Exercise as it relates to Disease/A former career as a male elite athlete - does it protect against type 2 diabetes later in life?

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This is a critique of the article ‘A former career as a male elite athlete- does it protect against type 2 diabetes later in life?' written by M. K. Laine et al. and published in Diabetologia in 2014[1]

What is the background to this research?[edit]

Type 2 diabetes is common among those who are overweight and physically inactive[1][2]. It has been found that an increase in physical activity (PA), whether it be leisurely, occupation related PA, or an active transport method of 30 minutes or longer, have shown to significantly decrease the risk of type 2 diabetes [2]. There was, however, little evidence on the effects of frequent, vigorous PA, such as that of an elite athlete in training, on the prevalence of type 2 diabetes later in life [1]. Understanding the role that PA plays in the onset of diabetes later in life is beneficial as it can help to identify factors that can be modified to prevent the onset of diabetes or other health conditions, which may lead to more chronic health problems later in life [3].

Where is the research from?[edit]

The group that the research was conducted on included 392 former athletes from Finland, who had competed in at least one international competition in endurance or power training based sports, or a sport which used a mixture of both. The control group included age and area matched controls [1]. The authors of this particular study have undertaken many others, looking at the effects of vigorous PA, specifically that of former athletes, on the effects of a range of health factors including but not limited to telomere length [4], branched-chain amino acid (BCAA) as a surrogate for disturbed lipid metabolism[5] and hypertension[6], all using similar participant criteria which included the age and area matched controls. Considering each study commented on was published in different journals, under different organisations, there should be no bias or conflict of interest regarded in this study.

What kind of research was this?[edit]

This particular paper completed a cohort study, looking at former athletes who had competed at an international competition[1]. Cohort studies are the second highest level of unfiltered information on the evidence hierarchy, topped by randomised controlled trials, with case controlled studies following[7]. This means that the study is original and unfiltered, in comparison to unoriginal or filtered, which reviews unfiltered information and validates the use of its methods for collecting unfiltered information. Filtered information can include systematic reviews, critically appraised topics and critically appraised articles[7]. Filtered information sits at the top of the evidence hierarchy as these types of articles review and critique unfiltered information[7]. Selecting the type of study to complete is dependent on the research question posed. The study design that is chosen should be the one that will obtain the best information to answer the question[8].

What did the research involve?[edit]

The participants in this study completed a questionnaire in 1985 with additional questionnaires sent to the same cohort in 1995 and 2001. The participants who completed at least one survey and were still alive at the time, were invited to participate in a clinical study in 2008. The questionnaire included self-reported levels of leisure time physical activity (LTPA) as well as other lifestyle questions. LTPA recorded included intensity, duration and frequency of exercise over the previous three-month period for each survey. Given the question being asked; 'does a career as an elite athlete protect against type 2 diabetes later in life?' it was significant to gain multiple responses from each participant. To follow a group of participants over a period of almost 25 years, it would be important to ensure there is not a huge amount of effort required to participate, especially given the age of some participants. The questionnaire would have been easy to administer with one completed every 10 years and would not have required frequent thought about completion or constant contact with participants. The collection of self-reported data however, is one of the limitations of the study as there are many factors to accuracy that some people may have over/underestimated such as intensity, duration, whether they included active transport or an active occupation in their overall physical activity levels[1].

What were the basic results?[edit]

The results of this cohort study showed that former athletes reported higher levels of LTPA than non-athletes, completing 31.4 metabolic equivalent of task (MET) hours/week, compared to 20.5 MET hours/week. This correlates to the prevalence of type 2 diabetes and impaired glucose tolerance being significantly lower in former athletes, with endurance athletes showing the lowest prevalence of type 2 diabetes and impaired glucose tolerance among the former athlete group. The study also found that the prevalence of type 2 diabetes decreased, with an increase of 1 MET hour/week of exercise. This emphasises that exercise intensity is more important than total number of hours of PA completed. It was also stated that former athletes maintained long term physical activity better than non-athletes.

What conclusions can we take from this research?[edit]

From this particular research it seems to be quite clear that while exercise guidelines for combatting chronic health problems in the long term are provided and studied, the exercise intensity during those recommended PA guidelines is more important than the total time spent exercising. The findings from this paper align well with the information reviewed in a meta-analysis completed by Liubaoerjijin et al.[9] in 2016 which reviewed 8 studies where exercise intensity ranged from short bouts of high-intensity interval training (HIIT) to continuous training exercise where higher intensity exercise resulted in lower blood glucose over the duration of the study compared to the lower intensity exercise.

Practical advice[edit]

  • Before undertaking any form of high intensity exercise, it is important to undertake an exercise pre-screening and get a referral to an appropriate allied health professional if necessary.
  • After being cleared to exercise, LTPA including aerobic exercise and resistance training plays a major role in the prevention of type 2 diabetes
  • Exercise intensity is favoured over duration[1][3][9].
  • If you are new to exercise or unsure how to gain the benefits of exercise safely, seek out an appropriate allied health professional, who will be able to provide safe exercises and environments

Further information/resources[edit]

References[edit]

  1. a b c d e f g Laine MK, Eriksson JG, Kujala UM, Wasenius NS, Kaprio J, Bäckmand HM, Peltonen M, Mertsalmi TH, Sarna S. A former career as a male elite athlete—does it protect against type 2 diabetes in later life?. Diabetologia. 2014 Feb 1;57(2):270-4.
  2. a b Hu G, Lindström J, Valle TT, Eriksson JG, Jousilahti P, Silventoinen K, Qiao Q, Tuomilehto J. Physical activity, body mass index, and risk of type 2 diabetes in patients with normal or impaired glucose regulation. Archives of internal medicine. 2004 Apr 26;164(8):892-6.
  3. a b Yerramalla MS, Fayosse A, Dugravot A, Tabak AG, Kivimäki M, Singh-Manoux A, Sabia S. Association of moderate and vigorous physical activity with incidence of type 2 diabetes and subsequent mortality: 27 year follow-up of the Whitehall II study. Diabetologia. 2020 Mar 1;63(3):537-48.
  4. Laine MK, Eriksson JG, Kujala UM, Raj R, Kaprio J, Bäckmand HM, Peltonen M, Sarna S. Effect of intensive exercise in early adult life on telomere length in later life in men. Journal of sports science & medicine. 2015 Jun;14(2):239.
  5. Kujala UM, Peltonen M, Laine MK, Kaprio J, Heinonen OJ, Sundvall J, Eriksson JG, Jula A, Sarna S, Kainulainen H. Branched-chain amino acid levels are related with surrogates of disturbed lipid metabolism among older men. Frontiers in medicine. 2016 Nov 25;3:57.
  6. Laine MK, Kujala UM, Eriksson JG, Wasenius NS, Kaprio J, Bäckmand HM, Peltonen M, Heinonen O, Jula A, Sarna S. Former male elite athletes and risk of hypertension in later life. Journal of Hypertension. 2015 Aug 1;33(8):1549-54.
  7. a b c University of Canberra. Evidence Based Practice in Health. [Internet]. Canberra: University of Canberra Library; [ updated 2020 Sep 9; citeed 2020 Sep 16] available from: https://canberra.libguides.com/c.php?g=599346&p=4149721
  8. NCBI. What types of studies are there?. [Internet]. USA: Rockville Pike, Bethesda MD; [updated 2016 Sep 8; cited 2020 Sep 16]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK390304/#:~:text=There%20are%20various%20types%20of,to%20a%20number%20of%20questions.
  9. a b Liubaoerjijin Y, Terada T, Fletcher K, Boulé NG. Effect of aerobic exercise intensity on glycemic control in type 2 diabetes: a meta-analysis of head-to-head randomized trials. Acta diabetologica. 2016 Oct 1;53(5):769-81.