European journal of applied physiology
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Eur. J. Appl. Physiol. · May 2000
Cytokines and cell adhesion molecules associated with high-intensity eccentric exercise.
Unaccustomed, eccentrically biased exercise induces trauma to muscle and/or connective tissue. Tissue damage activates an acute inflammatory response. Inflammation requires the effective interaction of different physiological and biological systems. ⋯ Results were analyzed using a repeated-measures analysis of variance (P = 0.05). Compared to baseline values, IL-1beta was reduced (P = 0.03) at 6, 24, and 96-144 h after exercise; IL-6 was elevated (P = 0.01) at 12, 24, and 72 h after exercise; IL-10 was elevated (P = 0.009) between 72 and 144 h after exercise; M-CSF was elevated (P = 0.005) at 12 and 48-144 h after exercise; and P-selectin was reduced (P = 0.01) between 24 and 144 h after exercise. It is concluded that when high-intensity eccentric exercise is compared to strenuous endurance exercise, post-exercise changes in cytokines do occur, but they are generally of a smaller magnitude, and occur at a later time period after the termination of exercise.
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Eur. J. Appl. Physiol. · Mar 2000
Clinical TrialTension regulation during lengthening and shortening actions of the human soleus muscle.
In the present study we investigated tension regulation in the human soleus (SOL) muscle during controlled lengthening and shortening actions. Eleven subjects performed plantar flexor efforts on an ankle torque motor through 30 degrees of ankle displacement (75 degrees -105 degrees internal ankle angle) at lengthening and shortening velocities of 5, 15 and 30 degrees. S(-1). ⋯ Shortening torques were lower than the isometric level for all conditions. However, whereas SVA and SEA torques decreased at higher velocities of shortening, MVA torques were independent of velocity. These results indicate velocity- and activation-type-specific tension regulation in the human SOL muscle.
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Eur. J. Appl. Physiol. · Feb 2000
Facilitation of the withdrawal reflex by repeated transcutaneous electrical stimulation: an experimental study on central integration in humans.
In the present human study, we aimed to investigate the facilitation of both the subjective pain responses, and the withdrawal reflex to consecutive transcutaneous electrical stimuli as measures of temporal summation. The frequency (0.5-20 Hz) and intensity (0.4-0.8 times the reflex threshold, xRT) of the electrical stimuli were systematically varied. When using repeated stimulation, the stimulus intensity that evoked pain was lower than that required by a single stimulus (temporal summation). ⋯ In conclusion, the results of the present human study demonstrate clearly that a stimulus that is perceived as a localised, repetitive tactile tap can be integrated and cause severe pain. This suggests that pathologically generated sparse nociceptive afferent activity causes strong pain by central integration. This might be one mechanism to explain why clinical conditions can become excruciatingly painful despite the fact that the pathophysiological changes seem to be marginal (e.g. minor nerve trauma).
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Eur. J. Appl. Physiol. · Jan 2000
Influence of complete spinal cord injury on skeletal muscle mechanics within the first 6 months of injury.
In this study we examined the influence of complete spinal cord injury (SCI) on the mechanical characteristics of skeletal muscle in vivo within 6 months of the injury. Surface electrical stimulation (ES) was applied to the left m. quadriceps femoris of patients at 6, 11 and 24 weeks after injury. Surface ES was also applied to seven able-bodied controls (AB) at two time points 18 weeks apart. ⋯ AB, in contrast, showed prolonged relaxation times, with force loss at both time points [115 (10) ms and 113 (11) ms; P = 0.0001]. The results indicate that SCI alters the relaxation but not contractile properties of mixed skeletal muscle within the first 24 weeks of injury. Altered calcium handling and contraction-induced fiber injury are suggested to explain the slower relaxation time per se, and the prolonged relaxation with force loss observed after SCI.