Clinical Capsules

Lower Exercise Intensity in Obese Boys

Obese adolescent boys have a limited capacity to metabolize fat by exercising at the recommended moderate intensity level, and might do better with lower-intensity activity, according to Dr. Gautier Zunquin, a sports medicine researcher at the University of the Littoral Opal Coast, Dunkirk, France, and associates.

To date, no studies have compared the rate of fat oxidation during exercise in obese children with rates in lean children using the same protocol. Dr. Zunquin and associates did so because they suspected current exercise guidelines should be altered for obese adolescents (Br. J. Sports Med. 2008 April 1 [doi:10.1136/bjsm.2007.044529]).

They calculated the fat oxidation rate in 13 lean and 17 obese 12-year-old boys, which allowed them “to construct a curve of fat oxidation vs. exercise intensity for each individual.” The maximal fat oxidation rate occurred at a lower level of exercise in the obese boys than in the lean boys. The lean boys metabolized the most fat exercising at 50%–60% of peak oxygen consumption, whereas the obese boys metabolized the most fat exercising at 30%–50% of peak oxygen consumption.

“Muscular modifications induced by obesity and being sedentary may partially explain the differences in fuel oxidation mechanisms,” wrote the authors. Differences between the two groups in hormonal changes during exercise, fatty-acid mobilization, and activation of α₂-adrenergic receptors might also play a role.

“Exercise intensity should be adapted to [children's] metabolic capacities during weight management programs,” they said.

Breast-Feeding and Type 2 Diabetes

Breast-fed babies may be protected against developing type 2 diabetes during childhood regardless of ethnicity, according to results from a study adjunct to the ongoing SEARCH for Diabetes in Youth investigation, by Elizabeth J. Mayer-Davis, Ph.D., of the University of South Carolina, Columbia, and her colleagues.

Their case-control study, conducted at two of the SEARCH study sites, included 80 participants aged 10–21 years with type 2 diabetes and 167 age-matched controls (Diabetes Care 2008;31:470–5).

Overall, the prevalence of breast-feeding for any length of time was significantly lower in youth with type 2 diabetes, compared with controls (31% vs. 64%).

Breast-feeding was also significantly associated with lower body mass index z scores in the controls and with lower (but not significantly lower) BMI z scores in the youth with type 2 diabetes. The average duration of breast-feeding was significantly longer in the controls.

When participants were divided into three ethnic groups, prevalence of breast-feeding was lower in black youth with type 2 diabetes than in controls (20% vs. 27%), but this difference was not statistically significant. The difference remained significant in Hispanics (50% vs. 84%) and in non-Hispanic whites (39% vs. 78%).

The researchers noted previous evidence that a lower prevalence of breast-feeding in blacks, compared with other ethnicities, might be a confounding variable, but they said that the overall presence of a protective effect of breast-feeding against type 2 diabetes suggests that all populations might benefit it.

Vitamin D Cuts Risk of Type 1 Diabetes

Children receiving vitamin D supplementation are significantly less likely to develop type 1 diabetes, according to an analysis of observational studies led by Dr. Christos Zipitis of St. Mary's Hospital for Women and Children, Manchester, England.

In four case-control studies of 6,684 subjects in several European countries, children who received vitamin D supplementation in early childhood had a significantly reduced risk of developing type 1 diabetes in later life, compared with those who received no supplementation (pooled odds ratio 0.71), said the researchers (Arch. Dis. Child. 2008 March 13 [Epub doi: 10.1136/adc.2007.128579]).

A cohort study also found significantly reduced risk for regular supplementation and irregular supplementation, when compared with no supplementation.

The authors found five studies that were relevant and fit their inclusion criteria, none of which was a randomized controlled trial. Because the case-control studies were retrospective and did not attempt to objectively confirm whether either cases or controls took vitamin D, nor how much of the vitamin they took, nor how much exposure to the sun they received, the findings could have been biased, they noted.

Lower Exercise Intensity in Obese Boys

Obese adolescent boys have a limited capacity to metabolize fat by exercising at the recommended moderate intensity level, and might do better with lower-intensity activity, according to Dr. Gautier Zunquin, a sports medicine researcher at the University of the Littoral Opal Coast, Dunkirk, France, and associates.

To date, no studies have compared the rate of fat oxidation during exercise in obese children with rates in lean children using the same protocol. Dr. Zunquin and associates did so because they suspected current exercise guidelines should be altered for obese adolescents (Br. J. Sports Med. 2008 April 1 [doi:10.1136/bjsm.2007.044529]).

They calculated the fat oxidation rate in 13 lean and 17 obese 12-year-old boys, which allowed them “to construct a curve of fat oxidation vs. exercise intensity for each individual.” The maximal fat oxidation rate occurred at a lower level of exercise in the obese boys than in the lean boys. The lean boys metabolized the most fat exercising at 50%–60% of peak oxygen consumption, whereas the obese boys metabolized the most fat exercising at 30%–50% of peak oxygen consumption.

“Muscular modifications induced by obesity and being sedentary may partially explain the differences in fuel oxidation mechanisms,” wrote the authors. Differences between the two groups in hormonal changes during exercise, fatty-acid mobilization, and activation of α₂-adrenergic receptors might also play a role.

“Exercise intensity should be adapted to [children's] metabolic capacities during weight management programs,” they said.

Breast-Feeding and Type 2 Diabetes

Breast-fed babies may be protected against developing type 2 diabetes during childhood regardless of ethnicity, according to results from a study adjunct to the ongoing SEARCH for Diabetes in Youth investigation, by Elizabeth J. Mayer-Davis, Ph.D., of the University of South Carolina, Columbia, and her colleagues.

Their case-control study, conducted at two of the SEARCH study sites, included 80 participants aged 10–21 years with type 2 diabetes and 167 age-matched controls (Diabetes Care 2008;31:470–5).

Overall, the prevalence of breast-feeding for any length of time was significantly lower in youth with type 2 diabetes, compared with controls (31% vs. 64%).

Breast-feeding was also significantly associated with lower body mass index z scores in the controls and with lower (but not significantly lower) BMI z scores in the youth with type 2 diabetes. The average duration of breast-feeding was significantly longer in the controls.

When participants were divided into three ethnic groups, prevalence of breast-feeding was lower in black youth with type 2 diabetes than in controls (20% vs. 27%), but this difference was not statistically significant. The difference remained significant in Hispanics (50% vs. 84%) and in non-Hispanic whites (39% vs. 78%).

The researchers noted previous evidence that a lower prevalence of breast-feeding in blacks, compared with other ethnicities, might be a confounding variable, but they said that the overall presence of a protective effect of breast-feeding against type 2 diabetes suggests that all populations might benefit it.

Vitamin D Cuts Risk of Type 1 Diabetes

Children receiving vitamin D supplementation are significantly less likely to develop type 1 diabetes, according to an analysis of observational studies led by Dr. Christos Zipitis of St. Mary's Hospital for Women and Children, Manchester, England.

In four case-control studies of 6,684 subjects in several European countries, children who received vitamin D supplementation in early childhood had a significantly reduced risk of developing type 1 diabetes in later life, compared with those who received no supplementation (pooled odds ratio 0.71), said the researchers (Arch. Dis. Child. 2008 March 13 [Epub doi: 10.1136/adc.2007.128579]).

A cohort study also found significantly reduced risk for regular supplementation and irregular supplementation, when compared with no supplementation.

The authors found five studies that were relevant and fit their inclusion criteria, none of which was a randomized controlled trial. Because the case-control studies were retrospective and did not attempt to objectively confirm whether either cases or controls took vitamin D, nor how much of the vitamin they took, nor how much exposure to the sun they received, the findings could have been biased, they noted.

Lower Exercise Intensity in Obese Boys

Obese adolescent boys have a limited capacity to metabolize fat by exercising at the recommended moderate intensity level, and might do better with lower-intensity activity, according to Dr. Gautier Zunquin, a sports medicine researcher at the University of the Littoral Opal Coast, Dunkirk, France, and associates.

To date, no studies have compared the rate of fat oxidation during exercise in obese children with rates in lean children using the same protocol. Dr. Zunquin and associates did so because they suspected current exercise guidelines should be altered for obese adolescents (Br. J. Sports Med. 2008 April 1 [doi:10.1136/bjsm.2007.044529]).

They calculated the fat oxidation rate in 13 lean and 17 obese 12-year-old boys, which allowed them “to construct a curve of fat oxidation vs. exercise intensity for each individual.” The maximal fat oxidation rate occurred at a lower level of exercise in the obese boys than in the lean boys. The lean boys metabolized the most fat exercising at 50%–60% of peak oxygen consumption, whereas the obese boys metabolized the most fat exercising at 30%–50% of peak oxygen consumption.

“Muscular modifications induced by obesity and being sedentary may partially explain the differences in fuel oxidation mechanisms,” wrote the authors. Differences between the two groups in hormonal changes during exercise, fatty-acid mobilization, and activation of α₂-adrenergic receptors might also play a role.

“Exercise intensity should be adapted to [children's] metabolic capacities during weight management programs,” they said.

Breast-Feeding and Type 2 Diabetes

Breast-fed babies may be protected against developing type 2 diabetes during childhood regardless of ethnicity, according to results from a study adjunct to the ongoing SEARCH for Diabetes in Youth investigation, by Elizabeth J. Mayer-Davis, Ph.D., of the University of South Carolina, Columbia, and her colleagues.

Their case-control study, conducted at two of the SEARCH study sites, included 80 participants aged 10–21 years with type 2 diabetes and 167 age-matched controls (Diabetes Care 2008;31:470–5).

Overall, the prevalence of breast-feeding for any length of time was significantly lower in youth with type 2 diabetes, compared with controls (31% vs. 64%).

Breast-feeding was also significantly associated with lower body mass index z scores in the controls and with lower (but not significantly lower) BMI z scores in the youth with type 2 diabetes. The average duration of breast-feeding was significantly longer in the controls.

When participants were divided into three ethnic groups, prevalence of breast-feeding was lower in black youth with type 2 diabetes than in controls (20% vs. 27%), but this difference was not statistically significant. The difference remained significant in Hispanics (50% vs. 84%) and in non-Hispanic whites (39% vs. 78%).

The researchers noted previous evidence that a lower prevalence of breast-feeding in blacks, compared with other ethnicities, might be a confounding variable, but they said that the overall presence of a protective effect of breast-feeding against type 2 diabetes suggests that all populations might benefit it.

Vitamin D Cuts Risk of Type 1 Diabetes

Children receiving vitamin D supplementation are significantly less likely to develop type 1 diabetes, according to an analysis of observational studies led by Dr. Christos Zipitis of St. Mary's Hospital for Women and Children, Manchester, England.

In four case-control studies of 6,684 subjects in several European countries, children who received vitamin D supplementation in early childhood had a significantly reduced risk of developing type 1 diabetes in later life, compared with those who received no supplementation (pooled odds ratio 0.71), said the researchers (Arch. Dis. Child. 2008 March 13 [Epub doi: 10.1136/adc.2007.128579]).

A cohort study also found significantly reduced risk for regular supplementation and irregular supplementation, when compared with no supplementation.

The authors found five studies that were relevant and fit their inclusion criteria, none of which was a randomized controlled trial. Because the case-control studies were retrospective and did not attempt to objectively confirm whether either cases or controls took vitamin D, nor how much of the vitamin they took, nor how much exposure to the sun they received, the findings could have been biased, they noted.