Effect of toe-out gait modification on patellofemoral joint loading.

BACKGROUND: Toe-out gait has been proposed as a conservative treatment to reduce medial tibiofemoral joint loading. However, patellofemoral joint loading during toe-out gait is not yet understood. RESEARCH QUESTION: Does the toe-out gait modification affect patellofemoral joint loading? METHODS: Sixteen healthy adults were enrolled in this study. The natural gait and toe-out gait were measured using a three-dimensional motion analysis and a force plate. The knee flexion angle and external knee flexion moment during the stance phase were calculated. Thus, dynamic knee joint stiffness, a proxy of patellofemoral joint loading, was defined as a linear regression of the knee flexion moment and knee flexion angle during the early stance. Additionally, the peak patellofemoral compressive force during the early stance was calculated using a musculoskeletal simulation. A paired t-test was used to compare these biomechanical parameters during the natural gait and toe-out gait. RESULTS: The toe-out gait significantly increased the peak patellofemoral compressive force (mean difference = 0.37 BW, P = 0.017) and dynamic knee joint stiffness (mean difference = 0.07%BW*Ht/°, P = 0.001). The 1st peak of the knee flexion moment also significantly increased in the toe-out gait (mean difference = 1.01%BW*Ht, P = 0.003); however, the knee flexion angle did not change significantly (initial contact: mean difference = 1.7°, P = 0.078; peak: mean difference = 1.3°, P = 0.224). SIGNIFICANCE: Toe-out gait increased the patellofemoral compressive force and dynamic knee joint stiffness because of increasing knee flexion moment, but not the knee flexion angle. When the toe-out gait is adapted, clinicians should pay attention to an increase in the patellofemoral joint loading.

Relationship Between Posterior Shoulder Tightness and Lower-Limb Flexibility in College Baseball Players.

CONTEXT: Posterior shoulder tightness evaluated as limited glenohumeral internal rotation and horizontal adduction is a risk factor for throwing-related shoulder and elbow injuries. Given that the throwing motion uses the entire body kinematics, limited lower-limb flexibility might be associated with posterior shoulder tightness. Therefore, we aimed to investigate the relationships between posterior shoulder tightness and lower-limb flexibility in college baseball players. DESIGN: Cross-sectional study. SETTING: University laboratory. PARTICIPANTS: Twenty-two college baseball players (20 right-handed and 2 left-handed). METHODS: To investigate the relationships between glenohumeral range of motion and lower-limb flexibility using simple linear regression analysis, we measured passive range of motion of glenohumeral internal rotation and horizontal adduction, hip internal/external rotation in the prone/sitting position, ankle dorsiflexion, and quadriceps and hamstrings flexibility from both shoulders and legs. RESULTS: Our analysis indicated that decreases in the lead leg hip external rotation in the prone position were moderately associated with limitations in glenohumeral internal rotation (R2 = .250, ß [95% confidence interval, CI] = 0.500 [0.149 to 1.392], P = .018) and horizontal adduction (R2 = .200, ß [95% CI] = 0.447 [0.051 to 1.499], P = .019) on the throwing shoulder. Furthermore, there were significant moderate relationships between decreases in glenohumeral internal rotation and limited lead leg quadriceps flexibility (R2 = .189, ß [95% CI] = 0.435 [0.019 to 1.137], P = .022), and between decreases in glenohumeral horizontal adduction and limited stance leg ankle dorsiflexion (R2 = .243, ß [95% CI] = 0.493 [0.139 to 1.438], P = .010). CONCLUSION: College baseball players with limited lower-limb flexibilities including the lead leg hip external rotation in the prone position, the lead leg quadriceps flexibility, and the stance leg ankle dorsiflexion showed excessive posterior shoulder tightness. The current results support the hypothesis that lower-limb flexibility is associated with posterior shoulder tightness in college baseball players.

Subsequent Jumping Increases the Knee and Hip Abduction Moment, Trunk Lateral Tilt, and Trunk Rotation Motion During Single-Leg Landing in Female Individuals.

Single-leg landings with or without subsequent jumping are frequently used to evaluate landing biomechanics. The purpose of this study was to investigate the effects of subsequent jumping on the external knee abduction moment and trunk and hip biomechanics during single-leg landing. Thirty young adult female participants performed a single-leg drop vertical jumping (SDVJ; landing with subsequent jumping) and single-leg drop landing (SDL; landing without subsequent jumping). Trunk, hip, and knee biomechanics were evaluated using a 3-dimensional motion analysis system. The peak knee abduction moment was significantly larger during SDVJ than during SDL (SDVJ 0.08 [0.10] N·m·kg-1·m-1, SDL 0.05 [0.10] N·m·kg-1·m-1, P = .002). The trunk lateral tilt and rotation angles toward the support-leg side and external hip abduction moment were significantly larger during SDVJ than during SDL (P < .05). The difference in the peak hip abduction moment between SDVJ and SDL predicted the difference in the peak knee abduction moment (P = .003, R2 = .252). Landing tasks with subsequent jumping would have advantages for evaluating trunk and hip control as well as knee abduction moment. In particular, evaluating hip abduction moment may be important because of its association with the knee abduction moment.

Improvements in asymmetry in knee flexion motion during landing are associated with the postoperative period and quadriceps strength after anterior cruciate ligament reconstruction.

This study investigated the relationship between quadriceps strength and knee kinematics during a drop vertical jump (DVJ) at 6, 9 and 12 months after anterior cruciate ligament reconstruction (ACLR) in 9 male and 22 female athletes (16.6 ± 2.1 years old). Isokinetic quadriceps strength was measured by a dynamometer (Biodex System 3). Knee flexion excursion was assessed using two-dimensional analysis. Knee flexion excursion at 6 months was significantly smaller in the involved limb than in the uninvolved limb independent of quadriceps strength (56.7° ± 9.3°, 63.4° ± 11.4°, P < 0.001). At 9 months, only the low quadriceps strength group demonstrated a similar interlimb difference (57.2°± 12.3°, 63.3° ± 10.5°, P < 0.001). At 12 months, there was no significant interlimb difference in knee flexion excursion regardless of quadriceps strength. These findings indicate that restoration in symmetrical knee flexion excursion during a DVJ requires rehabilitation as well as quadriceps strength.

Warm-Up Intensity and Time-Course Effects on Jump Height under Cold Conditions.

With this study, we aimed to investigate the effects of different warm-up intensities on counter-movement jump (CMJ) performance over time under cold conditions. Eleven male collegiate athletes volunteered. The participants performed high-intensity warm-up (HWU) at 80% VO2max and moderate-intensity warm-up (MWU) at 60% VO2max for 15 min on a bicycle ergometer in a laboratory room at 10 °C. CMJ height, vastus lateralis muscle temperature, heart rate, and perceived fatigue were measured before warm-up (Pre), immediately after (Post 0), 10 min after (Post 10), and 20 min after (Post 20). Significant main effects and interactions were found for CMJ height (time, p < 0.001 and ηp2 = 0.859; interaction, p = 0.007 and ηp2 = 0.327). HWU significantly increased CMJ height at Post 0 to Post 20 compared to that at Pre (p < 0.01), whereas MWU increased CMJ height at Post 0 only compared to that at Pre (p < 0.001). The results indicate that HWU achieved an increase in CMJ height for 20 min. MWU changed CMJ height instantly, but the change did not last compared to HWU in a cold environment.

Sex difference in frontal plane hip moment in response to lateral trunk obliquity during single-leg landing.

BACKGROUND: Lateral trunk obliquity during landing is a characteristic of anterior cruciate ligament (ACL) injuries in female athletes and affects their knee and hip kinetics and kinematics. However, it is unclear whether these effects differ between females and males. The purpose of this study was to compare the effects of lateral trunk obliquity on knee and hip kinetics and kinematics in females and males during single-leg landing. METHODS: Eighteen female (aged 22.1 ± 1.5 years) and 18 male participants (aged 21.8 ± 1.1 years) performed single-leg landings under two conditions: (1) without any instructions about trunk position (natural) and (2) with leaning their trunks laterally 15° from the vertical line (trunk obliquity). The kinetics and kinematics of their hip and knee were analyzed using a three-dimensional motion analysis with a force plate. Two-way repeated-measures ANOVA (sex × trunk obliquity) and Bonferroni pairwise comparisons were conducted. RESULTS: The trunk obliquity angle at initial contact was significantly greater in the trunk-obliquity landing condition than in the natural landing condition (natural 4.0 ± 2.2°, trunk-obliquity 15.1 ± 3.6°, P < 0.001) with no sex difference (95% CI - 1.2 to 2.2°, P = 0.555). The peak knee abduction moment was significantly larger in the trunk-obliquity landing condition than in the natural landing condition (trunk-obliquity, 0.09 ± 0.07 Nm/kg/m; natural, 0.04 ± 0.06 Nm/kg/m; P < 0.001), though there was no sex or interaction effect. A significant interaction between sex and landing condition was found for the peak hip abduction moment (P = 0.021). Males showed a significantly larger peak hip abduction moment in the trunk-obliquity landing condition than in the natural landing condition (95% CI 0.05 to 0.13 Nm/kg/m, P < 0.001), while females showed no difference in the peak hip abduction moment between the two landing conditions (95% CI - 0.02 to 0.06 Nm/kg/m, P = 0.355). CONCLUSIONS: The knee abduction moment increased with a laterally inclined trunk for both female and male participants, while the hip abduction moment increased in males but not in females. It may be beneficial for females to focus on frontal plane hip joint control under lateral trunk-obliquity conditions during single-leg landing.

Supraspinatus tendon thickness and subacromial impingement characteristics in younger and older adults.

BACKGROUND: Subacromial impingement (SAI) may be a cause of age-related rotator cuff abnormalities; therefore, the purpose of this study was to compare SAI characteristics between younger and older adults. In addition to the fact that thickened supraspinatus tendon (SST) indicates tendon abnormalities, SAI characteristics have been recognized as follows: greater SST thickness, reduced acromiohumeral distance (AHD), greater reduction of AHD (∆AHD) with arm elevation, and a higher percentage of SST within AHD (i.e., occupation ratio: OcAHD). Furthermore, we investigated the relationships between SST thickness and AHD, as well as SST thickness and ∆AHD to clarify the effect of SAI on rotator cuff abnormalities. METHODS: Healthy younger (n = 18, 21-24-year-old) and older (n = 27, 45-80-year-old) adults without any shoulder symptoms participated in this study. We measured their SST thickness and AHD at rest and at arm elevation (30° and 60°) in the scapular plane using ultrasound, and calculated ∆AHD as the relative change expressed as a percentage of the baseline. OcAHD was expressed as the ratio of SST thickness at rest to AHD at rest and in elevated positions. RESULTS: The older subjects had approximately one mm thicker SST (P = 0.003, 95% Confidence interval [CI] = 0.410 to 1.895) and approximately 1.0 to 1.3 mm greater AHD than the younger subjects (P = 0.011, 95%CI = 0.284 to 2.068 at rest; P = 0.037, 95%CI = 0.082 to 2.609 for 30° of arm elevation; P = 0.032, 95%CI = 0.120 to 2.458 for 60° of arm elevation). However, there were no differences in ΔAHD and OcAHD between the groups. CONCLUSION: This study demonstrated that, compared with the younger subjects, the older subjects showed thicker supraspinatus tendon but no other SAI characteristics including decreases in AHD and increases in OcAHD. Thus, this study suggests that older subjects showed age-related SST abnormalities without SAI, although the magnitude of the differences in SST thickness is notably small and the clinical significance of this difference is unclear.

Changes in postural control strategy during quiet standing in individuals with knee osteoarthritis.

BACKGROUND: Knee osteoarthritis (OA) impairs postural control and may affect how the lower limb joints are used for postural control. OBJECTIVE: To investigate how individuals with knee OA use lower limb joints for static postural control. METHODS: Ten patients with knee OA and thirteen healthy controls performed quiet standing for 30 s. The standard deviation of the center of mass (COM) and lower limb joint motions in the anterior-posterior (AP) and medial-lateral (ML) planes were calculated from three-dimensional marker trajectories. Pearson's correlation analysis and independent t-tests were conducted to investigate the relationship between COM and lower limb joint motion and to compare group difference, respectively. RESULTS: The AP hip angular velocity alone in the knee OA group and the AP hip and knee angular velocity in the control group were significantly correlated with the AP COM velocity. The ML hip angular velocity was significantly correlated with the ML COM velocity in both groups. The knee OA group exhibited a significantly larger standard deviation of AP COM velocity than the control group. CONCLUSIONS: Individuals with knee OA depended solely on the contribution of the hip to the AP COM velocity, which could not be successfully controlled by the knee.

Supraspinatus Tendon Changes and Glenohumeral Range of Motion in College Baseball Players.

Baseball players commonly show altered glenohumeral range of motion during internal rotation, external rotation, total rotation, and horizontal adduction. These altered ranges of motion appear to be associated with throwing shoulder injuries, which frequently involve the supraspinatus tendons; thus, we aimed to examine the relationship between altered glenohumeral range of motion and supraspinatus tendon changes in collegiate baseball players. To investigate this association using the Pearson correlation coefficient, we measured glenohumeral internal rotation, external rotation, total rotation, and horizontal adduction ranges of motion and supraspinatus tendon thickness in 22 college baseball players. Consequently, there was a significant relationship between increase in supraspinatus tendon thickness and greater deficit of internal rotation (r=-0.520, P=0.013). Increased supraspinatus tendon thickness tended to be associated with greater external rotation gain (r=0.394, P=0.073). No other range of motion had any relationship with supraspinatus tendon changes. These results might indicate that restricted glenohumeral internal rotation and excessive gain in external rotation increase the risk of supraspinatus tendon abnormalities in baseball players.

Torque-angle curve of the knee flexors in athletes with a prior history of hamstring strain.

OBJECTIVES: To investigate the knee flexor torque-angle curve after hamstring strain injury using different muscle action types and angular velocities. DESIGN: Cross-sectional. SETTING: Controlled laboratory. PARTICIPANTS: Thirteen collegiate athletes injured hamstring strain (21.0 ± 0.8 years; 173.9 ± 6.5 cm; 70.1 ± 10.5 kg). MAIN OUTCOME MEASURES: Concentric and eccentric knee flexor torque was measured at 60 & 300°/sec. Peak torque and average torque every 10° were determined from torque-angle curve and injured side was compared with non-injured side. RESULTS: No significant differences were found in the concentric muscle actions. However, the eccentric peak torque was significantly lower on the injured side at 60°/sec (p = 0.048) and at 300°/sec (p = 0.002). The average eccentric torque was significantly lower on the injured side at 60°/sec from 10° to 20° of knee flexion (p = 0.012-0.018) and at 300°/sec from 10° to 60° of knee flexion (p = 0.005-0.049). CONCLUSION: The knee flexor torque-angle curve changes with eccentric muscle action after hamstring injury. Eccentric torque declines were close to full knee extension at 60°/sec and a wide range of knee flexion at 300°/sec. The assessment and rehabilitation of eccentric hamstring strength may be important to consider the effect of the angular velocity after hamstring strain injury.

Dynamic postural control correlates with activities of daily living and quality of life in patients with knee osteoarthritis.

BACKGROUND: Knee osteoarthritis (OA) negatively affects dynamic postural control, which is a basic function that individuals use to perform activities of daily living (ADL). The purpose of this study was to investigate the associations of center of pressure (COP) control during the transition from double-leg to single-leg standing with subjective assessments of ADL and quality of life (QOL) in patients with knee OA. METHODS: Thirty-six patients (29 females) with moderate-to-severe knee OA participated. Dynamic postural control was evaluated during the transition from double-leg to single-leg standing. Each patient stood on a force plate, lifted the less affected limb as fast as possible, and maintained single-leg standing with the more affected limb. The COP movements corresponding to anticipatory postural adjustment (APA) and transitional phases were assessed. The maximum displacement and peak velocity of the COP movements in the medial-lateral direction were calculated. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was used for the subjective assessment of ADL and QOL. Pearson's product correlation analysis was performed to investigate the associations of COP movements in the APA and transitional phases with KOOS-ADL and KOOS-QOL. RESULTS: In the APA phase, the maximum COP displacement was significantly correlated with KOOS-ADL (r = -0.353, P = 0.035) and KOOS-QOL (r = -0.379, P = 0.023). In the transitional phase, the maximum COP displacement and peak COP velocity were significantly correlated with KOOS-ADL (maximum displacement: r = 0.352, P = 0.035; peak velocity: r = 0.438, P = 0.008) and with KOOS-QOL (maximum displacement: r = 0.357, P = 0.032; peak velocity: r = 0.343, P = 0.040). CONCLUSIONS: The present study showed that smaller COP movements in the APA phase and smaller and slower COP movements in the transitional phase correlated with poorer ADL and QOL conditions in patients with knee OA. These findings suggest that poor dynamic postural control is associated with poor ADL and QOL conditions in patients with moderate-to-severe medial knee OA. Conservative treatment for patients with knee OA may need to focus on dynamic postural control during the transition from double-leg to single-leg standing.

Larger hip external rotation motion is associated with larger knee abduction and internal rotation motions during a drop vertical jump.

Associations among hip motions, knee abduction and internal rotation motion during a drop vertical jump (DVJ), which increases the risk of anterior cruciate ligament injury, remain unclear. The purpose of this study was to examine associations among knee abduction, internal rotation and hip joint motions during a DVJ. Fifty-seven young female participants performed a DVJ from a 30-cm height. Hip and knee kinematics and kinetics were analysed using a three-dimensional motion analysis system and force plates. Multiple regression analysis showed that peak knee abduction angle was negatively associated with knee internal rotation and hip internal rotation excursions from initial contact (IC) to peak knee flexion, and positively associated with peak knee abduction moment (R2 = 0.465, P< 0.001). Peak knee internal rotation angle was negatively associated with the hip flexion excursion from IC to peak knee flexion and peak hip adduction moment (R2 = 0.194, P= 0.001). In addition, hip internal rotation excursion was negatively associated with knee abduction and internal rotation excursion from IC to 50 ms after IC. To avoid a large knee abduction and internal rotation motion during jump-landing training, it might be beneficial to provide landing instructions to avoid a large hip external rotation motion.

Influence of Constant Torque Stretching at Different Stretching Intensities on Flexibility and Mechanical Properties of Plantar Flexors.

ABSTRACT: Oba, K, Samukawa, M, Nakamura, K, Mikami, K, Suzumori, Y, Ishida, Y, Keeler, N, Saitoh, H, Yamanaka, M, and Tohyama, H. Influence of constant torque stretching at different stretching intensities on flexibility and mechanical properties of plantar flexors. J Strength Cond Res 35(3): 709-714, 2021-The purpose of this study was to examine the effects of constant torque stretching (CTS) at different stretching intensities on the maximal range of motion (ROM) and muscle-tendon unit (MTU) stiffness of plantar flexors. Fourteen healthy men performed 4 trials of differing stretch intensities: no stretching (control), 50, 75, and 100%. Stretch intensity was defined as maximum passive resistive torque predetermined at a familiarization trial. Each stretch trial consisted of 5 sets of 60-second CTS at the designated stretch intensity. Both maximal ROM and passive resistive torque were assessed during passive dorsiflexion, and MTU stiffness was calculated using the torque-angle curves measured before and after CTS. There were no significant differences in maximal ROM or MTU stiffness at the baseline condition. After the intervention, significantly greater maximal ROM and significantly lower MTU stiffness were observed in the 100% CTS condition than the control condition, whereas there were no significant differences between the submaximal intensity condition (i.e., 50 or 75% intensity) and the control condition. Therefore, our findings suggest that maximal intensity stretching is the most effective approach for improving both flexibility and MTU stiffness with CTS.

Postural Stability and Muscle Activation Onset during Double- to Single-Leg Stance Transition in Flat-Footed Individuals.

The effects of foot posture on postural stability and on muscular activation pattern for postural control remain unclear. This study aimed to investigate postural stability and muscular activation onset during the transition task from double- to single-leg stance in individuals with different foot postures. Twenty-seven healthy men (age: 21.5 ± 1.5 years) were divided into 3 groups using the Foot Posture Index: neutral foot (n = 10); flatfoot (n = 8); and high-arched foot (n = 9). Center of pressure (COP) data and muscle activation onset times of the tibialis anterior, peroneus longus, gastrocnemius medialis, and soleus during the transition task with eyes closed were compared among groups using one-way analysis of variance and a post-hoc Tukey honestly significant difference test (p < 0.05) when the data were normally distributed and the Kruskal-Wallis test and a post-hoc Mann-Whitney U-test with Bonferroni correction (p < 0.0167) when the data were not normally distributed. The COP displacements in the mediolateral and anteroposterior directions and the resultant COP displacement during the first 3 s after a stability time point, as determined by sequential estimation during the single-leg stance phase, differed significantly among the three groups (p < 0.05). Post-hoc tests showed that the displacements were significantly greater in the flatfoot group than in the neutral and high-arched foot groups (p < 0.05), and the effect sizes for these results were large. No muscular activation onset times showed significant intergroup differences. Postural stability was significantly decreased only in the flatfoot group, while muscle activation onsets did not differ significantly by foot posture during the transition task. Decreased postural stability may be one mechanism underlying the link between flatfoot and risk of lower limb injury, and foot posture represents a potential confounder for measuring postural stability during the transition task.

Warm-Up Intensity and Time Course Effects on Jump Performance.

Jump performance is affected by warm-up intensity and body temperature, but the time course effects have not been thoroughly investigated. The purpose of this study was to investigate time course effects on jump performance after warm-up at different intensities. Nine male athletes (age: 20.9 ± 1.0 years; height: 1.75 ± 0.03 m; weight: 66.4 ± 6.3 kg; mean ± SD) volunteered for this study. The participants performed three warm-ups at different intensities: 15 min at 80% VO2 max, 15 min at 60% VO2 max, and no warm-up (control). After each warm-up, counter movement jump (CMJ) height, vastus lateralis temperature, heart rate and subjective fatigue level were measured at three intervals: immediately after warm-up, 10 min after, and 20 min after, respectively. Significant main effects and interactions were found for muscle temperature (intensity: p < 0.01, η2p = 0.909; time: p < 0.01, η2p = 0.898; interaction: p < 0.01, η2p = 0.917). There was a significant increase of muscle temperature from the baseline after warm-up, which lasted for 20 min after warm-up with 80% VO2 max and 60% VO2 max (p < 0.01). Muscle temperature was significantly higher with warm-up at 80% VO2 max than other conditions (P < 0.01). Significant main effects and interactions for CMJ height were found (intensity: p < 0.01, η2p = 0.762; time: p < 0.01, η2p = 0.810; interaction: p < 0.01, η2p = 0.696). Compared with the control conditions, CMJ height after 80% VO2 max and 60% VO2 max warm-ups were significantly higher (p < 0.01 and p < 0.05, respectively). CMJ height at 20 min after warm-up was significantly higher for 80% VO2 max warm-up than for 60% VO2 max warm-up (p < 0.01). However, CMJ height at 10 min after 60% VO2 max warm-up was not significantly different from the baseline (p < 0.05). These results showed that both high and moderate intensity warm-up can maintain an increase in muscle temperature for 20 min. Jump performance after high-intensity warm-up was increased for 20 min compared to a moderate intensity warm-up.

Landing instructions focused on pelvic and trunk lateral tilt decrease the knee abduction moment during a single-leg drop vertical jump.

OBJECTIVES: To investigate the effects of pelvic and trunk lateral tilt-focused landing instructions on the knee abduction moment during the single-leg drop vertical jump task. DESIGN: Descriptive laboratory study. SETTING: Motion analysis laboratory. PARTICIPANTS: Fifteen young, healthy female participants. MAIN OUTCOME MEASURES: The participants performed 15 single-leg drop vertical jumps. Landing instructions with self-video recordings were provided so that the participants' pelvis and trunk remained horizontal in the frontal plane. Pelvic, trunk and knee kinematics and kinetics were evaluated using a three-dimensional motion analysis system before and after the landing instructions. RESULTS: The peak knee abduction moment significantly decreased postinstruction (preinstruction 22.6 ± 15.3 Nm, postinstruction 17.9 ± 15.4 Nm, P = 0.004), as did pelvic and trunk lateral tilt (P < 0.01). The knee abduction and internal rotation angles at initial contact significantly decreased postinstruction (P = 0.037, P = 0.007), with no significant change in the peak knee abduction and internal rotation angles from pre-to postinstruction. CONCLUSIONS: Landing instructions focused on pelvic and trunk lateral tilt are effective in decreasing the knee abduction moment during the single-leg drop vertical jump. Pelvic and trunk lateral tilt should be controlled to decrease the knee abduction moment during single-leg landing.

Prevalence and characteristics of chronic ankle instability and copers identified by the criteria for research and clinical practice in collegiate athletes.

OBJECTIVES: To investigate the prevalence and characteristics of chronic ankle instability (CAI) and copers among collegiate athletes as identified by criteria for research (CAI-R and copers-R) and for clinical practice (CAI-C and copers-C). DESIGN: Cross-sectional study. SETTING: University. PARTICIPANTS: Collegiate athletes (n = 507). MAIN OUTCOME MEASURES: Participants were assessed by questionnaires based on the International Ankle Consortium guidelines. The percentages of participants with CAI-R, CAI-C, copers-R and copers-C were calculated, respectively. Demographic and injury data were statistically compared between CAI-R and copers-R groups. RESULTS: The data of 470 participants was retained after exclusions. Of these, the prevalence of CAI-R (10.0%) was only half of that of CAI-C (19.8%), and that of copers-R and copers-C was about 5%. Seventy percent of unclassifiable participants had recurrent ankle sprains. CAI was most common in basketball, while copers were less prevalent in basketball, judo, rugby and gymnastics. The age at the initial injury was significantly younger in the CAI-R participants than in the copers-R. CONCLUSIONS: The type of sport and the age at the initial injury may be associated with developing CAI. The standard criteria may not capture the entire clinical CAI population, therefore, care should be taken when applying the research to clinical practice.

Rapid progression of mucinous tubular and spindle cell carcinoma of the kidney without sarcomatoid changes: A case report.

We report a case of unusually aggressive behavior of a mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney with no sarcomatoid changes. A 43-year-old man was referred to our hospital for a mass on his left kidney. Computed tomography revealed a tumor at the upper pole of the kidney and swollen lymph nodes. Left radical nephrectomy with lymph node dissection was performed and the tumor was diagnosed as MTSCC. Peritoneal dissemination was detected 4 months after the surgery. The patient received systemic treatments, which were not effective. He finally died of the disease 12 months after the surgery.

Abdominal draw-in maneuver changes neuromuscular responses to sudden release from trunk loading in patients with non-specific chronic low back pain.

BACKGROUND: Abdominal draw-in maneuver (ADIM) has been recommended to achieve appropriate trunk muscle response for patients with non-specific chronic low back pain (CLBP). However, it has remained unclear whether the intervention with ADIM could change the trunk muscle response to sudden release from loading, which is considered to contribute mechanical circumstances to low back pain. The purpose of the present study was to investigate the effects of the intervention with ADIM on electromyography (EMG) activities of trunk muscles following sudden release from loading. METHODS: Seventeen subjects with non-specific CLBP participated. Subjects resisted trunk flexion or extension loading in semi-seated position, and then the loading was suddenly released. EMG recordings of 6 trunk muscles were acquired using a wireless surface EMG system. Onset and offset times were calculated from the EMG data. The intervention with ADIM was provided for 4 weeks. The onset and offset times were compared between pre- and post-intervention with ADIM. RESULTS: At the post-intervention, the onset of trunk flexors following release from trunk flexion loading became significantly earlier than pre-intervention (P = 0.028). The offset of flexors following release from trunk extension loading of post-intervention was significantly earlier than that of pre-intervention (P = 0.001). CONCLUSIONS: We showed that the intervention with ADIM changed the EMG activity of trunk flexors in response to sudden release from loading. These results suggest a possibility that ADIM might be effective to improve the neuromuscular control of trunk flexors for the treatment of young patients with non-specific CLBP.

Effect of General Warm-Up Plus Dynamic Stretching on Endurance Running Performance in Well-Trained Male Runners.

Purpose: The purpose of this study was to compare the acute effects of general warm-up (GWU) and GWU plus dynamic stretching (GWU + DS) on endurance running performance in well-trained male runners. Method: The endurance running performances of eight well-trained long-distance male runners were assessed on a treadmill after 2 types of intervention for 5 min after running on the treadmill at a velocity equivalent to 70% maximal oxygen uptake (V̇O2max) in each athlete for 15 min. The interventions were GWU and GWU + DS. In the GWU + DS intervention, dynamic stretching was performed for ten repetitions as quickly as possible for the five muscle groups of the lower extremities. The total duration of the dynamic stretching was 3 min and 45 s. Endurance running performance was assessed at 1 min 15 s after the dynamic stretching. The endurance running performance was evaluated by the time to exhaustion (TTE) during running at a velocity equivalent to 90% [Formula: see text]O2max in each athlete. Results: The TTE (640.6 ± 220.4 s) after GWU + DS intervention was significantly (d = 1.02, p = .03) shorter than that (760.6 ± 249.1 s) after GWU intervention. Conclusions: The results demonstrated that GWU + DS intervention impaired immediate endurance performance of running at a velocity equivalent to 90% [Formula: see text]O2max in well-trained male runners compared with GWU intervention. Thus, we are not able to recommend that well-trained runners and their coaches use the protocol for GWU + DS described in this study during actual warm-ups.