Showing papers in "British Journal of Sports Medicine in 2004"

Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players

Abstract: Background: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly. Objective: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players. Methods: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0–30 m and 10 m shuttle run sprint) and vertical jumping height. Result: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height. Conclusions: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance.

The Football Association Medical Research Programme: an audit of injuries in professional football—analysis of hamstring injuries

Abstract: Objective: To conduct a detailed analysis of hamstring injuries sustained in English professional football over two competitive seasons. Methods: Club medical staff at 91 professional football clubs annotated player injuries over two seasons. A specific injury audit questionnaire was used together with a weekly form that documented each clubs' current injury status. Results: Completed injury records for the two competitive seasons were obtained from 87% and 76% of the participating clubs respectively. Hamstring strains accounted for 12% of the total injuries over the two seasons with nearly half (53%) involving the biceps femoris. An average of five hamstring strains per club per season was observed. A total of 13 116 days and 2029 matches were missed because of hamstring strains, giving an average of 90 days and 15 matches missed per club per season. In 57% of cases, the injury occurred during running. Hamstring strains were most often observed during matches (62%) with an increase at the end of each half (p<0.01). Groups of players sustaining higher than expected rates of hamstring injury were Premiership (p<0.01) and outfield players (p<0.01), players of black ethnic origin (p<0.05), and players in the older age groups (p<0.01). Only 5% of hamstring strains underwent some form of diagnostic investigation. The reinjury rate for hamstring injury was 12%. Conclusion: Hamstring strains are common in football. In trying to reduce the number of initial and recurrent hamstring strains in football, prevention of initial injury is paramount. If injury does occur, the importance of differential diagnosis followed by the management of all causes of posterior thigh pain is emphasised. Clinical reasoning with treatment based on best available evidence is recommended.

High prevalence of osteoarthritis 14 years after an anterior cruciate ligament tear in male soccer players: a study of radiographic and patient relevant outcomes

Abstract: Objective: To identify the consequences of an anterior cruciate ligament (ACL) tear in a cohort of male soccer players 14 years after the initial injury with respect to radiographic knee osteoarthritis and patient relevant outcomes. Methods: Of 219 male soccer players with an …

Evidence for complex system integration and dynamic neural regulation of skeletal muscle recruitment during exercise in humans

Abstract: A model is proposed in which the development of physical exhaustion is a relative rather than an absolute event and the sensation of fatigue is the sensory representation of the underlying neural integrative processes. Furthermore, activity is controlled as part of a pacing strategy involving active neural calculations in a "governor" region of the brain, which integrates internal sensory signals and information from the environment to produce a homoeostatically acceptable exercise intensity. The end point of the exercise bout is the controlling variable. This is an example of a complex, non-linear, dynamic system in which physiological systems interact to regulate activity before, during, and after the exercise bout.

Eccentric training in patients with chronic Achilles tendinosis: normalised tendon structure and decreased thickness at follow up

Abstract: Eccentric training in patients with chronic Achilles tendinosis: normalised tendon structure and decreased thickness at follow up

A one season prospective cohort study of volleyball injuries

Abstract: Objective: To estimate the overall incidence of acute and overuse volleyball injuries, and to describe factors associated with ankle sprains. Methods: 486 players from the second and third Dutch national volleyball divisions participated in the study and were followed prospectively during a whole season. Three measurements were made during the season (baseline, follow up 1, and follow up 2), where all players completed a questionnaire on demographic variables (only at baseline), sports participation, use of preventive measures, and previous injuries. Volleyball exposure during training and matches was recorded for each individual player by the coach on a weekly exposure form. In case of injury the coach provided the injured player with an injury registration form, which had to be completed within one week after the onset of injury. Results: 100 injuries were reported, resulting in an overall injury incidence of 2.6 injuries/1000 hours. The incidence of acute injuries was 2.0/1000 hours. Ankle sprains (n = 41) accounted for most of the acute injuries, and 31 (75%) of all players with an ankle sprain reported a previous ankle sprain. Twenty five overuse injuries were reported. The overall incidence of overuse injuries was 0.6/1000 hours; the back and the shoulder were the most common sites. Conclusions: Ankle sprain is the most common injury in volleyball, accounting for 41% of all volleyball related injuries. Previous injury seems to be an important risk factor for an ankle sprain. Injury prevention programmes should focus on ankle sprains and concentrate on players with previous ankle sprains.

Relation between running injury and static lower limb alignment in recreational runners

Abstract: Objectives: To determine if measurements of static lower limb alignment are related to lower limb injury in recreational runners. Methods: Static lower limb alignment was prospectively measured in 87 recreational runners. They were observed for the following six months for any running related musculoskeletal injuries of the lower limb. Injuries were defined according to six types: R1, R2, and R3 injuries caused a reduction in running mileage for one day, two to seven days, or more than seven days respectively; S1, S2, and S3 injuries caused stoppage of running for one day, two to seven days, or more than seven days respectively. Results: At least one lower limb injury was suffered by 79% of the runners during the observation period. When the data for all runners were pooled, 95% confidence intervals calculated for the differences in the measurements of lower limb alignment between the injured and non-injured runners suggested that there were no differences. However, when only runners diagnosed with patellofemoral pain syndrome (n = 6) were compared with non-injured runners, differences were found in right ankle dorsiflexion (0.3 to 6.1), right knee genu varum (−0.9 to −0.3), and left forefoot varus (−0.5 to −0.4). Conclusions: In recreational runners, there is no evidence that static biomechanical alignment measurements of the lower limbs are related to lower limb injury except patellofemoral pain syndrome. However, the effect of static lower limb alignment may be injury specific.

Endocannabinoids and exercise

Abstract: Exercise induces changes in mental status, particularly analgesia, sedation, anxiolysis, and a sense of wellbeing. The mechanisms underlying these changes remain unknown. Recent findings show that exercise increases serum concentrations of endocannabinoids, suggesting a possible explanation for a number of these changes. This article provides an overview of this emerging field.

The Football Association medical research programme: an audit of injuries in academy youth football

Abstract: Objectives: To undertake a prospective epidemiological study of the injuries sustained in English youth academy football over two competitive seasons. Methods: Player injuries were annotated by medical staff at 38 English football club youth academies. A specific injury audit questionnaire was used together with a weekly return form that documented each club’s current injury status. Results: A total of 3805 injuries were reported over two complete seasons (June to May) with an average injury rate of 0.40 per player per season. The mean (SD) number of days absent for each injury was 21.9 (33.63), with an average of 2.31 (3.66) games missed per injury. The total amount of time absent through injury equated to about 6% of the player’s development time. Players in the higher age groups (17–19 years) were more likely to receive an injury than those in the younger age groups (9–16 years). Injury incidence varied throughout the season, with training injuries peaking in January (p Conclusions: Footballers are at high risk of injury and there is a need to investigate ways of reducing this risk. Injury incidence at academy level is approximately half that of the professional game. Academy players probably have much less exposure to injury than their full time counterparts. Areas that warrant further attention include the link between musculoskeletal development and the onset of youth related conditions such as Sever’s disease and Osgood-Schlatter’s disease, the significant number of non-contact injuries that occur in academy football, and the increased rates of injury during preseason training and after the mid season break. This study has highlighted the nature and severity of injuries that occur at academy level, and the third part of the audit process now needs to be undertaken: the implementation of strategies to reduce the number of injuries encountered at this level.

Why we should allow performance enhancing drugs in sport

Abstract: The legalisation of drugs in sport may be fairer and safer In 490 BC, the Persian Army landed on the plain of Marathon, 25 miles from Athens. The Athenians sent a messenger named Feidipides to Sparta to ask for help. He ran the 150 miles in two days. The Spartans were late. The Athenians attacked and, although outnumbered five to one, were victorious. Feidipides was sent to run back to Athens to report victory. On arrival, he screamed “We won” and dropped dead from exhaustion. The marathon was run in the first modern Olympics in 1896, and in many ways the athletic ideal of modern athletes is inspired by the myth of the marathon. Their ideal is superhuman performance, at any cost. The use of performance enhancing drugs in the modern Olympics is on record as early as the games of the third Olympiad, when Thomas Hicks won the marathon after receiving an injection of strychnine in the middle of the race.1 The first official ban on “stimulating substances” by a sporting organisation was introduced by the International Amateur Athletic Federation in 1928.2 Using drugs to cheat in sport is not new, but it is becoming more effective. In 1976, the East German swimming team won 11 out of 13 Olympic events, and later sued the government for giving them anabolic steroids.3 Yet despite the health risks, and despite the regulating bodies’ attempts to eliminate drugs from sport, the use of illegal substances is widely known to be rife. It hardly raises an eyebrow now when some famous athlete fails a dope test. In 1992, Vicky Rabinowicz interviewed small groups of athletes. She found that Olympic athletes, in general, believed that most successful athletes were using banned substances.4 Much of the writing on the use of …

From catastrophe to complexity: a novel model of integrative central neural regulation of effort and fatigue during exercise in humans

Abstract: It is a popular belief that exercise performance is limited by metabolic changes in the exercising muscles, so called peripheral fatigue. Exercise terminates when there is a catastrophic failure of homoeostasis in the exercising muscles. A revolutionary theory is presented that proposes that exercise performance is regulated by the central nervous system specifically to ensure that catastrophic physiological failure does not occur during normal exercise in humans.

Logical limitations to the “catastrophe” models of fatigue during exercise in humans

Abstract: This paper addresses six hallmark physiological requirements that must be correct if Hill's cardiovascular/ anaerobic/catastrophic model is the exclusive explanation for the fatigue that develops during maximum exercise to exhaustion. This leads to a review of the evidence supporting other, related "catastrophe" models that have been developed to explain fatigue during exercise of lower intensities and longer durations. It is concluded that there is little published evidence supporting the theory that fatigue occurs only after physiological homeostasis fails according to the prediction of these catastrophe models. Rather, it is proposed that fatigue in any form of exercise may form part of a regulated, anticipatory response co-ordinated in the subconscious brain. The ultimate goal of this regulation is to preserve homeostasis in all physiological systems during exercise, regardless of intensity or duration or the environmental conditions in which it is undertaken.

Evaluation of isokinetic force production and associated muscle activity in the scapular rotators during a protraction-retraction movement in overhead athletes with impingement symptoms

Abstract: Objectives: To determine if the muscle force and electromyographic activity in the scapular rotators of overhead athletes with impingement symptoms showed differences between the injured and non-injured sides. Methods: Isokinetic peak force was evaluated during protraction and retraction of the shoulder girdle, with simultaneous recording of electromyographic activity of the three trapezius muscles and the serratus anterior muscle, in 19 overhead athletes with impingement symptoms. Results: Paired t tests showed significantly lower peak force during isokinetic protraction at high velocity (p<0.05), a significantly lower protraction/retraction ratio (p<0.01), and significantly lower electromyographic activity in the lower trapezius muscle during isokinetic retraction on the injured side than on the non-injured side (p<0.05). Conclusion: These results confirm that patients with impingement symptoms show abnormal muscle performance at the scapulothoracic joint.

Field and laboratory testing in young elite soccer players

Abstract: Aim: To determine if there are correlations between the physical fitness of young soccer players assessed by field and laboratory testing. Methods: Thirty four male soccer players took part in the study (mean (SD) age 17.5 (1.1) years, height 177.8 (6.7) cm, weight 70.5 (6.4) kg). Maximal oxygen uptake (VO2MAX) during treadmill running and vertical jump height on a force platform were measured in the laboratory. Field tests consisted of a soccer specific endurance test (Bangsbo test) and 30 m sprint with 10 m lap times. Results: The Bangsbo test correlated with the lowest velocity associated with VO2MAX (vVO2MAX; R2 = 0.55, p<0.001), but not with VO2MAX. Sprint times at 30 m and 20 m were related to peak extension velocity and peak extension force measured during vertical jumping, but not to vertical jump height per se. The jumping force and velocity could explain 46% of the 30 m sprint performance (R2 = 0.46, p<0.001). Conclusion: The Bangsbo test and 30 m sprint test correlate with vVO2MAX and vertical jump force and velocity respectively. The Bangsbo test does not give a good estimate of VO2MAX in young soccer players.

A pilot study of the eccentric decline squat in the management of painful chronic patellar tendinopathy

Abstract: Objectives: This non-randomised pilot study investigated the effect of eccentric quadriceps training on 17 patients (22 tendons) with painful chronic patellar tendinopathy. Methods: Two different eccentric exercise regimens were used by subjects with a long duration of pain with activity (more than six months). (a) Nine consecutive patients (10 tendons; eight men, one woman; mean age 22 years) performed eccentric exercise with the ankle joint in a standard (foot flat) position. (b) Eight patients (12 tendons; five men, three women; mean age 28 years) performed eccentric training standing on a 25° decline board, designed to increase load on the knee extensor mechanism. The eccentric training was performed twice daily, with three sets of 15 repetitions, for 12 weeks. Primary outcome measures were (a) 100 mm visual analogue scale (VAS), where the subject recorded the amount of pain during activity, and (b) return to previous activity. Follow up was at 12 weeks, with a further limited follow up at 15 months. Results: Good clinical results were obtained in the group who trained on the decline board, with six patients (nine tendons) returning to sport and showing a significantly reduced amount of pain over the 12 week period. Mean VAS scores fell from 74.2 to 28.5 (p = 0.004). At 15 months, four patients (five tendons) reported satisfactory results (mean VAS 26.2). In the standard squat group the results were poor, with only one athlete returning to previous activity. Mean VAS scores in this group were 79.0 at baseline and 72.3 at 12 weeks (p = 0.144). Conclusion: In a small group of patients with patellar tendinopathy, eccentric squats on a decline board produced encouraging results in terms of pain reduction and return to function in the short term. Eccentric exercise using standard single leg squats in a similar sized group appeared to be a less effective form of rehabilitation in reducing pain and returning subjects to previous levels of activity.

Can we manage sport related concussion in children the same as in adults

Abstract: Evidence based guidelines are required for the management of concussive injury in children Consensus guidelines for managing sport related concussion in adults have been increasingly widely implemented.1 So far, there are no guidelines that enable clinicians to manage similar sporting concussive injuries in children. Furthermore, there are a number of important anatomical, physiological, and behavioural differences between adults and children that suggest that adult guidelines will need to be either modified or rewritten to manage injuries in this age group. The annual incidence of traumatic brain injury (TBI) in adults is remarkably constant worldwide and has been estimated at between 180 and 300 cases per 100 000 population.2–5 This is believed to be an underestimate of the true incidence as an equivalent number of mild injuries are treated by general practitioners and do not result in hospital admission.6 Direct sport participation accounts for approximately 15–20% of all such TBI3,7 and in children a further smaller percentage of TBI is associated with play activities.8 In children aged 15 years and under, the estimated incidence rate of TBI is 180 per 100 000 children per year of which approximately 85% are categorised as mild injuries.7 In the US, it has been estimated that more than 1 million children sustain a TBI annually and that TBI accounts for more than 250 000 paediatric hospital admissions as well as more than 10% of all visits to emergency service settings.9 In child and adolescent populations, few well controlled studies exist to identify the age specific frequency and outcome of sport related concussive injuries. The most common cognitive sequelae of concussive injuries in children are the same as for adults, namely reduced speed of information processing, poor attention, and impaired executive function.10–14 Concussion may also have a significant …

Effect of tai chi exercise on proprioception of ankle and knee joints in old people

Abstract: Objectives: To assess if tai chi, a traditional Chinese form of exercise, could improve proprioception in old people and if the effects of tai chi on proprioception are more evident than other exercise forms in the elderly. Methods: By detecting the threshold of passive movement, ankle and knee joint kinaesthesis was measured in 21 elderly long term tai chi practitioners (TC group), 20 elderly long term swimmers/runners (S/R group), and 27 elderly sedentary controls (control group). Results: Ankle joint kinaesthesis differed significantly among the three groups (p = 0.001). Subjects in the TC group could detect a significantly smaller amount of motion than those in the S/R group (p = 0.022) and control group (p = 0.001). No significant difference was found between the S/R group and the control group (p = 0.701). The threshold for detection of passive motion was significantly different in knee extension and flexion. For knee flexion, the TC group showed a significantly lower mean threshold for detection of passive motion than the control group (p = 0.026). There were no significant differences between the S/R group and control group (p = 0.312), or between the TC group and S/R group (p = 0.533). For knee extension, no significant difference was noted among the three groups (p = 0.597). Conclusions: The elderly people who regularly practiced tai chi not only showed better proprioception at the ankle and knee joints than sedentary controls, but also better ankle kinaesthesis than swimmers/runners. The large benefits of tai chi exercise on proprioception may result in the maintenance of balance control in older people.

Injuries in youth amateur soccer and rugby players—comparison of incidence and characteristics

Abstract: Objectives: In reviewing the literature on sports injuries, few studies could be found in which exposure related incidences of injury in different types of sport were compared. These studies indicated that ice hockey, handball, basketball, soccer, and rugby are popular team sports with a relatively high risk of injury. The aim of the study was to compare the characteristics and incidence of injuries in male youth amateur soccer and rugby players. Methods: This prospective cohort study comprised an initial baseline examination to ascertain the characteristics of the players and their level of performance, and a one season observation period during which a physician visited the team weekly and documented all occurring injuries. Twelve soccer and 10 rugby school teams with male amateur players aged 14-18 years were selected for the study. 145 soccer and 123 rugby players could be followed up over one season. Results: Comparison of the incidence of soccer and rugby injuries indicated that rugby union football was associated with a significantly higher rate of injury than soccer. The differences were pronounced for contact injuries, injuries of the head, neck, shoulder, and upper extremity, as well as for concussion, fractures, dislocations, and strains. Rugby players incurred 1.5 times more overuse and training injuries in relation to exposure time, and 2.7 times more match injuries than soccer players. Three rugby players but no soccer players had to stop their participation in sport because of severe injury. Conclusion: The incidence of injury in New Zealand school teams playing soccer or rugby union is high, probably in part because of the low ratio of hours spent in training relative to hours spent playing matches. The development and implementation of preventive interventions to reduce the rate and severity of injury is recommended.

A survey of flexibility training protocols and hamstring strains in professional football clubs in England

Abstract: Objectives: To investigate the relation between current flexibility training protocols, including stretching, and hamstring strain rates (HSRs) in English professional football clubs Method: Questionnaire based data on flexibility training methods and HSRs were collected from 30 English professional football clubs in the four divisions during the 1998/99 season Data were coded and analysed using cross tabulation, correlation, and multiple regression Results: Flexibility training protocols were characterised by wide variability, with static stretching the most popular stretching technique used Hamstring strains represented 11% of all injuries and one third of all muscle strains About 14% of hamstring strains were reinjuries HSRs were highest in the Premiership (133 (94)/1000 hours) with the lowest rates in Division 2 (78 (29)/1000 hours); values are mean (SD) Most (97%) hamstring strains were grade I and II, two thirds of which occurred late during training/matches Forwards were injured most often Use of the standard stretching protocol (SSP) was the only factor significantly related to HSR (r = 2045, p = 0031) in the correlation analysis, suggesting that the more SSP is used, the lower the HSR About 80% of HSR variability was accounted for by stretching holding time (SHT), SSP, and stretching technique (STE) in the multiple regression equation: HSR = 3779 2 (033SHT 2 1005SSP + 224STE) i 234 SHT (negatively correlated with HSR) was the single highest predictor, and accounted for 30% of HSR variability, and an additional 40% in combination with SSP Conclusions: Flexibility training protocols in the professional clubs were variable and appeared to depend on staffing expertise Hamstring stretching was the most important training factor associated with HSR The use of SSP, STE, and SHT are probably involved in a complex synergism which may reduce hamstring strains Modification of current training patterns, especially stretching protocols, may reduce HSRs in professional footballers

Effects of androgenic-anabolic steroids on apolipoproteins and lipoprotein (a)

Abstract: Objectives: To investigate the effects of two different regimens of androgenic-anabolic steroid (AAS) administration on serum lipid and lipoproteins, and recovery of these variables after drug cessation, as indicators of the risk for cardiovascular disease in healthy male strength athletes. Methods: In a non-blinded study (study 1) serum lipoproteins and lipids were assessed in 19 subjects who self administered AASs for eight or 14 weeks, and in 16 non-using volunteers. In a randomised double blind, placebo controlled design, the effects of intramuscular administration of nandrolone decanoate (200 mg/week) for eight weeks on the same variables in 16 bodybuilders were studied (study 2). Fasting serum concentrations of total cholesterol, triglycerides, HDL-cholesterol (HDL-C), HDL2-cholesterol (HDL2-C), HDL3-cholesterol (HDL3-C), apolipoprotein A1 (Apo-A1), apolipoprotein B (Apo-B), and lipoprotein (a) (Lp(a)) were determined. Results: In study 1 AAS administration led to decreases in serum concentrations of HDL-C (from 1.08 (0.30) to 0.43 (0.22) mmol/l), HDL2-C (from 0.21 (0.18) to 0.05 (0.03) mmol/l), HDL3-C (from 0.87 (0.24) to 0.40 (0.20) mmol/l, and Apo-A1 (from 1.41 (0.27) to 0.71 (0.34) g/l), whereas Apo-B increased from 0.96 (0.13) to 1.32 (0.28) g/l. Serum Lp(a) declined from 189 (315) to 32 (63) U/l. Total cholesterol and triglycerides did not change significantly. Alterations after eight and 14 weeks of AAS administration were comparable. No changes occurred in the controls. Six weeks after AAS cessation, serum HDL-C, HDL2-C, Apo-A1, Apo-B, and Lp(a) had still not returned to baseline concentrations. Administration of AAS for 14 weeks was associated with slower recovery to pretreatment concentrations than administration for eight weeks. In study 2, nandrolone decanoate did not influence serum triglycerides, total cholesterol, HDL-C, HDL2-C, HDL3-C, Apo-A1, and Apo-B concentrations after four and eight weeks of intervention, nor six weeks after withdrawal. However, Lp(a) concentrations decreased significantly from 103 (68) to 65 (44) U/l in the nandrolone decanoate group, and in the placebo group a smaller reduction from 245 (245) to 201 (194) U/l was observed. Six weeks after the intervention period, Lp(a) concentrations had returned to baseline values in both groups. Conclusions: Self administration of several AASs simultaneously for eight or 14 weeks produces comparable profound unfavourable effects on lipids and lipoproteins, leading to an increased atherogenic lipid profile, despite a beneficial effect on Lp(a) concentration. The changes persist after AAS withdrawal, and normalisation depends on the duration of the drug abuse. Eight weeks of administration of nandrolone decanoate does not affect lipid and lipoprotein concentrations, although it may selectively reduce Lp(a) concentrations. The effect of this on atherogenesis remains to be established.

A congested football calendar and the wellbeing of players: correlation between match exposure of European footballers before the World Cup 2002 and their injuries and performances during that World Cup

Abstract: Objectives: To investigate the correlation between exposure to match play for football players in European clubs during the months prior to the World Cup 2002 and the injuries and performa ...

Mechanisms of head injuries in elite football

Abstract: Objectives: The aim of this study was to describe, using video analysis, the mechanisms of head injuries and of incidents with a high risk of head injury in elite football. Methods: Videotapes and injury information were collected prospectively for 313 of the 409 matches played in the Norwegian (2000 season) and Icelandic (1999 and 2000 season) professional leagues. Video recordings of incidents where a player appeared to be hit in the head and the match was consequently interrupted by the referee were analysed and cross referenced with reports of acute time loss injuries from the team medical staff. Results: The video analysis revealed 192 incidents (18.8 per 1000 player hours). Of the 297 acute injuries reported, 17 (6%) were head injuries, which corresponds to an incidence of 1.7 per 1000 player hours (concussion incidence 0.5 per 1000 player hours). The most common playing action was a heading duel with 112 cases (58%). The body part that hit the injured player’s head was the elbow/arm/hand in 79 cases (41%), the head in 62 cases (32%), and the foot in 25 cases (13%). In 67 of the elbow/arm/hand impacts, the upper arm of the player causing the incident was at or above shoulder level, and the arm use was considered to be active in 61 incidents (77%) and intentional in 16 incidents (20%). Conclusions: This study suggests that video analysis provides detailed information about the mechanisms for head injuries in football. The most frequent injury mechanism was elbow to head contact, followed by head to head contact in heading duels. In the majority of the elbow to head incidents, the elbow was used actively at or above shoulder level, and stricter rule enforcement or even changes in the laws of the game concerning elbow use should perhaps be considered, in order to reduce the risk of head injury.

Physiology of sport rock climbing

Abstract: Rock climbing has increased in popularity as both a recreational physical activity and a competitive sport. Climbing is physiologically unique in requiring sustained and intermittent isometric forearm muscle contractions for upward propulsion. The determinants of climbing performance are not clear but may be attributed to trainable variables rather than specific anthropometric characteristics.

Postactivation potentiation: role in performance

Abstract: The role of postactivation potentiation in enhancement of strength and speed performance requires further research Postactivation potentiation (PAP), also known as activity-dependent potentiation, is an increase in muscle isometric twitch and low frequency tetanic force following a “conditioning” activity.1,2 Examples of conditioning activity are a series of evoked isometric twitches (staircase or treppe), an evoked isometric tetanic contraction (post-tetanic potentiation), a sustained isometric maximal voluntary contraction (MVC), and a series of dynamic contractions. In fact, any type of contractile activity is likely to activate the mechanism of PAP—that is, phosphorylation of myosin regulatory light chains, which increases Ca2+ sensitivity of the myofilaments.2 The result is an amplified level of myosin cross bridge activity in response to submaximal concentrations of myoplasmic Ca2+. A notable feature of PAP is that it has no effect on the force of high frequency tetanic isometric contractions, because in such contractions a “saturating” concentration of Ca2+ is attained, making any increase in Ca2+ sensitivity inconsequential. Although less studied, PAP also increases the force of shortening (concentric) contractions,3 and the highest frequency at which PAP is effective is greater for rapid shortening (concentric) contractions than for isometric contractions.4 On the basis of the foregoing, it would appear that PAP …

Weight changes, medical complications, and performance during an Ironman triathlon

Abstract: Background: Subjects exercising without fluid ingestion in desert heat terminated exercise when the total loss in body weight exceeded 7%. It is not known if athletes competing in cooler conditions with free access to fluid terminate exercise at similar levels of weight loss. Objectives: To determine any associations between percentage weight losses during a 224 km Ironman triathlon, serum sodium concentrations and rectal temperatures after the race, and prevalence of medical diagnoses. Methods: Athletes competing in the 2000 and 2001 South African Ironman triathlon were weighed on the day of registration and again immediately before and immediately after the race. Blood pressure and serum sodium concentrations were measured at registration and immediately after the race. Rectal temperatures were also measured after the race, at which time all athletes were medically examined. Athletes were assigned to one of three groups according to percentage weight loss during the race. Results: Body weight was significantly (p<0.0001) reduced after the race in all three groups. Serum sodium concentrations were significantly (p<0.001) higher in athletes with the greatest percentage weight loss. Rectal temperatures were the same in all groups, with only a weak inverse association between temperature and percentage weight loss. There were no significant differences in diagnostic indices of high weight loss or incidence of medical diagnoses between groups. Conclusions: Large changes in body weight during a triathlon were not associated with a greater prevalence of medical complications or higher rectal temperatures but were associated with higher serum sodium concentrations.

Master’s performance in the New York City Marathon 1983–1999

Abstract: Background: Physical activity in older people is believed to slow down the natural aging process through its effects on disuse atrophy. Objectives: To show that elite master (age above 50) male and female athletes, as a group, have improved their running times over the last two decades at a greater rate than their younger counterparts. Methods: Running time, age, and sex of all 415 000 runners in the New York City Marathon from 1983 to 1999 were examined using linear regression analysis. Results: The number of master participants increased at a greater rate than their younger counterparts (p Conclusions: Participation in the New York City Marathon is increasing at a higher rate in the master groups than in other age groups. Male and female masters continued to improve running times at a greater rate than the younger athletes, whose performance levels have plateaued. This is the largest study to compare master athletic performance with younger counterparts and men with women.

Reliability and validity of measures taken during the Chester step test to predict aerobic power and to prescribe aerobic exercise

Abstract: Objectives: To evaluate the reliability and validity of measures taken during the Chester step test (CST) used to predict VO2max and prescribe subsequent exercise. Methods: The CST was performed twice on separate days by 7 males and 6 females aged 22.4 (SD 4.6) years. Heart rate (HR), ratings of perceived exertion (RPE), and oxygen uptake (VO2) were measured at each stage of the CST. Results: RPE, HR, and actual VO2 were the same at each stage for both trials but each of these measures was significantly different between CST stages (p<0.0005). Intertrial bias ±95% limits of agreement (95% LoA) of HR reached acceptable limits at CST stage IV (-2±10 beats/min) and for RPE at stages III (0.2±1.4) and IV (0.5±1.9). Age estimated HRmax significantly overestimated actual HRmax of 5 beats/min (p = 0.016) and the 95% LoA showed that this error could range from an underestimation of 17 beats/min to an overestimation of 7 beats/min. Estimated versus actual VO2 at each CST stage during both trials showed errors ranging between 11% and 19%. Trial 1 underestimated actual VO2max by 2.8 ml/kg/min (p = 0.006) and trial 2 by 1.6 ml/kg/min (not significant). The intertrial agreement in predicted VO2max was relatively narrow with a bias ±95% LoA of -0.8±3.7 ml/kg/min. The RPE and %HRmax (actual) correlation improved with a second trial. At all CST stages in trial 2 RPE:%HRmax coefficients were significant with the highest correlations at CST stages III (r = 0.78) and IV (r = 0.84). Conclusion: CST VO2max prediction validity is questioned but the CST is reliable on a test-retest basis. VO2max prediction error is due more to VO2 estimation error at each CST stage compared with error in age estimated HRmax. The HR/RPE relation at >50% VO2max reliably represents the recommended intensity for developing cardiorespiratory fitness, but only when a practice trial of the CST is first performed.

Clinical examination of athletes with groin pain: an intraobserver and interobserver reliability study

Abstract: Background: Groin pain is a diagnostic and therapeutic challenge to sports medicine. The literature provides no consensus on definitions of or diagnostic criteria for groin pain in athletes. To compare the results of research and treatments, the methods used to diagnose and evaluate the degree of groin pain must be clearly defined and reproducible. Objectives: To describe clinical examination techniques for groin pain in athletes and evaluate the intraobserver and interobserver reliability of these. Methods: Eighteen athletes, nine with sports related groin pain and nine without groin pain, were examined by two doctors and two physiotherapists. The examiners were trained in the examination techniques before the study. The examiners were blinded to the symptoms and identity of the subjects. The subjects were examined twice by each examiner in random order. The examinations included evaluation of adductor muscle related pain and strength, iliopsoas muscle related pain, strength, and flexibility, abdominal muscle related pain, and strength and pain at the symphysis joint. Kappa statistics and percentage of agreement were used to evaluate the data. Results: Overall, the κ values and percentage of agreement were in accordance and showed good reliability of the examinations. The κ values for the intraobserver agreement were above 0.60 in 11 of 14 tests, and those for the interobserver agreement of the pain tests were above 0.60 in eight of 10 tests. The only test without acceptable interobserver reliability was the strength test for iliopsoas muscle. Conclusion: All but one of the tests investigated were reproducible and subject only to limited intraobserver and interobserver variation.

Reductions in pre-season training loads reduce training injury rates in rugby league players

Abstract: Objectives: To investigate if reductions in pre-season training loads reduced the incidence of training injuries in rugby league players, and to determine if the reductions in training loads compromised the improvements in physical fitness obtained during the pre-season preparation period. Methods: A total of 220 sub-elite rugby league players participated in this 3 year prospective study. Players underwent measurements of speed, muscular power, and maximal aerobic power before and after three 4 month (December to March) pre-season preparation periods (2001–2003). A periodised skills and conditioning program was implemented, with training loads progressively increased in the general preparatory phase of the season (December to February) and reduced slightly in March in preparation for the competitive phase of the season. Training loads were calculated by multiplying the training session intensity by the duration of the training session. Following the initial season (2001), training loads were reduced through reductions in training duration (2002) and training intensity (2003). The incidence of injury was prospectively recorded over the three pre-season periods. Results: The training loads for the 2002 and 2003 pre-season periods were significantly lower (p Conclusions: These findings demonstrate that reductions in pre-season training loads reduce training injury rates in rugby league players and result in greater improvements in maximal aerobic power.

What do we mean by the term “inflammation”? A contemporary basic science update for sports medicine

Abstract: Most practicing sports medicine clinicians refer to the concept of "inflammation" many times a day when diagnosing and treating acute and overuse injuries. What is meant by this term? Is it a "good" or a "bad" process? The major advances in the understanding of inflammation in recent years are summarised, and some clinical implications of the contemporary model of inflammation are highlighted.