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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. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lumbopelvic movement patterns during prone hip extension has been proposed as a clinical screening method for trunk muscle dysfunction in patients with chronic low back pain (CLBP). However, correlations between trunk muscle onset and pelvic kinematics have not been investigated. OBJECTIVE: To examine the correlation between trunk muscle onset and pelvic kinematics during prone hip extension in participants with CLBP. METHODS: Fifteen patients with CLBP and 15 healthy individuals participated. We evaluated the muscle activities of the lumbar multifidus, the longissimus, and the semitendinosus via electromyogram and the displacement angles of the pelvic tilt, oblique and rotation. RESULTS: The onset of the multifidus at the ipsilateral side of hip extension was significantly delayed in the patients with CLBP compared to the control group (P < 0.001). The onset of the ipsilateral multifidus in the control group was significantly correlated with increased anterior pelvic tilt angle (P = 0.019, r = 0.597), whereas no significant correlation was observed in the CLBP group (P = 0.810, r = - 0.068). CONCLUSION: The results suggest that pelvic kinematics during prone hip extension does not predict the delayed trunk muscle onset in patients with CLBP. [ABSTRACT FROM AUTHOR]

Dynamic stretching (DS) is performed as a warm-up to improve the range of motion and athletic performance. However, the effect of different amounts of DS on muscle performance remains unclear. This study investigated the effects of DS repetitions with one or four sets of 30 s on musculotendinous extensibility and muscle strength. Fourteen healthy men (23.6 ± 1.5 years) underwent DS to ankle plantar flexors for one set (fifteen repetitions) or four sets after warm-up. The maximal ankle dorsiflexion angle, musculotendinous stiffness (MTS), passive torque, peak plantarflexion torque during maximal isometric contraction, and muscle temperature were measured before and after stretching. A significant effect of time was observed on the maximal ankle dorsiflexion angle, MTS, passive torque, and muscle temperature (p < 0.001). However, no interactions or effects between the conditions were observed. After DS, the maximal ankle dorsiflexion angle and muscle temperature significantly increased (p < 0.01), while the MTS and passive torque significantly decreased (p < 0.01). The maximal muscle strength showed no significant effects or interactions (p = 0.198−0.439). These results indicated that one and four sets of DS effectively increased musculotendinous extensibility. Thus, one set of DS may have similar effects as a warm-up before four sets of DS. [ABSTRACT FROM AUTHOR]

It is well-known that multitasking impairs the performance of one or both of the concomitant ongoing tasks. Previous studies have mainly focused on how a secondary task can compromise visual or auditory information processing. However, despite dual tasking being critical to motor performance, the effects of dual-task performance on proprioceptive information processing have not been studied yet. The purpose of the present study was, therefore, to investigate whether sensorimotor task performance would be affected by the dual task and if so, in which phase of the sensorimotor task performance would this negative effect occur. The kinematic variables of passive and active knee movements elicited by the leg drop test were analyzed. Thirteen young adults participated in the study. The dual task consisted of performing serial subtractions. The results showed that the dual task increased both the reaction time to counteract passive knee–joint movements in the leg drop test and the threshold to detect those movements. The dual task did not affect the speed and time during the active knee movement and the absolute angle error between the final and the target knee angles. Furthermore, the results showed that the time to complete the sensorimotor task was prolonged in dual tasking. Our findings suggest that dual tasking reduces motor performance due to slowing down proprioceptive information processing without affecting movement execution. [ABSTRACT FROM AUTHOR]

Asymmetry in knee extensor moment during double-leg squatting was observed after anterior cruciate ligament reconstruction, even after the completion of the rehabilitation program for return to sports. The purpose of this study was to clarify the association between asymmetry in the knee extensor moment and pelvic rotation angle during double-leg squatting after anterior cruciate ligament reconstruction. Twenty-four participants performed double-leg squatting. Kinetics and kinematics during squatting were analyzed using a 3-dimensional motion analysis system with 2 force plates. The limb symmetry index of knee extensor moment was predicted by the pelvic rotation angle (R2 =.376, P =.001). In addition, the pelvic rotation and the limb symmetry index of the vertical ground reaction force independently explained the limb symmetry index of the knee extensor moment (R2 =.635, P <.001, β of pelvic rotation = −0.489, β of vertical ground reaction force = 0.524). Pelvic rotation toward the involved limb was associated with a smaller knee extensor moment in the involved limb than in the uninvolved limb. The assessment of pelvic rotation would be useful for partially predicting asymmetry in the knee extensor moment during double-leg squatting. Minimizing pelvic rotation may improve the asymmetry in the knee extensor moment during double-leg squatting after anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

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 (V?O[subscript 2]max) 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% V?O[subscript 2]max in each athlete. Results: The TTE (640.6 ± 220.4 s) after GWU + DS intervention was significantly (d = 1.02, p = 0.03) 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% V?O[subscript 2]max 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.

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. [ABSTRACT FROM AUTHOR]

Core exercises on an unstable surface increase trunk muscle activity, especially for local muscle groups. Therefore, there is a possibility that exercises on an unstable surface would be effective in the rehabilitation of non-specific chronic low back pain (NSCLBP). The present study assessed trunk muscle activities during bridge exercise on the floor and two kinds of unstable surfaces, i.e., a balance ball and the BOSU, for individuals with and without NSCLBP. This study enrolled 17 and 18 young participants with and without NSCLBP, respectively. In the balance ball condition, both groups showed a significant increase in erector spinae activity compared to the floor condition, and the increase in activity was significantly greater in the NSCLBP group than in the control group (p = 0.038). On the other hand, neither group showed significant changes in trunk muscle activities in the BOSU condition compared to those in the floor condition. The control group showed a significant increase in internal oblique/transversus abdominis activity under the balance ball condition (p = 0.020), whereas there were no significant changes in these muscle activities between the balance ball and floor conditions in the NSCLBP group. The present study showed that participants with NSCLBP significantly increased muscle activity of the erector spinae, one of the global back muscles, on the balance ball in spite of small effects on muscle activity of the internal oblique/transversus abdominis, which is one of the local abdominal muscles. Therefore, attention should be paid to the application of bridge exercises on the balance ball for individuals with NSCLBP. [ABSTRACT FROM AUTHOR]

Objective: To summarize the effects of physical therapist–led interventions based on the biopsychosocial (BPS) model in spinal disorders compared to interventions with no BPS model through a systematic review and meta‐analysis of randomized‐controlled trials. Type: Systematic review and meta‐analysis. Literature Survey: We searched the Web of Science, CENTRAL, MEDLINE, PsycINFO, CINAHL, and PEDro up to October 27, 2022. Methodology: Pain intensity and disability were primary outcomes and psychological factors were secondary outcomes in spinal disorders. The included intervention was physical therapist–led interventions based on the BPS model. The control group received no physiotherapy intervention for BPS. Pooled effects were analyzed as standardized mean differences (SMDs) and 95% confidence intervals (CIs), and the random‐effects model was used for the meta‐analysis. The subgroup analysis was divided into low back pain group and neck pain group. Another subgroup analysis was conducted only of the groups that had received training of the BPS model. Synthesis: Fifty‐seven studies with 5471 participants met the inclusion criteria. For pain intensity, there was a statistically significant effect for the BPS model led by physical therapists in the short, medium, and long terms. The SMDs with 95% CIs were −0.44 (−0.62, −0.27), −0.24 (−0.37, −0.12), and −0.17 (−0.28, −0.06), respectively. Outcomes were clinically significant, except in the long term. For disability, there was a statistically significant effect in the short, medium, and long terms. The SMDs with 95% CIs were −0.48 (−0.69, −0.27), −0.44 (−0.64, −0.25), and −0.37 (−0.58, −0.15), respectively. All periods were clinically significant. The quality of the evidence was low for all of the main outcomes for all of the terms. Conclusion: Physical therapist–led interventions based on the BPS model effectively improve pain intensity and disability in patients with spinal disorders based on low‐quality evidence. [ABSTRACT FROM AUTHOR]

Purpose: Jump‐landing exercises are often performed during the rehabilitation of Achilles tendon (AT) injuries. However, the factors that affect the AT force (ATF) during landing are unclear. This study aimed to determine the kinematics and ground reaction force (GRF) variables associated with the peak ATF during a drop vertical jump (DVJ). Methods: The landing phase of DVJ was evaluated in 101 healthy participants (46 males, age: 21.2 ± 1.4 years old) using a three‐dimensional motion analysis system with two force plates. ATF was estimated from the ankle flexion angle and moment. Univariate and multivariate regression analyses were performed with the peak ATF as the dependent variable. The vertical GRF (VGRF), center of pressure (COP), forward trunk leaning, hip/knee/ankle joint angles at peak ATF, and sex were used as independent variables. Results: In the univariate regression analysis, larger VGRF (β = 0.813), more anterior COP position (β = 0.214), smaller knee flexion (β = −0.251) and adduction (β = −0.252), smaller hip flexion (β = −0.407), smaller forward trunk lean (β = −0.492), and male sex (β = −0.282) were significantly associated with a larger peak ATF. Multivariate analysis revealed that larger VGRF (β = 1.018), more anterior COP position (β = 0.320), a larger knee (β = 0.442), and smaller hip flexion (β = −0.205) were associated with the larger peak ATF. Conclusions: The VGRF, COP position, and knee and hip flexion were independently associated with ATF. Modifying these factors may be useful in managing tendon loading during jump‐landing exercises. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine how the application of static stretching to ankle plantar flexors affects postural control during maximum forward leaning. Twenty-six volunteer males (age 21.4 ± 1.2 years) were randomly assigned to stretching and control conditions. Participants conducted 5-min stretching on a stretch board for the stretching condition and were kept standing for 6-min for the control condition. Before and after intervention, the range of motion (ROM) at ankle dorsiflexion and the center of pressure (COP) excursion during maximal forward leaning were determined. Mean anteroposterior COP position, COP velocity and COP areas were calculated to compare the change in postural control. After stretching, ROM was significantly increased. During maximal forward leaning after stretching, both COP position and velocity showed significant increases compared to before stretching. Moreover, COP position and velocity in the stretching condition were significantly higher than in the control condition after stretching. No significant differences were found in COP area before and after stretching. Five-minute stretching increased not only ROM but also the anterior limit of stability while maintaining posture and led to faster COP shift than before stretching. These results indicate that static stretching would improve dynamic postural control as well. [ABSTRACT FROM AUTHOR]