Exercise Effects on Adipose Tissue Postprandial Lipolysis and Blood Flow in Children

Abstract

Poor suppression of lipolysis and blunted increase in blood flow after meal ingestion in obese adults may indicate resistance to the antilipolytic action of insulin. Exercise may be used to normalize lipolytic responses to food intake by increasing insulin sensitivity.

Purpose: To determine if acute bouts of aerobic exercise and/or excise training alter lipolytic and blood flow responses to food intake in lean (LN) and obese (OB) children.

Methods: Sixty-five children (9-11 yr) were randomized into acute exercise (EX: 16 LN and 28 OB) or control (CON: 9 LN and 12 OB) groups that exercised (EX), or rested (CON) between standardized breakfast and lunch. Microdialysis probes were inserted into the subcutaneous abdominal adipose tissue to monitor interstitial glycerol (lipolysis) and blood flow. Changes in interstitial glycerol and nutritive flow were calculated from dialysate samples before and after each meal. A subgroup (OB = 15 and LN = 9) from the acute exercise group underwent 16 wk of aerobic exercise training.

Results: Poor suppression of lipolysis and a blunted increase in adipose tissue nutritive blood flow in response to breakfast was associated with BMI percentile (r = 0.3, P < 0.05). These responses were normalized at lunch in the OB in the EX (P < 0.05), but not in OB in the CON. Sixteen weeks of exercise training did not improve meal-induced blood flow and marginally altered the antilipolytic response to the two meals (P = 0.06).

Conclusions: Daily bouts of acute aerobic exercise should be used to improve the antilipolytic and nutritive blood flow response to a subsequent meal in obese children.

Figure 1

Interstitial glycerol in the subcutaneous abdominal adipose tissue of LN and OB children in the acute exercise group (1A) and control group (1B) over the course of an 8-h period from the morning to midafternoon. Two-way (time by obesity status) repeated measures ANOVA were separately performed in acute EX and acute CON. § p<0.05 for main effect of time; ‡ p<0.05 for main effect of obesity EX - acute exercise group; CON – control group.

Figure 2

Percent change in interstitial glycerol in response to breakfast and lunch in LN and OB children in the acute exercise group (2A) and control group (2B). Two-way (time by obesity status) repeated measures ANOVA were separately performed in acute EX and acute CON.* p<0.05 for meal by obesity interaction; § p<0.05 for main effect of time. EX - acute exercise group; CON - control group.

Figure 3

Ethanol O:I ratio (inversely related to nutritive blood flow) of LN and OB children in the acute exercise group (3A) and control group (3B) over the course of an 8-h period from the morning to midafternoon. Dialysate samples were collected from the subcutaneous abdominal adipose tissue and analyzed for ethanol concentration. Data are presented as the ethanol O:I ratio, which is inversely related to nutritive blood flow. ‡ p<0.05 for main effect of obesity; § p<0.05 for main effect of time. EX - acute exercise group; CON - control group.

Figure 4

Percent change in ethanol O:I ratio in response to breakfast and lunch in LN and OB children in the acute exercise group (4A) and control group (4B). Two-way (time by obesity status) repeated measures ANOVA were separately performed in acute EX and acute CON. * P < 0.05 meal by obesity interaction. EX - acute exercise group; CON – control group.

Figure 5

Interstitial glycerol in the subcutaneous abdominal adipose tissue of LN and OB children before exercise training (5A) and after 16-week aerobic exercise training (5B), and ethanol O:I ratio (inversely related to nutritive blood flow) of LN and OB children before exercise training (5C) and after 16-week aerobic exercise training (5D) over the course of an 8-h period from the morning to midafternoon. Three-way (intervention by time by obesity status) repeated measures ANOVA were performed in the training group in lean and obese children before and after aerobic training intervention. § p<0.05 for main effect of time; ‡ p<0.05 for main effect of obesity. Pre-train – before exercise training; Post-train – after exercise training.