The studies described in this thesis were undertaken to examine the effects of exercise, particularly intermittent games activity, on fasting lipid and lipoprotein concentrations and postprandial lipaemia in adolescents and young adults. In order to be confident of the measurements made in the experimental studies described in this thesis it was necessary to investigate the reliability and criterion-validity of some of the techniques used in these studies. Therefore preliminary work was undertaken which compared the use of two different analysers (Reflotron and Cobas Mira Plus) to determine postprandial lipoprotein concentrations in venous and capillary blood. Triacylglycerol (TAG), glucose and total cholesterol concentrations measured from capillary whole blood using the Reflotron were on average 2% higher and 5% and 13.4% lower respectively, than those measured 10 venous plasma using the Cobas Mira Plus.