Differences on oxygenm consumption between individuals with spastic diplegia able-bodied peers: a pilot study

 

Introduction

It is acknowledged that children and adolescents with spastic diplegia (SD) and with cerebral palsy (CP) generally have to maintain higher levels of physical fitness than the general population to offset the decline in function that arises, since there has been observed that their movement condition, like the ability to walk, tends to deteriorate from about the second decade due to either the combination of puberty and disease status (i.e decreased strength, endurance) or the changes related to their condition (reduced mobility, spasticity, contractures, pain) (Bar-Or et al., 1976; Rimmer, 2001). The purpose of this study was to compare the oxygen consumption (VO₂) between individuals with SD and their able-bodied peers. In addition to find out if there are any differences between them and the possible physiological mechanisms that cause this difference.

Methods

 7 young individuals with SD, (5 girls and 2 boys, Μ=15,86 ± 1,46 yrs) and 7 able-bodied peers (5 girls and 2 boys, Μ=14,71 ± 0,48 yrs) participated in the study. The exercise tests were performed on an arm ergometer (Monark - Rehab. Trainer 881E) at a pedaling rate of 50rpm indicated by a metronome. During exercise tests, expired gas was analyzed continuously with an open-circuit system (Jaeger EOS-Sprint Oxygen Analyzer, Wurzburg, Germany). Heart rate was monitored continuously by means of an electrocardiograph. Blood samples for determination of lactate concentration were drawn from a fingertip after maximal exercise. The determination was made by means of reflectance photometry (Accusport System, Boehringer, Mannheim, Germany). In the statistical analysis, a non-parametric test (One-sample Kolmogorov-Smirnov Test) was initially used to confirm the normal allocation of the subjects, and to allow the use of a parametric test (Independent Samples T-test).

Results

The parametric test revealed that there was a statistically significant difference in VO₂  (34.2%) between young individuals with SD and their able-bodied peers. On the contrary, the HR, the BMI and the blood lactate accumulation during maximal exercise did not differ significantly between the two groups.  

Discussion/Conclusions

 The results seem to be in agreement with other studies (Bar-Or et al., 1976; Berg-Emons van den et al., 1988; Lundberg, 1978; 1984; Lundberg et al., 1967) which have demonstrated a difference of 10-50% in VO₂. One possible physiological mechanism for the lower VO₂ values seen in individuals with SD, could be their lower breathing efficiency as evidenced by higher ventilatory equivalent values for oxygen. High muscle tone, which reduces venous return and inhibits muscle lactate clearance during exercise and thereby increases local muscle fatigue, is another mechanism that may contribute to lower VO₂max values. In addition, involuntary limb movements affect submaximal oxygen consumption. Conclusively, this study provides evidence of reduced VO₂ in individuals with SD compared with their able-bodied peers.

 

References

[1]. Bar-Or O. et al. (1976).  Med Sci Sports, 8,157-161

[2]. Berg-Emons van den R.G. et al. (1998). Intern J Rehab Research, 21,179-194

[3]. Lundberg A. (1984). Dev Med Child Neurol, 26, 328-334

[4]. Lundberg A. (1978). Dev Med Child Neurol, 20, 205-210

[5]. Lundberg A. et al. (1967). Acta Paediatric Scand, 56,182-188

[6]. Rimmer J. H. (2001). Dev Med Child Neurol 43, 208-212