Amanda Johnson

Correlation of isokinetic and novel hand-held dynamometry measures of knee flexion and extension strength testing.

OBJECTIVES Describe inter-rater reliability of, and correlations between a novel method of isometric knee extension and flexion and eccentric knee flexion strength using hand-held dynamometry and isokinetic testing for flexion/extension in the knees of athletic participants. Document strength data normalized to the individuals limb muscle mass. DESIGN Observational and reliability study. METHODS Inter-rater reliability for each of the hand-held dynamometry measures was established in both legs of 10 volunteers (6 male). During routine annual screening, 216 male professional football (soccer) players were examined using these same measures in addition to performing an isokinetic evaluation of knee flexion and extension strength. Intra-class correlation coefficients for inter-rater reliability, Pearson r correlations between hand-held dynamometry and isokinetic dynamometry were calculated. Peak torque, peak torque normalized to: body weight; lean body mass; and lean limb mass were documented. RESULTS Excellent inter-rater reliability was demonstrated with intra-class correlation₂,₁ values of 0.90, 0.91, and 0.96, for the eccentric hamstrings, isometric hamstrings, and isometric quadriceps measures respectively. Medium to high correlations (r=0.322-0.617) which were all significant (p<0.001) were found for the comparisons between the hand-held dynamometry and isokinetic measures. CONCLUSIONS We present 3 novel and reliable methods of examining knee flexion and extension strength using hand-held dynamometry which require less skill and strength on the part of the examiner than previous measures. Correlations between these measures and isokinetic dynamometry are documented. The hand-held dynamometry examinations took less than 4 min per player to conduct and may be useful in clinical practice where isokinetic examination can be difficult to implement.

Doppler ultrasound and tibial tuberosity maturation status predicts pain in adolescent male athletes with Osgood-Schlatter's disease: a case series with comparison group and clinical interpretation

Background The pathogenesis of the Osgood-Schlatters disease (OSD) is still debated. The fragmentation of the ossification centre has been questioned as a definitive sign of OSD and has been seen as a normal development of the anterior tibial tubercle (ATT). Objectives It is unknown if such changes are present in the presumed pathological tendon insertion seen in OSD, nor the relation of Doppler-positive changes to pain on clinical examination. Methods A prospective analysis was carried out on 20 consecutive symptomatic male athletes (13.9 years±1.3) and a comparison group of asymptomatic subjects. All underwent a comparative clinical assessment and ultrasound with colour Doppler scan on both knees. Subjective pain was recorded with a visual analogue scale (VAS) during provocative manoeuvres: palpation, resisted contraction and single leg squat. Results Positive Doppler US (within the distal end of the patellar tendon) was associated with higher pain on palpation (47±24.5 vs 18±11.4, p<0.01) and resisted static contraction (59±20.2 vs 27±12.5, p<0.001) compared with Doppler-negative subjects. No Doppler activity was found in the comparison group. VAS for palpation and resisted contraction of the athletes graded as stage 2 (51.1±22.0 and 60.0±21.2) were significantly higher than stage 3 (17.8±12.0 and 18.9±16.9) and stage 4 (15.0±7.1 and 25.0±7.1; p<0.01). Conclusions More painful OSD is associated with the presence of neo-vessels. This may be linked with a particular stage of ATT maturation and applied compressive forces. A Doppler ultrasound scan adds practical information to develop the care plan of the patient.

Skeletal maturation status is more strongly associated with academy selection than birth quarter

ABSTRACT Introduction: Selection of younger athletes for advanced training in elite sport is assumed to be based on identification of innate talent. Previous researchers have identified relative age effects to influence these selection processes; however, maturation status and skeletal age effects, which have the potential to be a greater influence, have not been widely examined. Methods: Skeletal age (categorising athletes as: early maturing, on time, or late maturing via wrist and hand X-ray and Fels classification) and birth quarter are documented for 472 boys from Elite Youth football academies and compared to reference normative data to assess their effect on academy selection. Results: It is seen that maturation status has a much stronger influence – approximately 10-fold – on selection with a systematic over-representation of early maturing athletes in elite football academies, an effect that increases with age. Conclusions: Our results demonstrate that athletes are being chosen in large by their maturation status, and as this relative benefit will have disappeared once all athletes are skeletally mature, this process is inadvertently excluding the majority of potential candidate athletes from this selection process. We suggest that consideration of maturation status of candidate athletes will result in a more equitable exposure to advanced training and the resultant performance benefits this incur.

Compelling overuse injury incidence in youth multisport athletes

Abstract The present investigation was carried out to examine the incidence and pattern of injuries in adolescent multisport athletes from youth sports academy. Injury data were prospectively collected from 166 athletes during the seasons from 2009 to 2014. A total of 643 injuries were identified, 559 (87.0%) were time-loss injuries. The overall injury incidence was 5.5 (95% confidence interval CI: 5.1–6.0), the incidence of time-loss injuries was 4.8 (95% CI: 4.4–5.2), the incidence of growth conditions was 1.2 (95% CI: 1.0–1.4) and incidence of serious injuries was 0.6 (95% CI: 0.5–0.8) per 1000 h of exposure. The prevalence of overuse injuries was 50.3%. Growth conditions represented 20.0%. Most of the injuries (67.0%) involved the lower extremities, and both foot and ankle were the most predominant injured body parts (22.0%). Knee injuries were mostly from overuse (50 vs. 23, p = .02), whereas foot and ankle injuries resulted from an acute mechanism (94 vs. 31, p < .0001). Minor and moderate injuries accounted for 87.0%. Muscle, tendon and osteochondrosis injuries accounted for 52.0% of all injuries. Comparing groups, squash sport was having the highest injury incidence (8.5 injuries per athlete). Higher exposure was associated with greater overuse relative risk (RR = 1.03, 95% CI: 1.01–1.014, p < .001). In conclusion, the results of this study identified a high incidence of injuries in this youth sports population. Striking was the prevalence of overuse injuries of 50%, which suggests the need for injury prevention protocols for adolescent highly trained athletes.

Development of a data-based interval kicking program for preparation and rehabilitation purposes in professional football

ABSTRACT Study Design: Cross-sectional Observational Cohort Study. Level of Evidence: 3. Objectives: Document kicking loads of professional soccer players in match play, and describe differences in velocity-based and distance-based classification. Describe a kicking programme suitable for physical preparation or return to play. Background: To determine reasonable kicking loads (volume and intensity) to plan for preparation and rehabilitation, normal match loads of kicking need to be described. It is not known if the kicking demands vary by playing position. Methods: Match analysis data for the entire 2012 season of the US Major League Soccer was examined using both a distance-based and velocity-based approach. Number and types of kicks were described for each playing position using both approaches. Results: Distance and velocity-based approaches were not seen to be equivalent, and a velocity-based approach was seen to be more reflective of the true kicking demands. The number and type of kicks made in each of the categories were seen to vary by playing position. On average, per game, goalkeepers made the fewest “slow” (0–6 m · s–1) kicks with 24.3 (9.1), left midfielders the most with 68.0 (32.2). Goalkeepers made the fewest “medium” (6–12 m · s–1) kicks with 9.1 (4.1) and central midfielders made the most with 36.8 (15.3). Attackers made the fewest “fast” (>12 m · s–1) kicks with 16.9 (10.1) while the left and right backs made the most with 30.8 (9.8). Conclusion: Kicking load varies by position and is best described using a velocity-based approach. These data can to inform physical preparation for kicking loads.

EPIDEMIOLOGY OF SPORTS INJURIES AMONG HIGHLY TRAINED YOUTH MULTISPORT ATHLETES

Background Injury epidemiology is imperative for the development of prevention strategies. Apart from football, little is known about injury characteristics on young elite athletes. Objective The aim of the present study is to examine the incidence of injuries sustained by adolescent highly trained multisport athletes. Design Longitudinal prospective study. Setting Aspire Academy for sport. Patients (or Participants) 166 male adolescent athletes (mean age 15.1+/−1.85) enrolled in the academy for both school and training. Interventions (or Assessment of Risk Factors) Using an injury surveillance system and record of training exposure (hours) during 5 consecutive seasons according to injury, body part, severity and mechanism. An injury was recorded as physical complaint requiring the attention of the medical staff. Overuse injuries were defined as injuries resulting from repetition of micro-trauma and with insidious onset. The severity of an injury was based on time loss (TL) criterias (Timpka et al. 2014). Main Outcome Measurements The incidence of overall injuries (per 1000 training Hours), injuries with TL, and no time loss (NTL), growth and overuse injuries were computed. Results Altogether 643 injuries were documented. Of these injuries, 87% were TL injuries with an incidence of 4.8 per 1000 hours; (95% confidence interval [CI], 4.4–5.2). Overuse injuries represented 50.3%. The prevalence of growth related injuries accounted for 20%. Exposure to training was associated with an increase of overuse injuruies (relative risk [1.03]). The most commonly diagnosed type of injury was muscle and tendon injuries (30.1%). Most injuries were located at the lower extremities (67%), with the majority affecting the foot and ankle (22%). There were only 13% serious injuries. Conclusions This study revealed high rates of overuse injuries and growth related conditions. Most injuries were minor. Our findings were consistent with similar studies on youth soccer. Further investigation is required to define injury potential risk factors.