THE EFFECT OF 13 WEEKS OF RUNNING TRAINING FOLLOWED BY 9 D OF DETRAINING ON POSTPRANDIAL LIPEMIA

The present study examined the influence of training, followed by a sh ort period of detraining, on postprandial Lipaemia. Fourteen normolipi daemic, recreationally active young adults aged 18-31 years participat ed, in two self-selected groups: three men and five women (BMI 21.7-27 .6 kg/m(2)) completed 13 weeks of running training, after which they r efrained from exercise for 9 d; three men and three women (BMI 21.5-25 .6 kg/m(2)) maintained their usual lifestyle. Oral fat tolerance tests were conducted at baseline and again 15 h, 60 h and 9 d after the run ners' last braining session. Blood samples were drawn after an overnig ht fast and at intervals for 6 h after consumption of a high-fat meal (1.2 g fat, 1.4g carbohydrate, 70.6kJ energy/kg body mass). Heparin wa s then administered (100 IU/kg) and a further blood sample was drawn f or measurement of plasma lipoprotein Lipase (EC 3.1.1.34; LPL) activit y. Endurance fitness improved in runners, relative to controls (maxima l O-2 uptake +3.2 (SE 1.1) ml/kg per min v. -1.3 (SE 1.2) ml/kg per mi n; P < 0.05). In the absence of the acute effect of exercise, i.e. 60 h after the last training session, there was no effect of training on either postprandial lipaemia or on post-heparin LPL activity. However, changes during 9 d of detraining in both these variables differed sig nificantly between groups; after 2 d without exercise (60 h test), the runners' lipaemic response was 37% higher than it was the morning aft er their last training session (15 h test; runners v. controls P < 0.0 5), with a reciprocal decrease in post-heparin LPL activity (P < 0.01) . These findings suggest that improved fitness does not necessarily co nfer an effect on postprandial lipaemia above that attributable to a s ingle session of exercise.