Not sure about for running, but I was on Toprol and having a lot of dizziness and fatigue. I changed EP's and the new one put me on Atenolol, saying he believed i would have fewer symptoms because it does not pass the blood-brain barrier. It wouldn't hurt to ask. Good luck with this.
Forgot to mention the Atenolol worked better for me -- not so tired or dizzy.
JUst want to throw something out there for you to consider. My cardiologist stated that "messing" with various anti-arrhythmics, and experimenting with dosages carries as much risk as an electrophysiology study which could cure you so you wouldn't need the drugs. I competed for meany years with SVT while totally unmedicated. I did so mostly because there wasn't much available at the time to try for control of SVT. The upside of this was I didn't have any drug in me to slow me down. The downside was it left me wide open to SVT episodes. That said, once I got on an anti-arrhythmic, in this case 100mg./day of Metoprolol, it did literally nothing to prevent episodes. I still had my 3 to 5 episodes per month. Metoprolol did aid in converting them, but it didn't prevent them from happening. When I tried another drug, Sotalol, I had a very bad cardiac reaction to it, and immediately stopped it. Ablation was the cure for me, and I'm happy and thankful that my cardiologist gently guided me in that direction.
I had a bad experience with Rythmol (suppressed the sinus node too much and went off of it after a week) and tho I am now back on Norpace for the time being, if it fails I will not try any more anti-arrythmic drugs. My next stop will be an ablation if (when) my afib comes back.