"David's life is going to be hell in America," Marsh told the Mail on Sunday as Beckham prepares to leave Real Madrid for LA.
"He won't know what's hit him. Every other week, you have to make a road trip for away games. That does not mean a 200-mile trip up the motorway in England or Spain. It requires travelling 4,000 miles to play the New England Revolution, and there tends to be a second away game on the road.
"Over a four-day period, you can fly almost 9,000 miles and play twice. Do that four or five times, factoring in time changes, training and media engagements, and it becomes very wearing.
"Other aspects he won't understand until he gets here is the fact that the referees are next to useless and offer little protection from young men who will be looking to make a name for themselves at David's expense."