Why is it considered dangerous to use painkillers through injections?

Using painkillers through injections is deemed dangerous primarily because they can mask pain, which may lead athletes to continue engaging in activity despite underlying injuries that require rest and treatment. Pain is a crucial signal from the body indicating that something is wrong, and by dulling this sensation, athletes may unknowingly exacerbate the injury, potentially leading to more severe damage. This risk highlights the importance of addressing the root cause of pain rather than simply alleviating the symptom with medication.

In terms of the other choices, while painkillers may have varying effects on performance and could impact the need for physical therapy, these points do not directly address the immediate dangers associated with masking pain through injections. The cost comparison of injections to oral medications is also not central to the inherent risks posed by masking pain, making it less relevant in discussing athlete safety.