Effects of two different short-term training programs on the physical and technical abilities of adolescent basketball players

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1 Journal of Science and Medicine in Sport (2007) 10, ORIGINAL PAPER Effects of two different short-term training programs on the physical and technical abilities of adolescent basketball players Gregory C. Bogdanis b,, Vaghelis Ziagos a, Michalis Anastasiadis a, Maria Maridaki b a Department of Team Sports, Faculty of Physical Education and Sports Science, Athens, Greece b Department of Sports Medicine and Biology of Physical Activity, Faculty of Physical Education and Sports Science, 41 Ethnikis Antistasis Street, Dafni, Athens, Greece Received 21 November 2005; received in revised form 5 May 2006; accepted 8 May 2006 KEYWORDS Sport-specific training; Anaerobic; Aerobic Summary This study evaluated and compared the effectiveness of two different off-season, short-term basketball training programs on physical and technical abilities of young basketball players. Twenty-seven adolescent basketball players (14.7 ± 0.5 years; Tanner stage: 3.5 ± 0.5) were randomly divided into a specialized basketball training group (SP, n = 10), a mixed basketball plus conditioning training group (MX, n = 10) and a control group (n = 7). Training included five sessions per week ( min each) and was performed for 4 weeks. Maximal oxygen uptake was similarly improved after SP (4.9 ± 1.8%) and MX (4.9 ± 1.4%), but there was no effect on ventilatory threshold. Peak and mean power output measured during the Wingate test were also improved by a similar magnitude after SP (21 ± 5%) and MX (15 ± 6%). Trunk muscle endurance was equally increased (SP: 23 ± 4%, MX: 25 ± 5%), but arms endurance was improved significantly more after MX (50 ± 11%) compared to SP (11 ± 14%, p < 0.05). Performance in four basketball technical skills was similarly increased (by 17 27%) in both groups, with a tendency for greater improvement of the SP groups in the technical skills of shooting and passing. These results indicate that a SP basketball training program, performed exclusively oncourt was as effective as a MX training program in terms of aerobic and anaerobic fitness improvement. Furthermore, the decrease of the total on-court training time in the MX group resulted in a tendency for a smaller improvement of basketball technical skills. In conclusion, both SP and MX training are equally effective in order to limit and/or reverse the detraining effects that occur during the off-season in basketball Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Corresponding author. Tel.: ; fax: address: gbogdanis@phed.uoa.gr (G.C. Bogdanis) /$ see front matter 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi: /j.jsams

2 80 G.C. Bogdanis et al. Introduction In many team sports, such as football and basketball, the competitive season is followed by a prolonged period of low activity or complete inactivity. Thus, many athletes follow off-season training programs in order to limit the detrimental effects of detraining that may occur even after a few days of inactivity. 7,9 Although the effects of the prolonged competitive season on some physical and functional indices of basketball players have been investigated, 6,17,26 there are limited research data regarding the characteristics of an effective shortterm training program following the competitive season. 20 The positive influence of short-term training programs on several physical abilities (i.e. strength, endurance, anaerobic power, jumping ability, etc.) has been investigated using athletes of many sports, though the training interventions were implemented at different periods during the season and did not include sport-specific training contents. 1,29,33 Furthermore, several authors have shown that pre-pubescent and adolescent athletes and non-athletes can benefit from short-term training, demonstrating increases in aerobic power, 4,11 muscle strength, 12,16 anaerobic power, 10,30 jumping ability 10,28 and local muscle endurance. 12 However, only few studies have compared different short-term training programs, most commonly used in competitive sports practice. 14,20 Recent studies in junior soccer players 18,19,24 have suggested that sport-specific training and generic training may be equally effective for the improvement of aerobic fitness of soccer players. Despite the research data regarding the effectiveness of short-term training programs on the athletic performance of adolescent athletes and non-athletes, 12,14 the effects of specific basketball training interventions still remain unknown. Thus, the improvement of the physical and technical abilities of young basketball players during the off-season period is based more on the empirical knowledge, intuition and personal preferences of the coaches than on research data. The few studies referring to off-season training in basketball have focused on strength and conditioning aspects 20 and highlighted the importance of leg strength, speed and agility for basketball performance and preparation. 21 Although there is a tendency for many basketball and other team sport coaches to perform more sport-specific training during the preparation phase, 19 there is no experimental evidence to show that this practice is as effective as generic training in basketball. Therefore, this study was designed to compare the efficacy of two short-term basketball training programs (i.e. a sport-specific and a mixed program) for changes in physical and technical abilities in adolescent basketball players during the offseason training period. The sport-specific program was performed exclusively on the court, while the mixed program also included off-court strength and conditioning elements. It was hypothesized that both programs would be equally effective in improving aerobic and anaerobic fitness of the players, but that the sport-specific program would be superior in improving basketball technical abilities. Materials and methods Subjects Twenty-seven cadet (category under 16-year old) basketball players (mean age: 14.7 ± 0.5 years, height: 179 ± 6 cm, mass: 72.6 ± 8.6 kg) gave their informed consent and participated in the study that had the approval of the University Ethics Committee. Volunteers were recruited from two of the most successful teams participating in the Under-16 (cadet) national championships. All procedures conformed to the Code of Ethics of the World Medical Association. Maturity status was evaluated according to the development of pubic hair and external genitals and all the participants were classified in Tanner stages 3 4 (3.5 ± 0.3). Procedures Measurements were performed before and after a 4-week training period. The baseline measurements were performed 3 weeks after the end of the competitive period. During this 3- week period the subjects did not take part in any form of organized training. The participants were familiarized with the testing procedures during two preliminary visits. The main measurements were performed on four different sessions on separate days and included the evaluation of aerobic fitness (maximal oxygen uptake and ventilatory threshold), anaerobic power (30 s Wingate test), local muscle endurance of arms and trunk 8 and technical ability. 23 The post-training measurements were performed 2 7 days after the last training session and included all the above testing procedures in the same order.

3 Basketball training in adolescents 81 Training design Following the initial testing sessions, subjects were randomly divided into three groups (two experimental groups, n = 10 each, and a control group n = 7). Two different training programs ( Specialized, SP and Mixed, MX) were applied for 4 weeks in the two experimental groups, while the control group (C) did not participate in any form of training. Both training programs included five training sessions per week, each lasting min. The main training aim during the on-court training was common in both programs, but was different for each week, shifting from the improvement of fundamental skills in week 1 to the development of basic offensive/defensive cooperations between players in week 4 (Table 1). The two groups were trained by the same two head coaches and three assistants, who were present during each training session of the SP and MX group. Motivation was similar and consistent for both training groups. Specialized training program The daily practice of the SP training program was performed exclusively on the basketball court and included drills and exercises on the fundamental skills, such as dribbling, passing and shooting drills, as well as individual offensive and defensive cooperations between two and three players and half and full court 5 versus 5 game. The warm-up exercises were also performed on the court (with and without the ball), had progressive intensity and were followed by a 5-min stretching period. The mean percentage contribution of the components of each session to the total session duration is shown in Table 1. Mixed training program The structure of the daily practice of the MX training program was similar to that of the SP program. However, the duration of the fundamental skills, individual work, team work and offensive/defensive co-operations between players was 20 40% shorter in the MX, because circuit training was also performed in each session of the MX (Table 1). Circuit training aimed to improve upper and lower body strength and power of the players and included three cycles, each one consisting of five or six exercises of the following 10: rope skipping, abdominal crunches, full sit-ups, push-ups, drop jumps, repeated vertical jumps to the backboard with maximal effort, hurdle hops, medicine ball drills (passing and throwing) and power shuffle. Both upper and lower body exercises of the above were included in each circuit training session. Players were asked to perform as many repetitions as possible in the allocated time with special attention to perform the movement correctly. The number of repetitions was recorded for each exercise and player and this was used to confirm the effort of each player in each circuit training session. Every exercise lasted progressively from 15 to 30 s (a 5 s increase per week). The interval between the exercises was gradually reduced from 45 to 30 s (a 5 s reduction per week), whereas the interval between the cycles was 3 min. During the first week the circuit training was included in each one of the five MX sessions. However, most subjects found it very hard to perform circuit training in every session, and thus the circuit training sessions were reduced from five to four per week from week 2. The day-off circuit training granted was the middle of the 5 days (Wednesday). Thereby, one of the 5 days of the weekly training program Table 1 duration The mean percentage contribution (per week) of the components of each session to the total session Week 1 Week 2 Week 3 Week 4 Mean SP MX SP MX SP MX SP MX SP MX Warm-up ± ± 1.3 Fundamentals ± ± 7.1 Individual work ± ± 7.1 Off.-def. coop ± ± 6.6 Team work ± ± 1.6 Cool-down ± ± 0.6 Circuit training ± 0.7 Total SP: specialized; MX: mixed training group; Off.-def. coop.: offensive/defensive co-operations between players.

4 82 G.C. Bogdanis et al. of the MX group was common with that of the SP group. Training intensity Training intensity was evaluated by continuously monitoring heart rate (HR) during each training session (Excel Sport PC, Cardiosport HealthCare Technology). HR data were stored as 1 min averages and were expressed as percent of maximal HR (%HR max ). Training intensity was quantified by calculating the training time spent at the following six intensity zones according to %HR max : <70%, 70 80%, 80 85%, 85 90%, 90 95% and >95%. Also, the training time corresponding to low intensity exercise, i.e. below ventilatory threshold 1 (VT1), moderate intensity exercise, i.e. between VT1 and ventilatory threshold 2 (VT2) and high intensity, i.e. above VT2, was calculated. 27 Finally, training impulse (TRIMP) scores were calculated. 3,13 Measurements Aerobic fitness test Maximal oxygen uptake (VO 2max ) was determined using a progressive treadmill test with a constant speed of 8 km h 1 and initial grade 1%, which was increased by 1% every minute. VO 2max was defined as the highest 30 s average of VO 2 during the test if at least two of the following criteria were satisfied: (a) a plateau of VO 2 (<2 ml kg 1 min 1 increase) despite an increase of treadmill grade, (b) inability to maintain the running speed, (c) the respiratory exchange ratio was greater than 1.1, (d) HR was >95% of the predicted maximum corrected for age. Measures of gas exchange were obtained by an open-circuit automatic spirometric system (Medgraphics, CPX/D, USA) interfaced with a computer. The first ventilatory threshold (VT1) was determined by the computer software using the V-slope method 5 and the respiratory compensation threshold (VT2) was detected from the ventilation (VE) versus CO 2 output (VCO 2 ) plot, as well as by an increase in both the VE VO 1 2 and VE VCO 1 2 and a decrease in end tidal pressure of CO 2. Both thresholds were verified by experienced researchers. The coefficient of variation for the detection of the thresholds is <3%. 5 The intraclass correlation coefficient (ICC) for VO 2max, VT1 and VT2 were 0.94, 0.90 and 0.97, respectively. The subject s HR was continuously recorded during the test (Excel Sport PC, Cardiosport Health- Care Technology) and HR at VT1 and VT2 were recorded. Anaerobic power test Two days after the aerobic test, subjects performed a 30 s Wingate Anaerobic Test on a Monark 864 cycle ergometer, interfaced with a computer. Power output was averaged every 5 s and the highest 5 s block was designated as peak power output (PPO), while mean power output (MPO) was the 30 s average mechanical power. PPO and MPO were expressed both as absolute (W) and relative values (W kg 1 ). The fatigue index was calculated as the difference between the highest (PPO) and the lowest 5 s power output block, expressed as a percentage of PPO. This laboratory-based test has been previously used to assess anaerobic power and capacity in basketball players, and both PPO and MPO are positively correlated with basketball-specific field tests such as the line drill and the vertical jump. 22 The ICC for PPO and MPO were both The protocol included a 5 min standardized warm-up (cycling at 60 rpm against a frictional load of 1 kg), followed by two 3 4 s all-out sprints with a 1 min interval in between. After a 5 min resting period, the subject started pedalling as fast as possible against no resistance. When maximal speed was attained, the resistance (75 g kg body mass 1 ) was applied and the measurement started. Subjects were verbally encouraged to maintain maximal speed throughout the 30-s period. Trunk and arms muscle endurance tests Muscle endurance of trunk and arms was measured by two standard outdoor tests from the Eurofit test battery 8 : the 30 s sit-up test for abdominal muscle endurance and the bent arm hanging test on a horizontal bar for arms and shoulder muscle endurance. The score for the sit-up test was the number of the sit-ups performed in 30 s, while the arm and shoulder muscle endurance was defined as the time that the subject remained with the eye level above the horizontal bar with the hands shoulder-wide and a forward grip. The ICC for both tests was Technical abilities evaluation The technical abilities of the participants in this study were evaluated by the basketball skills test of the American Alliance for Health, Physical Education, Recreation and Dance (AAHPERD). 23 This included four different items, each one evaluating a fundamental technical ability in basketball: speed shot shooting (ICC: 0.86), passing (ICC: 0.95), dribbling (ICC: 0.93) and defensive sliding (ICC: 0.96). The validity and reliability of this test has been previously established for players between 10 and 18 years old. 23 Briefly, these tests recorded the successful shots from different positions in 60 s (shooting test), the successful passes at different targets

5 Basketball training in adolescents 83 while moving in 30 s (passing test) and the time to cover a specified track in the court while dribbling (dribble test) and moving with side steps without crossing the feet (defensive sliding test). Statistical analyses Normal distribution of all variables was checked using the Kolmogorov Smirnov test. Changes in fitness parameters and technical abilities were assessed using two-way analysis of variance (group test) with repeated measures on one factor (test). When significant F ratios were found for main effects or interaction (p < 0.05), the means were compared using Tukey s post hoc tests. Effect size (ES) was also estimated for main effects and interaction by calculating partial eta squared values using the SPSS v.11 statistical package. Correlations between variables were examined by calculating the Pearson s correlation coefficient (r). Results are presented as mean ± standard error (S.E.). Figure 1 Percentage of training time spent at different intensity zones defined according to the percentage of maximum heart rate (%HR max ) for the specialized (SP) and mixed training (MX) groups. Values are means ± S.E. for the 4 weeks of training. Results Training load was similar in the SP and MX group throughout the 4 weeks of training. No significant differences between groups were found for the TRIMP scores per week or the mean TRIMP scores for the 4-week training period (SP: 305 ± 5 and MX: 310 ± 5 arbitrary units). Furthermore, the percent of training time spent at low, moderate and high intensity was also similar in the two groups (low intensity: 58.4 ± 3.0 versus 64.2 ± 2.7%; moderate intensity: 37.0 ± 2.4 versus 32.6 ± 2.3%; high intensity: 4.6 ± 1.2 versus 3.2 ± 1.0% for the SP and MX group, respectively). Fig. 1 shows the mean training time spent by the two groups in various intensity zones during the 4 weeks of training. No differences were found between groups for all training zones. There were no significant differences between the three groups in the pre-training values of VO 2max and VT (Table 2). Both short term training programs had a similar, relatively small, but statistically significant effect on VO 2max (SP: 4.9 ± 1.8% versus MX: 4.9 ± 1.4%, ES = 0.22, small ), but there was no effect on VT expressed in absolute or relative values (Table 2). Significant negative correlations were found between the pre-training level of VO 2max and the percentage improvement in VO 2max in both training groups (SP: r = 0.96, p < 0.01; MX: r = 0.74, p < 0.05, pooled SP and MX data: r = 0.86, p < 0.01). No changes in aerobic fitness parameters were observed for the C group. Maximum HR and HR at VT1 and VT2 did not change in all groups after the 4 weeks of training (Table 1). PPO and MPO were improved with both training programs ( medium ES = 0.55 and 0.53, respectively), while there was no change in power output for the C group (Fig. 2). The percent increases in PPO and MPO were 21 ± 5% in the SP and 15 ± 6% Table 2 Maximal oxygen uptake (VO 2max ), oxygen uptake the first (VT1) and second ventilatory threshold (VT2), maximal heart rate (HR max ) and heart rate at VT1 (HR VT1 ) and VT2 (HR VT2 ), before (PRE) and after (POST) training SP MX C PRE POST PRE POST PRE POST VO 2max (ml kg 1 min 1 ) 52.3 ± ± 0.7 * 52.5 ± ± 1.0 * 49.8 ± ± 3.4 VT1 (ml kg 1 min 1 ) 33.9 ± ± ± ± ± ± 2.8 VT2 (ml kg 1 min 1 ) 43.5 ± ± ± ± ± ± 2.9 HR max (b min 1 ) 201 ± ± ± ± ± ± 3 HR VT1 (b min 1 ) 163 ± ± ± ± ± ± 3 HR VT2 (b min 1 ) 184 ± ± ± ± ± ± 4 Values are mean ± S.E. * p < 0.05 from the corresponding pre training value.

6 84 G.C. Bogdanis et al. Figure 2 (a) Peak (PPO) and (b) mean power output (MPO) relative to body mass of the control group (C) and the specialized (SP) and mixed training (MX) groups before (pre) and following 4 weeks of training (post). Values are mean ± S.E. ** p < 0.01 and * p < 0.05 from the corresponding pre training value. in the MX group, with no significant differences between the two groups. Strong negative correlations were found between the pre-training power output (PPO and MPO per kg body mass) and the percentage increase in power output after training (SP: r = 0.90 and 0.92, p < 0.01; MX: r = 0.88 and 0.91, p < 0.01 for PPO and MPO, respectively). The fatigue index during the Wingate test was not different between groups before training (47.2 ± 2.3% and 50.1 ± 1.7%) and remained unchanged after training (46.8 ± 2.0% and 50.9 ± 2.4%) despite the increase in PPO. It must be noted that body mass did not change in any of the groups (<0.4 kg change). The percent changes in trunk and arms muscle endurance are presented in Fig. 3. Trunk muscle endurance of both experimental groups changed significantly after the 4-week training period (20.8 ± 1.4 to 25.5 ± 1.7 sit-ups, p < 0.01 for the SP group and 22.6 ± 2.0 to 28.1 ± 1.4 sit-ups, p < 0.05 for the MX group, ES = 0.64, medium ), without significant differences between the two training groups. Both the SP and the MX groups showed a significant improvement in arms muscle endurance (SP: 25.6 ± 4.6 to 28.5 ± 3.6 s, p < 0.05 and MX: 21.3 ± 3.4 to 31.9 ± 4.9 s p < 0.01, ES = 0.45, medium ). Post-hoc analysis indicated a greater improvement for the MX group compared with the SP group for arms muscle endurance (p < 0.05, ES = 0.21, small ). Due to technical problems during the post-training testing period, the measurement of arms muscle endurance for the C group was not performed for all subjects and is not presented. Each of the four basketball skills measured by the AAHPERD skill test was significantly and similarly improved (p < 0.01) for the SP and MX groups, while the C group did not show any significant improvement (Fig. 4). The ES for shooting, passing, dribbling and sliding were all medium, i.e. 0.58, 0.75, 0.49 and 0.59, respectively. Significant negative correlations were found between power output during the Wingate test (PPO and MPO per kg body mass) and the performance time for the dribbling and the defensive sliding skill tests both before and after training (r = 0.58 to 0.70, p < 0.01; pooled MX and SP group data, n = 20). The percent improvement in PPO and MPO was moderately correlated with the percent Figure 3 Percent improvement in trunk and arms muscular endurance of the control group (C) and the specialized (SP) and mixed training (MX) groups following 4 weeks of training. Values are mean ± S.E. * p < 0.05 between the specialized and the mixed training group.

7 Basketball training in adolescents 85 Figure 4 Percent improvement in technical abilities of the control group (C) and the specialized (SP) and mixed training (MX) groups following 4 weeks of training. Values are mean ± S.E. improvement in the dribbling and the defensive sliding skill tests (r = , p < , respectively; pooled MX and SP group data, n = 20). Discussion The aim of this study was to examine the effectiveness of two different short-term training programs performed after the end of the season, on the physical and technical abilities of adolescent basketball players. One main finding of the present study was that both the SP and the MX training programs increased anaerobic power by a similar magnitude (Fig. 2). Although similar improvements of performance during the Wingate test have been reported following interval training in children and youth, 15,30 this is the first study that quantified changes of anaerobic performance following short-term basketball training. The magnitude of the changes in anaerobic power (15 21%) was relatively large compared to other studies of similar and/or longer duration, probably as a result of the characteristics of the training program. In a study by Grodjinovsky et al. 15 the training effect was about 5% following 6 weeks of training which included three min segments per week within the regular physical education classes. On the other hand, Rotstein et al. 30 reported that a 9-week interval training program increased the MPO and PPO measured during the Wingate test by 10% and 14%, respectively. One possible explanation for the greater improvement of anaerobic power observed in the present study compared to previous studies may be the higher frequency of training (five times per week) compared with three times per week in the previous studies. 15,30 Another factor that may influence the magnitude of the response to training is the pre-training level of anaerobic fitness. In the present study, training started following a 3-week abstention from organized training following the end of the season. Thus, it is possible that anaerobic power was decreased when the baseline measurement was performed, in comparison to the end of the season, and this resulted in a large response following the 4-week training protocols. A decrease of performance during the Wingate test by about 10% after 3 weeks of detraining has been reported for recreationally strength trained men who were previously trained for 2 4 days per week. 25 The influence of the pre-training level of anaerobic fitness on the magnitude of response to training is also indicated by the high negative correlations (r = 0.88 to 0.92) between pre-training power output and percentage increase in power after training. The similar improvement of the anaerobic power in the SP and MX groups may have significant practical applications for the coaches and athletes. This finding suggests that basketball training performed exclusively on the court offers adequate stimulus for the improvement of anaerobic power of the legs and thus no additional off-court training was necessary at this phase of the training year. Of course, these findings should be interpreted with caution because other types of training, such as strength training and plyometrics, have been shown to improve important aspects of sport-specific fitness in adolescent athletes and young athletes. 14,28,32 Although the concept that the SP training is equally effective as MX training is appealing, generalization of the findings of the present study for other periods of the training year should be validated by further research, while the results of the present study may only be applicable for the off-season period. Furthermore, the lack of vertical jump measurements in the present study may be considered as a limitation. A greater improvement in vertical jumping ability after the MX training cannot be excluded, since circuit training included some plyometric training elements. A relatively small but significant improvement of aerobic fitness was observed following both SP and MX training programs (SP: 4.9 ± 1.8%; MX:

8 86 G.C. Bogdanis et al. 4.9 ± 1.4%). The training programs in the present study were not specifically designed to improve VO 2max, and probably the aerobic stimuli of basketball training were not adequate for a more substantial improvement of aerobic power. Rowland 31 states that children may need greater exercise intensities than adults (approximately 85% HR max ) in order to have significant aerobic adaptations. Furthermore, Helgerud et al. 18 and Hoff and Helgerud 19 have suggested that training intensity for aerobic soccer training should be performed at an intensity corresponding to 90 95% of HR max. In the present study, only a small fraction of the training time (5 7%) was spent at intensities above 90% of HR max (Fig. 1) or above VT2 and this was probably not adequate for a greater increase in VO 2max. A recent study comparing specific and generic aerobic training in soccer 24 has reported a 7% increase in VO 2max after 4 weeks for both types of training. However, in that study, the time spent at HR zones above 90% HR max was almost double compared with the present study. The fact that VT was not improved after the short-term basketball training in the present study, provides further support to the notion that the aerobic stimuli were not adequate. A previous study by Bangsbo and Mizuno 2 showed that 4 weeks of high-intensity aerobic training performed after a 3-week detraining period were not sufficient to restore the levels of citrate synthase and -hydroxy acyl CoA dehydrogenase. This would imply that muscle oxidative enzymes and consequently the lactate and ventilatory threshold, may require a longer time to improve. Arms and trunk local muscle endurance, as measured by the Eurofit testing battery, was significantly improved in both experimental groups. However, arm muscle endurance was improved significantly more in the MX group compared with the SP group. This probably reflects the effectiveness of the circuit training program on the improvement of local muscle endurance of the arms and demonstrates the concept of the specificity of training stimulus. 12 However, Hoffman 21 has reported that an above average arm strength does not appear to offer any further advantage in basketball playing time. Trunk muscle endurance was equally improved in both training groups. The effectiveness of the SP training program, which did not include any specific trunk muscle endurance exercises, may be worth further investigation. One possible explanation is that the synergistic action of the trunk muscle groups during basketball training was adequate to cause such an alteration in trunk muscle endurance. Performance in all four basketball technical skills was similarly improved in both experimental groups. One interesting aspect of the results was the tendency for a greater improvement in the technical skills of shooting and passing for the SP group compared with the MX training group (p = 0.08; ES = 0.19, small ; Fig. 4). This may be explained by the greater amount of time devoted for technical training in the SP training group compared to the MX training group (Table 1). On the other hand, the similar improvement in the technical abilities of dribbling and sliding in both training groups may be related to the nature of these tests. These tests rely more on speed and anaerobic fitness, since players have to perform the drill as fast as they can. Furthermore, the duration of these two drills was about s and thus anaerobic metabolism is heavily engaged. It can, therefore, be argued that the similar improvement in the dribbling and the sliding drill in the two training groups is related to the similar improvement in anaerobic fitness. This is reflected by the comparable improvements in PPO and MPO (Fig. 2) and the positive correlations found between percent improvement in power output and the dribbling and defensive skill tests (r = , p < 0.05 and 0.01, respectively). In conclusion, the results of the present study showed that both the SP and the MX short-term, off-season training programs, resulted in similar improvements of aerobic fitness and anaerobic power of adolescent basketball players. The inclusion of a daily min circuit training program did not result in any further improvements of fitness with the exception of arm endurance. These results indicate that a SP basketball training program, performed exclusively on-court, was as effective as a MX training program in terms of aerobic and anaerobic fitness improvement. There was a tendency for greater improvement of the SP groups in the technical skills of shooting and passing, and therefore the decrease of the total on-court training time due to the inclusion of circuit training resulted in a tendency for a smaller improvement of basketball technical skills in the MX group. Therefore, both SP and MX training are equally effective in order to limit and/or reverse the detraining effects that occur during the off-season that follows the competitive period in basketball. However, possible positive effects of an off-court conditioning program on fitness aspects that were not tested in the present study (e.g. throwing and jumping) as well as on injury prevention cannot be excluded and warrant further investigation.

9 Basketball training in adolescents 87 Practical implications Aerobic and anaerobic fitness of young basketball players can be significantly improved during the off-season using only specialized basketball training performed exclusively on the court. The inclusion of an off-court strength and conditioning program in the form of circuit training does not result in an additional improvement of aerobic and anaerobic fitness during this training period. The decrease of the total on-court training time when additional strength and conditioning training is performed, results in a tendency for a smaller improvement of basketball technical skills. Acknowledgements The authors would like to thank Z. Pafili and A. Papaspyrou for their technical assistance during the study. References 1. Balabinis CP, Psarakis CH, Moukas M, Vassiliou MP, Behrakis PK. Early phase changes by concurrent endurance and strength training. J Strength Cond Res 2003;17: Bangsbo J, Mizuno M. Morphological and metabolic alterations in soccer players with detraining and retraining and their relation to performance. In: Reilly T, Lees A, Davids K, Murphy WJ, editors. Science and football. London New York: E and FN Spon; p Banister EW. Modeling elite athletic performance. In: Mac- Dougal JD, Wenger HA, Green HJ, editors. Physiological testing of the high-performance athlete. Champaign, IL: Human Kinetics Books; p Baquet G, Berthoin S, Dupont S G., Gerbeaux M, van Praagh E. Effects of high intensity intermittent training on peak VO 2max in prepubertal children. Int J Sports Med 2002;23: Beaver WL, Wasserman K, Whipp BJ. A new method for detecting anaerobic threshold by gas exchange. J Appl Physiol 1986;60: Bolonchuk WW, Lukaski HC, Siders WA. The structural, functional and nutritional adaptation of college basketball players over a season. J Sports Med Phys Fitness 1991;31: Costill DL, Fink WJ, Hargreaves M, Kings DS, Thomas R, Fielding R. Metabolic characteristics of skeletal muscle during detraining from competitive swimming. Med Sci Sports Exerc 1985;17: Council-of-Europe, editor. Eurofit: European test of physical fitness. Strasbourg: Council of Europe, Committee for the Development of Sport; Coyle EF, Martin 3rd WH, Sinacore DR, Joyner MJ, Hagberg JM, Holloszy JO. Time course of loss of adaptations after stopping prolonged intense endurance training. J Appl Physiol 1984;57: Diallo O, Dore E, Duche P, van Praagh E. Effects of plyometric training followed by a reduced training programme on physical performance in prepubescent soccer players. J Sports Med Phys Fitness 2001;41: Docherty D, Wenger HA, Collis ML. The effects of resistance training on aerobic and anaerobic power of young boys. Med Sci Sports Exerc 1987;19: Faigenbaum AD, LaRosa Lou R, O Connell J, Glover S, O Connell J, Westcott WL. Effects of different resistance training protocols on upper-body strength and endurance development in children. J Strength Cond Res 2001;15: Foster C, Florhaug JA, Franklin J, Gottschall L, Hrovatin LA, Parker S, et al. A new approach to monitoring exercise training. J Strength Cond Res 2001;15: Gorostiaga EM, Izquierdo M, Ruesta M, Ibanez J. Effects of heavy resistance training on maximal and explosive force production, endurance and serum hormones in adolescent handball players. Eur J Appl Physiol 1999;80: Grodjinovsky A, Inbar O, Dotan R, Bar-Or O. Training effect on the anaerobic performance of children as measured by the Wingate anaerobic test. In: Berg K, Eriksson BG, editors. Children and exercise IX. Baltimore: University Park Press; p Hakkinen K, Mero A, Kauhanen H. Specificity of endurance, sprint and strength training on physical performance capacity in young athletes. J Sports Med Phys Fitness 1989;29: Hakkinen K. Changes in physical fitness profile in female basketball players during the competitive season including explosive type strength training. J Sports Med Phys Fitness 1993;33: Helgerud J, Engen LC, Wisloff U, Hoff J. Aerobic endurance training improves soccer performance. Med Sci Sports Exerc 2001;33: Hoff J, Helgerud J. Endurance and strength training for soccer players. Physiological considerations. Sports Med 2004;34: Hoffman JR, Maresh CM, Armstrong LE, Kraemer WJ. Effects of off-season and in-season resistance training programs on a collegiate male basketball team. J Hum Mus Perform 1991;1: Hoffman JR, Tenenbaum G, Maresh CM, Kraemer WJ. Relationship between athletic performance tests and playing time in elite college basketball players. J Strength Cond Res 1996;10: Hoffman JR, Epstein S, Einbinder M, Weinstein Y. A comparison between the Wingate anaerobic power test to both vertical jump and line drill tests in basketball players. J Strength Cond Res 2000;14: Hopkins DR, Shick J, Plack JJ, editors. Basketball for boys and girls: skills test manual. Reston: Alliance for Health, Physical Education, Recreation and Dance; Impellizzeri FM, Marcora SM, Castagna C, Reilly T, Sassi A, Iaia FM, et al. Physiological and performance effects of generic versus specific aerobic training in soccer players. Int J Sports Med 2006;27: Kraemer WJ, Koziris LP, Ratamess NA, Hakkinen K, Triplett- Mc Bride NT, Fry AC, et al. Detraining produces minimal changes in physical performance and hormonal variables in recreationally strength-trained men. J Strength Cond Res 2002;16: Laplaud D, Hug F, Menier R. Training-induced changes in aerobic aptitudes of professional basketball players. Int J Sports Med 2004;25:103 8.

10 88 G.C. Bogdanis et al. 27. Lucia A, Hoyos J, Perez M, Chicharro JL. Heart rate and performance parameters in elite cyclists: a longitudinal study. Med Sci Sports Exerc 2000;32: Matavulj D, Kukolj M, Ugarkovic D, Tihanyi J, Jaric S. Effects of plyometric training on jumping performance in junior basketball players. J Sports Med Phys Fitness 2001;41: Newton RU, Kraemer WJ, Hakkinen K. Effects of ballistic training on preseason preparation of elite volleyball players. Med Sci Sports Exerc 1999;31: Rotstein A, Dotan R, Bar-Or O. Effects of training on anaerobic threshold, maximal aerobic power and anaerobic performance of preadolescent boys. Int J Sports Med 1986;7: Rowland TW. Trainability of the cardiorespiratory system during childhood. Can J Sport Sci 1992;17: Siegler J, Gaskill S, Ruby B. Changes evaluated in soccerspecific power endurance either with or without a 10-week, in-season, intermittent, high-intensity protocol. J Strength Cond Res 2003;17: Wilder N, Gilders R, Hagerman F, Deivert RG. The effects of a 10-week, periodized, off-season resistance-training program and creatine supplementation among collegiate football players. J Strength Cond Res 2002;16: