Prehospital fibrinolysis with timely coronary angiography resulted in effective reperfusion in patients with early STEMI who could not undergo primary PCI within 1 hour after the first medical contact. However, fibrinolysis was associated with a slightly increased risk of intracranial bleeding. (Funded by Boehringer Ingelheim; ClinicalTrials.gov number, NCT00623623.).
The effects of oral creatine supplementation on muscle phosphocreatine (PCr) concentration, muscle strength, and body composition were investigated in young female volunteers (n = 19) during 10 wk of resistance training (3 h/wk). Compared with placebo, 4 days of high-dose creatine intake (20 g/day) increased (P < 0.05) muscle PCr concentration by 6%. Thereafter, this increase was maintained during 10 wk of training associated with low-dose creatine intake (5 g/day). Compared with placebo, maximal strength of the muscle groups trained, maximal intermittent exercise capacity of the arm flexors, and fat-free mass were increased 20-25, 10-25, and 60% more (P < 0. 05), respectively, during creatine supplementation. Muscle PCr and strength, intermittent exercise capacity, and fat-free mass subsequently remained at a higher level in the creatine group than in the placebo group during 10 wk of detraining while low-dose creatine was continued. Finally, on cessation of creatine intake, muscle PCr in the creatine group returned to normal within 4 wk. It is concluded that long-term creatine supplementation enhances the progress of muscle strength during resistance training in sedentary females.
This study aimed to compare the effects of oral creatine (Cr) supplementation with creatine supplementation in combination with caffeine (Cr+C) on muscle phosphocreatine (PCr) level and performance in healthy male volunteers (n = 9). Before and after 6 days of placebo, Cr (0.5 g x kg-1 x day-1), or Cr (0.5 g x kg-1 x day-1) + C (5 mg x kg-1 x day-1) supplementation, 31P-nuclear magnetic resonance spectroscopy of the gastrocnemius muscle and a maximal intermittent exercise fatigue test of the knee extensors on an isokinetic dynamometer were performed. The exercise consisted of three consecutive maximal isometric contractions and three interval series of 90, 80, and 50 maximal voluntary contractions performed with a rest interval of 2 min between the series. Muscle ATP concentration remained constant over the three experimental conditions. Cr and Cr+C increased (P < 0.05) muscle PCr concentration by 4-6%. Dynamic torque production, however, was increased by 10-23% (P < 0.05) by Cr but was not changed by Cr+C. Torque improvement during Cr was most prominent immediately after the 2-min rest between the exercise bouts. The data show that Cr supplementation elevates muscle PCr concentration and markedly improves performance during intense intermittent exercise. This ergogenic effect, however, is completely eliminated by caffeine intake.
Creatine loading raises muscle PCr concentration and improves performance during rapid and dynamic intermittent muscle contractions. Creatine loading does not facilitate muscle PCr resynthesis during intermittent isometric muscle contractions.
U ntil 2015, consensus statements 1,2 advised against sports participation more vigorous than golf for patients with implantable cardioverter-defibrillators (ICDs) because of the postulated risks of death caused by failure to defibrillate, injury resulting from arrhythmia-related syncope or shock, or device damage. The multinational, prospective, observational ICD Sports Safety Registry quantified risks associated with sports participation for athletes receiving ICDs on the basis of standard criteria. Initial results (2013 3 ) demonstrated no death, failure to defibrillate, or injury resulting from arrhythmia or shock during sports. On the basis of these data, the 2015 eligibility and disqualification recommendations for competitive athletes with cardiovascular disease 4 now state that competitive sports may be considered for athletes with ICDs. This report describes 4-year follow-up of the completed registry. Methods are as reported previously.3 The Yale University Human Investigation Committee approved the study. All participants gave written informed consent.Among 440 participants, 393 in organized sports and 47 in high-risk sports, the most common diagnoses were long-QT syndrome (n=87, 20%), hypertrophic cardiomyopathy (n=75, 17%), and arrhythmogenic right ventricular cardiomyopathy (n=55, 13%). Of 201 subjects with a preimplantation history of ventricular fibrillation (VF) or tachycardia (VT), 61 (30%) had VT/VF during sports. At enrollment, median time since implantation was 26 months (interquartile range, 11-59 months), with 126 subjects (29%) enrolled within 1 year of implantation. The most common organized sports were running, basketball, and soccer; the most common dangerous sport was skiing. Seventy-seven subjects (18%) engaged in varsity/junior varsity/ traveling team competition, (highly competitive subgroup). Seventy-two postcollege athletes (16%) participated at a national/international level.Median follow-up was 44 months (interquartile range, 30-48 months), totaling 1446 person-years. Thirty-seven participants did not complete the study: 20 were lost to follow-up (all confirmed alive), 5 withdrew, 6 developed worsening cardiac/ medical conditions, 4 had the ICD removed, and 2 died (neither death was sports related, as reported previously 3 ). There were no tachyarrhythmic deaths or externally resuscitated tachyarrhythmias during or after sports participation or injury resulting from arrhythmia-related syncope or shock during sports. The 95% confidence interval for the occurrence of adverse event based on 376 participants followed up at least 2 years was 0% to 0.9% and based on 167 participants followed up at least 4 years was 0% to 2.2%.The numbers and rhythms of shocks received for the overall group and the highly competitive subgroup are shown in the Table. Forty-six (10%) received appropriate shocks (for VT/VF) during competition or practice, a rate of 3 per 100 person-years (identical to the initial report 3 ). More participants received shocks during competition/ practice or physical a...
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