Osteoarthritis: hip injuries in footballers

Osteoarthritis: hip injuries in footballers

Hip injuries in footballers - osteoarthritis of the hip

The researchers sent a questionnaire designed to assess the prevalence of osteoarthritis (OA) of various joints to the managers of the 92 league and premiership football clubs in England and Wales. Of the 74 who responded to the survey, 68 were ex-professional footballers. The self-reported prevalence of OA of the hip in those managers was then compared with radiographic evidence of OA of the hip in 136 ‘controls’ matched for age and sex.

Of the 68 ex-players, nine (13.24%) reported having OA of the hip, and six of these had undergone eight total hip replacements. Of the 136 controls, only two (1.47%) showed radiographic evidence of OA and none had undergone hip replacements.

The most surprising aspect of these findings was that none of the ex-players with OA of the hip reported having any hip injuries during their playing careers. ‘This’, say the researchers, ‘is in contrast with OA of the knee, which is associated with previous knee surgery or injury.’

Why the difference? The researchers speculate that some apparent groin injuries sustained by footballers are actually repetitive minor hip joint injuries rather than soft tissue injuries.

The prevalence of OA of the hip among ex-professional footballers in this study confirms the findings of a previous study, but the comparison with non-footballers is a new development. The researchers recognise that their study has limitations – mainly the lack of scientific rigour in comparing self-reported OA with radiographically-identified disease.

However, the findings are significant enough to point to the need for further studies comparing radiographic evidence in both groups – and, according to the researchers, such a study is already under way.

Br J Sports Med 2003;37:80-81

Isabel Walker

Head injury: research suggests footballers are not at risk of brain damage

Footballers are not in danger of experiencing brain damage

That’s the encouraging conclusion of a major US study comparing ‘neurocognitive’ function in three groups of students at the University of North Carolina, comprising:

• 
  91 male and female foootballers, with an average of 15 seasons of prior participation in the sport;
  
• 
  96 athletes, other than footballers including players of women’s field hockey, women’s lacrosse and men’s baseball;
  
• 
  53 non-athlete ‘controls’.
  

The researchers were testing the theory that extended exposure to football may be associated with chronic impairment of brain function, as put forward by some recent European studies. ‘A unique aspect of the game,’ they point out, ‘is the purposeful use of the unprotected head for controlling and advancing the ball. Reports of studies of high-level amateur and professional European footballers suggest that extended exposure to the game may be associated with chronic cognitive impairment.

‘It is further postulated’, they add, ‘that multiple subconcussive impacts to the head, such as those involved in repeated heading of the ball, may be responsible for degenerative impairment of normal brain function. Some authors have even suggested that repeated heading of the ball in game or practice situations may be comparable in effect to receiving multiple blows to the head in a boxing match or while sparring.’Such reports have apparently sent ‘shock waves’ through US youth football communities, with mandatory use of protective headgear proposed as a possible solution. Happily, though, these fears seem unfounded – at least as far as college-age athletes are concerned. For a battery of ‘neuropsychological’ tests, measuring such capacities as orientation, concentration, problem-solving, verbal association, attention and memory failed to reveal any significant differences between the groups.Even a history of concussion did not appear to predispose to mental impairment, since subjects with a history of two or more concussions were no more likely to have depressed neurocognitive performance that those with no such history. When analysis was performed by sex, the only significant difference found on any of the tests was for the verbal learning test of immediate memory recall. But this was as significant for the controls as for the footballers.The researchers conclude: ‘Our results indicate that participation in football is safe, at least up to the collegiate level, when considering its effect on neurocognitive function. Neither participation in football nor concussion history was associated with impaired performance of neurocognitive function in high-level collegiate football players with a mean age of 19 years. Although our findings need to be replicated in other settings, these results should provide reassurance that exposure to football during youth and adolescence does not appear to be associated with measurable deficits.’

However, it is clear that football players are at particular risk of concussion, and the researchers suggest that the focus should now be placed on ways to reduce the risk, most especially through ‘quality instruction’.

…But the Risk Appears to Increase with Age

That’s the rather less sanguine conclusion of another American study, which found that footballers performed worse than swimmers on measures of conceptual thinking, with older football players scoring particularly poorly on reaction time and concentration, as well as conceptual thinking.

The researchers, from Florida University and the State University of New York, compared performance in four neuropsychological tests (assessing motor speed, attention, concentration, reaction time and conceptual thinking) in 32 footballers and 29 swimmers. Of the footballers, 26 were college students and six current or former professionals, with a median age of 41.5; of the swimmers, 29 were students and seven veterans (median age 42.68).

The researchers were testing two hypotheses:

• 
  that footballers, particularly older ones, would show poorer neuropsychological test performance than swimmers, who are less likely to sustain sport-related brain injury;
  
• 
  that the severity of neuropsychological deficits in footballers would correlate with the extent of their participation in the sport – ie the length of their careers and their level of competition.
  

‘To our knowledge,’ state the researchers, ‘this is the first study to demonstrate a dose-response relationship whereby greater football experience is linked to poorer NP (neuropsychological) test performance, consistent with the hypothesis that playing football places individuals at risk for NP compromise.’

The fact that this dose-response relationship was even stronger when goalkeepers, who rarely head the ball, were excluded from the analysis supports the idea that the deficits detected are caused by football-related head trauma.

The researchers hasten to point out, though, that there is no clear evidence that such impairments, as demonstrated on formal testing, lead to practical difficulties in daily living.

They conclude: ‘The younger groups’ performance leads us to concur with the assertion that, in the absence of frank concussion, younger footballers are unlikely to manifest significant NP impairment. However, the potential eventual consequences of long-continued football participation must be appreciated.’

They suggest that the risks could be minimised by such precautions as using proper size balls, coaching of correct heading technique, availability of adequate on-site care, return-to-play guidelines and annual NP screenings for athletes in head-contact sports.

Am J Sports Med 2002 Mar-Apr 30(2), pp157-162 J Sports Med Phys Fitness 2002 Mar 42(1), pp103-107

Fitness for football

Fitness For Football: Endurance training boosts performance in the field

Football players need a combination of technical, tactical and physical skills in order to succeed. It is odd, therefore, that football research has tended to focus on technique and tactics, with little emphasis on how to develop the endurance and speed needed to become a better player.

Some studies have also shown that footballers tend to cover less distance and work at lower intensities during the second half of games than during the first half. The logical interpretation of these findings is that fatigue is limiting the players and that if they were fitter they would perform more effectively in the latter stages of their matches. None the less, until now no investigation has clearly shown that improving aerobic capacity and overall fitness boosts performance on the football field.

Fortunately, that deficiency has now been remedied, thanks to the work of Jan Helgerud and his colleagues at the Norwegian University of Science and Technology in Trondheim(3). Their new study involved 19 male players from two Norwegian junior lite teams - 'Nardo' and 'Strindheim' - all of whom had been playing football for at least eight years. Both teams had been among the most successful in Norway over the past five years and six of the participants were members of the Norwegian national junior team. The players had an average age of 18 and mean mass of 72kg (158lb).

Aerobic interval training v extra technical training

At the beginning and end of the eight-week study period, all players were tested for VO2max, lactate threshold, vertical jumping height, 40m sprint ability, maximal kicking velocity and the technical ability to kick a football through defined targets.

After eight weeks of twice-weekly interval training, the players in the training group had improved VO2max by almost 11%, from 58.1 to 64.3 ml.kg-1.min-1; meanwhile control group players had not upgraded VO2max at all! Similarly, lactate-threshold running speed improved by 21% and running economy by 6.7% in the training group, while controls again failed to improve at all. Clearly the players in the training group were gaining tremendous physiological benefits from just two aerobic workouts per week!

Happily, all of these physiological details translated into some markedly improved performances on the football field: interval-trained athletes increased the total distance covered during games by 20% (from 8,619 to 10,335m) and also doubled the number of times they sprinted during games (a sprint being defined as an all-out run lasting at least two seconds). Furthermore, after eight weeks of interval training the number of involvements with the ball per game increased by 24%, from 47 to 59. (Involvements were defined as situations in which a player was either in physical contact with the ball or applying direct pressure to an opponent in possession of the ball.)

Owen Anderson

References

Science and Football, T Reilly, A Lees, K Davids, and WJ Murphy (Eds). London: E & F N Spon, 1988, pp 95-107

2. Proceedings of the 1st International Congress on Sports Medicine Applied to Football, Rome, 1980, L Vecchiet (Ed) Rome: D Guanillo, 1980, pp 795-801

3. Medicine and Science in Sports and Exercise, vol 33(11), pp 1925-1931, 2001

4. Running Research News, vol 12-3, pp 11-12, 1996

Football training: how to take a penalty kick

How to win the penalty shoot-out mind game

The classic mind game of soccer penalty-taking begins when the referee points to the spot. Anticipation, strong nerve, cool head, firm resolve - all these factors come into play in a brief but highly intense drama. Will the keeper second-guess the striker? Will the kick - as happens surprisingly frequently - fly high over the goal?

Science has now come to the aid of goalies with research which may help them to stay calm. It seems that in the split second before the striker hits the ball, the orientation of his or her hips indicates which way the ball will fly. The results were presented at the second Asian Congress on Science and Football in Kuala Lumpur, Malaysia.

Mark Williams, head of science and football at Liverpool John Moores University, explained: 'If the taker's hips are square-on to the goalkeeper in a right-footed kicker, the penalty tends to go the right-hand side of the keeper. If his hips are more 'open', the kick tends to go the left.'

His study investigated saving strategies by showing goalkeepers life-sized video footage of strikers before and during penalties. He stopped the film four times: 120 milliseconds before the kick; 40 milliseconds before; at the point of impact; and 40 milliseconds afterwards. Each time, he asked the keepers to predict the outcome.

Semi-professionals were consistently better than unskilled amateurs at guessing which of four target spots in the goal the ball would hit. At 120 milliseconds before impact, half the semi-pros guessed correctly. The success rate rose to 62 per cent 40 milliseconds before, and 82 per cent at impact. At each stage, the amateurs lagged ten percentage points behind the semi-pros.

Williams reported that other visual cues include angle of the striker's run-up and the orientation of the non-kicking foot. Ian Franks and Todd Harvey at the University of British Columbia identified this latter factor as the crucial cue in a study of 138 penalties in World Cup competitions between 1982 and 1994. The non-kicking foot pointed to where the ball would go 80 per cent of the time.

The question is, will this information make things harder for strikers, or will it introduce a new dimension to the mind game as strikers try even harder to disguise their intentions?

Although soccer is the most popular sport in the world, with over 120 million amateur players worldwide, scientific research concerning the nutritional needs of soccer players has been scant. Fortunately, new investigations are being conducted, and the up-to-date research suggests that soccer players should eat and drink like marathon runners!