| Previous studies have demonstrated that endurance exercise training
increases the level of heat shock proteins (HSPs) in skeletal muscles.
However, little attention has been drawn to the effects of high intensity-short
duration exercise, or sprint- interval training (SIT) on HSP72 level
in rat skeletal muscles. This study performed to test the hypothesis
that the SIT would induce the HSP72 in fast and slow skeletal muscles
of rats. Young male Wistar rats (8 weeks old) were randomly assigned
to a control (CON) or a SIT group (n = 8/group). Animals in the SIT
group were trained (1 min/sprint, 6~10 sets/day and 5~6 days/week)
on a treadmill for 9 weeks. After the training period, HSP72 levels
in the plantaris (fast) and soleus (slow) muscles were analyzed by
Western blotting method. Enzyme activities (hexokinase, phosphofructokinase
and citrate synthase) and histochemical properties (muscle fiber type
compositions and cross sectional area) in both muscles were also determined.
The SIT resulted in significantly (p < 0.05) higher levels of HSP72
in both the plantaris and soleus muscles compared to the CON group,
with the plantaris producing a greater HSP72 increase than the soleus
(plantaris; 550 ± 116%, soleus; 26 ± 8%, p < 0.05).
Further, there were bioenergetic improvements, fast-to-slow shift
of muscle fiber composition and hypertrophy in the type IIA fiber
only in the plantaris muscle. These findings indicate that the SIT
program increases HSP72 level of the rat hindlimb muscles, and the
SIT-induced accumulation of HSP72 differs between fast and slow muscles.
KEY
WORDS: Hindlimb, treadmill running, enzyme activity, fiber type
shift, hypertrophy.
|
