Trunk extensor fatigue influences trunk muscle activities during walking gait

Area of Science:

• Biomechanics
• Neuromuscular Physiology
• Sports Medicine

Background:

• Prolonged physical activity can lead to neuromuscular fatigue.
• Neuromuscular fatigue alters muscle responses and may increase injury risk, particularly for the low back.
• Understanding these adaptations is crucial for preventing activity-related injuries.

Purpose of the Study:

• To investigate myoelectric changes in trunk musculature during walking after inducing neuromuscular fatigue in trunk extensors.
• To observe how fatigue affects the activation patterns and amplitudes of key trunk muscles.
• To assess the potential link between fatigue-induced muscle changes and spinal stability.

Main Methods:

• Fourteen healthy women underwent fatiguing exercises targeting trunk extensors.
• Surface electromyography (EMG) recorded activity of lumbar paraspinal (LP), rectus abdominis (RA), and external oblique (EO) muscles.
• Walking trials were conducted before and after fatigue, with synchronized EMG and kinematic data.

Main Results:

• Significant temporal shifts in LP and RA activity occurred at contralateral heel contacts during 70% maximal effort.
• Increased RA amplitude and temporal shifts in EO activity were observed at 50% maximal effort.
• Fatigue altered muscle activation timing and intensity during walking.

Conclusions:

• Neuromuscular fatigue impacts trunk muscle coordination and activation patterns during locomotion.
• Altered paraspinal muscle function post-fatigue may reduce trunk support and spinal stiffness.
• These findings highlight a potential mechanism for increased low back injury risk following prolonged physical activity.