Ah, varying heart rates based on training volume, an intriguing topic! While I'm not a medical professional, I can share some insights from my cycling experiences.
An elevated heart rate of 60 bpm, given you don't feel overtrained, could be due to several factors. Changes in sleep patterns, stress, hydration, or even caffeine intake can influence your heart rate.
However, in the context of training volume, it's worth noting that increases in heart rate during periods of high training load are quite common. This is often referred to as the "parasympathetic withdrawal" phenomenon, where your body takes longer to recover and return to its resting state after intense workouts.
Conversely, a decrease in training volume can also lead to a higher resting heart rate as your body adapts to the reduced physical stress.
So, while it's possible that your elevated heart rate could be linked to your training volume, there could be other factors at play. It might be worth discussing this with a healthcare professional or a fitness coach to get a more accurate understanding. Happy cycling!