Under-17 Research Articles

Comparison of athletic movement between elite junior and senior Australian football players

ABSTRACTThis study compared the athletic movement skill between elite Under-18 (U18) Australian football (AF) and senior Australian Football League (AFL) players. The U18 sample (n = 13; 17.7 ± 0.6 years) were representatives of an elite talent development programme. The AFL players were classified accordingly; Group 1 (1–4 AFL seasons; n = 20; 21.2 ± 1.9 years) and Group 2 (>5 AFL seasons; n = 14; 26.3 ± 2.6 years). Participants performed an athletic movement skill assessment, inclusive of five foundational movements. Each movement was scored across three assessment points using a three-point scale. Total score for each movement (maximum of nine) and overall score (maximum of 63) were used as criteria. Multivariate analysis of variance (MANOVA) was used to test the effect of developmental group (three levels) on the criteria. Receiver operating curves were built to examine the discriminant capability of the overall score. A significant effect of developmental group was noted, with the U18 sample having a lower mean total score for four of the five movements. Overall scores of 49/63 and 50/63 discriminated the elite U18 sample from Group 1 and Group 2, respectively. U18 players may have less developed athletic movement skills when compared to their senior AFL counterparts.

Initial investigation of nutrition and supplement use, knowledge and attitudes of under-16 rugby players in South Africa

Background. Internationally young athletes are reported to have a poor understanding of the principles of sports nutrition and supplement use; hence their diet may be unhealthy and inappropriate for participation in sport. There is limited research on current nutritional knowledge and attitudes of under-16 (U16) age-group level rugby players in South Africa (SA).Objectives. To assess dietary- and supplement-related knowledge and attitudes of 198 U16 national-level rugby players in SA.Methods. Over a period of four consecutive years a total of 198 players attending nutrition workshops at the annual selection camp received and completed an anonymous structured questionnaire. Anthropometric measures (weight, height and skinfolds) were gathered by registered biokineticists.Results. Of players 87% (168/193) indicated that they wanted to increase lean muscle mass, with 42% (82/194) feeling pressurised to do so by their coach and/or parents. Almost half (85/196) believed their diets to be poor. Players had better knowledge about nutrition recovery strategies than pre-game meals. Seventy per cent (136/195) identified optimal timing and 56% (109/196) knew the ideal macronutrient composition of recovery meals. Over 60% of players believed supplements were safe (115/192) and necessary (132/193) for increasing muscle mass, and almost half (106/195) believed they could take creatine. Over a third (68/170) also believed that the protein quality of supplements was higher than that of food. Supplements were primarily recommended by coaches and non-dietetic medical practitioners. Eight of the players self-prescribed supplements and four were taking supplements on the advice of a store salesperson or representative.Conclusion. The elite U16 rugby players in this study lacked comprehensive sports nutritional knowledge, yet had an overly positive attitude toward supplementation and used supplements haphazardly to achieve body composition goals. Tailor-made nutrition interventions with a strong education component are recommended to improve players’ nutritional knowledge, as well as access to registered dietitians working in sport to advise on supplements.

Isokinetic evaluation of knee muscles in soccer players: discriminant analysis

ABSTRACT Introduction: Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance. Objectives: To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17) soccer category from the professional (PRO). Methods: Thirty four players were assessed (n=17 for each category). The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm), total work (J), average power (W), angle of peak torque (deg.), agonist/ antagonist ratio (%), measured for three velocities (60°/s, 120°/s and 300°/s), with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories. Results: The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work. Conclusion: Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players.

The cricket bowling performance of different racial groups at a junior provincial level in South Africa

Objective. To investigate the difference in performance and bowling opportunity of black African (BA), coloured/Indian (C/I) and white (W) cricket bowlers at a junior provincial level in South Africa between 2006 and 2012. Methods. Data of all players performing in the South African interprovincial under-13 (U13), under-15 (U15) and under-19 (U19) tournaments were analysed. Bowling performance (bowling average and the top 20 wicket takers relative to their par representation) and bowling opportunity (number of overs bowled) were compared between racial groups. Results. There were no significant differences in the bowling averages between BA bowlers and the other racial groups between 2008 and 2012. BA bowling averages were only significantly worse than W bowlers in the U13s in 2006 and U19s in 2007. BA bowling averages were also only significantly worse than C/I in the U13s and U15s in 2007. BA bowlers were below par representation in the top 20 wicket takers in each year for the U15s and U19s and below par representation for the U13s in 2007 - 2009 and 2011. The performance of C/I and W bowlers was relatively similar across the age groups. BA players bowled significantly fewer overs than W bowlers in the U13s in 2006, in the U15s in 2007 and 2009 and in the U19s in 2006, 2007, 2010 and 2011. C/I bowlers bowled significantly fewer overs than W bowlers in the U13s in 2008 and 2009. Conclusion. The bowling averages of the different racial groups are similar. However, there were relatively few BA bowlers in the top 20 wicket takers each year. This could be because of a lack of highly skilled BA bowlers or the lack of opportunity provided to BA bowlers to bowl in these tournaments.

Magnetic resonance imaging of the iliac crest: age estimation in under-20 soccer players

Age assessment of living individuals represents a valuable tool in both forensic medicine and sports medicine. In soccer, age-related tournaments play an important role in guaranteeing equal chances to the competitors. However, age estimations in this field should not rely on imaging methods that include exposure to radiation. Therefore, the present study investigates the possibilities of magnetic resonance imaging (MRI) of the iliac crest apophysis for the purpose of evaluating skeletal maturation in under-20 (U-20) soccer players. To this end, gradient echo 3D sequences of the whole pelvis of 152 male tournament soccer players between 18 and 22 years of age were prospectively evaluated. A four stage classification system was applied for the assessment of the apophyseal ossification. Reliable stage determination was possible in all cases. Further sub-classification did not appear feasible due to the limitations of MRI. Analysis of the statistical parameters showed that age medians increased steadily from stage to stage. However, they did not allow for further differentiation of skeletal maturity in the cohort studied. Thus, MRI of the iliac crest appears to be generally suitable in age diagnostics of living individuals, but further investigations, especially in a cohort of individuals aged between 10 and 20 years, are needed in order to establish this method as novel criterion in sports or forensic medicine.

The Relative Age Effect in the 2013 FIFA U-17 Soccer World Cup Competition

Purpose: The purpose of this study was to check the eventual existence of any Relative Age Effect (RAE) in the recent 2013’ FIFA Male Under-17 (U-17) World Cup Football tournament. The data pertaining to the players who participated in to that event were collected from the FIFA website. They included the players’ dates of birth (day, month and year) and position (goalkeeper, defender, midfielder or striker).The distributions of birth months were significantly different with more players born in the early months of the year compared with the later months. For the entire cohort of players, 38.7% were born in the first quarter of the year while only 10.5% were born in the last 3 months in the same year. This relative age effect held for all FIFA-designated teams except for the Nigeria and the Côte d'Ivoire having shown a reverse relative age effect. The results of this investigation show that at the highest level of youth soccer, the RAE still exists and is a strong bias toward inclusion of players born early in the concerned year.

Active control stabilization of pelvic position in the transverse plane: An evaluation of soccer players' performance

ObjectivesTo describe the capability of soccer players to stabilize pelvic position actively in the transverse plane; and, to evaluate the influence of lower limb dominance, length of exposure to soccer practice, and field position on pelvic stabilization capability. DesignCross-sectional. ParticipantsSixty-eight soccer players from under-15 (U-15) and professional categories. Main outcome measuresMagnitude and asymmetry of pelvic tilt in the transverse plane, evaluated using the bridge test with unilateral knee extension. ResultsThe magnitude of pelvic tilt did not differ between dominant and non-dominant sides, suggesting absence of relative asymmetry. However, there was difference between the sides of greater and lesser magnitude of pelvic tilt, indicating presence of absolute asymmetry. Players with shorter length of exposure to soccer practice (U-15 group) had greater pelvic tilt than players with longer length of exposure (professional group). There was no association of field position with the magnitude and asymmetry of pelvic tilt. ConclusionSoccer players showed asymmetry in pelvic stabilization capability that was unrelated to lower limb dominance or field position. Athletes with longer length of exposure to soccer practice present better capability to stabilize the pelvis in the transverse plane than those with shorter length of exposure to soccer practice.

Coaches’ and Players’ Perceptions of Training Dose: Not a Perfect Match

The aim of the current study was to investigate and compare coaches' and players' perceptions of training dose for a full competitive season. Session rating of perceived exertion (RPE), duration, and training load (session RPE × duration) of 33 professional soccer players (height 178.2 ± 6.6 cm, weight 70.5 ± 6.4 kg, percentage body fat 12.2 ± 1.6) from an under-19 and under-17 (U17) squad were compared with the planned periodization of their professional coaches. Before training, coaches filled in the session rating of intended exertion (RIE) and duration (min) for each player. Players rated session RPE and training duration after each training session. Players perceived their intensity and training load (2446 sessions in total) as significantly harder than what was intended by their coaches (P < .0001). The correlations between coaches' and players' intensity (r = .24), duration (r = .49), and load (r = .41) were weak (P < .0001). Furthermore, for coach-intended easy and intermediate training days, players reported higher intensity and training load (P < .0001). For hard days as intended by the coach, players reported lower intensity, duration, and training load (P < .0001). Finally, first-year players from the U17 squad perceived training sessions as harder than second-year players (P < .0001). The results indicate that young elite soccer players perceive training as harder than what was intended by the coach. These differences could lead to maladaptation to training. Monitoring of the planned and perceived training load of coaches and players may optimize performance and prevent players from overtraining.

MRI to determine the chronological age of Ghanaian footballers

Background. The chronological age of the ordinary Ghanaian has often been difficult to verify as registration at birth is not compulsory. Consequently, an accurate method of age determination is needed in competitive age-restricted sports.Objective. To evaluate the age of Ghanaian soccer players who are aspiring to play for the national under-17 (U17) team, using the degree of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football Association (FIFA) MRI grading.Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a ‘justify your inclusion tournament’ organised by the Ghana Football Association between June and August 2012. The study was conducted in a diagnostic centre in Accra using a 0.35T MRI scanner. The images were analysed using the previously published FIFA grading system.Results. The mean chronological age of the players was 15.4 years (standard deviation ±0.7; range 12 - 17). The study showed that 43.0% of the MRI images were grade 6 (≥17 years) in relation to the degree of fusion of the distal radius, and 93.0% of the grade 6 players were aged 15 - 16 years chronologically. There was no significant correlation between the chronological age and the degree of fusion (r=0.075; p=0.493).Conclusion. Ghanaian U17 soccer players seem to be more biologically mature than a normative population of the same age category. The lack of correlation between age category and degree of fusion supports the suspicion that most Ghanaian players may not know their true age.

MRI to determine the chronological age of Ghanaian footballers

Background. The chronological age of the ordinary Ghanaian has often been difficult to verify as registration at birth is not compulsory. Consequently, an accurate method of age determination is needed in competitive age-restricted sports.Objective. To evaluate the age of Ghanaian soccer players who are aspiring to play for the national under-17 (U17) team, using the degree of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football Association (FIFA) MRI grading.Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a ‘justify your inclusion tournament’ organised by the Ghana Football Association between June and August 2012. The study was conducted in a diagnostic centre in Accra using a 0.35T MRI scanner. The images were analysed using the previously published FIFA grading system.Results. The mean chronological age of the players was 15.4 years (standard deviation ±0.7; range 12 - 17). The study showed that 43.0% of the MRI images were grade 6 (≥17 years) in relation to the degree of fusion of the distal radius, and 93.0% of the grade 6 players were aged 15 - 16 years chronologically. There was no significant correlation between the chronological age and the degree of fusion (r=0.075; p=0.493).Conclusion. Ghanaian U17 soccer players seem to be more biologically mature than a normative population of the same age category. The lack of correlation between age category and degree of fusion supports the suspicion that most Ghanaian players may not know their true age.

Injuries in elite youth football players: a prospective three-year study

The aim of this study was to investigate the incidence and nature of injuries and the influence of age on injury patterns in elite youth football. Fifty-two players of the Under-17 (U-17) male national youth football team were followed during their progression to U-18 and U-19. Individual player exposure and injuries were recorded during the three year study period. Injury incidence was five times higher during matches than training. When medical attention and time loss injuries were considered, injury incidence increased during matches and decreased during training with increasing age. Traumatic injuries were more frequent in matches and were linked with increased age. Overuse injuries were two times higher during training than matches in the U-17 team. The majority of traumatic match injuries (78.3%) led to time loss and the majority of time loss injuries occurred due to traumatic mechanism (62.1%). The majority of muscle and entire ligament injuries occurred during training and contusions during competition. Re-injury rate was 25% and were all overuse injuries. Injury incidences increased during matches and decreased during training. More match injuries were caused by traumatic mechanisms as players aged. Player age might contribute to injury incidence and characteristics in youth football.

MRI to determine the chronological age of Ghanaian footballers

Background. The chronological age of the ordinary Ghanaian has often been difficult to verify as registration at birth is not compulsory. Consequently, an accurate method of age determination is needed in competitive age-restricted sports.Objective. To evaluate the age of Ghanaian soccer players who are aspiring to play for the national under-17 (U17) team, using the degree of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football Association (FIFA) MRI grading.Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a ‘justify your inclusion tournament’ organised by the Ghana Football Association between June and August 2012. The study was conducted in a diagnostic centre in Accra using a 0.35T MRI scanner. The images were analysed using the previously published FIFA grading system.Results. The mean chronological age of the players was 15.4 years (standard deviation ±0.7; range 12 - 17). The study showed that 43.0% of the MRI images were grade 6 (≥17 years) in relation to the degree of fusion of the distal radius, and 93.0% of the grade 6 players were aged 15 - 16 years chronologically. There was no significant correlation between the chronological age and the degree of fusion (r=0.075; p=0.493).Conclusion. Ghanaian U17 soccer players seem to be more biologically mature than a normative population of the same age category. The lack of correlation between age category and degree of fusion supports the suspicion that most Ghanaian players may not know their true age.

Time–Motion and Physiological Profile of Football Training Sessions Performed by Under-15, Under-17, and Under-19 Elite Portuguese Players

To provide the time-motion and physiological profile of regular training sessions (TS) performed during the competitive season by under-15 (U15), under-17 (U17), and under-19 (U19) elite-level Portuguese soccer players. One hundred fifty-one elite players of U15 (age 14.0 ± 0.2 y, n = 56), U17 (age 15.8 ± 0.4 y, n = 66), and U19 (age 17.8 ± 0.6 y, n = 29) participated in the study during a 9-wk period. Time-motion and body-impact data were collected using GPS technology (15 Hz) across 38 randomly selected TS that resulted in a total of 612 samples. In addition, heart rate (HR) was continuously monitored (1 Hz) in the selected TS. The total distances covered (m) were higher in U17 (4648.3 ± 831.9), followed by U19 (4212.5 ± 935.4) and U15 (3964.5 ± 725.4) players (F = 45.84, P < .001). Total body impacts and relative impacts were lower in U15 (total: 490.8 ± 309.5, F = 7.3, P < .01), but no differences were identified between U17 (total: 584.0 ± 363.5) and U19 (total: 613.1 ± 329.4). U19 players had less high- and very-high-intensity activity (above 16 km/h; F = 11.8, P < .001) and moderate-intensity activity (10.0-15.9 km/h; F = 15.07, P < .001). HR values showed significant effects of zone (F = 575.7, P < .001) and interaction with age group (F = 9.7, P < .001), with pairwise differences between all zones (zone 1, <75%; zone 2, 75-84.9%; zone 3, 85-89.9%; zone 4, ≥90%). All players spent most of their time below 75% HRmax (U15, ~50%; U17, ~42%; U19, ~50%). Results showed high variability between TS, refraining from identifying meaningful trends when measuring performance, although different demands were identified according to age group. The U15 TS were less physiologically demanding, probably because of increased focus on small-sided games to develop basic tactical principles and technical skills. The focus on game-like situations imposed higher external and internal workloads on U17 and U19 players.

Correlações entre parâmetros aeróbios e desempenho em esforços intermitentes de alta intensidade

O objetivo do presente estudo foi investigar as possíveis correlações entre parâmetros provenientes de um esforço intermitente de alta intensidade (RAST) e variáveis relacionadas ao metabolismo aeróbio (limiar anaeróbio; LAN, consumo máximo de oxigênio;VO2MAX e intensidade correspondente ao VO2MAX;iVO2MAX). Oito jogadores de futebol (16±1 anos) participaram do estudo. Os atletas foram submetidos a um teste progressivo para a determinação dos índices aeróbios e a seis esforços máximos de 35m separados por 10s de recuperação (RAST). As variáveis do RAST não foram correlacionadas ao VO2MAX e ao LAN. Entretanto, as potência média absoluta e relativa ao peso corporal, apresentaram correlações significativas com a iVO2MAX (r=0,79 e r= 0,85, respectivamente). O índice de fadiga e a potência pico relativa também foram significativamente correlacionados com a iVO2MAX (r=-0,57 e r=0,73, respectivamente). Pode-se concluir que em esforços como o RAST, com breves períodos de recuperação, a única variável aeróbia correlacionada ao desempenho foi a iVO2MAX.

Kicking velocity and physical, technical, tactical match performance for U18 female football players – Effect of a new ball

We investigated kicking velocity and physical, technical, and tactical match performance for under-18 (U18) female football players and evaluated the effect of using a newly developed lighter smaller ball. Ten regional league teams participated. Maximal ball velocity was 4±1% higher when kicking the new ball (NB) compared with the standard ball (SB) in a laboratory testing situation (23.2±0.4 vs. 22.4±0.3ms−1; p<.05). Mean HR was similar during games with NB and SB (169±2 vs. 170±2bmin−1; p>.05), but lower-limb muscular RPE was lower with NB (4.2±0.4 vs. 5.2±0.3; p<.05). The number of activity changes (1387±76 vs. 1401±55), total distance covered (9.09±0.25 vs. 9.11±0.25km) and high-intensity running (1.04±0.08 vs. 1.11±0.07km) were not different between NB and SB (p>.05). High-intensity running decreased (p<.05) from 0–20 to 60–80min with NB (34%) and SB (37%). The number and success rate of long and short passes did not differ between NB and SB (p>.05). In conclusion, physiological demands were high in youth female football games, and decrements in running performance occurred towards the end of games. The players kicked faster and reported lower muscular exertion during games played with a lighter smaller ball, but locomotor activities, heart rate and overall technical-tactical game performance remained unaffected.

Anthropometric Characteristics, Physical Fitness and Technical Performance of Under-19 Soccer Players by Competitive Level and Field Position

Anthropometric characteristics, physical fitness and technical skills of under-19 (U19) soccer players were compared by competitive level (elite, n=95; non-elite, n=85) and playing position (goalkeeper, central defender, fullback, midfield, forward). Fitness tests included 5- and 30-m sprints, agility, squat jump (SJ) and countermovement jump (CMJ), strength and Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2). Soccer-specific skills included ball control and dribbling. Independent of position, elite players presented more hours of training per year than non-elite players (d>1.2). Stature and body mass discriminated elite from non-elite players among goalkeepers and central defenders (d>0.6). Major differences were noted between elite and non-elite goalkeepers for SJ, CMJ, Yo-Yo IE2, and ball control (d>1.2). Elite central defenders performed better than their non-elite counterparts in SJ and ball control tests (d>1.2). Elite players presented better agility and Yo-Yo IE2 performances than non-elite players within all positional roles (d>0.6). In conclusion, U19 players differed in anthropometric characteristics, physical fitness and technical skills by competitive level within field positions.

Sport selection in under-17 male roller hockey

Characteristics of 32 international and 41 local under-17 (U-17) (14.5–16.5 years) roller hockey players were considered in the context of discrimination by competitive level using training history, anthropometry, skeletal maturation, and several laboratory and field performance tests. More international (42%) than local (22%) players were advanced in maturity status. International players had slightly less hockey experience (years), but had more practice sessions and match time (minutes) during the season. Local players were shorter and attained better performance in the 25-m dash, while international players performed better in sit-ups, ball throw and 20-m shuttle run. The fatigue index derived from the Wingate anaerobic test was higher among local players, while peak torques of knee extension and flexion were greater in international players. Stepwise discriminant function correctly classified 85% of players by competitive level based on grip strength, ratio of eccentric and concentric knee extension, number of training sessions, playing time and fatigue index. The results suggested an interaction among strength, anaerobic fitness and training plus game time as factors in discriminating international from local level players and by inference in the selection and development of youth roller hockey players.

Quantification of the typical weekly in-season training load in elite junior soccer players

We examined the typical weekly training load experienced by elite junior soccer players during the in-season competitive period. Altogether, eight under-14 (U14), eight under-16 (U16) and eight under-18 (U18) players were monitored over a 2-week period during the first month of the 2010–11 competitive season. This time period included one competitive match per week. Physiological loading was monitored using heart rate (HR) and ratings of perceived exertion (RPE). Training and match loads were calculated by multiplying the global session RPE and duration (session-RPE). Total weekly training load (training and match) increased with age (U14, 2524 ± 128 arbitrary units [AU]; U16, 2919 ± 136 AU; U18, 3948 ± 222 AU; P < 0.05). Differences in the daily training load across the training week were also evident in the older age group relative to both U14 and U16. The amount of time engaged in low (<50% HRmax) and high (>90% HRmax) intensity activity during training and match-play was significantly lower and higher respectively in the U18 compared to the U14 group (P < 0.05). When comparing activity, the intensity (% HRmax) of field training (U18, 69 ± 2%; U16, 74 ± 1%; U14, 74 ± 2%) was significantly lower compared to match-play (U18, 81 ± 3%; U16, 84, ± 2%; U14, 83 ± 2) across all age groups (P < 0.05). Findings demonstrate that age related differences in the volume and intensity of weekly in-season training load are evident amongst elite professional junior soccer players. These differences may reflect a systematic approach to the long-term physical development of elite junior players.

The predictive value of on-ice special tests in relation to various indexes of aerobic and anaerobic capacity in ice hockey players

PurposeThe main goal of this study was to determine the predictive value of the indexes of aerobic and anaerobic endurance in relation to specific on-ice tests performed by hockey players that focus on strength, power, speed as well as speed and strength endurance.MethodsIce hockey players, who were members of the U20 (under 20 years of age) Polish National Ice Hockey Team, were selected from the Athletic School in Sosnowiec, Poland. Parameters that determine anaerobic and aerobic capacity were evaluated and a special physical fitness assessment was made based on a battery of ice-hockey specific tests. The degree and direction of correlations between the individual parameters of anaerobic and aerobic endurance and the special physical fitness test were calculated.ResultsThe obtained results found significant correlations between maximal power obtained from the Wingate test and certain aspects of the special physical fitness test, specifically the 6 × 9 turns, 6 × 9 stops and 6 × 30 m endurance tests. Significant correlations of the above-mentioned special physical fitness tests were also observed with the aerobic capacity parameter, VO&lt;sub&gt;2max&lt;/sub&gt;.ConclusionsThe obtained results could be considerably useful in training, as well as providing much more information on athletes which can then be suited for more personalized forms of training.

The lumbar spine of the young cricket fast bowler: An MRI study

ObjectivesTo describe the prevalence and nature of lumbar spinal abnormalities in adolescent cricket fast bowlers. DesignObservational study. Methods46 asymptomatic fast bowlers aged 13–18 years participated in the study and were grouped into under-15 (U15), under-17 (U17) and under-19 (U19) classifications. All participants underwent magnetic resonance imaging of the lumbar spine and abnormalities of the pars interarticularis and intervertebral discs were graded according to type and severity. Other abnormalities were also noted. ResultsFifteen bowlers (33%) had at least one pars interarticularis abnormality. Six bilateral and 10 unilateral defects were identified. Of the 10 unilateral pars abnormalities, 6 occurred on the non-dominant side. Nineteen of the abnormalities occurred at the L5 vertebral level, 2 at L4 and 1 at L3. The most common type of pars abnormality was the subtotal stress fracture, which was found in 38% of bowlers aged 16 years and under. Sixteen participants (35%) were found to have degeneration of at least 1 lumbar disc and the prevalence increased with each successive age group (29% U15, 33% U17 and 43% U19). Of the 25 discs with signs of degeneration, 9 occurred at L4/5 and 7 at L5/S1. Eleven of these were classified as mild degeneration, 13 as moderate, and 1 as severe. Disc bulges were found in 33% of participants. ConclusionsLumbar radiological abnormalities are common in asymptomatic adolescent fast bowlers. Acute bone stress reactions of the lumbar pars interarticularis are visible on magnetic resonance imaging and, in some instances, occur before the onset of activity-related pain.