Sex differences in gluteal muscle forces during running

The relationship between hamstring strength tests and sprint performance in female Gaelic footballers: A correlation and linear regression analysis

OBJECTIVES

To investigate the relationships between handheld dynamometer (HHD), isokinetic and Nordic hamstrings exercise (NHE) measurements of knee flexor strength and their association with sprinting performance.

DESIGN

Cross-sectional.

METHODS

The relationships between HHD (prone isometric, prone break and supine break knee flexor strength tests), isokinetic and NHE peak knee flexor strength measures were examined using Pearson product correlations on 38 female footballers. A linear regression analysis was also performed for each pair of dependent variables (10 and 30 metre sprint times) and independent predictor variables (average relative peak torque for HHD, isokinetic and NHE testing).

RESULTS

There were good correlations between HHD tests (r = 0.81-0.90, p < 0.001, R2 = 0.65-0.82), moderate correlations between HHD and isokinetic peak torque, (r = 0.61-0.67, p < 0.001, R2 = 0.37-0.44) and poor association between the HHD peak torques and isokinetic work (r = 0.44-0.46, p = 0.005-0.007, R2 = 0.20-0.21) and average power (r = 0.39-0.45, n = 36, p = 0.006-0.019, R2 = 0.15-0.22). There was a poor association between NHE peak torque and isokinetic total work (r = 0.34, p = 0.04, R2 = 0.12). No associations between knee flexor strength and sprint times were observed (p = 0.12-0.79, r2 = 0.002-0.086).

CONCLUSIONS

Moderate to good correlations within HHD testing and poor to moderate correlations between HHD and isokinetic testing were observed. HHD knee flexor torque assessment may be useful to regularly chart the progress of hamstring rehabilitation for female footballers. Knee flexor strength assessments were not associated with sprint times in female footballers. Other aspects of knee flexor strength and sprint performance should be investigated to assist clinicians in making return to running and sprinting decisions in this population.

A comparison of five methods to normalize joint moments during running

BACKGROUND

Net joint moments (NJM) are typically normalized for a (combination of) physical body characteristics such as mass, height, and limb length using ratio scaling to account for differences in body characteristics between individuals. Four assumptions must be met when normalizing NJM data this way to ensure valid conclusions. First, the relationship between the non-normalized NJM and participant characteristic should be linear. Second, the regression line between NJM and the characteristic(s) used should pass through the origin. Third, scaling should not significantly perturb the statistical distribution of the data. Fourth, normalizing a NJM should eliminate its correlation with the characteristic(s) normalized for.

RESEARCH QUESTION

This study assessed these assumptions using data collected among 59 individuals running at 10 km h-1.

METHODS

Standard inverse dynamics analyses were conducted, and ratios were computed between the sagittal-plane hip, knee and ankle NJM's and the participant's mass, height, leg length, mass × height, and mass × leg length.

RESULTS

The most important finding of this study was that none of the scaling variables fulfilled all assumptions across all joints. However, scaling by mass, mass*height and mass*leg length satisfied the assumptions for the knee joint moment and log-transformed hip joint moment, suggesting these methods generally performed best.

SIGNIFICANCE

Our findings suggests that scaling by mass, mass*height and mass*leg length may be considered to normalize joint moments during running. Nevertheless, we urge researchers to check the statistical assumptions to ensure valid conclusions. We provide supplementary code to check the statistical assumptions, and discuss consequences of inappropriate scaling.

Sex-specific differences in biomechanics among runners: A systematic review with meta-analysis

Patellofemoral disorders are more common in female runners compared to their male counterparts. Differences in biomechanical characteristics between groups of runners could provide insight into the causes of higher rates of injury in female versus male runners, which would be useful to physical therapists and athletic trainers in development of individualized injury prevention programs. This review compares the differences in biomechanical characteristics between female and male runners. Electronic databases, including PubMed, Scopus, Web of Science, and Embase were searched in December 2021 for studies evaluating sex-specific differences in lower limb mechanics of healthy participants during running. Two independent reviewers determined the inclusion and quality of each research paper. Meta-analyses were used where possible. A total of 13 studies were selected. Means and standard deviations of reported data were retrieved from each selected paper for comparison of results. Three biomechanical variables, including dynamics, muscle activation, and kinematics, were compared between female and male runners. However, no differences were found in kinetic variables or muscle activation between groups due to insufficient data available from the selected studies. Meta-analyses of kinematic variables revealed that female runners exhibited significantly greater hip flexion angle, hip adduction angle, and hip internal rotation angle, but smaller knee flexion angle compared to male runners during running. We found significant differences in kinematic variables between female and male runners, which could influence the training advice of physical therapists and athletic trainers who work with runners, and inform the development of injury prevention programs.

Relationship among maximum hip isometric strength, hip kinematics, and peak gluteal muscle force during running

OBJECTIVE

To determine if there is a relationship among isometric hip strength, hip kinematics, and peak gluteal muscle forces in cross-country runners during running.

DESIGN

Cross Sectional.

SETTING

University Biomechanics Laboratory.

PARTICIPANTS

Forty-six NCAA Division III collegiate cross-country runners (18 males, 28 females).

MAIN OUTCOME MEASURES

Pearson correlation coefficients were used to describe relationships among isometric hip strength, hip kinematics, and peak gluteal muscle forces during the stance phase of running. Strength of correlations were interpreted as little to no relationship (r < 0.25), fair relationship (0.25 ≤ r < 0.5), moderate relationship (0.5 ≤ r < 0.75), and strong relationship (r ≥ 0.75). Correlations were considered significant if p < 0.05.

RESULTS

Little to no relationships were found among isometric hip strength and gluteal muscle forces during running (r < 0.25). A fair relationship was present between prone external rotation isometric hip strength and peak hip adduction (0.25 <r < 0.5). Little to no relationship was shown between gluteus medius force and hip internal rotation. Moderate relationships were present among peak gluteus medius and minimus muscle forces and peak hip adduction (0.5 <r < 0.75).

CONCLUSION

Isometric hip strength does not appear to be related to gluteal muscle forces and hip kinematics during the stance phase of running while gluteal muscle force was moderately related to hip adduction. Factors other than strength may be related to muscle force production and hip kinematics during running.

Biomechanical risk factors for running-related injury differ by sample population: A systematic review and meta-analysis

BACKGROUND

The role of biomechanical variables of running gait in the development of running related injury has not been clearly elucidated. Several systematic reviews have examined running biomechanics and its association with particular running related injuries. However, due to retrospective designs, inferences into the cause of these injuries are limited. Although prospective studies have been completed, no quantitative analysis pooling these results has been completed.

METHODS

A systematic review of MEDLINE, CINAHL, and PubMed was completed. Articles included used prospective study designs, human subjects currently completing a regular running program, and a minimum 12-week follow-up period. Excluded articles had no biomechanical data reported, participants who were beginning runners or military recruits, or had an intervention provided.

FINDINGS

Thirteen studies met these criteria. Pooled analyses were completed if two or more studies were available with samples that investigated the same sex and competition level. A qualitative synthesis was completed when pooled analysis was not possible. Five unique running samples were identified and allowed for pooled analyses of variables in mixed-sex collegiate runners and female recreational runners. Moderate evidence exists for increased hip adduction and reduced peak rearfoot eversion as risk factors for running related injury in female recreational runners. Variables differed in other samples of runners.

INTERPRETATION

A runner's sex and competition level may affect the relationship between biomechanical factors and the development of running related injury. Hip adduction and rearfoot eversion may be important factors related to running related injury in female recreational runners. Further investigation of biomechanical factors in running injury is warranted.

Muscle force characteristics of male and female collegiate cross-country runners during overground running

Males and females demonstrate unique running mechanics that may contribute to sex-related differences in common running related injuries. Understanding differences in muscle forces during running may inform intervention approaches, such as gait retraining addressing muscle force distribution. The purpose of this study was to compare muscle force characteristics and inter-trial variability between males and females during running. Twenty female and 14 male collegiate cross-country runners were examined. Three-dimensional kinetic and kinematic data were collected during overground running and used to estimate muscle forces via musculoskeletal modelling. Principle components analysis was used to capture the primary sources of variance from the muscle force waveforms. The magnitude of the forces for the hamstrings, gastrocnemius, and soleus muscles were higher across the majority of stance in male runners regardless of footstrike pattern. Males also demonstrated greater inter-trial variability in the timing of the peak gluteus maximus force and the magnitude of local peaks in the gastrocnemius force waveform. Male and female collegiate cross-country runners appear to employ unique lower extremity muscle force characteristics during overground running.