No worries about last week Ellie. Still early in the plan that long term it won’t have too much effect. Going forward the plan does revert to just 1 week run and either Monday or Tuesday for efforts, with Horntye on Wednesday as your third run. I’ve had back problems my whole life because of my poor posture and more recently working at a desk for so many hours but I generally find 10-15 mins of daily stretching keeps my problems at bay.