Nicotine exacerbates exertional heat strain in trained men: A randomized, placebo-controlled, double-blind study, 2024, Nicole E. Moyen

Abstract
To determine if using nicotine exacerbates exertional heat strain through an increased metabolic heat production (Hprod) or decreased skin blood flow (SkBF), ten nicotine-naïve trained males (37±12 y; VO2peak: 66±10 ml·min-1·kg-1) completed four trials at 20°C and 30°C following overnight transdermal nicotine (7mg·24h-1) and placebo use in a crossover, double-blind design.

They cycled for 60 min (55% VO2peak) followed by a time-trial (~75% VO2peak) during which measures of gastro-intestinal (Tgi) and mean weighted skin ( sk) temperatures, SkBF, Hprod, and mean arterial pressure (MAP) were made.

The difference in ∆Tgi between nicotine and placebo trials was greater during 30°C (0.4±0.5°C) than 20°C (0.1±0.7°C), with sk higher during nicotine than placebo trials (0.5±0.5°C, p=0.02). SkBF became progressively lower during nicotine than placebo trials (p=0.01) and progressively higher during 30°C than 20°C trials (p<0.01); MAP increased from baseline (p<0.01) and remained elevated in all trials. The difference in Hprod between 30°C and 20°C trials was lower during nicotine than placebo (p=0.01) and became progressively higher during 30°C than 20°C trials with exercise duration (p=0.03). Mean power output during the time-trial was lower during 30°C than 20°C trials (24±25 W, p=0.02), and although no effect of nicotine was observed (p>0.59) two participants (20%) were unable to complete their 30°C nicotine trials as one reached the ethical limit for Tgi (40.0°C) whilst the other withdrew due to "nausea and chills" (Tgi=39.7°C).

These results demonstrate that nicotine use increases thermal strain and risk of exertional heat exhaustion by reducing SkBF.

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I found this study interesting considering they're doing nicotine clinical trials for LC, ME/CFS and fibro?

Not sure if the nicotine heat combo is going to enhance anything.

Exercise Enhancer?
Nicotine has even received some study as an exercise enhancer. While noting that more study was needed, a 2017 meta-analysis reported that about 2/3rds of studies found that nicotine significantly increased heart rate compared to placebo or control. Given the chronotropic incompetence that appears to be happening in ME/CFS, the ability to raise the heart rate during exercise might be a help. Increased blood pressure and blood flows were also reported to be significantly increased in multiple studies. Another 2017 study found that nicotine improved anaerobic performance but a recent study did not.

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Yes I've heard of some LC and ME/CFS talking about nicotine, didn't realise there was an official trial.

I'm not sure there is comparability between giving people who've never touched nicotine before and have a healthy body for how long? a day? a week?

it's the cliche of most people who do a first cigarette in their life 'get a headrush' vs if it really was something to be used as treatment, looking at someone eg a few months at least down the line when their body is more accustomed.


I'm struggling to see what the point of this was without that detail. If it was in people who were longer term taking it then maybe there is someone trying to make a point about 'smoking' or longer term use. But are people who are going to live in hot environments - which I guess is where this is talking about - wouldn't think of 'doing a random one-off nicotine patch' and as soon as they do that more often then the research becomes irrelevant to that because of its design?

It seems about as without purpose as finding a load of tee-totallers and having them do a one-off drinking sesh and taking said measurements. Then comparing how they coped when they weren't trying to do said sesh and thinking some minor differences are a surprise?

I also note that whilst they've got their p scores, I don't know enough to know whether the differences themselves which look pretty minescule are actually significant in the sense they'd affect someone's health or wellbeing. I am open to someone more expert saying no 0.4 in Tgi at 30C would be the make or break/feel like x?

There is one later on where the + or - error is bigger than the difference:

 

Are they looking to repurpose a deadly toxin for profit.

 

I wouldn't worry about exertional heat exhaustion from nicotine use for ME/CFS: they are not going to cycle 60 min or TT. It would be enough of a miracle if any pharmaceutical intervention restores daily functioning.

Nicotine patch was an exceptionally strong and long lasting stimulant for me the first couple of times. Then my body got used to it so quickly and it stopped working no matter how long I paused. Conversely, I didn't suffer any withdrawal either. Then again, I was at 3.5mg only. I stopped using it since it wasn't going to be a long term solution even if it worked. I suspect any pharmaceutical treatment for ME/CFS will suffer similar short coming.

 

The equivalent of walking 20 minutes in 30C for me could be the same exertion as a 60 min bike ride for a normal person.

Personally, I don't do well on stimulants. It's false energy and causes crashes because I kind of lose my sense of baseline for a short period w/o realizing.