Firstly look if there was an indoor or monitored ice-skating rink in the local area; if looking for a natural place to ice-skate, ice must be at a temperature of <span>−3.5 °C or lower, for safe skating. You must look for the correct temperature and weather conditions. </span>
The direct object would have to be the muscle's ability because it answers the question "what".
e.g: Exercise can increase what? The muscle's ability.
The Grapes of Wrath<span> by John Steinbeck - An </span>Excerpt<span>. Once California belonged to Mexico and its land to Mexicans; and a horde of tattered feverish Americans poured in. ... The Mexicans were weak and fled. They could not resist, because they wanted nothing in the world as frantically as the Americans wanted land.</span>