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Intermittent High-Intensity Exercise Does Not Increase the Risk of Early Postexercise Hypoglycemia in Individuals With Type 1 Diabetes

¹ School of Human Movement and Exercise Science, University of Western Australia, Crawley, Western Australia, Australia
² Department of Endocrinology and Diabetes, Princess Margaret Hospital, Subiaco, Western Australia, Australia
³ Centre for Child Health Research, Telethon Institute of Child Health Research, University of Western Australia, Perth, Australia

Address correspondence and reprint requests to Kym J. Guelfi, BSc (Hons), School of Human Movement and Exercise Science, University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009, Australia. E-mail: kguelfi{at}cyllene.uwa.edu.au

Abbreviations: CON, control rest • IHE, intermittent high-intensity exercise

	INTRODUCTION

TOP INTRODUCTION RESEARCH DESIGN AND METHODS RESULTS CONCLUSIONS References

 
Exercise is generally recommended for individuals with type 1 diabetes because it is associated with numerous physiological (1,2) and psychological (3,4) benefits. However, participation in exercise can also increase the risk of experiencing severe hypoglycemia, during both exercise (5) and recovery (6). Unfortunately, there are no evidence-based guidelines for safe participation in intermittent high-intensity exercise (IHE), which characterizes most team and field sports, manual labor occupations, and spontaneous play in children. This is because the response of blood glucose levels to this type of exercise is not known, as previous research on intermittent exercise has employed exercise protocols that do not accurately reflect the high-intensity work–to–recovery ratios observed in intermittent sports (7,8). Therefore, the aim of this study was to investigate the effect of IHE that simulates the high-intensity work–to–recovery ratios observed in intermittent sports on blood glucose levels and glucoregulatory hormones in individuals with type 1 diabetes in order to assess the risk of hypoglycemia.

	RESEARCH DESIGN AND METHODS

TOP INTRODUCTION RESEARCH DESIGN AND METHODS RESULTS CONCLUSIONS References

 
Eight volunteers with type 1 diabetes (aged [±SD] 18.6 ± 2.1 years, BMI 22.1 ± 1.5 kg/m², VO_2peak 42.4 ± 7.3 ml · kg^–1 · min^–1, type 1 diabetes duration 7.0 ± 4.6 years, and HbA_1c 7.0 ± 0.4%), who were free of complications and not taking any prescribed medication other than insulin, gave informed consent to participate in the study in accordance with both the University of Western Australia and Princess Margaret Hospital Human Ethics Committees.

The participants visited the laboratory on three separate occasions, first for a familiarization session followed by either a control rest (CON) or IHE trial administered in a random counterbalanced order. At 8:00 AM on CON and IHE trials, the participants injected their usual morning insulin into the abdomen (mean dose 9.4 ± 4.8 units), or in the case of one participant on subcutaneous insulin infusion pump, their usual insulin bolus was infused. Following this, all participants consumed their normal breakfast, which was standardized to be identical on both visits. An antecubital vein was subsequently cannulated for blood sampling, while capillary blood was sampled from a hyperemic earlobe every 15 min for determination of blood glucose levels, which peaked postprandially and then began to decline. As blood glucose levels approached 11 mmol/l, either the CON or IHE protocol was commenced (112 ± 27 min after insulin injection). This procedure was designed to simulate a "real life" situation in which insulin is injected and food is consumed before morning exercise. The IHE protocol was based on time-motion analyses of various intermittent sports (9–11) and spontaneous play in children (12) and consisted of 11 4-s maximal sprints repeated every 2 min on a cycle ergometer for a total duration of 20 min. In contrast, the CON protocol required the participants to be seated on the cycle ergometer for 20 min without exercise. Capillary blood from the hyperemic earlobe and venous blood from the cannulated antecubital vein were sampled during both protocols and for the first hour of recovery. Data were analyzed using two-way repeated-measures ANOVA and paired samples t tests using the SPSS 11.0 for Windows software package. Statistical significance was accepted at P < 0.05. Data are expressed as means ± SD.

	RESULTS

TOP INTRODUCTION RESEARCH DESIGN AND METHODS RESULTS CONCLUSIONS References

 
All trials were commenced when plasma insulin levels were high following subcutaneous injection (178.6 ± 60.7 vs. 198.1 ± 148.0 pmol/l, CON vs. IHE), and there was no difference in insulin levels between trials. Mean blood glucose levels before the commencement of exercise was 10.9 ± 1.9 mmol/l in CON and 11.0 ± 1.8 mmol/l in IHE, and blood glucose level results were normalized relative to these starting levels (Fig. 1A). During the first 15 min of IHE, blood glucose levels declined more rapidly compared with CON (P < 0.05), indicating that the risk of hypoglycemia was increased at this time. However, during the subsequent hour of recovery from IHE, blood glucose levels remained stable, while continuing to decline in CON (P < 0.05), suggesting that the risk of hypoglycemia was not increased during early recovery from IHE.

View larger version (33K): [in this window] [in a new window]   Figure 1— Effect of 20 min (represented by box) of IHE (•) or CON () on normalized blood glucose levels (A), epinephrine (B), norepinephrine (C), and growth hormone (D). Results are expressed as means ± SE. *Indicates statistically significant difference (P < 0.05) between IHE and CON.

	CONCLUSIONS

TOP INTRODUCTION RESEARCH DESIGN AND METHODS RESULTS CONCLUSIONS References

 
This study shows for the first time that IHE does not increase the risk of early postexercise hypoglycemia in individuals with type 1 diabetes. This is surprising since the exercise was commenced when plasma insulin levels were high, a time when exercise is generally not recommended (5). Some of the metabolic and hormonal responses to IHE, specifically elevated catecholamine and growth hormone levels, might contribute to preventing the decline in blood glucose levels during early recovery, since these hormones stimulate increased hepatic glucose production (13,14) and inhibit insulin-mediated glucose uptake (15,16).

Caution should be taken against the generalization of these findings to all types of IHE. First, the recovery between high-intensity bouts was passive, while in the field, intense bursts are often interspersed by periods of lower intensity activity (9–11). In addition, the duration of exercise examined here was only representative of a portion of a game, with many intermittent sports lasting for up to 90 min. Thus, more research of this kind is required to further characterize the risk of hypoglycemia associated with IHE and to assist in the development of improved guidelines to allow individuals with type 1 diabetes to safely enjoy the benefits of regular physical activity.

	Acknowledgments

 
The authors acknowledge the technical assistance of Leanne Youngs and Bettye Lulham and the financial support of a National Health and Medical Research Council and Juvenile Diabetes Research Foundation Program Grant (to T.W.J. and P.A.F.).

	Footnotes

 
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

Received for publication October 14, 2004. Accepted for publication October 14, 2004.

	References

TOP INTRODUCTION RESEARCH DESIGN AND METHODS RESULTS CONCLUSIONS References

 

1. Campaigne BN, Landt KW, Mellies MJ, James FW, Glueck CJ, Sperling MA: The effects of physical training on blood lipid profiles in adolescents with insulin-dependent diabetes mellitus. Phys Sports Med 13:83–89, 1985
   
2. Laaksonen DE, Atalay M, Niskanen LK, Mustonen T, Sen CK, Lakka TA, Uusitupa MIJ: Aerobic exercise and the lipid profile in type 1 diabetic men: a randomized controlled trial. Med Sci Sports Exerc 32:1541–1548, 2000[Medline]
   
3. Norris R, Carroll D, Cochrane R: The effects of aerobic and anaerobic training on fitness, blood pressure, and psychological stress and well-being. J Psychosom Res 34:367–375, 1990[Medline]
   
4. Wasserman DH, Zinman B: Exercise in individuals with IDDM. Diabetes Care 17:924–937, 1994[Medline]
   
5. Rabasa-Lhoret R, Bourque J, Ducros F, Chiasson J-L: Guidelines for premeal insulin dose reduction for postprandial exercise of different intensities and durations in type 1 diabetic subjects treated intensively with a basal-bolus insulin regimen (ultralente-lispro). Diabetes Care 24:625–630, 2001[Abstract/Free Full Text]
   
6. Tuominen JA, Karonen S-L, Melamies L, Bolli G, Koivisto VA: Exercise-induced hypoglycaemia in IDDM patients treated with a short-acting insulin analogue. Diabetologia 38:106–111, 1995[Medline]
   
7. Sills IN, Cerny FJ: Responses to continuous and intermittent exercise in healthy and insulin-dependent diabetic children. Med Sci Sports Exerc 15:450–454, 1983[Medline]
   
8. Ford T, Berg K, Latin R, Thomas L: The effect of exercise intensity on blood glucose in persons with type 1 diabetes. Int Sports J 3:91–100, 1999
   
9. Lothian F, Farrally M: A time-motion analysis of women’s hockey. J Hum Move Stud 26:255–265, 1994
   
10. Keane S, Reilly T, Hughes M: Analysis of work-rates in Gaelic football. Aust J Sci Med Sports 25:100–102, 1993
    
11. Withers RT, Maricic Z, Wasilewski S, Kelly L: Match analyses of Australian professional soccer players. J Hum Move Stud 8:159–176, 1982
    
12. Bailey RC, Olson J, Pepper SL, Porszasz J, Barstow TJ, Cooper DM: The level and tempo of children’s physical activities: an observational study. Med Sci Sports Exerc 27:1033–1041, 1995[Medline]
    
13. Purdon C, Brousson M, Nyveen SL, Miles PDG, Halter JB, Vranic M, Marliss EB: The roles of insulin and catecholamines in the glucoregulatory response during intense exercise and early recovery in insulin-dependent diabetic and control subjects. J Clin Endocrinol Metab 76:566–573, 1993[Abstract]
    
14. Press M, Tamborlane WV, Sherwin RS: Importance of raised growth hormone levels in mediating the metabolic derangements of diabetes. N Engl J Med 310:810–815, 1984[Abstract]
    
15. Marliss EB, Simantirakis E, Miles PDG, Purdon C, Gougeon R, Field CJ, Halter JB, Vranic M: Glucoregulatory and hormonal responses to repeated bouts of intense exercise in normal male subjects. J Appl Physiol 71:924–933, 1991[Abstract/Free Full Text]
    
16. Jessen N, Djurhuus CB, Jørgensen JO, Møller N, Lund S, Schmitz O: The insulin signaling cascade is not involved in GH-induced insulin resistance in human skeletal muscle (Abstract). Diabetes 53 (Suppl. 2):A348, 2004
    

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