PURPOSE: The flexor digitorum longus and posterior tibial tendon as well as the perforating veins are located along the distal posteromedial tibial border. Adipose tissue may surround these structures and possibly play a role in reducing mechanical stress. This study aimed to examine the adipose tissue along the posteromedial tibial border via magnetic resonance imaging (MRI), ultrasound, and gross anatomical examination. METHODS: The lower legs of 11 healthy individuals were examined every 3 cm from the medial malleolus using MRI and ultrasound. The fat fraction was calculated using fat fraction images. In addition, the gross anatomy of the flexor digitorum longus origin and adipose tissue along the posteromedial tibial border was examined in seven fresh cadavers. The fat fraction was compared at different heights along the posteromedial tibial border and in Kager's fat pads; we also compared the height of the flexor digitorum longus origin and adipose tissue. RESULTS: In vivo, the adipose tissue was identified along the entire posteromedial tibial border using MRI and ultrasound. There was no significant difference in fat fraction between Kager's fat pads and the adipose tissue along the posteromedial tibial border, except at the 6 cm mark. All seven cadavers presented adipose tissue along the posteromedial tibial border, significantly more distal than the flexor digitorum longus origin. CONCLUSION: The adipose tissue was identified along the posteromedial tibial border via MRI, ultrasound, and gross anatomical examination; thus, this tissue may play a role in reducing friction and compressive stress in tendons.

We aimed to investigate the changes caused by focused extracorporeal shock wave pain therapy (f-ESWT) in patients with patellar tendinopathy by means of ultrasound imaging. We included 18 knees from 11 college athletes with patellar tendinopathy. We assessed the tendon thickness and blood flow of the patellar tendon using ultrasound imaging, rest pain using NRS and tenderness using a pressure pain gauge. We recorded four measurements: immediately before f-ESWT (PRE 1) and after f-ESWT (POST 1) and two weeks after the first irradiation before f-ESWT (PRE 2) and after f-ESWT (POST 2). Only the resting pain in both the first and second irradiations showed a significant difference immediately before and after the treatment. In terms of pain changes after two weeks later, we observed significant differences in the resting pain between PRE 1 and PRE 2 and also in the resting pain, tenderness and blood flow area between PRE 1 and POST 2. No significant difference was seen in the tendon thickness. We concluded that pain in the patellar tendon at rest decreased before and after irradiation, suggesting that f-ESWT may have influenced the nociceptive structures and had an analgesic effect.

BACKGROUND: Identifying the characteristics of physical function and muscle strength related to swing velocity is necessary for improving batting performance. The purpose of this study was to identify the factors related to swing velocity in youth baseball players. METHODS: 191 youth baseball players aged 7-13 years old participated and were divided into the Tee Ball (˂9.5 years) and Major (≥9.5 years) divisions. We measured the swing velocity for batting performance, medicine ball (MB) back throw and modified star excursion balance test (SEBT) for physical function, and hip muscle torque for lower extremity muscle strength. RESULTS: Height and MB back throw (β=0.403 and 0.380) for physical function (R2=0.646), and height and internal rotation (IR) torque of the step leg (β=0.620 and 0.216) in lower extremity muscle strength (R2=0.616) were all extracted as related independents for the multiple regression analysis on swing velocity in all subjects. Additionally, height, MB back throw and modified SEBT in the pivot leg (β=0.420, 0.324 and 0.218) for the Major division (R2=0.579), and IR torque of the pivot leg and step leg (β=0.555 and 0.525) for the Tee Ball Division (R2=0.568) were selected. CONCLUSIONS: Swing velocity was related to height, MB back throws on physical function, and IR torque of the stepping leg in lower extremity muscle strength in youth baseball players. Therefore, the explosive power and strength for stopping the body opposite to the hitting direction are considered necessary to increase the swing velocity.

The peak increase in lean mass in adolescents is delayed from peak height velocity (PHV), and muscle flexibility temporarily decreases as bones grow. If the decrease in muscle flexibility is caused by muscle elongation, the relationship between the exerted torque and the joint angle could change in adolescents. The purpose of this study was to investigate the change in the optimum angle of force production due to growth. Eighty-eight healthy boys were recruited for this study. Isokinetic knee extension muscle strength of the dominant leg was recorded. The outcome variable was the knee flexion angle when maximal knee extension torque was produced (optimum angle). The age at which PHV occurred was estimated from subjects' height history. We calculated the difference between the age at measurement and the expected age of PHV (growth age). A regression analysis was performed with the optimal angle of force exertion as the dependent variable and the growth age as the independent variable. Then, a polynomial formula with the lowest p-value was obtained. A significant cubic regression was obtained between optimum angle and growth age. The results suggest that the optimum angle of force production temporarily changes in male adolescence.

BACKGROUND: In understanding the onset factors associated with Plantar heel pain and the structure of heel fat pad, measuring its thickness is the most basic frequently reported evaluation. This study aimed to determine changes to heel fat pad thickness associated with age and gender and the relationship between heel fat pad thickness, age, and physique in Japanese. METHODS: This study was carried out in 1126 healthy individuals between the ages of 1 and 96 years. Participants were categorized according to age. Heel fat pad thickness was measured with an ultrasonography device using a linear ultrasonography probe. FINDINGS: Heel fat pad tends to become thicker from ages 1-5 to 30-44 years and thinner from ages 30-44 to 80-96 years. Heel fat pad thickness in males and females was similar within each group, and males had higher heel fat pad thickness than females of corresponding ages. Heel fat pad thickness of males had a good correlation with height and body mass. Moreover, male heel fat pad thickness had a fair correlation with age. Heel fat pad thickness of females had a moderate correlation with height and body mass and a fair correlation with age. INTERPRETATION: Heel fat pad thickness became thicker from ages 1-5 to 30-44 years and thinner from ages 30-44 to 80-96 years. Females had a lower heel fat pad thickness than males of corresponding ages. This result suggests that higher heel fat pad thickness in males is related to body mass and height.

It is important to understand the timing of the maximum increase of forearm-hand inertia value and lean body mass (LBM) of the shoulder girdle musculature when elbow injury frequently occurs. This study aimed to clarify the discrepancies of those in youth baseball players. Forty-three male baseball players (8- to 14-years-old) participated in this study. The forearm-hand inertia value and LBM of the shoulder girdle musculature were calculated using dual-energy X-ray absorptiometry (DXA). A cubic spline fit was applied to the annual increase forearm-hand inertia value and LBM of the shoulder girdle musculature for each chronological age and years from peak height velocity (PHV) age. As a result of cubic splines fitting, the peak timing for forearm-hand inertia value and LBM of the shoulder girdle musculature was 12.42 and 12.75 years in chronological age, -0.66 and -0.11 years in PHV age. Therefore, the peak timing of forearm-hand inertia value was about 4 months earlier in chronological age and half a year earlier in PHV age than LBM of the shoulder girdle musculature. Acquiring sufficient shoulder girdle musculature during the period when the growth of the shoulder girdle musculature cannot catch up with forearm-hand inertial value is necessary to reduce the elbow load while throwing.

The purpose of this study was to identify the growth changes of the inertial in baseball players from both chronological age and relative growth, and to play a part in the elbow injury prevention. The subjects were 184 baseball players from elementary school students to university students. A whole body scan was performed using a DXA device, and the forearm-and-hand inertia were calculated according to Ganley’s method of calculating the inertia. In addition, the inertia ratio was calculated by the forearm-and-hand inertia for the region of scapular lean mass and the inertia ratio of that under the condition of the ball holding. In addition, the allometry method was used to determine the inertia ratio and the inertia ratio of ball holding condition from the viewpoint of relative growth based on height. The inertial ratio showed the peak at the age of 12 or about 150 cm in height, suggesting an increased risk of elbow disorders at this time.

Previous studies suggest that marathon running induces lower extremity muscle damage. This study aimed to examine inter- and intramuscular differences in hamstring muscle damage after a marathon using transverse relaxation time (T2)-weighted magnetic resonance images (MRI). 20 healthy collegiate marathon runners (15 males) were recruited for this study. T2-MRI was performed before (PRE) and at 1 (D1), 3 (D3), and 8 days (D8) after marathon, and the T2 values of each hamstring muscle at the distal, middle, and proximal sites were calculated. Results indicated that no significant intermuscular differences in T2 changes were observed and that, regardless of muscle, the T2 values of the distal and middle sites increased significantly at D1 and D3 and recovered at D8, although those values of the proximal site remained constant. T2 significantly increased at distal and middle sites of the biceps femoris long head on D1 (p = 0.030 and p = 0.004, respectively) and D3 (p = 0.007 and p = 0.041, respectively), distal biceps femoris short head on D1 (p = 0.036), distal semitendinosus on D1 (p = 0.047) and D3 (p = 0.010), middle semitendinosus on D1 (p = 0.005), and distal and middle sites of the semimembranosus on D1 (p = 0.008 and p = 0.040, respectively) and D3 (p = 0.002 and p = 0.018, respectively). These results suggest that the distal and middle sites of the hamstring muscles are more susceptible to damage induced by running a full marathon. Conditioning that focuses on the distal and middle sites of the hamstring muscles may be more useful in improving recovery strategies after prolonged running.

踵骨下に存在する踵部脂肪褥は、heel fat padとも呼ばれる脂肪組織で、構成要素の異なる浅層のmicrochamber layer(MIC)と深層のmacrochamberlayer(MAC)の大きく2層から構成されており、歩行などの際にクッション機能として働く。本研究では、超音波B-modeによる押し込み手法の前後の変化量とMICとMACの硬度値の相関を検討し、クッション機能を評価する手法について検討することを目的とした。押し込み変化量とMICのSRとの相関は見られなかったが、MACのSRと有意な正の相関が見られた。RTE法による踵部脂肪褥の硬度測定は、MACの弾性評価に有用である。(著者抄録)

【はじめに・目的】 Functional Movement Screen（FMS）は，スポーツ動作を実施する際の損傷リスクを抽出するためのスクリーニングツールとして開発された。成長期を対象とした研究では，特定競技の選手を対象としたものが多い。本研究では，同一の学校に通う児童を対象にFMS得点と損傷との関連を明らかにすることを目的とした。 【方法】 同一市内の3校に通う小学4～6年生132名（男子65名，女子67名）を対象とした。FMSの7種目を実施後，損傷の発生状況に関して6ヶ月間追跡調査を実施した。 【倫理的配慮】 演者の所属機関の倫理審査委員会の承認（承認番号：2017-255），対象者の同意を得て実施した。 【結果】 6カ月間で132名中41名に損傷発生があった。TSPUでは損傷が発生した人の得点が有意に低かった（p=0.004）。また，HSでは損傷が発生した人の得点が有意に高い結果となった（p=0.005）。ASLRでは，男子のみ下肢損傷が発生した人の得点が有意に高かった（p=0.021）。 【考察】 TSPUはstabilityの項目であるため，損傷を予防するためには体幹の安定性が必要であることが示唆された。HSとASLRの得点が損傷発生群で高値となったのは，より活動的な者に損傷が発生した可能性がある。今後，損傷発生時の状況や運動実施時間を考慮に入れた検討が必要である。先行研究ではFMSの合計点で損傷発生を予測していたが，本研究では合計点ではなくTSPUの評価を行うことで損傷発生を予測できる可能性が示唆された。

【はじめに・目的】 高校生野球選手のL3-5椎弓根の輝度を打撃・非打撃側で比較することにより，打撃動作の特性である一側性の運動が腰椎椎弓根に及ぼす影響を検討することを目的とした。 【方法】 対象は高校生野球選手24名とした。MRI装置を用いて第3腰椎（L3）から第5腰椎（L5）の矢状断および水平断画像をSTIRで撮像した。撮像した画像を解析用ソフトに取り込み，椎体に対する左右の椎弓根の相対輝度を算出した。左右差を一般化するために打撃側の腰椎椎弓根相対輝度を打撃側相対輝度，逆側を非打撃側相対輝度と表した。さらに非打撃側相対輝度を打撃側相対輝度で除し，腰椎ごとに非打撃側/打撃側比を求めた。統計解析は，L3-L5の打撃・非打撃側相対輝度の差を対応のあるt検定，またL3，L4およびL5における相対輝度の割合のそれぞれの関係をPearsonの積率相関係数を用いて算出した（p＜0.05）。 【倫理的配慮】 演者の所属機関の倫理審査委員会の承認（承認番号：2013-167），対象者の同意を得て実施した。 【結果】 L3-L5における打撃・非打撃側の相対輝度には有意な差は認められなかった（p=0.702，0.250，0.766）。非打撃側/打撃側比に関してL4とL5との間にのみ正の相関が見られた（p=0.003）。 【考察】 L3-5において打席側に関わらず左右椎弓根に損傷が起こりうると言える。一方，回旋動作において負荷の大きいとされるL4とL5に関しては打撃側または非打撃側の同側に高輝度が見られることが示唆された。