Metabolic and lactate responses to supramaximal exercise in elite junior soccer players and distance runners

Aim: Elite soccer players are considered not as excellent but as good endurance athletes. Because of the characteristics of the game which is faster and is played at higher intensity, a high anaerobic power is also required characteristic of elite soccer players. Hence, the purpose of the present study was to compare the metabolic and lactate responses to 30s maximal cycle ergometer tests in high school soccer players and distance runners. Methods: Ten elite high school male soccer players (SP) and ten elite high school male distance runners (DR) volunteered as subjects in this study. Anaerobic power measures were obtained using Wingate anaerobic test including peak power (PP) and mean power (MP). The oxygen uptake (VO_2) was recorded breath-by-breath during the test (30s) and during the first 30s of recovery. Blood samples for lactate concentrations were drawn at rest before the test and during the 30-min recovery period. Results: Values (±SEM) of PP were 647 (±27) and 568 (±24) W in the SP and DR, respectively being significant (P<0.05). During the test, the DR had a significantly greater VO_2 than the SP (P<0.01). Blood lactate concentrations, on the other hand in recovery after the test were higher in the SP than DR. Conclusion: Those results would indicate that the energy supply for the 30s supramaximal exercise depended on the competitive specialty. The energy supply of the SP was more provided by the anaerobic metabolism and in the DR by the aerobic system

Thermal stress during table tennis bouts under high ambient temperature with and without fluid replacement

近年, 卓球は健康づくりや生涯スポーツの両面から実践者が増加している。高温多湿な本邦の夏季における長時間の卓球運動時の身体に対する暑熱ストレスはかなり大きいものと思われる。他方, 各種スポーツにおけるスポーツ飲料の活用は目覚しい。そこで本研究では高温多湿の環境下における長時間卓球練習時の生体に加わる暑熱ストレス軽減に対する水分補給効果について検討を試みた。The present study compared thermoregulatory and cardiovascular stresses during prolonged, simulated intermittent table tennis bouts (8×10-min bouts with 3-min rest intervals) at high ambient temperatures (30℃, 70%RH) with (F_I) and without (F_0). Four college table tennis players played against a table tennis robot that delivered 60 balls per min in the 2 environmental conditions. The performance task was to return the ball to a specific table target area on the table. During rest periods during F_I the subjects drank a commercial sport drink ad libitum. Pre- and post-trial measurements of body weight demonstrated a similar loss of sweat during F_0 and F_I after correcting the latter for fluid replacement. Rectal temperature (T_) arrd heart rate (HR) were significantly higher (P) followed similar patterns and no differences were observed between F_0 and F_I. This might be associated with similar rate of sweating during table tennis bouts in both trials. The intake of the carbohydrate-electrolyte fluid during F_I did not significantly affect plasma lactate. Thus the fluid intake during prolonged intermittent table tennis bouts was effective in reducing heat stress on thermoregulatory and cardiovascular functions

The effects of habitual cigarette smoking on maximal work capacity and pulmonary function

To evaluate the effects of cigarette smoking on some of the cardiorespiratory responses to maximal work as well as on pulmonary functions, a group of male adult subjects, 5 smokers and 5 nonsmokers, was studied. Work consisted of a bicycle ergometer test. For the determination of lung functions, Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV_) were tested. FEV_%, the ratio of FEV_ to FVC was also calculated. A resting carboxyhemoglobin (HbCO) level in the smoking group was significantly (P and FE V_% in nonsmokers than those in smokers were significant. These findings suggest that habitual cigarette smoking lowers maximal work performance as well as pulmonary function

Blood lactate and ventilatory responses to interval-and endurance-training in recreational runners

The purpose of the present study was to compare threshold levels of blood lactate and ventilation after two different training programs of 9 weeks, that is, interval-run (IR) and endurance-run (ER). Twenty (20) recreational male runners from local running clubs volunteered to this study and completed maximal ramp cycle tests to determine maximal aerobic power (VO_2max) and blood lactate concentrations. Maximal cycle testing involved progressing in increments of 25 watts (W) every 2 minutes following a 4-min warm-up period at 0 W. The subjects were requested to maintain a pedaling frequency of 60 rpm. The test was continued till the subjects reached a point of exhaustion. After baseline tests, subjects were matched in terms of the VO_2max and placed in one of two training groups, an interval-run group (IR, mean age 40 years), and an endurance-run group (ER, mean age 41.7 years). Gas analysis was carried out every 20 sec for minute ventilation, oxygen consumption, carbon dioxide production using Metamax system. Calculation of ventilatory threshold (VT) employed the V-slope method. Blood samples were collected during exercise from the brachial vein for analyses of blood lactate using YSI 1500 Sport Lactate analyzer. The value of blood lactate concentrations corresponding to 4 mmol/L for determining the lactate threshold (LT) was chosen. After training, there were significant increases in VO_2max, the estimated LT-4 mmol/L, and VT in both groups. In addition, faster running performance of 10 km after a 9-week training program was observed in the IR and ER groups with no significant differences between the groups. However, the magnitude of the aforementioned improvements was greater in the IR than ER groups. Blood lactate concentrations in both groups lowered significantly at all given work rates after 100 W during the incremental graded exercise. However, the lactate concentrations at higher work rates were significantly lower in the IR than ER groups. It was concluded that both aerobic interval-training and endurance-training produce increases in performance and physiological parameters. However, it seemed that, for runners who are already trained, notable improvements in endurance performance can be achieved only through high-intensity interval training

Plasma β-endorphin and lactate to marathon running in male fun runners : a positive aspect responding to endurance exercise

The concentration of beta-endorphin (B-EP) was measured in 12 male recreational runners before and after marathon running. All subjects could finish 42 km distance and their mean time for finishing was 3 hr and 50 min (3 hr 6 min - 4 hr 22 min). Plasma B-EP significantly (P<0.0001) increased to about 9.8-fold above base line, from 9.1 ± 0.8 (SE) to 88.9±17.0 pg/ml. In addition, B-EP remained above baseline at 30 min and 60 min after the marathon race (43.9 + 12.7 pg/ml; P<0.0001 and 33.6± 6.6 pg/ml; P<0.001, respectively) and dropped to baseline 24 hr following the race. Lactate concentration also significantly (P<0.0001) increased during the marathon race (from 11.8±0.12 to 2.33± 0.18 mmol/L). This value was far below anaerobic threshold levels, 4 mmol/L, and was equivalent to approximately 60-65% VO_2max of our subjects. Previous studies have reported that the peripheral B-EP responses may be intensity dependent and that an exercise intensity of at least 70% VO_2max for 15 min is needed to increase plasma B-EP. Since our subjects performed extremely over-duration exercise and were exhausted after the race, therefore, the undue physical stress might affect the increase in B-EP. In conclusion, plasma B-EP responses may be both intensity and duration dependent

EFFECTS OF EXTENDED-TERM EXERCISE ON THERMOREGULATION IN FEMALES

本研究は暑熱ストレスに対する体温調節応答についての男女差, および, 長期間にわたって高度に鍛練された女子スポーツ選手の応答について検索した。合計27名の大学生被検者〔運動鍛練女子 (FA) 11名, 非鍛練女子 (FNA) 8名, 非鍛練男子 (MNA) 8名〕が本実験に参加した。ここでいう運動鍛練者とは, 過去5ケ年以上, 持久的なスポーツ種目に参加しているスポーツ選手であり, 非鍛練者とは, 規則的に身体トレーニングの場に加わっていない者をいう。暑熱ストレスの条件は, 被検者が椅座安静位で, 温度42℃の水槽中に両脚を浸し (水面が膝の高さまでくるように調節する), 室温32℃ (湿度40%) に2時間暴露されるものであった。深部体温として舌下温 (Tor) を用い, 発汗開始の閾値体温を測定するために, 前腕部にヨード澱粉を塗布してその反応を用いた。総発汗量は, 暑熱暴露前後の体重 (ヌード) 減量から求め, 発汗速度は大原カプセル法を用いて測定した (胸部と背部)。 Torは時間の経過とともに上昇するが, 両非鍛練群間に差はなかった。しかしFAのTorは, 暴露30分ですでに他の2群より有意に低くなった。 発汗量の最っとも大きいのはMNAで, つぎにFA, もっとも小さいのがFNAであった。 また暴露時の心拍数の変動では, 両非鍛練群の値がほぼ同じで, FAの心拍数は有意に低くなった。FAの発汗閾値体温はFNA, MNAより0.4℃低くかった (P<0.01)。つぎに発汗速度を縦軸に, Torを横軸にとって, 単位Torあたりの発汗速度 (SR) をプロットして得たSR/Tor関係直線では, MNAがFAおよびFNAよりも有意に急峻となり, FAとFNA間には有意差が認められなかった。 しかし, FAの関係直線は, FNAより左方向 (低体温) にシフトされた格好を呈した。 鍛練者の発汗閾値体温が非鍛練者より低くなったのは, 暑熱ストレスに対する中枢性の温度適応と考えられ, このことが, 暴露中の体温上昇を他の2群よりも有意に低くおさえるのに働いたものと思われる。 そして, このような温度適応は, 四季を通じて, 激しい身体運動による熱産生 (冬季でも, 体温が39℃に上昇することもある) からくる暑熱ストレスへの適応結果であろう。非鍛練の男女群の深部体温に有意差が見られないのに, 男子群の発汗量が女子群より有意に多いのは, 女子の方が効果的な発汗をしていると考えてもよい。 ところが, 女子鍛練群の発汗量は, 非鍛練の女子群より多くなっているために, この問題はさらに検討されねばならない。 SR/Torの関係直線の勾配を比較すると, FAとFNAには差が現われないが, 男子の直線は女性鍛練者よりも有意に急峻である。 発汗開始温度が同一とすれば, SR/Tor関係直線の勾配の急峻の方が, 単位深部体温あたりの発汗量が大きいことを意味するものである。このことは, 男子の汗腺の分布が女子よりも多く, また個々の汗腺の発汗能力が男子において大きい, という生得的な要因にもとづくものと思われる。本研究の結果, 長期間にわたって高度に鍛練された女子スポーツ選手は, 暑熟ストレスに対して, (1)低い深部体温, (2)低い発汗開始閾値温, (3)相対的に単位深部体温あたりの大きな発汗量, (4)循環系に対する小さな負担度, などの応答を示し, 鍛練されない男子よりもすぐれた体温調節機構を備えているといえよう。Thermoregulatory responses to heat have been evaluated at rest in 27 university students : 11 female competitive athletes, 8 male non-athletes, and 8 female non-athletes. They rested for 2hrs at ambient temperature of 32℃, 40rh with legs immersed up to knees in a stirred water bath of 42℃. Total sweat volume of the female athletes was higher than the female non-athletes, but lower than the male non-athletes. Core temperature threshold for sweating was significantly lower in the female athletes than in the male and female non-athletes. The slope in sweat rate/core temperature relationship of the female athletes was not distinctly steeper than that of the female non-athletes. The thermoregulatory responses observed in the female athletes are thought to be comparable to those produced by heat adaptation. Comparing the heat responses in male and female non-athletes, no distinct sexual differences were observed in the rise in core temperature, mean skin temperature and the core temperature threshold for sweating. On the other hand, the slope in sweat rate/core temperature relationship was steeper in males than in females. The beneficial modifications of heat responses demonstrated in the present study in female athletes are similar to those observed in male athletes

平均台の前転とびにおける審判判定能力に対する一考察

There is a performance called a handspring forward in compulsory exercises on the balance beam. In the 8th Acquisition Test for an International Judge, it was reported that only 10 precent of the judges recognized that there was an air phase in the handspring forward. However, 90 percent of the remaining judges recognized the handspring forward as the walkover forward in the Barcelona Olympic Games. The handspring forward is used in the Olympics and also in other major championships from 1994 to 1996. This study was carried out to investigate whether a player\u27s performance has the air phase or not. Furthermore, this study investigated whether a judge can judge the air phase accurately or not. Many important things were found in the results. It is really hard to judge during a performance because the handspring forward has speed, and the air phase seems to appear in the handspring forward. To judge accurately whether there is an air phase or not, the judges have to watch repeatedly many performances that have air phases by using video tapes and investigate them. Also, it is very important and necessary that the judges have an ability to distinguish between the air phase and the walkover forward in the performance

Prevention of esophageal strictures after endoscopic submucosal dissection

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have recently been accepted as less invasive methods for treating patients with early esophageal cancers such as squamous cell carcinoma and dysplasia of Barrett\u27s esophagus. However, the large defects in the esophageal mucosa often cause severe esophageal strictures, which dramatically reduce the patient\u27s quality of life. Although preventive endoscopic balloon dilatation can reduce dysphagia and the frequency of dilatation, other approaches are necessary to prevent esophageal strictures after ESD. This review describes several strategies for preventing esophageal strictures after ESD, with a particular focus on anti-inflammatory and tissue engineering approaches. The local injection of triamcinolone acetonide and other systemic steroid therapies are frequently used to prevent esophageal strictures after ESD. Tissue engineering approaches for preventing esophageal strictures have recently been applied in basic research studies. Scaffolds with temporary stents have been applied in five cases, and this technique has been shown to be safe and is anticipated to prevent esophageal strictures. Fabricated autologous oral mucosal epithelial cell sheets to cover the defective mucosa similarly to how commercially available skin products fabricated from epidermal cells are used for skin defects or in cases of intractable ulcers. Fabricated autologous oralmucosal- epithelial cell sheets have already been shown to be safe