Basketball is considered an intermittent high-intensity sport that requires a well-developed physical fitness to be successfully played (32). Authors consider lower-limbs explosive power (20,21) and aerobic fitness (41) as main factors in basketball physical performance and training. Specifically, a good level of lower-limbs explosive power is considered useful to perform powerful accelerations and winning jumps during the game (21-23). This is of particular interest to game outcome because most scoring attempts develop very rapidly during the game (32).
In male professional basketball competitions (32), players perform as many as 46 ± 12 jumps, with sprinting over short periods of time (1-2 s) for 105 ± 52 times. Furthermore, vertical-jump height was related to playing time in elite collegiate basketball (23).
Although from a physiologic standpoint, there is consensus indicating basketball as a predominantly anaerobic game, maximal aerobic power is routinely assessed in elite basketball players (41). Nevertheless, the effect of maximal aerobic power on basketball performance is not well understood, and normative data are not evidence based (24). However, recently, Ben Abdelkrim et al. (9) showed that estimated maximal oxygen uptake (O2max) was positively related with live time spent at high intensity during the game in Under-19 basketball players. Furthermore, Narazaki et al. (35), using direct assessment of oxygen uptake during practice sessions, showed that, in professional players, the aerobic contribution to performance was higher than previously estimated.
The aerobic and anaerobic performance of basketball players competing at the elite level was examined in several studies (1,21). However, to the best of the present authors' knowledge, no study has addressed the aerobic and anaerobic performance abilities of nonelite-level basketball players such as those competing at a regional level. Data on this selected population of players would be of great interest because there are many players, coaches, and fitness trainers involved in these competitive contexts (1).
Therefore, the aim of this study was to examine the aerobic and explosive-power performance of experienced regional-level basketball players of different competitive levels. This is to gain information for training prescription and talent selection. A working hypothesis assumed the existence of competitive-level physical performance differences in regional-level basketball players.
Experimental Approach to the Problem
The physical demands of the game can be obtained by analyzing match activities, making relevant measurements during the match, and assessing the physiologic status of successful players (4,32,33,45). Consequently, the information gained on successful basketball teams may be of interest for training prescription and talent selection (45).
In this study, we adopted a descriptive, stratified, cross-sectional design to examine the physical performance (i.e., aerobic fitness and lower-limbs explosive power) and characteristics of players competing at the regional level. As a cross-sectional paradigm, we considered 2 basketball teams that, at the time of this study, had won their relative (senior [S] and junior [J] level) championships after playoff tournaments. Group analyses were performed to detect possible sport-specific and competitive level-related information to be used in regional-level basketball training.
Recent studies have shown that, when comparing athletes of different body size, the scaled O2max notation (i.e., mL·kg−0.75·min−1) is preferred (15). This is of particular interest in basketball because players competing either at elite or subelite levels are reported to be a nonhomogenous population in terms of body size and dimensions (2). Consequently, relative and scaled notations were used to express players' O2max.
Twenty-two basketball players who, during the 2002 to 2003 season, belonged to a regional level amateur basketball club (Adriatica Basket, Porto Recanati, Macerata, Italy) volunteered for this study (Table 1). Eleven players were active team members of the 6th division team (Series C2, Italian higher senior regional competitive-level[S]) that ranked first during the 2002 to 2003 regular season (with 14 points lead), gaining access to the higher division (C1, Italian Senior Inter-regional Championship) after winning playoff finals. At the time of this investigation, S was the first team that ever won 34 of 36 regular-season games in the 6th division basketball championship of the Marche region (Italy). The remaining 11 players were members of a junior basketball team (J) of the same S club who won, during 2002 to 2003 season, their regional junior-division championship.
The study cohort was composed of 3 playmakers, 3 centers, 3 guards, and 2 wings for the S and J groups. Players were active team members and regularly played during the championship games.
Senior and J players trained 4 times a week (approximately 90 min per session), with a competition usually taking place during the weekend. The training schedules followed by S and J were similar to the usual training week undertaken by an average basketball team competing at the regional level. The overall weekly training volume included 90 minutes for strength and conditioning (3 × 30 min sessions of plyometrics and sprint training), 330 minutes for technical-tactical training, 90 minutes for a training game, and 90 minutes for a championship game. Training load increased progressively from Monday to Wednesday and decreased afterward, with Friday as a tapering day.
All players had at least 10 years of experience in competitive basketball. The playing experience in the category of appurtenance was of 3 ± 1 and 4 ± 2 years for the J and S players, respectively. Physiologic measurements were taken either for S and J approximately 2 weeks before the beginning of the playoff tournament when coaches believed that their teams were at their top competitive performance.
All players had official medical clearance according to national law. Written informed consent was received from all players and parents after a detailed verbal and written explanation of the experimental design and potential risks of the study. Maximal effort was solicited during all the testing procedures.
Subjects were told to refrain from heavy training, alcohol, caffeine, and tobacco use for the 2 days preceding testing sessions. During the 2 hours preceding the testing sessions, only as desired water was allowed, and subjects consumed a light meal at least 3 hours before the beginning of exercise. All players were familiar with the testing procedure used before the start of this study. Players were told they were free to withdraw from the study at any time without penalty. The study was approved by an independent institutional review board according to the Guidelines and Recommendations for European Ethics Committees by the European Forum for Good Clinical Practice.
Explosive power was assessed using the testing procedures developed by Bosco et al. (11). Each player was assessed for vertical-jump height during countermovement (CMJ) and stiff-leg jumping (SL). According to Bosco et al. (11), vertical-jumps height is assessed by fly time (FT) record using a switch mat connected to a laptop computer (Muscle Lab, Bosco System, Rome, Italy). During CMJ and SL testing, subjects were free to swing their arms during jumping. Subjects performed 3 CMJ jumps (90° knee flexion) with at least 1 minute of recovery between trials. The best measure was assumed as indication of knee extensor explosive power.
Stiff-leg jump testing consisted of 5 jumps continuously performed over the switch mat with each jump assessed for FT and contact time (CT) (11). The best FT versus CT ratio was considered as representative of lower-leg explosive power (47).
The ratio between each player' best SL and CMJ heights was used to evaluate lower-limbs explosive-power balance (RB) with the following formula: RB = [SL/CMJ]*100 (31). Reliability of the test variables used in this study calculated as intraclass correlation coefficient and coefficient of variation were assessed before the start of this study as a standard quality assessment procedure and ranged between 0.95 and 0.98 and 1-1.2%, respectively.
Maximal cardiorespiratory values of S and J players were determined using an exercise mode-specific progressive multistage field test (yo-yo endurance test [Yo-Yo]) (5,30,40) that has been proven to elicit peak physiologic responses not significantly different from those achieved in laboratory conditions (8,27,29,40). Yo-Yo was performed over the wooden basketball court usually used by S and J for practice and competitions.
During the Yo-Yo, the subject wore a light-weight breath-by-breath portable gas analyzer (K4b2, COSMED, Rome, Italy). Validity and reliability of the K4b2 portable gas analyzer have been reported elsewhere (17). The physiologic profiles of the variables of interest were monitored by telemetry. Data were stored in a laptop computer (Texas Instruments, Extensa 501T, Dallas, TX, USA) for post hoc analyses using dedicated software (K4b2, 7.1 version, COSMED, Rome, Italy).
The highest heart rate achieved at exhaustion was considered as representative of the individual maximal heart rate (28,44). Maximal oxygen uptake was considered as the mean of O2 values detected during the last 15 seconds of exercise. All players were able to meet at least 2 of the following criteria at exhaustion: heart rates higher than the 210-age formula, respiratory exchange ratio higher than 1.1, and a levelling off of O2 despite Yo-Yo speed increase.
Standard anthropometric variables (stature, body mass and triceps, subscapular, supraspinal, abdominal, front thigh and medial calf skinfolds) were obtained for all subjects by a trained anthropometrist following methods suggested by the International Society for the Advancement of Kinanthropometry (18). Anthropometric instruments used in this study included a stadiometer, scale (Rabonne Chesterman, Silverflex, United Kingdom), and skinfold calliper (Holtain, Ltd., Crymych, United Kingdom). Percentage of body fat was estimated according to Carter's equation (12).
All measurements were carried out on the same day. Vertical jumping was performed before Yo-Yo test. At least 20 minutes of recovery were allowed to players before the start of Yo-Yo test.
Before each test, subjects were told to perform a self-paced and self-administrated warm-up consisting of 5 to 10 minutes of jogging followed by 5 minutes of gentle dynamic stretching (16). Subjects were allowed 2 to 3 minutes of jump practice before explosive-power testing. A brief pretest familiarization was allowed to players after wearing of a K4b2 gas analyzer that consisted of 4 × 20 m shuttle running at Yo-Yo first-stage speed (8 km·h−1) (6). Assessments took place at a time corresponding to the usual training session performed by S and J players (5-8 pm). Before each test, the K4b2 gas analyzer was calibrated according to the manufacturer's guidance (COSMED K4b2 user manual, Rome, Italy).
Means and SD were calculated for each variable. The relationship between variables of interest were tested using Pearson' product-moment correlation coefficients. Intergroup comparisons were performed using unpaired t-tests. Linear regression analysis was performed to calculate the allometric equation b exponent (15). Significance was set at p ≤ 0.05 a priori. A trend was defined as being between 0.10 and the alpha level. Statistical analyses were performed using the Statistica package (Version 6.01, Statsoft, Tulsa, OK USA).
Anthropometric characteristics and jumping performances of S and J players are shown in Tables 1 and 2, respectively. Exercise mode-specific O2max values were 60.9 ± 6.26 and 50.3 ± 3.98 mL·kg−1·min−1 for S and J, respectively. Senior team O2max value was significantly different from J (p = 0.001), either expressed as relative (i.e., mL·kg−1·min−1) or scaled (mL·kg−0.75 ·min−1) values. There was a significant inverse correlation between body mass and O2max expressed as mL·kg−1·min−1, confirming that, when using this notation, heavier subjects' O2max were underestimated (r = −0.68, p = 0.003). Absolute O2max revealed to be proportional to body mass (r = 0.53, p = 0.03). Log-log linear regression analysis showed a b exponent of 0.41 (r = 0.53, p < 0.05).
No significant difference between Yo-Yo test performance (distance covered) was observed between S and J groups (2,055 ± 267 and 2,020 ± 174 m, respectively, p > 0.05). Yo-Yo performance was not able to predict actual O2max (r = 0.43, p = 0.08). Actual O2max values were significantly higher than the values calculated using the Ramsbottom et al. (40) distance over O2 conversion table (55.3 ± 7.39 vs. 50.7 ± 3.34 mL·kg−1·min−1, p = 0.045).
Because running endurance performance has been reported to be affected by lower-limbs explosive-power status (36-38), we analyzed the possible relationship occurring between selected explosive-power variables and Yo-Yo performance. Analyses (pooled data, n = 22) revealed that distance covered during Yo-Yo test was positively related to RB (r = 0.62, p = 0.01). A positive trend was detected between Yo-Yo distance covered and SL/CT (r = 0.48, p = 0.06).
In this study, we were able to assess the aerobic fitness and explosive-power performance of 2 successful basketball teams competing at the regional level. Results showed that to compete successfully in regional-level adult basketball, player's aerobic fitness should not be regarded as a limiting factor. In fact, S players showed significantly lower O2max values compared with the J counterpart. This finding is in accordance with Hoffman et al. (23), who showed no relationship between aerobic-fitness level and seasonal playing time. Maximal oxygen uptake values of S players are similar to those reported by other authors for American and Finnish professional basketball players (19,39) but lower than the average value found by McInnes et al. (32) in professional Australian players.
On the other hand, J players' O2max was in line with what was previously reported by other researchers for young male collegiate basketball players (42). However, Hunter et al. (25) found in intercollegiate players (age, 18-22 yr) average O2max levels of 50 ± 7.7 mL·kg−1·min−1.
Maximal aerobic power values around 50 mL·kg−1·min−1 were reported also by Hunter and Hilyer (24) and Balonchuk et al. (3) in other college players. Hoffman et al. (22) reported for elite-level Israeli youth basketball players an average O2max level of 50.2 ± 3.8 mL·kg−1·min−1.
This confirms the assumption that players may play successful basketball in their respective divisions with O2max levels not lower than 50 mL·kg−1·min−1 (23). Whether a higher O2max may be of help to basketball players is currently not well understood because researchers have reported conflicting results. Hoffman et al. (23) found that playing time was inversely related to endurance assessed with 2.414 m time trial run test. The average estimated O2max in the Hoffman and Maresh (21) study was higher than 50 ml·kg−1·min−1. More recently, Ben Abdelkrim et al. (9) found a moderate (r = 0.55, p < 0.05) although significant relationship between time spent in high-intensity activities during live-time and estimated O2max in Under-19 basketball players. Direct assessment of oxygen uptake during friendly games showed that the aerobic contribution to basketball performance was higher than previously estimated in professional players (35).
Although some investigations have reported a significant effect of O2max and aerobic fitness in enhancing postmaximal-intensity exercise recovery (43), basketball studies showed that O2max has a limited if any effect in promoting basketball-specific sprint performance maintenance (14,22). However, the available research has addressed exercise bouts of 6 to 30 seconds performed over a period of approximately 6 minutes (22). This is an exercise duration much shorter than the 40 minutes live time normally considered for a basketball game, in which sprints on average last between 1 to 2 seconds (32). Therefore, the role of the oxidative metabolism might increase as the game playing time progresses (22). The correlation between aerobic capacity and activity level recently reported suggests the potential benefit of aerobic conditioning in basketball (9,35). In this regard, training studies are warranted to assess the effect of O2max improvement on actual match play in basketball (26).
In this study, we verified that, according to scaling theory, O2max expressed as mL·kg−1·min−1 underestimated heavier players. However, log-log plots of absolute O2max versus body mass gave a reduction exponent quite different from those reported in other studies (10,15,45). In expressing O2max using this study's b exponent (b = 0.41), no significant difference was found between S and J maximal aerobic power.
This question of the applicability of the standard notation of O2max (i.e., mL·kg−1·min−1) arises when dealing with populations with important differences in body dimensions, as is usually found in basketball players. Although no conclusive inference may be drawn because of the limited number of subjects considered in this study, further investigation should be performed to address the issue of scaling in basketball players. Information about scaling is of great interest when comparing subjects of different ages, an issue that has a tremendous impact in talent selection and training prescription (15,45).
Interestingly, S players, although possessing a lower O2max, were able to cover the same distance running back and forth on the basketball court at progressive speeds (i.e., Yo-Yo test).
Explosive-power level was shown to have a role in Yo-Yo performance because group correlations showed that the ability to rapidly shift from eccentric to concentric contraction regimes was related to the total distance covered. Specifically, the calves' explosive power was correlated with distance covered during Yo-Yo test. This is supported by a trend between SL/CT and Yo-Yo distance and a significant relationship of the latter variable with RB. These findings coupled with a significantly higher SL/CT ratio in S may explain similar Yo-Yo performances between groups.
This could mean that to improve high-intensity specific running performance in basketball players, coaches and fitness trainers should pay attention to the calves' reactive/explosive power.
However, with this study design, no inference can be drawn as to what extent a better lower-leg explosivepower will be beneficial to actual game play. In this regard, physiologic assessments coupled with sound match analyses may shed light on this interesting issue.
In light of these study findings, the Yo-Yo test may be considered as a good field test by which to assess the gross ability to exercise economically on the court in basketball players. However, Yo-Yo was not related to O2max, and the proposed distance versus O2 conversion table suggested by Ramsbottom et al. (40) was revealed to be invalid with this selected population of basketball players. As a consequence, coaches and fitness trainers should only use distance covered as a Yo-Yo performance variable. These results are in contrast with other studies that found a significant correlation between Yo-Yo distance and O2max in nonelite soccer players (13,44), suggesting specific population validity.
These findings have a considerable importance in basketball because this kind of continuous progressive shuttle-running test over 20 m is extensively used in basketball for aerobic fitness assessment (41). However, other maneuvers than running are performed by basketball players during the game (32).
Knee extensor explosive power was not different between S and J. Nevertheless, players of the S group were shown to possess a higher level of lower-leg explosive power, as shown by the significantly higher SL/CT ratio. This finding suggests that lower-leg reactive/explosive power might be considered a discriminative variable in amateur regional level basketball players.
The practical importance of this finding should be accurately examined by considering basketball studies that focused on neuromuscular performance. Moreno (34) suggested that explosive power and reactivity are components of quickness and should be considered because of the players' ability to suddenly change court-activity during the game. Although quickness is a complex ability (34), shorter ground contact times during explosive actions may have a positive influence on quickness (7,46). This is an issue of great interest for the development of the basketball conditioning science, and we believe it is worth studying with proper research designs.
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