Mechanical ventilation in rabbits produces alterations in contractile properties of the diaphragm and 5th external intercostal muscle, increases both muscles fatigue, and promotes atrophy of type II fibers.

In order to assess the effects of FES on muscle output, chronic electrical stimulation of the quadriceps muscle was applied for half an hour twice a day for 2 months, in 10 thoracic level traumatic paraplegic patients. Results concerning torque (at 6 different muscle lengths) and fatigue were measured using a strain gauge transducer in isometric condition, and compared with the findings in 15 paraplegic patients who had not received electrical stimulation, and with 10 able bodied subjects with normal motor functions. With training, muscle strength was very significantly improved whilst fatigue resistance re mained at a low level. The peak torque was not found to be of the same muscle length when comparing paraplegics and control subjects; it seemed to demon strate that length-tension relationship of the muscular actuator was changing when it was electrically activated. Moreover, the force recorded in paraplegics remained markedly lower than in able bodied people.

No abstract

We assessed the length-tension relationship of the posterior deltoid to triceps transfer in 8 tetraplegics (n = 11 transfers) and compared the results to the length-tension relationship of the normal triceps measured in a check sample composed of 9 able bodied, right handed women. We designed a device to lock the arm and forearm and used a force transducer to assess the torque output isometrically. The muscle was tested at 6 different lengths (130, 110, 90, 70, 45 and 0° of elbow flexion) with the shoulder abducted at 90°. As expected, the transfer behaved differently from the normal triceps. The mean maximum torque recorded was 7. 8 Nm in patients while it was 27 Nm in the check sample. When compared, the absolute values (ie values expressed with a dimension of torque) were significantly different between groups (0. 00001 < P < 0. 002). The expression of this relation (ie the relative values expressed as percentage of maximum values) revealed significant statistical differences (p < 0. 002) at 90 and 70° of elbow flexion; the peak torque was recorded at 130° in patients while it was recorded at 110° in the check sample, with a plateau between 110° and 70°. On the other hand, if the length-tension relationship was fairly similar among subjects of the check sample, it exhibited tremendous differences among patients; it seemed that initial tension given by the surgeon represented a variable difficult to control without a device dedicated to that task.