Acute effect of Fatmax exercise on the metabolism in overweight and nonoverweight girls

Enhancing cardiometabolic health through physical activity and breakfast manipulations in children and adolescents: good for humans, good for the planet

The human health benefits of cardiometabolic disease prevention can be accompanied by planetary co-benefits. Focusing efforts towards young people, including children and adolescents, is conducive to disease prevention. In the context of cardiometabolic disease prevention, this review paper critically summarises the available literature on the acute cardiometabolic responses to physical activity and breakfast manipulations among young people. Given the seriousness of global climate change, which will disproportionally affect our younger generations, this review paper offers new insights into the inherent interactions between child-adolescent behaviour and cardiometabolic health from an environmental sustainability perspective to aid climate change mitigation efforts, including exploring future research avenues. A growing evidence base suggests acute moderate- to high-intensity exercise bouts can attenuate postprandial plasma glucose, insulin and triacylglycerol concentrations for up to 24-48 h in young people. Whether accumulating physical activity throughout the day with short, frequent bouts promotes cardiometabolic risk marker attenuations is unclear. Breakfast consumption may enhance free-living physical activity and reduce glycaemic responses to subsequent meals for a possible additive impact. If repeated habitually, attenuations in these cardiometabolic risk factors would be conducive to disease prevention, reducing the greenhouse gas emissions associated with disease diagnosis and treatment. To progress current understanding with high public health and planetary relevance, research among samples of 'at risk' young people that span cellular-level responses to ecologically valid settings and address human and planetary health co-benefits is needed. Indeed, certain physical activity opportunities, such as active travel to school, offer important direct co-benefits to humans and planetary health.

Acute Cardiometabolic and Exercise Responses to Breakfast Omission Versus Breakfast Consumption in Adolescent Girls: A Randomised Crossover Trial

Girls often begin to skip breakfast during adolescence. This study compared the acute effect of breakfast omission versus consumption on cardiometabolic risk markers and perceived appetite and mood during rest and/or exercise in adolescent girls classified as habitual breakfast consumers. Girls (aged 13.2 ± 0.7 years) completed two 5.5 h conditions in a randomised crossover design: breakfast omission (BO) and standardised breakfast consumption (BC). A standardised lunch was provided at 3 h. Incremental cycling exercise was performed at 5 h. Blood and expired gas samples were taken at regular intervals. Whilst pre-lunch plasma glucose, insulin, and Metabolic Load Index incremental area under the curve (IAUC) were significantly lower in BO versus BC, post-lunch differences were reversed and larger in magnitude. Peak plasma glucose and insulin were significantly higher in BO versus BC. Pre-lunch perceived fullness and hunger were significantly lower and higher, respectively, in BO versus BC. Perceived energy and concentration were lower, and tiredness was higher, in BO versus BC. Exercise peak fat oxidation and Fatmax were unaffected. The lower physical activity enjoyment in BO versus BC approached significance. To conclude, acutely omitting breakfast adversely affects cardiometabolic risk markers and exercise enjoyment among adolescent girls who habitually consume breakfast.

The impact of glycaemic load on cognitive performance: A meta-analysis and guiding principles for future research

The effect of breakfast glycaemic load (GL) on cognition was systematically examined. Randomised and non-randomised controlled trials were identified using PubMed, Scopus, and Cochrane Library (up to May 2022). 15 studies involving adults (aged 20 - 80 years) were included. Studies had a low risk, or some concerns, of bias. A random-effects meta-analysis model revealed no effect of GL on cognition up to 119 min post-consumption. However, after 120 min, immediate episodic memory scores were better following a low-GL compared to a high-GL (SMD = 0.16, 95% confidence interval [CI] = -0.00 to 0.32, p = 0.05, I2 = 5%). Subgroup analyses indicated that the benefit was greater in younger adults (<35 years) and those with better GT. A qualitative synthesis of 16 studies involving children and adolescents (aged 5 - 17 years) suggested that a low-GL breakfast may also benefit episodic memory and attention after 120 min. Methodological practises were identified which could explain a failure to detect benefits in some studies. Consequently, guiding principles were developed to optimise future study design.

Fat Oxidation Rates in Professional Soccer Players

PURPOSE

Large interindividual variation exists in maximal fat oxidation (MFO) rates and the exercise intensity at which it occurs (FATMAX). However, there are no data describing the shape of the fat oxidation curve or if individual differences exist when tested on separate occasions. Furthermore, there are limited data on fat metabolism in professional team sport athletes. Therefore, the aim of this study was to test-retest the concavity (shape) and intercept (height) of fat oxidation curves within a group of professional soccer players.

METHOD

On two occasions, 16 professional male soccer players completed a graded exercise test in a fasted state (≥5 h). Rates of fat oxidation were determined using indirect calorimetry. Maximal oxygen uptake (V˙O2max) was measured to calculate FATMAX (%V˙O2max). The shape of the fat oxidation curves were modeled on an individual basis using third-degree polynomial. Test-by-test differences, in the shape and vertical shift of the fat oxidation curves, were established to assess within-individual variability.

RESULTS

Average absolute MFO was 0.69 ± 0.15 g·min (range, 0.45-0.99 g·min). On a group level, no significant differences were found in MFO between the two tests. No differences were found (P > 0.05) in the shape of the fat oxidation curves in 13 of 16 players (test 1 vs test 2). There were also no differences (P > 0.05) in the vertical shift of the fat oxidation curves in 10 players.

CONCLUSIONS

In general, the shape of the fat oxidation curve does not change within an individual; however, the vertical shift is more susceptible to change, which may be due to training status and body composition. Understanding a player's metabolism may be of value to practitioners working within sport, with regard to personalizing nutrition strategies.

Trp64Arg polymorphism of the ADRB3 gene associated with maximal fat oxidation and LDL-C levels in non-obese adolescents

OBJECTIVE

To analyze the association between the Trp64Arg polymorphism of the ADRB3 gene, maximal fat oxidation rates and the lipid profile levels in non-obese adolescents.

METHODS

72 schoolchildren, of both genders, aged between 11 and 17 years, participated in the study. The anthropometric and body composition variables, in addition to total cholesterol, HDL-c, LDL-c, triglycerides, insulin, and basal glycemia, were evaluated. The sample was divided into two groups according to the presence or absence of the polymorphism: non-carriers of the Arg64 allele, i.e., homozygous (Trp64Trp: n=54), and carriers of the Arg64 allele (Trp64Arg+Arg64Arg: n=18), in which the frequency of the Arg64 allele was 15.2%. The maximal oxygen uptake and peak of oxygen uptake during exercise were obtained through the symptom-limited, submaximal treadmill test. Maximal fat oxidation was determined according to the ventilatory ratio proposed in Lusk's table.

RESULTS

Adolescents carrying the less frequent allele (Trp64Arg and Arg64Arg) had higher LDL-c levels (p=0.031) and lower maximal fat oxidation rates (p=0.038) when compared with non-carriers (Trp64Trp).

CONCLUSIONS

Although the physiological processes related to lipolysis and lipid metabolism are complex, the presence of the Arg 64 allele was associated with lower rates of FATMAX during aerobic exercise, as well as with higher levels of LDL-c in adolescents.

A single exercise session increases insulin sensitivity in normal weight and overweight/obese adolescents

We measured the effect of an aerobic exercise session on postprandial glucose control in adolescents with habitually low-physical activity. The goal was to determine if the acute or residual response of exercise was altered in people who are overweight/obese (OW/Ob). Eleven normal weight, body mass index (NW, BMI = 48 ± 13 percentile) and 12 OW/Ob (BMI = 91 ± 5 percentile) participants completed 3 trials. In the no exercise (No Ex) trial, participants rested quietly before and after consuming a test meal. In the other 2 trials, a 45-minute aerobic exercise session was performed either 17-hour (Prior Day Ex) or 40 minutes (Same Day Ex) before the test meal. On all trials, the OW/Ob group had higher fasting glucose (~6%) and insulin (~66%), and lower insulin sensitivity (~9%) than the NW group. The Same Day Ex and Prior Day Ex trials resulted in reduced area under the curve for glucose (6% on both trials, P < .01) and insulin (15% and 13%, respectively, P < .03), and increased insulin sensitivity (8% and 6%, respectively, P < .01). The magnitudes of those effects did not differ between the NW and OW/Ob groups. Plasma fatty acids declined and carbohydrate oxidation increased after the meal, but did not differ among trials or groups. The results demonstrate that moderate intensity aerobic exercise increases insulin sensitivity in NW and OW/Ob adolescents and that the beneficial effects of exercise last up to 17 hours. The acute impact of exercise on metabolic health in adolescents is not impaired in overweight/obese participants.

A single bout of high-intensity interval exercise and work-matched moderate-intensity exercise has minimal effect on glucose tolerance and insulin sensitivity in 7- to 10-year-old boys

The purpose of this study was to assess the acute effect of high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on glucose tolerance, insulin sensitivity and fat oxidation in young boys. Eleven boys (8.8 ± 0.8 y) completed three conditions: 1) HIIE; 2) work-matched MIE; and 3) rest (CON) followed by an oral glucose tolerance test (OGTT) to determine glucose tolerance and insulin sensitivity (Cederholm index). Fat oxidation was measured following the OGTT using indirect calorimetry. There was no effect for condition on plasma [glucose] and [insulin] area under the curve (AUC) responses following the OGTT (P > 0.09). However, there was a "trend" for a condition effect for insulin sensitivity with a small increase after HIIE (P = 0.04, ES = 0.28, 9.7%) and MIE (P = 0.07, ES = 0.21, 6.5%) compared to CON. There was an increase in fat oxidation AUC following HIIE (P = 0.008, ES = 0.79, 38.9%) compared to CON, but with no differences between MIE and CON and HIIE and MIE (P > 0.13). In conclusion, 7- to 10-year-old boys may have limited scope to improve insulin sensitivity and glucose tolerance after a single bout of HIIE and MIE. However, fat oxidation is augmented after HIIE but not MIE.

Maximal Fat Oxidation Rate during Exercise in Korean Women with Type 2 Diabetes Mellitus

BACKGROUND

The purpose of this study was to determine the appropriate exercise intensity associated with maximum fat oxidation, improvement of body composition, and metabolic status in Korean women with type 2 diabetes mellitus (T2DM).

METHODS

The study included a T2DM group (12 women) and a control group (12 women). The groups were matched in age and body mass index. The subjects performed a graded exercise test on a cycle ergometer to measure their maximal fat oxidation (Fatmax). We also measured their body composition, metabolic profiles, and mitochondrial DNA (mtDNA).

RESULTS

The exercise intensity for Fatmax was significantly lower in the T2DM group (34.19% maximal oxygen uptake [VO2 max]) than the control group (51.80% VO2 max). Additionally, the rate of fat oxidation during exercise (P<0.05) and mtDNA (P<0.05) were significantly lower in the T2DM group than the control group. The VO2 max level (P<0.001) and the insulin level (P<0.05) were positively correlated with the rate of fat oxidation.

CONCLUSION

The results of this study suggest lower exercise intensity that achieves Fatmax is recommended for improving fat oxidation and enhancing fitness levels in Korean women with T2DM. Our data could be useful when considering an exercise regimen to improve health and fitness.

High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys

OBJECTIVES

High-intensity interval exercise (HIIE) may offer a time efficient means to improve health outcomes compared to moderate-intensity exercise (MIE). This study examined the acute effect of HIIE compared to a work-matched bout of MIE on glucose tolerance, insulin sensitivity (IS), resting fat oxidation and exercise enjoyment in adolescent boys.

DESIGN

Within-measures design with counterbalanced experimental conditions.

METHODS

Nine boys (14.2 ± 0.4 years) completed three conditions on separate days in a counterbalanced order: (1) HIIE; (2) work matched MIE, both on a cycle ergometer; and (3) rest (CON). An oral glucose tolerance test (OGTT) was performed after exercise or rest and the area under curve (AUC) responses for plasma [glucose] and [insulin] were calculated, and IS estimated (Cederholm index). Energy expenditure and fat oxidation were measured following the OGTT using indirect calorimetry. Exercise enjoyment was assessed using the Physical Activity Enjoyment Scale.

RESULTS

The incremental AUC (iAUC) for plasma [glucose] was reduced following both MIE (-23.9%, P = 0.013, effect size [ES] = -0.64) and HIIE (-28.9%, P=0.008, ES = -0.84) compared to CON. The iAUC for plasma [insulin] was lower for HIIE (-24.2%, P = 0.021, ES = -0.71) and MIE (-29.1%, P = 0.012, ES = -0.79) compared to CON. IS increased by 11.2% after HIIE (P = 0.03, ES = 0.76) and 8.4% after MIE (P = 0.10, ES = 0.58). There was a trend for an increase in fat oxidation following HIIE (P = 0.097, ES = 0.70). Both HIIE and MIE were rated as equally enjoyable (P > 0.05, ES < 0.01).

CONCLUSION

A single bout of time efficient HIIE is an effective alternative to MIE for improving glucose tolerance and IS in adolescent boys immediately after exercise.

Postprandial improvement in insulin sensitivity after a single exercise session in adolescents with low aerobic fitness and physical activity

The purpose of this study was to determine the acute and residual impact of a single exercise bout on meal glucose control in adolescents with habitually low physical activity. Twelve adolescents (seven females/five males, 14 ± 2 yr) completed three trials. One trial [No Exercise (No Ex)] was completed after refraining from vigorous activity for ≥ 3 d. On the other two trials, a 45-min aerobic exercise bout at 75% peak heart rate was performed either 17-h Prior Day Exercise (Prior Day Ex) trial or 1-h Same Day Exercise (Same Day Ex) trial before consuming the test meal (2803 kJ, 45/40/15% energy as carbohydrate/fat/protein, respectively). Compared to No Ex, insulin sensitivity (SI) (minimal model analysis) was increased by 45% (p < 0.03) and 78% (p < 0.01) on the Prior Day Ex and Same Day Ex trials, respectively. This improvement in glucose control was supported by corresponding reductions in the net area under the curve for glucose, insulin, and c-peptide, although there was no change in postprandial suppression of fatty acids. These results show that SI is improved with a single bout of moderate intensity exercise in adolescents with habitually low physical activity and that the residual beneficial effect of exercise lasts at least 17 h. This finding highlights the plasticity of exercise responses in youth and the importance of daily exercise for metabolic health.