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1.
ABSTRACT: Leary, BK, Statler, J, Hopkins, B, Fitzwater, R, Kesling, T, Lyon, J, Phillips, B, Bryner, RW, Cormie, P, and Haff, GG. The relationship between isometric force-time curve characteristics and club head speed in recreational golfers. J Strength Cond Res 26(10): 2685-2697, 2012-The primary purpose of the present investigation was to examine the relationships between club head speed, isometric midthigh pull performance, and vertical jump performance in a cohort of recreational golfers. Twelve recreational golfers (age, 20.4 ± 1.0 years; weight, 77.0 ± 9.8 kg; height, 177.8 ± 6.3 cm; body fat, 17.1 ± 7.6%; handicap, 14.5 ± 7.3; experience, 8.9 ± 3.6 years) completed 3 testing sessions: (a) familiarization session and body composition measurements; (b) measurement of force-time curves in the isometric midthigh pull, countermovement, and static vertical jump (SJ); and (c) measurement of club head speed. During sessions 1 and 2, subjects performed 5 countermovement jumps, 5 SJ, and 2 isometric midthigh pulls. Isometric peak force was measured at 30, 50, 90, 100, 200, and 250 milliseconds. Rate of force development was measured among 0-30, 0-50, 0-90, 0-100, 0-200, and 0-250 milliseconds. Peak rate of force development was determined as the highest value in a 10-millisecond sampling windows. During session 3, subjects performed 10 maximal golf swings with a driver to measure club head speed; peak and average club head speed were analyzed across the 10 swings. Golf handicap was moderately correlated with average (r = -0.52, p = 0.04) and maximal club head speed (r = -0.45, p = 0.07). Force at 150 milliseconds during the isomeric midthigh pull test was moderately correlated with average (r = 0.46, p = 0.07) and maximal club head speed (r = 0.47, p = 0.06). Moderate correlations were also found between the rate of force development from 0 to 150 milliseconds and average (r = 0.38, p = 0.11) and maximal club head speed (r = 0.36, p = 0.12). The present findings suggest that the ability to exhibit high ground reaction forces in time frames <200 milliseconds are related to high club head speeds.  相似文献   

2.
There is little information about the effects of caffeine intake on female team-sport performance. The aim of this study was to investigate the effectiveness of a caffeine-containing energy drink to improve physical performance in female soccer players during a simulated game. A double-blind, placebo controlled and randomized experimental design was used in this investigation. In two different sessions, 18 women soccer players ingested 3 mg of caffeine/kg in the form of an energy drink or an identical drink with no caffeine content (placebo). After 60 min, they performed a countermovement jump (CMJ) and a 7 × 30 m sprint test followed by a simulated soccer match (2 × 40 min). Individual running distance and speed were measured using GPS devices. In comparison to the placebo drink, the ingestion of the caffeinated energy drink increased the CMJ height (26.6 ± 4.0 vs 27.4 ± 3.8 cm; P < 0.05) and the average peak running speed during the sprint test (24.2 ± 1.6 vs 24.5 ± 1.7 km/h; P < 0.05). During the simulated match, the energy drink increased the total running distance (6,631 ± 1,618 vs 7,087 ± 1,501 m; P < 0.05), the number of sprints bouts (16 ± 9 vs 21 ± 13; P < 0.05) and the running distance covered at >18 km/h (161 ± 99 vs 216 ± 103 m; P < 0.05). The ingestion of the energy drink did not affect the prevalence of negative side effects after the game. An energy drink with a dose equivalent to 3 mg of caffeine/kg might be an effective ergogenic aid to improve physical performance in female soccer players.  相似文献   

3.
We used three techniques of precooling to test the hypothesis that heat strain would be alleviated, muscle temperature (Tmu) would be reduced, and as a result there would be delayed decrements in peak power output (PPO) during exercise in hot, humid conditions. Twelve male team-sport players completed four cycling intermittent sprint protocols (CISP). Each CISP consisted of twenty 2-min periods, each including 10 s of passive rest, 5 s of maximal sprint against a resistance of 7.5% body mass, and 105 s of active recovery. The CISP, preceded by 20 min of no cooling (Control), precooling via an ice vest (Vest), cold water immersion (Water), and ice packs covering the upper legs (Packs), was performed in hot, humid conditions (mean +/- SE; 33.7 +/- 0.3 degrees C, 51.6 +/- 2.2% relative humidity) in a randomized order. The rate of heat strain increase during the CISP was faster in Control than Water and Packs (P < 0.01), but it was similar to Vest. Packs and Water blunted the rise of Tmu until minute 16 and for the duration of the CISP (40 min), respectively (P < 0.01). Reductions in PPO occurred from minute 32 onward in Control, and an increase in PPO by approximately 4% due to Packs was observed (main effect; P < 0.05). The method of precooling determined the extent to which heat strain was reduced during intermittent sprint cycling, with leg precooling offering the greater ergogenic effect on PPO than either upper body or whole body cooling.  相似文献   

4.
This study aimed to determine if combined exercise intervention improves physical performance and gait joint-kinematics including the joint angle and dynamic range of motion (ROM) related to the risk of falling in community-dwelling elderly women. A 12-week combined exercise intervention program with extra emphasis on balance, muscle strength, and walking ability was designed to improve physical performance and gait. Twenty participants attended approximately two-hour exercise sessions twice weekly for 12 weeks. Participants underwent a physical performance battery, including static balance, sit and reach, whole body reaction time, 10 m obstacle walk, 10 m maximal walk, 30-second chair stand, to determine a physical performance score, and received quantitative gait kinematics measurements at baseline and in 12 weeks. Significant lower extremity strength improvement 13.5% (p<.001) was observed, which was accompanied by significant decreases in time of the 10 m obstacle walk (p<.05) and whole body reaction time (p<.001) in this study. However, no significant differences were seen for static balance and flexibility from baseline. For gait kinematics, in the mid-swing phase, knee and hip joint angle changed toward flexion (p<.01, p<.05, respectively). Ankle dynamic ROM significantly increased (p<.05) following exercise intervention. The plantar flexion angle of the ankle in the toe-off phase was increased significantly (p<.01). However, other gait parameters were not significantly different from baseline. These findings from the present investigation provide evidence of significant improvements in physical performance related to the risk factors of falling and safe gait strategy with a combined exercise intervention program in community-dwelling elderly women. The results suggest this exercise intervention could be an effective approach to ameliorate the risk factors for falls and to promote safer locomotion in elderly community-dwelling women.  相似文献   

5.
Sildenafil causes pulmonary vasodilation, thus potentially reducing impairments of hypoxia-induced pulmonary hypertension on exercise performance at altitude. The purpose of this study was to determine the effects of sildenafil during normoxic and hypoxic exercise. We hypothesized that 1) sildenafil would have no significant effects on normoxic exercise, and 2) sildenafil would improve cardiac output, arterial oxygen saturation (SaO2), and performance during hypoxic exercise. Ten trained men performed one practice and three experimental trials at sea level (SL) and simulated high altitude (HA) of 3,874 m. Each cycling test consisted of a set-work-rate portion (55% work capacity: 1 h SL, 30 min HA) followed immediately by a time trial (10 km SL, 6 km HA). Double-blinded capsules (placebo, 50, or 100 mg) were taken 1 h before exercise in a randomly counterbalanced order. For HA, subjects also began breathing hypoxic gas (12.8% oxygen) 1 h before exercise. At SL, sildenafil had no effects on any cardiovascular or performance measures. At HA, sildenafil increased stroke volume (measured by impedance cardiography), cardiac output, and SaO2 during set-work-rate exercise. Sildenafil lowered 6-km time-trial time by 15% (P<0.05). SaO2 was also higher during the time trial (P<0.05) in response to sildenafil, despite higher work rates. Post hoc analyses revealed two subject groups, sildenafil responders and nonresponders, who improved time-trial performance by 39% (P<0.05) and 1.0%, respectively. No dose-response effects were observed. During cycling exercise in acute hypoxia, sildenafil can greatly improve cardiovascular function, SaO2, and performance for certain individuals.  相似文献   

6.
Generation of reactive oxygen species (ROS) is a normal process in the life of aerobic organisms. Under physiological conditions, these deleterious species are mostly removed by the cellular antioxidant systems, which include antioxidant vitamins, protein and non-protein thiols, and antioxidant enzymes. Since the antioxidant reserve capacity in most tissues is rather marginal, strenuous physical exercise characterized by a remarkable increase in oxygen consumption with concomitant production of ROS presents a challenge to the antioxidant systems.An acute bout of exercise at sufficient intensity has been shown to stimulate activities of antioxidant enzymes. This could be considered as a defensive mechanism of the cell under oxidative stress. However, prolonged heavy exercise may cause a transient reduction of tissue vitamin E content and a change of glutathione redox status in various body tissues. Deficiency of antioxidant nutrients appears to hamper antioxidant systems and augment exercise-induced oxidative stress and tissue damage. Chronic exercise training seems to induce activities of antioxidant enzymes and perhaps stimulate GSH levels in body fluids. Recent research suggest that supplementation of certain antioxidant nutrients are necessary for physically active individuals.  相似文献   

7.
8.
Suction feeding mechanics, performance, and diversity in fishes   总被引:1,自引:0,他引:1  
Despite almost 50 years of research on the functional morphologyand biomechanics of suction feeding, no consensus has emergedon how to characterize suction-feeding performance, or its morphologicalbasis. We argue that this lack of unity in the literature isdue to an unusually indirect and complex linkage between themuscle contractions that power suction feeding, the skeletalmovements that underlie buccal expansion, the sharp drop inbuccal suction pressure that occurs during expansion, the flowof water that enters the mouth to eliminate the pressure gradient,and the forces that are ultimately exerted on the prey by thisflow. This complexity has led various researchers to focus individuallyon suction pressure, flow velocity, or the distance the preymoves as metrics of suction-feeding performance. We attemptto integrate a mechanistic view of the ability of fish to performthese components of suction feeding. We first discuss a modelthat successfully relates aspects of cranial morphology to thecapacity to generate suction pressure in the buccal cavity.This model is a particularly valuable tool for studying theevolution of the feeding mechanism. Second, we illustrate themultidimensional nature of suction-feeding performance in acomparison of bluegill, Lepomis macrochirus, and largemouthbass, Micropterus salmoides, two species that represent oppositeends of the spectrum of performance in suction feeding. As anticipated,bluegills had greater accuracy, lower peak flux into the mouth,and higher flow velocity and acceleration of flow than did bass.While the differences between species in accuracy of strikeand peak water flux were substantial, peak suction velocityand acceleration were only about 50% higher in bluegill, a relativelymodest difference. However, a hydrodynamic model of the forcesthat suction feeders exert on their prey shows that this differencein velocity is amplified by a positive effect of the smallermouth aperture of bluegill on force exerted on the prey. Ourmodel indicates that the pressure gradient in front of a fishthat is feeding by suction, associated with the gradient inwater velocity, results in a force on the prey that is largerthan drag or acceleration reaction. A smaller mouth apertureresults in a steeper pressure gradient that exerts a greaterforce on the prey, even when other features of the suction floware held constant. Our work shows that some aspects of suction-feedingperformance can be determined from morphology, but that thecomplexity of the behavior requires a diversity of perspectivesto be used in order to adequately characterize performance.  相似文献   

9.
This study was performed to determine the effects of an exercise physiology program on physical fitness, body satisfaction, and knowledge. A total of 161 students (mean age = 16.5 +/- 0.89 years) of the Coral Gables Senior High School served as the experimental group volunteers, whereas 33 students enrolled in a standard biology course served as the control group (mean age = 15.61 +/- 0.84 years). The experimental group received exercise physiology theory coupled with active aerobic and resistance exercise. Age (p = 0.0001) and lean body mass (p = 0.023) were the only physical characteristics significantly greater in the experimental group at pretesting. An analysis of covariance controlling for pretest values showed better results in the experimental compared with the control group for sit and reach (p = 0.008), step test, recovery heart rate (p = 0.0002), overhead press (p = 0.002), bench press (p = 0.017), leg press (p = 0.012), sit-ups (p = 0.001), body satisfaction (p = 0.0009), and physiology knowledge (p = 0.0001) at posttesting. Findings indicated that a biology curriculum integrated with exercise physiology theory and exercise activities may result in significant improvements in physical fitness, body size satisfaction, and physiology knowledge in high school adolescents.  相似文献   

10.
The effect of oral caffeine ingestion on intense intermittent exercise performance and muscle interstitial ion concentrations was examined. The study consists of two studies (S1 and S2). In S1, 12 subjects completed the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test with prior caffeine (6 mg/kg body wt; CAF) or placebo (PLA) intake. In S2, 6 subjects performed one low-intensity (20 W) and three intense (50 W) 3-min (separated by 5 min) one-legged knee-extension exercise bouts with (CAF) and without (CON) prior caffeine supplementation for determination of muscle interstitial K(+) and Na(+) with microdialysis. In S1 Yo-Yo IR2 performance was 16% better (P < 0.05) in CAF compared with PLA. In CAF, plasma K(+) at the end of the Yo-Yo IR2 test was 5.2 ± 0.1 mmol/l with no difference between the trials. Plasma free fatty acids (FFA) were higher (P < 0.05) in CAF than PLA at rest and remained higher (P < 0.05) during exercise. Peak blood glucose (8.0 ± 0.6 vs. 6.2 ± 0.4 mmol/l) and plasma NH(3) (137.2 ± 10.8 vs. 113.4 ± 13.3 μmol/l) were also higher (P < 0.05) in CAF compared with PLA. In S2 interstitial K(+) was 5.5 ± 0.3, 5.7 ± 0.3, 5.8 ± 0.5, and 5.5 ± 0.3 mmol/l at the end of the 20-W and three 50-W periods, respectively, in CAF, which were lower (P < 0.001) than in CON (7.0 ± 0.6, 7.5 ± 0.7, 7.5 ± 0.4, and 7.0 ± 0.6 mmol/l, respectively). No differences in interstitial Na(+) were observed between CAF and CON. In conclusion, caffeine intake enhances fatigue resistance and reduces muscle interstitial K(+) during intense intermittent exercise.  相似文献   

11.
Postexercise carbohydrate-protein (CHO + PRO) supplementation has been proposed to improve recovery and subsequent endurance performance compared to CHO supplementation. This study compared the effects of a CHO + PRO supplement in the form of chocolate milk (CM), isocaloric CHO, and placebo (PLA) on recovery and subsequent exercise performance. Ten cyclists performed 3 trials, cycling 1.5 hours at 70% VO?max plus 10 minutes of intervals. They ingested supplements immediately postexercise and 2 hours into a 4-hour recovery. Biopsies were performed at recovery minutes 0, 45, and 240 (R0, R45, REnd). Postrecovery, subjects performed a 40-km time trial (TT). The TT time was faster in CM than in CHO and in PLA (79.43 ± 2.11 vs. 85.74 ± 3.44 and 86.92 ± 3.28 minutes, p ≤ 0.05). Muscle glycogen resynthesis was higher in CM and in CHO than in PLA (23.58 and 30.58 vs. 7.05 μmol·g?1 wet weight, p ≤ 0.05). The mammalian target of rapamycin phosphorylation was greater at R45 in CM than in CHO or in PLA (174.4 ± 36.3 vs. 131.3 ± 28.1 and 73.7 ± 7.8% standard, p ≤ 0.05) and at REnd in CM than in PLA (94.5 ± 9.9 vs. 69.1 ± 3.8%, p ≤ 0.05). rpS6 phosphorylation was greater in CM than in PLA at R45 (41.0 ± 8.3 vs. 15.3 ± 2.9%, p ≤ 0.05) and REnd (16.8 ± 2.8 vs. 8.4 ± 1.9%, p ≤ 0.05). FOXO3A phosphorylation was greater at R45 in CM and in CHO than in PLA (84.7 ± 6.7 and 85.4 ± 4.7 vs. 69.2 ± 5.5%, p ≤ 0.05). These results indicate that postexercise CM supplementation can improve subsequent exercise performance and provide a greater intracellular signaling stimulus for PRO synthesis compared to CHO and placebo.  相似文献   

12.
The purpose of this study was the investigation of the effects of an intensive combined training program based on the pretest scores of a university women's basketball team on their physical, physiological, biomotoric, and technical features. Twenty-four university volunteers were equally divided into two groups: an experiment group (intensive combined training group) and a control (technical training) group. The 10-week intensive combined training program was performed on the experiment group according to their pretest outcomes. Before and at the end of each period of training, which was scheduled four times a week, the physical, physiological, biomotoric, and technical performance of each subject were determined. With respect to the pre- and posttest measurements, the basketball group showed significant differences (p < 0.05) in girth measurements (shoulder, waist, hip, arm, thigh, and calf), in skinfold measurements (percent body fat), in physiological measurements (vital capacity and forced vital capacity), in biomotoric tests (right-left hand grip, dynamic and countermovement jump, sit-up, push-up, 1500-m endurance), and in technique tests (free and inside shooting). It can be concluded that a 10-week intensive combined training program performed on university women basketball players had a significant effect on improving their physical, physiological, biomotoric, and technical features. It proved to be highly recommendable for female basketball players who are preparing for short-term tournaments; the basketball group in this study won a championship.  相似文献   

13.
Vitamin E, physical exercise and tissue damage in animals   总被引:2,自引:0,他引:2  
L Packer 《Medical biology》1984,62(2):105-109
  相似文献   

14.
The induction of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), a key regulator of mitochondriogenesis, is well-established under multiple physical exercise regimens, including, endurance, resistance, and sprint training. We wanted to determine if increased expression of PGC-1alpha in muscle is sufficient to improve performance during exercise in vivo. We demonstrate that muscle-specific expression of PGC-1alpha improves the performance during voluntary as well as forced exercise challenges. Additionally, PGC-1alpha transgenic mice exhibit an enhanced performance during a peak oxygen uptake exercise test, demonstrating an increased peak oxidative capacity, or whole body oxygen uptake. This increased ability to perform in multiple exercise paradigms is supported by enhanced mitochondrial function as suggested by increased mitochondrial gene expression, mitochondrial DNA, and mitochondrial enzyme activity. Thus this study demonstrates that upregulation of PGC-1alpha in muscle in vivo is sufficient to greatly improve exercise performance under various exercise paradigms as well as increase peak oxygen uptake.  相似文献   

15.
Growth hormone (GH) treatment reverses the muscle loss allegedly responsible for diminished aerobic capacity and increased fatigue in patients with HIV-associated wasting. This study examined whether submaximal measures of physical performance can be used as objective measures of the functional impact of GH treatment-induced anabolism. We randomized 27 HIV-positive men [mean (SD) age, 43.9 (7.2) yr; body mass, 71.9 (10.4) kg; BMI, 23.1 (2.8) kg/m2] with unintentional weight loss despite antiretroviral therapy to receive GH (6 mg) or placebo in a double-blinded, placebo-controlled, cross-over trial with a 3-mo washout. Lean body mass (LBM), maximum oxygen uptake (Vo2 peak), ventilatory threshold (VeT), 6-min walk test (6MWT) distance and work, profile of mood states (POMS) fatigue and vigor scores, and Nottingham health profile (NHP) energy and physical mobility scores were measured. LBM significantly increased after 3 mo of GH treatment vs. placebo (means +/- SE, 3.7 +/- 0.6 vs. 0.3 +/- 0.4 kg; P < 0.001). VeT significantly improved (17.6 +/- 3.7 vs. -5.9 +/- 2.5%; P < 0.001), but Vo2 peak did not change significantly. 6MWT distance improved (24.9 +/- 9.7 vs. 19.9 +/- 11.6 m; P > 0.05) and 6MWT work increased significantly more after 3 mo of GH treatment (33.3 +/- 8.8 vs. 16.5 +/- 7.5 kJ; P < 0.05). POMS scores of fatigue and vigor and the NHP score of energy improved, yet the changes were not statistically significant. GH treatment improved VeT linearly to the increase in LBM (r =0.43, P = 0.037) and 6MWT work (r = 0.51, P = 0.008), and the increase in 6MWT work correlated with increase in LBM (r = 0.45, P = 0.024). Improvement in 6MWT work above the median (27.3 kJ) showed a decrease in fatigue (r = -0.62, P = 0.024). We concluded that GH treatment-induced LBM gains in HIV-associated wasting were functionally relevant, as determined by effort-independent submaximal measures of cardiopulmonary exercise testing.  相似文献   

16.
2-months restriction of physical activity of dogs markedly reduced their capacity for prolonged running. The rate of exercise-induced Tre increases was significantly higher in the cage-confined dogs in comparison with controls. At the point of exhaustion blood glucose concentration and muscle glycogen content were similar in the control and cage-confined animals, in spite of the much shorter time of exercise until exhaustion in the latter. The exercise-induced increases in plasma FFA concentration were considerably lower in dogs after prolonged inactivity period in spite of the greater activation of the adrenergic system. It is concluded, that there are several factors which may contribute to the reduction of the ability of cage-confined dogs to perform prolonged physical exercise. The most important seems to be the diminished muscle glycogen content, modifications in exercise metabolism and exercise-induced hyperthermia.  相似文献   

17.
This study examined the effects of a typical fencing training program on selected hormones, neuromuscular performance, and anthropometric parameters in peripubertal boys. Two sets of measurements, before training and after 12 months of training, were performed on 2 groups of 11- to 13-year-old boys. One group consisted of fencers (n = 8), who trained regularly for the 12-month period, and the other group (n = 8) consisted of inactive children of the same age. There was no difference in Tanner's maturation stage of the 2 groups before (controls, 2.5 +/- 0.3; fencers, 2.1 +/- 0.3) and after the 12 months (controls, 3.0 +/- 0.3; fencers, 3.0 +/- 0.3). Serum testosterone, growth hormone, sex hormone binding globulin, free androgen index, and leptin changed significantly over time, reaching similar values in the 2 groups at the end of the study. Significantly greater increases in body mass (16 +/- 3%) and leg cross-sectional area (CSA) (32 +/- 7%) were observed only in the fencers' group, and these differences disappeared when height was set as a changing covariate. Although there was a greater increase in height for the fencers compared to the control group (8.6 +/- 1.2 vs. 3.6 +/- 0.9 cm, p < 0.01), the height reached at the end of the study was almost identical in the 2 groups (controls, 163.6 +/- 5.1; fencers, 165.4 +/- 2.8). Arm CSA, handgrip strength, and vertical jump performance changed significantly over time for both groups, with no differences between groups. It was concluded that a typical fencing training program for peripubertal boys did not have any effect on selected growth and anabolic hormones and did not influence the normal growth process, as this was reflected by changes in selected anthropometric and neuromuscular performance parameters. This may be because of the characteristics of the present fencing training program, which may not be adequate to alter children's hormonal functions in such a way as to override the rapid changes occurring during puberty.  相似文献   

18.
19.
In order to examine the effect of acute respiratory acidosis induced by CO2 inhalation prior to maximal exercise on blood lactate and physical performance, double determinations were carried out for each subject on separate days; one day, after CO2 inhalation and other day, after inhalation of room air. It was observed that in the untrained subjects the CO2 inhalation prior to maximal treadmill exercise does not affect endurance time and maximum aerobic power, whereas blood lactate during recovery was lower in CO2 breathing than that in room air. In addition, no significant difference of 200m sprint time in the athletes was noticed between CO2 and room air while blood lactate after 200m sprint running was significantly lower in the CO2 than that in room air. From these results, it was suggested that the effect of CO2 inhalation prior to maximal exercise as applied here appeared to be mediate through metabolic rather than oxygen transport mechanism, but not related to physical performance.  相似文献   

20.
The purpose of this study was to investigate the changes in the body composition, body size, muscle strength, and VO2max after 24 weeks of resistance or endurance training and detraining in young men. Thirty healthy college-aged men (20.4 ± 1.36 years) participated in the study. Subjects were assigned to resistance training group (RTG, n = 10), endurance training group (ETG, n = 10), and control group (CG, n = 10). The training program consisted of running or weight-resistance exercise for 3 sessions per week under supervision. VO2max, upper and lower body strength (UBS, LBS), body fat, lean body mass, and body circumference were measured at baseline and after training and detraining. After the training period, the exercise groups demonstrated significant increases in VO2max and LBS (p < 0.05). The UBS, lean mass (LM), and body size of arm and calf were significantly greater in the RTG than in the other 2 groups (p<0.05). In addition, the strength and LM of the RTG were still greater than the baseline values after 24 weeks of detraining (p < 0.05). The conclusions of this study are (a) that endurance or resistance training alone led to training-specific improvements in physical performance, body composition, and body size of the arms for the young men examined and (b) that the RTG maintained the gains in strength and LM for more prolonged periods after training ceased than the endurance training group.  相似文献   

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