Final answer:
Elevated levels of lactic acid are produced during submaximal swimming, resulting in fatigue. However, fatigue is not solely caused by lactic acid levels, but rather a combination of different factors.
Step-by-step explanation:
Elevated levels of lactic acid are produced during submaximal swimming, resulting in fatigue. However, the fatigue experienced during swimming is not solely caused by lactic acid levels, but rather a combination of different factors. These factors include energy availability, oxygen delivery, perception to pain, and other psychological factors. While lactic acid buildup may contribute to muscle fatigue, it is not the only factor at play.