Comparison of Muscle Activity in Exercise Bike and Elliptical Trainer in Individuals With Spinal Cord Injury
Condition: Spinal Cord Injury
MeSH terms: Spinal Cord Injuries; Wounds and Injuries
Study type: Observational

Summary: 
      Spinal cord injury is caused by any harmful process in the spinal cord, impairing its
      function, generating loss of muscle strength, impairing orthostatism and walking. In
      rehabilitation, some strategies are used to activate the muscles involved in the gait of
      these individuals, including the ergometric bicycle and the elliptical. Understanding the
      pattern of muscle activation generated by these methods is important to answer questions
      arising from clinical practice. Thus, we seek to verify the pattern of muscle activation of
      the vastus laterals, vastus medialis, gluteus medius, tibialis previous, rectus abdominis and
      paravertebral muscles during exercises with ellipticals and ergometric bicycle with and
      without electromyography biofeedback in individuals with spinal cord injury. Cross-sectional
      study of the type crossover. Individuals will sign the Informed Consent Form (FICF) and
      answer the identification form. They will be evaluated for functionality using the Functional
      Independence Measure (FIM), injury classification by the American Spinal Injury Association
      (ASIA) and muscle tone by the modified Ashworth scale. Later, they will be randomized to
      define the order of the devices in which they will be evaluated. Muscle activity will be
      verified with electromyography of the paravertebral, abdominal, vastus laterals, vastus
      medialis, gluteus medius and tibialis anterior unilateral muscles on the right side of
      individuals, comparing muscle activation during exercise cycling, elliptical and adding
      biofeedback in both modalities. The wash-out interval between each evaluation will be 7 days.
      We hypothesize that the elliptical with biofeedback will cause greater activation of the
      assessed muscles.
    

Detailed description: 
      Spinal cord injury is caused by any mechanism of injury that attacks and impairs the
      integrity of the spinal cord, preventing it from performing its functions.

      It is estimated that the incidence of spinal cord trauma in Brazil is greater than 10,000 new
      cases per year, 80% being men and 60% aged between 10 and 30 years, with trauma being the
      predominant cause.

      Initial trauma causes injuries by mechanical force, which can cause damage by compression,
      laceration or section. Any damage to this structure triggers an inflammatory response with
      edema and, consequently, ischemia, gradually aggravating the injury process, compromising
      neuronal homeostasis.

      The ASIA scale is globally standardized to assess the type of injury. With this scale it is
      possible to assess the sensory levels preserved through the corresponding dermatomes at each
      level, testing the superficial and deep sensitivity below the level of the lesion. Motor
      level is assessed by myotomes, grading the strength of each muscle corresponding to spinal
      levels.

      Neurological disorders resulting from spinal cord injury compromise motor, sensory and
      autonomic functions, resulting in total or partial loss of voluntary muscle activity,
      sensitivity, functioning of the urinary, intestinal, respiratory, circulatory and
      reproductive systems. At the corresponding level, epicritic sensitivity is preserved as it
      courses in the ipsilateral posterior funiculus. There will also be loss of painful and
      thermal sensations due to disruption of the nerve fibers that cross the white commissure.

      Muscle weakness is the most limiting impairment caused by neurological damage. There is a
      limitation of activity and several restrictions, which influence the quality of life. The
      deficit in muscle strength leads to limitations in performing a series of functional
      activities. The strength of major muscles or muscle groups contributes to functional
      capacity. Functional independence is positively associated with the peak torque performed by
      the muscles used to perform a given task.

      Physiotherapy has an essential role in the acute and chronic care of these patients, acting
      as a guide, promoting a greater level of independence, and should aim at preventing
      deformities, modulating muscle tone, enhancing respiratory muscle function, using various
      techniques such as transfer training, postural changes, wheelchair handling, balance
      training, orthostatism and, within the patient's functional potential, restoration of gait
      and lower limb function, benefiting the performance of activities of daily living, and
      quality of life.

      In spinal cord injury, the deficit of muscle activation compromises many functional actions
      such as the development of gait, but there are encouraging results with physical therapy
      techniques that are effective in improving the prognosis of locomotor movement.

      Therefore, a set of factors influence gait, which results from an interaction and
      organization of the neural and mechanical systems, in addition to musculoskeletal dynamics,
      modulation of the upper nervous system and the afferent pathway, which is also controlled by
      the Central Pattern Generator through a programming based on a predetermined spinal circuit,
      capable of producing a rhythm associated with gait.

      The Central Pattern Generator is a network of neurons that can produce a variety of movement
      activity, responsible for automating gait, which depends on feedback from proprioceptors and
      higher nerve interactions. This generator is responsible for rhythmic motor patterns,
      generated by inhibitory and excitatory processes of the lower limbs during movements. There
      is an excitatory and inhibitory relay between agonist and antagonist muscles alternating
      between limbs.

      In these patients, this neuronal domain is compromised, making it difficult to modulate
      muscle activation. However, recent studies have suggested the existence of effective
      responses in locomotor training with partial body weight support, leading to an improvement
      in locomotor patterns.

      Locomotor training with partial weight bearing for neurological patients has been studied and
      considered an important therapeutic mechanism in order to reduce the effects caused by
      changes in spinal cord injury, being able to fully explore the activation of the patient's
      potential inducing neural plasticity, providing motor related relearning to the specific
      task.

      Locomotor exercises are based on standardized neural activity. Process by which the central
      nervous system develops its structure and function in human growth. Continuous repetition of
      movement can help create this neural pattern in the brain and spinal cord.

      There are some devices used in the physiotherapy routine that work rhythmically, for
      locomotor training and activation of several muscles recruited in the performance of these
      motor tasks, including the elliptical and the bicycle.

      The elliptical is a walking simulator and can also be used for this purpose, which is
      advantageous in this modality as it reduces the impact on joints, benefiting individuals with
      impaired balance, as the feet remain in continuous contact with the support surface.

      The elliptical provides training with cyclic movement, alternating the lower limbs through a
      system of levers and sliding axles. When compared to walking on a treadmill, studies suggest
      that the elliptical reduces plantar pressure in the contact phase of the heel, in addition to
      reducing the impact of the foot with the contact surface, increasing muscle involvement and
      increasing the contact phase. individuals with balance deficits.

      During the use of the elliptical, the trunk, hip and knee maintain a greater degree of
      flexion, indicating greater muscle activation of the glutes and vastus lateralis, compared to
      walking on the ground.

      In addition to the elliptical, the static bicycle, used in routine motor rehabilitation, can
      also be a means of training and muscle recruitment. There is movement of the knees during
      pedaling, the extension being the most impactful, since knee flexion is passive, as there is
      no greater activation of the flexors.

      The pedaling variation is composed of two phases, the ascending, when the pedals move from
      the bottom to the top, and the descent, where the pedal displacement occurs from the top to
      the bottom, with greater power.

      Cycling exercise can be used for muscle activation and strengthening, also performed
      rhythmically and alternately between the pedals. In the descending phase, there is activation
      of the muscles: gluteus maximus, gluteus medius, vastus intermedius, vastus lateralis, vastus
      medialis, rectus femoris, gastrocnemius and soleus, with hip and knee extension. In the
      so-called ascending phase, the ilipsoas, hamstrings and tibialis anterior muscles are
      activated with consequent flexion of the hip and knee.

      Electromyography is a representation of the motor control of the muscular system through the
      placement of electrodes in the motor units and capture of electrical activity. The
      electromyographic analysis is used not only to verify muscle activity, but also to determine
      the periods of coactivation of agonist and antagonist muscles, and can assess activity for
      function, contraction and learning.

      The electromyography signal originates from the electrical activity of the endplate. Thus,
      the electromyographic signal is generated by the union of the activation potentials of the
      motor units that are recruited concomitantly, resulting in the interference tracing.

      Electromyographic biofeedback is an electronic instrument that provides information
      (feedback) to an individual about a physiological function or response.
    

Intervention name(s): muscle activation of the vastus lateralis, vastus medialis, gluteus medius, tibialis anterior, rectus abdominis and paravertebral muscles
Intervention type(s): Diagnostic Test
Intervention description(s): understand the pattern of muscle activation during modalities used in this study with the selected population, it becomes extremely important, allowing the quantification of muscle functions and, therefore, prescribing exercises more adequately to achieve therapeutic goals.
Observational model: Case-Crossover
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Clinical diagnosis of spinal cord injury for at least 6 months, aged between 17 and 60
        years, spastic or flaccid, of both sexes.
      
Keywords: spinal cord injuries; Motor Activity; Electromyography; Physical Therapy