Relations between muscle soreness and biochemical and functional outcomes of eccentric exercise.

Correlations between functional and biochemical outcomes of eccentric exercise and between these outcomes and "delayed-onset muscle soreness" (DOMS) were studied. Maximal isotonic force, extension and flexion angle of the elbow, creatine kinase activity, and myoglobin concentration in serum were measured in 27 male subjects during 5 days after 120 maximal eccentric contractions of the forearm flexors. Significant correlations were found between values at 1 to 96 h after exercise for force (r = 0.55 to 0.96), flexion (0.52 to 0.94), extension (0.41 to 0.95), and myoglobin (0.55 to 0.97) and at 24 to 96 h for creatine kinase (0.67 to 0.96) and DOMS (0.45 to 0.72). Clusters of significant correlations (0.32 to 0.91) were found among all functional and biochemical measures. DOMS, however, showed only few and lower correlations with the other parameters (0.34 to 0.63). These results can practically be interpreted as follows: 1) subjects need more time to recover completely when early deviations after eccentric exercise are large, 2) a large change in one measure is accompanied by large deviations in other measures, and 3) objective outcomes of eccentric exercise are more accurate parameters than a DOMS score for use in effect studies.

31P-MRS and simultaneous quantification of dynamic human quadriceps exercise in a whole body MR scanner.

An ergometer for dynamic quadriceps exercise in a magnetic resonance (MR) scanner is physiologically validated, and its technical aspects are presented. The reproducibility of heart rate (HR), O2 consumption (VO2), and power (P) during two graded exercises on the MR ergometer was good (n = 8). Graded exercises on the MR ergometer and on a cycle ergometer (n = 17) were similar with respect to the regression lines between 1) HR and VO2 and 2) HR and P; also peak P did not differ significantly (280 +/- 37 and 298 +/- 41 W, respectively). Peak HR (171 +/- 14 and 184 +/- 15 beats/min, respectively), peak VO2 (3.00 +/- 0.51 and 3.54 +/- 0.44 l/min, respectively), and the slope of the regression line between P and VO2 were lower for MR exercise (P < 0.01). During quadriceps exercise in an MR scanner (n = 12), peak P was 64-143 W for the right leg, with corresponding inorganic phosphate-to-phosphocreatine ratios of 0.85-7.2. It is concluded that continuous noninvasive assessment of energy metabolism with 31P-MR spectroscopy and quantification of power output can be performed simultaneously during dynamic quadriceps exercise, without major reduction of the spectral resolution or the signal-to-noise ratio, and that exercise on this MR ergometer currently is the best possible approximation of cycling exercise for MR purposes.

Warm-up, stretching and massage diminish harmful effects of eccentric exercise.

The effect of a combination of a warm-up, stretching exercises and massage on subjective scores for delayed onset muscle soreness (DOMS) and objective functional and biochemical measures was studied. Fifty people, randomly divided in a treatment and a control group, performed eccentric exercise with the forearm flexors for 30 min. The treatment group additionally performed a warm-up and underwent a stretching protocol before the eccentric exercise and massage afterwards. Functional and biochemical measures were obtained before, and 1, 24, 48, 72 and 96h after exercise. The median values at the five post-exercise time points differed significantly for DOMS measured when the arm was extended (p = 0.043). Significant main effects for treatment were found on the maximal force (p = 0.026), the flexion angle of the elbow (p = 0.014) and the creatine kinase activity in blood (p = 0.006). No time-by-treatment interactions were found. DOMS on pressure, extension angle and myoglobin concentration in blood did not differ between the groups. This combination of a warm-up, stretching and massage reduces some negative effects of eccentric exercise, but the results are inconsistent, since some parameters were significantly affected by the treatment whereas others were not, despite the expected efficacy of a combination of treatments. The objective measures did not yield more unequivocal results than the subjective DOMS scores.

Phosphate metabolism of prior eccentrically loaded vastus medialis muscle during exercise in humans.

The possible alteration of metabolism of the m. vastus medialis was investigated during exercise after eccentric loading. Twelve male subjects performed stepping exercise for 25-60 min. One week before and 24 h after stepping they performed concentric leg exercise at stepwise increasing intensity, while power output was measured. During this concentric exercise and recovery therefrom, phosphorous metabolites were also measured in the m. vastus medialis with magnetic resonance spectroscopy. Creatine kinase and myoglobin in blood were measured before and 72 h after stepping. T1 and T2 1H-relaxation times for water were calculated from magnetic resonance images collected 72 h after stepping, and used as measures for oedema. The subjects perceived substantial soreness from 24 to 72 h after stepping. The ratio of inorganic phosphate over phosphocreatine at rest increased from 0.12 +/- 0.02 (before) to 0.19 +/- 0.04 (24 h after stepping) (P < 0.05). Creatine kinase activity was slightly elevated 72 h after stepping (71 [49-812] U L-1 [median, range]; P < 0.05) compared with baseline values (58 [26-409] U L-1), whereas myoglobin concentration was not significantly elevated (15 [8-120] micrograms L-1 compared with 8 [8-41] micrograms L-1). In the eccentrically exercised muscles, T1 and T2 values were not or only slightly higher than in the concentrically exercised contralateral muscles. The relation between power and the ratio of inorganic phosphate over phosphocreatine during concentric exercise, and the recovery data for inorganic phosphate, phosphocreatine and pH did not alter after stepping. These data suggest that quadriceps metabolism during concentric exercise and recovery therefrom is not affected by prior eccentric overload, but it cannot be excluded that metabolism will alter during exercise after more strenuous prior eccentric overload.

Changes in phosphorus compounds and water content in skeletal muscle due to eccentric exercise.

The interrelationship of the time courses of soreness and oedema, and of force and phosphorus metabolites after eccentric exercise was studied. Eight male subjects performed 120 maximal eccentric contractions with their left forearm flexors. Soreness, maximal force, flexion and extension elbow angle, and creatine kinase and myoglobin efflux were followed for 96 h after exercise. For equal periods T1 and T2 relaxation times and muscle cross-sectional area were calculated from magnetic resonance images as indications of oedema, and inorganic phosphate (P(i)) and phosphocreatine (PCr) were measured with magnetic resonance spectroscopy. Soreness on extension increased at 1 h (P = 0.043), T1 and T2 (both P = 0.01) and soreness when the arm was pressed (P = 0.028) at 24 h, and muscle cross-sectional area increased at 48 h (P = 0.01) after exercise. Soreness on extension reached a maximum at 48 h, the other four parameters at 72 h. All parameters related to oedema, and soreness, showed an increasing pattern for the period after exercise as a whole, but the largest increase between two points of measurement occurred earlier for soreness than for oedema. Creatine kinase increased significantly from baseline from 24 h onwards (P = 0.017) and myoglobin from 1 h onwards (P = 0.012). The P(i):PCr ratio differed from baseline for the first time 24 h after exercise (P = 0.018), increased to 225%, and then remained on a plateau until 72 h. Maximal isotonic force decreased to 53% at 1 h (P = 0.012).(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary MR angiography with ultrasmall superparamagnetic iron oxide particles as a blood pool agent and a navigator echo for respiratory gating: pilot study.

In nine healthy adult volunteers, pulmonary magnetic resonance angiography was performed with the blood pool agent NC100150 injection combined with respiratory gating with a navigator echo. With increasing doses of the contrast agent, higher signal intensities and vessel branch order visualization were achieved. No motion artifacts were seen. The blood pool agent NC100150 injection in combination with respiratory navigator gating permitted acquisition of high-quality MR angiograms of the pulmonary vasculature during continuous breathing.