THE ACUTE EFFECTS OF STATIC AND DYNAMIC STRETCHING ON PASSIVE TORQUE,

MAXIMAL VOLUNTARY CONTRACTION AND RANGE OF MOTION IN THE

BY JAMES GAVIN AND CHRISTOPHER MORSE, DEPARTMENT OF EXERCISE AND SPORT SCIENCE, MANCHESTER METROPOLITAN UNIVERSITY

INTRODUCTION Passive stretching methods are used to increase limb range of motion (ROM) and prepare the musculoskeletal system before physical activity. Research suggests that static stretching may be detrimental to activities requiring rapid force generation and maximal force output (1). Static stretches of certain duration may transiently reduce the passive torque (stiffness) of the musculotendinous unit (MTU) as the MTUs become more compliant and are unable to transmit force as efficiently (2). These findings have led to the use of dynamic stretching within warm-ups, as dynamic stretching can be more specific to movement patterns found in the sporting domain.

PURPOSE To further investigate the effects of warm-up routines by comparing the acute influence of static and dynamic conditioning stretches on passive torque, maximal force production, ROM and electromyography (EMG) of the plantarflexors.

METHODS Following institutional ethics approval, passive torque

35 30 25 20 15

10 0 5 10 Ankle angle (deg) Figure 1: Plantarflexor isokinetic dynamonetry 22

Figure 2: Passive torque during a standard measurement stretch pre and post conditioning after static stretching

sportEX dynamics 2009;21(Jul):18-23 15 20 Pre static static Conditioning

and ROM of the plantarflexor

muscle group were

measured by isokinetic dynamometry in

10 male participants (mean±standard

deviation (SD): age 21±1.8 years). Passive torque and ROM were

quantified using a standard stretch in which the ankle was passively dorsiflexed at 1°s-1 (0.017rad·s-1) from 10°

plantarflexion to the participant’s volitional end ROM. Plantarflexor one repetition maximum (1RM) torque and EMG were also measured using an isometric

maximal voluntary contraction (MVC). Standard stretch and MVC measures were recorded before and after either or dynamic conditioning stretches. protocols were administered passively

using an isokinetic dynamometer. Static conditioning consisted of five 1-minute static stretches held at the participant’s maximal dorsiflexion angle. Dynamic conditioning involved 20 cyclic stretches at a velocity of 30°s-1 (0.52rad·s-1) through the participant’s predetermined ROM.

DATA ANALYSIS A two-way (2×4) mixed measures analysis of variance (ANOVA) examined variable differences before and after static and dynamic conditioning.

KEY FINDINGS n Following static conditioning, ROM significantly increased (P<0.001) by 5.4±3.4° (23.1%); dynamic conditioning produced an increase of 2±1.2° (8.4%). n Plantarflexor passive torque decreased (between 10° and 20°) significantly after static conditioning (P<0.02), whereas no significant difference was seen with dynamic conditioning (P>0.8). n Before and after static and dynamic conditioning, there

Post static

Passive torque (Nm)