Free IGF-I(DSL ELISA) decreased by 50
± 5 % during the race and remained decreased at POST 24 h. Free IGF-I was 0.4 (0.1-1.0) % of total IGF-I at PRE and did not change significantly.
Pediatric Endocrinology Unit Q2:08 e-mail: Ulrika.Berg@.ki.se In cooperation with: Dept of Physiology and Pharmacology, Karolinska Institutet, (Stockholm) Dept of Woman and Child Health Karolinska Institutet Åstrand Lab of Work Physiology, Swedish School of Health Sciences, Stockholm Astrid Lindgren Children´s Hospital 171 77 Stockholm, SWEDEN.
The IGF-IGFBP system during ultra-endurance
exercise in men and women
free IGF-I
time point
PRE END POST 24h
se ru m fr ee IG F -I (µ g/ L) 0,5 1 1,5 ***** * "EXERCISE" total IGF-I time point PRE END POST 24h
se ru m to ta l I G F -I ( µg /L ) 0 100 200 300 400 500 ***** ***** "EXERCISE" "EXERCISE"
IGFBP-3 protease activity
time point
PRE END POST 24h
S er um IG F B P -3 P A ( % ) 50 52 54 56 58 60 * # Women Men
SUMMARY AND CONCLUSION
Under extreme exercise conditions increased IGFBP-3 proteolysis
can not fully compensate the effects of decreased t-IGF-I and
increased IGFBP-1 on circulating IGF-I bioavailability.
INTRODUCTION
Ultra-endurance exercise
during 6 days is related to
negative energy balance.
The effects on the
circulatory components of
the IGF-IGFBP system were
investigated.
RESULTS
Median energy expenditure
(method modified from Weir et
al 1949
) was 77047 (range
64235-113845) kcal during the
race (n = 6). Body weight
decreased by 1 ± 1 %. Energy
intake was registered in 3 men
and covered 75, 85 and 87 %
of the energy expenditure
during the race.
DESIGN
Subjects:
10 men and 8 women
(32 ± 1 years, BMI 24 [20-26] kg ·
m
-2performed ultra-endurance
exercise (mainly running, kayaking,
biking, climbing). Median duration of
the race was 6.3 (range 5.2 -7.3)
days. Blood samples were drawn
before (PRE; n=18), at the end of
(END; n =18) and 24 hours after
(POST24h; n=12) the race. Food
and drink intake was ad libitum.
IGFBP-1(DSL ELISA) increased by 127 ± 36 % during the race and had returned back to basal levels at POST 24h. At PRE, IGFBP-1 correlated negatively with f-IGF-I. No correlation was found at END or post 24h.
U. Berg, J. Enqvist, M. Mattson, C. Carlsson-Skwirut, Carl. J. Sundberg, B. Ekblom, P. Bang.
Total IGF-I(RIA) decreased by 44 (62-97) % during the race and remained decreased at POST 24h. The decrease in t-IGF-I was most marked in subjects with the largest energy deficit (n = 3 available).
Serum IGFBP-3 fragmentation(WLB) increased by 23 ± 4 % during exercise.
Serum IGFBP-3 protease activity(protease
assay) increased significantly only in women.
IGFBP-2 (WIB) increased by 29 ± 9 % during the race. In women, IGFBP-2 levels remained elevated at POST 24h.
Change in f-IGF-I at END (% from basal) -100 -80 -60 -40 -20 0 C ha ng e in IG F B P 3 fr ag m en ta tio n at E N D ( % fr om b as al ) -10 0 10 20 30 40 50 60
There was a correlation between the increase in serum IGFBP-3 fragmentation and the decrease in f-IGF-I during the race.
Foto: Peder Sundström
Total IGFBP-1
time point
PRE END POST 24h
se ru m to ta l I G F B P -1 ( µg /L ) 0 20 40 60 80 100 ** "EXERCISE" IGFBP-3 fragmentation time point
PRE END POST 24h
se ru m I G F B P -3 fr a gm en ta tio n (% ) 30 35 40 45 50 55 60 65 ** "EXE RCISE" R = -0.63 P = 0.005 "EXERCISE" * * IGFBP-2 time point
PRE END POST 24h
S er um I G F B P -2 ( A U ) 1 2 3 4 # * * "EXERCISE" MEN WOMEN * #
