M. Zendzianpiotrowska et J. Gorski, METABOLIC ADAPTATION TO DAILY EXERCISE OF MODERATE INTENSITY TO EXHAUSTION IN THE RAT, European journal of applied physiology and occupational physiology, 67(1), 1993, pp. 77-82
The rats were made to run daily to exhaustion, for 28 days at a speed
of 1,200 m . h -1 on a treadmill set at a gradient of + 10-degrees. Th
e training increased the time of running to exhaustion [184 (SD 49) an
d 308 (SD 28) min on the lst and 28th day, respectively; P < 0.001 ].
The body mass was reduced by training [257 (SD 21) g before and 221 (S
D 20) g after; P<0.001 whereas the food intake increased [9 (SD 1) g .
100 g-1 body mass before and 14 (SD 2) g after; P < 0.001]. The heart
mass was not affected by training. Training increased the resting gly
cogen concentration in muscles composed of different fibre types (sole
us, white and red vastus muscles) and in the liver, but had no effect
on its concentration in the heart and diaphragm. During exercise lasti
ng for 30 min glycogen mobilization in the red vastus and soleus muscl
es and the liver was more pronounced after than before training. A ''s
paring'' effect of training on the skeletal muscles and liver glycogen
was markedly apparent only after exericse to exhaustion. The trained
rats, contrary to the untrained, did not develop hypoglycaemia during
exercise to exhaustion. An increase in the plasma free fatty acid conc
entration during exercise after training was delayed and attenuated co
mpared to that before training. The 24-h excretion of urea after exerc
ise to exhaustion on the 28th day of training was higher than on the l
st day by 39% (P<0.001). It is concluded that metabolic adaptation to
training consisting of daily bouts of exercise to exhaustion differs i
n many aspects from that so far described for other endurance training
protocols.