An study of a professional basketball team (FC Barcelona) was conducted over four seasons. The team played four main competitions every season: the Spanish Super Cup, the Spanish League (ACB), the King's Cup, and the Euroleague. The data were collected from 2010–11 to 2013–14. Players were examined at the beginning of each season using the FC Barcelona (FCB) periodic health examination protocol, consisting of a medical history and physical examination, anthropometry, spirometry, basal 12-lead ECG, submaximal cardiovascular exercise testing (with ECG and blood pressure monitoring), and echocardiography. The medical team was composed of one sports physician (GR) who was responsible for the health care of all players in the team on a day-to-day basis. Supplementary imaging studies or specific rehabilitation treatment required were provided by FCB Medical Services. The S&C coach (TC) recorded all strength, conditioning, and performance data. The data were recorded daily after every practice and game. All the participants had taken part in another retrospective study previously published.20

Thirty male professional basketball players (age, 27.6 ± 4.1 years; height, 200.1 ± 9.4 cm; weight, 98.5 ± 12.6 kg) from the FC Barcelona professional basketball team participated in the study over four consecutive seasons. Each player was enrolled on the team for 1.7 ± 0.98 seasons during this period. Of the players involved, 23 were Caucasian and 7 were African American; 18 originated from Europe, 8 from North America, 1 from South America, 2 from Oceania and 1 from Africa. The inclusion criteria for all subjects required that each participant was part of the FC Barcelona professional team roster for at least a complete season, was aged over 18 years, was not involved in a time-loss injury rehabilitation process and had had all three blood tests. During the study, 14 of the 44 initial participants were unable to meet the inclusion criteria. All the players and the team were informed of the risks and benefits of the study and gave written informed consent to participate in it. Players were allowed to refuse the inclusion of their data. The study was conducted following the ethical principles for biomedical research with human beings established in the Declaration of Helsinki of the World Medical Association (amended in 2013). It was approved by the club's Board of Directors and by the Ethics Committee of the Catalan Sports Council, Spain (favorable reports are available upon request).

The duration of each season was 42 ± 4 weeks. Workload planning, both conditional and technical/tactical, was designed with as similar a structure as possible between mesocycles, with a duration of 6 ± 1 weeks. Mesocycle periodization followed the block periodization model.21 According to the schedule of games and main competitions, the seasons were divided into 7 training periods (mesocycles), each made up of 6.16 ± 0.76 planning units (microcycles). They were distributed as follows: Monday was normally a day off or for individual recovery and technical drills; Tuesday morning: strength workout (1 h 15 min to 1 h 30 min) and technical drills (30 to 45 min); Tuesday afternoon: tactical practice (1 h 30 min to 2 h); Wednesday afternoon: tactical practice (1 h 30 min to 2 h); Thursday: technical drills and tactical walkthrough (1 h 15 min); Thursday night: game; Friday afternoon: recovery and metabolic workouts (1 h) plus half-court tactical practice (30 min); Saturday morning: tactical practice (1 h 30 min to 2 h).

Each season was divided into seven mesocycles, always considering the competition schedule. The Spanish Super Cup was played during the first mesocycle. The second mesocycle focused on the start of the regular season of the Spanish League (ACB) and the Euroleague (European championship). Most of the first phase of the regular competitions took place during the third mesocycle. The fourth mesocycle included the King's Cup. The fifth mesocycle covered the second phase of the regular competitions and the Euroleague playoffs. The sixth mesocycle ended with the Euroleague Final Four, and the seventh mesocycle comprised the Spanish League (ACB) playoffs (see Fig. 1).

Fig. 1.

Basketball team season periodization by mesocycles, blood analysis schedule during the four seasons of the study and team performance outcomes (adapted from Caparrós et al., 2022).

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Team workload was expressed as the sum of the exposure time (EXP) of individual players to practice (EXPp) and competitions (EXPc). Exposure was measured as both number and hours (h) of games and number and hours of total practice sessions.22 It was counted from the start of the season until the first injury or the end of follow-up (end of season) for players who were not injured. Game time was defined as the number of hours that each player spent playing competitive games, and practice time refers to specific team practice on court, conditioning, and injury prevention workouts.

Blood analyses were performed at the beginning of the preseason (first microcycle) and at the beginning of the third and fifth mesocycles. This periodization made it possible to obtain individual data before the main competitions that had to be played, so that there was time to adjust training loads if it was considered necessary.23 Two ml of blood was obtained, during the morning and in fasted state 48 h after the last training session. The procedure was standard venipuncture of the antecubital vein using a Vacutainer tube, centrifuging the sample at 2000 x g at 4 ºC for 10 min to obtain serum. The serum was stored at −80 ºC for later analysis.

The sandwich ELISA was carried out as follows. Monoclonal anti-myosin fast and slow antibodies were coated onto a polystyrene plate. The calibration curve was generated with 6 different concentrations (from 0 to 250 ng) of purified pork myosin. Ten microliters of each serum sample was loaded in triplicate into the wells of the plate. The plates were incubated and stirred at 37 °C for 1 h and then washed 3 times with PBS wash and incubated at room temperature with 50 µl of TMB substrate for the luminescent reaction of the peroxidase. The reaction was stopped with 50 µl of 2 M H2SO4, and the plates’ absorbance was read at a wavelength of 450 nm.19

To analyze muscle response and determine which types of fibers were most involved during the season, we evaluated FM (G6 95% CI = 0.92–0.97; CV 95% CI = 0.76–0.81) and SM (G6 95% CI = 0.92–0.96; CV 95% CI = 0.53–0.83) in serum for the three blood samples18 according to the players’ individual workload and performance, or ranking (RKG), just two weeks before the sample was taken.19

The following materials were used: monoclonal anti-myosin fast antibody (Sigma M1570); monoclonal anti-myosin slow antibody (Sigma M8421); purified porcine myosin (Sigma M0273); polyclonal rabbit antibody (Sigma M7523); anti-anti rabbit antibody linked to peroxidase (Sigma A6154); SuperBlock blocking buffer (Thermo Scientific 37515); PBS Tween 20 (Sigma P7949); TMB peroxidase substrate (Sigma T0440); polystyrene plate (Corning 3591). Reagents: K2HPO4 (Merck 105,104), KH2PO4 (Merck 4873), NaCl (Merck 106404), H2SO4 (Merck 100731).

The team's performance outcomes were the number of competitions won out of the four played during the season: Spanish Super Cup, King's Cup, Spanish League and Euroleague. Team and individual performance is assessed by the official game statistics for both the team and the individual players: total ranking (RKG) by season and by game, and presented as arbitrary units (a.u). At the end of each game, for each player, the official RKG quantified PS, missed shots (MS: 2 points, 3 points and free throws), total rebounds (REB) (offensive plus defensive), assists (AST), steals (STL), turnovers (TOV), blocks received (BLKA), blocks made (BLK, personal fouls committed (PF), and personal fouls received (PFR). From these values a positive or negative ranking number is obtained based on the following formula: RKG = (PTS + REB + AST + STL + BLK + PFR) − (MS + TOV + BLKA + PF).20

Data are presented as mean ± standard deviation (SD). Initially, a central tendency descriptive study was performed. According to the size of the sample, intrasession reliability of measures was determined using Guttman's Lambda 6 test24 with 95% confidence intervals. The normality of each variable was determined by the Shapiro-Wilk test. With the average team values for the workload variable and the SM and FM serum-level variables for each blood sample, with regard to the normality of the variables, a one-way ANOVA was performed to determine their possible independence during the various seasons and samplings. When any significant main effects were found, pairwise t-test comparisons with a Tukey correction were used. Effect size (ES) (Cohen d) was calculated to determine the practical difference between baseline values and serum peaks. ES values of over 0.8, 0.8 to 0.5, 0.5 to 0.2, and lower than 0.2 were considered large, moderate, small, and trivial respectively. The results were weighted to take account of the number of players in each blood analysis. Subsequently, and with regard to the non-normality of the sample, a Spearman correlation coefficient was employed to evaluate the possible association between the individual values relative to the difference in the SM and FM percentage serum levels between the different blood samples and the workload variables. The coefficient values were between −1 and +1 in all cases. The correlation magnitude was defined according to Hopkins's criteria:25 random: 0–.09; low: 0.10–.29; moderate: 0.30–.49; large: 0.50–.69; very large: 0.70–.89; nearly perfect: 0.90–.99; perfect. Finally, multiple linear regressions were performed and the causal relationship between the average values per season and the SM and FM serum levels was explored. The statistical analysis was carried out using the JASP program version 0.11.1.0 for Windows 10 (JASP Team, Amsterdam, The Netherlands). The level of significance in all cases was p < .05.

During the four seasons and up to the third blood analysis, the team played an average of 46 ± 7 games and had an EXP to practice of 280.17 ± 58.1 h during 156.1 ± 32.9 sessions per season. With regard to the results per season, the lowest workload values occurred during the first mesocycle (between 5.25 ± 0 and 10 ± 0 h EXP), except in the 2011–12 season (with 34.54 ± 6.34 h EXP), increasing in the third mesocycle (except in the 2011–12 and 2012–13 seasons), and decreasing, relative to the maximum values, in the fifth mesocycle (except in the 2012–13 season).

The following average values per season were obtained: 1835.33 ± 848.97 µl mol/L for FM and 985.33 ± 896.19 µl mol/L for SM in 2010–11; 1369 ± 715.79 µl mol/L for FM and 1084.33 ± 208.56 µl mol/L for SM in 2011–12; 858.4 ± 279.15 µl mol/L for FM and 1700.25 ± 507.92 µl mol/L for SM in 2012–13, and 1786.66 ± 290.97 µl mol/L for FM and 1746±210.65 µl mol/L for SM in 2013–14.

Assessing the results according to when the analysis was performed, the period analysed showed average results for FM that were highest in the first mesocycle (1610 µl mol/L) and lowest in the fifth (1027 µl mol/L), and for SM they were highest in the first mesocycle (1395 µl mol/L) and lowest in the third (1222 µl mol/L) (see Table 1). By season, the highest levels of FM and SM were observed in all cases during the first mesocycle of each season, with the highest values in 2010–11 (2807.23 ± 972.22 and 2020.3 ± 835.57 µl mol/L respectively), and the lowest, also in both cases, in the 2011–12 season (545.99 ± 442.21 µl mol/L for FM and 1318.56 ± 308.71 µl mol/L for SM) (see Table 1).

Table 1.

Mean values ± SD of workload and fast and slow myosins by season and blood analysis during 4 seasons in a professional basketball team.

EXP: Exposure time; EXPp: exposure time to practice; EXPc: exposure time to competition, FM: Fast myonisn; SL:Slow myosin's; F/S: ratio fast myosin slow myosin serum; µl mol/L:nanoliter by mol; h: hours; a.u: arbitrary units.

Statistically, the one-way ANOVA test only showed significant differences between each of the blood analyses for FM and SM per season (F = 7.03; df = 3; p < .05). The post hoc analysis made it possible to observe differences between the 2010–11 season and the 2012–13 (p = .01; d = 2.18; Cohen's d = 3.3) and 2013–14 (p < .05; d = 1.71; Cohen's d = 2.57) seasons.

Spearman did enable us to assess the following possible relationships between workload and SM and FM concentrations. With regard to exposure, very strong negative relationships could be observed between SM and EXP (rho= −.63; p = .02) and EXPp (rho= −.63; p = .02), as well as between FM and EXPc (rho = −.69; p = .01).

Regarding performance outcomes, during the period analysed team total season RKG was 6879.5 ± 985.37 a.u.; mean team RKG per game was 90.72 ± 2.79 a.u. . Team RKG per game was 88.19 ± 14.96a.u. for the 2010–11 season, 88.9 ± 18.19 a.u. for 2011–12, 92.75 ± 20.00 a.u. for 2012–13, and 93.84 ± 20.94 a.u. for 2013–14. By player and game, RKG values were 9.4 ± 2.51 a.u. for 2010–11, 8.4 ± 2.33 a.u. for 2011–12, 7.53 ± 0.68 a.u. for 2012–13, and 7.1 ± 2.42 a.u. for 2013–14. The team won 7 competitions (3 Spanish Championships, 2 King's Cups, 2 Spanish Super Cups) and achieved a European top four qualification (Final Four) on 3 occasions: 2010–11 (King's Cup, Spanish Championship and Spanish Super Cup), 2011–12 (Final Four, Spanish Championship and Spanish Super Cup), 2012–13 (Final Four, King's Cup) and 2013–14 (Final Four, Spanish Championship).

A multiple regression analysis showed possible associations between SM, as an independent variable, and performance outcomes: player mean RKG per game and season (R = 0.99; R2 = 0.98; adjusted R2 = 0.97; p < .01) and the team performance outcomes achieved (R = 0.91; R2 = 0.83; adjusted R2 = 0.75; p = .01) during these four seasons.