One noticeable effect since I was diagnosed in 2015 is that I build up lactic acid much more easily when exercising. My recovery is also much poorer. Are there any studies that might offer some guidance on what to do? Should I exercise close to my threshold pace?

According to an Italian research study from 2018, it appears – just as you describe – that people with Parkinson’s experience higher levels of lactic acid in their muscles and take longer to recover. The researchers showed that a training programme on a treadmill four times a week for four weeks improved lactic acid levels, muscular endurance and balance. I would imagine that many types of exercise at a reasonable intensity are beneficial, but I wouldn’t venture to give any specific exercise advice – please do discuss this with a physiotherapist! /Dag Nyholm