and other limitations, just reaches the critical value of the limiting conditions.

Experimental study of aerodynamic coefficients of a combined blade

Magnus wind turbines have a number of advantages in the form of electricity generation at low wind values, ranging from 3-4 m/s. However, at high speeds around the existing blades of wind turbines, there is a phenomenon of separation of vortices, which entails the destruction of the structure, as well as an increase in drag. Based on this, an urgent issue is the regulation of the flow around cylindrical bodies, along with a decrease in drag force. The novelty of the work is the elimination of vortices, as well as their control, by adding a fixed blade to the cylinder. Authors of the article for this purpose created a mock-up of the cylinder blade with a fixed blade. A number of experimental studies were carried out to determine the aerodynamic forces and coefficients depending on the angle of inclination with respect to the incoming flow at U = 5 m/s. It was found that at an angle of inclination of 0° and 180°, the combined blade has a maximum lifting force of 2.7 N and 2.75 N, respectively. It is determined that at these angles, the drag force is the lowest and is 1.26 N and 1.08 N.

Two-year clinical outcomes and complication rates in anatomic and reverse shoulder arthroplasty implanted with Exactech GPS intraoperative navigation.

We compared the 2-year clinical outcomes of both anatomic and reverse total shoulder arthroplasty (ATSA and RTSA) using intraoperative navigation compared to traditional positioning techniques. We also examined the effect of glenoid implant retroversion on clinical outcomes. In both ATSA and RTSA, computer navigation would be associated with equal or better outcomes with fewer complications. Final glenoid version and degree of correction would not show outcome differences. A total of 216 ATSAs and 533 RTSAs were performed using preoperative planning and intraoperative navigation with a minimum of 2-year follow-up. Matched cohorts (2:1) for age, gender, and follow-up for cases without intraoperative navigation were compared using all standard shoulder arthroplasty clinical outcome metrics. Two subanalyses were performed on navigated cases comparing glenoids positioned greater or less than 10° of retroversion and glenoids corrected more or less than 15°. For ASTA, no statistical differences were found between the navigated and non-navigated cohorts for postoperative complications, glenoid implant loosening, or revision rate. No significant differences were seen in any of the ATSA outcome metrics besides higher internal and external rotation in the navigated cohort. For RTSA, the navigated cohort showed an ARR of 1.7% (95% CI 0%, 3.4%) for postoperative complications and 0.7% (95% CI 0.1%, 1.2%) for dislocations. No difference was found in the revision rate, glenoid implant loosening, acromial stress fracture rates, or scapular notching. Navigated RTSA patients demonstrated significant improvements over non-navigated patients in internal rotation, external rotation, maximum lifting weight, the Simple Shoulder Test (SST), Constant, and Shoulder Arthroplasty Smart (SAS) scores. For the navigated subcohorts, ATSA cases with a higher degree of final retroversion showed significant improvement in pain, Constant, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), SST, University of California-Los Angeles shoulder score (UCLA), and Shoulder Pain and Disability Index (SPADI) scores. No significant differences were found in the RTSA subcohort. Higher degrees of version correction showed improvement in external rotation, SST, and Constant scores for ATSA and forward elevation, internal rotation, pain, SST, Constant, ASES, UCLA, SPADI, and SAS scores for RTSA. The use of intraoperative navigation shoulder arthroplasty is safe, produces at least equally good outcomes at 2 years as standard instrumentation does without any increased risk of complications. The effect of final implant position above or below 10° of glenoid retroversion and correction more or less than 15° does not negatively impact outcomes.

Forklift selection by multi-criteria decision-making methods

A forklift is a very important and common equipment for transporting materials in many different locations such as workshops, warehouses, supermarkets, etc. This equipment has the effects of reducing labor consumption of workers, ensuring the safety of goods and improving labor efficiency. That is why forklift selection is very important. In order to choose a forklift, it is necessary to consider many parameters such as lifting capacity, lifting height, travel speed, safety level, price, maintenance cost, level of impact on the environment, ease of use, etc. However, today there are many types of forklifts on the market, these forklifts have different specifications and prices, making it difficult for shoppers to choose a product in many available types. This study has applied multi-criteria decision-making (MCDM) methods for forklift selection. Two MCDM methods having been used are the COCOSO (Combined Compromise Solution) method and PIV (Proximity Indexed Value) method. Two different methods having also been used to calculate the weights for the criteria are the ENTROPY method and MEREC (Method based on the Removal Effects of Criteria) method. The selection of the best type of forklift applies to the six available types. Six criteria having been used to describe each alternative are lifting height, maximum lifting height, minimum lifting height, fork length, fork width, and price. Each MCDM method will be used in combination with two weight methods. Thus, the ranking results of forklifts are shown in four different series of numbers. An amazing result has occurred that the best and worst forklifts have been consistently determined to be the same in all cases examined. This is the outstanding advantage of the COCOSO and PIV methods compared to other MCDM methods.

Performance Analysis of Motorized Object Lifting Toggle Jack

This study seeks to develop a motorized car jack with maximum lifting capacity of 1.5 tons. The principle of the existing car jack was modified by making adjustments and using a prime mover which is the electric motor to control the lifting operation of the jack. The design incorporates an electric motor that is powered by a 12-volt battery of a small vehicle and the device is connected through a cigarette lighter adapter in the vehicle. The common challenge with the currently available car jacks on the market is that they are manually operated and need a substantial amount of physical effort is required to lift the vehicle. In this work, human effort was eliminated in raising the jack by the use of the torque generated by the motor as it rotates. The use of long cablings to control the motorized operation assists the jack to be safe to use as the operator can use the jack in a comfortable position and as far away from the vehicle as possible. The performances of the machine at different loads were calculated. The approximate values and graphical relationships were established. Using MS Excel. It was established that, the machine had efficiency of about 53%. The investigation revealed that the minimal efficiency was as a result of the great frictional forces between the screw and the threaded base required to be overcome as well as the capacity of the DC motor and gear system.

Effect of pitching angle, pitch-pivot-point, blade camber and deflected sharp leading edge on performance and vortical flows of reversed pitching airfoils

The goal of the present work is to investigate the influence of several parameters on the performance and flow structures of reversed pitching airfoils. Firstly, the effect of the turbulence model is evaluated, and the results show that the SST γ−Re˜θt transition model has a better prediction in the instantaneous lift coefficient of a reversed pitching airfoil and the transition locations of a stationary airfoil. Then, effects of the pitching angle, pitch-pivot-point, blade profile and morphed leading edge with various deflection angles and positions on the performance, unsteady vortical flow, near-wall transition and trajectory of main vortices, are analyzed. The main results show that both the mean pitching angle and pitching amplitude have the impact on the vortical flows, but depends on the reduced frequency. Then, the delayed flow structure by shifting the pitch-pivot-point from the leading edge (LE) to trailing edge (TE) can be explained by the distribution of the effective attack-of-angle. Moreover, the symmetrical, asymmetrical and inverse asymmetrical airfoils have great effect on the first (FMLC) and second maximal lift coefficients (SMLC). Finally, upward deflected LE decreases the negative lift coefficient while downward morphed LE improves it considerably due to the geometry curvature leading to the large flow separation. In addition, it is observed that the generation of vortices is earlier when the deflection position close to the middle surface. It is believed that this work can provide some guidelines to have a better design of energy devices with oscillating airfoils/hydrofoils.

LNG Type C, Cylindrical Weight Design Limitation Based on Shipbuiding Facilities

Supporting climate change mitigation and sustainable energy due to its ability to reduce CO2, Liquefied Natural Gas (LNG) considered as promising alternative fuel. In a particular small market with LNG demand between 2,500 m3 to 7,500 m3, utilization of LNG type-C, cylindrical tanks are compatible to use in small-scale LNG carrier. In order to overcome these challenges, Indonesian industry need to design the tank’s volume and weight requirements.while also taking into account the capabilities of the shipbuilding facilities. The weight of the tank, which comprises the weight of the outer tank and dished end, are the decision variable in the approach for weight estimation analysis, which carried by using using extrapolation to search optimum diameter and length of the tank The objective function is maximization of the tank capacity. The capability of the lifting equipment in the shipyard is the limitation used in this paper. This research data is based on the shipyard capability of PT. PAL Indonesia, PT. Dok dan Perkapalan Kodja Bahari (Persero), PT. Industri Kapal Indonesia, and PT. Batamec Shipyard. Result obtained that maximum volume of 5,663.369 m3 LNG type C, weight about 450.671 tons with maximum crane lifting capacity in shipyard are 500 tons

On the Lift, Related Privacy Measures, and Applications to Privacy–Utility Trade-Offs

This paper investigates lift, the likelihood ratio between the posterior and prior belief about sensitive features in a dataset. Maximum and minimum lifts over sensitive features quantify the adversary's knowledge gain and should be bounded to protect privacy. We demonstrate that max- and min-lifts have a distinct range of values and probability of appearance in the dataset, referred to as lift asymmetry. We propose asymmetric local information privacy (ALIP) as a compatible privacy notion with lift asymmetry, where different bounds can be applied to min- and max-lifts. We use ALIP in the watchdog and optimal random response (ORR) mechanisms, the main methods to achieve lift-based privacy. It is shown that ALIP enhances utility in these methods compared to existing local information privacy, which ensures the same (symmetric) bounds on both max- and min-lifts. We propose subset merging for the watchdog mechanism to improve data utility and subset random response for the ORR to reduce complexity. We then investigate the related lift-based measures, including ℓ1-norm, χ2-privacy criterion, and α-lift. We reveal that they can only restrict max-lift, resulting in significant min-lift leakage. To overcome this problem, we propose corresponding lift-inverse measures to restrict the min-lift. We apply these lift-based and lift-inverse measures in the watchdog mechanism. We show that they can be considered as relaxations of ALIP, where a higher utility can be achieved by bounding only average max- and min-lifts.

STUDY OF THE DURABILITY OF THE BEARING ELEMENTS OF THE LIFTING PART OF THE DRILLING RIG

This article discusses the mode of operation of the hoist rope. The work of a steel rope in the talus system of drilling rigs is considered, taking into account the main wear factors. The memodics of the training of the hoisting ropes is proposed. It is shown that the regularity of the distribution of the number of rope bending cycles on pulleys and drum allows us to develop recommendations for drillers to limit the maximum lifting height of the talus block, to develop a methodology for optimal working out (bypasses) of the talus rope during the well wiring and to make a program for working out the rope based on the fatigue nature of its wear.

The Spiral Lift: A Novel Twist on Body Contouring

Abstract Goals/Purpose Thigh lifts historically have been performed using a vertical excision to correct the horizontal laxity.1However, this leaves an unsightly scar when wearing shorts or a bikini bottom. More recently the horizontal scar saving thighplasty has been described, but this only addresses a limited medial portion of the thigh laxity.2While plastic surgeons perform abdominoplasty concurrently with medial thigh lifts,3 there is no described technique of this type of spiral lift in the literature. The spiral lift does not use liposuction of the medial thighplasty portion of the procedure as is used in many of the published techniques.4 Moreover, compared to other described horizontal thigh lift techniques, which use a much smaller horizontal incision,5 the spiral lift extends this incision in the groin crease and into the inferior gluteal crease, resulting in a longer but very well hidden incision. This provides maximal lift of the entire thigh while avoiding a vertical scar. Our goal was to develop a technique to lift the medial and lateral aspect of the leg and the buttock skin while also minimizing visible scarring. Methods/Technique The lower abdominoplasty/belt lipectomy incision is designed in the pre-operative area such that the post-operative incision will be hidden in a pair of underwear of choice. The thighplasty incisions are designed in the groin crease, continuing into the lower abdominoplasty incision, and extend posteromedially around into the inferior gluteal crease. A pinch test is used to determine the appropriate amount of tissue that can be excised. The patient is intubated on the stretcher, then flipped into the prone position on an OR bed. Excision is performed to the level of the thoracolumbar fascia on the back and Scarpa’s fascia for the thighs to avoid the posterior cutaneous nerve. Two drains are left in the back. Following closure, the patient is flipped supine onto a second OR bed. A standard abdominoplasty is then performed in continuation with the back incision to complete the belt lipectomy. The anterior medial thigh excision is again performed at the level of Scarpa’s fascia, staying superficial in the region of the femoral vessels and lymphatics. Two drains are placed anterior in the abdomen. Results/Complications A total of 12 pts have undergone a full belt lipectomy with the spiral lift thighplasty since it first was performed in July 2019. This technique has shown good cosmetic results (Figures 1&2), providing a circumferential vertical lift of the buttock and entire thigh while also addressing the abdomen and back. We have had good success in both men and women. This procedure is especially beneficial for massive weight loss patients, but we have also done the spiral thigh lift with abdominoplasties not requiring circumferential body lift. Five patients also underwent additional concurrent procedures involving the breast (mastopexy, augmentation, etc). Some patients had same day surgery (7), while five were observed overnight. The patients do tend to get some mild swelling of the mons. Scrotal swelling can be minimized with scrotal elevation and compression. Three patients had dehiscence of the thigh wounds, two of which were minor and were managed with dressing changes. One was caused by a fall at home and required return to the operating room for repair, but also had subsequent dehiscence requiring dressing changes. This was one of two patients that were re-admitted following the procedure, the other being a patient admitted for UTI sepsis 10 days after surgery. Forty-two percent of patients have had minor revisions following the procedure, 80% of which are performed concurrently with another primary surgery (eg. brachioplasty, cervicoplasty). One patient experienced transient lymphedema of the bilateral thighs. We have experienced no major infections. Some patients have experienced descent of the anterior medial thigh incision, visible in bikini bottoms. Conclusion The spiral lift is a technique that can successfully achieve a full body lift and address the thigh laxity circumferentially while completely hiding the scars in the underwear lines or natural skin creases.

Research on the Lifting Forces of Industrial Plastic Vacuum Cups

Industrial vacuum cups are used for lifting, holding and moving a wide variety of automated applications for handling semi-finished products and parts made of a wide range of materials - metal, glass, plastic, paper, wood, etc. and are used in a variety of industries. This paper presents some of the authors theoretical and experimental research on the maximum lifting force that different types of vacuum cups can achieve. The study was carried out on the basis of sizing recommendations made by manufacturers and dealers of these types of vacuum cups. The specially designed experimental stand was installed on the universal material testing machine LBG 100 kN and allowed the practical determination of these lifting forces provided by various types of industrial vacuum cups. Lifting force measurements were carried out with the AXIS FB 1k digital dynamometer attached to the machine. Vacuum cups of 3 different shapes and made of 3 different materials were used, using different vacuum depressions - 0.3 bar, -0.5 bar, -0.7 bar and -0.9 bar. The research aimed to determine by measurement the maximum lifting force of these types of vacuum cups applied to steel parts. The results obtained for these forces were compared with the calculated theoretical values, with the manufacturer�s recommended dimensioning values, and comparative conclusions were also drawn on the maximum lifting force provided by the different types of industrial vacuum cups studied.

Skin Application of Menthol Enhances Maximal Isometric Lifting Performance.

Abstract Over, DM, Arjomandkhah, N, Beaumont, JD, Goodall, S, and Barwood, MJ. Skin application of menthol enhances maximal isometric lifting performance. J Strength Cond Res 37(3): 564–573, 2023—Topical application of menthol to the skin improves perception (i.e., makes subjects feel cooler) and changes submaximal neuromuscular recruitment facilitating force generation. We explored the effect of menthol (0.2% concentration; sprayed on the legs), on perception and maximal, dynamic (DLT) and isometric (IMLT) (weight) lifting tasks. Nine resistance-trained male subjects (mean ± SD: 24 ± 5 years; 75.7 ± 8.8 kg; 174 ± 10 cm; 5 repetition maximum deadlift [5RM] 132.3 ± 28.5 kg) were tested using a repeated measures design; we hypothesized that performance would improve. Before completing the DLT (i.e., deadlift performance 75% 1RM) and a midthigh pull dynamometer IMLT, subjects were sprayed with (∼125 ml) of menthol or control spray. Performance, electromyography (root mean squared [rmsEMG], rectus femoris [RF], biceps femoris [BF], and medial gastrocnemius [MG]), perceptions (leg thermal sensation [TSlegs] and comfort [TClegs] and perceived exertion [RPE] and readiness to train), heart rate, and skin temperature were measured. Data were compared using analysis of variance (effect size ) and t test to a 0.05 alpha level supported by Bayesian analysis. Dynamic lifting task performance was unchanged, although BF rmsEMG was higher (i.e., greater muscle activation in final [10th] repetition). Isometric lifting task force production was higher in the menthol spray (148 ± 30 kgf) condition (control spray 140 ± 30 kgf; p = 0.035, = 0.444) with corresponding higher rmsEMG (BF 3.8 ± 1.46 vs. control spray 2.9 ± 0.34 V; p = 0.049, = 0.403). TSlegs was lower after menthol spray before IMLT; subjects felt slightly cool. Menthol spray enhances isometric weightlifting performance with corresponding changes in neuromuscular activity, partially supporting our hypothesis.

Experimental and Numerical Investigation of Cavity Structure Forced Water Exit from Calm Water at Constant Lifting Velocity

In marine engineering, the installation of structures inevitably involves the process of water exit. This paper studies the vertical force, the shape of the free surface, and the evolution of the water entrained in a cavity in the process of lifting a structure, so as to provide guidance for practical engineering operations. Using a 1:8 experimental model, this paper derives the governing equations based on the Reynolds-averaged Navier–Stokes approach and uses the volume of fluid method to capture the shape change of the free surface. The vertical forces obtained at different lifting speeds are found to be in good agreement with the results of previous model tests. The results show that the numerical simulation method and mesh generation described in this paper can simulate the changes in the physical quantities associated with the structure in the process of water exit. The vertical force on the structure increases nonlinearly as the lifting speed rises, and the maximum lifting speed is conservatively estimated to be 0.034 m/s using the Det Norske Veritas recommended method. The maximum vertical force occurs as the whole structure leaves the water. The water entrained in the structure is mainly located at the sides and bottom. The lifting velocity plays an important role in the water exit process. The water exit force first increases and then decreases to a stable value as the lifting velocity increases, while the maximum water exit force increases nonlinearly.