Dopamine and Muscle Function in the Heat

Sponsor

Brock University (Other)

Overall Status

Active, not recruiting

CT.gov ID

NCT03515668

Collaborator

(none)

Enrollment

Location

Arms

44.4

Anticipated Duration (Months)

0.1

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

our goal is to study the effects of dopamine activity, using Ritalin ingestion, on neuromuscular function over the course of a progressive heating and cooling protocol developed in our lab. We hypothesize that Ritalin will minimize the previously reported progressive impairment in neuromuscular function with hyperthermia compared to placebo, suggesting that dopamine activity preserves neuromuscular capacity with hyperthermia.

Condition or Disease	Intervention/Treatment	Phase
Muscle Force Hyperthermia	Drug: Ritalin 20 mg Tablet Drug: Placebo Oral Tablet	N/A

Detailed Description

Increased core temperature (hyperthermia) has been associated with impaired neuromuscular performance, with the majority of research suggesting that the observed fatigue is related to the central nervous system. Small doses of Ritalin has been used to study how changes in dopamine activity affects exercise capacity in the heat. This study found that 20 mg of Ritalin had no effect on exercise capacity in a thermoneutral environment of 18°C. However, when in a hot (30°C) environment, the Ritalin resulted in a 16% improvement in finishing time compared to the placebo trial. Interestingly, the higher output during the Ritalin-hot condition also resulted in higher rates of heat production and a higher (~0.6°C) core temperature, suggesting that dopamine enabled greater voluntary tolerance of hyperthermia. This matches recent work from our own work showing that motivational skills training increased both exercise tolerance and final core temperature, and it is possible that dopamine activity played a role in this improvement.

Ultimately, fatigue is shown in an inability to sustain muscular force. However, the role of dopamine activity on neuromuscular function (e.g., central activation and recruitment of muscle) during hyperthermia is unknown. One study reported that 20 mg of Ritalin did not alter neuromuscular function, but this study was done without thermal stress.

Therefore, our goal is to study the effects of dopamine activity, using Ritalin ingestion, on neuromuscular function over the course of a progressive heating and cooling protocol developed in our lab. We hypothesize that Ritalin will minimize the previously reported progressive impairment in neuromuscular function with hyperthermia (5, 7) compared to placebo, suggesting that dopamine activity preserves neuromuscular capacity with hyperthermia.

Study Design

Study Type:

Interventional

Actual Enrollment :

6 participants

Allocation:

Randomized

Intervention Model:

Single Group Assignment

Intervention Model Description:

Healthy males 18-30 years of ageHealthy males 18-30 years of age

Masking:

Single (Investigator)

Masking Description:

Double-blinding of participant and investigator, with independent investigator in charge of placebo and drug.

Primary Purpose:

Basic Science

Official Title:

The Influence of Dopamine Activity on Neuromuscular Function During Passive Heat Stress

Actual Study Start Date :

Apr 20, 2018

Anticipated Primary Completion Date :

Dec 31, 2021

Anticipated Study Completion Date :

Dec 31, 2021

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Ritalin 20 mg Ritalin, 90 min before testing	Drug: Ritalin 20 mg Tablet Single dose for all participants
Placebo Comparator: Control Identical size/taste placebo pill, 90 min before testing	Drug: Placebo Oral Tablet Placebo with same appearance/taste

Arm

Intervention/Treatment

Experimental: Ritalin

20 mg Ritalin, 90 min before testing

Drug: Ritalin 20 mg Tablet

Single dose for all participants

Placebo Comparator: Control

Identical size/taste placebo pill, 90 min before testing

Drug: Placebo Oral Tablet

Placebo with same appearance/taste

Outcome Measures

Primary Outcome Measures

Wrist flexion torque [2-4 hours after ingestion]
Maximal voluntary contraction of wrist flexion

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years to 30 Years

Sexes Eligible for Study:

Male

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

High aerobic fitness (>55 mL/kg/min maximal aerobic capacity)

Exclusion Criteria:

diagnosed cardiovascular, respiratory and/or neuromuscular disease, prescription of Ritalin or any drugs for hyperactivity within the past 1 year, any current prescription medication (except for asthma/allergy inhalers), any contraindications to Ritalin.

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Brock University	St Catharines	Ontario	Canada	L2S 3A1

Sponsors and Collaborators

Brock University

Investigators

None specified.

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

Responsible Party:

Stephen Cheung, Professor, Brock University

ClinicalTrials.gov Identifier:

NCT03515668

Other Study ID Numbers:

17-123

First Posted:

May 3, 2018

Last Update Posted:

Feb 10, 2021

Last Verified:

Feb 1, 2021

Individual Participant Data (IPD) Sharing Statement:

Plan to Share IPD:

Studies a U.S. FDA-regulated Drug Product:

Studies a U.S. FDA-regulated Device Product:

Product Manufactured in and Exported from the U.S.:

Additional relevant MeSH terms:

Hyperthermia

Methylphenidate

Study Results

No Results Posted as of Feb 10, 2021