Exercise Intermittent Isometric Handgrip and Blood Flow Restriction
Condition: Sarcopenia
MeSH terms: Sarcopenia
Study type: Interventional

Summary: 
      Isometric handgrip exercises are used to explain the effects of fatigue on the strength and
      activation of the muscles involved. Blood flow available at the time of exercise can
      influence this fatigue process, as some studies demonstrate changes in the pattern of muscle
      recruitment and strength recovery when the exercise is performed in combination with an
      external total obstruction (through a pressure cuff or tourniquet ) blood flow. Low intensity
      exercises associated with external partial obstruction of blood flow has been widely used and
      studied, mainly due to its effect on increasing strength and muscle hypertrophy, often
      comparable to those observed in conventional exercises (ie, without external obstruction of
      blood flow) High intensity. Despite the vast literature on this method, some topics need to
      be better informed about the underlying neuromuscular physiology to such effects (strength
      and hypertrophy) and the process of fatigue during isometric exercises associated with
      partial obstruction of blood flow. The aim of this study is to evaluate the acute effects on
      neuromuscular response in healthy adults undergoing an intermittent isometric exercise
      protocol with different levels of external compression. In a study of the "crossover" male
      volunteers will be submitted to three intermittent isometric exercise protocols (with a load
      of 45% of maximum voluntary isometric strength) associated with three different levels of
      obstruction (held by a pressure cuff) blood flow (total obstruction, partial obstruction and
      free blood flow). The protocols will be performed on three different days (with a minimum of
      48 hours between them). Will be considered as acute neuromuscular responses spending time to
      failure in the task, the electromyographic activity of the flexor muscles of the wrist and
      fingers, and the recovery curve of maximum voluntary isometric strength after exercise. The
      main hypothesis of this study is that exercise is performed when associated with partial
      obstruction of blood flow, the time spent until the failed job is similar to that seen when
      exercise is performed with free blood flow, and the recovery of strength and
      electromyographic activity will be similar to that observed in the exercise associated with
      total obstruction of blood flow.
    

Detailed description: 
      Muscle fatigue is a process widely disbelieved and studied in the literature. Isometric
      handgrip exercises have been widely utilized to explain the effects of fatigue on the
      strength and activation of the muscles involved in certain exercises. Among the many factors
      that can influence the process of muscular fatigue, blood flow available at the time of
      exercise is an aspect of fundamental importance, as some studies demonstrate changes in the
      pattern of muscle recruitment and strength recovery when the exercise is performed associated
      with an external obstruction of blood flow.

      Resistance exercise associated with partial obstruction of blood flow (ischemic exercise) is
      gaining notoriety in the scientific environment, mainly due to strong evidence indicating
      that such activity can increase strength and muscle hypertrophy, even when performed with low
      intensity loads. The underlying neuromuscular mechanisms such effects are still partially
      unknown, and some studies have shown differences in the recruitment of motor units during its
      execution, and the relationship fatigue-strength after ischemic resistance exercise.
      Nevertheless, there are still some gaps in the literature regarding the neuromuscular
      responses during and after unilateral intermittent isometric handgrip protocols to failure in
      the associated task to partial obstruction of blood flow.

      Evidence suggests that the total obstruction of blood flow decreases performance and
      accelerates the recovery of the isometric strength after fatigue protocols, but the effects
      of partial obstruction on these variables remain unknown. In the above so far, it seems that
      isometric fatigue protocols associated with remote obstruction (away from the venue of the
      exercise) blood flow can influence acutely in strength members at a distance, but it is not
      known as a protocol unilateral isometric fatigue associated with partial and complete
      obstruction of blood flow can influence acutely the strength of the contralateral limb (ie,
      not subject to any type of exercise). Thus, the realization of this study is justified by the
      possibility of answering these questions still little studied, with regard to neuromuscular
      factors of ischemic resistance training.
    

Intervention name(s): Isometric exercise Intermittent
Intervention type(s): Other
Intervention description(s): Intermittent isometric exercise is characterized by an interval muscle contraction (one period and another relaxed contracted period) in which there is no generation of voltage change in the length of the muscle fiber.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science