Video analysis of injuries and incidents in Norwegian professional football.

OBJECTIVES: This study describes the characteristics of injuries and high risk situations in the Norwegian professional football league during one competitive season using Football Incident Analysis (FIA), a video based method. METHODS: Videotapes and injury information were collected prospectively for 174 of 182 (96%) regular league matches during the 2000 season. Incidents where the match was interrupted due to an assumed injury were analysed using FIA to examine the characteristics of the playing situation causing the incident. Club medical staff prospectively recorded all acute injuries on a specific injury questionnaire. Each incident identified on the videotapes was cross referenced with the injury report. RESULTS: During the 174 matches, 425 incidents were recorded and 121 acute injuries were reported. Of these 121 injuries, 52 (43%) were identified on video including all head injuries, 58% of knee injuries, 56% of ankle injuries, and 29% of thigh injuries. Strikers were more susceptible to injury than other players and although most of the incidents and injuries resulted from duels, no single classic injury situation typical for football injuries or incidents could be recognised. However, in most cases the exposed player seemed to be unaware of the opponent challenging him for ball possession. CONCLUSIONS: This study shows that in spite of a thorough video analysis less than half of the injuries are identified on video. It is difficult to identify typical patterns in the playing events leading to incidents and injuries, but players seemed to be unaware of the opponent challenging them for ball possession.

Football incident analysis: a new video based method to describe injury mechanisms in professional football.

OBJECTIVES: To develop and test a new video based method for match analysis that combines football specific and medical information to achieve a better understanding of the injury mechanisms and events leading up to high risk situations. METHODS: Football incident analysis (FIA) is a video based method describing incidents that may result in an injury using 19 variables and categories modified from match analysis. Videos from 35 of 76 (46%) official Norwegian under 21 matches played from 1994 to 1998 were analysed. Two football experts classified each incident on the basis of predetermined criteria, and their results were compared using interobserver and intraobserver reliability tests. RESULTS: kappa correlation coefficients for interobserver and intraobserver agreement were very good for 63% and 95% and good for 37% and 5% of the variables respectively. Fifty two incidents were recorded (1.6 incidents per team per match or 94 per 1000 player hours), and 16 (31%) led to injuries (0.5 injuries per match or 29 injuries per 1000 player hours). FIA results showed that 28 incidents occurred while attacking in midfield zone 2 or the attacking zone, and 24 took place while defending in the defensive zone or midfield zone 1. Midfielders were exposed in 67% of the incidents, mainly in breakdown attacks or during long attacks by the opposing team. Of the 28 incidents during offence, only one was classified as having great potential to score a goal. Most incidents (70%) were the result of tackling duels both in the offensive and defensive playing phases. Of the 21 offensive incidents resulting from tackling duels, in 19 cases the exposed player was unaware of the tackling (passive duellist). CONCLUSIONS: This study shows that football incident analysis is a potentially valuable tool for understanding the events leading up to injuries in football.

Diminished greenness of tomato leaves exposed to ozone and post-exposure recovery of greenness.

The response to ozone (O(3)) of greenness, in terms of estimated total chlorophyll concentration (Chl), of leaves at three plant canopy levels was studied in tomato (Lycopersicon esculentum Mill.) over a 10-day period following O(3) exposure. Plants of the cultivars 'New Yorker' and 'Tiny Tim' were grown at 25/15 degrees or 30/15 degrees day/night temperatures in growth chambers and exposed to 0.00, 0.08, 0.16 or 0.24 microl litre(-1) O(3) for 7 h day(-1) for four consecutive days in controlled environment exposure chambers. Measurement of Chl in the top, middle and bottom canopy leaves with a calibrated SPAD-501 leaf greenness meter indicated that the growth temperatures tested did not significantly influence the response of Chl to O(3). Ozone-induced loss of Chl was widespread in the entire foliage canopy, including foliage which did not demonstrate visible injury. In both cultvars the Chl in leaves at all three canopy levels declined as a function of increasing O(3) concentration when measured 2, 4, 6, 8 and 10 days after the exposure period. However, the slopes for leaves in the top and middle canopies decreased with increasing time after exposure. An analysis of this apparent Chl recovery indicated that leaves in the top and middle canopies exposed to 0.16 and 0.24 microl litre(-1) increased in greenness at a rapid rate after the marked initial decline associated with O(3) treatment. The apparent recovery of the top canopy may have reflected the growth of new leaves and their inclusion in the measurements, but this was not the case for the middle canopy for which the same leaves were measured throughout the post-exposure period. Bottom canopy leaves did not demonstrate significant recovery of Chl.