Output Power Performance Research Articles

A Nonlinear Model of RF Switch Device Based on Common Gate GaAs FETs

ABSTRACTThis paper presents a novel method for nonlinear modeling GaAs field‐effect transistors (FETs) in a common gate (CG) configuration, which is crucial for the effective design and thorough assessment of RF switch circuits. By focusing solely on a CG‐based GaAs FET for RF switch device characterization and modeling, the modeling process is streamlined compared to traditional methods that involve both CG and common source (CS) devices. The direct measurement of both DC and RF characteristics using the CG device enhances the accuracy of model parameter extraction. This approach ensures consistency in model and simulation applications as the CG topology aligns with devices commonly found in RF switch circuits. Moreover, to enhance predictive accuracy regarding the dispersion effect, an improved equation of drain‐source current has been incorporated. The empirical validation of the model reveals good agreements in terms of insertion loss, isolation, and output power performance for the CG GaAs FET device, including a wide band single‐pole double‐throw (SPDT) switch Monolithic Microwave Integrated Circuit (MMIC).

The effect of cycling shoe sole stiffness on sprint power output

Competitive and recreational cyclists use stiff-soled shoes that firmly attach to ‘clipless’ pedals. When compared to very flexible running shoes, very stiff cycling shoes with clipless pedals enhance power output during sprint cycling. However, a recent study showed no difference in power output or sprint performance between commercially available cycling shoes that span a range of longitudinal bending stiffnesses (∼200 to 500 N·m/rad). Thus, we sought to identify the likely range of sole stiffnesses below 200 N·m/rad over which reduced cycling shoe sole stiffness begins to decrease maximal power output. We measured the mechanical power outputs of 25 road cyclists during maximal sprints wearing shoes with identical uppers but with three different sole stiffnesses. Each participant completed nine 50 m sprints (three trials for each shoe) on a road with a steady, uphill grade of 9.1%. The three shoe sole conditions were: injected nylon (longitudinal bending stiffness 194 N·m/rad), moderate stiffness thermoplastic polyurethane (medium TPU) (43 N·m/rad), and low stiffness TPU (soft TPU) (9 N·m/rad) all ridden with the same clipless pedals. Stiffness was quantified using a simple testing apparatus. Power output decreased below the sole stiffness of ∼200 N·m/rad but only moderately. Maximal 1 s crank power (Pmax1) decreased −3.1% (ES = −0.59, p = 0.020) from Nylon to medium TPU and then further decreased −2.4% (ES 16 = −0.50, p = 0.054) from medium TPU to soft TPU. Interpolating our results suggests just a ∼1% loss in Pmax1 at a sole stiffness of 100 N·m/rad. Within reasonable limits, cycling shoe sole stiffness has only a small effect on power output.

Effect of Thermal Environment on Heat Transfer Mechanism of Solar-Powered Balloon

Solar energy units, as an ideal alternative, can be supplied to the balloons by mounting them over the envelope of the balloon. To avoid superheating and superpressure, the solar-powered balloon’s thermal efficiency should be controlled. In the current research, the thermal model of a solar-powered zero-pressure balloon has been built up and simulated in FORTRAN via iterative techniques and validated with published experimental data. The simulation of stratospheric solar-powered balloon flight has been carried out in real seasonal atmospheric conditions. The temperature variation of solar panels, interior helium, and balloon envelope material has been observed and compared with the unpowered balloon in winter and summer atmospheric conditions. The output power performance of the photovoltaic panel placed over the balloon with and without thermal effect has been reported. Furthermore, the characteristic length, angle, and area of the solar panel effects on photovoltaic panel temperature and output power are discussed in detail. The maximum temperature of the helium and envelope of the solar-powered balloon is obtained as 350.03 K and 351.19 K, respectively, and is notable in the summer solstice compared with the unpowered balloon. This research would help design the energy unit of the stratospheric balloon for long endurance.

A V-band injection locking tripler with 26.8% locking range and 7.3-dBm output power in 65 nm CMOS

With a 65-nm CMOS process, a V-band wideband injection locking (IL) frequency tripler is proposed by cascading a multiplier and a driver amplifier stage. Concerning high output power and efficiency performance over a wideband locking range (LR), two transformer-based IL topologies are analyzed in the multiplier and driver stages, in which the cross-coupled pair is connected at the input and output ports of the transformer, respectively. Moreover, the active device is carefully designed in terms of the operating point of the harmonic generator and device sizing in the driver amplifier stage. With measurements, the proposed tripler achieves a maximum measured output power of 7.3 dBm with 22.4% output-to-DC power efficiency and 26.8% LR from 50.4 to 66 GHz. Including the output driver amplifier, the IL tripler consumes 24 mW DC power. The measured fundamental and 2nd-harmonic rejection ratios (HRR) are both better than 30 dBc, while the measured phase noise (PN) degradation is in close agreement with the theoretical value.

Reliability Enhancement of a Double-Switch Single-Ended Primary Inductance–Buck Regulator in a Wind-Driven Permanent Magnet Synchronous Generator Using a Double-Band Hysteresis Current Controller

The wind power exchange system (WECS) covered in this paper consists of a voltage source inverter (VSI), a DSSB regulator, and an uncontrolled rectifier. An AC grid or a heavy inductive or resistive load (RL) can be supplied by this system. The DSSB is a recently developed DC-DC regulator consisting of an improved single-ended primary inductance regulator (SEPIC) followed by a buck regulator. It has a peak efficiency of 95–98% and a voltage gain of (D (1+D)/(1−D). where D is the regulator transistor’s on-to-off switching ratio. The proposed regulator improves the voltage stability and MPPT strategy (optimal or maximum power-point tracking). The combination of the DSSB and the proposed regulator improves the efficiency of the system and increases the power output of the wind turbine by reducing the harmonics of the system voltages and current. This method also reduces the influence of air density as well as wind speed variations on the MPPT strategy. Classical proportional–integral (PI) controllers are used in conjunction with a vector-controlled voltage source inverter, which adheres to the suggested DSSB regulator, to control the PMSM speed and d-q axis currents and to correct for current error. In addition to the vector-controlled voltage source inverter (which follows the recommended DSSB regulator), classical proportional–integral controllers are used to regulate the PMSM speed and d-q axis currents, and to correct current errors. In addition, a model Predictive Controller (PPC) is used with the pitch angle control (PAC) of WECS. This is done to show how well the proposed WECS (WECS with DSSB regulator) enhances voltage stability. A software-based simulation (MATLAB/Simulink) evaluates the results for ideal and unoptimized parameters of the WT and WECS under a variety of conditions. The results of the simulation show an increase in MPPT precision and output power performance.

Multifunctional Nano‐Conductive Hydrogels With High Mechanical Strength, Toughness and Fatigue Resistance as Self‐Powered Wearable Sensors and Deep Learning‐Assisted Recognition System

AbstractHigh mechanical strength, toughness, and fatigue resistance are essential to improve the reliability of conductive hydrogels for self‐powered sensing. However, achieving mutually exclusive properties simultaneously remains challenging. Hence, a novel directed interlocking strategy based on topological network structure and mechanical training is proposed to construct tough hydrogels by optimizing the network structure and modulating the orientation of molecular chains. Combining Zn2+ crosslinked cellulose nanofibers (CNFs) and a polyacrylamide‐poly(vinyl alcohol) double‐network, the unique interlocked‐network structure exhibits an enhanced toughening effect due to hydrogen bonding and metal‐ligand interactions. The aligned nanocrystalline domains achieved by training further contribute to an increase in the toughness and fatigue thresholds. This innovative approach synergistically enhances the mechanical properties of the nano‐conductive hydrogel, achieving a maximum tensile strength of 4.98 MPa and a toughness of 48 MJ m−3. Notably, the CNFs template with anchored polyaniline, when oriented through mechanical training, forms a unique directional conductive pathway, which significantly enhances the power output performance. Besides, a motion recognition system based on a self‐powered sensing device is designed with the assistance of deep learning techniques to accurately identify human motion behaviors. This work showcases a potentially transformative flexible electronic material for self‐powered sensing systems and intelligent recognition systems.

Enhancing Power and Thermal Gradient of Solar Photovoltaic Panels with Torched Fly-Ash Tiles for Greener Buildings

Solar photovoltaic (PV) panels that use polycrystalline silicon cells are a promising technique for producing renewable energy, although research on the cells’ efficiency and thermal control is still ongoing. This experimental research aims to investigate a novel way to improve power output and thermal performance by combining solar PV panels with burned fly-ash tiles. Made from burning industrial waste, torched fly ash has special qualities that make it useful for architectural applications. These qualities include better thermal insulation, strengthened structural integrity, and high energy efficiency. Our test setup shows that when solar PV panels are combined with torched fly-ash tiles, power generation rises by 7% and surface temperature decreases by 3% when compared to standard panels. The enhanced PV efficiency is ascribed to the outstanding thermal insulation properties of fly ash tiles and their capacity to control panel temperature. To ensure longevity and safety in building applications, the tiles employed in this study had a water absorption rate of 5.37%, flexural strength of 2.95 N/mm2, and slip resistance at 38 km/h. Furthermore, we find improved structural resilience and lower cooling costs when up to 30% of the sand in floor tiles is replaced with torched fly ash, which makes this method especially appropriate for sustainable buildings. Key performance indicators that show how effective these tiles are in maximizing energy use in buildings include thermal emissivity (0.874), solar reflectance (0.8), and solar absorption (0.256). While supporting more ecofriendly building techniques, this study highlights the advantages of utilizing burned fly ash in solar PV systems: enhanced power generation and thermal comfort. The main results open a greater potential for fly ash use in different building materials. The use of torched fly ash in building materials enhances thermal insulation and structural integrity while lowering cooling costs, making it an ideal choice for eco-friendly construction and highlighting the potential for further research into environmentally responsible, energy-efficient solutions.

Multilayer Electrode Strategy Shorten Thermal Charging Time and Boost Energy Output in Gelatin‐Based i‐TE Cells

AbstractGel‐based ionic thermoelectric (i‐TE) cells provide alternative thermal energy harvesting from the environment, showing obvious advantages in voltage matching for self‐powered Internet‐of‐Things (IoT) sensors. However, the gel‐based i‐TE cells always suffer a long thermal charging time and poor output power performance. Herein, a multilayer electrode engineering strategy is proposed from the device‐design level, aiming to decrease the ions' diffusion distance, increase the electrode surface area, and facilitate the ions' reaction and recovery process. The thermal charging time is shortened from 27 to 8 min as the electrode layers increase from 2 to 8. An ultrahigh instantaneous power density of 15.8 mW m−2 K−2 and 2 h output energy density (E2h) of 403 J m−2 are achieved in an 8‐layer electrode i‐TE cell. Finally, A flexible and wearable i‐TE device with 20 units is demonstrated to generate a remarkable voltage of 3.8 V and output power of 282 µW by harvesting the human body heat. This work provides a feasible and effective route to design the i‐TE device, hopefully promoting its practical power generation application.

Heat Pipe-Based Cooling Enhancement for Photovoltaic Modules: Experimental and Numerical Investigation

High temperatures in photovoltaic (PV) modules lead to the degradation of electrical efficiency. To address the challenge of reducing the temperature of photovoltaic modules and enhancing their electrical power output efficiency, a simple but efficient photovoltaic cooling system based on heat pipes (PV-HP) is introduced in this study. Through experimental and numerical investigations, this study delves into the temperature characteristics and power output performance of the PV-HP system. Orthogonal tests are conducted to discern the influence of different factors on the PV-HP system. The experimental findings indicate that the performance of the PV-HP system is superior to that of the single system without heat pipes. The numerical simulation shows the effects of system structural parameters (number of heat pipes, angle of heat pipe condensation section) on system temperature and power output performance. The numerical simulation results show that increasing the angle of the heat pipe condensation section and the number of heat pipes leads to a significant drop in system temperature and an increase in the efficiency of the photovoltaic cells.

Energy forecasting of the building integrated photovoltaic system based on deep learning dragonfly-firefly algorithm

Building integrated photovoltaic (BIPV) technology is an emerging technology that harnesses solar energy. The BIPV system enhances the energy consumer to energy production in modern buildings. The performance of the BIPV system varies depending on geographical location, seasonal conditions, and environmental parameters. The performance prediction of the building-integrated photovoltaic system plays a vital role in the energy forecast and consumption pattern. In this work, the performance of the BIPV system output power is predicted based on solar radiation, ambient temperature, and wind speed in hot and humid climatic conditions. The study proposes a new neural network method, long short-term memory (LSTM), with feature selection using the dragonfly (DF) and firefly algorithms(FF). The hybrid deep learning algorithm (LSTM-DF-FF) predicts the performance. The performance metrics are used to evaluate the performance of the model. When conditions are ideal, LSTM–FF–predictions DFs have a relative error of just 3.5 %. Network forecasts are less dependable and accurate on days with clouds and rain, with relative errors of 7.8 and 10.1 %, respectively. The LSTM–FF–DF model had the highest correlation in all conditions, with 0.997 in the absence of clouds and 0.991 under overcast.

A Novel Design Strategy for Cantilever Based MEMS Piezoelectric Vibration Energy Harvesters: FEM Parametric Analysis and Modeling

Vibration-based energy-harvesting (VEH) technology is a viable alternative power source that addresses the issue of battery capacity constraints in portable electronic devices. A novel design strategy for developing a piezoelectric vibrational energy harvester (PVEH) based on a microelectromechanical system (MEMS) is proposed in this paper. Through FEM simulation and analysis, a correlation between the proof mass coverage (PMC) and piezoelectric coverage (PEC) for energy harvesters with different beam geometries is developed. The results show that the output power and resonant frequencies of the energy harvester are strongly dependent on the amount of PMC, PEC, and beam geometry. The optimum piezoelectric layer length for a PVEH depends on the amount of PMC and geometry of the beam. Moreover, as the PMC increases, the output power is found to be increasing. The structure with 80% PMC provides maximum output power. Also, a trapezoidal beam will give a lower resonant frequency than a rectangular beam. Thus the optimum design methodology for a cantilever-based MEMS PVEH in a given layout is to select the trapezoidal-shaped beam with a PMC of 60% to 80% and piezoelectric layer length equal to the beam length. This method would provide optimised resonant frequency and output power performance. Additionally, an analytical model is developed for the optimised cantilever PVEH based on trapezoidal geometry, and the simulation findings are validated with the analytical results.

Experimental investigation of the effects of photovoltaic panels on efficiency cooling with nanofluids using both in‐pipe flow and fin

AbstractTemperature increases in photovoltaic (PV) panels are one of the primary issues preventing PV systems from being used extensively. When a photovoltaic module overheats, its output power performance drops by 0.4%–0.5% for every degree Celsius above its rated temperature. Lowering the operating temperature of the PV surface using a cooling medium is an efficient technique to increase electrical performance and decrease the rate of thermal degradation of a PV module. To prevent this performance loss, researchers have worked on cooling photovoltaic panels with fluids such as air, water, and nanofluids. In this study, the effects of cooling on photovoltaic panels with water and nanofluid were investigated. The experiment was carried out by fixing the pipe and fins to the back surface of the panel. Al2O3‐water and TiO2‐water nanofluids were used as working fluid due to their cost effectiveness. Nanofluids prepared in three different volumetric fractions (0.01%, 0.1%, and 1%), the current and voltage values obtained from the panels were recorded, and the panel efficiency was calculated. The experimental results showed that the cooling increased the panel voltage and decreased the current. The results indicated that using TiO2 nanofluid was more effective than Al2O3 nanofluid in terms of electrical efficiency. It was also found that the fluids prepared as 0.01% and 1% gave the most efficient results. It has been observed that it is possible to increase the panel efficiency by 8.32% by cooling the panel.

Performance Correction and Parameters Identification Considering Non-Uniform Electric Field in Cantilevered Piezoelectric Energy Harvesters.

In the current electromechanical model of cantilevered piezoelectric energy harvesters, the assumption of uniform electric field strength within the piezoelectric layer is commonly made. This uniform electric field assumption seems reasonable since the piezoelectric layer looks like a parallel-plate capacitor. However, for a piezoelectric bender, the strain distribution along the thickness direction is not uniform, which means the internal electric field generated by the spontaneous polarization cannot be uniform. In the present study, a non-uniform electric field in the piezoelectric layer is resolved using electrostatic equilibrium equations. Based on these, the traditional distributed parameter electromechanical model is corrected and simplified to a practical single mode one. Compared with a traditional model adopting a uniform electric field, the bending stiffness term involved in the electromechanical governing equations is explicitly corrected. Through comparisons of predicted power output with two-dimensional finite element analysis, the results show that the present model can better predict the power output performance compared with the traditional model. It is found that the relative corrections to traditional model have nothing to do with the absolute dimensions of the harvesters, but only relate to three dimensionless parameters, i.e., the ratio of the elastic layer's to the piezoelectric layer's thickness; the ratio of the elastic modulus of the elastic layer to the piezoelectric layer; and the piezoelectric materials' electromechanical coupling coefficient squared, k312. It is also found that the upper-limit relative corrections are only related to k312, i.e., the higher k312 is, the larger the upper-limit relative corrections will be. For a PZT-5 unimorph harvester, the relative corrections of bending stiffness and corresponding resonant frequency are up to 17.8% and 8.5%, respectively. An inverse problem to identify the material parameters based on experimentally obtained power output performance is also investigated. The results show that the accuracy of material parameters identification is improved when considering a non-uniform electric field.

Straw-derived macroporous biochar as high-performance anode in microbial fuel cells

Large-scale application of MFCs is limited by the high cost of electrode and low power density. In this study, the electrochemical structure and power output performance of three novel straw-derived biochar are discussed and characterized by scanning electron microscope, specific surface area, cyclic voltammetry, Raman spectrum, electrochemical impedance spectroscopy etc. Compared with the common carbon felt electrode, the optimal electricity generation ability and electrochemical affinity are obtained in corn straw biochar electrode: the rough surface with macroporous structure and high degree of graphitization facilitates the attachment of electroactive bacteria; the maximum output voltage, open circuit voltage, power density and coulombic efficiency reach 662.64±4.03 mV, 798.24±3.65 mV, 1.54±0.18 W m−2 and 50.39±1.68 %, respectively; the maximum COD removal efficiency of 77.45±1.69 % is achieved; exchange current density (4.6142×10−4 A cm−2) in corn straw electrode presents the better electrochemical activity than that of carbon felt electrode. These implies that corn straw-derived biochar is a competitive raw material for MFC anode.

Thermoeconomic evaluation of waste heat recovery system in aluminium smelters using a parallel two-stage organic Rankine cycle

The primary aluminium industry stands as one of the most energy-consuming and, at times, the most inefficient, with approximately 50 % of energy being lost in the form of waste heat. The multiplicity of wasted heat sources in aluminium smelters presents a challenge in how to recover and integrate them, given their variations in both quantity and temperature levels. In this context, the study adopts the Parallel Two-stage Organic Rankine Cycle (PTORC) to separately integrate the wasted heat from the cathode sidewalls and the exhaust gases within a unified recovery system. The influence of primary and secondary evaporation temperatures, their pinch points, the number of integrated aluminium pots, and the working fluid on the thermodynamic performance and economic feasibility of PTORC are examined. At a given design condition, the findings indicate that decreasing the primary evaporation temperature while increasing the secondary evaporation temperature achieves the optimal operating condition of the system, resulting in a significant improvement in both output power and economic performance, while also reducing exergy destruction. At the primary evaporation temperature of 111.5 °C and the secondary evaporation temperature of 78.5 °C, the net output power reaches the optimal value of 3,840 kW. Furthermore, maintaining a lower pinch temperature difference in both evaporators proves advantageous for enhancing PTORC performance. Pentane, R236ea, and isopentane demonstrate outstanding maximum net power output at a constant secondary evaporation temperature, respectively. Meanwhile, R236ea and isobutane emerge as the most suitable working fluids for PTORC from an economic standpoint.

Experimental Study on Aerodynamic Characteristics of Downwind Bionic Tower Wind Turbine.

The vibrissae of harbor seals exhibit a distinct three-dimensional structure compared to circular cylinders, resulting in a wave-shaped configuration that effectively reduces drag and suppresses vortex shedding in the wake. However, this unique cylinder design has not yet been applied to wind power technologies. Therefore, this study applies this concept to the design of downwind wind turbines and employs wind tunnel testing to compare the wake flow characteristics of a single-cylinder model while also investigating the output power and wake performance of the model wind turbine. Herein, we demonstrate that in the single-cylinder test, the bionic case shows reduced turbulence intensity in its wake compared to that observed with the circular cylinder case. The difference in the energy distribution in the frequency domain behind the cylinder was mainly manifested in the near-wake region. Moreover, our findings indicate that differences in power coefficient are predominantly noticeable with high tip speed ratios. Furthermore, as output power increases, this bionic cylindrical structure induces greater velocity deficit and higher turbulence intensity behind the rotor. These results provide valuable insights for optimizing aerodynamic designs of wind turbines towards achieving enhanced efficiency for converting wind energy.

Biseasonal Changes in Aerobic Capacity and Sports Performance in Highly Trained Mountain Bike Cyclists Applying Elements of the Polarized Training Programme

Abstract Introduction. This study assessed maximal oxygen uptake (VO2max), power output and sports performance in mountain bike cyclists applying elements of the polarized training programme (POL) Material and Methods. Seven cyclists participated in the study. Immediately before the 2-year experiment (T1), and five times during the experiment (T2, T3, T4, T5, T6), incremental and verification tests were performed to assess VO2max, peak aerobic power (Ppeak) and power at the second ventilatory threshold (PVT2). During the experiment, sports performance in mountain bike cyclists at National Championships, European Championships, World Championships, and World Cup were analyzed. The cyclists performed POL for seven months in each year of the experiment. POL included sprint interval training, high-intensity interval training, and low-intensity endurance training. Results. In the group of cyclists VO2max [l∙min−1] increased in T6 (4.14 ± 1.13) compared to T1 (3.74 ± 0.95), Ppeak [W] increased in T4, T5 and T6 (353 ± 78.45; 350.14 ± 87.96; 360.23 ± 93.83; respectively) compared to T1 (324.14 ± 90.24), and PVT2 [W] increased in T3, T4, T5 and T6 (265.57 ± 80.66; 267.29 ± 63.74; 266.43 ± 69.29; 276.71 ± 78.99; respectively) compared to T1 (229.29 ± 62.91). Cyclists’ sports performance improved during the experiment, and one of them won bronze medal at the World Championships. Conclusions. During the biseasonal experiment using elements of the polarized training programme, improvements in VO2max, Ppeak and PVT2 were observed in cyclists, which was accompanied by better sports performance in cycling races.

Coach Education: The Relationship between Lower Extremity Flexibility and Vertical Jump Performance in Soccer

The aim of this study was to investigate the relationship between lower extremity flexibility values and vertical jump performance of elite soccer players. Twenty-six young elite male soccer players voluntarily participated in the study. Age, height, and weight of the participants were determined as descriptive statistics. Lower extremity flexibility (.=ROM) test and vertical jump (counter movement jump=CMJ) performance determination test were applied to the participants. A goniometer was used for lower extremity flexibility measurement and My Jump 2 application, which has proven its validity and reliability, was used for CMJ performances. Descriptive characteristics of the participants included in the study were mean age: 16.23 ±.51 years, height: 172.96 ±7.56 cm, body weight: 63,15±7,69 kg. The mean values of CMJ performance of the participants were: 37,54±5,51; the mean value of lower extremity flexibility angles (ROM) was 115±4,99°. According to the data obtained, a statistically significant relationship was observed between ROM and CMJ performance characteristics of elite soccer players (p=.008) (p<0.05). According to the results obtained, a significant relationship was found between ROM and CMJ performances of soccer players. It can be said that teaching the importance of flexibility exercises to soccer players in soccer training programs and including them in training programs will positively affect the sudden power output performances of soccer players such as jumping.

Power Extraction Performance by a Hybrid Non-Sinusoidal Pitching Motion of an Oscillating Energy Harvester

This study proposes a hybrid pitching motion for oscillating flat plates aimed at augmenting the energy extraction efficiency of an energy harvester. The proposed hybrid pitching motion, within the first half cycle, integrates a non-sinusoidal movement starting at t/T = 0 and progressing to t/T = 0.25, with a sinusoidal movement initiating after t/T > 0.25 and continuing to t/T = 0.5. The second half of the cycle is symmetric to the first half but in the opposite direction. The calculated results show that the proposed hybrid pitching motion outperforms both the sinusoidal and the non-sinusoidal motions. The hybrid pitching motion merges the merits of both the sinusoidal and non-sinusoidal motions to optimize pitch angle variation. This integration is pivotal for enhancing the overall power output performance of an oscillating energy harvester characterized by momentum change that enhances the orientation of the heaving movement, smoother motion transitions, and consistent energy harvesting. The power generation is obtained at wing pitch angles of 55°, 65°, 70°, 75°, and 80° during a hybrid pitching motion. The proposed hybrid pitching motion, set at a pitch angle of 70°, achieves a maximum power output that exceeds the oscillating flat plate using a sinusoidal pitching motion by 16.0% at the same angle.

Intermittent sequential pneumatic compression reduces post-exercise hemodilution and enhances perceptual recovery without improving subsequent cycling performance

Abstract Purpose The present study aims to evaluate the effects of intermittent sequential pneumatic compression (ISPC) in the short-term recovery of a repeated sprint interval exercise, including the assessment of power output performance, hematocrit, legs water, and perceptual recovery. Methods A randomized, counterbalanced, crossover design was conducted. Sixteen healthy trained individuals (F=7, M=9; 27.7 ± 9.4 years; BMI 22.3 ± 2.9) performed two trials of a cycling fatiguing exercise, followed by a recovery phase (ISPC or Sham), and a subsequent performance assessment exercise to evaluate the effects of ISPC in post-exercise recovery. Results There were no significant differences in cycling performance comparing both recovery modes. However, the decrease in the hematocrit levels after the recovery phase was less exacerbated in the ISPC condition compared to Sham (44.03 ± 1.33 vs. 42.38 ± 1.33 %; p = 0.047; d = 0.310). Likewise, the total quality recovery (TQR) was higher after the recovery in the ISPC condition (15.94 ± 0.16 vs. 14.75 ± 0.12 points; p = 0.045; d = 2.125), although no differences were shown previously in power output performance (371.8 ± 22.2 [46.5] vs. 372.4 ± 21.8 [47.2] W; p = 0.986) and rating of perceived exertion (RPE) (17.69 ± 0.41 vs. 17.56 ± 0.31; p = 0.700). Conclusions Contrary to our hypothesis, the application of intermittent sequential pneumatic compression after high-intensity exercise reduces the post-exercise hemodilution response and increases perceptual recovery. However, power output was similar between conditions, challenging the effectiveness of this recovery method in a short-term intervention.