Isoetes candelariensis, a new species of Isoetaceae (Lycopodiidae) from Argentina.

Isoetes candelariensis is a new species of Isoetaceae from Misiones, Argentina. This species is ephemeral, and grows on basaltic bedrock outcrop pools, in Urutau Reserve from Candelaria Department. This taxon differs from other aquatic Isoetes in this region by the unique combination of characters of its leaves, ligule, labium and megaspore ornamentation.

Cross education is modulated by set configuration in knee extension exercise.

OBJECTIVES: The main aim of this study was to determine the effects of set configuration during five weeks of unilateral knee extension resistance training on untrained knee extensors performance. METHODS: Thirty-five subjects were randomly assigned to traditional training (TTG; n=14), rest-redistribution (RRG; n=10) and control group (CON; n=11). TTG and RRG groups trained the dominant knee extensors twice a week with the 10-repetition maximum (RM) load. TTG performed four sets of eight repetitions with three min-rest between sets and RRG 32 repetitions with 17.4 seconds of rest between each one. Before and after interventions, anthropometry, muscle thickness (MT), pennation angle (PA), 1RM, number of repetitions with 10RM pretest load (N10RM), maximum propulsive power (MPP) and maximum voluntary isometric contraction (MVIC) were measured. RESULTS: 1RM of the untrained leg increased only in the TTG group (p<0.001, 10.3% compared with Pre-test). 1RM, MPP and N10RM increased in the trained leg in both TTG (p<0.001) and RRG (p<0.001). No changes occurred in MT or PA. CONCLUSIONS: These results suggest that, when it is not possible to perform bilateral exercises (e.g., leg injury), traditional set configurations should be recommended to improve maximal voluntary force in the untrained leg.

Differences in the effects of a startle stimulus on rate of force development between resistance-trained rock climbers and untrained individuals: Evidence for reticulospinal adaptations?

The aim of the present cross-sectional study was to determine if chronic rock climbing and climbing-specific resistance training (RT) would modify the reticulospinal tract (RST) efficacy. Sixteen healthy, elite level climbers (CL; n = 16, 5 F; 29.8 ± 6.7 years) with 12 ± 7 years of climbing and climbing-specific RT experience and 15 healthy recreationally active participants (CON; n = 15, 4 F; 24.6 ± 5.9 years), volunteered for the study. We quantified RST efficacy by comparing the effects of a startle stimulus over reaction time (Rtime ) and measured rate of force development (RFD) and surface electromyography (sEMG) in representative muscles during powerful hand grip contractions. Both groups performed two Rtime tasks while performing rapid, powerful gripping with the right hand (Task 1) or during 3-s-long maximal voluntary right hand grip contractions in response to an imperative visual signal alone (V), or combined with a auditory-non startle stimulus (A) or/and startling auditory stimulus (S). We also tested the reproducibility of these responses on two separate days in CON. Intersession reliability ranged from 0.34 to 0.96 for all variables. The CL versus CON was 37% stronger (p = 0.003). The S stimulus decreased Rtime and increased RFD and sEMG in both groups during both tasks (all p < 0.001). Rtime was similar between groups in all conditions. However, CL had a greater RFD from 50 to 100 ms compared with CON only after the S stimulus in both tasks (p < 0.05, d = 0.85-0.96). The data tentatively suggest that chronic rock climbing and climbing-specific RT might improve RST efficacy, by increasing RST input to the α-motoneurons.

Altitude-induced effects on neuromuscular, metabolic and perceptual responses before, during and after a high-intensity resistance training session.

PURPOSE: We tested if an acute ascending to 2320 m above sea level (asl) affects corticospinal excitability (CSE) and intracortical inhibition (SICI) measured with transcranial magnetic stimulation (TMS) at rest, before, during and after a traditional hypertrophy-oriented resistance training (RT) session. We also explored whether blood lactate concentration (BLa), ratings of perceived exertion (RPE), perceived muscular pain and total training volume differed when the RT session was performed at hypoxia (H) or normoxia (N). METHODS: Twelve resistance-trained men performed eight sets of 10 repetitions at 70% of one repetition maximum of a bar biceps curl at N (SpO2 = 98.0 ± 0.9%) and H (at 2320 asl, SpO2 = 94.0 ± 1.9%) in random order. Before each session, a subjective well-being questionnaire, the resting motor threshold (rMT) and a single pulse recruitment curve were measured. Before, during and after the RT session, BLa, RPE, muscle pain, CSE and SICI were measured. RESULTS: Before the RT session only the rMT differed between H (- 5.3%) and N (ES = 0.38). RPE, muscle pain and BLa increased through the RT session and were greater at H than N (12%, 54% and 15%, respectively) despite a similar training volume (1618 ± 468 kg vs. 1638 ± 509 kg). CSE was reduced during the RT session (~ 27%) but recovered ten minutes after, regardless of the environmental condition. SICI did not change after any RT session. CONCLUSIONS: The data suggest that acute exposure to moderate hypoxia slightly increased the excitability of the most excitable structures of the corticospinal tract but did not influence intracortical or corticospinal responses to a single RT session.

Longitudinal Effects of Traditional and Rest Redistribution Set Configurations on Explosive-Strength and Strength-Endurance Manifestations.

ABSTRACT: Janicijevic, D, González-Hernández, JM, Jiménez-Reyes, P, Márquez, G, and García-Ramos, A. Longitudinal effects of traditional and rest redistribution set configurations on explosive-strength and strength-endurance manifestations. J Strength Cond Res 37(5): 980-986, 2023-This study aimed to compare the long-term effects of resistance training programs based on traditional and rest redistribution set configurations on explosive-strength and strength-endurance performance of lower-body and upper-body muscles. Thirty physically active men were randomly assigned to a traditional group (TRG: 6 sets of 5 repetitions with 3 minutes of interset rest) or a rest redistribution group (RRG: 30 sets of 1 repetition with 31 seconds of interrepetition rest). The training program lasted 6 weeks (2 sessions·wk -1 ), and in each training session, the squat and bench press exercises were performed with maximal concentric effort against approximately the 75% of the 1 repetition maximum. Before and after training, explosive-strength performance (peak velocity reached at submaximal loads during the countermovement jump and bench press throw) and strength-endurance performance (mean set velocity of 10 repetitions using both traditional and cluster sets in the squat and bench press) were assessed. Significant improvements in all dependent variables were observed after training for both the TRG ( p ≤ 0.004; effect size [ES] = 0.63-3.06) and RRG ( p ≤ 0.001; ES = 0.58-3.23). The magnitude of the changes was comparable for both groups with the only exception of the larger improvements observed in the RRG for the bench press mean set velocity using both traditional (ES = 0.77) and cluster (ES = 0.82) set configurations. Traditional and rest redistribution set configurations are equally effective to improve lower-body explosive strength, lower-body strength endurance, and upper-body explosive strength, whereas rest redistribution set configurations could induce greater adaptations in upper-body strength endurance.

Face Masks at the Gymnasium: Physiological Responses and Mechanical Performance Are Not Compromised by Wearing Surgical or Filtering Facepiece 2 Masks in Healthy Subjects.

ABSTRACT: Rial-Vázquez, J, Nine, I, Guerrero-Moreno, JM, Rúa-Alonso, M, Fariñas, J, Márquez, G, Giráldez-García, MA, Méndez-Bouza, KY, López-Pillado, H, Coutado-Sánchez, E, Losada-Rodríguez, A, and Iglesias-Soler, E. Face masks at the gym: physiological responses and mechanical performance are not compromised by wearing surgical or filtering facepiece 2 masks in healthy subjects. J Strength Cond Res 37(7): 1404-1410, 2023-This study explored the effects of wearing 2 types of face masks on mechanical performance and physiological responses during high-intensity resistance exercise. Twelve healthy men performed 3 workout protocols in a randomized order: wearing a surgical or filtering facepiece 2 (FFP2) mask or without a mask. Each workout consisted of 3 sets of 10 repetitions of bench press (BP) and parallel squat (SQ) with a 12 repetition maximum load, including 2 minutes of recovery between sets and exercises. Mechanical performance was evaluated through the mean propulsive velocity and the number of repetitions completed during each session. Physiological responses were the oxygen saturation (SpO2), blood lactate concentration, heart rate (HR), and HR variability. Perceived exertion was recorded after each set, and The Beck Anxiety Inventory scale was completed at the end of each workout. The number of repetitions completed and the session mean propulsive velocity {(BP [m·s-1]: surgical: 0.35 ± 0.05; FFP2: 0.36 ± 0.04; nonmask: 0.38 ± 0.06) and (SQ: surgical: 0.43 ± 0.05; FFP2: 0.40 ± 0.07; nonmask: 0.41 ± 0.05)} were similar between conditions (p > 0.05). Heart rate recorded during sessions was similar across conditions: surgical: 119 ± 14, FFP2: 117 ± 13, and nonmask: 118 ± 10 bpm (p = 0.919). Face masks had no effect on SpO2, blood lactate concentration, HR variability, perceived exertion, and anxiety values (p > 0.05). Face masks do not compromise strength performance, physiological parameters, and perceived comfort of young and healthy individuals during a high-intensity resistance training session.

Further evidence for the hybrid status of the Brazilian native fern Hypolepis ×paulistana (Dennstaedtiaceae).

Hypolepis ×paulistana was described in 2016 as a putative hybrid, known from a single gathering. The hybrid status of these plants was based solely on the intermediate morphology of the sporophyte, when compared to its presumed parent species. These were thought to be H. stolonifera and H. rugosula, but, H. rigescens (Kunze) T. Moore could not be explicitly ruled out either. In the present work, we tested the hybrid status of Hypolepis ×paulistana adding palynological evidence and by using chloroplast sequences to unambiguously identify the maternal progenitor of the species. We find that sporangia of Hypolepis ×paulistana contain both well-formed spores, as well as spores with morphological and developmental anomalies. The size of the regular spores and the abnormal spores suggest that H. ×paulistana is likely a diploid, and probably infertile hybrid. The ornamentation of the regular spores of H. ×paulistana is similar to that of H. stolonifera. The chloroplast sequences of H. ×paulistana are identical to those of H. stolonifera, as well as their sister position within the global phylogeny of the genus. Thus, we provide new evidence for the hybrid status of H. ×paulistana, and we corroborate the earlier finding that H. stolonifera is the maternal parent.

Amauropelta yabotiensis (Thelypteridaceae), a new species from Biosphere Yabotí Reserve (Misiones, Argentina) and its taxonomic relationships.

The Yabotí Biosphere Reserve (Prov. Misiones, Argentina) with 221,155 ha, represents one of the southernmost relicts of the Paranaense forest. Currently, a project is being developed in the area to inventory and describe the ferns and lycophytes. As a result of these studies, we identify a new species of Amauropelta, A. yabotiensis. Within this genus, it belongs to the group of species with uncinate hairs and presents a unique combination of diagnostic features, including the type of pubescence on the rhizome scales, the shape of the fronds and segments and type of venation. Here, we described and illustrated the species and we analyzed its taxonomic affinities and geographic distribution. Additionally, we provided a distribution map and a key to distinguish it from other Amauropelta species from Misiones province. With this new finding, we highlighted the importance of the Yabotí Reserve as a reservoir of biodiversity in the region.

Psychophysiological Responses During a Cycling Test to Exhaustion While Wearing the Elevation Training Mask.

ABSTRACT: López-Pérez, ME, Romero-Arenas, S, Colomer-Poveda, D, Keller, M, and Márquez, G. Psychophysiological responses during a cycling test to exhaustion while wearing the elevation training mask. J Strength Cond Res 36(5): 1282-1289, 2022-The aim of this study was to investigate the psychophysiological effects of wearing the elevation training mask (ETM). Twelve men performed time-to-exhaustion (TTE) tests at 75% of peak power output with and without wearing the ETM. Heart rate (HR), rating of perceived exertion (RPE), breathing discomfort (BD), and oxygen saturation (SpO2) were measured during the TTE. Prefrontal cortex (PFC) and vastus lateralis oxygenated, deoxygenated, and total hemoglobin were monitored using near-infrared spectroscopy. At the end of each test, blood lactate values (La-) were collected, and subjects completed the Beck Anxiety Inventory (BAI). The mask caused a reduction in the TTE (-37.7%; p < 0.001) and in the SpO2 (-2%; p < 0.001). Beck Anxiety Inventory scores were negatively correlated with the changes observed in the TTE (r = -0.77; p < 0.01). La-, HR, and muscle oxygenation displayed similar results across conditions. In conjunction with an increased hemodynamic response in the PFC, subjects reported higher RPE and BD values in the ETM condition (p < 0.01). Finally, BAI scores were negatively correlated with the changes observed in the TTE (r = -0.77; p < 0.01). This study suggests that wearing the ETM induces psychophysiological alterations affecting the exercise tolerance and limiting the performance.

Effects of Anodal Transcranial Direct Current Stimulation on Training Volume and Pleasure Responses in the Back Squat Exercise Following a Bench Press.

ABSTRACT: Rodrigues, GM, Machado, S, Faria Vieira, LA, Ramalho de Oliveira, BR, Jesus Abreu, MA, Marquez, G, Maranhão Neto, GA, and Lattari, E. Effects of anodal transcranial direct current stimulation on training volume and pleasure responses in the back squat exercise following a bench press. J Strength Cond Res 36(11): 3048-3055, 2022-This study aimed to investigate the effects of anodal transcranial direct current stimulation (a-tDCS) on volume-load and pleasure responses in a back squat following a bench press. Twelve male subjects advanced in resistance training (RT) (age, 25.5 ± 4.4 years) completed 2 experimental trials in a counterbalanced crossover design: a-tDCS and sham conditions. The stimulus was applied over the left dorsolateral prefrontal cortex for 20 minutes using a 2-mA current intensity in a-tDCS condition and 1 minute of active stimulus in the sham condition. Immediately after stimulation, subjects performed the bench press followed by the back squat. The exercise protocol consisted of 3 sets of maximum repetitions at an intensity of 80% of 1 repetition maximum. The volume-load, perceived pleasure, and arousal responses were measured during the RT protocol. The results indicated that volume-load was higher in the a-tDCS condition than in the sham condition for both exercises ( p = 0.02), with large effect for the back squat ( p = 0.045; d = 0.96). The higher volume-load was obtained by increasing the number of repetitions across all sets for the bench press ( p ≤ 0.0001) and only in the first set for the back squat ( p = 0.01). The circumplex model analysis showed a higher pleasure in the bench press and a tendency toward a higher pleasure in the a-tDCS condition. Anodal tDCS may be used as an ergogenic resource for increasing the back squat volume after performing the bench press in resistance-trained male subjects.

Voluntary suppression of associated activity decreases force steadiness in the active hand.

Unilateral muscle contractions are often accompanied by the activation of the ipsilateral hemisphere, producing associated activity (AA) in the contralateral homologous muscles. However, the functional role of AA is not fully understood. We determined the effects of voluntary suppression of AA in the first dorsal interosseous (FDI), on force steadiness during a constant force isometric contraction of the contralateral FDI. Participants (n = 17, 25.5 years) performed two trials of isometric FDI contractions as steadily as possible. In Trial 1, they did not receive feedback or explicit instructions for suppressing the AA in the contralateral homologous FDI. In Trial 2, participants received feedback and were asked to voluntarily suppress the AA in the contralateral nontarget FDI. During both trials, corticospinal excitability and motor cortical inhibition were measured. The results show that participants effectively suppressed the AA in the nontarget contralateral FDI (-71%), which correlated with reductions in corticospinal excitability (-57%), and the suppression was also accompanied by increases in inhibition (27%) in the ipsilateral motor cortex. The suppression of AA impaired force steadiness, but the decrease in force steadiness did not correlate with the magnitude of suppression. The results show that voluntary suppression of AA decreases force steadiness in the active hand. However, due to the lack of association between suppression and decreased steadiness, we interpret these data to mean that specific elements of the ipsilateral brain activation producing AA in younger adults are neither contributing nor detrimental to unilateral motor control during a steady isometric contraction.

Training load but not fatigue affects cross-education of maximal voluntary force.

The purpose of this study was to determine the effects of training load (25% vs. 75% of one repetition maximum [1RM]) and fatigue (failure vs. non-failure) during four weeks of unilateral knee extension resistance training (RT) on maximal voluntary force in the trained and the untrained knee extensors. Healthy young adults (n = 42) were randomly assigned to control (CON, n = 9, 24 ± 4.3 years), low-load RT to failure (LLF, n = 11, 21 ± 1.3 years, three sets to failure at 25% of 1RM), high-load RT to failure (HLF, n = 11, 21 ± 1.4 years, three sets to failure at 75% of 1RM), and high-load RT without failure (HLNF, n = 11, 22 ± 1.5 years, six sets of five repetitions at 75% of 1RM) groups. Before and after the four weeks of training, 1RM, maximal voluntary isometric force, and corticospinal excitability (CSE) were measured. 1RM in the trained (20%, d = 0.70, 15%, d = 0.61) and the untrained knee extensors (5%, d = 0.27, 6%, d = 0.26) increased only in the HLF and HLNF groups, respectively. MVIC force increased only in the trained leg of the HLF (5%, d = 0.35) and HLNF groups (12%, d = 0.67). CSE decreased in the VL of both legs in the HLNF group (-19%, d = 0.44) and no changes occurred in the RF. In conclusion, high- but not low-load RT improves maximal voluntary force in the trained and the untrained knee extensors and fatigue did not further enhance these adaptations. Voluntary force improvements were unrelated to CSE changes in both legs.

Oxygenation Responses While Wearing the Elevation Training Mask During an Incremental Cycling Test.

ABSTRACT: Romero-Arenas, S, López-Pérez, E, Colomer-Poveda, D, and Márquez, G. Oxygenation responses while wearing the elevation training mask during an incremental cycling test. J Strength Cond Res 35(7): 1897-1904, 2021-The Elevation Training Mask 2.0 (ETM) is a commercial training mask that purportedly simulates altitude training, although their effects have not been conclusively demonstrated. Therefore, the purpose of this study was to evaluate the influence of wearing the ETM on muscle and brain oxygenation responses during a maximal incremental cycling test, as well as the influence of this device on the heart rate (HR) response, perception of effort (rating of perceived exertion [RPE]), arterial oxygen saturation (SaO2), blood lactate (La+), and performance (POpeak). Fourteen active males completed an incremental cycling test to volitional exhaustion in 2 separate and counterbalanced conditions, wearing the mask set at 9,000 feet (i.e., 2743 m) and a control condition (CTR, without ETM). During the trial, muscle and cerebral oxygenation were monitored continuously using near-infrared spectroscopy. Heart rate, RPE, and SaO2 were also recorded from the beginning of the test until the volitional exhaustion. La+ was measured at the end of each test. Wearing the ETM significantly reduced the POpeak by -6.9 ± 6.6% (p = 0.002) and this was accompanied by lower La+ values (-12.8 ± 21.6%; p = 0.027). SaO2 was also significantly lower at maximal intensity in comparison with the CTR condition (-1.5 ± 0.3%; p = 0.028). However, both HR and RPE showed a similar trend during both sessions, as well as muscle oxygenation. Nevertheless, the mask caused an increase in brain oxygenation compared with the CTR condition (p < 0.05). In conclusion, our findings suggest that wearing the ETM causes a pronounced increase in O2Hb and tHb in the frontoparietal cortex without any change in the muscle oxygenation.

Transcranial Direct Current Stimulation Does Not Improve Countermovement Jump Performance in Young Healthy Men.

ABSTRACT: Romero-Arenas, S, Calderón-Nadal, G, Alix-Fages, C, Jerez-Martínez, A, Colomer-Poveda, D, and Márquez, G. Transcranial direct current stimulation does not improve countermovement jump performance in young healthy men. J Strength Cond Res 35(10): 2918-2921, 2021-The main purpose of this study was to report the effects of transcranial direct current stimulation (tDCS) on countermovement jump (CMJ) performance in young healthy men. Seventeen healthy male subjects volunteered for the study (age: 22.4 ± 2.6 years; body mass: 71.8 ± 8.7 kg; height: 174.6 ± 5.9 cm; and CMJ height: 36.8 ± 6.3 cm). After a familiarization session, subjects underwent 3 experimental conditions, 7 days apart, in a randomized, double-blinded crossover design: anodal, cathodal, and sham tDCS. The stimulation was applied over the dorsolateral prefrontal cortex for 15 minutes. During experimental sessions, subjects completed a warm-up and 3 CMJ trials separated by 1 minute before and after each of the 3 experimental conditions. Countermovement jump height and muscular peak power were extracted from the best CMJ in each moment. A 2-way repeated-measures analysis of variance with time and condition as factors were performed for CMJ height and muscular peak power. Effect size analysis was conducted using Cohen's d coefficient. The analysis did not show either significant main effects or interactions for both time and condition factors in the CMJ performance (p > 0.05). Furthermore, effect size was trivial for all conditions (d: 0.01-0.14) in CMJ height and muscular peak power. These findings suggest that tDCS may not be a valuable tool to improve vertical jump performance.

Resistance Training to Failure vs. Not to Failure: Acute and Delayed Markers of Mechanical, Neuromuscular, and Biochemical Fatigue.

ABSTRACT: González-Hernández, JM, García-Ramos, A, Colomer-Poveda, D, Tvarijonaviciute, A, Cerón, J, Jiménez-Reyes, P, and Márquez, G. Resistance training to failure vs. not to failure: acute and delayed markers of mechanical, neuromuscular, and biochemical fatigue. J Strength Cond Res 35(4): 886-893, 2021-This study aimed to compare acute and delayed markers of mechanical, neuromuscular, and biochemical fatigue between resistance training sessions leading to or not to failure. Twelve resistance-trained men completed 2 sessions that consisted of 6 sets of the full-squat exercise performed against the 10 repetitions maximum load. In a randomized order, in one session the sets were performed to failure and in the other session the sets were not performed to failure (5 repetitions per set). Mechanical fatigue was quantified through the recording of the mean velocity during all repetitions. The neuromuscular function of the knee extensors was assessed through a maximal voluntary contraction and the twitch interpolation technique before training, immediately after each set, and 1, 24, and 48 hours post-training. Serum creatine kinase (CK) and aspartate aminotransferase (AST) were measured before training and 1, 24, and 48 hours post-training to infer muscle damage. Alpha was set at a level of 0.05. A higher velocity loss between sets was observed during the failure protocol (-21.7%) compared with the nonfailure protocol (-3.5%). The markers of peripheral fatigue were generally higher and long lasting for the failure protocol. However, the central fatigue assessed by the voluntary activation was comparable for both protocols and remained depressed up to 48 hours post-training. The concentrations of CK and AST were higher after the failure protocol revealing higher muscle damage compared with the nonfailure protocol. These results support the nonfailure protocol to reduce peripheral fatigue and muscle damage, whereas the central fatigue does not seem to be affected by the set configuration.

Training intensity-dependent increases in corticospinal but not intracortical excitability after acute strength training.

The purpose of this study was to determine whether the increases in corticospinal excitability (CSE) observed after one session of unilateral isometric strength training (ST) are related to changes in intracortical excitability measured by magnetic brain stimulation (TMS) in the trained and the contralateral untrained biceps brachii (BB) and whether such changes scale with training intensity. On three separate days, 15 healthy young men performed one ST session of 12 sets of eight isometric contractions of the right elbow flexors at 0% (control session), 25%, or 75% of the maximal voluntary contraction (MVC) in a random order. Before and after each session separated at least by 1 week, motor evoked potential (MEP) amplitude, short-interval intracortical inhibition (SICI), contralateral silent period (SP), and intracortical facilitation (ICF) generated by TMS were measured in the trained and the untrained BBs. Compared with baseline, MEPs recorded from the trained BB increased by ~47% after training at 75% of MVC (P < .05) but not after training at 0% (~4%) or 25% MVC (~5%, both P > .05). MEPs in the untrained BB and SICI, SP, and ICF in either BB did not change. Therefore, acute high-intensity but not low-intensity unilateral isometric ST increases CSE in the trained BB without modifications in intracortical inhibition or facilitation. Thus, increases in corticospinal neurons or α-α-motoneuron excitability could underlie the increases in CSE. Regardless of contraction intensity, acute isometric ST did not modify the excitability of the ipsilateral primary motor cortex measured by TMS.

Anodal transcranial direct current stimulation enhances strength training volume but not the force-velocity profile.

PURPOSE: This study aimed to explore the acute effect of transcranial direct current stimulation (tDCS) on the force-velocity relationship, strength training volume, movement velocity, and ratings of perceived exertion. METHODS: Fourteen healthy men (age 22.8 ± 3.0 years) were randomly stimulated over the dorsolateral prefrontal cortex with either ANODAL, CATHODAL or SHAM tDCS for 15 min at 2 mA. The one-repetition maximum (1RM) and force-velocity relationship parameters were evaluated during the bench press exercise before and after receiving the tDCS. Subsequently, participants completed a resistance training session consisting of sets of five repetitions with 1 min of inter-set rest against the 75%1RM until failure. RESULTS: No significant changes were observed in the 1RM or in the force-velocity relationship parameters (p ≥ 0.377). The number of repetitions was higher for the ANODAL compared to the CATHODAL (p = 0.025; ES = 0.37) and SHAM (p = 0.009; ES = 0.47) conditions. The reductions of movement velocity across sets were lower for the ANODAL than for the CATHODAL and SHAM condition (p = 0.014). RPE values were lower for the ANODAL compared to the CATHODAL (p = 0.119; ES = 0.33) and SHAM (p = 0.150; ES = 0.44) conditions. No significant differences between the CATHODAL and SHAM conditions were observed for any variable. CONCLUSION: The application of ANODAL tDCS before a resistance training session increased training volume, enabled the maintenance of higher movement velocities, and reduced RPE values. These results suggest that tDCS could be an effective method to enhance resistance-training performance.

Mechanical, Metabolic, and Perceptual Acute Responses to Different Set Configurations in Full Squat.

González-Hernández, JM, García-Ramos, A, Castaño-Zambudio, A, Capelo-Ramírez, F, Marquez, G, Boullosa, D, and Jiménez-Reyes, P. Mechanical, metabolic, and perceptual acute responses to different set configurations in full squat. J Strength Cond Res 34(6): 1581-1590, 2020-This study aimed to compare mechanical, metabolic, and perceptual responses between 2 traditional (TR) and 4 cluster (CL) set configurations. In a counterbalanced randomized order, 11 men were tested with the following protocols in separate sessions (sets × repetitions [interrepetition rest]): TR1: 3 × 10 [0 seconds]; TR2: 6 × 5 [0 seconds]; CL1: 3 × 10 [10 seconds]; CL2: 3 × 10 [15 seconds]; CL3: 3 × 10 [30 seconds]; CL4: 1 × 30 [15 seconds]. The exercise (full squat), number of repetitions (30), interset rest (5 minutes), and resistance applied (10 repetition maximum) was the same for all set configurations. Mechanical fatigue was quantified by measuring the mean propulsive velocity during each repetition and the change in countermovement jump height observed after each set and after the whole training session. Metabolic and perceptual fatigue were assessed via the blood lactate concentration and the OMNI perceived exertion scale measured after each training set, respectively. The mechanical, metabolic, and perceptual measures of fatigue were always significantly higher for the TR1 set configuration. The 2 set configurations that most minimized the mechanical measures of fatigue were CL2 and CL3. Perceived fatigue did not differ between the TR2, CL1, CL2, and CL3 set configurations. The lowest lactate concentration was observed in the CL3 set configuration. Therefore, both the CL2 and CL3 set configurations can be recommended because they maximize mechanical performance. However, the CL2 set configuration presents 2 main advantages with respect to CL3 (a): it reduces training session duration, and (b) it promotes higher metabolic stress, which, to some extent, may be beneficial for inducing muscle strength and hypertrophy gains.

Alterations in the cortical control of standing posture during varying levels of postural threat and task difficulty.

Cortical excitability increases during the performance of more difficult postural tasks. However, it is possible that changes in postural threat associated with more difficult tasks may in themselves lead to alterations in the neural strategies underlying postural control. Therefore, the purpose of this study was to examine whether changes in postural threat are responsible for the alterations in corticospinal excitability and short-interval intracortical inhibition (SICI) that occur with increasing postural task difficulty. Fourteen adults completed three postural tasks (supported standing, free standing, or standing on an unstable board) at two surface heights (ground level or 3 m above ground). Single- and paired-pulse magnetic stimuli were applied to the motor cortex to compare soleus (SOL) and tibialis anterior (TA) test motor-evoked potentials (MEPs) and SICI between conditions. SOL and TA test MEPs increased from 0.35 ± 0.29 to 0.82 ± 0.41 mV (SOL) and from 0.64 ± 0.51 to 1.96 ± 1.45 mV (TA), respectively, whereas SICI decreased from 52.4 ± 17.2% to 39.6 ± 15.4% (SOL) and from 71.3 ± 17.7% to 50.3 ± 19.9% (TA) with increasing task difficulty. In contrast to the effects of task difficulty, only SOL test MEPs were smaller when participants stood at high (0.49 ± 0.29 mV) compared with low height (0.61 ± 0.40 mV). Because the presence of postural threat did not lead to any additional changes in the excitability of the motor corticospinal pathway and intracortical inhibition with increasing task difficulty, it seems unlikely that alterations in perceived threat are primarily responsible for the neurophysiological changes that are observed with increasing postural task difficulty. NEW & NOTEWORTHY We examined how task difficulty and postural threat influence the cortical control of posture. Results indicated that the motor corticospinal pathway and intracortical inhibition were modulated more by task difficulty than postural threat. Furthermore, because the presence of postural threat during the performance of various postural tasks did not lead to summative changes in motor-evoked potentials, alterations in perceived threat are not responsible for the neurophysiological changes that occur with increasing postural task difficulty.

Neuromuscular and Cardiovascular Adaptations in Response to High-Intensity Interval Power Training.

Romero-Arenas, S, Ruiz, R, Vera-Ibáñez, A, Colomer-Poveda, D, Guadalupe-Grau, A, and Márquez, G. Neuromuscular and cardiovascular adaptations in response to high-intensity interval power training. J Strength Cond Res 32(1): 130-138, 2018-The aim of this study was to determine the efficacy of a high-intensity power training (HIPT) program, and to compare the effects of HIPT to traditional power training (TPT) on the aerobic and power performance. For this purpose, 29 healthy men (23.1 ± 2.7 years) were recruited and randomly distributed into 3 different groups. One group performed TPT (n = 10), the second group performed power training organized as a circuit (HIPT; n = 10), and the third group served as control group (CG; n = 9). Training consisted of weightlifting thrice per week for 6 weeks. The TPT subjects performed 3 to 5 sets of each exercises with interset rest of 90 seconds, and HIPT subjects executed the training in a short circuit (15 seconds of rest between exercises). To know the effects in aerobic performance, maximal aerobic speed (MAS) was measured. To identify the effects on power performance, subjects performed a Wingate test, a countermovement jump (CMJ) test, and a power-load curve in bench press. The main results showed that after both power training protocols, subjects increased significantly (p ≤ 0.05) the power production during the Wingate Test, the height and power reached during the CMJ test, and the peak power produced during the power-load curve. However, only the HIPT group improved significantly MAS (p ≤ 0.05). There were no changes in any variables in CG. Hence, our results suggest that HIPT may be as effective as TPT for improving power performance in young adults. In addition, only HIPT elicited improvements in MAS.