Check any meds you're taking, prescription and OTC.

Supplements too, since you also lift weights and mentioned some muscle growth. Lots of possibilities for stimulants than can affect HR and BP. Been there, done that, had persistent high resting heart rate and blood pressure spikes to show for it. One by one I identified and reduced or eliminated possible causes.

Unfortunately some health supplements aimed at athletes may bury ingredients in fine print, or omit listing them entirely with some exotic imported supplements. Ephedra, guarana, yohimbe and other stimulants are popular in many supplements advertised as energy boosters. I won't buy any supplements that lack full ingredients lists or come from sketchy sources. In some cases the unscrupulous makers add stimulants to give users an energy buzz that they'll mistake for "better nutrition" so they'll keep buying one brand of protein powder over another.

For years I used Sudafed for painful sinus congestion (pseudo-ephedrine, not phenylephrine -- the latter is useless for sinus congestion but somewhat useful in hemorrhoid ointments) and bronchial decongestants containing ephedrine for asthma. I knew those were increasing my heart rate and BP but had no alternatives since I lost coverage for Flonase and albuterol inhalers -- the latter are very expensive without insurance. But through the VA all my meds are covered now so I have those inhalers again.

However I wanted to reduce the ephedra based decongestants. A month or so ago I tried bromelain, a pineapple enzyme that reduces inflammation -- it seems to be most effective on sinus inflammation for some reason, less effective with other inflammation. And niacin, Vitamin B3, which loosens mucus congestion. There are published papers for both supplements on the NIH/NCBI PubMed site. Works for me. It's not as effective as Sudafed, but works pretty well and my HR and BP are back within normal range.

Ditto, [MENTION=78894]Carbonfiberboy[/MENTION]'s suggestion to get tested for possible immune system problems or other issues that might aggravate problems with inflammation. It's a little less likely at your age, mid 30s, but still worth checking. I ignored my health until I was 60 and was lucky to get away with it.

For over a decade I ignored a doctor's warning about Hashimoto's thyroid disorder. I was first told about it in the late 1990s or early 2000s. Got so busy with other stuff that I neglected my health for years, never saw a doctor at all for more than a decade. It all caught up with me very suddenly in 2018. Thyroid swelled so badly it was distorting and constricting my esophagus and trachea. Had zero energy, could hardly get out of bed let alone ride my bike. Chronic pain throughout the whole body. Finally had surgery in November to remove a cancerous thyroid lobe.

Still recovering but feeling better. It'll probably be months before I'm back to normal but I can still handle 2-3 rides of 20-30 miles a week at a moderate effort -- around 16 mph average, probably averaging 125-150 watts with occasional brief efforts of 200 watts for a few minutes and 300-400 for up to 30 seconds or so. That's based on crunching Strava data in to various online calculators, but those seem to match the data for folks I know who use power meters on the same rides (and we're about the same size and weight).

I don't mean to sound any alarm about immune disorders. Usually I'm skeptical about such claims (some of my friends claim to be hypersensitive to everything from gluten to "negative ions" -- as opposed to the positive kind -- to the extent they sound like candidates to become bubble-people), which is why I ignored my own symptoms for years. But occasionally it's a real thing. A simple blood test would have set me straight years ago, but I just didn't get it done.

I still take some supplements that probably aren't necessary or even helpful -- DHEA, pregnenolone -- but I'm anxious to regain my cycling form. Ditto iron since I'm borderline anemic, but none of the pill supplements seem to make any difference so I'm eating chicken livers and beef liver once or twice a week.