Saturday, March 29, 2008

Research Update--Changes due to eccentric exercise?

Changes due to eccentric exercise?
Some more studies for you! We know that a great way to create a lot of Delayed Onset Muscle Soreness (DOMS) is by eccentric exercise. Again, I am not recommended that you go out of your way to create muscle damage, but it happens and is probably an important step in the hypertrophy (increase in muscle size) process. Now that does not mean that it is always painful, however. Pain is an interpretation in the brain! Below are some brand new studies to shed some light on what is really going on....

(NOTE--the hyperlinks below are all fixed now!)

Sensory and electromyographic mapping during delayed-onset muscle soreness

Authors: Hedayatpour,N.; Falla,D.; Arendt-Nielsen,L.; Farina,D.
Source: Med.Sci.Sports Exerc., 2008, 40, 2, 326-334

Conclusion: "Novel topographical mapping of both surface EMG (Electromyography) and PPT (Pressure-pain thresholds) of the quadriceps showed site-dependent effects of eccentric exercise, probably attributable to variations in the morphological and architectural characteristics of the muscle fibers. Greater manifestations of DOMS (Delayed Onset Muscle Soreness) in the distal region of the quadriceps may indicate a greater susceptibility of this region to further injury after eccentric exercise."

Effects of neuromuscular electrical stimulation of the knee extensor muscles on muscle soreness and different serum parameters in young male athletes: preliminary data

Authors: Zorn,C.; Szekeres,T.; Keilani,M.; Fialka-Moser,V.; Crevenna,R.
Source: Br.J.Sports Med., 2007, 41, 12, 914-916

Conclusions: "Although the changes of blood parameters measured in the present work correspond to those reported in the literature on eccentric strength training, no delayed onset muscle pain could be detected. Further studies should be carried out, also investigating different stimulation protocols in non-trained healthy subjects and in patients with less muscle mass."

Uniform and prolonged changes in blood oxidative stress after muscle-damaging exercise

Authors: Paschalis,V.; Nikolaidis,M.G.; Fatouros,I.G.; Giakas,G.; Koutedakis,Y.; Karatzaferi,C.; Kouretas,D.; Jamurtas,A.Z.
Source: In Vivo, 2007, 21, 5, 877-883

Conclusion: "We believe that muscle-damaging exercise should be viewed as a different challenge compared to non-muscle-damaging exercise with regard to its effects on blood oxidative stress."

Adaptive changes in motor control of rhythmic movement after maximal eccentric actions

Authors: Bottas,R.; Nicol,C.; Komi,P.V.; Linnamo,V.
Source: J.Electromyogr.Kinesiol.

Conclusion: "The present results emphasize the capacity of the neuromuscular system to compensate for prolonged eccentric-induced contractile failure by optimizing antagonistic muscles coordination in a demanding rhythmic task. The underlying compensatory mechanisms could be related to increased sensitization of small diameter muscle nerve endings."

Decreased blood oxidative stress after repeated muscle-damaging exercise

Authors: Nikolaidis,M.G.; Paschalis,V.; Giakas,G.; Fatouros,I.G.; Koutedakis,Y.; Kouretas,D.; Jamurtas,A.Z.
Source: Med.Sci.Sports Exerc., 2007, 39, 7, 1080-1089

Conclusion: "A repeated bout of lengthening contractions attenuated muscle damage and blood oxidative stress compared with the first bout."

Myofibre damage in human skeletal muscle: effects of electrical stimulation versus voluntary contraction

Authors: Crameri,R.M.; Aagaard,P.; Qvortrup,K.; Langberg,H.; Olesen,J.; Kjaer,M.
Source: J.Physiol., 2007, 583, Pt 1, 365-380

Conclusion: "The present study demonstrates that in human muscle, the delayed onset of muscle soreness was not significantly different between the two treatments despite marked differences in intramuscular histological markers, in particular myofibre proteins and satellite cell markers. An increase in tenascin C expression in the midbelly of the skeletal muscle in both legs provides further evidence of a potential role for the extra cellular matrix in the phenomenon of delayed onset of muscle soreness."

Changes in serum cytokines after repeated bouts of downhill running

Authors: Smith,L.L.; McKune,A.J.; Semple,S.J.; Sibanda,E.; Steel,H.; Anderson,R.
Source: Appl.Physiol.Nutr.Metab., 2007, 32, 2, 233-240

Conclusion: "The pro-inflammatory macrophage inflammatory factor-1beta (MIF-1beta) was 18% higher during the 12 h after RUN2. The overall cytokine profile suggests a slight reduction in systemic inflammation after RUN2."

Quantifying delayed-onset muscle soreness: a comparison of unidimensional and multidimensional instrumentation

Authors: Cleather,D.J.; Guthrie,S.R.
Source: J.Sports Sci., 2007, 25, 8, 845-850

Conclusion: "So the findings may be of use to researchers and sports medicine professionals in their deliberations about which instrumentation to use in quantifying DOMS (Delayed Onset Muscle Soreness) and in distinguishing such pain from other, potentially more serious, musculoskeletal damage."

Delayed onset muscle soreness does not alter O2 uptake kinetics during heavy-intensity cycling in humans

Authors: Schneider,D.A.; Berwick,J.P.; Sabapathy,S.; Minahan,C.L.
Source: Int.J.Sports Med., 2007, 28, 7, 550-556

Conclusion: "The change in blood lactate concentration from rest to end-exercise was significantly greater during exercise performed with DOMS (Delayed Onset Muscle Soreness). Eccentric exercise causing a moderate degree of DOMS (Delayed Onset Muscle Soreness) does not appear to impact upon the mechanisms mediating phase II or the slow component of O2 uptake kinetics."