The Portumna native earned a well-deserved first senior cap against Canada last week. Ireland got out of the blocks slowly but put together some good combinations in the second half to pull away.
Muldoon said: "I think we always expected Canada to come out and be very strong. They are a very physical, very strong side in that respect and were very aggressive for the first 20 to 25 minutes.
"I think with the time period that we had together, we struggled especially in the first half to get some patterns together and to get a strong foothold in the game.
"But once we knuckled down in the second half things began to come together and hopefully with that attitude this weekend we can do the same."
Muldoon played in the back row alongside the hugely-experienced Denis Leamy and his Munster colleague Niall Ronan, whom Muldoon knew from their days in the Ireland Youths set-up.
"I enjoyed playing in the back row combination with Denis and Niall. I've known Niall for a good few years as we played Irish Under-18 Youths together a long time ago - I think in 2000 was the last time - and I've played against Denis a lot the whole way up.
"It was a good experience and the second half was a lot better and as we got a bit more continuity, we got to hold onto the ball a whole lot more so it meant we could get involved in the game more.
"The whole first half was very scrappy and there were a lot of breakdowns and unforced errors, so I'm sure for the people who were watching at home it was not that pretty, but hopefully we can improve against the USA."
Muldoon, Connacht's Senior Player of the Year, will remain on in America with a number fo the squad and management ahead of Ireland 'A' participating in the Churchill Cup in Colorado.
"Looking at the USA this weekend they're another big, strong physical team. I think rugby in the USA is really starting to grow with a lot more numbers playing and they're getting better and better as every year goes by.
"Of course with Eddie O'Sullivan there as their coach, they will be well prepared and he will know a lot of the Irish players so I'm sure his team will be well briefed on us.
"I'm delighted to get selected again and we are expecting a good hard-fought game.
"The heat will no doubt be a big factor and although it's the same for both of the teams, I suppose we are not as used to the conditions so it will be a tough game for everybody involved.
"I think work-rate will be really important just as it was last week and in the second half when we upped it a bit as the combinations got used to each other, things began to flow a bit better for us.
"With another week's training, people know each other a little bit better and hopefully that will help us through.
"Come Sunday it's a Test match arena so we are all looking forward to it and obviously everybody will be giving 100% to try and hold onto that jersey."