Exercise as it relates to Disease/High volume‐low intensity exercise camp and glycemic control in diabetic children

This Paper is a review of the article 'High volume‐low intensity exercise camp and glycemic control in diabetic children' (Ruzic et. al, 2007).

Background research

This paper looked at the effects of high volumes of low intensity programmed exercise on the improvement of glycemic control in children diagnosed with diabetes mellitus (type 1). Glycemic control is characterised as maintaining euglycemic (normal) blood glucose levels, which in a diabetic child ranges from 4-9 mol/L depending on exercise and time of day.

While it is well understood that exercise is an extremely effective tool to help control blood glucose and other glycemic characteristics, there are still significant numbers of diabetic children who do not engage in sufficient amounts of physical activity. With much literature suggesting that exercise in diabetic patients comes with increased risks of hypoglycemia and hyperglycemia; particularly the former, it is understandable that children and their carers may be hesitant to engage in exercise and organised physical activities.

Summer camps have become an increasing popular exercise intervention with this particular population. With their increasing popularity there have been several studies based out of these camps investigating exercise and its effect on diabetes. Most of these studies do not achieve exercise volumes as large as this study investigates.

Where is this research from?

This study was published in the journal of paediatrics and Child health, coming from the Faculty of Kinesiology at the University of Zagreb, Zagreb Croatia. It was completed in partnership with the Croatia Association for Diabetic Societies and the Paediatric branch of the University of Zagreb Hospital (also known as Sisters of Charity). It's Authors Dr Lana Ruzic, Professor Goran Sporis and Branka Matkovic have an immense amount of experience in the sport and exercise science industry, as well as significant publishing experience.

What kind of research was this?

This study was an intervention based observational study. This means, the same group of participants were monitored before and after the particular intervention, and their initial and final results compared. In this study 185 participants were invited the camp based upon selection criteria. 28 participants were then selected, only 20 were used for the data analysis. Participants were already members of the Croatian Association for Diabetic Societies and had been treated at the Vuk Vrhovac clinic.

What did the research involve?

Summary of study procedures:

For this particular study 28 participants aged 9 –16, participated in a summer camp on an island in Croatia for 15 days. On each day of the camp the participants completed approximately 4 hours of exercise, based on a strict schedule. The exercises varied in intensity and type, all exercise was prescribed by an exercise physiologist in conjunction with a kinesiologist. Exercise and the intensity are as follows:

Time of Day	Duration (hours)	Intensity (% of HRmax)
Morning (9:00)	1	50-60
Afternoon (16:00-18:00)	2	60-80
Evening (21:00)	1	55-75

Throughout the camp the children participated in a range of activities. These activities were set on a five-day cycle and repeated three times.

Time of Day	Activities Types (varied each day)
Morning (9:00)	Stretching, gymnastics, pilates, low intensity aerobics.
Afternoon (16:00 - 18:00)	Swimming (30 minutes across every afternoon session), Volleyball, handball, soccer, basketball, surfing/water activities, racquet sports.
Evening (21:00)	Walking, Nordic Walking, cycling, skating.

Throughout the exercise, heart rate blood glucose were Monitored. Blood glucose was also recorded at varying times of the day. Calorie intake was also predetermined and set for each individual and adjusted if needed. At the conclusion of the camp each participant received a recommended exercise program, to continue on with.

The study took measurements of the participants HbA1c, on the first day of before the camp, 10 days after the camp and two months after the camp.

Methodology review:

Strengths:

The summer camp setting allowed for a lot of biases and variables to either be eliminated or controlled, for example insulin dosage and calorie intake. The structure of the program was also designed off heart-rate models making physical exertion, and energy expenditure slightly more normalised. The exercises in the program were also very consistent, however contained enough variability to ensure proper adherence.

Potential improvements:

The final hour of exercise completed at the end of each day, was potentially completed too late at night. It has been well researched that exercise increases incidence of hypoglycemia and nocturnal hypoglycemia, exercising right before bed and without blood glucose checks throughout the night, there was the potential for participants to experience a severe nocturnal hypoglycaemic event.

The measurement of HbA1c, was an effective measurement, and given it is a historical measurement was measured at appropriate times. However for this particular study results were taken at 10 days after the camp, where they HbA1c reduction was very evident and then at 2 months when results had to basal levels. This gives us a general trend, however had more data been collected we may have a more accurate idea of how long the adaptions caused by the intervention lasted.

What were the basic results?

HbA1c Values	Mean	SD	p.
Initial	8.29	1.29	0.023
10 days after camp	7.92	1.42	0.029
2 months after camp	8.35	1.31	0.010

Note: significant p-value <0.05

Overall this type of intervention achieved the desired results. The number of children achieving a predetermined satisfactory HbA1c result (<7.5%) doubled (to 8) when measured 10 days after the camp, the average values for HbA1c also dropped significantly. The researchers also found a drop in blood glucose (when measured after meals) in many of the participants in the final days of the camp.

The researches of this paper deemed this intervention a short-term success. They found that the exercise prescription achieved the desired results, however these adaptions where not as long lasting as they hoped, with results reverting to baseline measures at around two months after the termination of exercise.

Conclusions

With low incidence of hypoglycemia (only two recorded cases) and significant improvements in glycemic control this study illustrates the effectiveness of high volume and low intensity exercise. With the final results measured after two months showing regression back to initial data this study also highlights the importance of continued and habitual exercise and exercise behaviours in the ongoing management of diabetes mellitus.

Recent research would suggest that whilst continual aerboic based low-moderate intensity exercise is an effective tool to improve glycemic control, introducing high-intensity bouts of exercise can help reduce the risk of hypoglycemia and particularly nocturnal hypoglycemia.

Practical implications

• This type of exercise was very effective in a controlled environment, however once the camp ended not one participant reported adherence to exercise recommendations for the end of the study.
• Organised participation will receive the best adherence (particularly in children) and help build habitual exercise behaviours.
• Ongoing organised programs e.g. built into school curriculums or through clubs with the support of parents will be the best chance of using this type of intervention in the long term.

Further readings

Below are some addition resources:

• American Diabetes Association
• Diabetes Australia
• Pediatric Diabetes
• World Health Organisation (WHO)