Biology Reference
In-Depth Information
extent of muscle reinnervation following peripheral nerve injury. Furthermore, treadmill
running has the ability to increase the release of neurotrophins and growth factors in
the spinal cord, the injured nerve, and reinnervating muscles. Treadmill running also
seems to prevent the development of neuropathic pain and allodynia as a result of
peripheral nerve damage. In addition, physical exercise, even if performed for a short
period of time, exerts positive conditioning effects in neuroregeneration capacity,
improving the acute response to peripheral nerve insults. Some of these effects can also
be obtained with passive exercise or manual stimulation. In humans, however, evidence
demonstrating a positive effect of exercise on nerve regeneration is at best poor.
1. INTRODUCTION
Despite advances in treatment, traumatic peripheral nerve injuries
remain an important cause of chronic disability and pain with a negative
impact in health-related quality of life (
Ciaramitaro et al., 2010
). The health
and social burden of peripheral nervous system (PNS) trauma is made worse
by its higher prevalence in young adults, as a result of traffic and sport-related
accidents (
Lad, Nathan, Schubert, & Boakye, 2010
).
Several neurobiological mechanisms underlying PNS regenerations
and reinnervation of target organs have been identified in the past years
(
de Ruiter et al., 2008; Gordon, Tyreman, & Raji, 2011; Ijkema-Paassen,
Meek, & Gramsbergen, 2002
). Reinnervation and functional recovery suc-
cess following peripheral nerve injury are affected by the distance from the
site of injury to the denervated targets, which determines the duration of
muscle denervation (
Kobayashi et al., 1997
), sluggish and staggered axonal
elongation past the injury site (
Al-Majed, Neumann, Brushart, & Gordon,
2000; Brushart, 1990
), loss of regeneration support by the distal nerve and by
denervated Schwann cells (
Gordon et al., 2011
), inaccurate reinnervation of
the targets (
Angelov et al., 2007; de Ruiter et al., 2008
), and severe muscle
atrophy and muscle fiber degeneration (
Dedkov, Kostrominova, Borisov, &
Carlson, 2001; Gordon et al., 2011
). Neuronal cell death is possibly another
potential factor compromising functional outcome after traumatic PNS
injury, particularly if the injury is near the central nervous system (CNS)
and involves sensory neurons (
Abrams & Widenfalk, 2005
).
Physical exercise, by means of voluntary or forced locomotion, is
one of several possible strategies to enhance peripheral nerve regenera-
tion and improve target reinnervation (
English, Wilhelm, & Sabatier,
2011; Udina, Cobianchi, Allodi, & Navarro, 2011
). Although therapeutic
exercise stands as a common practice in the rehabilitation of PNS lesions
