No, actually they contract.
Not to get too technical, but the unit of muscle contraction is called the sarcomere. Think of two filaments, thick and thin, situated somewhat like this.
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Those brackets on the bottom are the myosin heads on the thick filament. There are thousands to millions of these units bundled in skeletal muscles. Those myosin heads reach up to that thin filament above and push in unison, which contracts that sarcomere unit, plus all the other units in unison, thus contracting your skeletal muscles.