On Sunday Michel Vorm's late, untimely error at White Hart Lane cast Tottenham out of the FA Cup at the hands of Leicester City. It was the 37th time they'd walked out onto a pitch this season and it seems as though they're starting to feel the pace as they battle on three fronts for trophies and qualification for Europe's elite club competition, the Champions League.
By comparison, Leicester were featuring in their 25th game of the season. Manchester United have also played 25, while Chelsea are their closest rivals having played 34 fixtures this season.
Another way of looking at the mountain that Spurs must climb this season is this; rivals Arsenal, who once more are blocking their north London's rivals path to the top four, have played four fixtures in January. Tottenham have their ninth later today.
That is the lot of a team that traipses across the continent to European backwaters to take part in the Europa League, and also enjoys a domestic cup run. Indeed perhaps it was a small blessing for boss Mauricio Pochettino when Vorm fumbled the ball into his own net from Jeffrey Schlupp's seemingly innocuous shot.
Of course, much has been made of the affect of travel on Tottenham's form and fitness, having been in the Europa League for the past four seasons. In their last two campaigns Spurs have played 20 times in the Champions League's runt of a little brother. Of the 20 games that have followed their European exertions they have won just eight times, losing 10 and drawing two. It seems that sort of form has left them on an unenviable treadmill of cause and effect.
Tottenham's problems of fatigue are not unique though. Indeed the Premier League has long battled a wider problem compared to their European rivals by not having a winter break - and that problem is exacerbate by the World Cup over the summer.
English football's top flight contributed 105 players to festival of football in South America - the most of all of Europe's top leagues - and although Arsenal boss Arsene Wenger was shrewd enough to give his World Cup winners games off at the start of the campaign plenty were forced to go into the hard slog of a hard season and a congested winter period.
The World Cup in Brazil presented its own unique challenges too; there were vast distances for players to travel and intense heat; England, for example, played in scorching sun in the Amazonian city of Manaus and travelled more than 4,000 miles to fly to their group games - and that figure doesn't include the flight from the UK. One small grace is that the most recent World Cup saw a relatively low number of injuries-per-match, down from 2.7-per-match in the 2002 edition.
Struggle for life
Manchester United boss Louis van Gaal was seemingly less-than-impressed with his first experience of the Premier League's festive period after watching his side "struggle for life" in their 0-0 draw against Tottenham two days after beating Newcastle on Boxing Day.
"It's scientifically proven that the body cannot recover within 48 hours," he told reporters. "When, as an FA, you allow [teams] to play matches, you see what it's like. The second half was much different to the first half and not only for Manchester United -- also for Tottenham Hotspur."
The biggest problem facing Premier League managers - and one they will be very much aware of going into the second half of the season when the trophies are handed out - is managing a phenomenon called cumulative fatigue.
After lobbying from the Professional Footballer's Association all clubs agreed to give players five weeks off in a 12 month period. However they tend to do that in the summer between seasons - when the big tournaments are played and the area remains something of a grey one. Spain for example played the European Championship, the Confederation Cup and then the World Cup in consecutive summers between long, hard seasons.
The fact that most of their players come from either Barcelona or Real Madrid - seven of eleven came from those two in their final group game this summer - means they are likely to play more games because of their involvement in the cup competitions - perhaps sheds some light on their early exit from the tournament in Brazil. For example, Sergio Ramos has played an incredible 164 games over the last three full seasons on two separate continents.
Clubs of course keep an eagle on the exertions of their star players across the season, while individual recovery processes such as ice baths are implemented. Many use heart-rate and GPS trackers monitors during training sessions games to measure exertion and workload. Arsene Wenger's favourite phrase for those who are in danger of risking injury because of being overworked is "entering the red zone".
In the "Red Zone"
"Unfortunately you never know how far you can push it," Wenger said in December when talking about star winger Alexis Sanchez's risk of burnout. "We are not scientific enough to predict that completely but he has good recovery potential. He recovers very quickly.”
The research that has been done in the area of cumulative fatigue certainly backs up the claim that tiredness not only lessens the performance of football players but heightens their chance of injury.
A study of 27,000 matches by former Wales assistant coach Raymond Verheijen in 2012 found that teams playing every three days "offers emphatic proof that teams playing every
three days are substantially disadvantaged by player fatigue."
Verheijen says that his findings show that two-day recovery for players can be dangerous, and also warned against the risk posed to players on their way back from injury. "A top-fit player recovers from the game after 48 hours," he said last year. "But a player who is not top fit takes 72 hours to recover. So a less fit player is more susceptible to injury."
Talking about Theo Walcott's ACL injury that ended his season last time round, the Dutch coach said: "Nine out of 10 ACLs can be avoided, because the main reason why an ACL happens is that the knee is temporarily unprotected when the players turns or leans"
"Normally, your muscles contract to stabilise the knee and nothing happens. Over the holiday period when players play so many games and have accumulated fatigue, their nervous system slows down and the signal from the brain to the muscles gets slower.
"When they make explosive movements the signal arrives a millisecond too late, the player leans or turns with an unprotected knee and the ACL snaps. You often see the ACL happens with a very simple action – something a player has done in his career one million times. On one million occasions the knee was protected and everything was in its place. On the one-million-and-first time the signal arrives too late and the ACL snaps."
Interestingly, a study last year found that "fluid ingestion during 90 min of soccer-type exercise" was unable to offset the reduction muscle power in the knee and legs. So if players are participating in back-to-back games on a regular basis the increased risk of dehydration leads to the greater risk of fatigued muscles which in turn means an increased likelihood of more injuries. Mental fatigue, a factor which is often overlooked, also plays a part.
For Tottenham their regular participation in the Europa League led to a shift in approach from the powers that be when Andre Villas-Boas joined the club back in 2013. The Portuguese boss went about signing enough players to have two of equal standard covering each position - and current incumbent Pochettino is reaping the rewards of that. He made nine changes for the defeat against Leicester and will certainly rotate against Sheffield United tonight as they look to make the Capital One Cup final.
He's used 25 different players in the Premier League so far this season - a far cry from the days of Harry Redknapp - and much has been made of his intense fitness regime designed to keep Spurs going for longer.
Indeed, the north London club had one of the best records over the festive period; in a 22-day spell between December and January the played seven matches, roughly one every three days, and didn't lose once. Spurs have made a habit of snatching late wins and Jan Vertonghen said 'the character and fitness of the team is showing' after they did just that against Sunderland recently.
However, no matter how sophisticated the plans and recovery systems in pace to avoid fatigue the human body is limited in what it can do; something Spurs have found out to their cost, and there's a fear that they may fade as they lunge for the line. That's happened twice in recent seasons and they've let slip big advantages over Arsenal to miss out on the top four, and while part of that could be a mental block there's no doubt that fitness played a part.
"I think that [I am] not happy with the performance, the draw is fair," Pochettino said after their 0-0 draw against Crystal Palace in December, just before the going was starting to get tough. The team didn't show the freshness, maybe because we played in nine days four games or in six days three games."
The Argentinian has the pressure of trying to deliver Champions League football back to White Hart Lane while balancing his squad for the deluge of games they're facing. Along with Tottenham's remaining Premier League games, if they make it to the final of both the Capital One Cup and the Europa League they would have an incredible 74 games come May. Manchester United - if they make it to the final of the FA Cup without replays, will have played 56.
Whichever way you carve that up, it's a massive disadvantage for Pochettino and Spurs, as they try and to shatter the glass ceiling they repeatedly bang their heads against in the middle of every May.
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