Introduction: Arthrogenic muscle inhibition is the onset of muscle weakness due to impaired voluntary muscle activation that usually onsets after knee impairments, even though there is no injury on muscle or nerve. Arthrogenic muscle inhibition is a defensive mechanism which prevents potentially dangerous loads of the joint immediately after injury. Later in rehabilitation it slows down normal regeneration because it prevents strenghtening of the muscle and eventually leads to long-lasting atrophy and weakness. Ischemic exercise with low loads is becoming an alternative to standard exercise protocols with high loads for improvement of muscle strength and hipertrophy, especially when high loading of the joint is contraindicated. Purpose: The purpose of this double case report was to compare the effects of ischemic exercise with low loads and exercise with low loads on maximal voluntary isometric contraction, isometric endurance and function of the knee joint. Methods: A four week intervention with ischemic and standard low load exercise took place in two subjects with knee joint injury. The protocol lasted four weeks with three training units per week. During every training unit we asked the subject about their perception of effort, muscle pain and knee pain on 10 point Borg scale. We measured maximal voluntary isometric contraction and isometric endurance with isometric dinamometer pre- and post-intervention, subjects also took subjective Lysholm test pre- and post-intervention. Results: Ischemic exercise was more effective in subjective functional progress. Low load exercise was more effective in maximal voluntary isometric contraction and isometric endurance. Discussion and conclusion: Blood flow restricted exercise was more effective in improving subjective function, low load exercise was more effective in improving strength and endurance. Due to different begining levels of arthrogenic muscular inhibition of the subjects, we cannot generalize these results.
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