Elsevier

Metabolism

Volume 65, Issue 4, April 2016, Pages 496-506
Metabolism

Clinical Science
Energy replacement diminishes the effect of exercise on postprandial lipemia in boys

https://doi.org/10.1016/j.metabol.2015.12.001Get rights and content

Abstract

Purpose

Acute bouts of exercise reduce postprandial triacylglycerol concentrations ([TAG]) in healthy boys and girls; however, it is not known whether this effect is mediated by the energy deficit. This study examined whether the exercise-induced reduction in postprandial [TAG] persists after immediate dietary replacement of the exercise energy expenditure (EE).

Methods

Eighteen healthy 11- to 13-year-old boys (mean (SD): body mass 41.3 (8.4) kg; peak oxygen uptake (V̇O2) 55 (5) mL·kg 1·min 1) completed three, 2-day conditions in a within-measures, crossover design separated by 14 days. On day 1, participants rested (CON), exercised at 60% peak V̇O2 inducing a net EE of 32 kJ·kg 1 body mass (EX-DEF) or completed the same exercise with the net EE replaced immediately (EX-REP). On day 2, capillary blood samples were taken in the fasted state and at pre-determined intervals throughout the 6.5 h postprandial period. A standardised breakfast and lunch meal were consumed immediately and 4 h, respectively, after the fasting sample.

Results

Based on ratios of the geometric means (95% confidence intervals (CI) for ratios), EX-DEF fasting [TAG] was 19% and 15% lower than CON (− 32 to − 4%, ES = 1.15, P = 0.02) and EX-REP (− 29 to 0%, ES = 0.91, P = 0.05) respectively; CON and EX-REP were similar (− 4%; P = 0.59). The EX-DEF total area under the [TAG] versus time curve was 15% and 16% lower than CON (− 27 to 0%, ES = 0.55, P = 0.05) and EX-REP (− 29 to − 2%, ES = 0.62, P = 0.03) respectively; CON and EX-REP were not different (2%; − 13 to 20%, P = 0.80).

Conclusion

Immediate replacement of the exercise-induced energy deficit negates the reduction in postprandial [TAG] in boys; this highlights the importance of maintaining a negative energy balance immediately post-exercise to maximise the metabolic health benefits of exercise.

Introduction

Elevated postprandial triacylglycerol concentrations ([TAG]) are predisposed to the development and progression of atherosclerosis [1], and independently predict future cardiovascular disease risk in adults [2]. Although the clinical manifestations of atherosclerotic disease emerge in adulthood typically, the paediatric origins of atherosclerosis are well established [3]. Furthermore, childhood fasting [TAG] predicts young adult cardiovascular disease risk [4]. Most people spend the majority of waking hours in a postprandial state, resulting in extended periods of elevated postprandial [TAG]. Considering cardiovascular disease remains the leading cause of mortality in the United Kingdom [5], prevention by targeting modifiable risk factors is a high priority on the public health agenda. Therefore, lifestyle modifications that reduce postprandial [TAG] from a young age may delay precursors of atherosclerotic disease leading to important long-term metabolic health benefits [3].

Previous research highlights the potency of acute moderate- to vigorous-intensity exercise interventions completed up to 18 h before a standardised meal to reduce postprandial [TAG] in adults [6] and young people [7]. Furthermore, acute exercise has been shown to increase resting fat oxidation in the postprandial period in adults [8], [9]. Considering energy status can have profound effects on metabolism [10], the acute exercise-evoked changes in postprandial TAG metabolism may be mediated by the associated energy deficit. In this regard, an exercise-induced energy deficit appears more potent than an isoenergetic diet-induced deficit in reducing postprandial [TAG] in girls [11] and women [12], [13]. Moreover, replacement of the exercise-induced energy deficit in adults diminishes or even eliminates the reduction in postprandial [TAG] [8], [14], [15], [16], and concomitant increase in resting whole-body fat oxidation [8], [16]. However, the effect of replacing the exercise-induced energy deficit on postprandial [TAG] and resting whole-body fat oxidation has not been investigated in young people. Metabolic and hormonal responses to exercise differ considerably between men and boys [17], [18], and hormonal changes occurring during pubertal development may influence [TAG] [19]. Consequently, it is important to address whether the acute exercise-induced reduction in postprandial [TAG] and increase in resting whole-body fat oxidation persist after replacing the exercise energy expenditure (EE) in boys.

Therefore, the aim of the present study was to examine the effect of acute moderate-intensity exercise, with and without immediate dietary replacement of the exercise-induced energy deficit, on postprandial [TAG] and resting whole-body fat oxidation in healthy, recreationally active boys.

Section snippets

Participants

Eighteen boys aged 11.4 to 13.2 years volunteered to participate in this study. The study was approved by the University Ethical Advisory Committee. Written assent was obtained from each participant and written informed consent by a parent or guardian. Participants completed a health screen questionnaire which confirmed they were all in good general health, had no history of medical conditions that may compromise participation in the study and were not taking any medications or dietary

Dietary Intake

Energy and macronutrient intakes were not different between the conditions on the pre-intervention day (P  0.25). Average daily energy intake was 7.9 (1.8) MJ, and dietary intake of protein, carbohydrate and fat was 69.2 (21.7) g, 254 (62) g and 66.6 (24.5) g respectively. Energy and absolute protein, carbohydrate and fat intake on the intervention day were higher in EX-REP compared with CON and EX-DEF (effect size (ES) = 0.60 to 1.22, P < 0.001); CON and EX-DEF were similar (P  0.35) (Table 2). However,

Discussion

The primary finding from the present study was that immediate replacement of the acute exercise-induced energy deficit negates the reduction in fasting and postprandial [TAG] in boys. Furthermore, an exercise-induced energy deficit was required to promote an increase in postprandial whole-body fat oxidation. Therefore, judicious use of energy replacement practises immediately post-exercise may be required in boys to maximise the metabolic health benefits of exercise. To our knowledge, this is

Conclusion

In conclusion, the findings of the present study demonstrate that immediate replacement of the acute exercise-induced energy deficit eliminates the reduction in fasting and postprandial [TAG] the following day in healthy boys. In addition, meaningful increases in postprandial whole-body fat oxidation appear dependent on the presence of an energy deficit. Consequently, maintaining a negative energy balance immediately after exercise may be required to maximise the beneficial effect of exercise

Author Contributions

AET, LAB, and KT designed the study; AET conducted the research; AET and KT analysed and interpreted the data; AET wrote the manuscript; LAB and KT provided critical revisions to the manuscript; AET, LAB and KT read and approved the final manuscript.

Funding

The research was supported by the National Institute for Health Research (NIHR) Diet, Lifestyle & Physical Activity Biomedical Research Unit based at University Hospitals of Leicester and Loughborough University. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

Disclosure Statement

The authors report no conflict of interest.

Acknowledgements

We thank Woodbrook Vale School in Loughborough for their support throughout this research. We also thank the participants and their parents for their commitment throughout the study.

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