I'm 20 and he's 45. He's aiming to peak at the end of the summer and I'm aiming for a peak in November. We've both just been doing mileage + Strides and a decent number of tempos. We have flat areas and hills around. He's slightly slower than me (He's aiming for sub 17 5k and I should be almost a minute faster come fall, although right now I'm only about 30 seconds faster than him over 5k.)
So any workout will be slightly harder for him than it will be for me, but he needs the speed. I was thinking a structured fartlek of some kinds but I'm not sure. Anything thats faster than Tempo pace is what I'm looking for. Currently no access to a track. Thanks!