© Springer-Verlag 2001
Barry M. Prior1,
,
Roop C. Jayaraman3, Robert W. Reid2, Thomas G. Cooper4,
Jeanne M. Foley2, 3, Gary A. Dudley5 and Ronald A. Meyer2,
4
| (1) | University of Missouri-Columbia, Department of Veterinary Biomedical Sciences, E102 Vet Med Bld., 1600 Rollins Road, Columbia, MO 65211, USA |
| (2) | Department of Physiology, Michigan State University, East Lansing, MI 48824, USA |
| (3) | Department of Kinesiology, Michigan State University, East Lansing, MI 48824, USA |
| (4) | Department of Radiology, Michigan State University, East Lansing, MI 48824, USA |
| (5) | Department of Exercise Science, University of Georgia, Athens, GA 30602, USA |
Abstract. We hypothesized that activation of the quadriceps femoris
muscle group during eccentric exercise is related to the increase in magnitude
of several markers of muscle injury that developed during the next week.
Fourteen male subjects performed six to eight sets of five to ten repetitions of
single-leg eccentric-only seated knee extension exercise. Magnetic resonance (MR)
images were collected before and immediately after exercise and on days 2-4
and 6 after eccentric exercise. Changes in maximal voluntary contraction (MVC),
perceived soreness, muscle volume and muscle transverse relaxation of water
protons (T2) were determined for the quadriceps femoris muscle group
each day. Changes in muscle volume and T2 were determined every day
for each muscle [vastus lateralis (VL), vastus medialis (VM), vastus intermedius
(VI), rectus femoris (RF)] of the quadriceps femoris group. Post-exercise T2
was greater than pre-exercise T2 (P<0.05) for all muscles.
The acute 
T2
(Post-Pre) was similar (P>0.05) among VL, VM, VI, and RF [5.5 (0.3) ms],
suggesting that the four muscles were equally activated during eccentric
exercise. In the week after eccentric exercise, subjects experienced
delayed-onset muscle soreness (DOMS) and all muscles demonstrated a delayed
increase in T2 above pre-exercise values (P<0.05),
suggesting that muscle injury had occurred. For the quadriceps femoris muscle
group, there was no correlation between acute T2
and delayed (peak T2 during days 2, 3, 4, 6 minus pre-exercise T2)
T2 (r=0.04,
P>0.05). Similar results were obtained when VL, VM, VI and RF were
examined separately. Of the four muscles in quadriceps femoris, the biarticular
RF experienced greater muscle injury [delayed T2=15.2
(2.0) ms] compared to the three monoarticular vasti muscles [delayed T2=7.7
(1.3) ms; P<0.05]. We propose that the disproportionate muscle
injury to RF resulted from an ineffective transfer of torque from the knee to
hip joint during seated eccentric knee extension exercise, thus causing RF to
dissipate greater energy than normal. We conclude that in humans, muscle
activation is not a unique determinant of muscle injury.
Keywords. Delayed-onset muscle soreness (DOMS) - Eccentric exercise - MRI - Quadriceps femoris - Transverse relaxation