Effect of Static Stretching on Maximal Voluntary Contraction & Force-Time Curve Characteristics

Stretching is used to increase the range of motion around the joint, prevent injury, and also is recommended to improve athletic performance; however, recent investigators have reported that acute and prolonged stretching may reduce athletic performance through decrements in strength, power, vertical jump and sprint performance, balance, and movement time.

The stretch-induced decreases in force have been attributed to both neural (motor unit activation, firing frequency, and reflex sensitivity) and/or mechanical factors (muscle stiffness).

The Objective of the Study

To examine the effect of static stretching of the lower limbs on maximal voluntary contraction (MVC) and isometric force-time curve characteristics of leg extensor muscles, and electromyography (EMG) activity of rectus femoris, biceps femoris, and gastrocnemius.

How the Study is Designed

A within subjects experimental design. Participants: Ten healthy physical education students (age, 19.7 ± 1.4 years; height, 177 ± 4.8 cm; body mass, 72.6 ± 8.4 kg) were tested after jogging and a jogging/stretch protocol of the lower limbs.

The stretching protocol involved a 10 min jog and seven static stretching exercises for the major muscle groups of the lower limbs.

What the Results Showed

Measurements included the maximal voluntary contraction (MVC) of leg extensors, the time achieved to the MVC (TMVC), the force exerted during the first 100ms of the contraction (F100), the index of relative force (IRF), the index of force development rate (IFDR), and the average integrated EMG activity (AEMG) of the rectus femoris, biceps femoris, and gastrocnemius.

There were slight but no significant changes in MVC (1%), TMVC (4.8%), F100 (7.8%), IRF (1%), and IFDR (3.5%) between jogging and jogging/stretch measurement. A significant difference (21%; P<0.05) in AEMG of rectus femoris was found between jogging and jogging/stretch mea- surement, whereas AEMG of biceps femoris and gastrocnemius were unaltered.

Players Stretching

Practical Application

  • In conclusion, a moderate volume and duration of static stretching of the lower limbs resulted in nonsignificant decrements in MVC and isometric force-time curve characteristics, whereas EMG activity of the rectus femoris was decreased.

 

  • Neural inhibition, as it is reflected from EMG activity, did not alter the MVC and isometric force-time curve characteristics.

 

  • These findings suggest that a moderate duration of static stretching must be preferred when the goal of a rehabilitation program is the strength and power development.

 

  • On the other hand, when the goal of the rehabilitation process is the maximal motor unit activation, stretching exercises should be reduced.

 

  • Further research is needed to examine the effect of stretching on muscle strength and force-time curve characteristics in order to maximize the benefits of warming up in sports performance and rehabilitation development.

 

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