Stretch Cycles Research Articles

Assessing the Fatigue Stress Behavior of Starch Biodegradable Films with Nanoclay Using Accelerated Survival Test Methods

A destructive degradation model was applied on films made from different concentrations of starch, glycerol and nanoclay using various elongation levels as a stress variable at different stress times and stretch cycles. The log tensile quotient (logarithm of the tensile strength to the corresponding break cycle) was recorded as the response variable. The log tensile quotient increased, and the log exact break time decreased, as the elongation level increased. The treatment containing the highest starch and nanoclay and lowest glycerol content proved to be the most resistant to stress conditions and the most versatile in relation to the varying log tensile quotients, while the treatments containing the lowest nanoclay and highest glycerol contents, regardless of the starch concentration, manifested the lowest log tensile quotient at higher levels of log exact break time. According to multiple regression findings, the break cycle governed mostly the stress conditions in the degradation model, followed by the sample ID and the log exact break time. The term log tensile quotient, attempted for the first time on data concerning biodegradable films enhanced with nanoclay, seems very promising for deeper research due to its ability to retrieve predictive information from survival equations and to discriminate the difference between film structures.

Longevous ionogels with high strength, conductivity, adhesion and thermoplasticity

The longevity of flexible electronics substantially influences their viability for practical use. At present, the service life of pliable devices utilizing conductive gels is frequently compromised due to factors inclusive but not limited to solvent loss. Taking cues from the steadfast structure of human tissues, we hereby delineate a solvent-assisted strategy to fabricate ionogels, predicated on a supramolecular network of hydrogen bonds. Upon subjecting these ionogels to realistic operational environments, it has been empirically ascertained that they maintain a steadfast mechanical and electrical consistency for a minimum duration of 22 months. In terms of dynamic stretchability, they effortlessly endure one million stretch cycles, even when faced with a notch. The induction of a supramolecular structure within the ionogel not only confers exceptional mechanical attributes but also simultaneously enhances conductivity, a feat paralleled by few recent explorations. Furthermore, these ionogels boast of superior anti-freezing and adhesive characteristics, including a toughness extending up to 17.96 MJ/m3 at an ultra-low temperature of −50 °C, and an adhesive capacity permitting movement and bearing of items weighing over 10,000 times its own weight, the lap-shear strength can reach 30.2 kPa. Intriguingly, these gels demonstrate thermoplastic behavior, which facilitates their easy reshaping into diverse forms. Such compelling attributes amplify the potential of supramolecular ionogels, positioning them as formidable contenders for flexible electronics in stringent and challenging scenarios.

Economically viable electromechanical tensile testing equipment for stretchable sensor assessment

The growing interest in soft robotics increases the demand for stretchable sensors. The high performance of stretchable sensors depends much on the linearity, reliability and hysteresis of the stretchable conductive materials. In the applications of conductive materials such as in dielectric elastomer actuators, a stretchable conductive material should maintain the conductivity while sustaining large and multiple cycles of stretch and release tests. To understand the stretchable electrode quality, researchers should perform an electromechanical test. However, researchers require a high investment cost to use a professional type of electromechanical tensile test. In this research, we proposed an economically viable version of the Do-it-yourself (DIY) electromechanical tensile test (EMTT) to resolve the high investment cost problems. The DIY-EMTT is based on the Arduino-nano module. We integrate the load cell, displacement sensor, motor linear stage and DIY resistance meter. We can use the DIY mechanism to suppress the instrumental cost from thousands to hundreds of dollars. Furthermore, we provide a step-by-step guide to build the DIY-EMTT. We expect our DIY-EMTT to boost stretchable sensor development in soft robotics.

Highly elastic polymer substrates with local strain management for stretchable electronic applications

Stretchable electronic devices have been extensively investigated in healthcare and wearable electronics. The stretchable substrate with strain control is paramount to integrating rigid devices into stretchable electronic systems for high mechanical strain. The common approach utilizes rigid strain control islands integrated on the surface of the soft stretchable matrix, but strain concentration effect and poor adhesion at the interface between the rigid islands and the elastic substrate are challenges. In this work, a stretchable substrate is developed by embedding the bottom strain control islands into the interior of an elastic substrate and the top strain control islands on the substrate surface to minimize strain concentration and improve the adhesion of the interface. The simulation results show that the strain concentration at the interface of the top island is suppressed and the maximum strain on the substrate surface is reduced by more than 30%. The interface between strain control islands of PI film and elastic substrate of Ecoflex can maintain more than 3000 stretch cycles under repeated strain of 100%. A stretchable inverter is fabricated based on this stretchable substrate with stretchable conductive wire. It is shown that the voltage transfer characteristics of the stretchable inverter have no significant change under strain of 100% for more than 3000 stretch cycles, demonstrating the capability of this stretchable substrate to integrate rigid devices for reliable stretchable electronic systems.

Mechanical memory based on chromatin and metabolism remodeling promotes proliferation and smooth muscle differentiation in mesenchymal stem cells.

Stem cells respond and remember mechanical cues from the microenvironment, which modulates their therapeutic effects. Chromatin organization and energy metabolism regulate the stem cell fate induced by mechanical cues. However, the mechanism of mechanical memory is still unclear. This study aimed to investigate the effects of mechanical amplitude, frequency, duration, and stretch cycle on mechanical memory in mesenchymal stem cells. It showed that the amplitude was the dominant parameter to the persistence of cell alignment. F-actin, paxillin, and nuclear deformation are more prone to be remolded than cell alignment. Stretching induces transcriptional memory, resulting in greater transcription upon subsequent reloading. Cell metabolism displays mechanical memory with sustained mitochondrial fusion and increased ATP production. The mechanical memory of chromatin condensation is mediated by histone H3 lysine 27 trimethylation, leading to much higher smooth muscle differentiation efficiency. Interestingly, mechanical memory can be transmitted based on direct cell-cell interaction, and stretched cells can remodel the metabolic homeostasis of static cells. Our results provide insight into the underlying mechanism of mechanical memory and its potential benefits for stem cell therapy.

Unveiling Mechanobiology: A Compact Device for Uniaxial Mechanical Stimulation on Nanofiber Substrates and Its Impact on Cellular Behavior and Nanoparticle Distribution.

Biotechnology and its allied sectors, such as tissue culture, regenerative medicine, and personalized medicine, primarily rely upon extensive studies on cellular behavior and their molecular pathways for generating essential knowledge and innovative strategies for human survival. Most such studies are performed on flat, adherent, plastic-based surfaces and use nanofiber and hydrogel-like soft matrices from the past few decades. However, such static culture conditions cannot mimic the immediate cellular microenvironment, where they perceive or generate a myriad of different mechanical forces that substantially affect their downstream molecular pathways. Including such mechanical forces, still limited to specialized laboratories, using a few commercially available or noncommercial technologies are gathering increasing attention worldwide. However, large-scale consideration and adaptation by developing nations have yet to be achieved due to the lack of a cost-effective, reliable, and accessible solution. Moreover, investigations on cellular response upon uniaxial mechanical stretch cycles under more in vivo mimetic conditions are yet to be studied comprehensively. In order to tackle these obstacles, we have prepared a compact, 3D-printed device using a microcontroller, batteries, sensors, and a stepper motor assembly that operates wirelessly and provides cyclic mechanical attrition to any thin substrate. We have fabricated water-stable and stretchable nanofiber substrates with different fiber orientations by using the electrospinning technique to investigate the impact of mechanical stretch cycles on the morphology and orientation of C2C12 myoblast-like cells. Additionally, we have examined the uptake and distribution properties of BSA-epirubicin nanoparticles within cells under mechanical stimulation, which could act as fluorescently active drug-delivery agents for future therapeutic applications. Consequently, our research offers a comprehensive analysis of cellular behavior when cells are subjected to uniaxial stretching on various nanofiber mat architectures. Furthermore, we present a cost-effective alternative solution that addresses the long-standing requirement for a compact, user-friendly, and tunable device, enabling more insightful outcomes in mechanobiology.

Topological MXene Network Enabled Mixed Ion-Electron Conductive Hydrogel Bioelectronics.

Mixed ion-electron conductive (MIEC) bioelectronics has emerged as a state-of-the-art type of bioelectronics for bioelectrical signal monitoring. However, existing MIEC bioelectronics is limited by delamination and transmission defects in bioelectrical signals. Herein, a topological MXene network enhanced MIEC hydrogel bioelectronics that simultaneously exhibits both electrical and mechanical property enhancement while maintaining adhesion and biocompatibility, providing an ideal MIEC bioelectronics for electrophysiological signal monitoring, is introduced. Compared with nontopology hydrogel bioelectronics, the MXene topology increases the dynamic stability of bioelectronics by a factor of 8.4 and the electrical signal by a factor of 10.1 and reduces the energy dissipation by a factor of 20.2. Besides, the topology-enhanced hydrogel bioelectronics exhibits low impedance (<25 Ω) at physiologically relevant frequencies and negligible impedance fluctuation after 5000 stretch cycles. The creation of multichannel bioelectronics with high-fidelity muscle action mapping and gait recognition was made possible by achieving such performance.

Highly stretchable conductor with elastomeric passivation sheath enabling applications in harsh conditions

The rapid development of robotics requires stretchable electrical conductors capable of large deformations and having high operational stability in terms of electrical and mechanical characteristics. Carbon nanotubes (CNT) have been considered as the primary component of stretchable conductors, and mechanically drawn CNT sheets have shown their functionality when combined with various elastomeric materials in the shape of yarns. Herein, an electrically passivated stretchable conductor with an elastomer sheath and a spandex–CNT coiled-yarn core structure is reported. Based on the proven performance of spandex–CNT coiled-yarn, the electrical insulation by the Ecoflex elastomer enhances its applicability in an actual situation without degrading the stretchable conductor functionality. The experimental results show a substantial working deformation range (up to 350%), high durability, and low resistance variation during repetitive stretch and release cycles. Additionally, its stability is confirmed over a wide temperature range (up to 150 °C) and even inside an acidic liquid environment where the elastomeric sheath protects the conducting core. The perfect cooperation between the Ecoflex sheath and spandex–CNT core opens the possibility of deploying this stretchable conductor technology under harsh conditions.

A novel modular opto-biomechatronics bioreactor for simultaneous isotropic mechanical stretch application and fluorescence microscopy under cell and tissue culture conditions

Mechanical stresses are an environmental challenge virtually all tissues in the body are exposed to and thus, are of fundamental interest to study cell reactions in mechanobiology. Yet, unlike acute short-term mechanical cell stimulations, long-term or cyclic mechano-stimulation as experienced in the body is difficult to reproduce. Bioreactors are designed to control cell culture conditions, but still, there are yet no technical solutions available to merge bioreactor and opto-biomechatronics technologies for cyclic stretch-applications and simultaneous live cell imaging. To close this gap, we have engineered an opto-biomechatronics module, consisting of our in-house developed IsoStretcher technology and customised epifluorescence optics, into an automated bioreactor platform. For this, redesigned polydimethylsiloxane (PDMS) chambers with closed geometry (∽700μL internal volume) to warrant sterile operation were developed. Those chambers could be flushed with cell solution for cell seeding in a sterile manner. The epifluorescence imaging module was engineered into the reactor underneath the IsoStretcher to allow for continuous image acquisition during long-term stretch cycles (hours to days). The system was validated on human fibroblast BJ foreskin cells, and Cal-520 Ca2＋ fluorescence was stably imaged using our in-built autofocus functionality. Cultures for 24h within the IsoStretcher-bioreactor preserved a normal cell morphology as compared to external incubator control cultures. Isotropic stretch was reliably transferred to the cell membranes. Our system with in-built bioreactor and opto-biomechatronics functionality provides a holistic technology platform for the growing field of mechanobiology to allow long-term observations of cultured single cells and confluent cell layers that are subjected to cyclic long-term isotropic stretch protocols.

Influence of sarcomeric protein mutations on myocardial function in a 3D-disease model of human iPSC-derived bioartificial cardiac tissue

Abstract Background Peripartum cardiomyopathy (PPCM) is a rare type of cardiomyopathy that occurs in women without prior history of heart disease at later stages of pregnancy or several months after childbirth (1). The disease is characterized by lowered left ventricular ejection fraction (LVEF&amp;lt;45%) and can lead to heart failure if left untreated (1). Approximately 20% of PPCM patients harbor sarcomeric mutations, from which titin truncating variants (TTNtv-s) have the highest pathogenic potential (2). However, the role of such genetic defects of the contractile apparatus on PPCM pathogenesis is not well understood. Purpose The study aims to establish an in vitro 3D disease model of PPCM to elucidate the role of sarcomeric mutations, including titin mutations, in its etiology. We hypothesize, that the disease phenotype can be uncovered in vitro via the stimulation of PPCM patient-derived Bioartificial Cardiac Tissues (BCTs), utilizing pregnancy-related factors in our custom-made bioreactors (3). Methods We selected three patients carrying previously unstudied mutations in the TTN gene for the study. The iPSC reprogramming was performed using a commercial, Sendai virus-based kit. Pluripotency was confirmed via flow cytometry and immunofluorescence stainings. The presence of mutations was confirmed by exome sequencing. Cardiomyocyte differentiation (4) and BCT generation (3) were carried out via established protocols. Following maturation, BCTs were stimulated with the pregnancy-related factors, and tissue forces were measured in the bioreactors. These forces include intrinsically generated (spontaneous) and electrically induced (paced) contraction forces (mN), as well as passive forces, which correlate with tissue stiffness. Results We successfully generated two clonal induced pluripotent stem cell (iPSC) lines from each patient. We confirmed that all of the cell lines were &amp;gt;90% positive for pluripotency markers. After differentiation, CMs contracted spontaneously from day 7 onwards and were &amp;gt;95% positive for cardiac markers (SA, MF20, cTnT). The BCTs remodeled and started contracting on days 1-2 after generation, similarly to wild-type tissues in the baseline conditions. Prolactin treatment of Patient A, harboring a missense mutation in titin, did not show significant functional effects. We confirmed, that patients B and C harbor TTNtvs, and tissues from these patients show a trend of altered stiffness after stimulation with repeated mechanical stretch cycles or β-adrenergic agonist isoprenaline. Further analysis of the underlying mechanisms investigating metabolic changes, signaling pathways, and transcriptomics are ongoing. Conclusion The established iPSC and tissue engineering technologies offer a valuable tool for the development of an iPS-CM-based 3D in vitro disease model for PPCM, which can be used for risk stratification of individual and combined sarcomeric mutations and the development of tailored therapeutic strategies.

Fatigue-resistant hydrogel optical fibers enable peripheral nerve optogenetics during locomotion.

We develop soft and stretchable fatigue-resistant hydrogel optical fibers that enable optogenetic modulation of peripheral nerves in naturally behaving animals during persistent locomotion. The formation of polymeric nanocrystalline domains within the hydrogels yields fibers with low optical losses of 1.07 dB cm-1, Young's modulus of 1.6 MPa, stretchability of 200% and fatigue strength of 1.4 MPa against 30,000 stretch cycles. The hydrogel fibers permitted light delivery to the sciatic nerve, optogenetically activating hindlimb muscles in Thy1::ChR2 mice during 6-week voluntary wheel running assays while experiencing repeated deformation. The fibers additionally enabled optical inhibition of pain hypersensitivity in an inflammatory model in TRPV1::NpHR mice over an 8-week period. Our hydrogel fibers offer a motion-adaptable and robust solution to peripheral nerve optogenetics, facilitating the investigation of somatosensation.

A stretchable slippery surface fabricated by femtosecond laser direct writing

Surface conditions of flexible electronic devices can affect their accuracy, so it is necessary to keep surfaces clean and stable to ensure their correct-long-term operation. The Nepenthes-inspired slippery surface has excellent self-cleaning, stability, and self-healing properties. A slippery surface with stretching durability is significant for application to a flexible sensors surface. As an advanced micro-nanomanufacturing method, femtosecond laser has become an effective method for preparing porous structures to process a slippery surface. In this study, a femtosecond laser was used to prepare an interconnected porous structure on pre-stretched polydimethylsiloxane in one step. The slippery surface was prepared after being infused with lubricant, which maintained the slippery performance under tensile conditions and after hundreds of stretch cycles. Moreover, it exhibits remarkable self-cleaning and chemical stability. This stretchable slippery surface prepared by femtosecond laser direct writing presents good prospects for flexible electronic devices that require a stable surface in various extreme environmental applications.

A Stretchable Solid Ionic Electrode-Based Triboelectric Nanogenerator for Biomechanical Energy Harvesting and Self-Powered Sensors.

Stretchable power devices and self-powered sensors have become increasingly desired for wearable electronics and artificial intelligence. In this study, an all-solid-state triboelectric nanogenerator (TENG) is reported, whose one solid-state structure prevents delamination during stretch and release cycles and increasing the patch adhesive force (3.5N) and strain (586% elongation at break). Through the synergetic virtues of stretchability, ionic conductivity, and excellent adhesion to the tribo-layer, reproducible open-circuit voltage (VOC ) of 84V, charge (QSC ) of 27.5nC, and short-circuit current (ISC ) of 3.1µA after drying at 60°C or 20,000 contact-separation cycles are obtained. Apart from contact-separation, this device shows unprecedented electricity generation through stretch-release of solid materials leading to a linear relationship between VOC and strain. For the first time, this work provides a clear explanation of the working mechanism of contact-free stretching-releasing and investigates the relationships of exerted force, strain, thickness of the device, and electric output. Benefitting from the one solid-state structure, this contact-free device remains stable even after repeated stretch-release cycling, maintaining 100% of its VOC after 2500 stretch-release cycles. These findings provide a strategy toward highly conductive and stretchable electrodes for harvesting mechanical energy and health monitoring.

Fatigue-resistant, single-phase stretchable materials via crack bridging

Stretchable materials such as elastomers and hydrogels are vulnerable to the growth of a crack under repeated cycles of stretch. This is because in single-network/phase materials, the crack can easily propagate by fracturing a single layer of polymer chains. Therefore, to improve the fatigue resistance of stretchable materials, current methods focus on blocking the crack front by another intrinsically high-energy phase. Such high-energy phases, however, are often limited to specific polymers or compromise other properties, limiting its extension to other fields. Single material approaches have been used in structural materials but considered inapplicable to soft materials. Here we challenge this acknowledgement by demonstrating the crack bridging effect in micropatterned elastomers. Instead of resisting in front of crack tips, micropatterns shield polymer chains by bridging behind the crack front. To utilize the bridging effect, we create composites with one material. They are structurally one piece of material but have molecularly separated fibers and matrices due to different curing mechanisms of components. Single-phase composites of polydimethylsiloxane (PDMS) made by this strategy have a fatigue threshold three times higher than that of PDMS-hydrogel composites designed based on the classic high-energy strategy. This crack bridging strategy does not rely on the inter- and intra-polymer interactions provided by specific materials, and thus have a general usefulness.

Gas-permeable and stretchable on-skin electronics based on a gradient porous elastomer and self-assembled silver nanowires

On-skin electronics offers a noninvasive method for continuous and stable signal monitoring, which has played a significant role in healthcare and rehabilitation engineering. However, most present on-skin electronicses are highly restricted by their gas permeability and stretchability due to the materials, fabrication process, and cost. This study develops gas-permeable and stretchable on-skin electronics fabricated via a gradient porous elastomer and self-assembled silver nanowires. The introduction of a gradient porous structure offers the elastomer substrate a good water vapor permeability of 3073.3 g day−1 m−2, which is much higher than the average evaporation rate of water vapor on human skin (432 g day−1m−2). Additionally, the examined electronic device has no adverse effects on the skin and possesses good stretchability and flexibility (110%, 0.07778 MPa). In addition, it offers excellent fatigue resistance (0.70% electrical resistance change within 1000 stretch cycles). The electronic device achieves conformal and comfortable contact with human skin for a long period of wearing and accomplishes high-quality biopotential measurement with a high signal-to-noise ratio (SNR) during electromyography (EMG) signal detection. The proposed simple fabrication process may supply inspiration for new on-skin electronics used in biological signal detection and rehabilitation engineering.

Respiratory Rate as a Factor in Lung Injury-Not Just What You Set, but How You Set.

Respiratory Rate as a Factor in Lung Injury-Not Just What You Set, but How You Set.

Characterization of highly linear stretchable sensor made of Gr-PEDOT:PSS/MnO2 nanowires/Ecoflex composite

This paper proposes a nanocomposite strategy for fabricating ultra-stretchable strain sensors using graphene/poly 3,4-ethylenedioxythiophene:poly styrene sulfonate (Gr-PEDOT:PSS) and manganese oxide nanowires (MnO2 NWs). The sensor response pertaining to different concentrations of MnO2 NWs in the composite was experimentally analysed. Owing to the MnO2 NWs reinforcement, the sensor exhibited a single and highly linear region response over a wide strain range of 0 % to 320 %, with a mean gauge factor of 0.8 when the MnO2 NW concentration was 0.25 % w/v. Moreover, the response time was quite short (79 ms), and an extremely low level of hysteresis behaviour was observed, even in a high strain regime. The sensor showed a highly stable and repeatable response over 5000 stretch and relax cycles. The results demonstrated that the proposed sensor can be applied for human motion detection in scenarios involving large deformation.

Passive force enhancement is not abolished by shortening of single rabbit psoas fibres

Passive force enhancement is defined as the increase in steady-state passive force following deactivation of an actively stretched muscle compared to the corresponding passive force following passive stretching of the muscle. Passive force enhancement has been associated with contributing to the residual force enhancement property, providing stability to sarcomeres, and preventing sarcomeres from over-stretching during eccentric muscle action. Despite its functional importance, the molecular mechanisms underlying passive force enhancement remain unknown. Specifically, it remains unknown how passive force enhancement develops and how it is abolished. Incidental observations on cat soleus muscles led to the speculation that passive force enhancement is abolished when the actively stretched muscle is deactivated and then passively shortened to its pre-stretched length. Here, we tested this hypothesis using skinned fibres from rabbit psoas and rejected it. Rather, we found that passive force enhancement increased following shortening of the fibres to their pre-stretched length (2.4 µm), and furthermore, that the passive force enhancement increased by 70–106% when the shortening and subsequent stretch to the original length (3.6 µm) increased in duration (200 ms, 6 s, and 14 s). These results indicate that passive force enhancement increases during a shortening–stretch cycle, and that this increase is time-dependent. We propose that this increase in passive force enhancement is caused by titin; specifically, with a refolding of titin’s immunoglobulin domains that were unfolded during the active fibre stretching that produced the residual and passive force enhancement. Molecular level experiments are required to test this proposal.

MXene-Enabled Self-Adaptive Hydrogel Interface for Active Electroencephalogram Interactions.

Human-machine interaction plays a significant role in promoting convenience, production efficiency, and usage experience. Because of the universality and characteristics of electroencephalogram (EEG) signals, active EEG interaction is a promising and cutting-edge method for human-machine interaction. The seamless, skin-compliant, and motion-robust human-machine interface (HMI) for active EEG interaction has been in focus. Herein, we report a self-adaptive HMI (PAAS-MXene hydrogel) that can activate rapid gelation (5 s) using MXene cross-linking and conformably self-adapt to the scalp to help improve signal transduction. In addition to exhibiting satisfactory skin compliance, appropriate adhesion, and good biocompatibility, PAAS-MXene has demonstrated electrical performance reliability, such as low impedance (<50 Ω) at physiologically relevant frequencies, stable polarization potential (the rate of change is less than 6.5 × 10-4 V/min), negligible ion conductivity, and impedance change after 1000 stretch cycles, thereby realizing acquisition of EEG signals. In addition, a cap-free EEG signal acquisition method based on PAAS-MXene has been proposed. These findings confirm the high-precision detection ability of PAAS-MXene for electrocardiogram signals and EEG signals. Therefore, PAAS-MXene offers an option to actively control intention, motion, and vision through active EEG signals.

Post-Isometric Back Squat Performance Enhancement of Squat and Countermovement Jump.

The effectiveness of isometric conditioning activity (CA) is not well described in terms of the level of performance enhancement and the presence of a stretch and shortening cycle in subsequent explosive tasks. Therefore, the aim of this study was to evaluate the effect of a maximum isometric squat as the CA and a subsequent squat jump (SJ) and countermovement jump (CMJ) height. A total of 31 semi-professional handball and soccer players were randomly assigned to two different conditions: (i) 3 sets of 3 repetitions (each lasting 3 s) of maximum isometric back squats (EXP), and (ii) no CA (CTRL). The jump height measurements were performed 5 min before the CA and approximately at the 4th and 8th minute following the completion of the CA. Due to the high inter-individual variability in the potentiation responses, the best value obtained post-CA was also analyzed. The SJ height significantly increased from baseline to the 8th minute post-CA (p = 0.004; ES = 0.31; Δ = +3.1 ± 5.0%) in the EXP condition. On the other hand, the CMJ height was significantly higher in the 4th (p = 0.001; ES = 0.23; Δ = +2.7 ± 3.7%) and 8th minute post-CA (p = 0.005; ES = 0.32; Δ = +3.6 ± 5.7%) in comparison to baseline during the EXP condition. Furthermore, SJ height significantly increased from baseline to the best time-point during the EXP (p < 0.001; ES = 0.47; Δ = +4.9 ± 4.9%) and CTRL (p = 0.038; ES = 0.21; Δ = +2.5 ± 5.8%) condition. Moreover, the CMJ height was significantly higher at the best time-points than at the baseline during EXP (p < 0.001; ES = 0.53; Δ = +5.6 ± 4.7%) and CTRL (p = 0.002; ES = 0.38; Δ = +3.1 ± 5.2%) condition. The findings from this study indicate that a maximum isometric squat, used as a CA, effectively improved SJ and CMJ height. This suggests that the presence or absence of a stretch and shortening cycle in both CA and post-CA tasks does not significantly impact the post-activation performance enhancement response.