european college of sport science

IS-BM03 Adaptation in tendons and connective tissues in response to loading
to elucidate the genetic factors relevant to variation in several phenotypes important for health and physical performance. It is an important
first step in selection of research tools for further elucidation of the genetic mechanisms underlying variation in relevant traits.
Methods. To investigate effect of endurance swimming training on morphological parameters and endurance capacity (as a time of
swimming to exhaustion) depending on genetic background, 11-14 week old male mice from six inbred strains (A/J, BALB/cByJ, DBA/2J,
C3H/HeJ, C57BL/6J, and PWD/PhJ) were studied. Littermates were allocated into sedentary and trained groups (n=92 each) balanced by
strain, age and body weight. Skeletal muscle, cardiac ventricular mass, femur length, and the endurance capacity were measured at the
end of the five-week progressive endurance swimming training programme.
Results. Significant variation among inbred strains was observed in all tested phenotypes.
In conclusion, we identified a mouse model, which can be successfully used to shed light on the genetic mechanisms underlying variation
in musculoskeletal and cardiac characteristics and adaptation to endurance training.
References
Bray MS, Hagberg JM, Pérusse L, Rankinen T, Roth SM, Wolfarth B, Bouchard C. The human gene map for performance and healthrelated
fitness phenotypes: the 2006-2007 update. Med Sci Sports Exerc. 2009;41(1):35-73.
PERCUTANEOUS ELECTRICAL MUSCLE STIMULATION ATTENUATES POSTPRANDIAL HYPERGLYCEMIA IN OBESE MEN
KIMURA, T., MATSUMOTO, K., KAMEDA, N., HAYASHI, T., TANAKA, S., MORITANI, T.
KYOTO UNIVERSITY
Introduction: The patients with type 2 diabetes are encouraged to exercise after a meal to attenuate postprandial hyperglycemia in order
to reduce the risk of myocardial infraction. However, we know that there are diabetic patients who have a difficulty in performing physical
exercise as a consequence of excessive obesity and/or orthopedic problems. Now, we tried to develop percutaneous electrical muscle
stimulation (EMS), as an alternative to voluntary exercise, to treat postprandial hyperglycemia.
Methods: Eleven middle-aged obese men [age 43.7 (10.9) years, body mass 81.5 (9.2) kg, body mass index 27.4 (2.7) kg/m2, mean (SD)]
served as subjects. Each subject participated in two experimental sessions, i.e., one was a 20-min EMS after a breakfast (EMS trial) and
the other was a complete rest after a breakfast (Control trial). In EMS trial, quadriceps, biceps femoris, and gluteus maximus muscles
were simultaneously stimulated at 4 Hz. In each experimental session, blood sample was taken before and 30, 60, 90, and 120 minute
after the meal. Respiratory gas exchange and blood lactate concentration were measured during EMS and complete rest after a meal in
EMS and Control trials, respectively.
Results: The elevation of blood glucose after the meal observed in Control trial was significantly attenuated in EMS trial (P < 0.05). In
addition, the postprandial increase of blood insulin was significantly lowered in EMS trial (P < 0.05). It was also found that respiratory
quotient and blood lactate concentration were significantly increased during EMS (P < 0.05).
Discussion: The novel finding of this study was that postprandial hyperglycemia was significantly attenuated by a 20-min EMS after a
meal. In addition, the elevation of respiratory quotient and the increase in blood lactate concentration during EMS suggest that the attenuation
of postprandial hyperglycemia was mainly attributed to the enhanced anaerobic glycolysis in contracting muscle and subsequent
elevation of glucose uptake.
17:15 - 18:45
Invited symposia
IS-BM03 Adaptation in tendons and connective tissues in response to loading
REGULATORY FACTORS IN CONNECTIVE TISSUE ADAPTATION TO EXERCISE
HEINEMEIER, K.M.
BISPEBJERG HOSPITAL
Tendon tissue and the extracellular matrix of skeletal muscle are collagen rich tissues that are important for muscle function. Mechanical
loading via exercise/training induces collagen synthesis in both tendon and muscle. This indicates an adaptive response in the connective
tissue of the muscle-tendon unit. However, the precise mechanisms that lead from physical loading to changes in collagen production
are yet unknown. Several in vitro studies on connective tissue cells indicate that stress-responsive growth factors, such as transforming
growth factor-b-1 (TGF-b-1), insulin like growth factor-I (IGF-I) and connective tissue growth factor (CTGF) could be involved in this process.
These growth factors are expressed in response to mechanical stimuli and at the same time they induce expression of collagen in
connective tissue cells.
In support of this hypothesis, short-term strength training in rats leads to increased levels of TGF-b-1 and IGF-I expression in a pattern
closely resembling the increase in collagen expression in both tendon and muscle tissue. CTGF on the other hand does not seem influenced
by mechanical loading of tendon but does respond to loading of skeletal muscle.
Especially IGF-I may be an important player in connective tissue growth/maintenance. Recent findings show that increased systemic
levels of growth hormone (GH) elevates IGF-I systemically (as expected), but also locally in tendon and muscle tissue. Simultaneously
collagen mRNA expression and synthesis is increased in good correlation with local IGF-I expression. This suggests involvement of the
GH-IGF-I axis in the regulation of collagen synthesis in connective tissue.
474 14 TH
ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE