Healthy
Conditions
Keywords
Motor Neuron, Excitability, Caffeine
Brief summary
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.
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.
Interventions
DIETARY_SUPPLEMENTCoffee
Starbucks brand Via instant coffee. (Caffeine Content: 3 mg / kg)
DIETARY_SUPPLEMENTDecaffeinated coffee
Starbucks brand Via instant decaffeinated coffee. (Caffeine Content: 15 - 25 mg)
Sponsors
Temple University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Motoneuron excitability (Delta-f) | Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Motor Unit Discharge Rate | Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention | Changes in motor unit discharge rate. This is a single value that ranges from, approximately, 0 to 30. |
| Coherence | Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention | 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. |
| Motor Unit Recruitment Threshold | Measured repeatedly at set intervals; Pre-Intervention & 30, 60, 90 minutes post-Intervention | 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. |
Countries
United States
Outcome results
None listed