Influence of seagrass meadow length on beach morphodynamics: An experimental study.

A novel flume experiment was conducted to compare the sheltering effect of surrogate seagrass meadows of two different lengths against a bare beach (benchmark). The analyses focused on assessing the impact of meadow cross-shore extent on wave height attenuation, behaviour of wave orbital velocity components, sediment transport, and shoreline erosion. Throughout the tests conducted in the large-scale CIEM wave flume at LIM/UPC Barcelona, meadow density and submergence ratio remained constant, while irregular waves were run over an initial 1:15 sand beach profile. In both meadow layouts, a persistent decrease in wave height from the offshore area in front of the meadow to the breaking zone was found. This reduction was directly correlated with the length of the seagrass meadow. As a result of the reduction in wave energy, less erosion occurred at the shoreline in accordance with the decrease in wave height. The mean velocities exhibited changes in the velocity profile from the meadow area to the immediate zone behind the meadow, a phenomenon not observed in more onshoreward positions. Orbital velocities displayed a reduction exclusively for the long meadow case. This decrease was persistent up to the breaking zone. As a consequence of these changes, the long meadow layout led to a decrease in the volume of sediment transport and a breaker bar closer to the shoreline. The short meadow layout resulted in a higher volume of sediment transport compared to the long meadow layout, although still less than the benchmark layout. Furthermore, in the short meadow layout, the final bar was situated in a location similar to that observed in the benchmark layout.

Applicability of the Load-Velocity Relationship to Predict 1-Repetition Maximum in the Half-Squat in High-Level Sprinters.

PURPOSE: To investigate the indirect measurement of 1-repetition-maximum (1RM) free-weight half-squat in high-level sprinters using the load-velocity relationship. METHODS: Half-squat load and velocity data from 11 elite sprinters were collected in 2 separate testing sessions. Approximately 24 hours prior to the first testing session, sprinters completed a fatiguing high-intensity training session consisting of running intervals, staircase exercises, and body-weight exercises. Prior to the second testing session, sprinters had rested at least 48 hours. Two different prediction models (multiple-point method, 2-point method) were used to estimate 1RM based on the load and either mean or peak concentric velocity data of submaximal lifts (40%-90% 1RM). The criterion validity of all methods was examined through intraclass correlation coefficients, coefficient of variation (CV%), Bland-Altman plots, and the SEM. RESULTS: None of the estimations were significantly different from the actual 1RM. The multiple-point method showed higher intraclass correlation coefficients (.91 to .97), with CVs from 3.6% to 11.7% and SEMs from 5.4% to 10.6%. The 2-point method showed slightly lower intraclass correlation coefficients (.76 to .95), with CVs 1.4% to 17.5% and SEMs from 9.8% to 26.1%. Bland-Altman plots revealed a mean random bias in estimation of 1RM for both methods (mean and peak velocity) ranging from 1.06 to 13.79 kg. CONCLUSION: Velocity-based methods can be used to roughly estimate 1RM in elite sprinters in the rested and fatigued conditions. However, all methods showed variations that limit their applicability for accurate load prescription for individual athletes.

Changes in cerebral blood flow parameters among preterm 30-34 week neonates who are initiated on kangaroo mother care - A prospective analytical observational study.

BACKGROUND: Kangaroo mother care (KMC) is recommended standard of care for preterm neonates. They are vulnerable for cerebral blood flow (CBF) fluctuations linked to intraventricular hemorrhage and periventricular leukomalacia, which have implications on neurodevelopment. This study was designed to document any change in CBF in middle cerebral artery (MCA) of stabilized preterm 30-34 weeks neonates who are initiated on KMC. METHODS: We designed a prospective analytical observational study in a tertiary care neonatal unit. We enrolled 30-34 weeks preterm neonates eligible for KMC after their stabilization (n = 40). CBF was measured in supine position via right MCA Doppler through the temporal window before any KMC, after 2 h of 1st KMC session and following 24 h of 1st session. CBF was quantified in terms of pulsatility index (PI), Resistive Index (RI), peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV) and values were compared against the existing normative values. RESULTS: Mean gestation of study population was 31.91 weeks with a mean birth weight of 1432.75 g. Median day of initiation of KMC was 7 days with mean duration of KMC on day 1 was 4.56 h. We could find statistically significant decrease in the values of PI and RI from 90th centile towards 50th centile of normative values with a mean difference of 0.22 (99 % CI 0.02-0.43, p 0.005) for PI and 0.05 (99 % CI 0.02-0.07, p = 0.000) for RI post the first session of KMC. Following 24 h of 1st KMC session, we could find a significant increase in values of PSV, EDV and MV comparing values of pre-initiation with day 2 pre-KMC but values of PI and RI were not significantly different. CONCLUSION: CBF among 30-34 week preterm neonates tend to optimize after initiation of KMC.

Optimal flow volume measurements in forearm versus arm arteriovenous fistulas.

OBJECTIVES: Successful haemodialysis is dependent on optimal arteriovenous (AV) access flow. Although 600 ml/min is frequently quoted as the critical level for functional flow volume (Qa) according to the National Kidney Foundation guideline, this may not be applicable for the different configurations of AV fistulas (AVF) or AV grafts (AVG). This study evaluates ultrasound derived Qa measurement in the inflow brachial artery to autologous AVF in the forearm radiocephalic and arm brachiocephalic/basilic configurations in relation to significant flow related AV dysfunction. METHODS: Five hundred and eleven duplex ultrasound (DUS) scans were analysed in 193 patients. The end points were therapeutic intervention and/or thrombosis of AVF versus no complication within 3 months of the scan. Receiver operating characteristic (ROC) curves were used to determine the optimal threshold Qa of the brachial artery supplying the AVF. RESULTS: Of the 511 scans, 155 scans were assigned to the intervention group, that is, AVF requiring intervention or thrombosing within 3 months of the DUS. Using ROC curve analysis, the area under the curve (AUC) for all AVF is 0.90 (CI: 0.88-0.93) with an optimal threshold Qa of 686 ml/min. In forearm AVF, the threshold Qa is 589 ml/min while in arm AVF the threshold Qa is 877 ml/min. Forearm Qa is statistically different from arm Qa. CONCLUSION: Forearm AVF Qa threshold at 589 ml/min is distinct from arm AVF Qa at 877 ml/min and these are predictive of the need for impending intervention or thrombosis due to flow-limiting stenosis.

Feasibility of the 2-point method to determine the load-velocity relationship variables during the countermovement jump exercise.

PURPOSE: This study aimed to examine the reliability and validity of load-velocity (L-V) relationship variables obtained through the 2-point method using different load combinations and velocity variables. METHODS: Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads (20 kg, 40 kg, 60 kg, and 80 kg) and a heavy squat against a load linked to a mean velocity (MV) of 0.55 m/s (load0.55). The L-V relationship variables (load-axis intercept (L0), velocity-axis intercept (v0), and area under the L-V relationship line (Aline)) were obtained using 3 velocity variables (MV, mean propulsive velocity (MPV), and peak velocity) by the multiple-point method including (20-40-60-80-load0.55) and excluding (20-40-60-80) the heavy squat, as well as from their respective 2-point methods (20-load0.55 and 20-80). RESULTS: The L-V relationship variables were obtained with an acceptable reliability (coefficient of variation (CV) ≤ 7.30%; intra-class correlation coefficient ≥ 0.63). The reliability of L0 and v0 was comparable for both methods (CVratio (calculated as higher value/lower value): 1.11-1.12), but the multiple-point method provided Aline with a greater reliability (CVratio = 1.26). The use of a heavy squat provided the L-V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load (CVratio: 1.06-1.19). The peak velocity provided the load-velocity relationship variables with the greatest reliability (CVratio: 1.15-1.86) followed by the MV (CVratio: 1.07-1.18), and finally the MPV. The 2-point methods only revealed an acceptable validity for the MV and MPV (effect size ≤ 0.19; Pearson's product-moment correlation coefficient ≥ 0.96; Lin's concordance correlation coefficient ≥ 0.94). CONCLUSION: The 2-point method obtained from a heavy squat load and MV or MPV is a quick, safe, and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L-V relationship.

Prophylactic Hydroxyurea Treatment Is Associated with Improved Cerebral Hemodynamics as a Surrogate Marker of Stroke Risk in Sickle Cell Disease: A Retrospective Comparative Analysis.

Sickle cell disease (SCD) increases the incidence of childhood stroke eighty-fold. Stroke risk can be estimated by measurement of the blood velocity through the middle cerebral artery (MCA) using transcranial doppler ultrasound (TCD). A high MCA blood velocity indicates increased stroke risk due to cerebral vasculopathy, and first-line treatment to prevent primary or recurrent strokes in high-risk children with SCD has classically been chronic blood transfusions. Research has more recently shown that many of these patients may safely transition from transfusions to oral hydroxyurea (HU) treatment while maintaining a decreased risk of stroke. However, the effect on stroke risk of truly prophylactic HU treatment beginning in infancy, prior to the onset of cerebral vasculopathy, is less well understood. Our retrospective study aimed to document the long-term effects of HU treatment compared with no HU treatment in children with SCD, using TCD measurements as our primary outcome and a surrogate marker of stroke risk. Our results showed that when accounting for age-related variability and duration of treatment, prophylactic HU treatment was independently associated with lower TCD MCA velocities compared with no HU treatment, providing further evidence supporting its early initiation for patients with SCD.

A mechanochemical model of the forward/backward movement of motor protein kinesin-1.

Kinesin-1 is an ATP-driven, two-headed motor protein that transports intracellular cargoes (loads) along microtubules. The movement of kinesin-1 has generally been modeled according to its correlation with ATP cleavage (forward movement), synthesis (backward movement), or unproductive cleavage (futile consumption). Based on recent experimental observations, we formulate a mechanochemical model for this movement in which the forward/backward/futile cycle can be realized through multiple biochemical pathways. Our results show that the backward motion of kinesin-1 occurs mainly through backward sliding along the microtubule and is usually also coupled with ATP hydrolysis. We also found that with a low external load, about 80% of ATP is wasted (futile consumption) by kinesin-1. Furthermore, at high ATP concentrations or under high external loads, both heads of kinesin-1 are always in the ATP- or ADP ⋅ Pi-binding state and tightly bound to the microtubule, while at low ATP concentrations and low loads, kinesin-1 is mainly in the one-head-bound state. Unless the external load is near the stall force, the motion of kinesin-1 is almost deterministic.

Impact of morphological parameters on urban ventilation in compact cities: The case of the Tuscolano-Don Bosco district in Rome.

Air pollution and heat stress are major concerns associated with the liveability, resilience and sustainability of cities. They directly affect health and comfort and are associated with augmented morbidity and mortality and an increase in the energy demand for building ventilation, air cleaning and cooling. Nevertheless, the detrimental effects of poor air quality may partly be mitigated by increased urban ventilation. This strategy is closely related to the level of urbanization and the urban morphology. Therefore, detailed investigations on the impact of different morphologies on urban ventilation are of paramount importance. Computational Fluid Dynamics simulations have been widely used during the last decades to investigate the effects of the urban morphology on the urban ventilation. However, most of these studies focused on idealized building arrangements, while detailed investigations about the role of real urban morphologies are scarce. This study investigates the ventilation in a compact area in the city of Rome, Italy. 3D steady-state Reynolds-averaged Navier-Stokes simulations are performed to analyze the impact of Morphological Parameters (MP) on the urban ventilation. The results show a considerable worsening of urban ventilation with increasing building density with a reduction in the mean wind velocity up to 62% experienced at the pedestrian level (zp). Correlations between five MPs, e.g., plan area density, area-weighted mean building height, volume density, façade area density, and non-dimensional mean velocity at pedestrian level and at 10 m height are evaluated, and simple models are obtained using linear regression analysis. Among the selected MPs, the building façade area density shows a remarkable correlation with the non-dimensional mean velocity at zp (R2 = 0.82). Such correlations can be valuable tools for practitioners and urban designers, particularly during the first stage of planning, for highlighting areas potentially vulnerable to poor air conditions without running computationally expensive simulations.

Receiver operating characteristic curve analysis of arteriovenous dialysis access flow using ultrasound.

BACKGROUNDS: Despite numerous studies investigating the use of ultrasound (US) in assessing arteriovenous fistulas (AVF), there are no universally agreed threshold flow velocities in diagnosing significantly abnormal flow that are useful in predicting thrombotic flow-related dysfunction. This study evaluates a predictive model using receiver operating characteristic curve (ROC) analyses to establish threshold velocities. METHODS: Five hundred and eleven US scans were analysed. ROC curves were used to determine the optimal threshold time average mean velocity (TAMV), peak systolic velocity (PSV) and end diastolic velocity (EDV) of the brachial artery supplying the AVF in determining the need for intervention or thrombosis within 3 months of the scans. Estimated flow volume (FV) ROC was used as an evaluative comparison. RESULTS: There were 356 negative and 155 positive scan results in relation to the need for intervention or thrombosis. Empirical flow velocity parameters of TAMV, EDV and PSV were analysed using ROC curves, yielding an area under the curve (AUC) of 0.95, 0.92 and 0.86, respectively. FV ROC analysis yields a comparative AUC of 0.90. A TAMV cut-off at 48.6 cm/s yielded the highest AUC. Subgroup analysis yielded an optimal TAMV cut-off of 45 cm/s for forearm and 49 cm/s for arm AVF. The EDV was also highly predictive of outcomes. PSV has the lowest accuracy. CONCLUSION: The TAMV of inflow brachial artery to AVF is highly predictive of outcomes of thrombotic flow-related dysfunction. Our study confirms TAMV cut-offs of 45 cm/s for forearm and 49 cm/s for arm AVF. These results require prospective validation.

Velocity transformation for compressible wall-bounded turbulent flows with and without heat transfer.

In this work, a transformation, which maps the mean velocity profiles of compressible wall-bounded turbulent flows to the incompressible law of the wall, is proposed. Unlike existing approaches, the proposed transformation successfully collapses, without specific tuning, numerical simulation data from fully developed channel and pipe flows, and boundary layers with or without heat transfer. In all these cases, the transformation is successful across the entire inner layer of the boundary layer (including the viscous sublayer, buffer layer, and logarithmic layer), recovers the asymptotically exact near-wall behavior in the viscous sublayer, and is consistent with the near balance of turbulence production and dissipation in the logarithmic region of the boundary layer. The performance of the transformation is verified for compressible wall-bounded flows with edge Mach numbers ranging from 0 to 15 and friction Reynolds numbers ranging from 200 to 2,000. Based on physical arguments, we show that such a general transformation exists for compressible wall-bounded turbulence regardless of the wall thermal condition.

Mental Fatigue From Smartphone Use Reduces Volume-Load in Resistance Training: A Randomized, Single-Blinded Cross-Over Study.

We investigated the acute effects of mental fatigue induced by 30-minute use of smartphone social network apps on volume load in resistance training among recreationally trained adults. Sixteen (n = 16) adults of both sexes performed three sets of a half back-squat exercise to failure with 80% of 15RM, interspersed with 3-minutes of passive recovery between sets, before and after two different cognitive tasks: (a) use of smartphone social network apps; and (b) watching a documentary. We assessed mechanical variables and ratings of perceived exertion during the strength exercise. Relative to the documentary-viewing control condition, a 30-minute exposure to smartphone social network apps led participants toward increased perception of mental fatigue (p = 0.004) and lower volume-load during the strength exercise (p = 0.006). There were no significant differences in perceived exertion between conditions (p = 0.54), participants' motivation (p = 0.277), intra-set mechanical variables (p > 0.05), or blood lactate concentrations (p = 0.36). Our findings of an isolated possible higher-than normal RPE without changes in physiological variables, accompanying the lower volume-load in the mentally-fatigued participants support psychological, rather than physiological, bases for mental fatigue effects.

Zooming in on cerebral small vessel function in small vessel diseases with 7T MRI: Rationale and design of the "ZOOM@SVDs" study.

Background: Cerebral small vessel diseases (SVDs) are a major cause of stroke and dementia. Yet, specific treatment strategies are lacking in part because of a limited understanding of the underlying disease processes. There is therefore an urgent need to study SVDs at their core, the small vessels themselves. Objective: This paper presents the rationale and design of the ZOOM@SVDs study, which aims to establish measures of cerebral small vessel dysfunction on 7T MRI as novel disease markers of SVDs. Methods: ZOOM@SVDs is a prospective observational cohort study with two years follow-up. ZOOM@SVDs recruits participants with Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL, N = 20), sporadic SVDs (N = 60), and healthy controls (N = 40). Participants undergo 7T brain MRI to assess different aspects of small vessel function including small vessel reactivity, cerebral perforating artery flow, and pulsatility. Extensive work-up at baseline and follow-up further includes clinical and neuropsychological assessment as well as 3T brain MRI to assess conventional SVD imaging markers. Measures of small vessel dysfunction are compared between patients and controls, and related to the severity of clinical and conventional MRI manifestations of SVDs. Discussion: ZOOM@SVDs will deliver novel markers of cerebral small vessel function in patients with monogenic and sporadic forms of SVDs, and establish their relation with disease burden and progression. These small vessel markers can support etiological studies in SVDs and may serve as surrogate outcome measures in future clinical trials to show target engagement of drugs directed at the small vessels.

Assessment of the loaded squat jump and countermovement jump exercises with a linear velocity transducer: which velocity variable provides the highest reliability?

This study aimed to compare the between-session reliability of three typically measured velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and maximum velocity [Vmax]) to assess vertical jump performance. Totally, 23 men had their squat jump (SJ) and countermovement jump (CMJ) tested against five different loading conditions (17, 30, 45, 60 and 75 kg) during two consecutive weeks. The two sessions of each jump type were performed within the same week separated by 48-72 h. The main finding was a significant difference in reliability between the variables, which were ranked from the highest to the lowest reliable as follows (median coefficient of variation [CV] and range): Vmax (CV = 2.35% [1.85%-3.23%]) >MV (CV = 3.29% [2.18%-4.40%]) >MPV (CV = 3.69% [2.08%-5.17%]). A significant variable × exercise interaction was also observed showing that the differences in reliability between the variables were meaningful during the SJ (MV: CV = 3.93% [3.06%-4.40%], MPV: CV = 4.61% [4.07%-5.17%], and Vmax: CV = 2.14% [1.85%-2.71%]), while no significant differences were observed for the CMJ (MV: CV = 2.43% [2.18%-3.70%], MPV: CV = 2.71% [2.08%-3.63%], and Vmax: CV = 2.40% [1.97%-3.23%]). These results suggest that the Vmax should be the recommended variable for obtaining a reproducible measure of lower-body ballistic performance, especially during the SJ exercise.

Doppler-based predictive model for methotrexate resistance in low-risk gestational trophoblastic neoplasia with myometrial invasion: prospective study of 147 patients.

OBJECTIVES: This prospective clinical study aimed to evaluate the vascularization characteristics of low-risk gestational trophoblastic neoplasia (GTN) using Doppler imaging and to develop a predictive model for resistance to methotrexate (MTX). METHODS: Patients with low-risk GTN receiving primary MTX treatment were enrolled from the Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China, from September 2012 to August 2018. The primary endpoint was to develop and internally validate a predictive model for resistance to MTX therapy in these patients. In the training set, clinical features and Doppler hemodynamic parameters before MTX therapy were analyzed using logistic regression to identify independent predictors of MTX resistance, which were integrated into the model. The predictive performance of the model was evaluated by leave-one-out cross-validation in the training dataset and internal validation in an independent-sample test dataset. RESULTS: The entire imaging protocol was completed by 147 eligible patients, of which 110 comprised the training set and 37 the test set. In the training set, cases with myometrial invasion (81.8%; 90/110) showed vascular-enriched areas in the myometrium and high velocity and low impedance ratios of the uterine artery (UtA) compared to cases without myometrial invasion (18.2%; 20/110). On multivariate logistic regression analysis, time-averaged mean velocity in UtA (UtA-TAmean) and the International Federation of Gynecology and Obstetrics (FIGO) score were identified as independent predictors (P = 0.009 and P = 0.043, respectively) of MTX resistance. The Doppler-based predictive model, developed based on the 90 cases with myometrial invasion, was y = -2.95332 + 0.41696 × FIGO score + 0.03551 × UtA-TAmean. The model showed an area under the curve of 0.757 (95% CI, 0.653-0.862) and the optimal cut-off value was 0.50622, which had 45.2% sensitivity and 96.6% specificity. The model stratified patients with low-risk GTN into low (< 10%), intermediate (10-90%) and high (> 90%) probability of MTX resistance, based on the threshold values of -1.59544 and 0.10046. The model had an accuracy of 74.4% (95% CI, 64.5-82.3%) in the cross-validation and 72.7% (95% CI, 55.8-84.9%) in the internal validation. CONCLUSIONS: The Doppler-based predictive model, combining a non-invasive marker of tumor vascularity with the FIGO scoring system, can differentiate cases with low from those with high probability of developing MTX resistance and therefore has the potential to guide treatment options in patients with low-risk GTN and myometrial invasion. © 2020 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Transcranial Doppler Evaluation of the Cerebral Vasculature in Women Patients who Have Migraine with Aura.

BACKGROUND: Previous studies suggest that increased cerebrovascular reactivity might be a feature of patients who have migraine with aura (MwA). The correlation between the clinical presentation of migraine with aura and transcranial Doppler parameters remains unclear. OBJECTIVE: The main aim of this study was to explore cerebral blood flow, vascular resistance, and cerebrovascular reactivity in women MwA. Also, the relationships between hemodynamic conditions and aura characteristics are examined. DESIGN: Cross-sectional study. SETTING: Headache Center, Neurology Clinic, Clinical Center of Serbia. SUBJECTS: Fifty-four women MwA and 49 healthy controls (HCs). METHODS: Transcranial Doppler sonography examination was used to determine blood flow mean velocity (MV) and pulsatility index (PI), as well as breath-holding index (BHI), in 15 arterial segments comprising the circle of Willis. RESULTS: A total of 54 women MwA and 49 HCs were studied. The PIs of all segments of the left and right middle cerebral arteries and the left and right anterior cerebral arteries were significantly higher in MwA with regards to HCs. Also, both the left and right BHIs were significantly higher in MwA than HCs. In addition, MVs of the right vertebral artery and the first segment of the basilar artery were significantly lower in MwA than HCs. Longer duration of migraine aura showed a weak negative correlation with the PI of the left posterior cerebral artery. CONCLUSIONS: Our findings suggest increased vessel pulsatility, abnormal cerebrovascular reactivity, and decreased cerebral blood flow velocity in several arterial segments of the Willis circle in women MwA.

Push-Ups are Able to Predict the Bench Press 1-RM and Constitute an Alternative for Measuring Maximum Upper Body Strength Based on Load-Velocity Relationships.

The aims of this study were firstly to compare the similarity in upper-body muscle activation between the bench press and push-up at similar loads, and secondly to establish a 1-RM prediction equation between the two exercises based upon the load-velocity relationship. Twenty resistance-trained male athletes (age 22.5 ± 5.24 years, body mass 83.7 ± 10.7 kg, body height 1.80 ± 0.06 m) performed push-ups and bench presses with four different loads. Push-ups were performed without a weight vest and with a 10-20-30 kg weight vest. Bench presses were performed at 50-80% of athletes' assumed 1 repetition max (1-RM) in 10 kg steps, while a linear encoder measured performance during the exercises. A load-velocity relationship was established as a product of the load and velocity for the push-up and bench press per participant and the equation was used to establish a predicted 1-RM. Mean muscle activation of eight upper body muscles was recorded for each exercise and each load. The main findings of this study demonstrate an extremely large association between the predicted 1-RM loads performed with the push-up and bench press (r = 0.93) in experienced resistance trained men. Furthermore, most muscles showed similar activations between the two exercises with the different loads except the deltoid and biceps brachii muscles. It may be concluded that it is possible to predict a cross-over 1-RM between the two exercises based upon the load-velocity relationship in each exercise, and that training push-ups largely targets the same muscles as the bench press except the deltoid and biceps muscles. For coaches and athletes, the use of this method is a low cost and time-effective alternative for standard 1-RM bench press testing to predict maximal upper body strength.

ADOR2A C Allele Carriers Exhibit Ergogenic Responses to Caffeine Supplementation.

Caffeine's ergogenic effects on exercise performance are generally explained by its ability to bind to adenosine receptors. ADORA2A is the gene that encodes A2A subtypes of adenosine receptors. It has been suggested that ADORA2A gene polymorphisms may be responsible for the inter-individual variations in the effects of caffeine on exercise performance. In the only study that explored the influence of variation in ADORA2A-in this case, a common polymorphism (rs5751876)-on the ergogenic effects of caffeine on exercise performance, C allele carriers were identified as "non-responders" to caffeine. To explore if C allele carriers are true "non-responders" to the ergogenic effects of caffeine, in this randomized, double-blind study, we examined the acute effects of caffeine ingestion among a sample consisting exclusively of ADORA2A C allele carriers. Twenty resistance-trained men identified as ADORA2A C allele carriers (CC/CT genotype) were tested on two occasions, following the ingestion of caffeine (3 mg/kg) and a placebo. Exercise performance was evaluated with movement velocity, power output, and muscle endurance during the bench press exercise, countermovement jump height, and power output during a Wingate test. Out of the 25 analyzed variables, caffeine was ergogenic in 21 (effect size range: 0.14 to 0.96). In conclusion, ADORA2A (rs5751876) C allele carriers exhibited ergogenic responses to caffeine ingestion, with the magnitude of improvements similar to what was previously reported in the literature among samples that were not genotype-specific. Therefore, individuals with the CT/CC genotype may still consider supplementing with caffeine for acute improvements in performance.

Influence of the grip width on the reliability and magnitude of different velocity variables during the bench press exercise.

This study aimed to compare the within-session reliability and magnitude of velocity variables recorded against a range of submaximal loads during the bench press (BP) exercise performed in a Smith machine using different grip widths. Sixteen physically active men (BP one-repetition maximum [1RM] relative to body mass = 1.01 ± 0.19 kg·kg-1) were randomly tested on 4 sessions using a close grip width (100% of biacromial width), medium grip width (150% of biacromial width), wide grip width (200% of biacromial width), and self-selected grip width (176 ± 17% of biacromial width). Mean velocity (MV), maximum velocity (Vmax), and vertical displacement were recorded with a linear velocity transducer against the 35%1RM, 55%1RM, and 75%1RM. The main findings revealed that (I) the self-selected was the only grip width with an acceptable reliability for all loads and velocity variables (CV ≤ 7.56%; ICC ≥ 0.82), (II) the medium grip width provided the highest reliability for MV (CV ratio ≥ 1.20), while a comparable reliability was observed for Vmax using the close, medium and self-selected grip widths (CV ratio ≤ 1.08), (III) the Vmax showed the highest reliability for all grip widths (CV ratio = 1.68), and (IV) the MV and vertical displacement of the barbell were generally higher for narrow grip widths (close and medium) compared to the wide and self-selected grip widths, while no significant differences between the grip widths were observed for Vmax (p > .05). Taken together, we recommend the assessment of Vmax using a self-selected grip width during the routine testing of BP performance against submaximal loads.

Validity and Reliability of Kinematics Measured with PUSH Band vs. Linear Encoder in Bench Press and Push-Ups.

BACKGROUND: The aim of this study was to compare the validity and reliability of a PUSH band device with a linear encoder to measure movement velocity with different loads during the push-up and bench press exercises. METHODS: Twenty resistance-trained athletes performed push-up and bench press exercises with four different loads: without weight vest, 10-20-30 kg weight vest, bench press: 50-82% of their assumed 1 repetition maximum (1 RM) in steps of 10 kg. A linear encoder (Musclelab) and the PUSH band measured mean and peak velocity during both exercises. Several statistical analyses were used to investigate the validity and reliability of the PUSH band with the linear encoder. RESULTS: The main findings of this study demonstrated only moderate associations between the PUSH band and linear encoder for mean velocity (r = 0.62, 0.70) and peak velocity (r = 0.46, 0.49) for both exercises. Furthermore, a good level of agreement (peak velocity: ICC = 0.60, 0.64; mean velocity: ICC = 0.77, 0.78) was observed between the two measurement devices. However, a significant bias was found with lower velocity values measured with the PUSH band in both exercises. In the push-up, both the linear encoder and PUSH band were deemed very reliable (ICC > 0.98; the coefficient of variation (CV): 5.9-7.3%). Bench press reliability decreased for the PUSH band (ICC < 0.95), and the coefficient of variance increased to (12.8-13.3%) for the velocity measures. Calculated 1 RM with the two devices was the same for the push-up, while in bench press the PUSH band under-estimated the 1 RM by 14 kg compared to the linear encoder. CONCLUSIONS: It was concluded that the PUSH band will show decreased reliability from velocity measures in a bench press exercise and underestimate load-velocity based 1 RM predictions. For training, the PUSH band can be used during push-ups, however caution is suggested when using the device for the purposes of feedback in bench press at increasing loads.