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Exercise capacity with special reference to type 2 diabetes

Tornberg, Åsa LU (2010) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2010:72.
Abstract (Swedish)
Popular Abstract in Swedish

Fysisk inaktivitet och fetma är ett växande hälsoproblem i hela världen.



Tre olika grupper av individer med ett brett spektrum av glukostolerans ingick i avhandlingen. Arbetskapacitet har studerats i en grupp friska fysiskt inaktiva medelålders män med normal glukostolerans i studie I och II. Hos en grupp äldre män med normal glukostolerans (NGT), nedsatt glukostolerans (IGT) och med typ 2 diabetes (T2D) studerades påverkan av insulinkänsligheten på arbetskapaciteten (studie III). Arbetskapacitet och effekten av kombinerad grupp träning studerades i en grupp medelålders kvinnor med T2D i studie IV och V.



Arbetskapaciteten vid cykelarbete hos inaktiva friska... (More)
Popular Abstract in Swedish

Fysisk inaktivitet och fetma är ett växande hälsoproblem i hela världen.



Tre olika grupper av individer med ett brett spektrum av glukostolerans ingick i avhandlingen. Arbetskapacitet har studerats i en grupp friska fysiskt inaktiva medelålders män med normal glukostolerans i studie I och II. Hos en grupp äldre män med normal glukostolerans (NGT), nedsatt glukostolerans (IGT) och med typ 2 diabetes (T2D) studerades påverkan av insulinkänsligheten på arbetskapaciteten (studie III). Arbetskapacitet och effekten av kombinerad grupp träning studerades i en grupp medelålders kvinnor med T2D i studie IV och V.



Arbetskapaciteten vid cykelarbete hos inaktiva friska män påverkades av nedre extremitetens muskelstyrka och muskulära uthållighet (Studie I), även överkroppens muskelstyrka relaterade till arbetskapacitet mätt på en ergometercykel. När överkroppens muskelstyrka ökade som svar på kombinerad gruppträning, ökade sambandet mellan muskelstyrka i överkroppen och arbetskapacitet (Studie II). Arbetskapacitet vid cykling påverkas av hel kropps insulinkänslighet och midja-höft kvoten (Studie III). Även muskelfibersammansättning (Studie I och III) och kapillär densitet (Studie III) bidrog till den maximala arbetskapaciteten. Uppskattning av VO2peak enligt Åstrand submaximal cykel test överskattar direkt mätt VO2peak hos kvinnor med T2D (studie IV). Ökad insulinkänslighet föreföll vara relaterad till träningens intensitet snarare än varaktighet, medan sänkning av HbA1c föreföll vara relaterad till träningsvolym hos kvinnor med T2D (Studie V).



Även om VO2peak och WRpeak är nära relaterade, kan det finnas olika förklaringsmekanismer. Muskelstyrka och muskulär uthållighet, inte bara benen utan även i armar och bål, kan vara viktiga aspekter vid ett maximalt cykeltest hos friska inaktiva män. Arbetskapaciteten var beroende av insulinkänslighet, muskelfibersammansättning och midja-höft kvoten hos individer med NGT, IGT och T2D som är matchade för ålder och BMI. Detta tyder på att metabolastörningar i skelettmuskel är av avgörande betydelse för arbetskapaciteten i en grupp med ett brett spektrum av insulinkänslighet. Submaximala tester för att skatta VO2peak bör användas med försiktighet hos patienter med T2D. Förbättrad insulinkänslighet efter sex månaders kombinerad gruppträning hos kvinnliga diabetiker var kopplat till träningsintensitet, medan minskningen av HbA1c är främst relaterad till träningsvolym. Metabola effekter av träning kan ses i avsaknad av en ökad arbetskapacitet. (Less)
Abstract
Physical inactivity and obesity is a growing health problem world wide.



Three different samples with a wide range of glucose tolerance were included in the thesis to represent a wider population. The exercise capacity was studied in one group of healthy sedentary middle aged men with normal glucose tolerance in study I and II. In a group of elderly men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and with type 2 diabetes (T2D) was the influence of insulin sensitivity on exercise capacity studied (Study III). Exercise testing and exercise training in individuals with T2D was examined in a group of middle aged women with T2D in study IV and V.



The performance of a maximal... (More)
Physical inactivity and obesity is a growing health problem world wide.



Three different samples with a wide range of glucose tolerance were included in the thesis to represent a wider population. The exercise capacity was studied in one group of healthy sedentary middle aged men with normal glucose tolerance in study I and II. In a group of elderly men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and with type 2 diabetes (T2D) was the influence of insulin sensitivity on exercise capacity studied (Study III). Exercise testing and exercise training in individuals with T2D was examined in a group of middle aged women with T2D in study IV and V.



The performance of a maximal incremental cycle test in sedentary healthy male subjects was highly affected by lower extremity muscular strength and muscular endurance (Study I). Also upper body muscular strength correlated to exercise capacity as measured by cycle ergometry. When exercise capacity and muscular strength of the upper body increased in response to combined supervised group training, the correlation between muscular strength of the upper body and exercise capacity improved (Study II). Exercise capacity assessed during cycling was affect by whole body insulin sensitivity and the waist-hip ratio (Study III). Also, fibre type composition (Study I and III) and capillary density (Study III) contributed to peak exercise capacity. Estimation of VO2peak according to Åstrand sub-maximal exercise testing significantly overestimates directly measured VO2peak in women with T2D (Study IV). Improved insulin sensitivity appeared to be related to exercise intensity rather than duration, whereas improved HbA1c appeared to be related to exercise volume in T2D women (Study V).



Though closely related, there may be different indices explaining VO2peak and WRpeak. Muscular strength and muscular endurance of not only the legs but also the arms and trunk may be important aspects of peak exercise capacity during a cycle test in healthy sedentary men. Exercise capacity is independently related to insulin sensitivity, muscle fibre composition and waist/hip ratio in subjects with NGT, IGT and T2D whom are matched for age and BMI. This suggests that metabolic abnormalities in skeletal muscle are of prime importance for the reduction in exercise capacity in over a wide range of insulin sensitivity. Sub-maximal tests should be used with caution in patients with T2D. Improvement in insulin sensitivity after six months combined supervised group training in female diabetic subjects is related to exercise intensity, whereas the reduction in HbA1c is related mainly to training volume. Metabolic effects of training may be seen in the absence of improved exercise capacity. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Wulff Helge, Jörn, Afd. for Systembiologisk forskning, Panum Instituttet, Köpenhamn
organization
publishing date
type
Thesis
publication status
published
subject
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2010:72
pages
154 pages
publisher
Lund University, Faculty of Medicine
defense location
Konferensrum 2007, Ingång 44, plan 2, Skånes Univeristetssjukhus Malmö
defense date
2010-06-14 09:15
ISSN
1652-8220
ISBN
978-91-86443-88-7
language
English
LU publication?
yes
id
a4fe2e98-8faa-4bfd-8b31-dccdeb533b21 (old id 1604037)
date added to LUP
2010-05-17 10:52:42
date last changed
2018-05-29 12:09:01
@phdthesis{a4fe2e98-8faa-4bfd-8b31-dccdeb533b21,
  abstract     = {Physical inactivity and obesity is a growing health problem world wide.<br/><br>
<br/><br>
Three different samples with a wide range of glucose tolerance were included in the thesis to represent a wider population. The exercise capacity was studied in one group of healthy sedentary middle aged men with normal glucose tolerance in study I and II. In a group of elderly men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and with type 2 diabetes (T2D) was the influence of insulin sensitivity on exercise capacity studied (Study III). Exercise testing and exercise training in individuals with T2D was examined in a group of middle aged women with T2D in study IV and V.<br/><br>
<br/><br>
The performance of a maximal incremental cycle test in sedentary healthy male subjects was highly affected by lower extremity muscular strength and muscular endurance (Study I). Also upper body muscular strength correlated to exercise capacity as measured by cycle ergometry. When exercise capacity and muscular strength of the upper body increased in response to combined supervised group training, the correlation between muscular strength of the upper body and exercise capacity improved (Study II). Exercise capacity assessed during cycling was affect by whole body insulin sensitivity and the waist-hip ratio (Study III). Also, fibre type composition (Study I and III) and capillary density (Study III) contributed to peak exercise capacity. Estimation of VO2peak according to Åstrand sub-maximal exercise testing significantly overestimates directly measured VO2peak in women with T2D (Study IV). Improved insulin sensitivity appeared to be related to exercise intensity rather than duration, whereas improved HbA1c appeared to be related to exercise volume in T2D women (Study V). <br/><br>
<br/><br>
Though closely related, there may be different indices explaining VO2peak and WRpeak. Muscular strength and muscular endurance of not only the legs but also the arms and trunk may be important aspects of peak exercise capacity during a cycle test in healthy sedentary men. Exercise capacity is independently related to insulin sensitivity, muscle fibre composition and waist/hip ratio in subjects with NGT, IGT and T2D whom are matched for age and BMI. This suggests that metabolic abnormalities in skeletal muscle are of prime importance for the reduction in exercise capacity in over a wide range of insulin sensitivity. Sub-maximal tests should be used with caution in patients with T2D. Improvement in insulin sensitivity after six months combined supervised group training in female diabetic subjects is related to exercise intensity, whereas the reduction in HbA1c is related mainly to training volume. Metabolic effects of training may be seen in the absence of improved exercise capacity.},
  author       = {Tornberg, Åsa},
  isbn         = {978-91-86443-88-7},
  issn         = {1652-8220},
  language     = {eng},
  pages        = {154},
  publisher    = {Lund University, Faculty of Medicine},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Exercise capacity with special reference to type 2 diabetes},
  volume       = {2010:72},
  year         = {2010},
}