<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>

<italic><bold>Purpose</bold>:</italic> The optimal load for maximal power output during hang power cleans (HPCs) from a mechanical perspective is the 1-repetition-maximum (1RM) load; however, previous research has reported otherwise. The present study thus aimed to investigate the underlying factors that determine optimal load during HPCs. <italic><bold>Methods</bold>:</italic> Eight competitive Olympic weight lifters performed HPCs at 40%, 60%, 70%, 80%, 90%, 95%, and 100% of their 1RM while the ground-reaction force and bar/body kinematics were simultaneously recorded. The success criterion during HPC was set above parallel squat at the receiving position. <italic><bold>Results</bold>:</italic> Both peak power and relative peak power were maximized at 80% 1RM (3975.7 [439.1] W, 50.4 [6.6] W/kg, respectively). Peak force, force at peak power, and relative values tended to increase with heavier loads (<italic>P</italic> &lt; .001), while peak system velocity and system velocity at peak power decreased significantly above 80% 1RM (<italic>P</italic> = .005 and .011, respectively). There were also significant decreases in peak bar velocity (<italic>P</italic> &lt; .001) and bar displacement (<italic>P</italic> &lt; .001) toward heavier loads. There was a strong positive correlation between peak bar velocity and bar displacement in 7 of 8 subjects (<italic>r</italic> &gt; .90, <italic>P</italic> &lt; .01). The knee joint angle at the receiving position fell below the quarter-squat position above 70% 1RM. <italic><bold>Conclusions</bold>:</italic> Submaximal loads were indeed optimal for maximal power output for HPC when the success criterion was set above the parallel-squat position. However, when the success criterion was defined as the quarter-squat position, the optimal load became the 1RM load.

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 purpose of the present study was to elucidate how plyometric training improves stretch-shortening cycle (SSC) exercise performance in terms of muscle strength, tendon stiffness, and muscle-tendon behavior during SSC exercise. Eleven men were assigned to a training group and ten to a control group. Subjects in the training group performed depth jumps (DJ) using only the ankle joint for 12 weeks. Before and after the period, we observed reaction forces at foot, muscle-tendon behavior of the gastrocnemius, and electromyographic activities of the triceps surae and tibialis anterior during DJ. Maximal static plantar flexion strength and Achilles tendon stiffness were also determined. In the training group, maximal strength remained unchanged while tendon stiffness increased. The force impulse of DJ increased, with a shorter contact time and larger reaction force over the latter half of braking and initial half of propulsion phases. In the latter half of braking phase, the average electromyographic activity (mEMG) increased in the triceps surae and decreased in tibialis anterior, while fascicle behavior of the gastrocnemius remained unchanged. In the initial half of propulsion, mEMG of triceps surae and shortening velocity of gastrocnemius fascicle decreased, while shortening velocity of the tendon increased. These results suggest that the following mechanisms play an important role in improving SSC exercise performance through plyometric training: (1) optimization of muscle-tendon behavior of the agonists, associated with alteration in the neuromuscular activity during SSC exercise and increase in tendon stiffness and (2) decrease in the neuromuscular activity of antagonists during a counter movement.

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.

The purpose of this study was to examine the acute effects of an ascending intensity squat protocol consisting of single-repetition exercises on subsequent vertical jump performance. Fourteen college weightlifters attended 2 testing sessions: squat (SQ) and control (CON) conditions. In the SQ condition, squat exercises with incremental loads (20% 1 repetition maximum [RM], 40% 1RM, 60% 1RM, 80% 1RM, and maximal isometric [MI] half-squat exercise) were performed with a time interval of 3 minutes after submaximal cycling and static stretching. Maximum vertical jump height was measured at the beginning of the session and after cycling, static stretching, and each squat exercise in the SQ condition. In the CON condition, vertical jump height was measured at the same times with the subject resting on a chair after cycling and stretching. Vertical jump height gradually increased after 60% 1RM, 80% 1RM, and MI half-squat exercises compared with baseline values (i.e., first trial of vertical jump), whereas no change was observed in the CON condition. These results suggest that an ascending intensity squat protocol consisting of single-repetition exercises of sufficient intensity can be useful for athletes who require high muscular power. © 2014 National Strength and Conditioning Association.

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.