Influence of Fatigue on Vertical Leg Stiffness and Stiffness Recruitment Strategies in Males and Females

Padua, Darin A.; Carcia, Christopher R.; Gansneder, Bruce M.; Perrin, David H.; Arnold, Brent L.; Granata, Kevin P.

doi:10.1097/00005768-200205001-00563

Cited by 70 publications

(138 citation statements)

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“…This may explain the decrease of muscle activity of both calf and quadriceps muscles with knee muscle fatigue. The decrease in the biceps femoris and tibialis activity with knee muscle fatigue might indicate a compensatory strategy [20] to improve knee and ankle mechanical efficiency [21,22].…”

Section: Discussionmentioning

confidence: 99%

The effect of muscle fatigue on the last stride before stepping down a curb

et al. 2013

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Section: Discussionmentioning

confidence: 99%

The effect of muscle fatigue on the last stride before stepping down a curb

et al. 2013

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“…We used this specific coactivation index to compare our results with recent findings on fatigue effects on movement biomechanics. 27,32 Agonist:antagonist EMG ratios of 1.0 indicate equal activation of the 2 antagonistic muscles, whereas coactivation ratios greater than 1.0 indicate increased agonist (VM or GAS) activation compared with the antagonist (BF or TA) muscles and vice versa. 27 Ratios less than 1 indicate high activity of the antagonist relative to the agonist muscles.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the absence of change in the coactivation ratio, the higher activation of both agonist and antagonist knee muscles postfatigue would indicate a stiffer joint before impact, which may increase joint stability. 20,27 Contact and Initial Response During foot contact, the quadriceps muscle group acts eccentrically to maintain hip and knee movement while the hamstrings coactivate concentrically. 24,36 In this phase, both muscles display high activation levels and, therefore, both contribute to joint stability by cocontracting.…”

Section: Preactivationmentioning

confidence: 99%

“…The increase in quadriceps activation after fatigue has often been called a quadriceps-dominant strategy, 27,32,37 and it might indicate that either that participants placed greater reliance on the quadriceps muscles postfatigue or that fatigue resulted in increased VM motor-unit recruitment to produce the same amount of force. Greater quadriceps muscle activation with lengthening 24,38 may be required to prevent the knee from collapsing into flexion.…”

Section: Preactivationmentioning

confidence: 99%

“…27 To our knowledge, muscle-coactivation strategies in more than 1 joint during running under fatigue conditions have not been investigated.…”

mentioning

confidence: 99%

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Muscle Coactivation Before and After the Impact Phase of Running Following Isokinetic Fatigue

Kellis

Zafeiridis

Amiridis

2011

Journal of Athletic Training

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Context: The effects of fatigue on impact loading during running are unclear, with some authors reporting increased impact forces and others reporting decreased forces.Objective: To examine the effects of isokinetic fatigue on muscle cocontraction ratios about the knee and ankle during running.Design: Cross-sectional study. Setting: Neuromechanics laboratory.Patients or Other Participants: Female middle-distance runners (age 5 21.3 6 1.93 years) with at least 5 years of training experience.Intervention(s): Participants ran on the treadmill at 3.61 m/s before and immediately after the fatigue protocol, which consisted of consecutive, concentric knee extension-flexion at 1206/s until they could no longer produce 30% of the maximum knee-extension moment achieved in the familiarization session for 3 consecutive repetitions.Main Outcome Measure(s): Electromyographic (EMG) amplitude of the vastus medialis (VM), biceps femoris (BF), gastrocnemius (GAS), and tibialis anterior (TA) was recorded using surface electrodes. Agonist:antagonist EMG ratios for the knee (VM:BF) and ankle (GAS:TA) were calculated for the preactivation (PR), initial loading response (LR 1 ), and late loading response (LR 2 ) phases of running. Hip-, knee-, and ankle-joint angular displacements at initial foot contact were obtained from 3-dimensional kinematic tracings.Results: Fatigue did not alter the VM:BF EMG ratio during the PR phase (P . .05), but it increased the ratio during the LR 1 phase (P , .05). The GAS:TA EMG ratio increased during the LR 1 phase after fatigue (P , .05) but remained unchanged during the PR and LR 2 phrases (P . .05).Conclusions: The increased agonist EMG activation, coupled with reduced antagonist EMG activation after impact, indicates that the acute decrease in muscle strength capacity of the knee extensors and flexors results in altered muscleactivation patterns about the knee and ankle before and after foot impact.Key Words: biomechanics, muscle fatigue, joint stability Key PointsN After an isokinetic fatigue protocol for the knee-extensor and knee-flexor muscles, participants contacted the ground with a greater knee-flexion angle.N An antagonist inhibition strategy about the knee and ankle was noted, as was a quadriceps-dominant strategy during the preactivation and initial contact phases of running.

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