Role of cocontraction in the O2 cost of walking in children with cerebral palsy

Abstract

91 +/- 14 beats.min-1). Thigh and lower leg muscle cocontraction accounted for 51.4% and 42.8%, respectively, of the variability in VO2 for the subjects with CP at 3 km.h-1. These results suggest that cocontraction is a major factor responsible for the higher energy cost of walking seen in children with CP.

Fatigue in cerebral palsy: A critical review

“…The increased demands on the muscle relative to its reduced overall capacity are reflected in reports of chronic fatigue in this population. In addition, several studies have documented an increased co-activation/co-contraction of agonist and antagonist muscles around the same joint in individuals with CP [3,12,13]. Small amounts of co-activation are normal; however, too much co-activation increases energy expenditure and as a result could lead to a faster rate of fatigue in both agonists and antagonists [12,14].…”

“…In addition, several studies have documented an increased co-activation/co-contraction of agonist and antagonist muscles around the same joint in individuals with CP [3,12,13]. Small amounts of co-activation are normal; however, too much co-activation increases energy expenditure and as a result could lead to a faster rate of fatigue in both agonists and antagonists [12,14]. It should be noted that one laboratory study has demonstrated higher hamstring co-contraction, spasticity and reduced hamstring strength to be predictive of fatigue resistance in the hamstring muscles [15].…”

“…In a laboratory setting, individuals with CP may appear less fatigable than the general population as a result of the inability of the descending tracts to fully transmit the signal to the muscles needed to produce a maximal contraction. However, functionally, a decreased efficiency of the descending signal from the motor cortex through damaged or abnormal projections to agonist and antagonist muscles around a joint can also lead to increased co-activation and increased energy expenditure, a potential cause of fatigue in individuals with CP [12], as discussed above.…”

Efficiency of work production by spastic muscles

“…In nine spastic CP children, Unnithan et al [25] analysed the relation between the energy consumption and co-contraction during walking at 3 km h À1 . Energy consumption increased in CP children in relation to thigh (r 2 = 51.4%) and shank co-contraction (r 2 = 42.8%).…”

Center of mass motion and the effects of ankle bracing on metabolic cost during submaximal walking trials

“…However, for individuals with neuromuscular disorders, like spastic cerebral palsy (CP), walking consumes a much higher percentage of available maximum energy output. 1 The result is that walking for individuals with CP is often a fatiguing activity, [1][2][3][4][5][6] with submaximal walking energy consumption as much as three times as large as that of healthy individuals. 1,3,5 A high correlation exists between this increased energy cost and the mechanical work performed in children with CP.…”