<span>It is a vacuum effect. The lungs have gotten used to their size and shape, and they are comfortable this way. When a person forcibly exhales, it constricts the lungs. When a person relaxes, the lungs return to their normal shape as they took in air. The only ventilation is the trachea, and it forces air in.</span>
<em>=</em><em>The</em><em> </em><em>two</em><em> </em><em>techniques</em><em> </em><em>for</em><em> </em><em>putting</em><em> </em><em>a </em><em>shot </em><em>are</em><em> </em><em>:</em>
<em>1</em><em>.</em><em>use </em><em>the</em><em> </em><em>Spin.</em>
<em>2</em><em>.</em><em> </em><em>The</em><em> </em><em>glide </em><em>technique</em><em>.</em>