Normally, as l warm up, l do 3 or 4 100 meter strides working down to 16 or 15 seconds, but the last few workouts l was hitting 17 and my legs felt heavy. On the last 2 sessions l felt tired. I have done some really hard workouts to get in shape. Is this something to take note of? Should l cut the long run out this week and just run easy till my next session Monday morning? I have had a solid training block, but the last few sessions l felt heavy legged.