TY - JOUR

T1 - Altered Triceps Surae Muscle-Tendon Unit Properties after 6 Months of Static Stretching

AU - Moltubakk, Marie M.

AU - Villars, Fabienne O.

AU - Magulas, Melina M.

AU - Magnusson, Stig P.

AU - Seynnes, Olivier R.

AU - Bojsen-Moller, Jens

PY - 2021

Y1 - 2021

N2 - Introduction This study examined the effects of 24 wk of daily static stretching of the plantarflexors (unilateral 4 x 60-s stretching, whereas the contralateral leg served as a control; n = 26) on joint range of motion (ROM), muscle-tendon unit morphological and mechanical properties, neural activation, and contractile function. Methods Torque-angle/velocity was obtained in passive and active conditions using isokinetic dynamometry, whereas muscle-tendon morphology and mechanical properties were examined using ultrasonography. Results After the intervention, ROM increased (stretching, +11 degrees +/- 7 degrees; control, 4 degrees +/- 8 degrees), and passive torque (stretching, -10 +/- 11 N center dot m; control, -7 +/- 10 N center dot m) and normalized EMG amplitude (stretching, -3% +/- 6%; control, -3% +/- 4%) at a standardized dorsiflexion angle decreased. Increases were seen in passive tendon elongation at a standardized force (stretching, +1.3 +/- 1.6 mm; control, +1.4 +/- 2.1 mm) and in maximal passive muscle and tendon elongation. Angle of peak torque shifted toward dorsiflexion. No changes were seen in tendon stiffness, resting tendon length, or gastrocnemius medialis fascicle length. Conformable changes in ROM, passive dorsiflexion variables, tendon elongation, and angle of peak torque were observed in the nonstretched leg. Conclusions The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering muscle-tendon behavior with the potential to modify contractile function.

AB - Introduction This study examined the effects of 24 wk of daily static stretching of the plantarflexors (unilateral 4 x 60-s stretching, whereas the contralateral leg served as a control; n = 26) on joint range of motion (ROM), muscle-tendon unit morphological and mechanical properties, neural activation, and contractile function. Methods Torque-angle/velocity was obtained in passive and active conditions using isokinetic dynamometry, whereas muscle-tendon morphology and mechanical properties were examined using ultrasonography. Results After the intervention, ROM increased (stretching, +11 degrees +/- 7 degrees; control, 4 degrees +/- 8 degrees), and passive torque (stretching, -10 +/- 11 N center dot m; control, -7 +/- 10 N center dot m) and normalized EMG amplitude (stretching, -3% +/- 6%; control, -3% +/- 4%) at a standardized dorsiflexion angle decreased. Increases were seen in passive tendon elongation at a standardized force (stretching, +1.3 +/- 1.6 mm; control, +1.4 +/- 2.1 mm) and in maximal passive muscle and tendon elongation. Angle of peak torque shifted toward dorsiflexion. No changes were seen in tendon stiffness, resting tendon length, or gastrocnemius medialis fascicle length. Conformable changes in ROM, passive dorsiflexion variables, tendon elongation, and angle of peak torque were observed in the nonstretched leg. Conclusions The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering muscle-tendon behavior with the potential to modify contractile function.

KW - FLEXIBILITY

KW - PASSIVE RESISTANCE

KW - LENGTH TENSION

KW - ULTRASOUND

KW - STRETCH TOLERANCE

KW - MECHANICAL-PROPERTIES

KW - MEDIAL GASTROCNEMIUS

KW - BICEPS FEMORIS

KW - TENSION

KW - MOTION

KW - LENGTH

KW - RANGE

KW - EXTENSIBILITY

KW - ARCHITECTURE

U2 - 10.1249/MSS.0000000000002671

DO - 10.1249/MSS.0000000000002671

M3 - Journal article

C2 - 34398062

VL - 53

SP - 1975

EP - 1986

JO - Medicine and Science in Sports and Exercise

JF - Medicine and Science in Sports and Exercise

SN - 0195-9131

IS - 9

ER -