Does Lions hangover give France a Six Nations advantage?

France are ruling the roost in the northern hemisphere – a familiar scenario in rugby union’s professional era.

Since the sport went open in 1995, Les Bleus have won 10 titles in the championship that expanded from being a Five Nations to a Six Nations with the addition of Italy in 2000.

Six of those victories have followed British and Irish Lions tours in the previous summer, where the best players from England, Ireland, Scotland and Wales are involved in a long-haul, high-pressure tour of one of the southern hemisphere superpowers.

Does the physical and emotional strain of a Lions tour help France in their pursuit of Six Nations glory?

Sam Warburton, who captained the Lions in 2013 and 2017 and won two Six Nations titles with Wales, believes so.

“I don’t think it is a coincidence,” he told BBC Sport’s Rugby Special of the trend.

Warburton says touring with the Lions takes as much of a toll on the mind as it does on the body.

“It’s hard to keep emotionally peaking week in, week out,” he said.

“But on a Lions tour, it feels like you’re doing that for two years straight, or 18 months straight, with very little break in between.

“I think we can all see the home nations – they have weekends where they haven’t emotionally peaked and France seem to do that more.

England wing Tommy Freeman and Ireland prop Tadhg Furlong both said similar after being involved in last summer’s Lions tour of Australia.

“Without realising it, I think I was tired,” Freeman said of his return to club side Northampton.

“My body felt like I was OK to go and I was saying to coaches ‘Yeah I’m fine, I’m fine’. I just think mentally it was a bit more of a struggle.”

Three-time Lion Furlong said: “Everything maybe seems insignificant the year after.”

France’s players may not have that much sympathy. A campaign in their domestic top flight – the Top 14 – can stretch to 29 matches.

The equivalent figure for the English Prem and the United Rugby Championship is 20 and 21 matches respectively.

However, unlike with the Home Nations, France usually rest their top stars for their summer tours.

While the Lions were touring Australia, across the Tasman Sea a France side took on New Zealand in a three-Test series without the likes of Louis Bielle-Biarrey, Matthieu Jalibert or Charles Ollivon.

Despite objections from their Kiwi hosts, concerned about the impact on ticket sales, France stuck to their policy as a second-string side suffered a 3-0 series defeat.

Ireland are adept at managing their stars’ overall workloads. For instance, Leinster and Ireland hooker Dan Sheehan has made only three starts for his province so far this season.

But Warburton believes that not all games are equal. In his opinion, the Test stages demands more of players.

“I think there’s something about playing international rugby – there’s only so many times I think you can play an international game of that magnitude, emotionally, in a year,” he said.

“The Lions tour obviously eats into that quota and I think it’s a massive part of it.”

The Six Nations’ regular calendar cycle might also play a part. In even-numbered years – in which every post-Lions Six Nations take place – France have three home games, rather than two.

Their home matches include meetings with Ireland and England, often title rivals.