and low-back region diminishes (eg, when one is standing on an unstable surface and implementing overhead and single-leg squats), individuals may rely more heavily on other proprioceptive inputs. 3 This process is known as proprioceptive reweighting, which leads to the greater use of the
Search Results
Eight-Week Inspiratory Muscle Training Alters Electromyography Activity of the Ankle Muscles During Overhead and Single-Leg Squats: A Randomized Controlled Trial
Behnam Gholami-Borujeni, Ali Yalfani, and Leila Ahmadnezhad
Effects of Toe Direction on Biomechanics of Trunk, Pelvis, and Lower-Extremity During Single-Leg Drop Landing
Aiko Sakurai, Kengo Harato, Yutaro Morishige, Shu Kobayashi, Yasuo Niki, and Takeo Nagura
trunk, pelvis, as well as hip and knee joints during single-leg drop landing (SLDL). It was hypothesized that different toe directions would affect biomechanics of trunk and pelvis as well as that of knee joint. Methods Participants A total of 27 male recreational-level athletes, with a mean age of 19
Single-Leg Landing Strategy after Knee-Joint Cryotherapy
Joseph M. Hart, Jamie L. Leonard, and Christopher D. Ingersoll
Context:
Despite recent findings regarding lower extremity function after cryotherapy, little is known of the neuromuscular, kinetic, and kinematic changes that might occur during functional tasks.
Objective:
To evaluate changes in ground-reaction forces, muscle activity, and knee-joint flexion during single-leg landings after 20-minute knee-joint cryotherapy.
Design:
1 × 4 repeated-measures, time-series design.
Setting:
Research laboratory.
Patients or Other Participants:
20 healthy male and female subjects.
Intervention:
Subjects performed 5 single-leg landings before, immediately after, and 15 and 30 minutes after knee-joint cryo-therapy.
Main Outcome Measures:
Ground-reaction force, knee-joint flexion, and muscle activity of the gastrocnemius, hamstrings, quadriceps, and gluteus medius.
Results:
Cryotherapy did not significantly (P > .05) change maximum knee-joint flexion, vertical ground-reaction force, or average muscle activity during a single-leg landing.
Conclusion:
Knee-joint cryotherapy might not place the lower extremity at risk for injury during landing.
Effect of Fatigue on Single-Leg Hop Landing Biomechanics
Karl F. Orishimo and Ian J. Kremenic
The objective of this study was to measure adaptations in landing strategy during single-leg hops following thigh muscle fatigue. Kinetic, kinematic, and electromyographic data were recorded as thirteen healthy male subjects performed a single-leg hop in both the unfatigued and fatigued states. To sufficiently fatigue the thigh muscles, subjects performed at least two sets of 50 step-ups. Fatigue was assessed by measuring horizontal hopping ability following the protocol. Joint motion and loading, as well as muscle activation patterns, were compared between fatigued and unfatigued conditions. Fatigue significantly increased knee motion (p = 0.012) and shifted the ankle into a more dorsiflexed position (p = 0.029). Hip flexion was also reduced following fatigue (p = 0.042). Peak extension moment tended to decrease at the knee and increase at the ankle and hip (p = 0.014). Ankle plantar flexion moment at the time of peak total support moment increased from 0.8 (N⋅m)/kg (SD, 0.6 [N⋅m]/kg) to 1.5 (N⋅m)/kg (SD, 0.8 [N⋅m]/kg) (p = 0.006). Decreased knee moment and increased knee flexion during landings following fatigue indicated that the control of knee motion was compromised despite increased activation of the vastus medialis, vastus lateralis, and rectus femoris (p = 0.014, p = 0.014, and p = 0.017, respectively). Performance at the ankle increased to compensate for weakness in the knee musculature and to maintain lower extremity stability during landing. Investigating the biomechanical adaptations that occur in healthy subjects as a result of muscle fatigue may give insight into the compensatory mechanisms and loading patterns occurring in patients with knee pathology. Changes in single-leg hop landing performance could be used to demonstrate functional improvement in patients due to training or physical therapy.
The Relationship Between 2-Dimensional Knee-Valgus Angles During Single-Leg Squat, Single-Leg-Land, and Drop-Jump Screening Tests
Allan Munro, Lee Herrington, and Paul Comfort
Context:
Injuries to the anterior cruciate ligament (ACL) and patellofemoral joint (PFJ) are a significant problem in female athletes. A number of screening tasks have been used in the literature to identify those at greatest risk of injury. To date, no study has examined the relationship in 2-dimensional (2D) knee valgus between common screening tasks to determine whether individuals exhibit similar movement patterns across tasks.
Objective:
To establish whether frontal-plane projection angle (FPPA) during the single-leg squat (SLS), single-leg land (SLL), and drop jump (DJ) are related.
Design:
Cross-sectional study.
Setting:
University laboratory.
Participants:
52 national-league female football players and 36 national-league female basketball players.
Main Outcome Measures:
2D FPPA during the SLS, SLL, and DJ screening tasks.
Results:
Significant correlations were found between tasks. FPPA in the SLS was significantly correlated with SLL (r = .52) and DJ (r = .30), whereas FPPA in the SLL was also significantly correlated to DJ (r = .33). FPPA was significantly greater in the SLS than in the SLL (P < .001) and DJ (P < .001) and in the SLL than in the DJ (P < .001).
Conclusion:
The results showed that 2D FPPA is correlated across the SLS, SLL, and DJ tasks. However, significantly greater FPPA values in the unilateral tasks suggest that the DJ may not identify risk of injury in sports where primary injury mechanisms are during unilateral loading tasks. Therefore, it is recommended that both unilateral and bilateral tasks be included when screening for ACL and PFJ injury risk.
Changes in Knee and Trunk Alignment in People With Hip Pain and Healthy Controls When Using a Decline Board During Single-Leg Squat
Matthew D. Freke, Kay Crossley, Trevor Russell, Kevin J. Sims, and Adam Semciw
Hip strength and range of movement (ROM) impairments are consistently reported in individuals with hip pain when compared with asymptomatic controls. 1 – 3 The presence of hip pain also affects lower limb reaching, gait, forward stepping, and squatting with evidence that dynamic single-leg balance
Relationship Between Bilateral Differences in Single-Leg Jumps and Asymmetry in Isokinetic Knee Strength
Yuji Kobayashi, Junjiro Kubo, Takeo Matsubayashi, Akifumi Matsuo, Kando Kobayashi, and Naokata Ishii
The aims of the study were to investigate the differences in kinematics and kinetics between the dominant and nondominant leg during single-leg jumps without arm swing, and to determine the relationship between bilateral asymmetry in isokinetic knee strength and the single-leg jump. Isokinetic knee strength and single-leg jump kinematics and kinetics were measured in 11 male participants. The bilateral asymmetry index was calculated for each parameter. For isokinetic knee strength, there were no significant differences between the dominant and nondominant legs. Significant correlations were observed for the bilateral asymmetry index for isokinetic knee strength at 180 degrees per second and the bilateral asymmetry indexes for maximum flexion angle and the mean knee joint torque during the single-leg jumps. In conclusion, the findings of the current study suggest an association between knee strength imbalances and the joint angle, as well as the torque produced in single-leg jumps, although no relationship between knee strength and jump height was observed.
Effect of Sand on Landing Knee Valgus During Single-Leg Land and Drop Jump Tasks: Possible Implications for ACL Injury Prevention and Rehabilitation
Mark C. Richardson, Andrew Wilkinson, Paul Chesterton, and William Evans
demonstrated that the knee abduction moment (KAM), a significant predictor of knee valgus 9 , 12 and subsequent ACL injury risk, was reduced on sand compared with a firm surface during a single-leg jump task. 28 However, the magnitude of the effect of sand on landing knee valgus specifically is unknown. If
Joint Torques and Patellofemoral Force During Single-Leg Assisted and Unassisted Cycling
Rodrigo R. Bini, Tiago C. Jacques, and Marco A. Vaz
Context:
Unassisted single-leg cycling should be replaced by assisted single-leg cycling, given that this last approach has potential to mimic joint kinetics and kinematics from double-leg cycling. However, there is need to test if assisting devices during pedaling effectively replicate joint forces and torque from double-leg cycling.
Objectives:
To compare double-leg, single-leg assisted, and unassisted cycling in terms of lower-limb kinetics and kinematics.
Design:
Cross-sectional crossover.
Setting:
Laboratory.
Participants:
14 healthy nonathletes.
Interventions:
Two double-leg cycling trials (240 ± 23 W) and 2 single-leg trials (120 ± 11 W) at 90 rpm were performed for 2 min using a bicycle attached to a cycle trainer. Measurements of pedal force and joint kinematics of participants’ right lower limb were performed during double- and single-leg trials. For the single-leg assisted trial, a custom-made adaptor was used to attach 10 kg of weight to the contralateral crank.
Main Outcome Measures:
Peak hip, knee, and ankle torques (flexors and extensors) along with knee-flexion angle and peak patellofemoral compressive force.
Results:
Reduced peak hip-extensor torque (10%) and increased peak knee-flexor torque (157%) were observed at the single-leg assisted cycling compared with the double-leg cycling. No differences were found for peak patellofemoral compressive force or knee-flexion angle comparing double-leg with single-leg assisted cycling. However, single-leg unassisted cycling resulted in larger peak patellofemoral compressive force (28%) and lower knee-flexion angle (3%) than double-leg cycling.
Conclusions:
These results suggest that although single-leg assisted cycling differs for joint torques, it replicates knee loads from double-leg cycling.
The Effects of Gluteal Strength and Activation on the Relationship Between Femoral Alignment and Functional Valgus Collapse During a Single-Leg Landing
Jennifer A. Hogg, Terry Ackerman, Anh-Dung Nguyen, Scott E. Ross, Randy J. Schmitz, Jos Vanrenterghem, and Sandra J. Shultz
or passive hip ROM. 17 As primary extensors, external rotators, and abductors of the hip, these muscles work eccentrically to control dynamic hip internal rotation and adduction, which are the 2 primary components of functional valgus collapse. This is particularly true in a single-leg stance when
