Application of the eigenstrain approach to predict the residual stress distribution in laser shock peened AA7050-T7451 samples

Laser Shock Peening allows the introduction of deep compressive residual stresses into metalliccomponents. It is applicable to most metal alloys used for aerospace applications. The method is relativelyexpensive in application, and therefore development studies often rely heavily on Finite Element Modellingto simulate the entire process, with a high computational cost. A different approach has been used recently,the so-called eigenstrain approach. The present study looks at the feasibility of applying the eigenstrainmethod for prediction of the residual stress in a sample that contains curved surface features. Theeigenstrain is determined from a simple geometry sample, and applied to the more complex geometry topredict the residual stress after Laser Shock Peening. In particular the prediction of residual stress at acurved edge, and for different values of material thickness, have been studied. The research hasdemonstrated that the eigenstrain approach gives promising results in predicting residual stresses whenboth the thickness and the geometry of the peened surface is altered

On-Sight and Red-Point Climbing : Changes in Performance and Route-Finding Ability in Male Advanced Climbers

Aim: In lead climbing, the ascent of the route can be defined as on-sight or red-point. On-sight is the more challenging style since it demands greater physiological and psychological commitment. The differences between the two modes in advanced climbers have not been studied much. Two essential skills needed to optimize performance, in both on-sight and in red-point climbing, are route interpretation (RI) ability and movements sequence recall. Therefore, this study aimed to compare performance between on-sight and red-point ascent in advanced climbers and evaluate how a climber\u2019s RI ability and movement sequences recall might change before and after on-sight and red-point climbing. Methods: Eighteen advanced male climbers (age 29.2 \ub1 4.7 years, body mass 67.8 \ub1 3.6 kg, stature 175.2 \ub1 2.4 cm, best red-point and on-sight grades 7b+/8a and 7a+/7b+, respectively) were video-recorded during the route ascent in on-sight and red-point modes to evaluate performance and to measure static and dynamic action times. RI ability and movement sequence recall were assessed before and after each climb. Level of anxiety was evaluated via a self-report questionnaire. Heart rate (fH), lactate concentration, ([La\u2013]), and rating of perceived exertion (RPE) were detected during and after each climb. Results: Compared to on-sight, an improvement in performance was observed in a red-point climb: the ascent was faster (148.7 \ub1 13.6 s and 179.5 \ub1 12.5 s, respectively, P < 0.05), smoother (significant reduction in exploratory moves and in stops times, P < 0.05), less demanding physiologically (lower fHpeak and [La\u2013]peak, P < 0.05), and psychologically (lower RPE, cognitive and somatic anxiety and higher self-confidence, P < 0.05). The RI ability was improved in red-point versus on-sight and, in the same mode, between pre and post ascent. Conclusion: Red-point climbing was found to be less demanding than on-sight, both physiologically and psychologically, under the conditions investigated by this study. Our findings suggest that RI is a trainable skill and underscore the importance of including specific techniques in training programs designed to improve interaction between perceptual, psychological, and physiological factors

The Performance Effect of Scheduled Carbohydrate and Caffeine Intake during Simulated Team Sport Match-Play

The aim of the current investigation was to identify the effects of scheduled carbohydrate (CHO) and caffeine (CAF) supplementation on simulated team sport match-play performance. Ten male hurling players completed three hurling match-play simulation protocols (HSP) performed 7 days apart in a double-blind, randomized design. Supplementation included CHO, CHO + CAF, and placebo (PLA). In a randomized order, participants ingested either a 6% CHO solution, a PLA solution of similar taste, or a combined intake of 6% CHO solution + 200 mg CAF capsule. At specific time points (Pre-0 min; half time (HT)-30 min; full time (FT)-60 min), participants completed a repeated sprint protocol (RAST; 12 7 20 m). Physiological [% maximal oxygen uptake (%VO2max), % mean oxygen uptake (%VO2mean), % maximal heart rate (%HRmax), % mean heart rate (%HRmean), respiratory exchange ratio (RER), and blood lactate (BLa)] and performance [(best sprint time (RSAbest), mean sprint time (RSAmean), and rate of perceived exertion (RPE)] variables were monitored throughout each simulation. Non-significant differences were observed between supplement trials (CHO, CHO + CAF, and PLA) for BLa (\u3b72 = 0.001, small), %VO2max (\u3b72 = 0.001, small), %VO2mean (\u3b72 = 0.004, small), %HRmax (\u3b72 = 0.007, small), %HRmean (\u3b72 = 0.018, small), RER (\u3b72 = 0.007, small), RPE (\u3b72 = 0.007, small), and RSAbest (\u3b72 = 0.050, small). RSAmean performance significantly improved in CHO + CAF trials compared to PLA, with sprint times significantly improved from Pre to FT also (\u3b72 = 0.135, medium). A significant difference was observed in BLa between time points (Pre, HT, and FT) (\u3b72 = 0.884, large) in % HRmax (\u3b72 = 0.202, medium), %HRmean (\u3b72 = 0.477, large), and RER (\u3b72 = 0.554, large) across halves and in RPE across time points (\u3b72 = 0.670, large). Our data provide novel data regarding the effects of CHO and CAF supplementation on team sport performance, with co-ingestion of CHO + CAF reducing the decrement in repeated sprint performance compared to PLA

Evidence of balance training‐induced improvement in soccer‐specific skills in U11 soccer players

The present study aim was to determine the role of balance training in improving technical soccer skills in young players. Two U11 soccer teams were randomly assigned one to either balance training (BT; n=22) or control group (Ctrl; n=21). At the end of their habitual soccer training (identical in BT and Ctrl), BT underwent additional balance training for 12 weeks (3sessions/week, 20 min per session), while Ctrl had a 20\u2010min scrimmage. Before and after the intervention, BT and Ctrl underwent two soccer\u2010specific tests (Loughborough Soccer Passing, LSPT, and Shooting, LSST, Tests), and bipedal and unipedal balance evaluations. After intervention, both groups decreased the trials time and improved passing accuracy, with larger improvements in BT than Ctrl [LSPT penalty time (CI95%): \u20102.20 s (\u20102.72/\u20101.68); ES (CI95%): \u20102.54 s (\u20103.34/\u20101.74)]. Both groups improved balance ability, with BT showing larger increments in bipedal tests than Ctrl [static balance: \u201029 mm (\u201042/\u201016); ES: \u20101.39 (\u20102.05/\u20100.72); limit of stability: 4% (3/5); ES 3.93 (2.90/4.95); unipedal quasi\u2010dynamic balance: 0.07 a.u. (0.03/0.11); ES: 1.04 (0.40/1.67) and active range of motion: \u20105% (\u20108/\u20102); ES \u20100.89 (\u20101.51/\u20100.26)]. Low\u2010to\u2010moderate correlations between the players\u2019 technical level and unipedal balance ability were retrieved, particularly in the non\u2010dominant limb (R from 0.30 to 0.48). Balance training improved some technical soccer skills more than habitual soccer training alone, suggesting that young soccer players may benefit from additional balance training added to their traditional training

Specific adaptations in performance and muscle architecture after weighted jump-squat vs body mass squat jump training in recreational soccer players

The aim of the present study was to compare the effects of weighted jump squat (WJST) vs body mass squat jump training (BMSJT) on quadriceps muscle architecture, lower-limb lean-mass (LM) and muscle strength, performance in change of direction (COD), sprint and jump in recreational soccer-players. Forty-eight healthy soccer-players participated in an off-season randomized controlled-trial. Before and after an eight-week training intervention, vastus lateralis pennation angle, fascicle length, muscle thickness, LM, squat 1-RM, quadriceps and hamstrings isokinetic peak-torque, agility T-test, 10 and 30m sprint and squat-jump (SJ) were measured. Although similar increases in muscle thickness, fascicle length increased more in WJST (ES=1.18, 0.82-1.54) than in BMSJT (ES=0.54, 0.40-0.68) and pennation angle only increased in BMSJT (ES=1.03, 0.78-1.29). Greater increases in LM were observed in WJST (ES=0.44, 0.29-0.59) than in BMSJT (ES=0.21, 0.07-0.37). Agility T-test (ES=2.95, 2.72-3.18), 10m (ES=0.52, 0.22-0.82) and 30m-sprint (ES=0.52, 0.23-0.81) improved only in WJST, while SJ improved in BMSJT (ES=0.89, 0.43-1.35) more than in WJST (ES=0.30, 0.03-0.58). Similar increases in squat 1-RM and peak-torque occurred in both groups. The greater inertia accumulated within the landing-phase in WJST vs BMSJT has increased the eccentric workload, leading to specific eccentric-like adaptations in muscle architecture. The selective improvements in COD in WJST may be related to the increased braking ability generated by the enhanced eccentric workload

Greater fatigability in knee-flexors vs. knee-extensors after a standardized fatiguing protoco

The present study aimed to investigate the effects of a standardized fatiguing protocol on central and peripheral fatigue in knee-flexors and knee-extensors. Thirteen healthy men (age: 23\u2009\ub1\u20093 years; height: 1.78\u2009\ub1\u20090.09 m; body-mass: 73.6\u2009\ub1\u20099.2\u2005kg) volunteered for the present study. Maximal voluntary contraction (MVC), Electromyography (EMG) activity, voluntary activation level (VAL) as an index of central fatigue and twitch potentiation as an index of peripheral fatigue were measured before and after the fatiguing protocol. The fatiguing protocol consisted of a 0.6 duty-cycle to exhaustion (6\u2005s isometric contraction, 4\u2005s recovery) at 70% MVC. After the fatiguing protocol, MVC decreased in both (Effect-size (ES)\u2009=\u20091.14) and knee-extensors (ES\u2009=\u20091.14), and EMG activity increased in both knee-flexors (ES\u2009=\u20092.33) and knee-extensors (ES\u2009=\u20091.54). Decreases in VAL occurred in knee-flexors (ES\u2009=\u20090.92) but not in knee-extensors (ES\u2009=\u20090.04). Decreases in potentiation occurred in both knee-flexors (ES\u2009=\u20090.84) and knee-extensors (ES\u2009=\u20090.58). The greater central occurrence of fatigue in knee-flexors than in knee-extensors may depend on the different muscle morphology and coupled with a greater tolerance to fatigue in knee-extensors. The present data add further insight to the complicated knee-flexors-to-knee-extensors strength relationship and the mechanisms behind the different occurrence of fatigue

The match-play sprint performance of elite senior hurlers during competitive games

The typical sprint profile in elite hurling has yet to be established. The purpose of this study was to investigate the sprinting demands of elite hurling competition and characterize the sprinting patterns of different playing positions. GPS (10-Hz, STATSports Viper) were used to collect data from 51 hurlers during 18 games. The total sprint ( 6522 km\ub7h-1) distance (TSD), the number of sprints (NOS) classified as length (<20 m, 6520 m) and relative speed thresholds (<80%, 80-90%, >90%), the between-sprint duration and the number of repeated-sprint bouts ( 652 sprints in 6460 s) were analyzed. The NOS was 22.2 \ub1 6.8 accumulating 415 \ub1 140 m TSD. The NOS <20 m, 6520 m was 14.0 \ub1 4.7 and 8.1 \ub1 3.6 respectively. The NOS <80%, 80-90% and >90% was 10.6 \ub1 4.3, 8.2 \ub1 3.6, 3.4 \ub1 2.4 respectively. The between-sprint duration and the repeated-sprint bouts were 208 \ub1 86 s and 4.5 \ub1 2.6 respectively. TSD (ES = -0.20), NOS (ES = -0.34), NOS <20 m (ES = -0.33), 6520 m (ES = -0.24), 80-90% (ES = -0.35) >90% (ES = -0.13) and repeated-sprint bouts (ES = -0.28) decreased between-halves. Full-backs performed a lower NOS <80% than half-backs (ES = -0.66) and a shorter mean duration of sprints than half-backs (ES = -0.75), midfielders (ES = -1.00) and full-forwards (ES = -0.59). These findings provide a sprint profile of elite hurling match-play that coaches should consider to replicate the sprint demands of competition in training

Cardiorespiratory responses to cycle exercise during a low-intensity sinusoidal work rate

Purpose: Sinusoidal varying protocols have been recently re-proposed in assessing the cardiorespiratory response (CRR) to exercise to reflect the variability in long-lasting physical activities. Contrary to square-wave tests, the cyclic nature of sinusoidal work rate allows to explore the CRR kinetics several times. Previous studies used to overlap CRR of successive periods; however, so far no study assessed whether CRRs are constant along different cycles. Therefore, this study aimed at investigating the CRR during an exhausting low-intensity sinusoidal work rate. Methods: Seven subjects (age: 27 ± 7 yr, body mass: 72.5 ± 6.7 kg; stature: 1.8 ± 0.1 m) participated to the study. After determining on different days the maximum oxygen uptake (V’O2max) by ramp cycle ergometric test and critical power (CP) via different submaximal exercises, they underwent a sinusoidal work rate until exhaustion. The exercise varied according to a sinewave function with a midpoint (MP) equal to 50 W below CP (CP-50), an amplitude (A) of 50 W and a period of 4 min. Expiratory ventilation (V’E), carbon dioxide output (V’CO2), oxygen uptake (V’O2) and heart rate (HR) were obtained breath-by-breath and fitted off-line by the sinewave functions that minimized the residuals. Thereafter, A, MP and the timedelay (tD, the latency between mechanical and CRR signals) were obtained for each cycle. A one-way ANOVA for repeated measures was applied to test the effect of fatigue. Results: MP of V’E, V’O2 and HR significantly increased as well as A of V’E and V’CO2 (p\0.05 for all parameters). On the contrary, A of HR decreased during the test (p\0.05). No changes were detected on tD in all CRRs parameters. Conclusions: This study demonstrates that despite the low intensity level of the sinusoidal protocol, the dynamics of CRRs are not constant. Therefore, averaging the CRRs of different cycles might introduce a bias in the outcomes concealing a marked change in CRRs. References 1. Fukuoka Y et al. (2002) Dynamics of the heart rate response to sinusoidal work in humans: influence of physical activity and age. Clinical Science 102: 31–38 2. Miyamoto Y et al. (1983) Cardiorespiratory Dynamics during Sinusoidal and Impulse Exercise in Man. The Japanese Journal of Physiology 33: 971-98

Evidence of Improved Vascular Function in the Arteries of Trained but Not Untrained Limbs After Isolated Knee-Extension Training

Vascular endothelial function is a strong marker of cardiovascular health and it refers to the ability of the body to maintain the homeostasis of vascular tone. The endothelial cells react to mechanical and chemical stimuli modulating the smooth muscle cells relaxation. The extent of the induced vasodilation depends on the magnitude of the stimulus. During exercise, the peripheral circulation is mostly controlled by the endothelial cells response that increases the peripheral blood flow in body districts involved but also not involved with exercise. However, whether vascular adaptations occur also in the brachial artery as a result of isolated leg extension muscles (KE) training is still an open question. Repetitive changes in blood flow occurring during exercise may act as vascular training for vessels supplying the active muscle bed as well as for the vessels of body districts not directly involved with exercise. This study sought to evaluate whether small muscle mass (KE) training would induce improvements in endothelial function not only in the vasculature of the lower limb (measured at the femoral artery level in the limb directly involved with training), but also in the upper limb (measured at the brachial artery level in the limb not directly involved with training) as an effect of repetitive increments in the peripheral blood flow during training sessions. Ten young healthy participants (five females, and five males; age: 23 \ub1 3 years; stature: 1.70 \ub1 0.11 m; body mass: 66 \ub1 11 kg; BMI: 23 \ub1 1 kg \ub7 m 122 ) underwent an 8-week KE training study. Maximum work rate (MWR), vascular function and peripheral blood flow were assessed pre- and post-KE training by KE ergometer, flow mediated dilatation (FMD) in the brachial artery (non-trained limb), and by passive limb movement (PLM) in femoral artery (trained limb), respectively. After 8 weeks of KE training, MWR and PLM increased by 44% (p = 0.015) and 153% (p = 0.003), respectively. Despite acute increase in brachial artery blood flow during exercise occurred (+25%; p < 0.001), endothelial function did not change after training. Eight weeks of KE training improved endothelial cells response only in the lower limb (measured at the femoral artery level) directly involved with training, likely without affecting the endothelial response of the upper limb (measured at the brachial artery level) not involved with training