Peaking Long Run

This morning was the peaking session for my marathon training.
It was a 10k warm-up + 3x7km @MP
Everything quite well, I felt good legs all the way, but I struggled in the last interval because of the wind coming from the sea
- 1st interval: 3'46"/km average HR avg 161, felt very easy (even too much ... was the wind ?)
- 2nd interval: 3'51"/km, HR average 167the wind was gaining strength and in some section I had to push the throttle
- 3rd: 3'52"/km . HR average 168. I was obviously getting tired, but still manage to respect both the pace and keep the HR inside the 170bpm. My biggest issue was strong pain in the feet.
I was probably running "heavy" and my NB lightweight trainers are abandoning me ... So I felt every foot landing very painful.
total 35km/22Miles .

What I envy most to the Pro runners is that after a tough run, they take a long bath, massage and a nap. My recovery was a quick shower, making breakfast in 30 seconds, and having my daughter wanting to be carried around on my shoulders and running all around the estate ... her leg speed would rival Veronica Campbell ...

total for the week: 109km(68Miles) run and 870km(550Miles) driving the car ...

today's issue: do you also make long runs with intervals or other kind of variations in pace ? or still prefer the long steady pace run ?
Personally, in a modern marathon training, we can not avoid simulating more closely the specific of marathon also in training. For a runner on 70/90 Miles/week, a steady run of 20M can be like "too" easy and not very stimulating. The real challenge of the marathon is keeping the pace also after the 20Miles with depleted reserves and muscular fatigue and this need specific conditioning.