Acute and Prolonged Effects of 300 sec of Static, Dynamic, and Combined Stretching on Flexibility and Muscle Force

Abstract

Static stretching (SS), dynamic stretching (DS), and combined stretching (CS; i.e., DS+SS) are commonly performed as warm-up exercises. However, the stretching method with the greatest effect on flexibility and performance remains unclear. This randomized crossover trial examined acute and prolonged effects of SS, DS, and CS on range of motion (ROM), peak passive torque (PPT), passive stiffness, and isometric and concentric muscle forces. Twenty healthy young men performed 300 sec of active SS, DS, or CS (150-sec SS followed by 150-sec DS and 150-sec DS followed by 150-sec SS) of the right knee flexors on four separate days, in random order. Subsequently, we measured ROM, PPT, and passive stiffness during passive knee extension. We also measured maximum voluntary isometric and concentric knee flexion forces and surface electromyographic activities during force measurements immediately before, immediately after, and 20 and 60 min after stretching. All stretching methods significantly increased ROM and PPT, while significantly decreasing isometric knee flexion force (all p < 0.05). These changes lasted 60 min after all stretching methods; the increases in ROM and PPT and the decreases in isometric muscle force were similar. All stretching methods also significantly decreased passive stiffness immediately after stretching (all p < 0.05). Decreases in passive stiffness tended to be longer after CS than after SS or DS. Concentric muscle force was decreased after SS and CS (all p < 0.05). On the other hand, concentric muscle force was unchanged after DS, while the decreases in surface electromyographic activities during concentric force measurements after all stretching methods were similar. Our results suggest that 300 sec of SS, DS, and CS have different acute and prolonged effects on flexibility and muscle force.

Keywords: Warm-up exercise; muscle performance; passive stiffness; passive torque; range of motion; retention time.

Figure 1.

Randomized crossover study design. Prior to the first testing day, all participants attended a familiarization session in which they learned and practiced all stretching methods and measurements. Participants completed measurement sessions on four separate days, one for each stretching type (SS, DS, SS-DS, DS-SS) in random order. SS, static stretching; DS, dynamic stretching; SS-DS, static stretching followed by dynamic stretching; DS-SS, dynamic stretching followed by static stretching.

Figure 2.

Stretching procedures. (a) Static stretching: Each participant assumed a standing upright position and placed their right heel (with an extended leg) on a 50-cm-high platform. The participant then reached forward with their arms toward the extended leg while maintaining a proper lordotic curve. (b) Dynamic stretching: Each participant assumed a standing upright position, then intentionally contracted the right hip flexors with the knee extended and flexed their right hip joint so that their right leg swung up to the anterior aspect of their body.

Figure 3.

Sitting positions for measurements of dependent variables. (a) Flexed position for measurements of torque–angle relationship and isometric muscle force: Each participant was seated on a chair with the seat maximally tilted and a wedge-shaped cushion inserted between the trunk and the backrest. (b) Horizontal position for the measurements of isometric and concentric muscle force: Each participant was seated on a chair with the seat adjusted parallel to the floor and a wedge-shaped cushion inserted between the trunk and the backrest.