The Effects of Minimalist Shoes on Plantar Intrinsic Foot Muscle Size and Strength: A Systematic Review.

Minimalist shoes are proposed to prevent injury and enhance performance by strengthening intrinsic foot muscles, yet there is little consensus on the effectiveness of minimalist shoes in increasing muscle strength or size. This systematic review assesses using minimalist shoes as an intervention on changes in plantar intrinsic foot muscle size and strength. PubMed, CINHAL, Scopus, and SPORT Discus were systematically searched for articles from January 2000 to March 2022. Studies were included if they had an intervention of at least 2 weeks with a control group and examined the effect of minimalist shoes on plantar intrinsic foot strength or size (either volume, cross-sectional area, or thickness). Nine studies were included. There were significant increases and percent changes in foot muscle strength, volume, cross-sectional area, and thickness. Strength increased between 9-57%, and size increased between 7.05-10.6%. Minimalist shoes may effectively increase intrinsic foot muscle size and strength in healthy individuals, and they may also be more convenient than implementing time-intensive physical therapy programs. Future research is needed to explore using minimalist shoes as an intervention in clinical populations who would benefit from increased IFM strength and function. It will also be vital to improve upon IFM assessment methods.

Differences in Gluteal and Quadriceps Muscle Activation During Weight-Bearing Exercises Between Female Subjects With and Without Patellofemoral Pain.

ABSTRACT: Glaviano, NR and Saliba, S. Differences in gluteal and quadriceps muscle activation during weight-bearing exercises between female subjects with and without patellofemoral pain. J Strength Cond Res 36(1): 55-62, 2022-Therapeutic exercises targeting gluteal and quadriceps muscles have been previously investigated; however, these studies have only been conducted on healthy individuals. Female subjects with patellofemoral pain (PFP) present with weakness in their gluteal and quadriceps muscles and commonly perform exercises that target these muscles. Therefore, the purpose of this study was to compare lower extremity muscle activity during 5 weight-bearing exercises between female subjects with and without PFP. Twenty female subjects with PFP and 20 healthy female subjects completed 5 weight-bearing tasks: a single-leg squat (SLS), lateral step-down, step-up task, step-down task, and lunge. Surface electromyography of the gluteus medius (GMed), gluteus maximus (GMax), vastus lateralis (VL), and vastus medialis oblique (VMO) were collected. Electromyography activity were normalized to maximal voluntary isometric contractions to represent each gluteal and quadriceps muscle as a percentage. Female subjects with PFP completed a SLS and step-up tasks with less GMed and GMax activity (p < 0.05) compared with those without PFP. Female subjects with PFP also had greater VMO activity (p < 0.05) during the step-up, step down, and lunge and VL activity (p < 0.05) during the step-up and SLS compared with healthy female subjects. Practitioners should be aware that there are differences in gluteal and quadriceps muscle activation between female subjects with and without PFP while performing weight-bearing exercises. These findings should influence both the selection of specific exercises and exercise progression when developing a treatment program that has the intended focus to address gluteal or quadriceps strength deficits in female subjects with PFP.

Feasibility of a Novel Video Game-Based Electromyography Biofeedback System in Patients With Knee Osteoarthritis.

CONTEXT: A novel virtual game system Knee Biofeedback Rehabilitation Interface for game-based home therapy (KneeBright) was developed for strength training using integrated electromyography biofeedback of the quadriceps muscle to control the game. The study aimed to compare the KneeBright and electromyography biofeedback interface among patients with knee osteoarthritis. DESIGN: Controlled before and after design. METHODS: Nineteen patients with knee osteoarthritis took part in this laboratory-based study. Exercise sessions took place on 2 separate days. During session 1, participants used a conventional electromyography biofeedback system while performing 3 sets of lower body exercises with emphasis on maximal muscle activation, endurance, and precision. During session 2, participants used the KneeBright game to match the exercise sets in the first session. For both sessions, knee extension torque during the isometric muscle activation exercises and time to voluntary additional exercise were recorded. Patient engagement was assessed using the technology acceptance model and System Usability Score questionnaires. RESULTS: The peak knee extension torque produced during the control exercise session and the KneeBright exercise session were positively correlated. Knee extension torque generated during KneeBright game exercise sessions was increased by an average of 25% compared to the control sessions (2.14 vs 1.77 N·m/kg, P = .02). The mean technology acceptance model score for the KneeBright system was 3.4/5 and the mean System Usability Score was 79, both indicating positive patient engagement. CONCLUSIONS: Patients using the KneeBright game produced greater knee torque than patients using the conventional system, had positive levels of engagement, and exercised longer with the KneeBright game.

Gait biofeedback and impairment-based rehabilitation for chronic ankle instability.

Our purpose was to analyze the effects of 4 weeks of visual gait biofeedback (GBF) and impairment-based rehabilitation on gait biomechanics and patient-reported outcomes (PROs) in individuals with chronic ankle instability (CAI). Twenty-seven individuals with CAI participated in this randomized controlled trial (14 received no biofeedback (NBF), 13 received GBF). Both groups received 8 sessions of impairment-based rehabilitation. The GBF group received visual biofeedback to reduce ankle frontal plane angle at initial contact (IC) during treadmill walking. The NBF group walked for equal time during rehabilitation but without biofeedback. Dependent variables included three-dimensional kinematics and kinetics at the ankle, knee, and hip, electromyography amplitudes of 4 lower extremity muscles (tibialis anterior, fibularis longus, medial gastrocnemius, and gluteus medius), and PROs (Foot and Ankle Ability Measure Activities of Daily Living (FAAM-ADL), FAAM-Sport, Tampa Scale of Kinesiophobia (TSK), and Global Rating of Change (GROC)). The GBF group significantly decreased ankle inversion at IC (MD:-7.3º, g = 1.6) and throughout the entire stride cycle (peak inversion: MD:-5.9º, g = 1.2). The NBF group did not have significantly altered gait biomechanics. The groups were significantly different after rehabilitation for the FAAM-ADL (GBF: 97.1 ± 2.3%, NBF: 92.0 ± 5.7%), TSK (GBF: 29.7 ± 3.7, NBF: 34.9 ± 5.8), and GROC (GBF: 5.5 ± 1.0, NBF:3.9 ± 2.0) with the GBF group showing greater improvements than the NBF group. There were no significant differences between groups for kinetics or electromyography measures. The GBF group successfully decreased ankle inversion angle and had greater improvements in PROs after intervention compared to the NBF group. Impairment-based rehabilitation combined with visual biofeedback during gait training is recommended for individuals with CAI.

The interrater reliability of dynamic leap and balance test in healthy and chronic ankle instability.

The primary aim of this study was to assess the interrater reliability of the Dynamic Leap and Balance Test (DLBT) in chronic ankle instability (CAI) and healthy groups. The secondary aim was to assess the differences in errors and time taken to complete the DLBT between the two groups for both raters and to identify cutoff scores to distinguish between patients with CAI and healthy controls. This was a controlled laboratory reliability analysis study. Fourteen healthy college-aged subjects (9 women 5 men; weight = 62.10 ± 8.03; height = 168.35 ± 6.0) and sixteen with a history of CAI (9 women, 7 men; weight = 68.01 ± 10.74; height = 172.08 ± 11.37) participated. Interrater reliability was determined by independent raters for both total time taken to complete the task and errors made. The most optimal score to discriminate between two groups was determined by receiver operator curve analysis. Total time taken and errors made were also documented for group differences as secondary analysis. A strong agreement was found between the two raters for time and errors with intraclass correlation coefficient >0.80. Significantly (P < .05) higher number of errors were made and greater time taken by the CAI subjects when compared with healthy for both raters. The most optimal score to discriminate between CAI and healthy control was 43.28s and 4 errors. Excellent interrater reliability substantiates that it can be used confidently by different clinicians for testing dynamic balance. CAI group took more time and made more errors to complete the DLBT.

Foot impairments contribute to functional limitation in individuals with ankle sprain and chronic ankle instability.

PURPOSE: To investigate the clinical measures of foot posture and morphology, multisegmented joint motion and play, strength, and dynamic balance in recreationally active young adults with and without a history of a lateral ankle sprain (LAS), copers, and chronic ankle instability (CAI). METHODS: Eighty recreationally active individuals (healthy: n = 22, coper: n = 21, LAS: n = 17, CAI: n = 20) were included. Foot posture index (FPI), morphologic measures, joint motion (weight-bearing dorsiflexion (WBDF), rearfoot dorsiflexion, plantar flexion, inversion, eversion; forefoot inversion, eversion; hallux flexion, extension), joint play (proximal and distal tibiofibular; talocrural and subtalar, forefoot; 1st tarsometatarsal and metatarsophalangeal), strength (dorsiflexion, plantar flexion, inversion, eversion, hallux flexion, lesser toe flexion), and Star Excursion Balance Test (SEBT) (anterior, posteromedial, posterolateral) were assessed. RESULTS: There were no group differences in FPI or morphological measures. LAS and CAI groups had decreased ankle dorsiflexion (p = 0.001) and greater frontal plane motion (p < 0.001), first MT plantar flexion, and sagittal excursion (p < 0.001); increased talocrural glide (p = 0.02) and internal rotation (p < 0.001) and decreased forefoot inversion joint play (p < 0.001); and decreased strength in all measures (p < 0.001) except dorsiflexion compared to healthy controls. The LAS group also demonstrated decreased distal tibiofibular (p = 0.04) and forefoot general laxity (p = 0.05) and SEBT performance (anterior: p = 0.02; posteromedial: p < 0.001; posterolateral: p < 0.001). CONCLUSION: Individuals with LAS or CAI have increased pain, impaired physiologic and accessory joint motion, ligamentous tenderness, and strength in the foot and ankle. Clinicians should assess the multiple segments of the ankle-foot complex when caring for individuals with an LAS or CAI. LEVEL OF EVIDENCE: II.

Walking Gait Mechanics and Gaze Fixation in Individuals With Chronic Ankle Instability.

CONTEXT: Many individuals who suffer a lateral ankle sprain will develop chronic ankle instability (CAI). Individuals with CAI demonstrate kinematic differences in walking gait, as well as somatosensory alterations compared with healthy individuals. However, the role of vision during walking gait in this population remains unclear. OBJECTIVE: To evaluate ankle kinematics, gaze deviations, and gaze velocity between participants with CAI and healthy controls while walking on a treadmill during 3 separate visual conditions (no target, fixed target, and moving target). DESIGN: Case-control study. SETTING: Laboratory. Patients (or Other Participants): Ten CAI participants and 10 healthy matched controls participated. MAIN OUTCOME MEASURES: Ankle sagittal and frontal plane kinematics were analyzed for the entire gait cycle. Average and standard deviation (SD) for gaze deviation and gaze velocity were calculated in the horizontal (X) and vertical (Y) planes. RESULTS: No significant differences were found between groups for either ankle kinematics or gaze variables; however, large effect sizes were found in the no target condition for average deviation of X (healthy 0.05 [0.02], CAI 0.12 [0.11]). Moderate effect sizes were identified in the no target condition for SD of Y (healthy 0.04 [0.03], CAI 0.11 [0.15]) and the moving target condition for average velocity of X (healthy 1.56 [0.73], CAI 2.27 [1.15]) and Y (healthy 1.07 [0.51], CAI 1.47 [0.52]). CONCLUSIONS: Although no significant differences were found between groups, it is possible that the role of vision in individuals with CAI may be altered with a more difficult task.

Landing Stiffness Between Individuals With and Without a History of Low Back Pain.

CONTEXT: Reduced spinal stabilization, delayed onset of muscle activation, and increased knee joint stiffness have been reported in individuals with a history of low back pain (LBP). Biomechanical adaptations resulting from LBP may increase the risk for future injury due to suboptimal loading of the lower-extremity or lumbar spine. Assessing landing mechanics in these individuals could help identify which structures might be susceptible to future injury. OBJECTIVE: To compare vertical and joint stiffness of the lower-extremity and lumbar spine between individuals with and without a previous history of LBP. DESIGN: Cross-sectional study. SETTING: Research laboratory. PARTICIPANTS: There were 45 participants (24 without a previous history of LBP-age 23 [8] y, height 169.0 [8.5] cm, mass 69.8 [13.8] kg; 21 with a previous history of LBP-age 25[9] y, height 170.0 [8.0] cm, mass 70.2 [11.8] kg). INTERVENTIONS: Single-limb landing trials on the dominant and nondominant limb from a 30-cm box. MAIN OUTCOME MEASURES: Vertical stiffness and joint stiffness of the ankle, knee, hip, and lumbar spine. RESULTS: Individuals with a previous history of LBP had lower vertical stiffness (P = .04), but not joint stiffness measures compared with those without a previous history of LBP (P > .05). Overall females had lower vertical (P = .01), ankle (P = .02), and hip stiffness (P = .04) compared with males among all participants. Males with a previous history of LBP had lower vertical stiffness compared with males without a previous history LBP (P = .01). Among all individuals without a previous history of LBP, females had lower vertical (P < .01) and ankle stiffness measures (P = .04) compared with males. CONCLUSIONS: Landing stiffness may differ among males and females and a previous history of LBP. Comparisons between individuals with and without previous LBP should be considered when assessing landing strategies, and future research should focus on how LBP impacts landing mechanics.

Improvements in Lower-Extremity Function Following a Rehabilitation Program With Patterned Electrical Neuromuscular Stimulation in Females With Patellofemoral Pain: A Randomized Controlled Trial.

CONTEXT: Patellofemoral pain (PFP) is a challenging condition, with altered kinematics and muscle activity as 2 common impairments. Single applications of patterned electrical neuromuscular stimulation (PENS) have improved both kinematics and muscle activity in females with PFP; however, the use of PENS in conjunction with a rehabilitation program has not been evaluated. OBJECTIVE: To determine the effects of a 4-week rehabilitation program with PENS on lower-extremity biomechanics and electromyography (EMG) during a single-leg squat (SLS) and a step-down task (SDT) in individuals with PFP. STUDY DESIGN: Double-blinded randomized controlled trial. SETTING: Laboratory. Patients of Other Participants: Sixteen females with PFP (age 23.3 [4.9] y, mass 66.3 [13.5] kg, height 166.1 [5.9] cm). INTERVENTION: Patients completed a 4-week supervised rehabilitation program with or without PENS. MAIN OUTCOME MEASURES: Curve analyses for lower-extremity kinematics and EMG activity (gluteus maximus, gluteus medius, vastus medialis oblique, vastus lateralis, biceps femoris, and adductor longus) were constructed by plotting group means and 90% confidence intervals throughout 100% of each task, before and after the rehabilitation program. Mean differences (MDs) and SDs were calculated where statistical differences were identified. RESULTS: No differences at baseline in lower-extremity kinematics or EMG were found between groups. Following rehabilitation, the PENS group had significant reduction in hip adduction between 29% and 47% of the SLS (MD = 4.62° [3.85°]) and between 43% and 69% of the SDT (MD = 6.55° [0.77°]). Throughout the entire SDT, there was a decrease in trunk flexion in the PENS group (MD = 10.91° [1.73°]). A significant decrease in gluteus medius activity was seen during both the SLS (MD = 2.77 [3.58]) and SDT (MD = 4.36 [5.38]), and gluteus maximus during the SLS (MD = 1.49 [1.46]). No differences were seen in the Sham group lower-extremity kinematics for either task. CONCLUSION: Rehabilitation with PENS improved kinematics in both tasks and decreased EMG activity. This suggests that rehabilitation with PENS may improve muscle function during functional tasks.

Detection of Gluteal Changes Using Ultrasound Imaging During Phases of Gait in Individuals With Medial Knee Displacement.

Context: Medial knee displacement (MKD) is a common risk factor for lower-extremity injury and is related to altered gluteal muscle activity. Ultrasound imaging (USI) is a reliable means to explore mechanical muscle activity; however, no information exists regarding USI of the gluteals during gait in an MKD population. Objective: To determine differences in USI gluteal muscle activity during gait in individuals with and without MKD. Design: Descriptive laboratory study. Setting: University research laboratory. Participants: Out of 28 participants, 14 exhibiting MKD unilaterally during a single-leg squat (19.36 [1.51] y, 169.73 [7.50] cm, and 62.01 [10.57] kg; 10 females) and 14 matched non-MKD subjects (20.29 [1.73] y, 167.24 [9.07] cm, and 67.53 [16.03] kg). Interventions: Bilateral B-mode USI of the gluteus maximus (Gmax) and gluteus medius (Gmed) muscles during quiet stance, heel strike, and a 10-second treadmill walking clip. Main Outcome Measures: Gluteal thickness measures normalized to quiet stance yielded activity ratios, and percentage of muscle thickness change was assessed between heel strike and quiet stance. Differences between groups were assessed with Cohen's d effect sizes with 95% confidence intervals. Activity ratios with 90% confidence intervals plotted on 10% intervals from 0% to 100% of gait were used to compare groups and limbs. A subsample of images was measured to determine intertester reliability. Results: USI revealed decreased Gmax and Gmed percent change at heel strike (%change = -9.57% [7.15%] and -8.76% [4.26%], respectively). The MKD limb compared with the contralateral limb exhibited decreased Gmed activity ratio at 30% of gait (MKD = 0.89 [0.056]; non-MKD = 1.01 [.052]). Intertester reliability was excellent for gluteus maximus (intraclass correlation coefficient = .987 [.014]) and Gmed (intraclass correlation coefficient = .989 [.013]) measurements. Conclusions: USI highlighted gluteal activity differences of MKD limbs during gait, which may contribute to inadequate hip stabilization during this daily repetitive task. These findings potentiate the use of USI as an intervention- or screening-based visual tool.

Quadriceps and Patient-Reported Function in ACL-Reconstructed Patients: A Principal Component Analysis.

CONTEXT: Assessment of physical function for individuals after anterior cruciate ligament reconstruction (ACL-R) is complex and warrants the use of diverse evaluation strategies. To maximize the efficiency of assessment, there is a need to identify tests that provide the most meaningful information about this population. OBJECTIVE: To investigate underlying constructs of quadriceps muscle function that uniquely describe aspects of performance in patients after ACL-R and establish clinical thresholds for measures able to classify patients with and without ACL-R. DESIGN: Cross-sectional. SETTING: Research laboratory. Patients (or Other Participants): Seventy-two patients with a primary, unilateral ACL-R (32 males and 40 females, age = 26.0 [9.3] y, time since surgery = 46.5 [58.0] mo) and 30 healthy controls (12 males and 18 females, age = 22.7 [4.6] y). INTERVENTION(S): Quadriceps function was assessed bilaterally during 1 study visit. MAIN OUTCOME MEASURES: Isokinetic strength (peak torque, total work, and average power) at 90° and 180°/s, maximal voluntary isometric contraction torque, fatigue index, central activation ratio, Hoffmann reflex, and active motor threshold. Principal component analyses were performed for the involved limb, contralateral limb, and limb symmetry. Receiver-operator characteristic curve analyses were conducted to determine the diagnostic utility of each variable. Binary logistic regression was used to predict group membership (ACL-R vs healthy). RESULTS: Three components of peripheral, central, and combined (peripheral and central) muscle function were identified, explaining 70.7% to 80.5% of variance among measures of quadriceps function. Total knee-extensor work at 90°/s (≥18.4 J/kg), active motor threshold (≥39.5%), and central activation ratio (≥94.7%) of the involved limb were strong predictors of patient status and correctly classified 83.5% of patients with ACL-R (P < .001). CONCLUSIONS: Unique constructs of peripheral, central, and combined muscle function exist in patients with ACL-R. Total knee-extensor work at 90°/s, active motor threshold, and central activation ratio consistently explained a significant portion of variance in measures of quadriceps function, demonstrated acceptable to excellent diagnostic utility, and predicted group membership with 72.8% to 83.5% accuracy.

Effect of Impairment-Based Rehabilitation on Lower Leg Muscle Volumes and Strength in Patients With Chronic Ankle Instability: A Preliminary Study.

Context: Patients with chronic ankle instability (CAI) have demonstrated atrophy of foot and ankle musculature and deficits in ankle strength. The effect of rehabilitation on muscle morphology and ankle strength has not previously been investigated in patients with CAI. Objective: Our objective was to analyze the effect of impairment-based rehabilitation on intrinsic and extrinsic foot and ankle muscle volumes and strength in patients with CAI. Design: Controlled laboratory study. Setting: Laboratory. Patients: Five young adults with CAI. Intervention: Twelve sessions of supervised impairment-based rehabilitation that included range of motion, strength, balance, and functional exercises. Main Outcome Measures: Measures of extrinsic and intrinsic foot muscle volume and ankle strength measured before and after 4 weeks of supervised rehabilitation. Novel fast-acquisition magnetic resonance imaging was used to scan from above the femoral condyles through the entire foot. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a hand-held dynamometer. Results: Rehabilitation resulted in hypertrophy of all extrinsic foot muscles except for the flexor hallucis longus and peroneals. Large improvements were seen in inversion, eversion, and plantar flexion strength following rehabilitation. Effect sizes for significant differences following rehabilitation were all large and ranged from 1.54 to 3.35. No significant differences were identified for intrinsic foot muscle volumes. Conclusion: Preliminary results suggest that impairment-based rehabilitation for CAI can induce hypertrophy of extrinsic foot and ankle musculature with corresponding increases in ankle strength.

Reliability of a novel approach for quadriceps motor point assessment.

INTRODUCTION: We studied the ability of clinicians to identify quadriceps motor points using a transcutaneous electrical stimulation unit (TENS). METHODS: Twenty-two certified athletic trainers and 1 expert-rater identified the 7 motor points of the quadriceps at 2 time-points separated by 1 week. The difference was calculated between where each participant and the expert-rater identified each motor point using an x-y coordinate system. Bland-Altman plots were used to compare differences between 2 testing sessions. RESULTS: No differences were observed between participants and the expert-rater for motor point location. The smallest variability in the limits of agreements were observed in the distal vastus medialis oblique (-1.89 to 1.86 cm) and proximal vastus lateralis (-1.61 to 2.35 cm). DISCUSSION: Our results suggest the utilization of a TENS unit may be 1 way to identify quadriceps motor points to improve electrical stimulation applications. The smallest limits of agreement were over the most common quadriceps electrical stimulation electrode positions. Muscle Nerve 57: E1-E7, 2018.

Ultrasound Assessment of the Transverse Abdominis During Functional Movement.

OBJECTIVES: The traditional activation ratio divides contracted muscle thickness by resting muscle thickness while an abdominal draw-in maneuver is performed during hook lying. Ultrasound imaging during function, such as standing or gait, or peak knee flexion in a single-leg squat allows for further visualization of muscle activity. The goal of this study was to examine activation ratio calculations for transverse abdominis function in supine versus loaded conditions to determine the most informative normalization strategy for muscle activity based on thickness values. METHODS: Transverse abdominis thickness was measured via ultrasound in 35 healthy participants under 4 different conditions. Comparisons were made between the traditional activation ratio tabletop, standing activation ratio (standing abdominal draw-in maneuver thickness/quiet standing thickness), and functional activation ratio (single-leg squat thickness/quiet standing thickness). Additionally, a cued activation ratio (single-leg squat with cued abdominal draw-in maneuver thickness/single-leg squat thickness) during the single-leg squat was obtained. Activation ratios of greater than 1.0 indicated that participants could activate the muscle during activity, and values were compared by analysis of variance. RESULTS: The participants included 23 women and 12 men with a mean age ± SD of 21.3 ± 2.7 years, mass of 66.1 ± 14.4 kg, and height of 168.5 ± 10.1 cm. Activation ratios exceeded 1.0 in 94.3% for the traditional activation ratio, 85.7% for the standing activation ratio, 82.9% for the cued activation ratio, and 82.9% for the functional activation ratio. With groups defined as tabletop activated or not, the standing, cued, and functional activation ratios were all significantly different (all P < .05). CONCLUSIONS: Normalizing muscle thickness to the corresponding functional position quiet value provides a useful functional activation ratio and may help clinicians better understand the transverse abdominis role during complex functional tasks. Assessment techniques using various formulas for activation ratios reveal that the muscle functions differently during weight bearing compared to traditional measures.

Relationship Between Lower-Extremity Strength and Subjective Function in Individuals With Patellofemoral Pain.

OBJECTIVE: Evaluate the relationship between subjective knee function and lower-extremity strength in individuals with patellofemoral pain (PFP). DESIGN: Cohort. SETTING: Laboratory. PARTICIPANTS: Participants were 30 individuals with PFP (20 females and 10 males; 76.02 [17.88] kg, 173.04 [7.58] cm, and 24.9 [7] y). MAIN OUTCOME MEASURES: Subjects completed the Activities of Daily Living Scale (ADLS) and had lower-extremity hip and knee isometric strength assessed. Strength was compared between low and high subjective functioning ADLS groups. Correlations for strength and subjective function were assessed, with a linear regression utilized to determine if strength predicted subjective function. RESULTS: Quadriceps strength was significantly greater in the high subjective function group (38.5 [13.9] percent body mass) than in the low subjective function group (27.88 [8.96] percent body mass, P = .02). Significant correlations were seen between the ADLS and all 5 lower-extremity strength measures (r = .376-.535). Quadriceps strength was a strong predictor of subjective function in those with PFP, explaining 28.6% of the total variance in the ADLS. CONCLUSIONS: Quadriceps strength was a strong predictor of subjective function when assessed by the ADLS in patients with PFP and significantly greater in those with higher subjective function. A strong relationship exists between self-reported function and lower-extremity strength, suggesting the need to evaluate and treat lower-extremity weakness.

Comparison of Thigh Muscle Strain Occurrence and Injury Patterns Between Male and Female High School Soccer Athletes.

CONTEXT: Thigh muscle strains are among the most common injuries in high school soccer for both males and females. Similar results have been reported among college soccer players, specifically for hamstring strains. In college soccer, males have a higher injury rate than women, although they share common injury characteristics. Currently, no studies exist comparing the injury rate or injury characteristics of thigh muscle strains between sexes playing high school soccer. OBJECTIVE: To compare thigh muscle strain injury rates and injury event characteristics among sexes participating in high school soccer. DESIGN: Descriptive epidemiology study. SETTING: A total of 100 nationally representative high schools that participated in the High School Sports-Related Injury Surveillance System, Reporting Information Online. PARTICIPANTS: High school soccer athletes who had a thigh muscle strain. MAIN OUTCOME MEASURES: Injury rates of thigh muscle strains were calculated between sexes. The occurrence of the following variables during a thigh muscle injury was compared between sexes: grade level, age, level of play, event type, time of practice, time of competition, basic injury mechanism, soccer activity, player position, field location, practice type, and time of season. RESULTS: Males had a lower injury rate of thigh muscle strains during competition than females (rate ratio = 0.66; 95% confidence interval, 0.47-0.93). No differences between sexes existed in the distribution of first-time or recurrent event characteristics. When combining sexes, recurrent strains (93%) occurred more frequently on the offensive side of the field than first-time strains (59%), P < .001. The majority of strains occurred among the varsity players (71%), during running activities (60%) and practices (58%). CONCLUSIONS: Males were less likely to sustain a thigh muscle strain during competitions, but no other differences existed between sexes. The events surrounding all thigh muscle strains may be described with some common properties. Consideration of these characteristics may assist in the development of preventive and rehabilitative programs as well as direct future research on thigh muscle strains among high school soccer players.

Activity monitoring in men's college soccer: a single season longitudinal study.

Performance in soccer has been characterized previously using time-motion analyses; however, it is unclear if men's college soccer shares performance characteristics with women's college or men's professional soccer. The purpose of this study was to compare proportions of matches spent walking, jogging, running, and sprinting in men's college soccer. Twenty-two male college soccer players wore global positioning system units during matches. Proportions of walking, jogging, running, high-speed running, and sprinting were calculated for each player based on time period (first half, second half, extra time) and outcome (win, loss, tie). Multivariate analyses of variance were run for each time period to compare positions. Means, 95% confidence intervals, and effect sizes were calculated for each position based on time period and match outcome. There were differences in low-speed and high-speed activities based on position, with forwards and midfielders demonstrating increased high-speed activities. Positional differences may require different physiological profiles and should be a consideration during training.

Current Trends in the Management of Lateral Ankle Sprain in the United States.

OBJECTIVE: To characterize trends in the acute management (within 30 days) after lateral ankle sprain (LAS) in the United States. DESIGN: Descriptive epidemiology study. PATIENTS: Of note, 825 718 ankle sprain patients were identified; 96.2% were patients with LAS. Seven percent had an associated fracture and were excluded from the remaining analysis. SETTING: Primary and tertiary care settings. INTERVENTIONS: We queried a database of national health insurance records for 2007 to 2011 by ICD-9 codes for patients with LAS while excluding medial and syndesmotic sprains and any LAS with an associated foot or ankle fracture. MAIN OUTCOME MEASURES: The percentage of patients to receive specific diagnostic imaging, orthopedic devices, or physical therapy treatments within 30 days of the LAS diagnosis and the associated costs. RESULTS: Over two-thirds of patients with LAS without an associated fracture received radiographs, 9% received an ankle brace, 8.1% received a walking boot, 6.5% were splinted, and 4.8% were prescribed crutches. Only 6.8% received physical therapy within 30 days of their LAS diagnosis, 94.1% of which performed therapeutic exercise, 52.3% received manual therapy, and 50.2% received modalities. The annual cost associated with physician visits, diagnostic imaging, orthopedic devices, and physical therapy was 152 million USD, 81.5% was from physician evaluations, 7.9% from physical therapy, 7.2% from diagnostic imaging, and 3.4% from orthopedic devices. CONCLUSIONS: Most patients with LAS do not receive supervised rehabilitation. The small proportion of patients with LAS to receive physical therapy get rehabilitation prescribed in accordance with clinical practice guidelines. The majority (>80%) of the LAS financial burden is associated with physician evaluations.

Surface electromyography and plantar pressure during walking in young adults with chronic ankle instability.

PURPOSE: Lateral ankle sprains are common and can manifest into chronic ankle instability (CAI) resulting in altered gait mechanics that may lead to subsequent ankle sprains. Our purpose was to simultaneously analyse muscle activation patterns and plantar pressure distribution during walking in young adults with and without CAI. METHODS: Seventeen CAI and 17 healthy subjects walked on a treadmill at 4.8 km/h. Plantar pressure measures (pressure-time integral, peak pressure, time to peak pressure, contact area, contact time) of the entire foot and nine specific foot regions and medial-lateral location of centre of pressure (COP) were measured. Surface electromyography (EMG) root mean square (RMS) amplitudes throughout the entire stride cycle and area under RMS curve for 100 ms pre-initial contact (IC) and 200 ms post-IC for anterior tibialis, peroneus longus, medial gastrocnemius, and gluteus medius were collected. RESULTS: The CAI group demonstrated a more lateral COP throughout the stance phase (P < 0.001 and Cohen's d > 0.9 for all 10 comparisons) and significantly increased peak pressure (P = 0.025) and pressure-time integral (P = 0.049) under the lateral forefoot. The CAI group had lower anterior tibialis RMS areas (P < 0.001) and significantly higher peroneus longus, medial gastrocnemius, and gluteus medius RMS areas during 100 ms pre-IC (P < 0.003). The CAI group had higher gluteus medius sEMG amplitudes during the final 50 % of stance and first 25% of swing (P < 0.05). CONCLUSIONS: The CAI group had large lateral deviations of their COP location throughout the entire stance phase and increased gluteus medius muscle activation amplitude during late stance through early swing phase. LEVEL OF EVIDENCE: III.

Immediate Effects of Therapeutic Ultrasound on Quadriceps Spinal Reflex Excitability in Patients With Knee Injury.

OBJECTIVE: To investigate the effects of nonthermal therapeutic ultrasound on quadriceps spinal reflex excitability in patients with knee joint injury. DESIGN: Double-blind, randomized controlled laboratory study with a pretest posttest design. SETTING: University laboratory. PARTICIPANTS: Recreationally active volunteers with a self-reported history of diagnosed intra-articular knee joint injury and documented quadriceps dysfunction (N=30). INTERVENTIONS: A nonthermal ultrasound, or sham, treatment was applied to the anteromedial knee. MAIN OUTCOME MEASURES: Hoffmann reflex measurements were recorded at baseline, immediately postintervention, and 20 minutes post-intervention. The peak Hoffmann reflex amplitude was normalized by the peak motor response (H/M ratio) measured from the vastus medialis using surface electromyography as an estimate of quadriceps motorneuron pool excitability. A repeated-measures analysis of variance was used for comparisons. RESULTS: A significant group-by-time interaction was observed for mean (P=.016) and change (P=.044) in H/M ratio. The ultrasound group demonstrated significantly higher mean (P=.015) and change (P=.028) in H/M ratio 20 minutes postintervention than did the sham ultrasound group. CONCLUSIONS: Quadriceps motoneuron pool excitability was facilitated 20 minutes after a nonthermal therapeutic ultrasound treatment, and not a sham treatment. These data provide supporting evidence of the contribution of peripheral receptors in modulation of the arthrogenic response in patients with persistent quadriceps dysfunction. Future research in this area should attempt to identify optimal treatment parameters and translate them to clinical outcomes.