Gravity Variations Research Articles

A superconducting gravimeter on the island of Heligoland for the high-accuracy determination of regional ocean tide loading signals of the North Sea

SUMMARY The superconducting gravimeter GWR iGrav 047 has been installed on the small offshore island of Heligoland in the North Sea approximately at sea level with the overall aim of high-accuracy determination of regional tidal and non-tidal ocean loading signals. For validation, a second gravimeter (gPhoneX 152) has been setup within a gravity gradiometer approach to observe temporal gravity variations in parallel on the upper land of Heligoland. This study covers the determination of regional ocean tide loading (OTL) parameters based on the two continuous gravimetric time-series after elimination of the height-dependent gravity component by empirical transfer functions between the local sea level from a nearby tide gauge and local attraction effects. After reduction of all gravity recordings to sea level, both gravimeters provide very similar height-independent OTL parameters for the eight major diurnal and semidiurnal waves with estimated amplitudes between 0.3 nm s−2 (Q1) and 11 nm s−2 (M2) and RMSE of 0.1–0.2 nm s−2 for 2 yr of iGrav 047 observations and a factor of 2 worse for 1.5 yr of gPhoneX 152 observations. The mean absolute OTL amplitude differences are 0.3 nm s−2 between iGrav 047 and gPhoneX 152, 0.4 nm s−2 between iGrav 047 and the ocean tide model FES2014b and 0.7 nm s−2 between gPhoneX 152 and FES2014b which is in good agreement with the uncertainty estimations. As by-product of this study, OTL vertical displacements are estimated from the height-independent OTL gravity results from iGrav 047 applying proportionality factors ${\rm d}h/{\rm d}g$ for the eight major waves. These height-to-gravity ratios and the corresponding phase shifts are derived from FES2014b. The OTL vertical displacements from iGrav 047 are estimated with amplitudes between 0.4 mm (Q1) and 5.1 mm (M2) and RMSE of 0.1–0.7 mm. These OTL amplitudes agree with FES2014b within 0.0 (M2) and 0.8 mm (K1) with a mean difference of 0.3 mm only. The OTL amplitudes from almost 5 yr of GNSS observations show deviations of up to 6 mm (M2) compared to vertical displacements from both iGrav 047 and FES2014b, which suggests systematic effects included in the estimation of OTL vertical displacements from GNSS. With the demonstrated accuracy, height-independent sensitivity in terms of gravity and vertical displacements along with the high temporal resolution and the even better performance with length of time-series, iGrav 047 delivers the best observational signal for OTL which is representative for a large part of the North Sea.

Thermal instability analysis in magneto-hybrid nanofluid layer between rough surfaces with variable gravity and space-dependent heat source

The onset of thermal instability with hybrid nanoparticles Al2O3–Cu in nanofluid is investigated with the combined effects of variable gravity, variable heat source and Lorentz force in a porous medium. Its applications are in many areas like chemical engineering, geophysics, astrophysics, etc. Based on literature, many gravity variations are assumed in the present analysis, along with a space-dependent heat source/sink parameter that varies along the width of the channel. The finite difference-based Lobatto IIIa method has been applied to solve the system under no nanoparticle flux and rough boundary conditions, and approximate analytical results are generated for some special cases. The roughness parameters ([Formula: see text]), Darcy number (Da), gravity variation function ([Formula: see text]), and Chandrasekhar number (Q) delay the onset of convection and thus stabilize the system. It is also observed that an increase in the Lewis number Le, power index in variable heat source, and the nanoparticle Rayleigh concentration number Rn decreases the critical Rayleigh number [Formula: see text] which destabilizes the system, and increases the critical wave number, which enlarges the convection cell size. In the case of exponential variation ([Formula: see text]) in the gravity variation parameter, the system becomes stabilized due to a delay in the onset of convection. In addition, we have considered multilayer perceptron-artificial neural network (MLP-ANN) computation to predict the critical Rayleigh number as per function of important controlling parameters. The data set of 625 observations is chosen keeping 70% for testing, 15% for training and 15% for validation using efficient Levenberg−Marquardt back propagation algorithm with optimal accuracy measures i.e., root mean square deviation (RMSE), root mean relative error (RMRE) and [Formula: see text] (coefficient of determination). Finally, the regression plots are drawn that correlate, target and output data.

Inferences on the 2021 Ongoing Volcanic Unrest at Vulcano Island (Italy) through a Comprehensive Multidisciplinary Surveillance Network

In September 2021, the La Fossa crater at Vulcano, in Italy, entered a new phase of unrest. We discuss a set of monitoring parameters included in the INGV surveillance network, which closely tracked the sequence of effects related to the crisis. The low-frequency local seismicity sharply increased, while the GPS and tiltmeter networks recorded the inflation of the cone, as an effect of fluid expansion in the hydrothermal system. Gravity variations were probably the effects of fast processes within shallow sources. The anomalies in soil CO2 flux, fumarole temperature, and in plume SO2 flux marked the strong increase in the vapor output from crater fumaroles. The signs of the impending crisis had been evident in the chemical and isotopic composition of fumarole gases since July 2021. These geochemical anomalies were clearly indicative of the enhanced input of gases from a magmatic source. In October, the massive degassing also influenced the areas at the base of the cone. In some areas, soil CO2 degassing and the thermal aquifer recorded strong anomalies. By early November, the crisis reached its acme. Afterward, the monitored parameters started a slow and discontinuous decreasing trend although remaining, some of them, sensibly above the background for several months. The multidisciplinary approach proved decisive for the interpretation of the underlying processes acting in the different phases of the unrest, thus allowing a consistent evaluation of the multiple hazards.

Nonlinear instability analysis of internally heated convection in a porous layer with the impact of magnetic field and variable gravity

AbstractThe impact of the magnetic field, heat source, and variable gravity field on the stability of convective phenomena in a porous layer are investigated numerically. Three types of gravity variations, such as linear, parabolic, and cubic functions are considered. For linear and nonlinear theories, the method of normal modes has been employed to solve governing dimensionless equations. It is found that the onset of convection is delayed by increasing the Hartmann number and gravity variation parameter and enhancement of the internal heat source makes the system stable. The subcritical instability region increases as the Hartmann number and gravity variation parameter increase.

Improved model reference‐based adaptive nonlinear dynamic inversion for fault‐tolerant flight control

AbstractDue to lack of robustness, Nonlinear Dynamic Inversion (NDI) control cannot resist the influence of disturbances. In this paper, an adaptive fault‐tolerant control method, called Improved Model Reference‐based Adaptive NDI (IMR‐ANDI), is proposed and applied to develop a fault‐tolerant flight controller to improve robustness to faults and disturbances. To improve the estimation accuracy, this paper also modified the piecewise‐constant adaptation, which improves the accuracy of adaptive estimation without increasing the sampling frequency. Moreover, a low‐pass filter is introduced to the control law creatively to weaken the disturbance of high‐frequency dynamics to the adaptation, which balances the dynamic performance and robustness as well as prevents the system oscillation. Finally, a fault‐tolerant flight controller is developed based on the IMR‐ANDI and verified under the actuator fault and center of gravity variations. All simulation and hardware‐in‐the‐loop experiment results conform to the theoretical analysis, indicating that the developed IMR‐ANDI fault‐tolerant controller is robust to faults and disturbances and can achieve expected control performance.

An application of mixed-effects model to evaluate the role of age and size on radial variation in wood specific gravity in teak (Tectona grandis)

To test whether radial variation of wood specific gravity (WSG) is controlled by tree age or tree size in teak (Tectona grandis L.f) plantation trees, opposing different-length pith-to-bark strips which represents the differential lateral growth rate was compared using mixed-effects model which considers the heterogeneity of variances and dependency in the data to gain insight into the stochastic processes that govern the wood formation process. Various models were tested in devising an appropriate radial WSG model. Models that accounted for serial correlation in WSG data performed better than the simple structure that assumes zero correlation between measurements. The autoregressive plus random tree effect structure performed better in describing the radial variation pattern. The variability of the data related to random fluctuations during tree development and the wood formation process is modeled by the autoregressive parameter revealing the intrinsic complexity of wood formation. Since they cannot be attributed to observed factors, models should consider temporal or serial correlations when assessing wood quality. The results revealed that tree age is a decisive factor in controlling the WSG of wood, while tree size is statistically less important. Furthermore, the core wood production period varies with the growth rate. It is shown that the core wood area decreased with slow growth. Findings presented here appear to provide the first demonstration of radial variation in WSG with respect to growth rate and age for planted teak growing in Ghana.

Space-time analysis of the longitudinal variation in wood specific gravity of teak and its effect on tree growth and development

The space-time structure of a teak wood specific gravity (SG) dataset was analyzed using a mixed-effects model. Spatial correlation increased in space, a phenomenon attributable to the maturation of apical meristems, while the temporal correlation of vascular meristems decreased over time. The decay of temporal correlation over time was attributed to the diminishing crown effect on the later formed wood further away from the pith, morphogen gradient, and probably changing microenvironmental conditions. The Kronecker product was used to collect spatiotemporal data on the intricate dynamic process of the evolution of the apical and lateral meristems. The results showed that height and relative radial distance (RRD) (i.e., the flow of time with wood formation) were statistically significant factors, with their interaction showing no significance. The results confirm the usefulness of using the space-time approach to elucidate the interaction between the apical and lateral meristems, two major inherent biological systems that control tree growth and wood formation dynamics. To understand the origins of patterns that vary both temporally and spatially in the tree, future work should describe the variation of SG within the tree due to increasing height (space) and diameter (age) as a matrix; then the correlation function can be modelled.

Correlations of HTSD to TBP and Bulk Properties to Saturate Content of a Wide Variety of Crude Oils

Forty-eight crude oils with variations in specific gravity (0.782 ≤ SG ≤ 1.002), sulphur content (0.03 ≤ S ≤ 5.6 wt.%), saturate content (23.5 ≤ Sat. ≤ 92.9 wt.%), asphaltene content (0.1 ≤ As ≤ 22.2 wt.%), and vacuum residue content (1.4 ≤ VR ≤ 60.7 wt.%) were characterized with HTSD, TBP, and SARA analyses. A modified SARA analysis of petroleum that allows for the attainment of a mass balance ≥97 wt.% for light crude oils was proposed, a procedure for the simulation of petroleum TBP curves from HTSD data using nonlinear regression and Riazi’s distribution model was developed, and a new correlation to predict petroleum saturate content from specific gravity and pour point with an average absolute deviation of 2.5 wt.%, maximum absolute deviation of 6.6 wt.%, and bias of 0.01 wt.% was developed. Intercriteria analysis was employed to evaluate the presence of statistically meaningful relations between the different petroleum properties and to evaluate the extent of similarity between the studied petroleum crudes. It was found that the extent of similarity between the crude oils based on HTSD analysis data could be discerned from data on the Kw characterization factor of narrow crude oil fractions. The results from this study showed that contrary to the generally accepted concept of the constant Kw characterization factor, the Kw factors of narrow fractions differ from that of crude oil. Moreover, the distributions of Kw factors of the different crudes were different.

Gravity variations determined from GRACE and GRACE-FO monthly solutions for analyzing water mass changes in the Aral Sea

The GRACE large-scale sequent GRACE-FO gravity satellite mission is providing monthly gravity field solutions for almost 20 years enabling a unique opportunity to monitor large-scale mass variation processes. The gravity anomaly time series for the Aral Sea region has been derived for the period of April 2002 to January 2022. The method of determining gravity anomaly time series from GRACE and GRACE-FO monthly solutions has been improved by taking into account the mass variations of the Caspian Sea. The gravity anomaly time series then has been compared to mass anomaly estimates. For deriving mass anomaly, beyond the available water volume data, density variations were determined by taking into account salinity and temperature changes. Unfortunately, no reliable information either on the salinity or on water temperature changes is available or accessible. Furthermore, not only the data but also the methodology of determining the density is not reliable. Still, the tests suggest that slight improvement in correlation due to the involvement of salinity information occurs.

Assessment of terrigenous and marine sourced oils mixtures: Los Manueles field, Maracaibo basin Venezuela

Seven crude oil samples from Los Manueles field, Maracaibo Basin, Venezuela, were analyzed to evaluate oil mixtures associated with different oil charges into the reservoirs. Analyses of the bulk physicochemical parameters suggest variations in the API gravity, the concentration of saturated and aromatic hydrocarbons, NSO compounds + asphaltenes, sulfur, vanadium, nickel, and the biomarkers distribution. The oils were divided in two groups: G-I with high saturated hydrocarbons and low NSO compounds + asphaltenes, sulfur, vanadium and nickel, a bimodal distribution of n-alkanes, high Pr/Ph and oleanane index, low steranes index, low abundance of tricyclic terpanes and C35S/C34S < 0.54 and G-II with low saturated hydrocarbons and high NSO compounds+ asphaltenes, sulfur, vanadium and nickel, an unimodal distribution of n-alkanes with low Pr/Ph and oleanane index, high steranes index, abundance of tricyclic terpanes and C35S/C34S > 0.70. G-I has a higher contribution of terrigenous organic matter compared to G-II, characterized by a higher contribution of marine organic matter. Source rock lithology biomarker indicators suggest marine shale as the source rock for oils of terrigenous origin. The results indicate that oils were generated by two independent source rocks, La Luna Formation and a secondary source rock with terrigenous organic matter, probably represented by the Capacho Formation.

The study of internal heat and variable gravity field on the onset of convection in a sparsely packed porous medium

The qualitative influence of internal heat and variable gravity field on the onset of convection in a sparsely packed porous layer with horizontal fluid-saturated are investigated. Linear stability analysis is performed using the normal mode technique. The dimensionless governing equations with four cases of gravity field variation: (1) [Formula: see text], (2) [Formula: see text], (3) [Formula: see text], and (4) [Formula: see text] are solved using bvp4c in MATLAB R2020a and the corresponding eigenvalue problem is calculated for three types of boundaries, namely free-free, rigid-free, and rigid-rigid, respectively. The effect of an internal heat parameter [Formula: see text], Darcy number [Formula: see text], and gravity variation parameter [Formula: see text] for the stability of the system is investigated graphically. The critical value of the Rayleigh number and corresponding wavenumber are calculated for other fixed parameters. It is observed that internal heat parameters enhance the onset of convection, whereas the gravity variation parameter delays the same. It is also observed that the system becomes more stable for the exponential variable gravity function and less stable for the cubic variable gravity function.

A long-term charge/discharge cycle at Mt. Etna volcano revealed through absolute gravity and GPS measurements

We present results of repeated absolute gravity and GPS measurements, carried out at Mt. Etna volcano between 2009 and 2018. Absolute gravity measurements are rarely performed along arrays of stations on active volcanoes and, through our unprecedented dataset, we highlight the possibilities of this method to track underground mass changes over long time-scales. Analysis of the residual absolute gravity data and ground deformation reveals a cycle of gravity increase and uplift during 2009 to 2011, followed by gravity decrease and subsidence during 2011 to 2014. Data inversion points to a common mass and pressure source, lying beneath the summit area of the volcano, at depth of ~ 5 km b.s.l. The bulk volume change inferred by the inversion of the deformation data can account for only a small portion of the mass change needed to explain the correspondent gravity variations. We propose that the observed relationship between gravity and vertical deformation was mostly due to the compressibility of the magma in the inferred reservoir, which, in turn, was enhanced by the presence of exsolved gas. Overall, the gravity and deformation data we present reveal a cycle of magma recharge (2009–2011) and discharge (2011–2014) to/from the inferred storage zone. During the recharge phase only degassing occurred from the summit craters of Mt. Etna. During the following phase of discharge, the magma lost from the reservoir at ~ 5 km b.s.l. fed the exceptional phase of volcanic activity during 2011–2014, when tens of lava fountaining episodes took place.

Delineating a volcanic aquifer using groundwater-induced gravity changes in the Tatun Volcano Group, Taiwan

The Tatun Volcanic Group (TVG) is an active volcanic system that poses potential volcanic hazards to northern Taiwan. Groundwater migration can be sensitive to volcanic activities and can induce temporal gravity changes. Here we conducted four gravity measurement campaigns in 2012 with two CG5 relative gravimeters at a total of 31 gravity monitoring sites to probe the spatiotemporal groundwater variability in the TVG area. With careful adjustments to the gravity measurements, the standard point gravity error was approximately 8 μGal on average. The observed gravity changes were compared with the groundwater-induced gravity variations derived from two hydrological models: the continuous flow model that consisted of one permeable layer (Model A) and a dynamic groundwater flow model that used the hydrological solver MODFLOW (Model B). The results show that only gravity observations in the central TVG match the simulated gravity pattern, i.e., the hydrology in the central TVG follows free groundwater flows within the interconnected and porous strata. On the other hand, inconsistencies between simulated and observed gravity changes range from + 40 to – 80 μGal. The discrepancies were located at the eastern and western areas in the TVG and showed opposite variations over time. This pattern of temporal variability cannot be attributed to the use of shallow aquifer models that merely reflect the surface recharges and discharges. We infer that the pattern stems from deep flows, such as hydrothermal fluids alternately replenishing aquifers to the east and west of the TVG, i.e., deep fluid conduits may have developed to the east and west of the TVG and bypassed the central area.

ESMGFZ Products for Earth Rotation Prediction

Abstract The Earth System Modelling Group of GeoForschungsZentrum Potsdam (ESMGFZ) provides geodetic products for gravity variations, Earth rotation excitations, and Earth surface deformations related to mass redistributions and mass loads in the atmosphere, ocean, and terrestrial water storage. Earth rotation excitation compiled as effective angular momentum (EAM) functions for each Earth subsystem (atmosphere, ocean, continental hydrology) are important for Earth rotation prediction. Especially the 6-day forecasts extending the model analysis runs offer essential information for the improvement of ultra-short-term Earth rotation predictions. In addition to the individual effective angular momentum function of each subsystem, ESMGFZ calculates a combined EAM prediction product. Adjusted to the official Earth orientation parameter (EOP) products IERS 14C04 and Bulletin A, this EAM prediction product allows to extrapolate the polar motion and Length-of-Day parameter time series for 90 days into the future via the Liouville equation. ESMGFZ submits such an EOP prediction to the 2nd EOPPCC campaign.

Geophysical evidence for a serpentine mud volcano in the relict slow-spreading center of the South China Sea

The seamounts formed in spreading centers are of basaltic with prominent gravity peaks and high density. But Longmen Seamount, 1.5 km high and ∼ 20 km wide, located in the relict slow-spreading center of the South China Sea, shows a weak gravity peak with a low-amplitude gravity variation (∼19 mGal). To reveal the geological origin of the unusual seamount, we conducted pre-stack depth-migrated image and 3D forward gravity modeling for Longmen Seamount based on the constraint from reflection and refraction seismic data. Our results show that bulk density and seismic velocity of Longmen Seamount is as low as ∼2.1 g/cm3, and 1.6–3.2 km/s, respectively, equivalent to that of poorly consolidated sediments. Furthermore, typical structural elements of the mud volcano system, such as a reflection blank zone, up-bent and downward bending reflections, are observed beneath LM Seamount. For the crust beneath LM Seamount is thin (1.6 km) and highly faulted revealed by numerous clear discontinuous reflections, it is easy for seawater to infiltrate through the thin crust and leads to a high degree of serpentinization of the upper mantle rocks. Combined with serpentine mud volcanoes featuring low bulk density and low seismic velocity, Longmen Seamount is most probably a serpentine mud volcano in a slow-spreading mid-ocean center. For the discovered serpentine mud volcanoes are all restricted to the convergent plate margins, this study will lead to a new understanding of the mechanism of serpentine mud volcanism.

Deformation and necking of liquid droplets in a magnetic field

Pendant droplets of water and paramagnetic solutions are studied in the presence of uniform and nonuniform magnetic fields produced by small permanent magnet arrays, both in static conditions and during dynamic pinch-off. Static measurements of the droplet shape are analyzed in terms of an apparent surface tension γapp or an effective density ρeff. The change of surface tension of deionized water in a uniform field of 450 mT is insignificant, 0.19 ± 0.21 mNm−1. Measurements on droplets of compensated zero-susceptibility solutions of Cu2+, Mn2+, and Dy3+, where the shape is unaffected by any magnetic body force, show changes of surface tension of about −1% in 500 mT. Magnetic field gradients of up to 100 T2 m−1 deform the droplets and lead to changes of ρeff that are negative for diamagnetic solutions (buoyancy effect) and positive for paramagnetic solutions. The droplet profile of strongly paramagnetic 0.1 molar DyCl3 solution is analyzed, treating the nonuniform vertical field gradient as a spatial variation of gravity. The influence of Maxwell stress on the droplet shape is discussed. In dynamic measurements, the droplet shape at pinch-off is recorded by high-speed photography and analyzed in terms of a relative change of dynamic surface tension in the presence of a magnetic field. The surface-tension-dependent prefactor of the scaling law that governs the pinch-off dynamics shows no difference for pure water or 0.11 M DyCl3 solutions in the field. The nonuniform field has no influence in the pinch-off region because the filament diameter is much less than the capillary length.

The Gravity Signal of Mercury's Inner Core

AbstractIn a reference frame rotating with Mercury's mantle and crust, the inner core and fluid core precess in a retrograde sense with a period of 58.646 days. The precession of a triaxial inner core with a different density than the fluid core induces a periodic gravity variation of degree 2, order 1. Elastic deformations from the pressure that the precessing fluid core exerts on the core‐mantle boundary also contribute to this gravity signal. We show that the periodic change in Stokes coefficients ΔC21 and ΔS21 for this signal of internal origin is of the order of 10−10, similar in magnitude to the signal from solar tides. The relative contribution from the inner core increases with inner core radius and with the amplitude of its tilt angle with respect to the mantle. The latter depends on the strength of electromagnetic coupling at the inner core boundary which in turn depends on the radial magnetic field Br; a larger Br generates a larger tilt. The inner core signal features a contrast between ΔC21 and ΔS21 due to its triaxial shape, discernible for an inner core radius >500 km if Br > 0.1 mT, or for an inner core radius >1100 km if Br < 0.01 mT. A detection of this contrast would confirm the presence of an inner core and place constraints on its size and the strength of the internal magnetic field. These would provide key constraints for the thermal evolution of Mercury and for its dynamo mechanism.

Design of adaptive flight control law for center of gravity and mass variation and HIL real-time simulation verification

Considering the influence of the center of gravity (CG) and mass variations on flight dynamics, a nonlinear L1 adaptive control approach is presented in this paper and applied to design a flight controller to achieve the aim of improving the robustness of the flight system against sudden changes in the CG. Based on L1 adaptive control, this approach introduces a feedback linearization strategy to eliminate the known nonlinear dynamics of the aircraft and realize the rapid decoupling of the aircraft states. The nonlinear L1 adaptive control also addresses the problem of insufficient robustness in conventional L1 adaptive control due to overcoming its own known nonlinearities, and then improves the robustness to external disturbances. Additionally, the modified piecewise constant is employed to design the adaptive law to improve the estimation accuracy. Finally, the control performance and robustness of the designed flight control law are verified in the hardware in the loop (HIL) flight control semi-physical experimental platform. Experimental results indicate that the nonlinear L1 adaptive flight control law has strong robustness, which can effectively overcome the disturbance of the CG and mass sudden variations. Moreover, the designed controller takes into account the transient performance while ensuring the steady-state performance of the aircraft with CG change.

Geodynamic hazards and risk assessment at the Karachaganak oil, gas, and condensate field

The geodynamic hazards and risk assessment at the Karachaganak oil, gas, and condensate field (KOGCF) were explored on the northern board of the Pre-Caspian Basin to predict the consequences of the long-term exploitation of this field. We integrate multiple measurements, including repeated accurate leveling, Global Positioning System (GPS) measurements, and high precision gravimetric and seismological monitoring at the KOGCF. The results of geodynamic monitoring at the KOGCF for the first time made it possible to prove noticeable seismic deformation processes in the sedimentary cover under the influence of hydrocarbon production. The vertical displacements and horizontal movement along faults, changes in local gravity anomalies, and earthquake sources at depths comparable to hydrocarbon production intervals at the KOGCF have been identified. The maximum amplitudes of modern vertical movement of the earth's surface and the minimum values of the differently oriented horizontal movement were revealed within the projection on the ground surface of the crest of the carbonate massif (Upper Devonian-Lower Permian age). The results suggest the expansion of uneven compression in the crest of the KOGCF while tension processes occur on its periphery. There is a decrease in gravity variations in relation to the slopes of this massif in areas with active hydrocarbon production. An extended zone of high-gradient steps of ΔGa anomalies, spatially coinciding with the position of fault zones, is mapped along the periphery of the contour of production wells. In the northeastern part of the KOGCF, seismic events were registered practically in the depth intervals of the productive horizons from which hydrocarbons are produced. A spatial relationship between the seismic events and the anomalous deformation activity in the northeast KOGCF has been revealed. Consequently, the field development has provoked both intense deformation of the earth's surface and weak local seismicity.

The effects of technological and traditional feedback on back squat performance in untrained women

BackgroundRecently, a novel method for improving movement quality called open-ended augmented feedback has been introduced. However, the effects of using such feedback in a training intervention have not yet been examined. The aim of this study was to assess the changes in performance and movement quality following a five-week resistance-training program with either (1) technological feedback or (2) traditional, verbal feedback from an experienced trainer.MethodsNineteen untrained females (age: 21.84 ± 2.24 years, height: 169.95 ± 5.92 cm, body mass: 65.05 ± 7.93 kg) randomly allocated to one of the two conditions completed five weeks of training with two weekly sessions. Pre- and post-intervention, participants were tested for physical performance (i.e., back squat and isometric mid-thigh pull strength) and movement quality parameters (weight distribution, center of gravity variation, and subjective rating of the back squat technique).ResultsBoth groups similarly increased the training resistance throughout the intervention (p < 0.01), as well as strength in the back squat (technological feedback group: effect size (ES) = 1.31, p = 0.002; traditional feedback group: ES = 1.48, p = 0.002). Only the traditional feedback group increased isometric mid-thigh pull strength (ES = 1.11, p = 0.008) and subjectively rated lifting technique at the same load (p = 0.046). No changes in force distribution (p = 0.062–0.993) or center of gravity variation (p = 0.160–0.969) occurred in either group when lifting the same absolute loads at post-test. However, both groups displayed a greater variation in center of gravity when lifting the same relative load at post-test (technological feedback group: p < 0.001; traditional feedback group: p = 0.006). No differences were found between the groups for any of the observed changes (p = 0.205–0.401).ConclusionsFive weeks of back-squat training with verbal feedback increased isometric mid-thigh pull strength and subjectively rated lifting technique from pre- to post-test, whereas technological feedback did not. Both methods improved back squat strength and training resistance. For resistance-training beginners, the choice between feedback methods should be based on the desired outcomes and the availability of expertise and equipment.