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Lee Herrington

Context:

A valgus position of the knee on functional loading tasks has been reported to be associated with patellofemoral-joint pain. Training programs to reduce knee valgus have been shown to be effective but take time. It would appear logical to use a brace or strap to help control this knee motion to reduce symptoms.

Objective:

To assess the impact of the SERF strap on knee valgus and patellofemoral-joint pain.

Design:

Repeated measures.

Setting:

University human performance laboratory.

Participants:

12 women with patellofemoral pain (mean age 24 ± 3.2 y).

Intervention:

Application of SERF strap.

Main Outcome Measures:

Knee-valgus angle on single-leg squat and step landing and visual analog scale pain score.

Results:

The application of the SERF brace significantly reduced the pain (P < .04) and knee valgus (P < .034) during both tasks.

Conclusion:

The SERF brace brings about a significant reduction in pain during functional tasks. Although the brace brought about a significant reduction in knee valgus, this failed to exceed the smallest-detectable-difference value, so the difference is likely to be related to measurement error. The mechanism as to why this the reduction in pain occurs therefore remains unclear, as this study in line with many others failed to demonstrate meaningful changes in kinematics that could provide an obvious explanation.

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Maria K. Talarico, Robert C. Lynall, Timothy C. Mauntel, Erin B. Wasserman, Darin A. Padua and Jason P. Mihalik

Although single-leg squats are a common dynamic balance clinical assessment, little is known about the relationship between parameters that influence squat movement and postural control performance. The objective of this study was to determine the relationships between squat parameters (speed and depth) and postural control under single task and dual task. A total of 30 healthy college students performed single-leg squats under single task and dual task with Stroop. Random-intercepts generalized linear mixed models determined the effect of squat parameters on center of pressure (CoP) parameters. For each 1-cm·s−1 increase in squat speed, sway range (mediolateral: β = −0.03; anteroposterior: β = −0.05) and area (β = −0.25) decreased, whereas sway speed (mediolateral: β = 0.05; anteroposterior: β = 0.29; total: β = 0.29) increased. For each 1-cm increase in squat depth, sway range (mediolateral: β = 0.05; anteroposterior: β = 0.20) and area (β = 0.72) increased, whereas sway speed (anteroposterior: β = −0.14; total: β = −0.14) decreased. Compared with single task, the association between total and anteroposterior sway speed and squat speed was stronger under dual task. Clinicians and researchers should consider monitoring squat speed and depth when assessing dynamic balance during single-leg squats, as these parameters influence postural control, especially under dual task.

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Hae-rim Han, Chung-hwi Yi, Sung-hyun You, Heon-seock Cynn, One-bin Lim and Jae-ik Son

different SLS exercises (unilateral squat [US], unilateral wall-squat [UWS], lateral step-down [LSD], and front step-down [FSD]) in subjects with GMED weakness. Methods Study Design The study was based on a repeated-measures experimental design. GMED, TFL, and AL activities, onset time, and hip adduction

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Taija Finni and Paavo V. Komi

During dynamic activities it is difficult to assess in vivo length changes in human tendon and aponeurosis. The present study compared the outcome of two methods during unilateral squat jump and drop jump performances of four volunteers. Tendinous tissue elongation of vastus lateralis muscle was estimated using either (a) direct measurement of in vivo fascicle length change and muscletendon length estimation (kinematic method), or (b) prediction using a quadratic force function in combination with direct tendon force measurement (force method). In the kinematic method the most critical measures contributing to the 10% uncertainty were the fascicle angle and fraction of the estimated fascicle length. The force method was most sensitive to resting length, with 1% error margin. Both methods predicted the same pattern of tendinous elongation because of the monotonic force/length relationship. The magnitude of length change, however, differed considerably between both methods. Based on the force method, the changes were only 20% (absolute values) or 30% (strain values) of those obtained with the kinematic method. On average, the maximum strains were 5% with the force method and 15% with the kinematic method. This difference can be explained by the fact that the kinematic method characterizes not only the changes in tendon length but also includes aponeurosis strain along the muscle belly. In addition, the kinematic method may be affected by non-uniform distribution of fascicle length change along the length of the muscle. When applying either method for estimating the patterns of tendon and tendinous tissue length changes during human locomotion, the given methodological considerations should be acknowledged.

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Oliver Gonzalo-Skok, Julio Tous-Fajardo, Luis Suarez-Arrones, José Luis Arjol-Serrano, José Antonio Casajús and Alberto Mendez-Villanueva

Purpose:

To compare the effects of unilateral and bilateral resistance training on single-leg power output, between-limbs imbalance (BLI), bilateral deficit (BLD), change of direction (COD), and linear sprinting and jumping performance in young elite basketball players.

Methods:

Twenty-two young (U-16–U-19) male basketball players were randomly assigned either to an exclusive unilateral (UNI) (n = 11) or a bilateral (BIL) (n = 11) resistance-training group during a 6-wk period. Both groups training consisted of 3 unilateral or bilateral 90° back-squat sets. A postdetermined number of repetitions was set until power output dropped to <10% of maximum power (MP) output. In addition, both groups performed 2 sets of 5 unilateral or bilateral drop jumps and 2 sets of 5 unilateral or bilateral countermovement jumps (CMJ). Pre- and posttraining, performance was assessed by an incremental bilateral and unilateral squat-load test, a multiple-COD test (V-cut test), a 15-m-sprint test (7.5 + 7.5 m) with one 180° COD performed with both right (180° RCOD) and left (180° LCOD) legs, a 25-m-sprint test (5- and 15-m split time), and a CMJ test.

Results:

Within-group analyses showed substantial improvements in 180° RCOD, bilateral and unilateral MP, 25-m-sprint test, and CMJ in both groups. Between-groups analyses showed substantially better results in 180° LCOD, MP with right and left legs, BLI, and BLD in UNI than in BIL.

Conclusions:

Both training programs substantially improved most of the physical-fitness tests, but only UNI reduced between-limbs asymmetry and achieved greater enhancements in actions that mostly required applying force unilaterally in basketball players.

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Kieran O’Sullivan, Ellen Herbert, David Sainsbury, Karen McCreesh and Amanda Clifford

Context:

The gluteus medius (Gmed) is proposed to consist of 3 functional subdivisions (anterior, middle, and posterior). Gmed weakness and dysfunction have been implicated in numerous lower extremity disorders, including patellofemoral pain syndrome (PFPS). PFPS is a knee condition that frequently occurs in females and is associated with activities such as squatting and stair climbing. There is a lack of evidence for the role of the subdivisions of the Gmed in females with and without PFPS.

Objective:

To compare muscle activation in the 3 Gmed subdivisions during 4 weight-bearing exercises in women with and without PFPS.

Design:

Single-session, repeated-measures observational study.

Setting:

University research laboratory.

Participants:

Convenience sample of 12 women with PFPS and 12 age- and gender-matched asymptomatic controls.

Intervention:

Participants performed 4 weight-bearing exercises (wall press, pelvic drop, step-up-and-over, and unilateral squat) 3 times while surface electromyography (sEMG) activity of the Gmed segments was recorded.

Main Outcome Measures:

sEMG muscle activity for each functional subdivision of the Gmed during each weight-bearing exercise was analyzed using a mixed between–within-subjects ANOVA (post hoc Bonferroni).

Results:

No statistically significant differences in muscle activation were found between the PFPS and healthy participants (P = .97). Furthermore, there were no statistically significant differences between the exercises (P = .19) or muscle fibers (P = .36) independent of group analyzed. However, the activation of the subdivisions varied according to the exercise performed (P = .003).

Conclusions:

Similar levels of muscle activation were recorded in the Gmed subdivisions of the PFPS and healthy participants during the different exercises. This is the first study to examine all 3 Gmed subdivisions in PFPS. Future studies using larger sample sizes should also investigate onset and duration of muscle activation in all Gmed subdivisions in both healthy individuals and those with PFPS.

Open access

David M. Werner and Joaquin A. Barrios

, including unilateral squatting, lateral step-downs, and bridging, regardless of utilizing a 4-point or 2-point scoring criterion (intraclass correlation coefficient [ICC] 2,1  = .09–.51). By contrast, Monnier et al 7 found good-to-excellent interrater reliability (ICC = .56–.95) for 6 active movement

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José Pino-Ortega, Alejandro Hernández-Belmonte, Carlos D. Gómez-Carmona, Alejandro Bastida-Castillo, Javier García-Rubio and Sergio J. Ibáñez

postural control in healthy individuals . Türkiye Fiz Tip Ve Rehabil Derg . 2014 ; 60 ( 1 ): 22 – 26 . PubMed ID: 5308717 10.5152/tftrd.2014.59354 54. McCurdy K , Langford G . The relationship between maximum unilateral squat strength and balance in young adult men and women . J Sport Sci Med

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Oliver Gonzalo-Skok, Alejandro Moreno-Azze, José Luis Arjol-Serrano, Julio Tous-Fajardo and Chris Bishop

following order: single-leg horizontal jump test, triple-hop horizontal jump test, bilateral CMJ test, and unilateral CMJ test. A 10-minute standardized warm-up was performed (ie, 5-min jogging, dynamic stretching, 10 bilateral squats, core exercises, 10 unilateral squats, and 3 vertical unilateral jumps