Meningococcal disease outbreak related to the World Scout Jamboree in Japan, 2015

Problem: Six invasive meningococcal disease cases occurred among Scottish and Swedish nationals associated with the World Scout Jamboree (WSJ), an international mass gathering, held in Japan. The index case developed symptoms while returning home. The strains from all six cases were identical and seldom seen in Japan. Context: Over 33 000 participants from 155 countries attended WSJ. At the Jamboree site, participants of the North of Scotland’s and Sweden’s units camped within the same subcamp and kept the same schedule of events. No information was available about the Swedish and Scottish cases’ close personal contact history. Action: Health Protection Scotland investigated Scottish cases, conducted active case finding, provided chemoprophylaxis, vaccinated close contacts and advised Scottish WSJ participants and contacts to seek medical care if they developed symptoms. The Public Health Agency of Sweden recommended chemoprophylaxis to all participants in Sweden. In Japan, the Ministry of Health, Labour and Welfare (MHLW) requested the Scout Association of Japan advise all participants to seek medical attention if they developed symptoms. MHLW shared information about the event with local authorities, medical associations, and the Ministry of Education, Culture, Sports, Science and Technology. Outcome: No additional case related to WSJ has been reported. This outbreak highlighted the risk for international spread of invasive meningococcal disease at international mass gatherings. Discussion: Assessing risk, educating participants, enhancing surveillance and sharing timely information among related countries are significant for prevention and response against invasive meningococcal disease outbreaks at mass gatherings.

Effects of resistance training on CO2 excess and swimming performance in competitive swimmers / 体力科学

The purpose of the present study was to determine the change in total excess volume of CO<SUB>2</SUB>output (CO<SUB>2</SUB>excess) due to bicarbonate buffering of lactic acid produced during exercise and change in swimming performance following resistance training for 8 weeks in competitive swimmers. Ten healthy university competitive swimmers were assigned to either a resistance training and swimming training group (COMBINE: N=5) or a swimming training only group (SWIM: N=5) . Muscle mass was measured using magnetic resonance imaging (MRI) . CO<SUB>2</SUB>excess and blood lactate concentration were measured during incremental exercise on a cycle ergometer and swimming performance was measured during competition. COMBINE showed a significantly higher percentage change in muscle mass (11.1±4.5%) than SWIM (3.5±2.5%) . The percentage change in CO<SUB>2</SUB>excess, CO<SUB>2</SUB>excess per body weight (CO<SUB>2</SUB>excess/BW) and CO<SUB>2</SUB>excess/BW per blood lactate accumulation (CO<SUB>2</SUB>excess/BW/ΔLa) during exercise was significantly higher in COMBINE (107.3±60.1, 102.6±56.8, 59.1±37.7%, respectively) than in SWIM (42.5±10.0, 42.9±10.4, 13.4±22.4%, respectively) . The percentage change in swimming performance was significantly higher in COMBINE (2.2±1.8%) than in SWIM (-2.0±3.6%) . A negative correlation between percentage change of muscle mass and percentage change of CO<SUB>2</SUB>excess/BW/ ΔLa (SWIM: r=-0.993, <I>P</I><0.01, COMBINE: r=-0.744, <I>P</I>>0.05) was found. It was suggested that combined swim and resistance training resulted in greater increases in the bicarbonate buffering system (CO<SUB>2</SUB>excess/BW/ΔLa) . However, increases in muscle mass may have subsequently caused a relative decrease in the contribution of the bicarbonate buffering system.

The effect of strength training in muscle and nerve is memorized and reinforced by retraining / 体力科学

The purpose of this study was to prove the hypothesis that the effect of strength training is memorized and reinforced by retraining. Untrained university-age men participated in this training program. The retraining leg was subjected to 5 weeks of isometric training, 17 weeks of detraining and 5 weeks of retraining in knee extension. The contralateral training leg was subjected to 5 weeks of isometric training during the same period as the retraining phase of the retraining leg. Maximal isometric torque of knee extension increased after the 5-week training and remained at the trained level during the 17week detraining period. Torque gain by retraining of the retraining leg was 2.6 times greater than that of the contralateral training leg. These changes in isometric torque corres-ponded with changes in iEMG of the vastus lateralis. The cross-sectional area of the quadriceps femoris muscle did not change with training. Results support the hypothesis that the effect of strength training is memorized and reinforced by retraining. In addition, results show that these adaptations would be explained by recruitment and rate coding of motor units.

The difference between effects of "power-up type" and "bulk-up type" strength training exercises. With special reference to muscle cross-sectional area, muscular strength, anaerobic power and anaerobic endurance / 体力科学

In this study, the difference between the effects of “power-up type” and “bulk-up type” strength training exercise was investigated by analyzing parameters such as structural and functional adaptations in the neuromuscular system. Eleven subjects were divided into power-up and bulk-up groups. The power-up group comprised five male subjects who performed 5 sets at 90% of one repetition maximum (1 RM) with a 3-min rest between sets (repetition method) . The bulk-up group comprised six male subjects who performed 9sets at 80-60-50%, 70-50-40%, and 60-50-40% of 1 RM with rest intervals between sets of either 30 s or 3 min (interval method) . Both groups performed isotonic knee extension exercise twice a week for 8 weeks. The power-up group showed a lower rate of improvement than the bulk-up group in terms of cross-sectional area (CSA) of the quadriceps femoris at levels 30%, 50% and 70% from the top of the femur, and also in average isokinetic strength (Isok. ave. ; 180 deg/s, 50 consecutive repetitions) . However, the power-up group showed a greater rate of improvement in 1 RM, maximal isometric strength (Isom. max), and maximal isokinetic strength (Isok. max ; 60, 180, 300 deg/s) . Furthermore, the rate of reduction in strength over 50 consecutive isokinetic repetitions decreased in the bulk-up group. On the other hand, the power-up group showed no significant changes in the above throughout the entire training program. These results indicate that the characteristics of the two types of training exercise are as follows : (1) power-up exercise is effective mainly for improving muscular strength and anaerobic power, and (2) bulk-up exercise is effective mainly for improving hypertrophy and anaerobic endurance. These findings support the idea that “power-up type” and “bulk-up type” strength training exercises should be applied appropriately according to the training aim.