You must be 18 years of age or older and be a healthcare provider, clinician, practitioner (e.g., athletic trainer, physical therapist, physician, physiotherapist, sport scientist, strength and conditioning coach), or a student in a healthcare or sport science-related program that could administer functional testing with patients/clients/athletes to take part in this research study.

• Age 18-85 years
• Fluent in English
• Suspected hearing loss

We invite you to take part in a research study if you are:

• Female sex between 18-40 years old
• Premenopausal with a regular menstrual cycle between 25-35 days and have tracked your menstrual cycle consistently for at least the past three months.
• Willing to wear a Garmin activity tracker device daily including during sleep
• Own a smartphone with the ability to track and sync data via a mobile app
• Not be pregnant, less than 12 months postpartum, or breastfeeding

Additional criteria will be evaluated using an online screener

We invite you to take part in a research study because you are a male runner between the ages of 18 and 40 who has been running at least 4 times per week for the past 3 years and has a recent 5 km personal best under 20 minutes. You must also be:

• Free from injury and able to safely complete treadmill running
• Willing to follow all pre visit restrictions (no caffeine within 24 hours, no strenuous exercise within 24 hours, no food within 3 hours)

• Younger adults aged 18–35 years with a body mass index (BMI) of 18.5–34.9 kg/m² who have participated in lower-body resistance training at least twice per week for the previous 6 months.
• Older adults aged 70 years and older with a body mass index (BMI) of 18.5–34.9 kg/m² who have not participated in lower-body resistance training during the previous 6 months.

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

• Male or female between the ages of 18-40 years old.
• Healthy and ready for physical activity as determined by questionnaires you complete about your health status.
• Currently resistance training and have trained for a minimum of 6 months. To be included, you must have completed 3 resistance training sessions (defined as muscle strengthening activities such as free weights, weight machines, or calisthenics, etc.) per week with at least one lower body session. This will be determined by a Training History Questionnaire (THQ).
• Premenopausal, with a regular menstrual period as determined by the menstrual status questionnaire (female participants only).
• Currently not pregnant and do not intend to become pregnant (female participants
  only).
• Currently not taking dietary supplements that may affect study outcomes (e.g., creatine, beta-alanine) and willing refrain from taking such supplements while enrolled in the study. If you are currently using such supplements, you will be permitted to enroll in the study after not taking such supplements for a period of four weeks.
• Willing to adhere to all pre-testing visit instructions including abstaining from exercise for the duration of the study and abstaining from alcohol for 24 hours prior to each study visit.
• Currently consuming ≤ 300mg caffeine (≤ three 8oz cups of coffee) per day on average and willing to keep caffeine intake consistent throughout the duration of the study. Also willing to avoid caffeine intake for 12 hours prior to visits 3, 4 and 5 and not consume caffeine the morning of these visits.
• Free from previous or current lower body injuries that may limit your ability to complete either exercise or physical assessments.
• Highly likely to be successful at providing the required blood samples. This will be determined during visit 1 by a certified phlebotomist.
• Not regularly taking any type of prescription or over-the-counter medication which might affect the assessments, or having any chronic illnesses, which require medical care. This will be determined in your medical history questionnaire.

• Adults aged 18 to 35 years
• Had lower extremity musculoskeletal surgery within the previous 6 months.
• An age-matched control group of adults without a history of lower extremity musculoskeletal surgery will also be included.

• 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).

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)