A Comparison of Neuromuscular Recruitment in Trained and Untrained Adults

Summary

The objective of the study is to use neurological techniques to obtain quantitative measurements of nervous system control of skeletal muscle activity in adults aged 60-85 who are either long-term resistance exercisers or who are untrained.

Conditions

• Healthy
• Insulin Resistance

Interventions

DIAGNOSTIC_TEST

Neuromuscular Test

To measure neuromuscular connectivity, Transcranial Magnetic Stimulation (TMS) will be used to stimulate regions of the cerebral cortex known to control specific muscles. Electromyography (EMG) activity will then be measured from the following muscle groups: deltoid, biceps, extensor digitorum communis, abductor pollicis brevis, abductor digiti minimi, and first dorsal interosseous muscle.

DIAGNOSTIC_TEST

DEXA

The DEXA test uses X-rays to measure how many grams of calcium and other bone minerals are packed into a segment of bone. The test also measures the amount of fat-free mass, and fat mass.

DIAGNOSTIC_TEST

Mixed Meal Tolerance Test

Fasting blood will be collected for glucose, insulin, and c-peptide. Participants will be provided with a milkshake with a fixed amount of protein, carbohydrates, and fat. Glucose, insulin, and c-peptide will be measured at multiple time points (every 10 minutes) until four hours after consumption (50% Fat, 30% Carbohydrate HO, 20% Protein). Approximately 70mls of blood will be drawn during this time

DIAGNOSTIC_TEST

Strength Test

Knee extensor strength will be tested by gradually increasing the workload on a pneumatic Keiser knee extension machine. The test will begin with a warm-up of 4-5 reps with one leg at 30-50 psi. Then the participant will increase the workload at self-selected intervals ranging from 5-20psi until a maximum effort is achieved. If a rep is failed, then the workload will be reduced by 5psi until a successful rep is performed or a workload is reached in which a successful rep had been previously achieved. Handgrip strength will be tested using a handheld dynamometer (Baseline® standard hydraulic hand dynamometer). The test is performed with the participant seated with the elbow unsupported and flexed at 90 degrees, forearm neutral, wrist held between 0-15 degrees of ulnar deviation (Horowitz, 1997). Maximum grip is the average of three 3-5 second trials.

Sponsors & Collaborators

• National Institute on Aging (NIA)

  collaborator NIH

• Mayo Clinic

  lead OTHER

Principal Investigators

• K. S. Nair, M.D., Ph.D. · Mayo Clinic

Eligibility

Min Age

60 Years

Max Age

85 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-02-26

Primary Completion

2028-09-01

Completion

2028-10-01

Countries

• United States

Study Locations