<title>Abstract</title><sec>
<title>Purpose</title>
This study aimed to investigate the medical care provided at the venue of the weightlifting event of the Tokyo 2020 Olympic Games.


</sec><sec>
<title>Methods</title>
We retrospectively evaluated athletes who availed of medical services at the venue during the weightlifting event of the Tokyo 2020 Olympic Games. In total, 194 athletes participated in the weightlifting competition.


Injuries and illnesses were classified into cases handled without physician or cases requiring medical examination by a physician. These were tabulated for each examination location (athlete medical station, field of play [FOP], first-aid station of training floor or warm-up area).


</sec><sec>
<title>Results</title>
Throughout the event, a cumulative total of 132 people used the venue medical services. Nine athletes required medical attention at the athlete medical stations. Of these nine cases, six occurred on the training floor. In the FOP, nine athletes were examined. Two experienced light-headedness, two had knee pain, and the rest had other symptoms. No athletes wanted to undergo medical examination at the athlete medical station. 89 medical procedures were performed in the first-aid station on the training floor, including 52 tapings and 37 ice compressions, and the most frequent body part which needed treatment was the knee, followed by the fingers. At the first-aid station on the match floor, 25 medical procedures were performed, including 17 ice compressions, 5 haemostasis, and 4 tapings. The body parts that most frequently needed treatment were the fingers, knees, and lower legs.


</sec><sec>
<title>Conclusion</title>
Several athletes needed treatment; however, only a few required medical care from a physician.


</sec>

The aim of this study was to investigate whether accommodating elastic bands with barbell back squats (BSQ) increase muscular force during the deceleration subphase. Ten healthy men (mean ± standard deviation: Age: 23 ± 2 years; height: 170.5 ± 3.7 cm; mass: 66.7 ± 5.4 kg; and BSQ one repetition maximum (RM): 105 ± 23.1 kg; BSQ 1RM/body mass: 1.6 ± 0.3) were recruited for this study. The subjects performed band-resisted parallel BSQ (accommodating elastic bands each sides of barbell) with five band conditions in random order. The duration of the deceleration subphase, mean mechanical power, and the force and velocity during the acceleration and deceleration subphases were calculated. BSQ with elastic bands elicited greater mechanical power output, velocity, and force during the deceleration subphase, in contrast to that elicited with traditional free weight (p < 0.05). BSQ with elastic bands also elicited greater mechanical power output and velocity during the acceleration subphase. However, the force output during the acceleration subphase using an elastic band was lesser than that using a traditional free weight (p < 0.05). This study suggests that BSQ with elastic band elicit greater power output during the acceleration and deceleration subphases.

Knee alignment is suggested to be a factor affecting each quadriceps femoris muscle size, and knee alignment such as Q-angle differs between men and women. Also, training can induce inhomogeneous hypertrophy among the quadriceps femoris, thereby leading to different component characteristics of the muscles. If Q-angle is a major determinant of the quadriceps femoris muscularity, it is hypothesized that the sex-related difference in the quadriceps femoris muscularity, if any, is further highlighted in trained individuals, being associated with Q-angle. We tested this hypothesis. Magnetic resonance images of the right thigh were obtained from 26 varsity rowers as trained subjects (13 for each sex) and 34 untrained individuals as controls (17 for each sex). From the images, muscle volume of each constituent of the quadriceps femoris (vastus lateralis, VL; medialis, VM; intermedius; rectus femoris) was determined. The Q-angle was measured during quiet bilateral standing with hand support as needed. Percent volume of VM to the total quadriceps femoris was greater in female rowers than male rowers and female controls, and that of VL was greater in male rowers than male controls. There were no correlations between Q-angle and percent muscle volume in any muscles regardless of rowing experience or sex. The current study revealed that well-trained rowers have sex-related quadriceps femoris muscularity but no significant correlations between percent muscle volume in any muscles and Q-angle. Our findings suggest that Q-angle is not a major determinant of the quadriceps femoris muscularity in either well-trained or untrained individuals.

The aim of this study was to investigate the effects of 8 weeks of training on O2 dynamics in university rugby players. University rugby players (n = 15) participated in 5 strength training sessions and 4 field-based training sessions per week for 8 weeks. Before and after 8-weeks’ training, the subjects performed ramp cycling exercise until exhaustion. Muscle O2 saturation (SmO2), relative changes from rest in deoxygenated hemoglobin concentration (∆Deoxy-Hb) and total hemoglobin concentration, cardiac output (CO), and pulmonary O2 uptake (VO2) were monitored continuously during exercise. Peak VO2 and CO were normalized by fat-free mass. Though peak VO2 tended to be increased after training, there were no significant changes in CO, nor any muscle O2 dynamic variables at peak exercise between before and after training. However, an increase in peak VO2 was significantly correlated with diminishment of deoxy-Hb and an increase in SmO2. Changes in CO caused by training were not related to improved peak VO2. The improvement of peak VO2 during 8 weeks of rugby training may have been caused by muscle O2 supply, rather than increased CO or muscle O2 extraction.

This study aimed to investigate the in vivo kinematics of shear modulus of the lower leg muscles in patients with medial tibial stress syndrome (MTSS). The study population included 46 limbs with MTSS and 40 healthy limbs. The shear modulus of the medial head of the gastrocnemius, lateral head of the gastrocnemius, soleus, peroneus longus and tibialis anterior muscles were measured using shear wave ultrasound elastography. As a result, the shear modulus of the lower leg muscles was significantly greater in patients with MTSS than in healthy patients (p &lt; 0.01). Based on the differences in shear modulus of lower leg muscles between the patients with MTSS and healthy patients, the measurements obtained via shear wave ultrasound elastography could be used to evaluate risk factors of MTSS. (E-mail: kei.akiyama@jpnsport.go.jp) (C) 2016 World Federation for Ultrasound in Medicine & Biology.

This study examined the relationship of muscle size indices of the pectoralis major muscle with bench press and bench throw performances in 18 male collegiate athletes. The maximal cross-sectional area (MCSA(MAx)) and volume (MV) of the pectoralis major muscle were determined by magnetic resonance imaging. First, subjects were tested for their one repetition maximum bench press strength (1RM(BP)) using a Smith machine. At a later date, subjects performed bench throws using the Smith machine with several different loads ranging from 30.0 kg to 90% of 1RM(BP). Barbell positions were measured by a linear position transducer, and bench throw power was calculated using a dynamic equation. Three trials were performed for each load. In all the trials, the maximal peak power was adopted as bench throw peak power (PPBT). The 1RM(BP) was significantly correlated with MCSA(MAx). Similarly, the correlation coefficient between MV and PPBT was significant. In contrast to the y-intercept of the MV-PPBT regression line, that of the MCSAM(Ax)-1RM(BP) regression line was not significantly different from 0. These results suggested that, although the dependence on pectoralis major muscle size is slightly different between bench press strength and bench throw power, the pectoralis major muscle size has a significant impact on bench press and throw performances. Greater muscle size leads to heavier body weight, which can be a negative factor in some sports. We therefore recommend that athletes and their coaches develop training programs for improving sports performance by balancing the advantage of increased muscle size and the potential disadvantage of increased body weight.

HIRAYAMA, K., T. YANAI, H. KANEHISA, T. FUKUNAGA, and Y. KAWAKAMI. Neural Modulation of Muscle-Tendon Control Strategy after a Single Practice Session. Med. Sci. Sports Exerc., Vol. 44, No. 8, pp. 1512-1518, 2012. Purpose: The purpose of the present study was to examine a hypothesis that the musculotendinous behavior during a propelling action with a countermovement can be altered by a single practice session through modulation of neuromuscular activities. Methods: Eight males performed unilateral maximal plantarflexion with (CMJ) and without (noCMJ) countermovement before and after a practice consisting of six sets of three repetitions of unilateral CMJ exercises. Measurements included EMG activities of the triceps surae and tibialis anterior muscles and the fascicle behavior of the gastrocnemius by ultrasonography, and impulse was calculated from the force-time data. The change in tendon length was also estimated. Results: The impulse in CMJ increased after the practice, but that in noCMJ did not. After the practice, the magnitude of fascicle lengthening and shortening in CMJ decreased, which was accompanied by an increase in tendon shortening without change in the ankle joint range of motion. The time lag from the onset of reaction force to that of EMG activities of the triceps surae muscles was shortened after the practice. Conclusions: The results support the hypothesis and indicate that, as a neural modulation through a single practice, the muscle-tendon unit behavior during CMJ can be optimized to improve the performance.

The purpose of the present study was to examine the influence of tendon elasticity, muscle strength and muscle activities on the amount of mechanical work enhancement associated with a counter movement. Twenty-one athletes performed a unilateral maximal jump using only the ankle joint with (CMJ) and without (no-CMJ) a counter movement on a sledge apparatus. Mechanical work done by the ankle joint was calculated from the ground reaction force and ankle joint kinematic parameters, and the difference between CMJ and no-CMJ conditions (ΔWork) was determined. During the exercise, electromyographic (EMG) activities were recorded from the triceps surae muscles. The maximal isometric plantar flexion torque and Achilles tendon stiffness were also determined using a torque meter and ultrasonogram. No significant correlation was found between ΔWork and either tendon stiffness or the maximal torque. In addition, neither the difference between CMJ and no-CMJ in iEMG nor mEMG was correlated with ΔWork. On the other hand, ΔWork was significantly correlated with the integrated EMG during the braking phase (r=0.52, p<0.05) and both the integrated (r=0.55, p<0.01) and mean (r=0.53, p<0.05) EMG during the push-off phase of CMJ. These results suggest that individual differences in ΔWork are influenced not by differences in the mechanical properties of the muscle-tendon unit, but by the individuality of muscle activities during CMJ.

体幹の深層に位置する腹横筋は、その解剖学的特性などから、脊柱のアライメントコントロールに寄与すると考えられている。我々は、これまでに腹横筋が特に活動すると思われるエクササイズを特定しており、そのエクササイズを用いて連続ホッピングのパフォーマンスがいかに変化するか検討した。その結果、予想に反してパフォーマンスに変化はみられなかった。現在は、その原因について検討している段階であり、結果がまとまり次第、発表を行う予定である。

反動動作を伴う運動（例：ドロップジャンプ）を用いたプライオメトリックトレーニングが、筋力トレーニングよりも反動動作を伴う運動のパフォーマンスを向上させることが報告されている。この理由として、「身体は課せられた刺激に対して特異的に適応する」という特異性の原理が挙げられているが、その具体的メカニズムは明らかにされていない。本研究では、プライオメトリックトレーニングがドロップジャンプパフォーマンスを向上させるメカニズムについて、筋腱動態および筋腱の機能特性に着目して検討した。その結果、筋腱動態と筋腱の機能特性の両方が変化することでジャンプパフォーマンスが向上していることが明らかとなった。

　反動を伴わない運動に比べ、反動を伴う運動ではより高い運動パフォーマンス（例：ジャンプ高）が発揮されること（反動効果）が広く知られている。反動効果のメカニズムは複数あり、運動様式や運動強度などによって貢献度が異なることが報告されている。これまでに、地面に接した状態から抜重することで比較的低い強度の反動をつけておこなうジャンプについては、筋活動のタイミングが変化し腱のバネ作用がより強調されることでジャンプパフォーマンスが改善されることが明らかにされている。一方、ある高さから落下し、その勢いを反動にする強度の高い反動運動においては、練習効果のメカニズムが異なる可能性がある。そこで本研究では、ドロップジャンプを対象に、1セッションの練習効果のメカニズムを神経筋活動等の観点から明らかにすることを目的とした。　被験者に十分なウォーミングアップを行わせた後、最大等尺性底屈トルク発揮および足関節のみを用いたドロップジャンプを行わせ、床反力の力積、足関節角度、下腿各筋の神経筋活動を定量した（事前測定）。同様の測定を15分の安静を挟んでもう一度行った後（中間測定）、ドロップジャンプを10回×3セット練習させ、引き続き事前測定と同様の測定（事後測定）を行った。　一部の被験者のデータに欠損が生じたため、統計処理を行うまでに至っていないが、ジャンプパフォーマンスの指標とした力積は概ね増加していた。このとき、最大等尺性底屈トルクには変化がなかったことから、力積の増加はウォームアップ等の効果ではなく、練習効果によるものであると考えられた。床反力の最大値は、ほとんどの被験者で増加が見られた。背屈・底屈可動域には大きな変化がなかったものの、背屈（ブレーキ）動作の速度は遅くなり、底屈（推進）動作の速度は速くなる傾向にあった。主働筋である下腿三頭筋の背屈動作時の神経筋活動は、いずれの被験者でも増加していた。一方、底屈局面においては、個人差が大きく、平均値としてはほとんど変化が見られなかった。背屈動作中の神経筋活動の増加が、背屈動作中の床反力の増加をもたらし、力積の増加に寄与したと考えられる。また、背屈動作中の力発揮の結果生じる最大床反力の増加は、底屈動作中の力積の増加に寄与した可能性が高い。今後、追加実験や詳細な分析を行い、明確な結論を得ていく予定である。