Effect of endurance training on muscle fat metabolism during prolonged exercise:: Agreements and disagreements

The rate of lipolysis in the adipose tissue is influenced by a number of factors, the most important being the level of neurohormonal stimulation or inhibition1-7 and the rate of adipose blood flow.7-11 During exercise, plasma epinephrine and norepinephrine are elevated several times above resting values.3,4,6 The modulatory effects of physiologic catecholamines on fat cell function involve various adrenergic receptor subtypes,12 which are lipolytic through ÃZ²1-, ÃZ²2-, and ÃZ²3-adrenergic receptors and anti-lipolytic through the ÃZ±2-adrenergic receptor.1,7,13-16 The effect of endurance training on the ability to mobilize endogenous TG is controversial because of conflicting results originating from different investigations. [...]longitudinal training studies combining in vivo microdialysis technique (which allows measurement of extracellular concentrations of various substances that diffuse from the interstitium of adipose tissue in different anatomic locations) with other recent techniques (tracer technology, dual-energy x-ray absorptiometry, measurement of adrenergic receptor subtypes, measurement of hormonal and enzymatic responses to training, measurement of sympathetic nerve activity, and measurement of local blood flow) may clarify the different research results cited in the literature.