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Biomedical subjects

P N Sfakianos

Publications and source records attributed to P N Sfakianos.

5 recordsLinked to original sources
PubMed1989

Blood indices of muscle injury associated with eccentric muscle contractions.

Serum muscle enzyme activities of eight healthy men (22-32 years old) were measured before and 48 h after separate bouts of repetitive concentric, eccentric, and isometric contractions of the lower leg anterior compartments. Serum creatine kinase and glutamic oxaloacetic acid transaminase levels were both elevated 2 days after the eccentric exercise regimen, exclusively (36 and 17%, respectively). Lactic dehydrogenase levels were not affected by any of the protocols. Delayed muscle soreness was exclusively reported from the eccentrically exercised limb. We suggest that the high tensions developed during eccentric exercise cause mechanical damage, possibly including sarcolemmal degeneration. Subsequently, muscle enzymes are released to the blood. We conclude that postexercise serum levels of some muscle enzymes, at the time of maximal soreness, are qualitative markers of muscle damage.

Adult↗
PubMed1988

Residual muscular swelling after repetitive eccentric contractions.

This investigation illustrates the morphological changes that take place following eccentric exercise and correlates those changes with intramuscular pressure readings. Eight healthy male subjects were asked to exercise their right lower leg anterior compartment eccentrically and their left concentrically. Four hundred submaximal contractions were performed in each exercise regimen over a 20-min period against a load corresponding to 15% of the individual's maximal dorsiflexion torque. Tissue fluid pressures were measured by the slit catheter technique before, during, and after exercise and 48 h later. Needle biopsies of both anterior tibialis muscles were also taken 48 h after completion of the exercise regimens. Overall morphology of the specimens revealed a greater cross-sectional fiber area (both type 1 and type 2) in the eccentrically exercised muscle as compared with the concentrically exercised muscle. Scant evidence of inflammation (only 1 of 8 of the "eccentric" muscle samples) and no fiber necrosis was observed. Fiber type proportions were equal on both sides and type 1 fiber biased (70%). Extremely large type 2 fibers were found in 4 of 8 subjects from the eccentric specimens. This incidence correlated significantly with the length of the time to return to resting pressure after eccentric exercise (r = 0.93, p less than 0.001). The percentage of water content was significantly higher in the eccentrically exercised muscle. Based on these findings, we conclude that muscle fiber swelling is a predominant feature following eccentric exercise and is directly associated with delayed muscle soreness.

Adenosine Triphosphatases↗
PubMed1987

Increased transsynovial transport with continuous passive motion.

Thirteen freshly killed immature rabbits were used to study the effect of continuous passive motion (CPM) on regional nutritional pathways of the medial and lateral menisci and the transport of a solute from synovial fluid to the patellar tendon. A bolus of 35SO4 was injected into each knee joint cavity. The right knee underwent CPM for 1 h, whereas the left knee was immobilized (rest extremity). Both knees were then rapidly resected and immediately frozen. The medial and lateral menisci were removed and sectioned into anterior, middle, and posterior thirds for Group 1 animals; in Group 2 animals a portion of patellar tendon was harvested. Radioactivity as counts per minute per milligram of tissue was counted in a scintillation counter. The posterior portion of the lateral meniscus in the rest extremity had significantly higher uptake than the extremity that underwent CPM (p less than 0.001). In the extremity at rest, the posterior third of the lateral meniscus had a significantly higher uptake than that of the middle third (p = 0.04). In Group 2 rabbits, the patellar tendon of the knee undergoing CPM had significantly higher uptake as compared with the patellar tendon of the knee at rest (p = 0.02). These results indicate that diffusion from synovial fluid to meniscal cells is an important mechanism of transport for low-molecular-weight nutrients such as sulfate; CPM does not facilitate this mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Muscle soreness and intramuscular fluid pressure: comparison between eccentric and concentric load.

This study investigates the dynamic and resting intramuscular pressures associated with eccentric and concentric exercise of muscles in a low-compliance compartment. The left and righ leg anterior compartments of eight healthy males (ages 22-32 yr) were exercised by either concentric or eccentric contractions of the same load (400 submaximal contractions at constant rate, 20/min for 20 min at a load corresponding to 15% of individual maximal dorsiflexion torque). Tissue fluid pressures were measured with the slit-catheter technique before, during, and after the exercise. Average peak intramuscular pressure generated during eccentric exercise (236 mmHg) was significantly greater than during concentric exercise (157 mmHg, P less than 0.001). Peak isometric contraction pressure in the eccentrically exercised compartment was significantly higher both within 20 min postexercise and on the second postexercise day (P less than 0.001). Resting pressure 2 days postexercise was significantly higher on the eccentrically exercised side (10.5 mmHg) compared with the concentrically exercised (4.4 mmHg, P less than 0.05). The ability to sustain tension during postexercise isometric contractions was impaired on the "eccentric" side. Soreness was exclusively experienced in the eccentrically exercised muscles. We conclude that eccentric exercise causes significant intramuscular pressure elevation in the anterior compartment, not seen following concentric exercise, and that this may be one of the factors associated with development of delayed muscle soreness in a tight compartment.

Adult↗