The overall objective of this pilot study is to establish the feasibility and methodological validity of using high-density surface electromyography to characterize motor unit behavior of the quadriceps under thermoneutral and locally cooled conditions, and to generate preliminary data to inform the design of a larger, hypothesis-driven study.

This randomized, cross-over pilot study will recruit 24 healthy young adults (12 men and 12 women) between the ages of 18 and 35 years. Participants will attend two in-person laboratory visits separated by a minimum of 48 hours. Visit 1 will include informed consent, eligibility confirmation, baseline assessments, and familiarization procedures. Visit 2 will include experimental testing under thermoneutral and cooled conditions.

Inclusion Criteria:

• Men and women between the ages of 18 and 35 years
• Healthy adults, defined as absence of significant acute/chronic medical condition, injury, and/or illness that may compromise subject safety, limit the ability of the participant to complete the study, and/or compromise the objectives of the study as determined by the Principal Investigator.

Exclusion Criteria:

• Current diagnosis or history of:

  • major metabolic disease (e.g., type I and type II diabetes),
  • neuromuscular disease (e.g., cervical spondylotic radiculomyelopathy, lumbar spondylosis, amyotrophic lateral sclerosis, Guillain-Barré syndrome, and acquired demyelinating polyneuropathies),
  • cardiovascular disease (e.g., stage II hypertension, heart failure, myocardial infarction/ischemia, peripheral vascular disease, Raynaud's phenomenon, or other conditions associated with impaired peripheral circulation),
  • significant myocardial or pericardial diseases (e.g. amyloidosis, constriction),
  • moderate or severe valvular disease,
  • pulmonary/respiratory disease (e.g., asthma, chronic bronchitis, emphysema, chronic obstructive pulmonary disease),
  • cancer,
  • renal disease,
  • liver disease,
  • or anemia.

• Current or recent musculoskeletal injury (e.g. fracture, sprain, dislocation) or any physical disability that precludes safe and adequate testing.

• Pregnancy or breastfeeding.

• Thigh circumference greater than 23 inches

• Mid-thigh skinfold thickness greater 40 mm