Incremental Loading Test Research Articles

Muscular Strength Is Associated with Higher Intraocular Pressure in Physically Active Males.

The positive association between intraocular pressure (IOP) and relative maximum force may have relevance for exercise recommendations when IOP is a concern. The relationship between exercise and IOP has been approached in several studies. However, the influence of muscle function on IOP remains underexplored. This study aimed to determine the relationship between the maximal mechanical capabilities of muscles to generate force, velocity, and power with IOP. Sixty-five physically active males participated in this cross-sectional study. Baseline IOP measures were obtained by rebound tonometry, and participants performed an incremental loading test in the ballistic bench press. Baseline IOP showed a strong positive correlation with relative maximum force (r65 = 0.85, P < .001) relative maximum power (r65 = 0.85, P < .001), and relative one-repetition maximum (r65 = 0.91, P < .001). Also, a moderate positive association was obtained between baseline IOP and maximum force (r65 = 0.74, P < .001), maximum power (r65 = 0.72, P < .001), and maximum dynamic strength (r65 = 0.80, P < .001). No significant correlations between IOP and maximal velocity were obtained (all P > .05). There is a positive association between greater upper-body power and strength with higher baseline IOP, which might have important implications in the management of ocular health and especially in individuals constantly involved in resistance training programs (e.g., military personnel, weightlifters). The possible protective effect of high fitness level on the acute IOP response to strength exercise needs to be addressed in future studies.

Fitness Level Modulates Intraocular Pressure Responses to Strength Exercises

ABSTRACTPurpose/Aim: The execution of strength exercises has demonstrated to increase the intraocular pressure (IOP) levels, and it may have a negative impact on the ocular health. We aimed to explore the influence of fitness level on the acute IOP response to strength exercises performed under different loading conditions, as well as to test whether the IOP responses differ between the bench press and jump squat when performed against the same relative loads.Materials and Methods: Forty military personnel males were divided in two subgroups (20 high-fit and 20 low-fit) based on their relative to body mass one-repetition maximum (1-RM). Participants performed an incremental loading test in the bench press and jump squat exercises, and IOP was assessed before and after each repetition by rebound tonometry.Results: IOP increased immediately after executing both exercises (p < 0.01 in both cases), being the magnitude of the IOP increment positively and linearly associated with the increment of the load in both groups (i.e., high-fit and low-fit) and in both exercises (R2 range: 0.81–1.00). Higher fitness level attenuated the IOP rise produced by both exercises (p < 0.01 in both cases). The bench press induced higher IOP increments than the jump squat for both groups at relative loads of ~50%1-RM and ~60%1-RM (p < 0.01 in all cases).Conclusions: These data indicate that IOP increases as a consequence of performing strength exercises, being the increment accentuated with the increase of the load and in the bench press compared to the jump squat exercise. Of special importance would be that the IOP responses were significantly reduced in high-fit individuals. These findings should be addressed in glaucoma patients.

A study on the susceptibility of high strength tempered martensite steels to hydrogen embrittlement (HE) based on incremental step load (ISL) testing methodology

Incremental step load (ISL) technique was used to determine the material susceptibility of three different grades of tempered martensite steels 35CrMo4, 41Cr4 and 36NiCrMo4 to hydrogen embrittlement (HE). In addition to testing the steel grades in air, the environmental hydrogen embrittlement susceptibilities (EHE) of each material were determined by in-situ charging of hydrogen at three different cathodic potentials −0.85 VSCE, −1VSCE and −1.2VSCE to obtain the entire threshold curves for these materials. Overall investigation implies that 35CrMo4 is more susceptible than 41Cr4 and 36NiCrMo4. The fracture surface morphology in case of 35CrMo4 is entirely intergranular at −1VSCE and −1.2VSCE showing the severity of embrittlement. The higher matrix-cementite interfaces along with high cementite and low manganese sulphide (MnS) inclusion content of 36NiCrMo4 influencing the hydrogen transport kinetics within the material are responsible for the lower material susceptibility. The thermal desorption analyses (TDA) further corroborate the observations.

Effects of \u03b2-alanine supplementation during a 5-week strength training program: a randomized, controlled study

Backgroundβ-Alanine (BA) is a non-essential amino acid that has been shown to enhance exercise performance. The purpose of this investigation was to determine if BA supplementation improved the adaptive response to five weeks of a resistance training program.MethodsThirty healthy, strength-trained individuals were randomly assigned to the experimental groups placebo (PLA) or BA. Over 5 weeks of strength training, subjects in BA took 6.4 g/day of BA as 8 × 800 mg doses each at least 1.5 h apart. The training program consisted of 3 sessions per week in which three different leg exercises were conducted as a circuit (back squat, barbell step ups and loaded jumping lunges). The program started with 3 sets of 40 s of work per exercise and rest periods between sets of 120 s in the first week. This training volume was then gradually built up to 5 sets of 20 s work/60 s rest in the fifth week. The work load during the program was set by one of the authors according to the individual’s perceived effort the previous week. The variables measured were average velocity, peak velocity, average power, peak power, and load in kg in a back squat, incremental load, one-repetition maximum (1RM) test. In addition, during the rest period, jump ability (jump height and power) was assessed on a force platform. To compare data, a general linear model with repeated measures two-way analysis of variance was used.ResultsSignificantly greater training improvements were observed in the BA group versus PLA group (p = 0.045) in the variables average power at 1RM (BA: 42.65%, 95% CI, 432.33, 522.52 VS. PLA: 21.07%, 95% CI, 384.77, 482.19) and average power at maximum power output (p = 0.037) (BA: 20.17%, 95% CI, 637.82, 751.90 VS. PLA; 10.74%, 95% CI, 628.31, 751.53). The pre- to post training average power gain produced at 1RM in BA could be explained by a greater maximal strength gain, or load lifted at 1RM (p = 0.014) (24 kg, 95% CI, 19.45, 28.41 VS. 16 kg, 95% CI, 10.58, 20.25) and in the number of sets executed (p = 0.025) in the incremental load test (BA: 2.79 sets, 95% CI, 2.08, 3.49 VS. PLA: 1.58 sets, 95% CI, 0.82, 2.34).Conclusionsβ-Alanine supplementation was effective at increasing power output when lifting loads equivalent to the individual’s maximal strength or when working at maximum power output. The improvement observed at 1RM was explained by a greater load lifted, or strength gain, in response to training in the participants who took this supplement.

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short‐term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic‐plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

Effectiveness of Different Training Programs for Physical Performance Maintenance under the Condition of Low Motor Activity

Investigations made by the World Health Organization have shown that lack of physical activity and sedentary lifestyle are among ten major causes for death and disability. Typically, studies of the negative effects of reduced physical activity and their prevention face difficulties of providing standard conditions. These issues were obviated successfully in the Mars-500 experiment on simulation of a space exploration mission. The sample of subjects consisted of six volunteers from Russia, France, Italy, and China, who were isolated in a limited space for 520 days. To prevent the negative effects of low physical activity, the volunteers performed resistive and cyclic exercises in different periods of isolation. The study was designed with two pauses in the training program. Physical performance was evaluated with an incremental loading test, maximal voluntary effort test (Russian–Austrian MDS resistive exercise system), and PWC-170 (bicycle ergometer). The level of physical performance of the subjects in this experiment never degraded to below baseline values. The proposed training system comprising different kinds of exercise ensured stability or improvement physical performance as compared with the baseline level.

Hydrogen Embrittlement Susceptibility of Bainite for High Strength Steel Fasteners

Industrial fasteners of two different steel microstructures were investigated using incremental step load testing based on ASTM F1624, Standard Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique. The microstructures consisted of tempered martensite and lower bainite. The purpose was to compare hydrogen embrittlement (HE) susceptibility at different hydrogen charging conditions. The results showed that lower bainite exhibited marginally lower HE susceptibility when tested under moderate hydrogen charging conditions (e.g., −1.0 V). At the most severe hydrogen charging potential of −1.2 V, both microstructures are equally embrittled. These results are explained by the differences in the transport and trapping kinetics of hydrogen in bainite as compared to martensite.

IMPROVED SOIL-PILE INTERACTION OF FLOATING PILE IN SAND WITH SHAFT TREATMENT

The present study explored the efficacy of pile shaft surface treatment on the improvement of soil-pile frictional resistance for floating or friction piles. 4 surface conditions of model piles measuring 200 mm long and 20 mm in diameter were examined, namely smooth (control), roughened, fishbone and checked shafts. A pile cap made of plywood was fixed to the top of the pile with 10 mm embedment depth, leaving 190 mm clearance for installation in the sand bed. The test chamber was a see-through glass tank with a footprint of 100 mm x 200 mm and 300 mm height. Coarse sand of D50 = 1.5 mm were loosely placed in the chamber by layers up to 200 mm height before the piles were installed either in single or triple group formations. The incremental load test of conducted via application of dead load ranging between 0.01-0.08 kPa on the pile cap, and the corresponding settlement was recorded. The test results revealed settlement to be reduced by the piles in the order of roughened > fishbone > checked > smooth for the single pile configuration, with maximum reduction of 40 % recorded by the roughened pile. As for the pile group, settlement reduction of the piles with surface treatment clearly outperformed the control pile by almost 50 %, though differences between the former were marginal with seemingly overlapping stress-strain plots. All in all the surface treatment of pile shaft enhanced the shaft friction for the piles installed in sand, but field implementation would require further examination of the pile-driving efficiency as the improved piles could cause additional resistance during installation.

Load–velocity profiling in the military press exercise: Effects of gender and training

This study aimed (1) to analyze the accuracy of mean propulsive velocity to predict the percentage of the 1-repetition maximum in the seated military press exercise and (2) to test the effect of gender and of a resistance training program on the load–velocity profile. The load–velocity relationships of 26 men and 13 women were evaluated by means of an incremental loading test up to the individual 1-repetition maximum. Additionally, the load–velocity relationships of 24 of those 26 men were measured again after a six-week resistance training program. Individual load–velocity relationships had very high coefficients of determination and low standard errors of the estimate (R2 = 0.987; standard error of the estimate = 0.04 m/s). Differences higher than 10% between the individual and the general load–velocity profiles as well as a high between-participants’ variability for the mean propulsive velocity attained at each 1-repetition maximum (coefficient of variation = 12.9–24.6%) were identified. The load–velocity profiles proved to be affected by both the gender (higher mean propulsive velocity at each %1-repetition maximum for men) and the resistance training program (lower mean propulsive velocity at each %1-repetition maximum after training). Taken together, these results speak in favor of creating individual profiles instead of using general equations when using the load–velocity relationship to estimate relative load.

Levels of Hepatic Activating Transcription Factor 6 and Caspase-3 Are Downregulated in Mice after Excessive Training

Recently, we demonstrated that different running overtraining (OT) protocols with the same external load, but performed downhill (OTR/down), uphill (OTR/up), and without inclination (OTR), led to hepatic fat accumulation. As the disruption of endoplasmic reticulum (ER) homeostasis is linked to animal models of fatty liver disease, we investigated the effects of these OT models on the proteins related to ER stress (i.e., BiP, inositol-requiring enzyme 1, protein kinase RNA-like endoplasmic reticulum kinase, eIF2alpha, ATF6beta, and glucose-regulated protein 94) and apoptosis (C/EBP-homologous protein, Caspase-3, 4, and 12, Bax, and tumor necrosis factor receptor-associated factor 2) in livers of C57BL/6 mice. Also, aerobic training can attenuate cardiac ER stress and improve exercise capacity. Therefore, we investigated whether the decrease in performance induced by our OT protocols is linked to ER stress and apoptosis in mouse hearts. The rodents were divided into six groups: naïve (N, sedentary mice), control (CT, sedentary mice submitted to the performance evaluations), trained (TR), OTR/down, OTR/up, and OTR groups. Rotarod, incremental load, exhaustive, and grip force tests were used to evaluate performance. After the grip force test, the livers and cardiac muscles (i.e., left ventricle) were removed and used for immunoblotting. All of the OT protocols led to similar responses in the performance parameters and displayed significantly lower hepatic ATF6beta values compared to the N group. The OTR/down group exhibited lower liver cleaved caspase-3 values compared to the CT group. However, the other proteins related to ER stress and apoptosis were not modulated. Also, the cardiac proteins related to ER stress and apoptosis were not modulated in the experimental groups. In conclusion, the OT protocols decreased the levels of hepatic ATF6beta, and the OTR/down group decreased the levels of hepatic cleaved caspase-3. Also, the decrease in performance induced by our OT models is not associated with ER stress and apoptosis in mice hearts.

Effect of different velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles

ABSTRACTThis study compared the effects of two velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles. Twenty men were counterbalanced in two groups (VL10 and VL20) based on their maximum power capacity. Both groups used the same exercises, relative intensity and repetition volume, only differing in the velocity loss threshold of each set (VL10: 10% vs. VL20: 20%). Pre- and post-training assessments included an incremental loading test and a 15-m linear sprint to assess the force- and load-velocity relationships and athletic performance variables, respectively. No significant between-group differences (P > 0.05) were observed for the force-velocity relationship parameters (ES range = 0.15–0.42), the MPV attained against different external loads (ES range = 0.02–0.18) or the 15-m sprint time (ES = 0.09). A high between-participants variability was reported for the number of repetitions completed in each training set (CV = 30.3% for VL10 and 29.4% for VL20). These results suggest that both velocity loss thresholds induce similar changes on the lower-body function. The high and variable number of repetitions completed may compromise the velocity-based approach for prescribing and monitoring the repetition volume during a power-oriented resistance training program conducted with the countermovement jump exercise.

Feasibility of the 2-Point Method for Determining the 1-Repetition Maximum in the Bench Press Exercise.

This study compared the concurrent validity and reliability of previously proposed generalized group equations for estimating the bench press (BP) 1-repetition maximum (1RM) with the individualized load-velocity relationship modeled with a 2-point method. Thirty men (BP 1RM relative to body mass: 1.08 [0.18] kg·kg-1) performed 2 incremental loading tests in the concentric-only BP exercise and another 2 in the eccentric-concentric BP exercise to assess their actual 1RM and load-velocity relationships. A high velocity (≈1m·s-1) and a low velocity (≈0.5m·s-1) were selected from their load-velocity relationships to estimate the 1RM from generalized group equations and through an individual linear model obtained from the 2 velocities. The directly measured 1RM was highly correlated with all predicted 1RMs (r = .847-.977). The generalized group equations systematically underestimated the actual 1RM when predicted from the concentric-only BP (P < .001; effect size = 0.15-0.94) but overestimated it when predicted from the eccentric-concentric BP (P < .001; effect size = 0.36-0.98). Conversely, a low systematic bias (range: -2.3 to 0.5kg) and random errors (range: 3.0-3.8kg), no heteroscedasticity of errors (r2 = .053-.082), and trivial effect size (range: -0.17 to 0.04) were observed when the prediction was based on the 2-point method. Although all examined methods reported the 1RM with high reliability (coefficient of variation ≤ 5.1%; intraclass correlation coefficient ≥ .89), the direct method was the most reliable (coefficient of variation < 2.0%; intraclass correlation coefficient ≥ .98). The quick, fatigue-free, and practical 2-point method was able to predict the BP 1RM with high reliability and practically perfect validity, and therefore, the authors recommend its use over generalized group equations.

Differences in the Load-Velocity Profile Between 4 Bench-Press Variants.

To compare the load-velocity relationship between 4 variants of the bench-press (BP) exercise. The full load-velocity relationship of 30 men was evaluated by means of an incremental loading test starting at 17kg and progressing to the individual 1-repetition maximum (1RM) in 4 BP variants: concentric-only BP, concentric-only BP throw (BPT), eccentric-concentric BP, and eccentric-concentric BPT. A strong and fairly linear relationship between mean velocity (MV) and %1RM was observed for the 4 BP variants (r2 > .96 for pooled data and r2 > .98 for individual data). The MV associated with each %1RM was significantly higher in the eccentric-concentric technique than in the concentric-only technique. The only significant difference between the BP and BPT variants was the higher MV with the light to moderate loads (20-70%1RM) in the BPT using the concentric-only technique. MV was significantly and positively correlated between the 4 BP variants (r = .44-.76), which suggests that the subjects with higher velocities for each %1RM in 1 BP variant also tend to have higher velocities for each %1RM in the 3 other BP variants. These results highlight the need for obtaining specific equations for each BP variant and the existence of individual load-velocity profiles.

Strength Behavior of Rocks Under Cyclic Loading

In the present study, the strength behavior of the intact rock subjected to cyclic loading has been studied. A series of laboratory tests has been conducted on intact cylindrical specimens of locally available limestone having the diameter of 40 mm and length to diameter ratio of two. Two different of types of cyclic loading tests has been performed under uniaxial condition. First, a series of incremental cyclic test has been conducted at the loading rate of 0.05, 0.1, 0.2 and 0.4 kN/s to study the change in strength and axial deformation of the rock specimen. Tests have also been performed under constant peak and valley stress to study the effect of the number of cycles and peak stresses on uniaxial strength of rock. From the incremental cyclic loading tests, it has been found that the normalized compressive strength reduces logarithmically with the increase in the rate of loading. From the second type of tests, the effect of peak stress has been found to be more significant than the number of cycles of loading. Empirical correlations have also been presented on the basis of the experimental results to estimate the strength under cyclic loading condition. Damage evolution study has also been conducted to quantify the pre-peak damage occurring in rock specimen when it is subjected to incremental cyclic loading.

Reproducibility of upper leg EMG frequency content during cycling

ABSTRACTReproducibility of frequency content from surface electromyography (sEMG) signals has not been assessed and it is unknown if incremental load testing design could affect sEMG in cycling. The goals of this study were to assess the reproducibility of measures from sEMG frequency content between sessions and to compare these frequency components between a ramp and a step incremental cycling test. Eighteen cyclists performed four incremental load cycling tests to exhaustion. Two tests were performed using a step increment (load started at 100 W for 3 min followed by increments of 30 W every 3 min) and two were performed using a ramp increment (load started at 100 W for 1 min followed by increments of 30 W·min−1). sEMG was monitored bilaterally for the rectus femoris and vastus lateralis throughout the tests and converted into overall activation (whole signal bandwidth), high- and low-frequency contents. The reproducibility of the frequency content ranged from none to strong (ICC = 0.07–0.90). Vastus lateralis activation was larger at the step compared to the ramp test (P < 0.01), without differences for rectus femoris (P = 0.22–0.91) and for the high-frequency (P = 0.28–0.95) and low-frequency contents (P = 0.13–0.94). sEMG from vastus lateralis and rectus femoris presented none to strong reproducibility. Vastus lateralis is more activated in step test design.

Seismic Performance of Precast Polystyrene RC Walls

Precast concrete structure such as precast wall is a concept that is growing rapidly these days. However, the earthquake resistance is believed to be one of its drawbacks. Additionally, the large weight of solid elements also increase the building weight significantly which consequently increase the earthquake base shear force as well. Therefore, investigation on the seismic performance of precast concrete wall has been carried out. Three RC wall specimens using wire mesh reinforcement and EPS (Extended Polystyrene System) panel have been tested. This wall was designed as a structural wall that was capable in sustaining lateral loads (in-plane) yet were lightweight to reduce the total weight of the building. Parameter observed was the ratio of height to width (aspect ratio) of wall of 1.0, 1.5 and 2.0 respectively with the aim to study the behaviour of brittle to ductile transition of the wall. Incremental static load tests were conducted until reaching peak load and then followed by displacement control until failure. Several data were measured at every stage of loading comprising lateral load-displacement behaviour, ultimate strength and collapse mechanism. The outcomes showed that precast concrete walls with a steel wire and EPS panel filler provided considerably good resistance against lateral load.

Isotache model for consolidation with a small incremental load

To examine the applicability of an isotache model, two types of consolidation test were carried out: constant rate of strain (CRS) by changing the strain rate during the test, and an incremental loading (IL) test with small incremental ratios. It is found from the CRS tests that the stress shift caused by the strain rate change is nearly the same for all tested soils, but the behaviour after the change is different: some soils do not follow the isotache model. After selecting two typical soils (one follows the isotache model and the other does not), IL tests with various increment ratios and different durations at the loading stage prior to the incremental load were carried out to investigate how these parameters affect the strain–time relation. It is revealed that the strain–time relation is strongly governed by the magnitude of stress increments; in cases of small increments, most of the settlement is generated after the end of the primary consolidation. It is found that most test results can be interpreted by the isotache model. However, when the load duration at the loading stage prior to the incremental load is longer, the time–strain behaviour differs from that predicted by the isotache model.

Characterisation of Ballina clay

This paper describes a comprehensive characterisation study carried out on clay from the National Soft Soil Testing Facility located at Ballina in northern New South Wales (NSW, Australia). Ballina clay represents the estuarine soft clays of high to extremely high plasticity from the Richmond river valley in NSW. They are structured and lightly overconsolidated with an average organic content around 3%. Index properties as well as mechanical parameters were estimated from laboratory tests performed on tube specimens retrieved using a fixed-piston sampler. Index characterisation tests were combined with constant rate of strain tests, incremental loading tests and stress-path triaxial testing to evaluate compressibility, stiffness, permeability and strength parameters. These deposits display very high compressibility and a low undrained shear strength which is larger in triaxial compression. Ballina clay shows a non-linear stress–strain response either in one-dimensional compression or undrained shearing. The consolidation coefficient, and consequently the water permeability, reduces dramatically with the stress level in the overconsolidated zone, mainly due to soil destructuration. A brittle response has been observed during shearing that reduces the undrained shear strength by around 50% after peak. Geotechnical profiles describing the variation of index and mechanical properties with depth are provided and compared against in situ test results. It is shown that the use of the fixed-piston sampler, in combination with non-destructive methods, to assess and select samples for laboratory testing provided good quality and reliable test results which are in agreement with data interpreted from in situ tests.

Comparison of the force-, velocity-, and power-time curves recorded with a force plate and a linear velocity transducer

This study aimed to correlate, compare, and determine the reliability of force, velocity, and power values collected with a force plate (FP) and a linear transducer during loaded jumps. Twenty-three swimmers performed an incremental loading test at 25, 50, 75, and 100% of their own body weight on a FP. A linear velocity transducer (LVT) was attached to the bar to assess the peak and the mean values of force, velocity, and power. Both the peak variables (r = 0.94 – 0.99 for peak force, r = 0.83 – 0.91 for peak velocity, and r = 0.90–0.94 for peak power; p < 0.001) and the mean variables (r = 0.96–0.99 for mean force, r = 0.87–0.89 for mean velocity, and r = 0.93–0.96 for mean power; p < 0.001) were strongly correlated between both measurement tools. Differences in the shape of the force-, velocity-, and power-time curves were observed. The LVT data showed a steeper increase in these variables at the beginning of the movement, while the FP recorded larger values in the latter part. Peak values were more reliable than mean values. These results suggest that the LVT is a valid tool for the assessment of loaded squat jump.

Excessive training impairs the insulin signal transduction in mice skeletal muscles

The main aim of this investigation was to verify the effects of overtraining (OT) on the insulin and inflammatory signaling pathways in mice skeletal muscles. Rodents were divided into control (CT), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR) groups. Rotarod, incremental load, exhaustive, and grip force tests were used to evaluate performance. Thirty-six hours after the grip force test, the extensor digitorum longus (EDL) and soleus were extracted for subsequent protein analyses. The three OT protocols led to similar responses of all performance evaluation tests. The phosphorylation of insulin receptor beta (pIRβ; Tyr), protein kinase B (pAkt; Ser473), and the protein levels of plasma membrane glucose transporter-4 (GLUT4) were lower in the EDL and soleus after the OTR/down protocol and in the soleus after the OTR/up and OTR protocols. While the pIRβ was lower after the OTR/up and OTR protocols, the pAkt was higher after the OTR/up in the EDL. The phosphorylation of IκB kinase alpha and beta (pIKKα/β; Ser180/181), stress-activated protein kinases/Jun amino-terminal kinases (pSAPK-JNK; Thr183/Tyr185), factor nuclear kappa B (pNFκB p65; Ser536), and insulin receptor substrate 1 (pIRS1; Ser307) were higher after the OTR/down protocol, but were not altered after the two other OT protocols. In summary, these data suggest that OT may lead to skeletal muscle insulin signaling pathway impairment, regardless of the predominance of eccentric contractions, although the insulin signal pathway impairment induced in OTR/up and OTR appeared to be muscle fiber-type specific.