Effects of two pre-running training interventions on running kinematics and strength - A randomized controlled trial in novice recreational runners.

ACL Research Retreat V

The relationship between maximal hip abductor strength and resultant loading at the knee during walking.

Hip abductor strength in people with knee osteoarthritis: A cross-sectional study of reliability and association with function

Exploring the effects of a weighted vs unweighted low-dose isometric Copenhagen adduction exercise training programme on hip adduction and abduction strength: a randomised controlled trial in senior-level male amateur rugby union players.

Objective: Adductor muscle strain in ice hockey is a major problem associated with reduced hip strength. The aims of this study were to examine between-limb differences in hip adduction and abduction strength, and adduction/abduction strength ratios in male elite junior ice hockey players. Further aim was to explore whether these hip strength measures are related to a history of groin injury. Methods: Thirty-four male elite junior ice hockey players (age 17.1 ± 1.3 years) participated in the study. A hand-held dynamometer was used to assess hip adduction and abduction strength in the dominant and non-dominant limbs. The players were tested in the side-lying position with a ‘break test’. Results: No significant between-limb differences in hip adduction strength (3.2% [range -27% to 34%], P= 0.283), hip abduction strength (5.3% [range -12% to 45%], P=0.053), or hip adduction/abduction strength ratios (dominant limb 1.01 ± 0.18 and nondominant limb 1.02 ± 0.13, P = 0.727) were found. Of the 34 players, 14 reported a history of unilateral groin injury within the previous year. Players with a history of groin injury had marginally lower hip adduction and abduction strength than uninjured players, however, the differences were not statistically significant (P>0.05). Adduction/abduction ratios did not differ between players with a previous injury and uninjured players (P>0.05). Conclusion: The results showed no between-limb differences in hip adduction and abduction strength, or abnormal adduction/abduction strength ratios in currently uninjured male elite junior ice hockey players. To evaluate hip strength recovery following an injury, and to identify players at risk of sustaining an adductor strain, the contralateral limb can therefore be used as a reference. A history of unilateral groin injury within the previous year does not seem to affect hip adduction and abduction strength and strength ratios in male elite junior hockey players.

Purpose: Stress urinary incontinence (SUI) is common among females participating in high-impact sports such as running. Differences in hip biomechanics during walking gait and hip strength have been found between females who experience SUI and continent females, but this has not been studied in runners. The purpose of this study was to determine if there is a difference in hip strength, hip biomechanics, and ground reaction forces (GRFs) during running between female runners with and without SUI during running. Methods: This was a cross-sectional observational study of 45 participants ( n = 14 with SUI; n = 31 without SUI). After a warm-up period, participants ran on an instrumented treadmill for 5 minutes at a self-selected 5 K race pace. Hip adduction excursion, hip abduction moment, and peak vertical and horizontal GRF during stance were calculated. Isokinetic and isometric hip abduction strength was assessed using an isokinetic dynamometer. MANOVA analyses were used to determine any differences in hip abduction strength, hip biomechanics, and peak GRFs between female runners with and without SUI. Results: There were no significant differences in hip abduction strength ( P = .292), hip biomechanics ( P = .621), or peak GRFs ( P = .935) during running between those with and without SUI. Discussion: Continent and incontinent female runners demonstrate similar hip strength, hip biomechanics, and GRFs during running. These findings support the importance of an individualized approach beyond assessing hip strength and biomechanics to evaluating and treating patients with SUI during running.

This study investigated the changes in running mechanics and spring-mass behavior over a 24-h treadmill run (24TR). Kinematics, kinetics, and spring-mass characteristics of the running step were assessed in 10 experienced ultralong-distance runners before, every 2 h, and after a 24TR using an instrumented treadmill dynamometer. These measurements were performed at 10 km·h, and mechanical parameters were sampled at 1000 Hz for 10 consecutive steps. Contact and aerial times were determined from ground reaction force (GRF) signals and used to compute step frequency. Maximal GRF, loading rate, downward displacement of the center of mass, and leg length change during the support phase were determined and used to compute both vertical and leg stiffness. Subjects' running pattern and spring-mass behavior significantly changed over the 24TR with a 4.9% higher step frequency on average (because of a significantly 4.5% shorter contact time), a lower maximal GRF (by 4.4% on average), a 13.0% lower leg length change during contact, and an increase in both leg and vertical stiffness (+9.9% and +8.6% on average, respectively). Most of these changes were significant from the early phase of the 24TR (fourth to sixth hour of running) and could be speculated as contributing to an overall limitation of the potentially harmful consequences of such a long-duration run on subjects' musculoskeletal system. During a 24TR, the changes in running mechanics and spring-mass behavior show a clear shift toward a higher oscillating frequency and stiffness, along with lower GRF and leg length change (hence a reduced overall eccentric load) during the support phase of running.

ABSTRACTBackgroundFalls are a major public health issue, largely driven by age‐related declines in hip and lower limb muscle strength. Hip muscle strength plays a critical role in postural stability and falls prevention. Lower balance confidence increases fall risk by restricting activity participation, which may contribute to muscle weakness over time. This study examined the association between hip abductor and flexor strength and the incidence of injurious falls in older adults and investigated whether hip abductor and flexor strength mediate the relationship between balance confidence and incident injurious falls.MethodsParticipants (n = 952; aged ≥ 65 years) were drawn from the Geelong Osteoporosis Study (GOS). The outcome was the time to first emergency department presentation for an incident injurious fall. Hip abductor and flexor strength were assessed using a handheld dynamometer to measure hip abduction and flexion force, with strength values adjusted for leg lean mass measured by dual‐energy X‐ray absorptiometry. Balance confidence was assessed using the 14‐item Modified Falls Efficacy Scale (MFES). Associations between hip muscle strength and incident injurious falls were evaluated using a competing risk regression model, which accounted for death as a competing event. The results are expressed as adjusted sub‐distribution hazard ratios (aSHR) and 95% confidence intervals. Mediation analysis was conducted to assess whether hip abductor and flexor strength mediated the relationship between balance confidence and the incidence of injurious falls.ResultsAmong the 952 participants, 38% were women (mean age 76.1 ± 7.3 years), and 62% were men (mean age 76.9 ± 7.0 years). The median follow‐up time was 11.5 years (IQR 5.9–19.0). During follow‐up, 219 participants (23.0%) experienced at least one injurious fall, corresponding to an incidence rate of 19.3 per 1000 person‐years (95% CI: 16.9–22.0). Greater hip abductor strength was associated with a lower risk of incident injurious falls (aSHR = 0.835, 95% CI: 0.724–0.963; p = 0.013), with each 1‐N/kg increase in hip abductor strength reducing the sub‐distribution hazard by 16.5%. Hip flexor strength was not significantly associated with incident injurious falls. Hip abductor strength accounted for 23.7% of the association between balance confidence and incident injurious falls.ConclusionsGreater hip abductor strength is protective against incident injurious falls in older adults and partially mediates the relationship between balance confidence and injurious falls. Fall prevention strategies should integrate hip abductor strengthening with interventions targeting cognitive and psychological factors, such as improving balance confidence.

Chronic ankle instability (CAI) is associated with hip strength deficits and altered movement in the lower extremity. However, it remains unclear how hip strength deficits contribute to lateral ankle sprain (LAS) mechanisms. We aimed to compare lower extremity landing kinematics and isometric hip strength between individuals with and without CAI and examine associations between hip kinematics and strength. Seventy-six individuals completed 5 single-leg landings, during which we collected three-dimensional ankle, knee, and hip kinematics from 200 milliseconds pre-initial contact to 50 milliseconds post-initial contact. We calculated average peak torque (Nm/kg) from 3 trials of isometric hip extension, abduction, and external rotation strength testing. One-way analyses of variance assessed group differences (CAI, LAS coper, and control) in hip strength and kinematics. Pearson product moment correlations assessed associations between hip kinematics and strength. We adjusted the kinematic group comparisons and correlation analyses for multiple comparisons using the Benjamini-Hochberg method. The CAI group exhibited less hip abduction during landing than LAS copers and controls. The CAI group had lower hip external rotation strength than LAS copers (P = .04, d = 0.62 [0.05, 1.17]) and controls (P < .01, d = 0.87 [0.28, 1.43]). Effect sizes suggest that the CAI group had deficits in EXT compared with controls (d = 0.63 [0.06, 1.19]). Hip strength was not associated with hip landing kinematics for any group. Altered landing mechanics displayed by the CAI group may promote mechanisms of LAS, but they are not associated with isometric hip strength. However, hip strength deficits may negatively impact other functional tasks, and they should still be considered during rehabilitation. Level III, case-control study.

This study aimed to evaluate, in an isolated and relative manner, hip abductor (ABD) and adductor (AD) strength and to study the extent to which these factors are related to balance and ankle dorsiflexion mobility in young elite female basketball players. Sixty trainee-level elite female basketball players (13–18 years old), who voluntarily agreed to participate in the study, were divided into three subgroups based on competition age divisions (U14, U16, U18). Isometric hip ABD and AD strength in each leg was evaluated using the ForceFrame Strength Testing System, also calculating the strength ratio and imbalance between legs. Y Balance Test (YBT) and ankle dorsiflexion mobility were also assessed. ANOVA was used for between-group differences analysis. Likewise, the impact of hip strength on balance and ankle mobility was analyzed using Pearson's correlation coefficient. A linear regression model for dependent variables was created with all variables that exhibited significant correlations. A between-group comparison analysis for the three competition age subgroups (U14, U16, U18) revealed non-significant differences (p > 0.005) for the hip strength variables except for hip ABD strength. The correlation study showed low-moderate effect sizes for hip ABD (in both the contralateral and homolateral limb) and AD strength (only the homolateral limb) with YBT and ankle dorsiflexion. However, when performing a regression model, only right hip ABD significantly predicted right limb YBT scores (β = 0.592, p = 0.048). The present study indicated that, although both hip ABD and AD strength correlate with balance and ankle mobility with low-moderate effect sizes, only hip ABD strength was found to significantly predict YBT scores. Therefore, the potential role of hip ABD strength in particular, but also hip AD strength, for monitoring and enhancing balance and ankle mobility outcomes, should be taken into consideration when designing and implementing preventive strategies for lower-limb injuries.

Hip abductors, important for controlling pelvic and femoral orientation during gait, may affect knee pain. Our objective was to evaluate the relation of hip abductor strength to worsened or new-onset frequent knee pain. Given previously noted associations of knee extensor strength with osteoarthritis in women, we performed sex-specific analyses. We used data from the Multicenter Osteoarthritis study. Hip abductor and knee extensor strength was measured. Knee pain was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire and a question about frequent knee pain at baseline (144-month visit), and 8, 16, and 24 months thereafter. Knee pain outcomes were worsened knee pain (2-point increase in WOMAC pain) and incident frequent knee pain (answering yes to the frequent knee pain question among those without frequent knee pain at baseline). Leg-specific analyses tested hip abductor strength as a risk factor for worsened and new frequent knee pain, adjusting for potential covariates. Additionally, we stratified by knee extensor strength (high versus low). Among women, compared to the highest quartile of hip abductor strength, the lowest quartile had 1.7 (95% confidence interval [95% CI] 1.1-2.6) times the odds of worsened knee pain; significant associations were limited to women with high knee extensor strength (odds ratio 2.0 [95% CI 1.1-3.5]). We found no relation of abductor strength to worsening knee pain in men or with incident frequent knee pain in men or women. Hip abductor weakness was associated with worsening knee pain in women with strong knee extensors, but not with incident frequent knee pain in men or women. Knee extensor strength may be necessary, but not sufficient, to prevent pain worsening.

Total knee arthroplasty (TKA) is associated with declines in hip abductor (HA) muscle strength; however, a longitudinal analysis demonstrating the influence of TKA on trajectories of HA strength change has not been conducted. The purpose of this study was to quantify changes in HA strength from pre-TKA through 3 months post-TKA and to characterize the relationship between HA strength changes and physical performance. This study is a post hoc analysis of a randomized controlled trial. Data from 162 participants (89 women, mean age = 63 y) were used for analysis. Data were collected by masked assessors preoperatively and at 1 and 3 months following surgery. Outcomes included: Timed "Up and Go" test (TUG), Stair Climbing Test (SCT), Six-Minute Walk Test (6MWT), and walking speed. Paired t tests were used for between- and within-limb comparisons of HA strength. Multivariable regression was used to determine contributions of independent variables, HA and knee extensor strength, to the dependent variables of TUG, SCT, 6MWT, and walking speed at each time point. Hip abductor strength was significantly lower in the surgical limb pre-TKA (mean = 0.015; 95% CI = 0.010-0.020), 1 month post-TKA (0.028; 0.023-0.034), and 3 months post-TKA (0.02; 0.014-0.025) compared with the nonsurgical limb. Hip abductor strength declined from pre-TKA to 1 month post-TKA (18%), but not at the 3-month time point (0%). Hip abductor strength independently contributed to performance-based outcomes pre-TKA; however, this contribution was not observed post-TKA. The post hoc analysis prevents examining all outcomes likely to be influenced by HA strength. Surgical limb HA strength is impaired prior to TKA, and worsens following surgery. Furthermore, HA strength contributes to performance-based outcomes, supporting the hypothesis that HA strength influences functional recovery.

Frontal plane kinematics of the hip during running: Are they related to hip anatomy and strength?

Background: Balance impairment is the most common risk factor for falls among older adults, with three potential factors (tactile sensation, proprioception, and muscle strength) being responsible for their balance control. However, controversies remain on whether or not balance control is related to the three contributors among older adults. Therefore, clarifying the above questions helps explain the mechanisms of increased falls among senior older adults. This study compares the balance control and the three factors and investigates their relationships among older adults of different ages. Methods: 166 participants ultimately passed the qualification assessment and were categorized into younger (YG, 60-69years, n = 56), middle (MG, 70-79years, n = 57), or older (OG, ≥80years, n = 53) aged groups. Berg Balance Scale (BBS) performance, tactile sensation, proprioception, and muscle strength were tested. One-way ANOVA and partial correlation were performed to explore the differences between groups in BBS and its three potential contributors, along with the correlations between them within each age group. Results: Significant differences among the three groups were detected in BBS scores (p < 0.001), tactile sensation at the great toe (p = 0.015) and heel (p = 0.025), proprioception of knee flexion (p < 0.001) and extension (p < 0.001), and ankle plantarflexion (p < 0.001) and dorsiflexion (p < 0.001), and muscle strength of ankle plantarflexion (p < 0.001) and dorsiflexion (p < 0.001), and hip abduction (p < 0.001). Proprioception of knee flexion (r = -0.351, p = 0.009) and extension (r = -0.276, p = 0.041), and ankle plantarflexion (r = -0.283, p = 0.036), and muscle strength of ankle plantarflexion (r = 0.326, p = 0.015) and hip abduction (r = 0.415, p = 0.002) were correlated with BBS among the YG. Proprioception of ankle plantarflexion (r = -0.291, p = 0.030) and muscle strength of ankle plantarflexion (r = 0.448, p = 0.001) and dorsiflexion (r = 0.356, p = 0.007) were correlated with BBS among the MG. Muscle strength of ankle plantarflexion (r = 0.276, p = 0.039) and hip abduction (r = 0.324, p = 0.015) were correlated with BBS among the OG. Conclusion: YG and MG had better balance control, tactile sensation, proprioception, and muscle strength compared to OG. Proprioception correlated with balance control in YG and MG, but not in the OG. The worsen proprioception among the OG could be the key for increased falls. Exercise should be recommended to improve proprioception among senior older adults.

BackgroundLittle is known about changes in kinetics or kinematics following a 10 km training run. This information has implications on risk of running-related injury.PurposeThe purpose of this study was to examine the effect of a 10 km run on running kinematics and kinetics in a sample of experienced runners.Study DesignCross-Sectional StudySubjectsNineteen runners ages 18-48 (7 female, 12 male) consented to participate including eight (3 female, 5 male) ultra-runners, and 11 (4 female, 7 male) recreational runners.MethodsFollowing collection of demographic data and completion of a short running survey, participants did a 6-minute run at their self-selected running speed to acclimate to the instrumented treadmill. Reflective markers were placed over designated anatomical landmarks on both sides of the pelvis as well as the left lower extremity and marked with a skin pen. Subjects then ran on the treadmill and 30 seconds of video data were recorded at 240 frames/sec using a high-speed camera for the sagittal plane and the frontal plane. Simultaneously, ground reaction forces (GRFs) were recorded at 1200 Hz through the treadmill’s embedded force plates. Each runner then ran 10 km on a paved trail at their self-selected pace. Immediately following the run, reflective markers were reattached, guided by markings placed before the run, and a 30-second post-run trial of the video and GRF data were recorded. Video data were analyzed using Kinovea software to measure the kinematic variables of interest. Paired t-tests with Bonferroni corrections were used to find if significant differences existed between pre- and post-run data for all kinematic and kinetic variables.ResultsNo significant or clinically relevant differences existed between the pre- and post-run measurements for the kinematic or kinetic variables. The only significant difference noted between the ultra-runners and recreational runners was that the ultra-runners had significantly higher cadence (p=0.045).ConclusionsA 10 km run at a self-selected pace did not result in change in the mean kinematic or kinetic variables in this group of experienced runners. Ultra-runners employ higher cadence than recreational runners, but their kinematics and kinetics are similar.Level of EvidenceLevel 3