I’m a big believer in distance, golden rule number 1, but also understand this can lead to injury or a general feeling of fatigue. If, when, this happens it’s time to take some time out and either do some other cardio based , low impact exercise ( cycling, rowing, swimming) or complete rest. My friend Gareth once said ‘running is something I do between injuries’. Unfortunately so many runners can never achieve their goals or reach their full potential because of injuries caused by distance.
Recognize the signs and take action otherwise golden rule number 3 will be broken, don’t get injured. Signs may include restlessness, sleepless nights or interrupted sleep and generally not feeling that great. Your runs will feel laboured and you’ll certainly notice a drop in performance and a rise in your average heart rate.
As for distance being the key to performance I am very much in the Matt Fitzgerald camp of 80% easy pace and 20% speed work; but with a good dose of distance. Compare this to the experts at FIRST who are very much “less is more” advocating three pace sessions and two cardio a week. In the end it’s what works for you. If you are susceptible to injury with high distance go for quality over quantity.