The effects of eccentric exercise-induced fatigue on position sense during goal-directed movement

Abstract

We investigated the impairment of position sense associated with muscle fatigue. In Exp. 1, participants performed learned eccentric extension (22 °/s) movements of the elbow as the arm was pulled through the horizontal plane without vision of the arm. They opened their closed right hand when they judged it to be passing through a target. Dynamic position sense was assessed via accuracy of limb position to the target at time of hand opening. Eccentric movements were performed against a flexion load (10% of flexion MVC). We investigated performance under conditions with and without biceps vibration, as well as before and after eccentric exercise. In Exp. 2, a motor was used to extend the participant's limb passively. We compared conditions with and without vibration of the lengthening but passive biceps, before and after exercise. In Exp. 1, vibration of the active biceps resulted in participants opening their hand earlier ( [95% CI] -5.52° [-7.40, -3.63]) compared to without vibration. Exercise reduced flexion MVCs by ~44%, and participants undershot the target more (-5.51° [-9.31, -1.70]) in the post-exercise block during control trials. Exercise did not influence the persistence of the vibratory illusion. In Exp. 2, vibration resulted in greater undershooting (-2.99° [-3.99, -1.98]) compared to without vibration, before and after exercise. Although exercise reduced MVCs by ~50%, the passive task showed no effects of exercise. We suggest that the CNS continues to rely on muscle spindles for limb position sense, even when they reside in a muscle exposed to fatiguing eccentric contractions.

Prioritized adjustments in posture stabilization and adaptive reaching during neuromuscular fatigue of lower-limb muscles

“…Exercise-induced neuromuscular fatigue (NMF) is characterized by a temporary reduction in the ability of a muscle to produce force and/or power, (1)(2)(3). This phenomenon affects various dimensions of human motor function, including the planning of motor activities (4-7), coordination (8)(9)(10)(11), balance (12), sensorimotor integration (13,14), limb proprioception (15,16) and muscle activation patterns (17). Furthermore, NMF adversely affects gait characteristics (18)(19)(20)(21) and posture stabilization (22)(23)(24).…”

Kinematics but not kinetics alterations to single-leg drop jump movements following a subject-tailored fatiguing protocol suggest an increased risk of ACL injury

“…The state of fatigue often results in performance degradation, observed during the execution of several motor tasks including balance ( 4 ), walking ( 5 – 8 ), reaching movements ( 9 ), dynamic loading during running ( 10 , 11 ), and shock absorption during landing ( 12 , 13 ). Furthermore, recent results suggests that neuromuscular fatigue also affects basic mechanisms of human motor control, causing transient alterations to movement planning ( 14 ), sensorimotor integration ( 15 , 16 ), joint position sense ( 17 ) and postural control ( 18 – 20 ). Whether these alterations in force generation and control mechanisms lead to inappropriate motor commands ( 21 ) that increase the risk of musculoskeletal injury is still unclear.…”

Mountain Hiking: Prolonged Eccentric Muscle Contraction during Simulated Downhill Walking Perturbs Sensorimotor Control Loops Needed for Safe Dynamic Foot–Ground Interactions

“…Furthermore, the activation of rapid reflex loops triggered by proprioceptive signals can be observed in balance tasks on unstable surfaces [ 7 , 22 , 23 ]. While the effects of fatiguing eccentric exercise on changes in proprioception and joint position sense are well-studied [ 24 , 25 ], research on non-fatiguing protocols is lacking. Prolonged eccentric muscle activity, as experienced during downhill walking, might interfere with these proprioceptive mechanisms and, therefore, contribute to heightened fall risk in descents [ 2 , 17 , 26 ].…”