The Effects of Caffeine on Human Spinal Motoneurons

This study evaluates the effects of orally ingested, commercially available, coffee (3 mg/kg of caffeine) on the excitability of human spinal motoneurons of the lower leg.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Dietary supplement: Coffee; Dietary supplement: Decaffeinated coffee

Detailed Description

Recently, it has been shown that human spinal motoneurons do not simply act as a binary control system. Instead, they are regulated by intrinsic properties that can elicit lingering effects on the descending motoneuron. Caffeine, one of the world's most popular over-the-counter supplements, can potentially augment these characteristics of motoneurons. Using decomposition software and non-invasive, high-density surface electromyography, it is possible to extract the characteristics of these motoneurons. This project will utilize a double-blind, inactive-placebo controlled, crossover design study to examine and quantify the effects of caffeine on motoneuron excitability.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19122
      • Temple University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

● Between 18 and 70 years of age

Exclusion Criteria:

• Significant neurological or orthopedic injuries, which may limit volitional torque generation in the tested muscles.
• Significant change in the subjects' health or treatment in the past month.
• Known history of cardiovascular pathology (to include: uncontrolled hypertension, cardiac arrhythmias) or medical restrictions to caffeine ingestion.
• Allergies or dislike of coffee.
• Women who are pregnant will be excluded due to potential forces at trunk from pelvic safety harness and due to potential adverse effects of caffeine on the developing child.
• Women who are breastfeeding will be excluded due potential adverse effects on the breastfeeding infant from caffeine administration.
• Adults unable to consent, minors, pregnant women, and prisoners will not be included.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Caffeine; Single-dose, orally ingested, instant coffee.	Dietary supplement: Coffee; Starbucks brand "Via" instant coffee. (Caffeine Content: 3 mg / kg)
Placebo Comparator: Inactive Placebo; Single-dose, orally ingested, instant decaffeinated coffee (equal weight to intervention dose).	Dietary supplement: Decaffeinated coffee; Starbucks brand "Via" instant decaffeinated coffee. (Caffeine Content: 15 - 25 mg)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Motoneuron excitability (Delta-f)	Changes in motorneuron excitability, as quantified by Delta-F values. A paired motor unit technique will be utilized (Gorassini et al., 2002). (Typically, these values range from -5 to +10).	Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Motor Unit Discharge Rate	Changes in motor unit discharge rate. This is a single value that ranges from, approximately, 0 to 30.	Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention
Coherence	Changes in coherence values. Coherence provides a normalized value of the strength of correlation in the frequency domain. The magnitude of the correlation of the Fourier transforms of two spike trains is squared producing a value between 0 and 1, with 1 corresponding to a perfect linear prediction at a particular frequency (Rosenberg et al., 1989). This will be calculated using the composite spike train (Negro & Farina, 2012) and, finally, z-transformed to allow for between-trial comparisons.	Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention
Motor Unit Recruitment Threshold	Changes in motor unit recruitment threshold. As assessed by determining the amount of force (percentage of maximum volitional force output) needed to recruit an individual motor unit.	Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention

Collaborators and Investigators

• Sponsor: Temple University
• Investigators: Principal Investigator: Christopher Thompson, PT, PhD, Temple University

Publications and helpful links

General Publications

• Gorassini M, Yang JF, Siu M, Bennett DJ. Intrinsic activation of human motoneurons: possible contribution to motor unit excitation. J Neurophysiol. 2002 Apr;87(4):1850-8. doi: 10.1152/jn.00024.2001.
• Rosenberg JR, Amjad AM, Breeze P, Brillinger DR, Halliday DM. The Fourier approach to the identification of functional coupling between neuronal spike trains. Prog Biophys Mol Biol. 1989;53(1):1-31. doi: 10.1016/0079-6107(89)90004-7. No abstract available.
• Farina D, Negro F. Accessing the neural drive to muscle and translation to neurorehabilitation technologies. IEEE Rev Biomed Eng. 2012;5:3-14. doi: 10.1109/RBME.2012.2183586.

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2021
• Primary Completion (Actual): March 28, 2022
• Study Completion (Actual): March 28, 2022

Study Registration Dates

• First Submitted: May 11, 2021
• First Submitted That Met QC Criteria: May 11, 2021
• First Posted (Actual): May 18, 2021

Study Record Updates

• Last Update Posted (Actual): April 8, 2022
• Last Update Submitted That Met QC Criteria: April 7, 2022
• Last Verified: April 1, 2022

More Information

Terms related to this study

• Keywords: Caffeine; Excitability; Motor Neuron
• Other Study ID Numbers: 26014

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No