Mar232025March 23, 2025April 16, 2025by Masters TTRacer

High Heart Rates Explained: AFib

Posted in Training Reports

FOUNDATION 4.3 TRAINING REPORT (03/17 – 03/23)

HIGHLIGHTS: On Thursday afternoon, I visited my local Urgent Care clinic to see if they could explain my recent string of extraordinarily high heart rates during workouts. After looking at my workout slides, they directed me to a nearby Emergency Room for testing. The initial test was a 12-Lead EKG that confirmed that I was suffering from Atrial Fibrillation (AFib). AFib is a common type of arrhythmia, which is an irregular and often rapid heartbeat. The upper chambers of the heart (atria) quiver or fibrillate instead of beating regularly, leading to blood clots, stroke, and heart failure.

I was admitted overnight to the hospital for additional tests on Friday morning. The first test was a Transthoracic Echo (TTE) that mapped my heart structure in great detail. The test report was five pages long. There was no sign of any heart damage. All 53 blood tests – Lipid Panel, TSH with Free T4 Reflex, Sedimentation Rate, Troponini, Comprehensive Metabolic Panel, CBC with Differential – were normal. The final test was in three parts. First, I underwent the first of two Myocardial Perfusion Imagings with SPECT/CT and Wall Motion. Next, I had a Lexiscan (chemical) stress test which confirmed the AFib. Finally, I underwent a second Myocardial Perfusion Imaging. The results of this final test detected a “moderate-sized area of moderately-reduced uptake in the basal inferoseptum, basal inferior and basal inferolateral segments…The remaining myocardial segments show normal uptake. No evidence of myocardial ischemia, infarction, or scar.”

Why has this happened? AFib can be caused by a variety of factors, including underlying heart conditions, high blood pressure, obesity, sleep apnea, thyroid problems, excessive alcohol consumption, and/or a family history of heart problems. Turns out that my father had a blocked artery in his early 60’s. (He survived to age 96). My brother (age 68) recently had a stent placed in his heart for a blocked artery.

Many cases of AFib are undiagnosed because the individuals never experience any symptoms, such as heart palpitations, shortness of breath, fatigue, dizziness, or lightheadedness, before they suffer a stroke or heart attack. What was amazing is that I can pinpoint precisely the date and time for the onset of my AFib. It was my workout on Saturday, March 15, from 11:15 AM to 12:40 PM, when my maximum heart rate rose to an abnormal high of 130 bpm. The previous day, my maximum workout heart rate was 83 bpm.

I will have suffered from untreated AFib for exactly one week due to the “early warning” provided by my training data collection, especially my heart rate trace during my workouts. Treatment for my AFib is two drugs, a blood thinner that reduces blood clotting and a beta-blocker to reduce the risk of high blood pressure. Otherwise, I am cleared to continue training and competing.

This is the halfway point of the season. At 26 weeks, my total mileage logged is 2,766.39. I’m on track for roughly 5,533 miles for the year, almost exactly my total mileage for last season. My lifetime yearly average mileage is 6,013 miles.

All indoor cycling sessions were completed with my recumbent trike on a Kinetic by Kurt Road Machine smart trainer + Rouvy application. I completed neither of two strength workouts this week.

DETAILS:

  • Monday’s Recovery-Endurance Blend workout was 15.02 miles in 1:04:02. Average speed was 14.1 mph; maximum speed was 15.9 mph. Average power was 75 watts; maximum power was 120 watts. The 45-minute strength routine, a mix of strength machines and bands, was cancelled.
  • Tuesday’s Recovery-Endurance Blend workout was 10.48 miles in 0:46:01. Average speed was 13.7 mph; maximum speed was 15.2 mph. Average power was 69 watts; maximum power was 101 watts.
  • Wednesday’s Foundation Miles Intervals (4 x 10/5 minutes) workout was 19.06 miles in 1:25:01. Average speed was 13.5 mph; maximum speed was 15.8 mph. Average power was 66 watts; maximum power was 114 watts.
  • Thursday’s Foundation Miles Intervals (4 x 10/5 minutes) workout was 19.06 miles in 1:25:15. Average speed was 13.4 mph; maximum speed was 15.8 mph. Average power was 66 watts; maximum power was 112 watts. The 45-minute strength routine, a mix of strength machines, free weights, and rope exercises, was cancelled. Spent the night in the hospital awaiting tests for AFib.
  • Friday’s workout was rescheduled. Spent the day in the hospital undergoing tests for AFib.
  • Saturday’s Fast Pedals (3 x 4/1 minutes) workout was 14.02 miles in 1:00:02. Average speed was 14.0 mph; maximum speed was 15.7 mph. Average power was 74 watts; maximum power was 107 watts.
  • Saturday’s Sweet Spot Tempo Intervals (3 x 10/5 minutes) workout was 15.82 miles in 1:04:22. Average speed was 14.7 mph; maximum speed was 16.8 mph. Average power was 85 watts; maximum power was 128 watts.
  • Sunday’s Foundation Miles (4 x 15/5 minutes) workout was 23.15 miles in 1:39:03. Average speed was 14.0 mph; maximum speed was 15.8 mph. Average power was 73 watts; maximum power was 117 watts.

BY THE NUMBERS:

  • Total Distance: 116.61 mi
  • Longest Ride: 23.15 mi
  • Total Time for Week: 8:23:36 (h:m:s)
  • Avg Speed: 13.9 mph
  • Max Speed: 16.8 mph
  • Avg Power: 73 watts
  • Max Power: 128 watts
  • Calories: 2,085 C
  • Avg Weight: 177.0
  • Chronic Training Load: 51 (-1)