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Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus

Device and parameters for lengthening contraction (LC). (A) Device and experimental setup for loading LC. The animal is placed on a table under inhalation anesthesia with 1.5% isoflurane. Repetitive electrical stimulation of the tibialis anterior (TA) via surface electrodes induces dorsiflexion of a paw attached to a foot plate (a). The planta pedis was double‐stick taped on the foot plate of the device, and the foot and plate was further wrapped with a heat shrinkable tube. The extensors are repetitively stretched by a stepping motor (c) driven by signals from a computer via a control box (d). These stretch loads are synchronized with electrical stimulation (e) (and thus with dorsiflexion) for LC. A sensor (b) detects the torque generated during LC. (B) An enlarged image of the square area in A. Before triggering LC, the ankle joint was passively moved and positioned at the starting position (30° of dorsiflexion, i.e., the angle formed where the Line 2 and 3 cross each other is 60°). Line 2 connects 2 bony landmarks, the head of the fibula and lateral malleolus, and Line 3 connects the lateral malleolus and the head of the 5th metatarsal bone. The axis of joint rotation is 3 mm in front of the lateral malleolus of the fibula. The ankle joint was plantarflexed (stretched) to 90° from the starting position at angular velocities of 50, 100, 200, and 400 deg/sec while the ankle extensor muscles were contracted by electrical stimulation. (C) Schedule for applying LC and change in torque generated during LC at an angular velocity of 200 deg/sec. Each LC trail was repeated 10 times every 10 sec for 1 set. Sets were repeated every 60 sec to a total of 5. (D) A torque curve generated by the 5th LC in the first set is shown in (c). ES: electrical stimulation. A delay of 200 msec was set from the start of ES to the onset of torque generation by LC. (E) The time line of this experiment is shown. We produced the model of injured rats (n = 23) by lengthening contraction (LC) of the anterior tibial muscle (TA). Evans blue dye was administered 24 h after LC. Forty‐eight hours after LC, the maximum isometric dorsiflexion torque of the ankle joint was measured (MFT, muscle function test) and calculated the rate of change from torque value for preinjury. TA muscle was finally removed 48 h after LC for histological analyses.
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fig01: Device and parameters for lengthening contraction (LC). (A) Device and experimental setup for loading LC. The animal is placed on a table under inhalation anesthesia with 1.5% isoflurane. Repetitive electrical stimulation of the tibialis anterior (TA) via surface electrodes induces dorsiflexion of a paw attached to a foot plate (a). The planta pedis was double‐stick taped on the foot plate of the device, and the foot and plate was further wrapped with a heat shrinkable tube. The extensors are repetitively stretched by a stepping motor (c) driven by signals from a computer via a control box (d). These stretch loads are synchronized with electrical stimulation (e) (and thus with dorsiflexion) for LC. A sensor (b) detects the torque generated during LC. (B) An enlarged image of the square area in A. Before triggering LC, the ankle joint was passively moved and positioned at the starting position (30° of dorsiflexion, i.e., the angle formed where the Line 2 and 3 cross each other is 60°). Line 2 connects 2 bony landmarks, the head of the fibula and lateral malleolus, and Line 3 connects the lateral malleolus and the head of the 5th metatarsal bone. The axis of joint rotation is 3 mm in front of the lateral malleolus of the fibula. The ankle joint was plantarflexed (stretched) to 90° from the starting position at angular velocities of 50, 100, 200, and 400 deg/sec while the ankle extensor muscles were contracted by electrical stimulation. (C) Schedule for applying LC and change in torque generated during LC at an angular velocity of 200 deg/sec. Each LC trail was repeated 10 times every 10 sec for 1 set. Sets were repeated every 60 sec to a total of 5. (D) A torque curve generated by the 5th LC in the first set is shown in (c). ES: electrical stimulation. A delay of 200 msec was set from the start of ES to the onset of torque generation by LC. (E) The time line of this experiment is shown. We produced the model of injured rats (n = 23) by lengthening contraction (LC) of the anterior tibial muscle (TA). Evans blue dye was administered 24 h after LC. Forty‐eight hours after LC, the maximum isometric dorsiflexion torque of the ankle joint was measured (MFT, muscle function test) and calculated the rate of change from torque value for preinjury. TA muscle was finally removed 48 h after LC for histological analyses.

Mentions: Under inhalation anesthesia with 1.5% isoflurane, ankle extensor muscles were subjected to repetitive LC using a customized device (NDH‐1; Bio Research Center, Co., Ltd., Nagoya, Japan) that precisely controls stretch parameters (Fig. 1A). Left dorsiflexor muscles of the hind leg were percutaneously stimulated via a pair of surface electrodes fixed with a quick‐drying glue over the tibialis anterior (TA) muscle (Fig. 1B), and maximal dorsiflexion was evoked using supramaximal tetanic current (1 msec pulses at 100 Hz, constant current of 5 mA) supplied through an isolator (SS‐202J; Nihon Kohden Corp., Japan) connected to an electrical stimulator (SEN‐3301; Nihon Kohden Corp., Tokyo, Japan.). The movement of a foot plate was synchronized with the electrical stimulator so that the muscles were stretched while they were being activated. Three axes were drawn so that the range of motion during LC could be precisely defined: the femoral axis (Line 1 between the third trochanter and lateral condyle of the femur), fibular axis (Line 2 between the head and lateral malleolus of the fibula) and foot axis (Line 3 along the base of metatarsal; Fig. 1B). Based on these axes, knee, and ankle joints were set at 90° and 60°, respectively, just before triggering LC. The center of the moment arm of the ankle joint during LC was set 3 mm in front of lateral malleolus of the fibula. LC was induced at angular velocities of 50, 100, 200, and 400 deg/sec with simultaneous stimulus trains of 2000, 1100, 650, and 425 msec, respectively. There was a 200 msec delay from the start of electrical stimulation to the onset of applied torque generation for LC (Fig. 1D, marked by the left thick dotted vertical line). Lengthening contraction was applied over 90° from the starting position (ankle joint dorsiflexed 30°). One LC set was composed of 10 contractions every 10 sec. Five sets were acquired per animal at 60 sec intervals (Fig. 1C). Torque generated in response to electrical stimuli was continuously recorded during LC (Fig. 1C and D), and the peak value was measured at different angular velocities.


Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Device and parameters for lengthening contraction (LC). (A) Device and experimental setup for loading LC. The animal is placed on a table under inhalation anesthesia with 1.5% isoflurane. Repetitive electrical stimulation of the tibialis anterior (TA) via surface electrodes induces dorsiflexion of a paw attached to a foot plate (a). The planta pedis was double‐stick taped on the foot plate of the device, and the foot and plate was further wrapped with a heat shrinkable tube. The extensors are repetitively stretched by a stepping motor (c) driven by signals from a computer via a control box (d). These stretch loads are synchronized with electrical stimulation (e) (and thus with dorsiflexion) for LC. A sensor (b) detects the torque generated during LC. (B) An enlarged image of the square area in A. Before triggering LC, the ankle joint was passively moved and positioned at the starting position (30° of dorsiflexion, i.e., the angle formed where the Line 2 and 3 cross each other is 60°). Line 2 connects 2 bony landmarks, the head of the fibula and lateral malleolus, and Line 3 connects the lateral malleolus and the head of the 5th metatarsal bone. The axis of joint rotation is 3 mm in front of the lateral malleolus of the fibula. The ankle joint was plantarflexed (stretched) to 90° from the starting position at angular velocities of 50, 100, 200, and 400 deg/sec while the ankle extensor muscles were contracted by electrical stimulation. (C) Schedule for applying LC and change in torque generated during LC at an angular velocity of 200 deg/sec. Each LC trail was repeated 10 times every 10 sec for 1 set. Sets were repeated every 60 sec to a total of 5. (D) A torque curve generated by the 5th LC in the first set is shown in (c). ES: electrical stimulation. A delay of 200 msec was set from the start of ES to the onset of torque generation by LC. (E) The time line of this experiment is shown. We produced the model of injured rats (n = 23) by lengthening contraction (LC) of the anterior tibial muscle (TA). Evans blue dye was administered 24 h after LC. Forty‐eight hours after LC, the maximum isometric dorsiflexion torque of the ankle joint was measured (MFT, muscle function test) and calculated the rate of change from torque value for preinjury. TA muscle was finally removed 48 h after LC for histological analyses.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig01: Device and parameters for lengthening contraction (LC). (A) Device and experimental setup for loading LC. The animal is placed on a table under inhalation anesthesia with 1.5% isoflurane. Repetitive electrical stimulation of the tibialis anterior (TA) via surface electrodes induces dorsiflexion of a paw attached to a foot plate (a). The planta pedis was double‐stick taped on the foot plate of the device, and the foot and plate was further wrapped with a heat shrinkable tube. The extensors are repetitively stretched by a stepping motor (c) driven by signals from a computer via a control box (d). These stretch loads are synchronized with electrical stimulation (e) (and thus with dorsiflexion) for LC. A sensor (b) detects the torque generated during LC. (B) An enlarged image of the square area in A. Before triggering LC, the ankle joint was passively moved and positioned at the starting position (30° of dorsiflexion, i.e., the angle formed where the Line 2 and 3 cross each other is 60°). Line 2 connects 2 bony landmarks, the head of the fibula and lateral malleolus, and Line 3 connects the lateral malleolus and the head of the 5th metatarsal bone. The axis of joint rotation is 3 mm in front of the lateral malleolus of the fibula. The ankle joint was plantarflexed (stretched) to 90° from the starting position at angular velocities of 50, 100, 200, and 400 deg/sec while the ankle extensor muscles were contracted by electrical stimulation. (C) Schedule for applying LC and change in torque generated during LC at an angular velocity of 200 deg/sec. Each LC trail was repeated 10 times every 10 sec for 1 set. Sets were repeated every 60 sec to a total of 5. (D) A torque curve generated by the 5th LC in the first set is shown in (c). ES: electrical stimulation. A delay of 200 msec was set from the start of ES to the onset of torque generation by LC. (E) The time line of this experiment is shown. We produced the model of injured rats (n = 23) by lengthening contraction (LC) of the anterior tibial muscle (TA). Evans blue dye was administered 24 h after LC. Forty‐eight hours after LC, the maximum isometric dorsiflexion torque of the ankle joint was measured (MFT, muscle function test) and calculated the rate of change from torque value for preinjury. TA muscle was finally removed 48 h after LC for histological analyses.
Mentions: Under inhalation anesthesia with 1.5% isoflurane, ankle extensor muscles were subjected to repetitive LC using a customized device (NDH‐1; Bio Research Center, Co., Ltd., Nagoya, Japan) that precisely controls stretch parameters (Fig. 1A). Left dorsiflexor muscles of the hind leg were percutaneously stimulated via a pair of surface electrodes fixed with a quick‐drying glue over the tibialis anterior (TA) muscle (Fig. 1B), and maximal dorsiflexion was evoked using supramaximal tetanic current (1 msec pulses at 100 Hz, constant current of 5 mA) supplied through an isolator (SS‐202J; Nihon Kohden Corp., Japan) connected to an electrical stimulator (SEN‐3301; Nihon Kohden Corp., Tokyo, Japan.). The movement of a foot plate was synchronized with the electrical stimulator so that the muscles were stretched while they were being activated. Three axes were drawn so that the range of motion during LC could be precisely defined: the femoral axis (Line 1 between the third trochanter and lateral condyle of the femur), fibular axis (Line 2 between the head and lateral malleolus of the fibula) and foot axis (Line 3 along the base of metatarsal; Fig. 1B). Based on these axes, knee, and ankle joints were set at 90° and 60°, respectively, just before triggering LC. The center of the moment arm of the ankle joint during LC was set 3 mm in front of lateral malleolus of the fibula. LC was induced at angular velocities of 50, 100, 200, and 400 deg/sec with simultaneous stimulus trains of 2000, 1100, 650, and 425 msec, respectively. There was a 200 msec delay from the start of electrical stimulation to the onset of applied torque generation for LC (Fig. 1D, marked by the left thick dotted vertical line). Lengthening contraction was applied over 90° from the starting position (ankle joint dorsiflexed 30°). One LC set was composed of 10 contractions every 10 sec. Five sets were acquired per animal at 60 sec intervals (Fig. 1C). Torque generated in response to electrical stimuli was continuously recorded during LC (Fig. 1C and D), and the peak value was measured at different angular velocities.

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus