BACKGROUND: Growth-specific physical characteristics in adolescence may mediate throwing-related loads and movement patterns associated with elbow injuries. In a previous study, the authors calculated the forearm-hand inertia, which is the moment of inertia centered at the elbow joint. PURPOSE: To determine the relationship of forearm-hand inertia values with throwing motion patterns and elbow valgus load in adolescent baseball players. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 35 adolescent baseball players underwent measurements by dual-energy x-ray absorptiometry (DXA) scans and a throwing trial. Forearm-hand inertia was determined as the joint moment around the elbow using the subregion analysis mode of DXA. Elbow valgus torque and ball speed during throwing were measured using a dedicated sensor and speed gun, and throwing efficiency was calculated by dividing the elbow valgus load by the ball speed. Players were divided according to the throwing motion pattern in which maximum acceleration occurred: pelvis-upper arm-forearm (proximal-to-distal sequencing [PDS] group; n = 19) or pelvis-forearm-upper arm (proximal upper extremity [PUE] group; n = 16). The groups were compared in terms of ball speed, elbow valgus torque, throwing efficiency, and forearm-hand inertia using t tests and analysis of covariance, with forearm-hand inertia as covariates. The chi-square test was used to examine the relationship between throwing motion patterns and forearm-hand inertia. RESULTS: The PUE group had a higher elbow valgus load (effect size [ES] = 0.65; P = .03), throwing efficiency (ES = 0.63; P = .02), and forearm-hand inertia values (ES = 0.64; P = .04) than the PDS group. In addition, a significant relationship was observed with throwing patterns when forearm-hand inertia values were 350 kg·m2 (OR, 2.36; 95% CI, 1.09-5.12; P = .012) and 400 kg·m2 (OR, 1.68; 95% CI, 0.99-2.85; P = .037). CONCLUSION: Study results indicated that growth-specific physical characteristics in adolescent baseball players exhibited in forearm-hand inertia mediated the relationship between high elbow valgus and poor throwing efficiency caused by poor throwing motion patterns. CLINICAL RELEVANCE: A better understanding of the details in muscle function with throwing mechanics may prevent future injuries.

BACKGROUND: The purpose of this study was to clarify the differences in the movement of the superficial microchambers and deep macrochambers of the heel fat pad during loading and unloading movements, and to clarify the influence of height and weight on this movement. METHODS: The subjects were 21 healthy adults. The right foot was placed on an evaluation instrument stand made of polymethylpentene (PMP) resin plate, and the left foot was placed on a scale stand used to adjust the amount of load. When measuring, the heel fat pad is divided into the superficial microchamber layer and the deep macrochamber layer, and the thickness due to loading from 0% to 100% of the body weight and unloading from 100% to 0% is measured. Measurement was performed every 20% using an ultrasound imaging device. We also examined the rate of change in the thickness of the superficial and deep layers of the heel fat pad when applying 100% load (end load) from 0% load (unload). RESULTS: No changes were observed in the superficial layer of the heel fat pad during unloading, but significant changes were observed in the deeper layers. Additionally, the thickness of the microchamber and macrochamber layers tended to increase under each loading condition as the height and weight increased. On the other hand, the rate of change in the thickness of the macrochamber layer tended to decrease. CONCLUSION: The microchamber layer and the macrochamber layer of the heel fat pad may have different functions. As height and weight increase, the thickness of the microchamber and macrochamber layers may increase, and the rate of change in the thickness of the macrochamber layer appears to decrease. Although the thickness increases as the load increases, we found that the related elasticity decreases. LEVEL OF EVIDENCE: Level Ⅳ, cross-sectional survey study.

BACKGROUND: This study aimed to investigate the thickness changes of the heel fat pad and the plantar fascia associated with loading and unloading in healthy individuals and patients with heel pain and reveal the differences between them. METHODS: The study included adult male participants with (n = 9) and without (n = 26) heel pain. The participants placed their right foot on an evaluation apparatus with a polymethylpentene resin board (PMP), while their left foot was positioned on a weighing scale used to adjust the loading weight. The heel fat pad was differentiated into superficial Microchamber and deep Macrochamber layers. These layers and plantar fascia thickness were measured using an ultrasonographic imaging device at loading phase ranging from 0% to 100% of their body weight and unloading phase from 100% to 0%. Additionally, the study examined the thickness change ratios of the superficial and deep heel fat pad layers when the load increased from 0% (unload) to 100% (full load). RESULTS: In healthy individuals and patients with heel pain, no significant thickness changes were observed in the Microchamber layer of the heel fat pad or the plantar fascia during loading and unloading evaluations. However, significant thickness changes were observed in the Macrochamber layer of the heel fat pad, and the pattern of change differed between the loading and unloading phases. Additionally, patients with heel pain showed differences in the thickness change and thickness change ratios of the microchamber and macrochamber layers of the heel fat pad during both loading and unloading phases. The thickness of the plantar fascia did not show significant differences between both groups. CONCLUSION: Compared with healthy individuals, in our relatively small study, patients with heel pain had greater deep fat pad compression in loading and less recovery after load removal. This finding suggests that these patients have different intrinsic fat pad function and related morphology than those without heel pain. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Background:

Differences in the physical characteristics of bilateral and unilateral lumbar bone stress injuries (BSIs) are unknown.

Purpose:

To compare bilateral and unilateral lumbar BSIs in adolescent male soccer players, with a focus on lumbopelvic alignment.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 78 players (age range, 12-15 years) from a local soccer club who had magnetic resonance imaging (MRI) evaluations were included in the study. Lumbopelvic alignment and lumbar BSI were evaluated using short-tau inversion recovery and 3-dimensional LAVA on 3-T MRI; lumbar BSI was defined as the presence of bone marrow edema and/or the complete and incomplete fracture in the pars region on the MRI. Pelvic tilt (PT) and pelvic outflare angles were assessed on the kicking and pivoting sides, and asymmetry for each parameter was calculated by subtracting the kicking side from the pivoting side. In addition, the lumbar lordosis (LL), sacral slope (SS), and SS relative to LL (calculated by subtracting LL from the SS) were assessed. One-way analysis of variance was performed to compare lumbopelvic alignment in players with bilateral BSI, unilateral BSI, or no abnormal findings (controls).

Results:

No significant differences were found regarding lumbopelvic alignment between the players with bilateral versus unilateral lumbar BSI. PT asymmetry was significantly greater in both players with bilateral lumbar BSI and unilateral lumbar BSI compared with controls ( P = .018 and P = .016, respectively). In addition, SS relative to LL was significantly greater in players with bilateral lumbar BSI compared with controls ( P < .001).

Conclusion:

Although there were no significant lumbopelvic alignment differences between bilateral and unilateral BSI, players with bilateral BSI exhibited increased sacral anterior tilt relative to the LL, and the pelvis was more posterior on the pivoting side than on the kicking side in both players with bilateral BSI and unilateral BSI. Our results suggest that lumbopelvic alignment assessment may contribute to the management strategy for players with lumbar BSI and to the identification of players at high risk of lumbar BSI.

Abstract

Background

Identifying the characteristics of batting mechanics, such as the proper angle and position of each body segment in youth baseball players, is important for proper instructions. This study aimed to identify the age-related changes in batting kinematics including rotational and separational movements of the head, upper trunk, pelvis, and arms, in youth baseball players.

Methods

Over the three seasons, we measured the batting motion of baseball players aged 6- to 12 years using three high-speed cameras. Participants were divided into six age categories according to the little league eligibility rules (players were classified according to their age as of July 31 of a given year). Toss batting was performed using an automatic tossing machine set obliquely in front of the batter. Additionally, we analyzed the rotation angles of the head, upper trunk, pelvis, and arm direction, and the separation angles—calculated using the difference of each rotational angle and the head movement distance and step width—at five points in batting phase: stance, load, foot contact, pre-swing, and ball contact. Finally, 17 players from under 8 (U8, i.e., approximately 7–8 years) to U10 and 13 from U11 to U13 were analyzed. A one-way repeated measures analysis of variance was performed to analyze age-related changes in batting kinematics.

Results

Several age-related changes in batting kinematics at various batting point were observed. The head-to-upper trunk separation angle increased with age from U8 to U10 during the foot contact (effect sizes [ES] = 0.658) and from U11 to U13 during the pre-swing (ES = 0.630). Additionally, the U13 showed a significantly increase in the upper and pelvis separation angles during load, foot contact, and pre–swing compared with U11 and U12 (ES = 0.131, 0.793, and 0.480).

Conclusion

Various changes in batting kinematics occurred among each age group. Notably, U12 and U13 had the greater upper trunk-to-pelvis separation angle at foot contact and pre-swing compared to U11. Therefore, it would be important for the instruction of younger baseball players to understand the underdevelopment of trunk separation when batting and encourage the acquisition of such separation movements.

BACKGROUND: Risk factors for throwing injuries related to pitching mechanics are unknown. Insufficient pelvic rotation during pitching may be a risk factor for shoulder and elbow injury. HYPOTHESIS: This cohort study aimed to identify biomechanics risk factors for throwing injuries in young baseball players. We hypothesized that excessive mechanical load and motion errors would be risk factors for throwing injuries. METHODS: Young baseball pitchers (aged 8-9 years) were recruited from regional baseball leagues between December 2016 and December 2019. Pitching measurements were performed before the start of each season and after the end of the last season in December 2019. The trunk tilt angular displacement, pelvic rotation angular displacement, and forearm rotation angle were calculated using a markerless motion capture system. We also measured elbow varus torque using an accelerometer. After the initial test session, each participant was followed-up for 3 years to determine the occurrence of throwing injuries. Players with throwing shoulder and elbow injuries were categorized into the throwing injury group, and those without shoulder and elbow pain for 3 years were categorized into the non-injured group. RESULTS: In this study, 97 baseball pitchers completed a 3-year follow-up. Among those participants, 66 (68.0%) had throwing injuries. A significant difference was observed between the throwing injury and non-injured groups, whereby the injured players had less pelvic rotation angular displacement. CONCLUSION: Insufficient pelvic rotation during pitching is a newly discovered risk factor related to throwing injuries.

(目的)Magnetic resonance imaging(MRI)を用いた仙骨傾斜角評価を基準とし,傾斜計を用いた腰仙椎角の計測の精度を検証とすること,予測回帰式を探索することを目的とした.(方法)中学生の男子70名を対象とし,腰部のMR撮像および傾斜計を用いた腰仙椎アライメント測定を実施した.得られたMR画像から脊柱の正中矢状断を抽出し,仙骨の上縁と画像の水平線をなす角を仙骨傾斜角として算出した.また,腰仙椎角の測定には傾斜計を用い,腰仙椎部に傾斜計の0°の軸が通る位置で計測を行った.そしてBland-Altmanプロットを用いた両測定法の一致度の検証に加え,MR撮像による仙骨傾斜角と傾斜計による腰仙椎角との関係を線形回帰分析によって検討した.(結果)MRIを用いた仙骨傾斜角と傾斜計による腰仙椎角との差で求められる固定誤差は10.06±3.29°を示した一方で,比較誤差および偶然誤差は小さかった.MRIを用いた仙骨傾斜角と傾斜計による腰仙椎角との間には有意な関連が見られ,予測回帰式はy=0.85x+13.49が得られた.(結論)傾斜計を用いた腰仙椎角の評価はMRIを用いた仙骨傾斜角と比べて計測値が過小評価されやすい可能性がある.しかしながら比例および偶然誤差は小さく,傾斜計で得られる数値を基に仙骨傾斜角の予測が可能となると考える.(著者抄録)

バスケットボールにおける足関節捻挫要因である,ポジション(ガード,フォワード,センター),受傷場面(試合,練習),受傷機転(接触の有無及び接触部位(足・足関節部,足・足関節部以外))の3点を複合的に検討し,足関節捻挫発生率との関連性を明らかにするために,大学女子バスケットボール選手延べ60名を対象に3シーズン33ヵ月の疫学調査を行った.単一因子での検討では,Forward,試合時,足部同士の接触による発生率がそれぞれ最も高かった.複数因子での検討では,Guardで試合時の足部同士の接触による発生率が最も高かった.単一因子と複数因子の検討間で結果に差異があることから,単一因子ではなく,複数因子によるより詳細な検討の必要性が明らかとなった.(著者抄録)

バスケットボールにおける足関節捻挫要因である,ポジション(ガード,フォワード,センター),受傷場面(試合,練習),受傷機転(接触の有無及び接触部位(足・足関節部,足・足関節部以外))の3点を複合的に検討し,足関節捻挫発生率との関連性を明らかにするために,大学女子バスケットボール選手延べ60名を対象に3シーズン33ヵ月の疫学調査を行った.単一因子での検討では,Forward,試合時,足部同士の接触による発生率がそれぞれ最も高かった.複数因子での検討では,Guardで試合時の足部同士の接触による発生率が最も高かった.単一因子と複数因子の検討間で結果に差異があることから,単一因子ではなく,複数因子によるより詳細な検討の必要性が明らかとなった.(著者抄録)

Abstract

Background

A flat foot is a common cause of chronic sports injuries and therefore many opportunities for arch support interventions exist. However, young athletes change their foot morphology due to developmental influences even without intervention. Therefore, developmental influences need to be considered when examining the effects of arch support, but there have not been sufficient longitudinal studies to date. This study aimed to determine the effect of the arch support intervention by performing a 9-weeks arch support intervention on the foot morphology and cross-sectional area of the foot muscles in flat-footed young athletes. Thirty-one elementary school boys (Age 11.4 ± 0.5 years, Height 145.2 ± 7.4 cm, Weight 38.8 ± 8.3 kg, BMI 18.2 ± 2.2 kg/m²) with a decreased medial longitudinal arch in the foot posture index were selected as participants from a local soccer club and randomly divided into two groups.

Methods

In one group, in the intervention period, an existing arch supporter was used to provide arch support, while in the other group, no special intervention was provided in the observation period. To account for developmental effects, the intervention study was conducted as an 18-weeks crossover study in which the intervention and observational phases were switched at 9 weeks after the intervention. Foot morphology was assessed using a three-dimensional foot measuring machine, and the cross-sectional area (CSA) of the internal and external muscles of the foot was assessed using an ultrasound imaging device. We examined the effect of the intervention by comparing the amount of change in the measurement results between the intervention and observation periods using corresponding t-tests and Wilcoxon signed-rank sum test, analysis of covariance methods.

Results

After adapting the exclusion criteria, 14 patients (28 feet) were included in the final analysis. The CSA of the abductor hallucis muscle (ABH) increased 9.7% during the intervention period and 3.0% during the observation period (p = 0.01). The CSA of the flexor digitorum longus muscle (FDL) increased 7.7% during the intervention period and 4.2% during the observation period (p = 0.02).

Conclusion

A 9-weeks arch supporter intervention may promote the development of the ABH and FDL CSA in young flat-footed soccer players.

<jats:p>The timing and tempo of growth rate varies inter-individually during adolescence and can have an impact on athletic performance. This study aimed to determine the difference in growth rate for each maturity status. We combined data collected both retrospectively and prospectively from 78 adolescent boys aged 12 years old; growth charts were collected from their elementary school records, and the height of each participant was subsequently measured every six months over a period of two years. Take Off Age (TOA), Peak Height Velocity Age (PHVA), and Final Height Age (FHA) were estimated using the AUXAL 3.1 program. Growth Tempo 1 and 2 were calculated by dividing the height increase by the time difference between TOA and PHVA, and FHA, respectively. Our results showed three group differences based on the maturation status of PHVA: Growth Tempo 1 and 2 were both higher in the early than during middle and late maturation. Additionally, entering the height at each event as a covariate, the group differences for Growth Tempo 1 did not change; however, for Growth Tempo 2, group differences were eliminated. Therefore, we conclude that during early maturation, growth from TOA to PHVA occurs rapidly and in a shorter period.</jats:p>

【目的】健常成人正常足と比較した回内足の足内在筋および外在筋の筋横断面積(以下、CSA)の違いを明らかにすることである。【方法】対象は健常成人25名50足(男性15名女性10名、年齢24.3±1.4歳、身長167.5±7.7cm、体重62.4±12.6kg、BMI22.1±3.0kg/m2)とした。CSAに関しては超音波画像診断装置を用いて、短母趾屈筋、母趾外転筋、短趾屈筋、長趾屈筋(以下、FDL)、長母趾屈筋(以下、FHL)、腓骨筋、後脛骨筋の測定を行った。その後Foot posture indexを用いて足部形態の評価を行い、回内足群、正常足群に群分けし、群間での各筋CSAの比較を行った。【結果】回内足群16足(男5名8足、女6名8足)では、正常足群32足(男11名20足、女8名12足)と比較しFDL(p=0.007)、FHL(p=0.04)のCSAが有意に大きかった。【結論】回内足群は正常足群と比較してFDL、FHLのCSAが有意に大きく、能動的足部支持機能としてはFDL、FHLが優位に機能することが示唆された。回内足に対して足部筋のトレーニングなどを行う際には、足部形態の特徴に留意する必要がある。(著者抄録)

【目的】中学生野球選手における投球障害肩の既往が上肢分節重量および肩甲帯除脂肪量に与える影響を明らかにすることを目的とした。【方法】対象は中学1〜3年生の野球選手149名とし、その内16名をInjured Shoulder群、133名をNon Injured群に分類し、比較検討を行った。測定はDXA装置を用い、whole body modeを用いて全身スキャンを行った。そしてSubRegion機能を用いて上肢を分画し、上腕、前腕、手部の重量、ならびに肩甲帯部の除脂肪量を算出した。上肢、上腕、前腕、手部の重量、肩甲帯除脂肪量、肩甲帯除脂肪量に対する上腕重量の群間比較にはt検定もしくはMann-WhitneyのU検定を用いた。また、上腕重量、上肢重量、肩甲帯除脂肪量については群間の体格差を考慮するため、体重を共変量とする共分散分析を実施した。【結果】前腕重量、上腕重量、上肢重量はInjured Shoulder群がNon Injured群と比較して有意に高値を示した(p=0.045、0.014、0.028)。また、肩甲帯除脂肪量に対する上腕重量はInjured Shoulder群がNon Injured群よりも有意に高値を示した(p=0.045)。共分散分析の結果、肩甲帯除脂肪量はInjured Shoulder群がNon Injured群と比較して有意に低値(p=0.028)を示した一方、上肢および上腕重量は高値を示した(p=0.049、0.046)。【結論】投球障害の既往を有する中学野球選手は上肢重量に対して肩甲帯筋量が不足することが明らかとなった。肩痛の既往は肩障害再発の危険因子となることから、肩甲帯除脂肪量の発育がピークとなる中学生期に肩甲骨周囲筋のトレーニングを介入することは再発予防に貢献する可能性がある。(著者抄録)

膝関節は下肢の中心に位置し人々のADLに重要な役割を担っている。その膝関節の正常な働きを可能にするのが動作の潤滑さと負荷の緩衝に寄与する軟骨である。軟骨厚は近年日本で増加する変形性膝関節症の発症と進行を説明する1つの重要な尺度であり、一般的に厚い軟骨は薄い軟骨よりも衝撃緩衡能力に優れ健康な軟骨と考えられている。運動と軟骨厚の関係を明らかにし後年においても正常な軟骨を保つ生活習慣を促すことは急務である。本研究では、超音波画像診断装置を用いて大学生の膝関節軟骨厚を測定し運動習慣や運動様式による違いを明らかにすることを目的とした。対象は大学生510名(男子356名、女子154名)、計1020膝とした。超音波画像診断装置を用いて大腿骨内側顆荷重部の軟骨厚を測定し、異なる運動習慣と運動様式を持つ群間で比較した。男子においては、バスケットボールや陸上競技など、下肢に高頻度、高強度の負荷がかかる競技において軟骨厚が厚かった。また、男子、女子ともに継続的な運動を行っていない非運動群ならびに荷重負荷のかからない競技である競泳は、他の群に比べ軟骨厚が薄い傾向が見られた。本研究結果から、運動習慣や下肢への荷重負荷が加わる運動の実施が軟骨厚を厚くしている可能性が示唆された。したがって、若年期の運動により正常な軟骨厚を保つことが、後年においても関節の働きを維持することに役立つ可能性が考えられる。(著者抄録)

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.

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.

本研究は野球選手の発育に伴う慣性値の変化を暦年齢ならびに相対発育の2つの発育指標から明らかにし，肘障害予防の一端を担うことを目的とした．対象は小学生から大学生までの野球選手133名とした．DXA装置を用いて全身スキャンをし，Ganleyの慣性モーメントの算出法に準じて，前腕・手部慣性値を算出した．また，肩甲帯部除脂肪量に対する前腕・手部慣性値を示す慣性値比，野球ボール保持想定での慣性値比を求めた．さらにアロメトリー法を用いて身長に基づく相対発育の観点から慣性値比および野球ボール保持想定での慣性値比の変位点を求めた．慣性値比は12歳頃，または身長約150cmでピークとなり，この時期には肘障害のリスクが高まることが示唆された．

本研究は発育過程にある野球選手の前腕・手部慣性値の変化、ならびに肩甲帯部除脂肪量に対する前腕・手部慣性値の変化を明らかにすることで、肘障害リスクの考察の一助とすることを目的とした。対象は小学生から高校生までの野球選手120名とし、DXA装置を用いて全身スキャンを行った。そしてSub-Region機能を用い、最小にした関心領域を投球側の肘関節から手指末梢まで並べ、それぞれの質量データを抽出した。その後n番目までの質量×関節からの距離の二乗の積分値をもって前腕・手部慣性値とした。また、上肢を支持する肩甲帯部除脂肪量を算出し、肩甲帯除脂肪量に対する前腕・手部慣性値で求められる慣性値比を算出した。前腕・手部慣性値は線形に近い形で回帰したが、暦年齢において11歳頃、PHV経過年数において約2年前を境に傾きが増加傾向にあった。慣性値比は暦年齢で12歳頃、PHV経過年数で約-2年まで増加し、その後はやや減少傾向にあるもののほぼ横ばいであった。暦年齢で12歳頃、また身長最大増加時期を迎える約2年前までは上肢を支持する肩甲帯部除脂肪量が相対的に不足しており、肘への負荷が高まり障害発生の一要因となりうる。(著者抄録)

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)

【緒言】健常投手、肩痛投手および一般人を対象とし肩甲骨面上での外転角度の違いによる肩関節位置覚を硬式球保持・非保持で比較することで、肩障害ならびに投手の競技特性が肩関節位置覚に与える影響を明らかにすることを目的とした。【方法】対象は健常投手9名、肩痛投手6名、一般人9名とした。肩関節位置覚測定はBalkeらの方法を改良し、上腕近位部にレーザーポインターを装着して行った。座位姿勢にて、肩関節水平内転30°上での外転60、90、および120°の関節位置覚測定を硬式球保持・非保持の2条件で行った。【結果】硬式球保持時では、外転60および90°におけるcontrol群と野球健常群との間、外転120°における野球健常群と野球肩痛群との間に有意な差が見られた(p=0.017および0.040、0.002)。さらに野球健常群は外転60と120°、90と120°との間に有意な差が認められた(ともにp=0.005)。【考察】固有感覚には学習の要素があり、利き手の方が高値を示すとされている。このことから肩関節外転位で投球動作を繰り返し行う投手の競技特性の影響が考えられる。また、随意運動であるリリース動作の繰り返しが健常投手の肩関節位置覚の高値につながったと推察できる。【結論】健常投手において、硬式球保持時の肩甲骨面上における外転120°での関節位置覚は高値を示し、競技特性を反映する可能性が示唆された。(著者抄録)