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ABSTRACT.
Skof, B., and V. Strojnik. The effect of two warm-up protocols on some biomechanical parameters of the neuromuscular system of middle distance runners. J. Strength Cond. Res. 21(2):394-399. 2007.-The objective of this study was to determine the effect of 2 different warm-up protocols on the neuromuscular system of well-trained middle distance runners. Seven runners performed 2 different warm-up protocols, one of which included slow running, stretching, and bounding and sprinting exercises, while the other consisted of slow running and stretching only. Before and after warm-up, contractile properties of the vastus lateralis and quadriceps femoris were monitored with a single twitch test, maximal torque, and the level of muscle activation during maximal voluntary extension. The 2 types of warm-up protocols showed statistically significant differences in the increase of peak knee extension torque and muscle activation level. After warm-up 1 maximal twitch torque was increased and twitch contraction time (CT) was shortened. Both maximal torque and the level of activation were increased. Parameter changes after warm-up 2 were similar to those after warm-up 1 but not statistically significant. Sprinting and bounding as part of athletes' warm-up improve muscle activation.
KEY WORDS. warm up, muscle contractile functions, electrical stimulation
INTRODUCTION
A runner's efficiency depends on different combinations of aerobic and anaerobic power and capacity, running economy, neuromuscular characteristics, and muscular strength. Warm-up is used by athletes to activate their biological and psychological potential and achieve such a physiological and psychological state as to ensure optimum competitive efficiency. Several studies (1, 21, 24, 25, 28, 32) confirm the connection between different physiological and biochemical changes in the body after warming up, and enhanced competitive efficiency. Competitive loads of different intensity require different, i.e., specific, preparation. Different techniques of warm-up protocols (active, passive) as well as different intensity and duration result in different physiological-biochemical changes in the body (8, 9, 13, 26, 28).
In addition to optimal metabolic circumstances, racing velocity in middle distance running (i.e., 800-3,000 meters; 6.5 to 8 m-s^sup -1^) and other intensive short-term workloads requires a suitable preparation of the neuromuscular system that enhances the mechanical efficiency of work (29).
The effects of warm-up on the neuromuscular system can be observed on 2 levels:
* The effectiveness of peripheral mechanisms is increased. Raised muscle...