Abstract:

BACKGROUND: Studies concerning trunk muscles mainly focus on muscle strength changes in patients with low back pain, which is rare regarding angle ranges that easily lead to spinal injury.
OBJECTIVE: To explore the mechanics characteristic of flexor-extensor and angle ranges easily lead to spinal injury.
METHODS: Fourteen healthy, male, post-graduates of Soochow University were selected. Flexor-extensor strength and spinal angle of participants were measured using CON-TREX isokinetic testing system. All participants took isokinetic centrifugal exercise maximally at the speeds of 30, 60, 90, 120, 180 (°)/s, respectively, with a 5 minutes interval. Main outcome measures: ①Lumbar range of motion; ②Peak torque, flexor/extensor, the angle at peak torque at isokinetic centripetal exercise; ③Average power and total work at isokinetic centripetal exercise.
RESULTS AND CONCLUSION:  ①During isokinetic centripetal exercise, the peak torque of extensor were decreased as the geniovelocity increased (P < 0.05), however, no inerratic changes could be found in flexor peak torque. Though the flexor/extensor was increased with geniovelocity increased, the difference had no significance (P > 0.05). ②During slow isokinetic centripetal exercise underwent different geniovelocity, the angle at peak torque of flexor and extensor distributed discretely, -48.56° at 30 (°)/s; -46.18° at 90 (°)/s; when underwent fast isokinetic exercise, the angles at peak torque of flexor and extensor were very close, which were -48.71° and -51.61° at 120 (°)/s, and -54.86° and -53.11° at 180 (°)/s. ③During isokinetic centripetal exercise, when underwent different geniovelocity, total work of flexor and extensor was reduced with geniovelocity expedited, extensor total work was more than that of flexor (P < 0.05); the average power of flexor and extensor was increased linearly with geniovelocity expedited, and the average power of flexor was less than that of extensor all along (P < 0.01). During isokinetic centripetal exercise, trunk muscle strength descended with the geniovelocity expedited, and the stability of trunk is preferable in slow exercise. During fast isokinetic centripetal exercise, angles at flexor and extensor peak torque are more discrete, which easily result in muscle damages and spine unstable when suffered a suddenly outside attack. Total work of flexor and extensor are descended with the geniovelocity expediting during isokinetic exercise, but the intramuscular eruption increased.