Compressed air massage causes capillary dilation in untraumatised skeletal muscle: a morphometric and ultrastructural study

Abstract

Objectives

Massage is thought to encourage the healing of soft tissue injuries by improving blood flow to the damaged region. This study used light microscopy, transmission electron microscopy and morphometry to determine whether: (a) compressed air massage causes capillary vasodilation; (b) such dilation persists for an extended period of time; and (c) the treatment damages capillaries.

Design

Animal model involving 12 New Zealand white rabbits.

Setting

Electron microscopy unit of the University of KwaZulu-Natal, South Africa.

Interventions

The rabbits were anaesthetised and treated for 15 minutes using compressed air massage at 1bar (100kPa).

Main outcome measures

Biopsies were taken from the treated vastus lateralis within 10 minutes (n=4), 24 hours (n=4) and 6 days (n=4) after treatment and control biopsies were taken from the vastus lateralis of the untreated limb. The samples were stained with toluidine blue for light microscopy, and the external cross-sectional area of at least 60 capillaries was measured from each specimen using image analysis software. Ultra-thin sections were prepared for transmission electron microscopy from biopsies taken from control and treated limbs within 10 minutes (n=2) and 24 hours (n=2) after treatment. At least 25 capillaries were collected from each specimen. Endothelial cell thickness and the external and luminal diameters were measured and cross-sectional areas were calculated.

Results

On light microscopy, mean external cross-sectional diameter had increased by 8% immediately after treatment, from 4.96±1.09μm (95% confidence interval: 4.85–5.08) to 5.33±1.21μm (95% confidence interval: 5.22–5.45) (P<0.001), and by 11% 24 hours later, from 5.00±1.22μm (95% confidence interval: 4.87–5.13) to 5.52±1.22μm (95% confidence interval: 5.37–5.67) (P<0.001), returning to normal at 6 days. On electron microscopy, luminal cross-sectional area had increased by 35% immediately after treatment, from 20.29±9.07μm2 (95% confidence interval: 19.37–21.2) to 23.50±11.83μm2 (95% confidence interval: 22.35–24.66) (P<0.05), and remained 30% larger, 24 hours later, from 20.77±10.88μm2 (95% confidence interval: 19.60–21.95) to 25.66±16.03μm2 (95% confidence interval: 23.99–27.33) (P<0.05). While capillaries were larger, endothelial cell thickness was reduced in all post-massage specimens, suggesting vasodilation. No pathomorphology was noted in any capillary apart from mild oedema in one specimen.

Conclusions

Compressed air massage of muscle causes vasodilation of skeletal muscle capillaries and this persists for at least 24 hours after treatment.

Citation

Compressed air massage causes capillary dilation in untraumatised skeletal muscle: a morphometric and ultrastructural study
M.A. Gregory, M. Mars
Physiotherapy - September 2005 (Vol. 91, Issue 3, Pages 131-137, DOI: 10.1016/j.physio.2004.11.007)