•Normalized KFM during gait was smaller in females but only in those without obesity.•Females and individuals with obesity walked with greater KAM and knee varus velocity.•Sex and BMI may uniquely ...impact sagittal and frontal plane knee mechanics in gait.
Obesity and female sex are independent risk factors for knee osteoarthritis and also influence gait mechanics. However, the interaction between obesity and sex on gait mechanics is unclear, which may have implications for tailored gait modification strategies.
The purpose of this study was to examine the influence of obesity and sex on sagittal and frontal plane knee mechanics during gait in young adults.
Forty-eight individuals with (BMI = 33.03 ± 0.59; sex:50 % female; age:21.9 ± 2.6 years) and 48 without obesity (BMI:21.59 ± 0.25; sex:50 % female; age:22.9 ± 3.57 years) matched on age and sex completed over-ground gait assessments at a self-selected speed. Two (BMI) by two (sex) analysis of variance was used to compare knee biomechanics during the first half of stance in the sagittal (knee flexion moment KFM and excursion KFE) and frontal plane (first peak knee adduction moment KAM, knee varus velocity KVV).
We observed a BMI by sex interaction for normalized KFM (P = 0.03). Females had smaller normalized KFM compared to males (P = 0.03), but only in individuals without obesity. Males without obesity had larger normalized KFM compared to males with obesity (P = 0.01), while females did not differ between BMI groups. We observed main effects of sex and BMI group, where females exhibited greater normalized KAM (P < 0.01) and KVV (P < 0.01) compared to males, and individuals with obesity walked with greater KVV compared to those without obesity (P < 0.01). All absolute joint moments were greater in individuals with obesity (all P<0.01) and males had greater absolute KFM compared to females (P < 0.01).
We observed sex differences in gait mechanics, however, KFM differences between males and females were only evident in individuals without obesity. Further, females and individuals with obesity had a larger KAM and KVV, which may contribute to larger medial compartment joint loading.
Choe, KH, Coburn, JW, Costa, PB, and Pamukoff, DN. Hip and knee kinetics during a back-squat and deadlift. J Strength Cond Res 35(5): 1364-1371, 2021-The back-squat and deadlift are performed to ...improve hip and knee extensor function. The purpose of this study was to compare lower extremity joint kinetics (peak net joint moments NJMs and positive joint work PJW) between the back-squat and deadlift. Twenty-eight resistance-trained subjects (17 men: 23.7 ± 4.3 years, 1.76 ± 0.09 m, 78.11 ± 10.91 kg; 11 women: 23.0 ± 1.9 years, 1.66 ± 0.06 m, 65.36 ± 7.84 kg) were recruited. One repetition maximum (1RM) testing and biomechanical analyses occurred on separate days. Three-dimensional biomechanics of the back-squat and deadlift were recorded at 70 and 85% 1RM for each exercise. The deadlift demonstrated larger hip extensor NJM than the back-squat {3.59 (95% confidence interval CI: 3.30-3.88) vs. 2.98 (95% CI: 2.72-3.23) Nm·kg-1, d = 0.81, p < 0.001}. However, the back-squat had a larger knee extensor NJM compared with the deadlift (2.14 95% CI: 1.88-2.40 vs. 1.18 95% CI: 0.99-1.37 Nm·kg-1, d = 1.44 p < 0.001). More knee PJW was performed during the back-squat compared with the deadlift (1.85 95% CI: 1.60-2.09 vs. 0.46 95% CI: 0.35-0.58 J·kg-1, d = 2.10, p < 0.001). However, there was more hip PJW during the deadlift compared with the back-squat (3.22 95% CI: 2.97-3.47 vs. 2.37 95% CI: 2.21-2.54 J·kg-1, d = 1.30, p < 0.001). Larger hip extensor NJM and PJW during the deadlift suggest that individuals targeting their hip extensors may yield greater benefit from the deadlift compared with the back-squat. However, larger knee extensor NJM and PJW during the back-squat suggest that individuals targeting their knee extensor muscles may benefit from incorporating the back-squat compared with the deadlift.
Individuals with anterior cruciate ligament reconstruction (ACLR) have quadriceps dysfunction that contributes to physical disability and posttraumatic knee osteoarthritis. Quadriceps function in the ...ACLR limb is commonly evaluated relative to the contralateral uninjured limb. Bilateral quadriceps dysfunction is common in individuals with ACLR, potentially biasing these evaluations.
To compare quadriceps function between individuals with ACLR and uninjured control participants.
Cross-sectional study.
Research laboratory.
Twenty individuals with unilateral ACLR (age = 21.1 ± 1.7 years, mass = 68.3 ± 14.9 kg, time since ACLR = 50.7 ± 21.3 months; females = 14; Tegner Score = 7.1 ± 0.3; 16 patellar tendon autografts, 3 hamstrings autografts, 1 allograft) matched to 20 control participants (age = 21.2 ± 1.2 years, mass = 67.9 ± 11.3 kg; females = 14; Tegner Score = 7.1 ± 0.4) on age, sex, body mass index, and Tegner Activity Scale.
Maximal voluntary isometric knee extension was performed on an isokinetic dynamometer. Peak torque (PT), rate of torque development (RTD), electromyographic (EMG) amplitude, central activation ratio (CAR), and hamstrings EMG amplitude were assessed during maximal voluntary isometric knee extension and compared between groups using independent-samples t tests. Relationships between hamstrings co-activation and quadriceps function were assessed using Pearson correlations.
Participants with anterior cruciate ligament reconstruction displayed lesser quadriceps PT (1.86 ± 0.74 versus 2.56 ± 0.37 Nm/kg, P = .001), RTD (39.4 ± 18.7 versus 52.9 ± 16.4 Nm/s/kg, P = .03), EMG amplitude (0.25 ± 0.12 versus 0.37 ± 0.26 mV, P = .04), and CAR (83.3% ± 11.1% versus 93.7% ± 3.2%, P = .002) and greater hamstrings co-activation (27.2% ± 12.8% versus 14.3% ± 3.7%, P < .001) compared with control participants. Correlations were found between hamstrings co-activation and PT (r = -0.39, P = .007), RTD (r = -0.30, P = .03), and EMG amplitude (r = -0.30, P = .03).
Individuals with ACLR possessed deficits in PT, RTD, and CAR compared with control participants. Peak torque is the net result of all agonist and antagonist activity, and lesser PT in individuals with ACLR is partially attributable to greater hamstrings co-activation.
Chronic quadriceps dysfunction has been implicated as a contributor to knee osteoarthritis (OA) development after anterior cruciate ligament reconstruction (ACLR). This dysfunction potentially leads ...to impulsive/high-rate loading during gait, thus accelerating cartilage degradation. The purpose of this study was to examine relationships between several indices of quadriceps function and gait biomechanics linked to knee OA development in individuals with ACLR.
Gait biomechanics and quadriceps function were assessed in 39 individuals with ACLR. Indices of quadriceps function included isometric peak torque and rate of torque development (RTD), isokinetic peak torque and power, and the central activation ratio. Gait biomechanics included the peak vertical ground reaction force and loading rate, and the heel strike transient (HST) magnitude and loading rate.
Isometric peak torque was not associated with any of the gait biomechanical variables. However, greater RTD was associated with lesser peak vertical ground reaction force linear (r = -0.490, P = 0.003) and instantaneous (r = -0.352, P = 0.031) loading rates, as well as a lesser HST magnitude (r = -0.312, P = 0.049) and instantaneous loading rate (r = -0.355, P = 0.029). Greater central activation ratio was associated with greater HST instantaneous (r = 0.311, P = 0.050) and linear (r = 0.328, P = 0.033) loading rates. Isokinetic peak torque and power were not associated with any of the biomechanical variables.
Poor quadriceps function, especially RTD, is associated with gait kinetics linked to cartilage degradation in individuals with ACLR. These results highlight the likely role of chronic quadriceps dysfunction in OA development after ACLR and the need to emphasize improving quadriceps function as a primary rehabilitation goal.
To determine the immediate effects of a single session of whole-body vibration (WBV) and local muscle vibration (LMV) on quadriceps function in individuals with anterior cruciate ligament ...reconstruction (ACLR).
Singe-blind, randomized crossover trial.
Research laboratory.
Population-based sample of individuals with ACLR (N=20; mean age ± SD, 21.1±1.2y; mean mass ± SD, 68.3±14.9kg; mean time ± SD since ACLR, 50.7±21.3mo; 14 women; 16 patellar tendon autografts, 3 hamstring autografts, 1 allograft).
Participants performed isometric squats while being exposed to WBV, LMV, or no vibration (control). Interventions were delivered in a randomized order during separate visits separated by 1 week.
Quadriceps active motor threshold (AMT), motor-evoked potential (MEP) amplitude, Hoffmann reflex (H-reflex) amplitude, peak torque (PT), rate of torque development (RTD), electromyographic amplitude, and central activation ratio (CAR) were assessed before and immediately after a WBV, LMV, or control intervention.
There was an increase in CAR (+4.9%, P=.001) and electromyographic amplitude (+16.2%, P=.002), and a reduction in AMT (-3.1%, P<.001) after WBV, and an increase in CAR (+2.7%, P=.001) and a reduction in AMT (-2.9%, P<.001) after LMV. No effect was observed after WBV or LMV in H-reflex, RTD, or MEP amplitude. AMT (-3.7%, P<.001), CAR (+5.7%, P=.005), PT (+.31Nm/kg, P=.004), and electromyographic amplitude (P=.002) in the WBV condition differed from the control condition postapplication. AMT (-3.0% P=.002), CAR (+3.6%, P=.005), and PT (+.30Nm/kg, P=.002) in the LMV condition differed from the control condition postapplication. No differences were observed between WBV and LMV postapplication in any measurement.
WBV and LMV acutely improved quadriceps function and could be useful modalities for restoring quadriceps strength in individuals with knee pathologies.
Individuals with obesity have impaired gait and muscle function that may contribute to reduced mobility and increased fall risk.
(1) what is the difference in spatiotemporal gait parameters and joint ...kinetics between individuals with and without obesity; (2) what is the association between spatiotemporal gait parameters, joint kinetics, and quadriceps function?
Forty-eight young adults with obesity (BMI = 33.0 ± 4.1 kg/m2) and 48 without obesity (BMI = 21.6 ± 1.7 kg/m2) completed assessments of quadriceps function (peak torque and early/late rate of torque development (RTD)) and walking biomechanics at self-selected speed. Spatiotemporal gait parameters (stance time, double support time, double support to stance ratio, step width, step length, cadence, and gait stability ratio (GSR)) and joint kinetics (total support moment, and relative contribution from extensor moments) were compared using one-way MANOVAs. Partial correlation examined the association between the total support moment and quadriceps function, and spatiotemporal gait parameters controlling for sex and speed.
Individuals with obesity walked with longer stance (p = 0.01), longer double-limb support (p < 0.001), wider steps (p < 0.001), lower cadence (p = 0.03), and a greater absolute (p < 0.001) but lesser normalized total support moment (p = 0.03) compared with adults without obesity. In those with obesity, greater PT was associated with less double limb support (p = 0.011) and smaller double support to stance ratio (p = 0.006); greater early RTD was associated with less double limb support (r = −0.455, p = 0.0021), less stance time (r = −0.384, p = 0.008), and a smaller double support to stance ratio (r = −0.371, p = 0.011). In those without obesity, a larger total support moment was associated with longer step length (r = 0.512, p < 0.001), lesser cadence (r = −0.497, p < 0.001), and smaller GSR (−0.460, p = 0.001).
Individuals with obesity walk with altered spatiotemporal gait parameters and joint kinetics that may compromise stability. Extended periods of support may be a strategy used by individuals with obesity to increase stability during gait and accomodate insufficient quadriceps function.
•Adults with obesity walked with wider steps and longer periods of double support.•Adults with obesity had a higher absolute, but lower normalized total support moment.•Altered spatiotemporal features may be a strategy to increase stability in obesity.•Longer double support was associated with lower quadriceps early RTD.•Improving quadriceps early RTD and the total support moment may be useful to enhance stability in obesity.
To evaluate the effects of whole body vibration (WBV) and local muscle vibration (LMV) on quadriceps function after experimental knee effusion (ie, simulated pathology).
Randomized controlled trial.
...Research laboratory.
Healthy volunteers (N=43) were randomized to WBV (n=14), LMV (n=16), or control (n=13) groups.
Saline was injected into the knee to induce quadriceps arthrogenic muscle inhibition (AMI). All groups then performed isometric squats while being exposed to WBV, LMV, or no vibration (control).
Quadriceps function was assessed at baseline, immediately after effusion, and immediately and 5 minutes after each intervention (WBV, LMV, control) via voluntary peak torque (VPT) and the central activation ratio (CAR) during maximal isometric knee extension on a multifunction dynamometer.
The CAR improved in the WBV (11.4%, P=.021) and LMV (7.3%, P<.001) groups immediately postintervention, but they did not improve in the control group. Similarly, VPT increased by 16.5% (P=.021) in the WBV group and 23% (P=.078) in the LMV group immediately postintervention, but it did not increase in the control group. The magnitudes of improvements in the CAR and VPT did not differ between the WBV and LMV groups.
Quadriceps AMI is a common complication following knee pathology that produces quadriceps dysfunction and increases the risk of posttraumatic osteoarthritis. Quadriceps strengthening after knee pathology is often ineffective because of AMI. WBV and LMV improve quadriceps function equivocally after simulated knee pathology, effectively minimizing quadriceps AMI. Therefore, these stimuli may be used to enhance quadriceps strengthening, therefore improving the efficacy of rehabilitation and reducing the risk of osteoarthritis.
Abstract Background Obesity is a risk factor for knee osteoarthritis. Altered gait biomechanics are common may contribute to the development of knee osteoarthritis. Research has focused on older ...obese adults with knee osteoarthritis, and it is unclear if young obese individuals display similar aberrant biomechanics. The purpose of this study was to compare gait biomechanics between normal-weight and obese young adults. Methods 15 normal-weight (body mass index = 21.5 (1.1)) and 15 obese (body mass index = 33.5 (3.7)) young adults were recruited and categorized by body mass index. Lower extremity kinematics and kinetics were collected while participants walked at standardized (1 m/s) and self-selected speeds. Analysis of variance (group by condition) was used to compare peak vertical ground reaction force, vertical loading rate, peak internal knee extension moment, peak internal knee abduction moment, peak knee flexion angle, and knee flexion excursion between groups. Findings Gait biomechanics did not differ between groups during walking at a self-selected speed. When walking at a standardized speed, obese subjects displayed greater instantaneous vertical loading rates (46.2 vs. 35.0 N/s, P < 0.001), and lesser knee flexion excursion (5.5° vs. 7.7°, P = 0.04). Instantaneous vertical loading rate was greater during walking at a self-selected speed compared to a standardized speed in the obese ( P = 0.007) and normal weight groups ( P = 0.001). Interpretation As greater loading rates are related to cartilage degeneration, these results suggest that obesity may contribute to knee osteoarthritis. Prospective studies are needed to identify the influence of higher loading rates on knee osteoarthritis.
Abstract Purpose Vibratory stimuli enhance muscle activity and may be used for rehabilitation and performance enhancement. Efficacy of vibration varies with the frequency of stimulation, but the ...optimal frequency is unclear. The purpose of this study was to examine the effects of 30 Hz and 60 Hz local muscle vibration (LMV) on quadriceps function. Methods Twenty healthy volunteers (age = 20.4 ± 1.4 years, mass = 68.1 ± 11.0 kg, height = 170.1 ± 8.8 cm, males = 9) participated. Isometric knee extensor peak torque (PT), rate of torque development (RTD), and electromyography (EMG) of the quadriceps were assessed followed by one of the three LMV treatments (30 Hz, 60 Hz, control) applied under voluntary contraction, and again immediately, 5, 15, and 30 min post-treatment in three counterbalanced sessions. Dependent variables were analyzed using condition by time repeated-measures ANOVA. Results The condition × time interaction was significant for EMG amplitude ( p = 0.001), but not for PT ( p = 0.324) or RTD ( p = 0.425). The increase in EMG amplitude following 30 Hz LMV was significantly greater than 60 Hz LMV and control. Conclusions These findings suggest that 30 Hz LMV may elicit an improvement in quadriceps activation and could be used to treat quadriceps dysfunction resulting from knee pathologies.
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