The influence of endurance and resistance exercise on muscle capillarization in the elderly: a review.

AIM: Ageing is one of many factors altering skeletal muscle. Conflicting results from previous studies guided this review to identify what has been found to date regarding microvascular adaptations in skeletal muscle as the result of ageing or inactivity, and endurance or resistance training interventions. Additionally, this review attempts to identify the variety of parameters for determining capillarization and discuss why these might be contributing to the conflicting results.
METHODS: Electronic database searches were conducted for full-length articles using relevant keywords related to ageing, muscle capillarization and exercise in all fields. Cross-sectional, longitudinal, training and review papers were included. Several studies on younger subject adaptation were also included for comparison.
RESULTS: Ageing and inactivity both result in regressive structural and functional changes to skeletal muscle capillarization. The rate and magnitude of decline is still unknown. Endurance training can positively effect structural changes to capillarity. There is conflicting evidence regarding the effects of resistance training. Training intensity may be an important factor. Biopsy sampling, histological staining and several measurement protocols may be providing inaccurate estimations of capillarity.
CONCLUSION: Part of the difficulty in determining the nature of these relationships has been the inconsistency in research conducted regarding age groups and controlling for past and present activity patterns. Further difficulties comparing across studies arise due to the variety of methods and parameters used to sample and analyse muscle tissue. Standardizing methodology will allow future research to yield more consistent results.