Research Study Participation

• are between the ages of 18-35 years,
• either have had an anterior cruciate ligament reconstruction (ACLR) surgery or have not had an injury to either of your knees,
• have not been medically diagnosed with a concussion in the previous 6 months,
• have not been medically diagnosed with colorblindness,
• have no known neurological (nervous system) disorder (i.e. Multiple Sclerosis),
• have not taken opioid medication (pain medication) in the last 2 weeks,
• are not pregnant of planning to become present during study participation, and
• have no contraindications to brain MRI (you will complete a screening form).

Inclusion criteria – ACL group:

• Age 18-35 years
• History of primary unilateral ACL reconstruction (ACLR) within last 2 years
• No history of any lower limb surgery besides the current ACLR
• Medical clearance to initiate jogging

Inclusion criteria – Uninjured group:

• Age 18-35 years
• No history of lower extremity surgery
• No history of lower extremity injury (defined as seeking medical attention) within last 2 years

• Aged 60 years or older
• Have normal cognitive function (based on results from the Mini-Mental State Examination [MMSE] or Telephone Interview for Cognitive Status)
• Are willing to perform grip strength tests and provide informed consent
• Fluent in English

• Be 18-35 years old
• Currently pain free
• English speaking

ACL Group:

• Age of 18-35 years
• History of only one ACL reconstruction within the previous 2 years
• Medical clearance for return to unrestricted activity

Uninjured Group:

• Age of 18-35 years
• No history of lower limb surgery
• No history of significant lower limb injury within previous 6 months (defined as seeking medical attention, or missing >3 consecutive practices or games)

• Ages of 18 and 50 years old.
• Do not have any health-related conditions, diseases, or previous injuries that currently affect your lower extremities.

• At least 18 years old
• A licensed or certified healthcare provider
• A student in an accredited professional healthcare program

• Are an aerobically trained female (≥150 minutes per week of moderate to vigorous aerobic activity) between the ages of 18-35.
• Achieve a peak V̇O₂ of ≥33.6 ml∙kg^-1∙min^-1 on the first visit based on age- and sex-specific normative reference values for cycle ergometry provided by the American College of Sports Medicine
• Are willing to come in for all six visits

• Are a recreationally active (≥150 minutes per week of physical activity) female between the ages of 18-35.
• Are willing to come in for all five visits

• Female between the ages of 40 to 55
• Experiencing variable menstrual cycle length (>7 days different from normal) over the previous 6 months.