Effects of task and hip-abductor fatigue on lower limb alignment and muscle activation

The Effect of Fatigue on Trunk and Pelvic Jump-Landing Biomechanics in View of Lower Extremity Loading: A Systematic Review

Fatigue has often been considered a risk factor for developing sports injuries, modulating lower extremity jump-landing biomechanics. The impact of fatigue on proximal trunk and pelvic biomechanics has been suggested to play an important role in lower extremity loading and injury risk, yet the available evidence remains ambiguous as the trunk and pelvis were often not the primary focus of research. Therefore, the purpose of this systematic review was to determine how fatigue affects trunk and pelvic three-dimensional jump-landing biomechanics. PubMed (MEDLINE), Web of Science, Embase, CINAHL and SPORTDiscus were consulted up to and including April 2022 for potential studies investigating the effect of fatigue on trunk and pelvic kinematics, kinetics and/or muscular activity during jump-landing tasks in healthy, physically active populations. Methodological quality of the studies was assessed by the modified Downs and Black checklist. Twenty-one studies were included and methodological quality was moderate to high among these studies. The results indicate prevailing evidence for more trunk flexion during standardized jump-landing tasks after lower extremity muscle fatigue. Otherwise, lumbo-pelvic-hip muscle fatigue does not seem to elicit major detrimental changes to these jump-landing biomechanics. Although a wide variability of trunk and pelvic jump-landing strategies was observed, the results provide evidence for increased trunk flexion after lower extremity muscle fatigue. This proximal strategy is suggested to help unload fatigued lower extremity structures and lack of this compensation might increase knee injury risk.

Are proximal and distal neuromuscular parameters able to predict hip and knee frontal plane kinematics during single-leg landing?

OBJECTIVE

To determine if proximal and distal neuromuscular parameters (EMG amplitude and median frequency - MDF) can predict frontal plane kinematics during single-leg landing.

STUDY DESIGN

Cross sectional study.

SETTING

Laboratory.

PARTICIPANTS

Fifteen participants (7 female) performed six single-leg landings with measures of frontal plane kinematics and EMG obtained 230 ms after first foot contact, totalizing 90 landings.

MAIN OUTCOME MEASURES

(i) 2D hip adduction [hip ADD] and knee frontal plane projection angle [knee FPPA]; (ii) EMG amplitude and MDF of gluteus medius [GMed], tensor fascia latae [TFL], peroneus longus [PL] and tibialis anterior [TA].

RESULTS

We observed that MDF of TA was a significant predictor of hip ADD (p = 0.037; β = -0.049 Hz; R²c = 0.30). Also, MDF of PL was significant predictor of knee FPPA (p = 0.043; β = 0.042 Hz; R²c = 0.37). Hip muscles and EMG amplitude parameters were not considered predictors of frontal plane kinematics.

CONCLUSION

The firing frequency of ankle muscles predicted the variance of hip and knee frontal plane kinematics during single-leg landing.

The influence of task type and movement speed on lower limb kinematics during single-leg tasks

BACKGROUND

Single-leg squats and step-downs are commonly used to assess kinematic variables that may be linked to injuries. Task type and movement speed may influence the outcomes of interest because of different balance requirements.

RESEARCH QUESTION

What is the influence of task type and movement speed on lower limb kinematics?

METHODS

This is a cross-sectional within-subjects study where 22 physically active females performed three single-leg functional tasks (Squat, Anterior step-down, and Lateral step-down) at three movement speeds (slow [5 s], fast [2 s], and self-selected), while three-dimensional kinematic variables were recorded. Displacement values from the initial position in single-leg support until 60° or peak knee flexion were calculated. Two-way repeated measures ANOVA was used to compare tasks and speeds, and Cohen's d effect size (ES) was calculated for significant pairwise comparisons.

RESULTS

At 60°, lateral step-down presented the greatest hip adduction (large ES) and internal rotation (small ES). The anterior step-down had the lowest knee abduction displacement while the squat had the greatest (small to medium ES). At peak knee flexion, values increased but differences between tasks followed a similar pattern. Slow speed induced smaller displacement angles at the knee and hip (trivial to small ES).

SIGNIFICANCE

When knee abduction is the variable of interest, the SLS may be the best test since it elicits the greatest displacement, but when evaluating hip motion, SD_LAT might be best. Knee abduction and internal rotation were lowest in the slow condition, suggesting that faster speed may be more appropriate to detect abnormal movement patterns. However, the small difference in absolute values (i.e., degrees of movement) may indicate that the differences are not clinically significant, particularly for speed comparisons. Researchers and clinicians should take this into consideration when choosing the most appropriate task and the instruction to give during its execution.