NCT03515668

Dopamine and Muscle Function in the Heat

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

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 6 (actual)
• Sponsor: Brock University · Academic / Other
• Sex: Male
• Age: 18 Years – 30 Years
• Healthy volunteers: Accepted

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.

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.

Conditions

• Muscle Force
• Hyperthermia

Interventions

Type	Name	Description
DRUG	Ritalin 20 mg Tablet	Single dose for all participants
DRUG	Placebo Oral Tablet	Placebo with same appearance/taste

Timeline

• Start date: 2018-04-20
• Primary completion: 2021-12-31
• Completion: 2021-12-31
• First posted: 2018-05-03
• Last updated: 2021-02-10

Locations

1 site across 1 country: Canada