Purpose The anterior cruciate ligament‐return to sports after injury (ACL‐RSI) scale assesses the psychological impact of returning to sports (also referred to as psychological readiness) after ACL reconstruction. The aim of this study was to evaluate important measurement properties of the Japanese version of ACL‐RSI scale. Methods Ninety‐three participants who underwent ACL reconstruction filled out the Japanese version of ACL‐RSI scale, the Tampa scale for kinesiophobia (TSK), the International Knee Documentation Committee‐Subjective Knee Form (IKDC‐SKF), and Knee injury and Osteoarthritis Outcome Score (KOOS). To assess test re‐test reliability, 50 of the 93 participants re‐answered the Japanese version of ACL‐RSI scale within 10 days. Floor and ceiling effects, internal consistency, construct validity, and reliability of the Japanese version of ACL‐RSI scale were analysed. Results There were no floor and ceiling effects. The Japanese version of ACL‐RSI scale showed good internal consistency (Cronbach's alpha = 0.912). It was positively correlated with total points of IKDC‐SKF and the Lysholm score, and with the all sub‐categories of the KOOS, and it was negatively correlated with the TSK. Reliability of the Japanese version of ACL‐RSI scale was satisfactory. Conclusion The Japanese version of ACL‐RSI scale has acceptable measurement properties. It can be a useful for evaluation of psychological readiness for return to sports in Japanese athletes who undergo primary ACL reconstruction. Information provided by the Japanese version of the ACL‐RSI scale may also help to identify athletes who find return to sport a challenge, and guide conversations regarding treatment and rehabilitation plans. Level of evidence II.

BACKGROUND: Muscle activation during isometric contraction can be changed using an external-focus instruction method. OBJECTIVE: To explore and compare the activity of eight upper limb and trunk muscles during isometric chest squeeze exercises, performed in the same posture with and without the exertion of control to avoid crushing an object. METHODS: Muscle activation by an isometric chest squeeze with 45∘ shoulder abduction and forearm pronation was examined. Isometric chest squeeze exercises were performed while holding objects with maximum pressure, and with exerted control to avoid crushing the object Muscle activation was measured by surface electromyography. RESULTS: During the exercises performed while exerting control to avoid crushing the object the lower trapezius (p< 0.001) and latissimus dorsi (p= 0.03) showed significantly higher activity. During the exercises performed without control, the upper trapezius, serratus anterior, and pectoralis major showed significantly higher activity (p= 0.016, p< 0.001, p< 0.001, respectively). CONCLUSIONS: This novel isometric exercise can increase the scapular muscles in the intermediate range of the glenohumeral joint. Therefore, it may assist in improving sport performance, in preventing injuries and in rehabilitation following musculoskeletal injuries.

Background : Various musculoskeletal screening and functional performance tests are used to evaluate physical condition. However, validated analysis tools that can identify gaps in pain knowledge during athletes' daily training are lacking. This study aimed to investigate the relationship between pain intensity in athletes during their daily training and the KOJI AWARENESS™ test in order to determine whether body dysfunction is related to pain among athletes. Methods : This cross-sectional study was conducted in a fitness center at the authors' affiliated institution. Thirty-five athletes (17 women and 18 men) aged 20-40 years were selected for study participation. KOJI AWARENESS™ self-evaluated test scores and pain intensity during daily training, as assessed on the numerical rating scale (NRS), were recorded. Results : The KOJI AWARENESS™ score showed a strong negative correlation with the NRS score for pain intensity during daily training (r = −0.640, P < 0.001).There was a significant negative correlation between KOJI AWARENESS™ and NRS scores, even when body mass index, sex, and age were entered as control variables. Conclusions : KOJI AWARENESS™ was highly accurate in detecting pain in athletes during their training.

Study Design. Outcome study to determine the construct validity and reliability of the Japanese version of the Lumbar Stiffness Disability Index. Objective. The aim of this study was to evaluate the psychometric measurement properties of the Japanese version of the Lumbar Stiffness Disability Index (J-LSDI) following lumbar spinal surgery in order to assess its construct validity and reliability. Summary of Background Data. The LSDI was designed and validated as a tool to assess functional impacts of lumbar spine stiffness and diminished spinal flexibility. A Japanese version has been developed, but its construct validity and reliability have not been evaluated. Methods. A Pearson correlation coefficient was calculated using flexion and extension range of motion, Oswestry Disability Index (ODI) and Tampa Scale for Kinesiophobia (TSK) as external standards to evaluate construct validity. An intraclass correlation coefficient (ICC) and a Bland-Altman analysis were used to evaluate test–retest reliability. Results. A total of 244 patients following lumbar spinal surgery participated in the study. Fifty one of the 244 patients participated in the reliability study. The ICC of the J-LSDI for test–retest reliability was 0.89 (95% confidence interval, 0.79–0.93). There was no systematic error found in the results of the Bland-Altman analysis. One hundred ninety-three of the 244 patients participated in the validity study. There were significant correlations between the J-LSDI and trunk flexion range of motion (r = −0.66), extension (r = −0.51), ODI (r = 0.62), and TSK (r = 0.38). Conclusion. The construct validity and reliability of the Japanese version of the LSDI were confirmed. The J-LSDI can be used to evaluate lumbar stiffness and associated disability in Japanese patients following lumbar spinal surgery. Level of Evidence: 2

Perturbation exercises enhance lower limb and trunk muscles, and adding swing perturbation while loading during exercise might improve muscle activation or strength. This study aimed to check variations in trunk and lower limb muscle activity during conventional isometric squats, and whether it will change with or without swing using the Hammerobics-synchronized squat method. Twelve healthy men participated in this study. Activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured using surface electromyography during a Hammerobics-synchronized squat and conventional isometric squat. Muscle activities were statistically compared between squat methods. Hammerobics-synchronized squats significantly activated the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, semitendinosus, and multifidus muscles, in both phases, compared with the conventional isometric squats. The Hammerobics-synchronized squat exercise can be considered for trunk and foot stability exercise.