Aprofessional basketball season imposes a great

PERFORMANCE CHANGES IN NBA BASKETBALL PLAYERS VARY IN STARTERS VS. NONSTARTERS OVER A COMPETITIVE SEASON ADAM M. GONZALEZ, 1 JAY R. HOFFMAN, 1 JOSEPH P. ROGOWSKI, 2 WILLIAM BURGOS, 2 EDWIN MANALO, 2 KEON WEISE, 2 MAREN S. FRAGALA, 1 AND JEFFREY R. STOUT 1 1 Sport and Exercise Science, University of Central Florida, Orlando, Florida; and 2 Orlando Magic Basketball Club, Orlando, Florida ABSTRACT Gonzalez, AM, Hoffman, JR, Rogowski, JP, Burgos, W, Manalo, E, Weise, K, Fragala, MS, and Stout, JR. Performance changes in NBA basketball players vary in starters vs. nonstarters over acompetitiveseason. J Strength Cond Res 27(3): 611 615, 2013 The purpose of this study was to compare starters (S) with nonstarters (NS), on ir ability to maintain strength, power, and quickness during a competitive National Basketball Association (NBA) season. Twelve NBA players were assessed at beginning and end of competitive season. However, because of trades and injury, only 7 (S = 4, NS = 3) players (28.2 6 3.4 years; 200.9 6 9.4 cm; 104.7 6 13.9 kg; 7.2 6 1.9% body fat) participated in both testing sessions and underwent analysis. Anthropometric performance (repetitive vertical jump power [VJP], squat power [SQT power], and reaction time) and subjective feelings of energy, focus, alertness, and fatigue were recorded during each testing session. Results were interpreted using magnitude-based statistics to make inferences on true differences between starters and nonstarters using unequal variances t-statistic. Starters played an average of 27.8 6 6.9 minutes per game and nonstarters played an average of 11.3 6 7.0 minutes per game. During course of season, changes in VJP indicated that starters were likely to increase VJP (Δ = 77.3 6 78.1 W) compared to nonstarters (Δ = 2160.0 6 151.0 W). There also appeared to be a possible beneficial effect on maintaining reaction time in starters (Δ = 0.005 6 0.074 seconds) compared with nonstarters (Δ = 0.047 6 0.073 seconds). In addition, no clear differences in DSQT power were seen between starters (Δ = 110.8 6 141.4 W) and nonstarters (Δ = 143.5 6 24.7 W). Changes in subjective feelings of energy indicated that starters were very likely to maintain ir energy over course of a season. It also appeared possible that Address correspondence to Dr. Jay R. Hoffman, jay.hoffman@ucf.edu. 27(3)/611 615 Ó 2013 National Strength and Conditioning Association starters were able to have a more positive response to subjective measures of fatigue and alertness than nonstarters, with only trivial differences between starters and nonstarters in regards to maintaining focus. Results of this study suggest that NBA players may enhance lower-body power, repetitive jump ability, and reaction during a competitive season, which appear to be enhanced with stimulus of playing time. KEY WORDS sport, overtraining, strength, reaction time, power INTRODUCTION Aprofessional basketball season imposes a great amount of physiological stress on athletes. The typical competitive National Basketball Association (NBA) season consists of 82 regular season competitions over a span of 5.5 months (2 5 games per week). In addition, athletes also play a month of preseason games and practice and potentially up to 2 months of a postseason. On top of games, players are also required to participate in daily or twice-a-day practice sessions in preparation for competition. The training stress incurred over long competitive NBA season may subject athletes to risk of overtraining syndrome if appropriate adjustments are not made to training programs. Overtraining symptoms are often noticed when an athlete is unable to fully recover from demands of a sport and often hinders athlete s ability to maintain optimal performance (4,19,20). Assessing sportspecific performance characteristics of professional basketball players during season may provide coaches and training staffs an ability to identify and make necessary adjustments to reduce risk for overtraining. There is limited research published pertaining to NBA athletes and ir demanding season. However, re have been several studies examining physiological changes during a season of competition in intercollegiate and European-level basketball players (2,8,16). Research has clearly indicated that basketball is predominantly an anaerobic sport (5,17), and several investigations on intercollegiate and European players have indicated that strength, power, agility, and speed can differentiate between different levels of VOLUME 27 NUMBER 3 MARCH 2013 611

Performance Changes in Basketball competition or predict playing time (3,11,14). Several studies have indicated that performance measures can be maintained during a season of competition (9,10), whereas ors have indicated that gains in strength can be achieved in previously untrained basketball players during a competitive season (8). However, none of se studies examined a season that was of similar length to that seen of an NBA team. Considering length of basketball season in NBA, those athletes who are part of regular rotation (starters) may experience a greater fatigue than those who are not playing consistently (nonstarters [NS]). Identification of players who experience decreases in performance may provide an opportunity for coach to make appropriate adjustments to ir training volume, training intensity, or even playing time to maximize potential as season progresses toward playoffs. Thus, purpose of this study was to compare starters (S) with nonstarters, on ability to maintain strength, power, and quickness during a competitive NBA season. METHODS Experimental Approach to Problem Professional basketball players on an NBA team performed strength, power, and agility assessments during a competitive basketball season. During each testing period, players also completed questionnaires regarding ir subjective feelings of energy, focus, fatigue, and alertness. These measures were part of a program designed to assess physiological stresses of a competitive NBA season. Testing began before start of regular season and concluded a week before end of regular season. Testing occurred every month, but only first and last testing periods were analyzed. All players participated in a regular weekly resistance training program during competitive season. The frequency of resistance training was dependent upon travel schedule, but players did lift between 8 12 times per month. To determine effect of playing time on performance changes, starters were compared with nonstarters. Subjects Twelve players under contract to play for NBA franchise Orlando Magic were assessed at beginning of competitive season. However, because of trades and injury, only 7 players (28.2 6 3.4 years; 200.9 6 9.4 cm; 104.7 6 13.9 kg; 7.2 6 1.9% body fat) participated in end of season testing. All analyses were performed with those players that participated in both pre- and postseason testing. All performance assessments were part of athlete s normal training routine. Players gave ir informed consent as part of ir requirements as a team member, which is consistent with policies of University s Institutional Review Board for use of human subjects in research. Performance Variables All athletes performed anthropometric (height, body mass, and body composition), repetitive vertical jump power (VJP), squat power (SQT power), quickness, and reaction time. In addition, during each testing session, subjective feelings of energy, focus, alertness, and fatigue were recorded. The order of testing was consistent for all testing sessions. Upon reporting to training facility, athletes dressed in ir normal practice uniforms and underwent anthropometric assessments, completed subjective questionnaires, and n performed vertical jump test, reaction test and concluded with squat test. Test-retest reliabilities for all assessments were R. 0.90. Total time played (total minutes), average minutes per game, games played, and games started were recorded from team s official statistics. Anthropometric Measures Anthropometric assessments included height, body mass, and percent body fat (%BF). Body mass was measured to nearest 0.1 kg. Body composition was assessed via skinfold analyses. Percent body fat was estimated via a 6-site skinfold test. The sites measured were triceps, scapula, chest, iliac crest, anterior thigh, and abdomen, using methodology previously described (13). Body density was calculated using equation of Jackson and Pollock (13), and %BF was calculated using equation of Siri (18). The same research assistant performed all skinfold assessments. Vertical Jump Power Each player performed five consecutive countermovement jumps. During each jump, players stood with ir hands on ir waist at all times and were instructed to maximize height of each jump while minimizing contact time with ground between jumps. Subjects wore a belt connected to a Tendo Power Output Unit (Tendo Sports Machines, Trencin, Slovak Republic). The velocity of each jump was calculated, and mean power output (VJP) for each repetition was recorded and used for subsequent analysis. Reaction Time Lower-body reaction time was measured with a 20-second reaction test on Quick Board (The Quick Board; LLC, Memphis, TN, USA) reaction timer. Subjects stood on a board of 5 circles, in a 2 3 1 3 2 pattern. Subjects straddled middle circle and reacted to a visual stimulus located on a display box that depicted 1 of 5 potential lights that corresponded with circles on board. Upon activation of light, subject attempted to move foot closest to circle that corresponded to visual stimulus. Upon a successful connection, next stimulus would appear. The total number of successful attempts for 20-second test and average time between activation of light and response to corresponding circle was recorded. Squat Power Power output during squat exercise was measured for each repetition with a Tendo Power Output Unit (Tendo Sports Machines,). The Tendo unit consists of a transducer attached to end of barbell, which measured linear displacement and time. Subsequently, bar velocity was 612

www.nsca.com TABLE 1. Magnitude-based inferences on anthropometric and performance changes during a season of competition in NBA starters vs. nonstarters.* S vs. NS Mean increase (%) Clinical inference % Beneficial/ positive % Negligible/ trivial % Harmful/ negative Body mass 1.3 Possibly 59.6 30.1 10.3 Body fat % 29.6 Possibly 57.6 30 12.4 VJP 17.15 Likely 94.5 4.8 0.8 Quickness 20.29 Unclear 33.3 30.6 36.1 Reaction time 25.66 Possibly 57.6 30 12.4 SQT power 23.28 Unclear 34 27.6 38.4 *NBA = National Basketball Association; S = starters; NS = nonstarters; VJP = vertical jump power; SQT = squat. calculated, and power was determined when barbell load was entered into microcomputer. The mean power output (SQT power) was recorded for each repetition and used for subsequent analysis. Test-retest reliability for Tendo unit in our laboratory has consistently shown R. 0.90. The squat test consisted of 2 sets of 5 repetitions at load approximating 80% of athlete s 1 repetition maximum in squat exercise. Subjective Measures of Energy, Focus, Alertness, and Fatigue Subjects were instructed to assess ir subjective feelings of energy, focus, fatigue, and alertness using a 15-cm visual analog scale (VAS). The scale was anchored by words low and high to represent extreme ratings where greater measured value represented greater feeling. Questions were structured as My level of energy is, My level of focus is, My level of alertness is, and My level of fatigue is. The VAS was assessed at each test date, and subjects were asked to rate ir feelings at that time by marking on corresponding line. The validity and reliability of VAS in assessing fatigue and energy has been previously established (15). Statistical Analyses The effects of NBA season were calculated as change from pre- to postseason measurements among starters and nonstarters. Magnitude-based inferential analyses were used as an alternative to normal parametric statistics to account for small sample size (n = 7). Several studies have supported magnitude-based inferences as a complementary statistical tool to null hyposis testing for reducing interpretation errors (1,12). The precision of magnitude inference was set at 90% confidence limits, using a p value derived from an unpaired t-test, and threshold values remained constant at 60.2 for small sample size. Inferences on true differences between starters and nonstarters were determined using unequal variances t-statistic on a published spreadsheet (1). Inferences were calculated on wher true population effect was substantially positive, negative, or trivial based on range of confidence Figure 1. Individual player scores in vertical jump power from beginning (pre) to end (post) of season. = NS; = S. NS = nonstarters; S = starters. Figure 2. Pre- to postseason changes in subjective measures of energy, fatigue, focus, and alertness. NS = nonstarters; S = starters. VOLUME 27 NUMBER 3 MARCH 2013 613

Performance Changes in Basketball TABLE 2. Magnitude-based inferences on changes in subjective measures of energy, focus, fatigue, and alertness during a season of competition in NBA starters vs. nonstarters.* S vs. NS Mean increase (%) Clinical inference % Beneficial/ positive % Negligible/ trivial % Harmful/ negative Energy 214.28 Very unlikely 22.8 31.1 46.1 Fatigue 227.04 Possibly 67.2 24.7 8.1 Focus 1.17 Unlikely 30.4 43.9 25.7 Alertness 8.44 Possibly 48.4 34.4 17.2 *NBA = National Basketball Association; S = starters; NS = nonstarters; VJP = vertical jump power; SQT = squat. interval relative to value for smallest clinical worthwhile effect. If likely range substantially overlaps both positive and negative values, it is inferred that outcome is unclear. The chance that effect was positive or negative was evaluated by following scale:,1%, almost certainly not; 1 5%, very unlikely; 5 25%, unlikely; 25 75%, possible; 75 95%, likely; 95 99% very likely; and.99% almost certain (12). Results were interpreted using magnitude-based statistics and reported as mean 6 SD. RESULTS Starters (n = 4) played an average of 1813 6 639 total minutes (27.8 6 6.9 minutes per game) and nonstarters (n =3)played an average of 543 6 375 total minutes (11.3 6 7.0 minutes per game) over competitive season. Evaluation of magnitude inferences indicated a very likely difference in playing time between starters and nonstarters. Magnitude-based inferences on changes in performance and anthropometric measures are depicted in Table 1. During season, it appeared possible that starters maintained ir body mass (0.5 6 1.2 kg), whereas nonstarters lost ir body mass (20.9 6 3.1 kg). Magnitudebased inferences on Dchange in body composition indicated a possible beneficial effect of starters (0.025 6 1.389%) on maintaining %BF compared with starters (0.833 6 1.443%). The Dchanges in VJP indicated that starters were likely to increase VJP (77.3 6 78.1 W) compared with nonstarters (2160.0 6 151.0 W). Examining individual responses of each player revealed that 3 of 4 players who are starters increased VJP, whereas all 3 players who are nonstarters decreased VJP during season (see Figure 1). Magnitudebased inferences indicated that a competitive NBA season had a possible beneficial effect on maintaining reaction time in starters (0.005 6 0.074 seconds) compared with nonstarters (0.047 6 0.073 seconds). In addition, re appeared to be no clear difference in DSQT power between starters (110.8 6 141.4 W) and v (143.5 6 24.7 W). Interestingly, all players (both starters and nonstarters) increased SQT power during course of basketball season. Pre- to postseason changes in subjective measures of energy, fatigue, focus, and alertness can be observed in Figure 2. Magnitude-based inferences on se changes can be seen in Table 2. Changes in subjective feelings of energy indicated that ability of starters to maintain ir energy was very unlikely over course of a season. It also appeared possible that starters were able to have a more positive response to subjective measures of fatigue and alertness than nonstarters. There appeared to be trivial differences between starters and nonstarters in regards to ability to maintain focus. DISCUSSION The NBA season is a long arduous event that may pose a significant limitation to athlete s ability to maintain performance levels. Although all players on roster practice and travel, athlete s who are part of coaches regular playing rotation (get in game on a consistent basis for extended period of time) may experience greater levels of fatigue and risk experiencing performance decrements if appropriate rest and recovery are not achieved (4,19). However, to our knowledge, this is first study to attempt to quantify magnitude of performance changes during an NBA basketball season. The results of this study indicated that starters were not only able to maintain ir physical performance levels throughout season but greater playing time appeared to have provided a greater stimulus for enhancing VJP. In addition, starters appeared to maintain ir body composition and reaction time better than nonstarters. Greater playing time also appeared to have positive effects on feelings of fatigue and alertness, whereas only detriment associated with starters was a possible decrease in energy as season progressed. The team was successful as reflected by a 52 to 30 regular season record and made playoffs, but lost in first round. The measures used to assess performance changes in this study were consistent with what has been recommended for basketball players (5,9,17). Basketball is predominately an anaerobic sport (5,7,11,17), and studies have shown that lower-body strength and power performance are indicators of playing time in basketball players (11). As such, it appears imperative that strength and power measures should be maintained during a season. Interestingly, previous studies have demonstrated that this is attainable in National Collegiate Athletic Association Division I basketball players, as 614

www.nsca.com long as se players continue to lift through season (8,10). Furrmore, strength gains can be achieved during season, especially in novice or less experienced athletes (10). However, in contrast to collegiate basketball season, NBA season is nearly twice as long, possibly potentiating a greater cumulative fatigue in NBA athlete. Despite this concern, results of this study provide additional support for in-season strength and power improvements in NBA athletes. It appears that greater playing time acts as a stimulus for enhancing jump power performance. All players were required to perform a repetitive 5-jump test. This was intended to mimic repetitive jumping experienced by players fighting for rebounds during a game. The greater jump power performance seen in starters compared with nonstarters suggests that additional playing time, or intensity of jumps performed in an NBA game, provides a greater stimulus for eliciting improved repeated jump performance. This likely contributed to greater reaction time observed in starters as well. Or investigators examining European basketball athletes participating in longer competitive season than collegiate athletes, but less than NBA athletes, have reported that anabolic/catabolic balance is maintained during season (16). This suggests that physiological stress associated with that specific competitive scenario was well tolerated by those athletes. Although we did not measure hormonal changes, performance results of this study do suggest that athletes were able to withstand rigors of NBA season. Still, fatigue can manifest itself in several different ways (4). Considering that energy levels were more affected in starters than nonstarters suggests that some negative results were seen toward end of season. Although speculative, we may have started to see initial signs of an overtraining syndrome. Interestingly, fatigue appeared to manifest itself to a greater extent in nonstarters than starters. This may be related to dissatisfaction associated with insufficient playing time. A previous study has shown that mood of professional basketball players, especially fatigue and tension, is influenced by personal factors related to athlete s relationship to coach or team administrators (6). PRACTICAL APPLICATIONS The importance of monitoring elite basketball players performance for overtraining is crucial not only to athletes but also success of teams. However, it is important to acknowledge that each athlete responds individually to stresses of practice and games. Although results of team may be consistent, it is important for strength and conditioning coach to examine individual player performance as well. When needed, specific adjustments to athlete s daily routine (i.e., greater recovery, less time on court) may prevent potential performance decrements that may not manifest as part of team results. 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