Between-limb differences in running technique induces asymmetric negative joint work during running

Inter-limb difference of mechanical work in limb length discrepancy

BACKGROUND

Limb length discrepancy (LLD) is common and is associated with musculoskeletal disorders. Selection of adaptation strategies, the side more susceptible to complications, and the relationships between LLD magnitude and musculoskeletal complications are unclear. To elucidate these ambiguities, studies on gait parameters in LLD have been conducted. However, studies on inter-limb difference of mechanical work in LLD are rare.

RESEARCH QUESTION

To investigate whether inter-limb differences in mechanical work in LLD and the relationship between LLD magnitude and mechanical work performed by each lower limb are significant.

METHODS

Thirty-seven participants with LLD and without neuromuscular disorders disturbing normal gait were included. Three-dimensional motion analysis was conducted to obtain data on mechanical work, including joint work and the individual limb method (ILM) work. Mechanical work performed by the longer and shorter limbs was compared using paired t-test. Relationships between LLD and mechanical work were investigated using correlation and multiple regression analyses in both limbs. Eighteen participants had LLD > 20 mm, large group (LG), and 19 had LLD < 20 mm, small group (SG). Data exploration was conducted for the effect of LLD severity (LG vs. SG) on mechanical work.

RESULTS

LLD showed significant inter-limb difference of mechanical work and negative correlations with positive and negative ILM work performed by the shorter limb. The shorter limb in SG performed significantly larger positive ILM work than the longer limb, whereas the longer limb in LG performed significantly larger negative ILM work than the shorter limb.

SIGNIFICANCE

LLD showed inter-limb difference of ILM work and different adaptation strategies between LG and SG. These differences attribute to the decrease in ILM work performed by the shorter limb with the increase in LLD. Mechanical work including ILM work should be included in future studies to prevent complications and development of treatment methods for LLD.

Effects of Foot Strike Techniques on Running Biomechanics: A Systematic Review and Meta-analysis

CONTENT

Distance running is one of the most popular physical activities, and running-related injuries (RRIs) are also common. Foot strike patterns have been suggested to affect biomechanical variables related to RRI risks.

OBJECTIVE

To determine the effects of foot strike techniques on running biomechanics.

DATA SOURCES

The databases of Web of Science, PubMed, EMBASE, and EBSCO were searched from database inception through November 2018.

STUDY SELECTION

The initial electronic search found 723 studies. Of these, 26 studies with a total of 472 participants were eligible for inclusion in this meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Means, standard deviations, and sample sizes were extracted from the eligible studies, and the standard mean differences (SMDs) were obtained for biomechanical variables between forefoot strike (FFS) and rearfoot strike (RFS) groups using a random-effects model.

RESULTS

FFS showed significantly smaller magnitude (SMD, -1.84; 95% CI, -2.29 to -1.38; P < 0.001) and loading rate (mean: SMD, -2.1; 95% CI, -3.18 to -1.01; P < 0.001; peak: SMD, -1.77; 95% CI, -2.21 to -1.33; P < 0.001) of impact force, ankle stiffness (SMD, -1.69; 95% CI, -2.46 to -0.92; P < 0.001), knee extension moment (SMD, -0.64; 95% CI, -0.98 to -0.3; P < 0.001), knee eccentric power (SMD, -2.03; 95% CI, -2.51 to -1.54; P < 0.001), knee negative work (SMD, -1.56; 95% CI, -2.11 to -1.00; P < 0.001), and patellofemoral joint stress (peak: SMD, -0.71; 95% CI, -1.28 to -0.14; P = 0.01; integral: SMD, -0.63; 95% CI, -1.11 to -0.15; P = 0.01) compared with RFS. However, FFS significantly increased ankle plantarflexion moment (SMD, 1.31; 95% CI, 0.66 to 1.96; P < 0.001), eccentric power (SMD, 1.63; 95% CI, 1.18 to 2.08;P < 0.001), negative work (SMD, 2.60; 95% CI, 1.02 to 4.18; P = 0.001), and axial contact force (SMD, 1.26; 95% CI, 0.93 to 1.6; P < 0.001) compared with RFS.

CONCLUSION

Running with RFS imposed higher biomechanical loads on overall ground impact and knee and patellofemoral joints, whereas FFS imposed higher biomechanical loads on the ankle joint and Achilles tendon. The modification of strike techniques may affect the specific biomechanical loads experienced on relevant structures or tissues during running.