You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Cellmass.jpg|2618" />
  </query-continue>
  <query>
    <pages>
      <page pageid="138" ns="0" title="Бицепс - упражнения и особенности тренировки" />
      <page pageid="245" ns="0" title="Бодибилдинг, атлетизм и гиревой спорт (Кочетков)" />
      <page pageid="408" ns="0" title="BCAA" />
      <page pageid="498" ns="0" title="Бодибилдинг современный подход (Хрипач)" />
      <page pageid="1054" ns="0" title="Акне" />
      <page pageid="1206" ns="0" title="Bromelain" />
      <page pageid="1701" ns="0" title="Ацетил-L-карнитин" />
      <page pageid="2614" ns="0" title="Капсаицин" />
      <page pageid="2620" ns="0" title="CM2 Alpha от SAN" />
    </pages>
  </query>
</api>