The purpose of this study is to investigate pain evoked responses and facilitation of NGF-induced mechanical muscle hyperalgesia over time following an acute exercised-induced ischemic condition in a NGF-sensitized muscle.

Assessing evoked pain responses and muscle hyperalgesia following contractions during acute ischemia in a NGF-sensitized muscle may clarify whether an interaction between NGF sensitization and acidic stimulation exist.

It is hypothesized that acute ischemic exercise with the NGF-sensitized TA muscle, in contrast to ischemic exercise in a non-sensitized would: 1) potentiate pain-evoked responses, and 2) facilitate NGF-induced muscle hyperalgesia.

Inclusion Criteria:

• Healthy and pain free volunteers

Exclusion Criteria:

• Pregnancy
• Drug addiction defined as the use of cannabis, opioids or other drugs
• Previous neurologic, mental illnesses, or psychiatric diseases.
• Past history of chronic pain in the musculoskeletal system (muscle, joint, cartilage, connective tissue)
• Participation in other pain trials throughout the study period
• Lack of ability to cooperate
• Taking any analgesic 24 hours before the injections
• Performing any strenuous leg exercise through out the study period causing sore muscles