DISCUSSION
We investigated the effects of a 10-minute massage performed
3 hours after an eccentric exercise on DOMS and other
indicators of eccentric-exercise–induced muscle damage. We
used a self-report visual analog scale to quantify the magnitude
of muscle soreness for palpation , extension, and flexion of the
elbow flexors ; this scale has been reported to be the most
satisfactory means of assessing pain sensation. 19 Because the
perception of pain is highly subjective and varies widely
among individuals, the use of soreness as a quantifier of muscle
injury is problematic. 5 Yet it is the most widely experienced
negative consequence of eccentric exercise, making it
an important variable to consider. To minimize the confounding
effects associated with difference in individual responses,
we used the arm-to-arm comparison model to compare massage
and control conditions.
The arm-to-arm comparison model is advantageous when
comparing 2 conditions in a relatively small number of subjects;
however, it may produce a carryover effect, especially
for the blood markers of muscle damage, if the time between
the bouts is short. We avoided this potential problem by providing
an adequate interval between the bouts based on previous
studies, which was more than 2 weeks. 2,18 Yet a possible
placebo effect should also be considered, because it is difficult
to eliminate a possible placebo effect in the arm-to-arm comparison
model. Practically, people expect to have some effects
of massage when they receive it, and psychological effects
may always exist to some degree. We did not include a placebo
treatment such as touching, because subjects might have noticed
a difference if they had received a placebo treatment for
one arm and actual treatment for the other arm. However, subjects
were randomly grouped by test order (control-treatment
or treatment-control), and dominant and non dominant arms
were equally balanced over the 2 conditions. Moreover, the
changes in muscle strength (see Table 1 and Figure 1), ROM,
and upper arm circumference (see Table 2) immediately post
exercise were not significantly different between the control
and massage arms, and the massage was performed 3 hours
post exercise and before DOMS developed. It seems unlikely
that the changes in the criterion measures were altered by the
psychological effects of massage, because the placebo effect
would not account for the differences in upper arm circumference
or CK values. This suggests that the reduction in
DOMS for the massage condition was a real and not a placebo
response. It seems reasonable to assume that differences between
arms, if any, were due to the effects of massage. Massage
was effective in reducing the magnitude of DOMS (see
Table 3), swelling (see Table 2), and plasma CK activity (see
Figure 2). In contrast, no positive effects of massage were
found for muscle strength (see Figure 1 and Table 1) and ROM
(see Table 2).