Absolute Load Research Articles

Load-dependent mechanical demands of the lower extremity during the back and front squat

ABSTRACT The purpose of this study was to examine load-dependent differences in lower-extremity biomechanics between the back squat (BS) and front squat (FS) exercises. Eleven NCAA Division-I athletes performed three repetitions of the BS and FS at loads of 40%, 60%, and 80% of their FS one repetition maximum (FS-1RM). Kinematic and kinetic data were collected during each squat repetition and used to calculate lower extremity peak joint angles and peak net joint moments (NJM). Peak angles and NJM were compared with a 2 × 3 repeated measures ANOVA. Peak hip extensor NJM were greater during the BS at 60% and 80% of FS-1RM. In comparison, peak knee extensor NJM were greater during the FS at 80% of FS-1RM. However, regression-based prediction of NJM at 100% of FS and BS 1RM indicated that at maximal loads, peak knee NJM are (~3%) higher during the BS. The experimental results suggest that when performed at the same absolute load, the BS and FS are characterized by greater respective mechanical demands imposed on the hip and knee extensors muscles groups. However, prediction-based results suggest that the knee extensor NJM demands are comparable when performed at the same relative load (i.e., with respect to each exercise’s RM).

Loading applied on osseointegrated implant by transtibial bone-anchored prostheses during daily activities: Preliminary characterization of prosthetic feet.

ABSTRACT Introduction This case series study laid out principles for characterization of loading profile applied on osseointegrated implant by transtibial bone-anchored prostheses fitted with various feet while presenting benchmark loading data. Materials and Methods Three individuals walked and ascended and descended stairs and ramps with instrumented prostheses fitted with a load cell as well as usual and anthropomorphic feet successively. The characterization of the loading profile involved the comparison of 100 variables including spatiotemporal characteristics, loading boundaries, local extremum, and impulse. Results The absolute maximum load extracted from 319 gait cycles (GCs) with both prostheses across all activities was 48 %BW, 17 %BW, and 112 %BW for the forces as well as 2 %BWm, 13 %BWm, and 1 %BWm for the moments on and around the anteroposterior, mediolateral, and long axes of the implant, respectively. Discussion New evidence presented here indicated that a specific and comprehensive loading characterization capable of differentiating transtibial bone-anchored prostheses was achievable when relying on triaxial direct measurements, recording a range of daily activities in addition to walking, and considering at least nine loading extremum. Conclusions Prosthetic care providers could use this characterization for evidence-based fitting of components to the growing population of individuals with transtibial amputation fitted with osseointegrated implants worldwide.

Combining whole-genome shotgun sequencing and rRNA gene amplicon analyses to improve detection of microbe\u2013microbe interaction networks in plant leaves

Microorganisms from all domains of life establish associations with plants. Although some harm the plant, others antagonize pathogens or prime the plant immune system, support the acquisition of nutrients, tune plant hormone levels, or perform additional services. Most culture-independent plant microbiome research has focused on amplicon sequencing of the 16S rRNA gene and/or the internal transcribed spacer (ITS) of rRNA genomic loci, which show the relative abundance of the microbes to each other. Here, we describe shotgun sequencing of 275 wild Arabidopsis thaliana leaf microbiomes from southwest Germany, with additional bacterial 16S and eukaryotic ITS1 rRNA amplicon data from 176 of these samples. Shotgun data, which unlike the amplicon data capture the ratio of microbe to plant DNA, enable scaling of microbial read abundances to reflect the microbial load on the host. In a more cost-effective hybrid strategy, we show they also allow a similar scaling of amplicon data to overcome compositionality problems. Our wild plants were dominated by bacterial sequences, with eukaryotes contributing only a minority of reads. Microbial membership showed weak associations with both site of origin and plant genotype, both of which were highly confounded in this dataset. There was large variation among microbiomes, with one extreme comprising samples of low complexity and a high load of microorganisms typical of infected plants, and the other extreme being samples of high complexity and a low microbial load. Critically, considering absolute microbial load led to fundamentally different conclusions about microbiome assembly and the interaction networks among major taxa.

Maximal Strength, Muscle Activation, and Bar Velocity Comparisons Between Squatting With a Traditional or Safety Squat Bar.

Vantrease, WC, Townsend, JR, Sapp, PA, Henry, RN, and Johnson, KD. Maximal strength, muscle activation, and bar velocity comparisons between squatting with a traditional or safety squat bar. J Strength Cond Res 35(2S): S1-S5, 2021-The purpose of this study was to compare strength, muscle activation, and bar velocity between the traditional (TRAD) and safety squat bar (SSB) back squat. Thirty-two men (21.94 ± 3.1 years, 1.78 ± 0.8 m, 81.7 ± 10.1 kg) volunteered to complete this randomized, crossover-design study. Subjects completed 2 separate 1 repetition maximum (1RM) sessions using either the TRAD or SSB. Subsequently, subjects completed 1 session of 3 repetitions at 65 and 85% of their 1RM for each squat condition (SSB & TRAD). Peak muscle activation of 7 muscles from the lower body and trunk was recorded through surface electromyography (EMG), and mean velocity (MV) was recorded by a linear transducer. Electromyography and MV were analyzed by a 2 × 2 (bar × load) repeated-measures analysis of variance. A Pearson correlation was used to determine the relationship of 1RM load between bars. Squat 1RM was significantly higher (p < 0.001; 11.6%) for TRAD (144.7 kg) compared with SSB (128.8 kg), and a strong correlation (r = 0.94) was observed between 1RM values of each bar. A significant main effect was seen in EMG (p < 0.001) and MV for load (p < 0.001). No significant bar × load interaction was observed between conditions for any EMG or bar velocity measure (p > 0.05). The SSB produces similar muscle activation and bar velocities compared with the TRAD at relative intensities. However, absolute loads should be adjusted when changing squat bars during a training cycle.

Insect herbivory reshapes a native leaf microbiome.

Insect herbivory is pervasive in plant communities, but its impact on microbial plant colonizers is not well-studied in natural systems. By calibrating sequencing-based bacterial detection to absolute bacterial load, we find that the within-host abundance of most leaf microbiome (phyllosphere) taxa colonizing a native forb is amplified within leaves affected by insect herbivory. Herbivore-associated bacterial amplification reflects community-wide compositional shifts towards lower ecological diversity, but the extent and direction of such compositional shifts can be interpreted only by quantifying absolute abundance. Experimentally eliciting anti-herbivore defences reshaped within-host fitness ranks among Pseudomonas spp. field isolates and amplified a subset of putatively phytopathogenic P. syringae in a manner causally consistent with observed field-scale patterns. Herbivore damage was inversely correlated with plant reproductive success and was highly clustered across plants, which predicts tight co-clustering with putative phytopathogens across hosts. Insect herbivory may thus drive the epidemiology of plant-infecting bacteria as well as the structure of a native plant microbiome by generating variation in within-host bacterial fitness at multiple phylogenetic and spatial scales. This study emphasizes that 'non-focal' biotic interactions between hosts and other organisms in their ecological settings can be crucial drivers of the population and community dynamics of host-associated microbiomes.

Low-Velocity Loss Induces Similar Strength Gains to Moderate-Velocity Loss During Resistance Training.

Galiano, C, Pareja-Blanco, F, Hidalgo de Mora, J, and Sáez de Villarreal, E. Low-velocity loss induces similar strength gains to moderate-velocity loss during resistance training. J Strength Cond Res 36(2): 340-345, 2022-This study aimed to analyze the effects of 2 velocity-based resistance training (VBT) programs that used the same relative loading but differed in the velocity loss (VL) throughout the set: 5% (VL5) vs. 20% (VL20). Twenty-eight physically active men (age: 23.0 ± 3.2 years; height: 175.8 ± 4.7 cm; body mass: 73.8 ± 10.8 kg) were randomly assigned to 2 groups: VL5 (n = 15) or VL20 (n = 13). Subjects followed a 7-week (14 sessions) VBT program using the squat exercise while repetition velocity was monitored. The following variables were assessed at pretest and posttest: estimated 1-repetition maximum (1RM); average velocity attained for all absolute loads common to pretest and posttest (AV); average velocity for those loads that were moved faster than 1 m·s-1 (AV > 1); average velocity for those loads that were moved slower than 1 m·s-1 (AV < 1); countermovement jump (CMJ); and 20-m running sprint time (T20). T20 and CMJ height were assessed before each training session to analyze their evolution during the training program. The VL5 group executed only 32.6% of the total repetitions performed by the VL20 group (156.9 ± 25.0 vs. 480.5 ± 162.0 rep). Both groups improved significantly (p < 0.01) in all variables analyzed (1RM, AV, AV > 1, AV < 1, CMJ, and T20) from pretest to posttest, with no significant differences between them. Therefore, a low VL (5%) induced similar gains in strength, jump, and sprint performance to a moderate VL of 20%, despite VL5 performing only 32.6% of the repetitions achieved by the VL20 group.

The range of motion of the back squat exercise affects absolute volume load without changing the rating of perceived exertion

Abstract The range of motion (ROM) may affect the external maximal load during back squat (BS) exercise. The correct ROM manipulation can be useful as an exercise load manipulation strategy, changing the volume load during a resistance training session. The aim of this study was to evaluate the acute effects of ROM on relative load, absolute load and the rating of perceived exertion (RPE) during partial and full BS exercise with adjusted loads. Fifteen male individuals (age: 26.5±4.5 years; height: 173±6 cm; body mass: 80.6 ± 8.8 kg; resistance training experience 5±3 years) participated in this study. The experimental procedure was conducted in two sessions. In the first session, brief familiarization and a 10-repetition maximal test (10-RM) was performed for partial (PBS) and full BS exercise (FBS) with 30-min of rest interval. During the second session, all subjects performed 1 set of 10-RM in both conditions (partial and full ROM), and relative load, absolute load, and RPE were evaluated. A paired t-test was used to compare means. The results showed higher values for PBS when compared to FE exercise: relative load (PBS: 1.14±0.24xBW vs. FBS: 0.87±0.24xBW; P&lt;0.001), and absolute load (PBS: 925±249 kg x FBS: 708±232 kg, P&lt;0.001). Similar RPE was observed between conditions (PBS: 8.6±1.3 IEP x FBS: 8.5±1.0 IEP, P=0.855). It was concluded that PBS allowed higher relative load and absolute load during 10RM, without effects on RPE.

Profile of hematological abnormalities and its correlation with absolute CD4 count and human immunodeficiency virus viral load in human immunodeficiency virus-infected patients in a tertiary care hospital

Background:A variety of hematological manifestations are seen at every stage of human immunodeficiency virus (HIV) infection, and they often pose a great challenge in the comprehensive management of acquired immunodeficiency syndrome. Anemia is the most common hematological abnormality associated with HIV infection. The severity and the incidence of cytopenia are usually correlated with the stage of the disease and underlying immune status if interpreted cautiously, especially if the patient is on regular follow-up. The primary objective of the present study was to understand the spectrum of hematological abnormalities in HIV-infected patients, whereas the secondary objective was to evaluate the correlation of hematological abnormalities with absolute CD4 count and HIV viral load.Materials and Methods:The present cross-sectional descriptive study was conducted on 100 patients, aged 18 years and above, diagnosed with HIV infection and confirmed by Western blot or ELISA method. Both inpatients and outpatients at our tertiary care hospital were included in the study.Results:Individuals with high viral load and low CD4 count had a higher prevalence of anemia. There was a statistically significant and directly proportionate decrease in the absolute CD4 count as the hemoglobin levels decreased (P = 0.004). In the present study, normocytic normochromic blood picture and anemia of chronic disease blood picture were more prevalent among the study participants. Individuals with high viral load and CD4 count <200 cells/mm3 had a higher rate of occurrence of coinfections. The correlation of absolute neutrophil count and thrombocytopenia with absolute CD4 count and HIV viral load was not statistically significant.Conclusions:Complete blood counts and peripheral smear observations were significantly correlated with high HIV viral load and lower absolute CD4 cell counts and therefore can be suggested as economical alternatives for the evaluation of the status of HIV disease stage and its progression.

Gut microbiota structure differs between honeybees in winter and summer

Adult honeybees harbor a specialized gut microbiota of relatively low complexity. While seasonal differences in community composition have been reported, previous studies have focused on compositional changes rather than differences in absolute bacterial loads. Moreover, little is known about the gut microbiota of winter bees, which live much longer than bees during the foraging season, and which are critical for colony survival. We quantified seven core members of the bee gut microbiota in a single colony over 2 years and characterized the community composition in 14 colonies during summer and winter. Our data show that total bacterial loads substantially differ between foragers, nurses, and winter bees. Long-lived winter bees had the highest bacterial loads and the lowest community α-diversity, with a characteristic shift toward high levels of Bartonella and Commensalibacter, and a reduction of opportunistic colonizers. Using gnotobiotic bee experiments, we show that diet is a major contributor to the observed differences in bacterial loads. Overall, our study reveals that the gut microbiota of winter bees is remarkably different from foragers and nurses. Considering the importance of winter bees for colony survival, future work should focus on the role of the gut microbiota in winter bee health and disease.

The role of stiffness variation in switches and crossings: Comparison of vehicle–track interaction models with field measurements

The performance of switches and crossings compared with plain line is complicated by the presence of movable parts, changing rail geometry and non-uniformities in the composite and/or trackbed stiffness. These features lead to complex vehicle–track interactions and higher maintenance costs. The trackbed stiffness is the least well-controlled engineering property. A greater variability in trackbed stiffness leads to higher differential trackbed settlement and associated poorer track quality. At switches and crossings, changes in trackbed stiffness are exacerbated by changing rail properties which also contribute to changes in the overall composite track stiffness. This work focuses on the role of variations in stiffness on the performance of switches and crossings. Field measurements of bearer displacement were carried out using geophones at a switch and crossing equipped with under sleeper pads. The vehicle–switch and crossing interaction was modelled using a multi-body system and finite element method. The trackbed stiffness along the whole of the switch and crossing was inferred using the measurements of track deflections in an iterative back-calculation taking account of changing rail properties. It is shown that not including the variation in trackbed/composite stiffness leads to significant under/overestimates of the wheel–rail contact forces. Under sleeper pads are shown to reduce absolute maximum loads, but may increase the variation in deflection.

Match and Training Load Exposure and Time-Loss Incidence in Elite Rugby Union Players.

ObjectiveTo investigate the impact of match and training load on time-loss incidence in elite, professional Rugby Union players.Materials and MethodsEighty-nine Rugby Union players were monitored over two seasons of training and competition. Load was measured for all training sessions and matches using subjective [session ratings of perceived exertion (sRPE) load; RPE × session duration] and objective [global positioning systems (GPS); distance and high-speed running distance] methods and quantified using multiple approaches; absolute match and training load, acute:chronic workload ratio (ACWR), exponentially weighted moving average (EWMA) and cumulative 7, 14, 21, and 28 d sums. Mixed effect models were used to assess the effect of each variable on time-loss incidence.ResultsOf the 474 time-loss incidences that occurred across the two seasons, 50.0% were contact injuries (86.5% occurred during matches and 13.5% during training), 34.8% were non-contact injuries (31.5% occurred during matches and 68.5% during training) and 15.2% were cases of illness. The absolute match and training load variables provided the best explanation of the variance in time-loss incidence occurrence [sRPE load: p < 0.001, Akaike information criterion (AIC) = 2936; distance: p < 0.001, AIC = 3004; high-speed running distance: p < 0.001, AIC = 3025]. The EWMA approach (EWMA sRPE load: p < 0.001, AIC = 2980; EWMA distance: p < 0.001, AIC = 2980; EWMA high-speed running distance: p = 0.002, AIC = 2987) also explained more of the variance in time-loss incidence occurrence than the ACWR approach (ACWR sRPE load: p = 0.091, AIC = 2993; ACWR distance: p = 0.008, AIC = 2990; ACWR high-speed running distance: p = 0.153, AIC = 2994).ConclusionOverall, the absolute sRPE load variable best explained the variance in time-loss incidence, followed by absolute distance and absolute high-speed running distance. Whilst the model fit using the EWMA approach was not as good as the absolute load variables, it was better than when the same variables were calculated using the ACWR method. Overall, these findings suggest that the absolute match and training load variables provide the best predictors of time-loss incidence rates, with sRPE load likely to be the optimal variant of those examined here.

Mean Propulsive Velocity Is a Viable Method for Adjusting the Resistance-Training Load at Moderate Altitude.

We examined the viability of using mean propulsive velocity (MPV) to adjust the load in the countermovement jump (CMJ) at moderate altitude. Twenty-four volunteers were assigned to a 4-week power-oriented resistance training (RT) program in either normoxia (N, 690 m) or intermittent hypobaric hypoxia (IH, 2,320 m). The load was adjusted to maintain execution velocity of CMJ at 1m·s−1 of MPV. Relative peak power output (Prel), and percentage of velocity loss throughout the sets (VL) were determined for each session. The internal load was measured by the rating of perceived exertion (RPE). The absolute load lifted was higher in IH compared to N (75.6 ± 8.4 vs. 58.5 ± 12.3 kg P < 0.001). However, similar relative increases for both groups were found when comparing the final values (IH: 8.2%, P = 0.007; N: 9.8%, P = 0.03) with no changes in VL between groups (P = 0.36). Post-study Prel improved significantly only in IH (+7% W·kg−1, P = 0.002). Mean RPE was greater in IH vs. N (6.8 ± 1.5 vs. 5.6 ± 2, P < 0.001). The MPV seems to be a viable method for adjusting external load during RT at moderate altitude. However, given that RT at moderate altitude increases RPE, it is prudent to monitor internal load when using the MPV to best determine the actual physiological stress of the session.

Absolute and Relative Load and Injury in Elite Junior Australian Football Players Over 1 Season.

To investigate the association between training and match loads and injury in elite junior Australian football players over 1 competitive season. Elite junior Australian football players (n = 290, age 17.7 [0.3] y, range 16-18y) were recruited from the under-18 state league competition in Victoria to report load and injury information. One-week load (session rating of perceived exertion multiplied by duration) and all time-loss injuries were reported using an online sport-injury surveillance system. Absolute load measures (weekly sums) enabled the calculation of relative measures such as the acute:chronic workload ratio. Load measures were modeled against injury outcome (yes/no) using a generalized estimating equation approach, with a 1-wk lag for injury. Low (<300arbitrary units [au]) and high (>4650au) 1-wk loads were associated with significantly higher risk of injury. Furthermore, low (<100au) and high (>850au) session loads were associated with a higher risk of injury. High strain values (>13,000) were associated with up to a 5-fold increase in the odds of injury. There was a relatively flat-line association between the acute:chronic workload ratio and injury. This study is the first investigation of elite junior athletes demonstrating linear and nonlinear relationships between absolute and relative load measures and injury. Coaches should focus player loads on, or at least close to, the point at which injury risk starts to increase again (2214au for 1-wk load and 458au for session load) and use evidence-based strategies across the week and month to help reduce the risk of injury.

Acute Neuromuscular and Endocrine Responses to Two Different Compound Exercises: Squat vs. Deadlift.

Barnes, MJ, Miller, A, Reeve, D, and Stewart, RJ. Acute neuromuscular and endocrine responses to two different compound exercises: squat vs. deadlift. J Strength Cond Res 33(9): 2381-2387, 2019-Anecdotally, it is believed that the deadlift exercise brings about greater levels of central fatigue than other exercises; however, no empirical evidence exists to support this view. In addition, little is known about the acute endocrine response to heavy deadlift exercise and how this may differ from other similar compound exercises. Therefore, the aim of this study was to identify and compare the acute, neuromuscular and endocrine responses to squat and deadlift exercises. Ten resistance-trained males completed 8 sets of 2 repetitions at 95% of 1 repetition maximum. Maximum voluntary isometric contraction (MVIC) force of the quadriceps, along with measures of central (voluntary activation [VA] and surface electromyography) and peripheral (electrically evoked control stimulus) fatigue were made before and 5 and 30 minutes after exercise. In addition, salivary testosterone and cortisol were measured at these same time points. MVIC was reduced after the completion of both exercises (p = 0.007); however, no difference between exercises was evident. Similarly, although VA changed over time (p = 0.0001), no difference was observed between exercises. As a measure of peripheral fatigue, force from the control stimulus changed over time (p = 0.003) with a greater decrease evident after the squat (p = 0.034). Electromyography was reduced over time (p = 0.048) but no difference was seen between exercises. No change was seen in testosterone and cortisol. Although a greater absolute load and larger volume load were completed for the deadlift, no difference in central fatigue was evident between the 2 compound exercises. The greater peripheral fatigue observed after squat exercise may be due to the greater work completed by the quadriceps with this exercise. These results suggest that separate periodization, tapering, and programming considerations may be unnecessary when using the squat and deadlift to develop muscular strength.

Minimising energy consumption and environmental burden of freight transport using a novel graphical decision-making tool

This study introduces a new graphical decision-making tool to facilitate the rapid selection of transportation modes with minimum energy consumption or emissions, indicating the most sustainable transportation mode. Greenhouse gas (GHG) and air pollutants (NOx, PM and SO2), together with a composite price-weighted total environmental burden (TEB), are considered in the analysis. The graphical tool, which has a similar appearance to a phase diagram, presents a map of energy use (or emission) of different transportation modes based on the values of the ratio of the transportation distances (R) and the absolute load (L). A freight transportation case study (Rotterdam to Antwerp and Genova) demonstrates the construction and application of the graphical tool. For this case study, the electric train is the transport mode that offers the lowest energy consumption and minimum TEB. The graphical decision tool can also indicate the next-best solutions when one or more options (e.g. electric train) are not available. In this scenario, general cargo shipping achieves the lowest GHG emission, but heavy lorry imposes the lowest TEB. The developed tool further demonstrates the impacts of possible future fuels and technology developments on transportation selection, including renewable biodiesel and transport electrification under different grid mixes (e.g. Latvia, Sweden and EU-28). Further criteria, including economics, can be included for future study using the proposed tool as a foundation. The graphical approach transforms the transport selection problem into an easily understandable format from which arises sound solutions.

More than microbial relative abundances.

The concept of reference frames inspires researchers to develop a differential ranking system for measuring relative differential abundance, which does not require information about absolute microbial load.

Rating of perceived exertion and velocity loss as variables for controlling the level of effort in the bench press exercise

ABSTRACT There is a growing interest in the analysis of different methods for monitor fatigue during resistance training sessions. This study aimed to (1) analyse the relationships between the percentage of performed repetitions with respect to the maximum possible number (%REP), RPE and magnitude of velocity loss (VL), and (2) examine whether a multiple regression analysis with the RPE and VL as predictor variables could improve the goodness of fit to predict %REP in the bench press exercise performed in a Smith machine. Seven men performed a repetition maximum test, on 3 separate testing sessions, against 3 different absolute loads based on a target mean velocity (MV) according to an individual load-velocity profile (≈1.00, ≈0.70, and ≈0.50 m/s). MV, VL, %REP and RPE were collected and used for analysis. Based upon quadratic polynomial regression analysis strong relationships were reported between the RPE and %REP (r2 = 0.89 and SEE = 9.85%) and between the VL and %REP (r2 = 0.91 and SEE = 9.85%). Multiple regression analysis with the RPE and VL as predictor variables improved the goodness of fit (r 2 = 0.94 and SEE = 7.18%) of the model to predict %REP. These results suggest that both RPE and VL are useful variables to accurately estimate %REP in the bench press exercise.

Superoxide and NADPH oxidase do not modulate skin blood flow in older exercising adults with and without type 2 diabetes

ObjectiveHigh aerobic fitness may prevent age-related decrements in cutaneous vasodilation while type 2 diabetes may exacerbate this decline. The mechanisms underlying these responses remain unclear, but may be due to an excess of reactive oxygen species. We hypothesized that superoxide scavenging or NADPH oxidase inhibition would improve cutaneous vasodilation in older adults exercising in the heat, particularly in healthy low-fit individuals and those with type 2 diabetes. MethodsTwenty seven older adults were evenly separated into three groups (healthy low-fit: VO2peak = 24.4 ± 2.4 ml·kg−1·min−1, 61 ± 8 years; healthy high-fit: 42.5 ± 9.7 ml·kg−1·min−1, 56 ± 6 years; type 2 diabetes: 30.0 ± 7.6, ml·kg−1·min−1, 58 ± 7 years). The healthy low-fit and type 2 diabetes groups performed two successive 30-min cycling bouts at 65%VO2peak in the heat (35°C), separated by 30-min rest. The high-fit group cycled at the same absolute heat load (and therefore requirement for heat loss) as their healthy low-fit counterparts during the first exercise bout (Ex1) and at the same relative intensity (65%VO2peak) during the second (Ex2). Forearm cutaneous vascular conductance (CVC%max) was measured at microdialysis sites perfused with: 1) lactated Ringer's solution (control); 2) 10 mM NG-nitro-L-arginine-methyl-ester (L-NAME, nitric oxide synthase inhibitor); 3) 100 μM apocynin (NADPH oxidase inhibitor); 4) 10 μM tempol (superoxide dismutase mimetic), with responses compared at baseline, end-Ex1, and end-Ex2. ResultsIn all groups, L-NAME consistently reduced CVC%max relative to the other treatment sites by ~16–21% during Ex1 and by ~22–27% during Ex2 (all P < 0.05). Conversely, superoxide scavenging and NADPH oxidase inhibition did not influence CVC%max (all P > 0.05). ConclusionSuperoxide and NADPH oxidase do not modulate cutaneous vasodilation in healthy low- or high-fit older adults exercising in the heat, regardless of aerobic fitness level or relative exercise intensity employed, nor do they influence cutaneous vasodilation during an exercise-heat stress in those with type 2 diabetes. However, NOS remains an important modulator of cutaneous vasodilation during exercise in all groups.

An In Vitro Study to Determine the Effect of Ulnar Shortening on Distal Forearm Loading During Wrist and Forearm Motion: Implications in the Treatment of Ulnocarpal Impaction

To evaluate the effect of ulnar shortening on distal forearm loading following simulated dynamic motion. Ulnar shortening was simulated using a custom-built adjustable implant to simulate up to 4 mm of ulnar shortening (-4 mm) in 9 cadaveric extremities. Load cells were placed in the distal ulna and radius to quantify axial loading. Using a wrist and forearm motion simulator, absolute and percentage loads were measured during dynamic flexion, ulnar deviation(UD), flexion dart throw (DT), and pronation. There was a significant decrease in absolute and percentage distal ulnar loads at each interval of ulnar shortening during flexion, UD, DT, and pronation. The distal ulna bore no compressive loads, and in fact, tensile loads were measured in the ulna at 2 mm of ulnar shortening during DT and pronation, at 3 mm during flexion, and at 4 mm during UD. A progressive decrease in distal ulnar loads with generation of tensile loads was observed with sequential ulnar shortening. Ulnar shortening greater than 2 mm can result in tensile loading in the distal ulna. When managing ulnar impaction syndrome, excessive shortening may not be required to provide relief of symptoms.

Reliability of the Maximal Resisted Sprint Load Test and Relationships With Performance Measures and Anthropometric Profile in Female Field Sport Athletes.

Petrakos, G, Tynan, NC, Vallely-Farrell, AM, Kiely, C, Boudhar, A, and Egan, B. Reliability of the maximal resisted sprint load test and relationships with performance measures and anthropometric profile in female field sport athletes. J Strength Cond Res 33(6): 1704-1714, 2019-Resisted sled sprint (RSS) training is an effective modality for the improvement of linear sprint speed. Previous methods of RSS load prescription, e.g., an absolute load or as a percentage of body mass (%BM), do not account for interindividual differences in strength, power, or speed characteristics, although the "maximum resisted sled load" (MRSL) method of RSS load prescription may provide a solution. Maximum resisted sled load is defined as the final RSS load before an athlete can no longer accelerate between 2 phases (10-15 and 15-20 m) of a 20-m linear sprint. However, the MRSL test has not been analyzed for reliability. In addition, MRSL performance has not been compared with the outcome of other performance tests. The primary aim of this study was to investigate the reliability of the MRSL testing protocol in female field sport athletes. Participants (age, 20.8 ± 1.9 years; body mass, 64.3 ± 8.4 kg; height, 1.66 ± 0.65 m) tested for anthropometric measurements, strength and power performance testing, and twice for MRSL. Maximum resisted sled load values ranged from 20.7 to 58.9% BM. Maximum resisted sled load test-retest reliability intraclass correlation coefficient, confidence intervals, and coefficient of variations were 0.95, 0.85-0.98, and 7.6%, respectively. Maximum resisted sled load was"moderately" and "strongly" correlated with a number of anthropometric and performance tests (p ≤ 0.05), including percentage fat free mass, countermovement jump, loaded countermovement jump, rate of force development, horizontal jump, and horizontal bound performance. Maximum resisted sled load is a reliable measure for determining the RSS load at which an individual can no longer accelerate during a single RSS effort over 0-20 m. Maximum resisted sled load also accounts for interindividual variation in body composition, power, and speed characteristics of female field sport players.