Impact of Exercise-Induced Muscle Damage on Performance Test Outcomes in Elite Female Basketball Players

Abstract

Doma, K, Leicht, A, Sinclair, W, Schumann, M, Damas, F, Burt, D, and Woods, C. Impact of exercise-induced muscle damage on performance test outcomes in elite female basketball players. J Strength Cond Res 32(6): 1731–1738, 2018—The purpose of this study was 2-fold: first, to examine the impact of exercise-induced muscle damage (EIMD) on physical fitness qualities after a basketball-specific training session; second, to determine the reproducibility of the sport-specific performance measures in elite female basketball players. Ten elite female basketball players (age 25.6 ± 4.5 years; height 1.8 ± 0.7 m; and body mass 76.7 ± 8.3 kg) undertook a 90-minute training session involving repeated jumping, sprinting, and game-simulated training. Indirect muscle damage markers (i.e., countermovement jump, delayed onset of muscle soreness [DOMS], and creatine kinase [CK]) and sport-specific performances (i.e., change-of-direction [COD] test and suicide test [ST]) were measured before and 24 hours after training. These measures were also collected 1 week after training to determine the reproducibility of the basketball-specific performance measures. A significant reduction in lower-body power (−3.5 ± 3.6%; p ≤ 0.05), while a significant increase in DOMS (46.7 ± 26.3%; p ≤ 0.05) and CK (57.6 ± 23.1%; p ≤ 0.05) was observed 24 hours after exercise. The ST was also significantly increased (2.1 ± 1.8%; p ≤ 0.05), although no difference was observed for COD (0.1 ± 2.0%; p > 0.05). The intraclass correlation coefficient and coefficient of variation for the COD and ST were 0.81 and 0.90, respectively, and 1.9 and 1.5%, respectively. In conclusion, appropriate recovery should be considered the day after basketball-specific training sessions in elite basketball players. Furthermore, this study showed the usability of performance measures to detect changes during periods of EIMD, with acceptable reproducibility and minimal measurement error.

Introduction

Basketball is a team sport, demanding players to be agile while performing strenuous actions interspersed with active and passive recoveries (^40,41). For example, match intensity can reach up to 95% of maximum heart rate value, with players covering more than 3% of the total running distance above 18 km·h⁻¹ (³⁴). Furthermore, players undergo quick transitions between offensive and defensive plays, with 576 transitions recorded during a full match (⁴). Accordingly, players are expected to train at a level equivalent to, or above, the physiological demands required during gameplay. However, the typical movement patterns seen in gameplay, such as jumping and repeated sprint efforts, are known to cause exercise-induced muscle damage (EIMD) because of a combination of eccentric and concentric muscle actions at a high intensity (¹⁵).

Exercise-induced muscle damage is typically accompanied by marked attenuation in muscular performance, delayed onset of muscle soreness (DOMS), reduced range of motion, and impaired kinesthetic awareness because of the mechanical stress imposed on the muscle fibers and disturbances of calcium homeostasis (^1,16,32,36). Collectively, basketball-specific performances may deteriorate during periods of EIMD, impair training quality, and ultimately compromise chronic training adaptation or increase risk of overtraining (⁸). Indeed, a number of studies have reported symptoms of EIMD through increased indirect muscle damage markers (i.e., vertical jump, DOMS, and creatine kinase [CK]) for up to 48 hours after a basketball match in elite male (^2,39), elite female (²⁶) and collegiate male (¹⁸) basketball players. In addition, Chatzinikolaou et al. (²) reported attenuated sprint, agility, and vertical jump performance for up to 72 hours after basketball match play in elite male basketball players. Conversely, Moreira et al. (²⁶) showed no changes in sprint and agility performance despite the presence of EIMD 24–48 hours after a basketball match in elite female basketball players. These discrepancies may be due to differences in exposure to eccentric loading, given that exercise intensity during a basketball match is distinct between playing level and gender (^27,37). Nonetheless, the physiological stress during a full basketball match seems sufficient to cause EIMD even in highly trained basketball players. Although these findings highlight the need to provide sufficient recovery after a full basketball match, it is uncertain whether a basketball-simulated training session causes EIMD. Kostopoulos et al. (²²) showed that a 10-minute basketball-simulated training session increased CK and impaired leg strength and knee range of motion for up to 96 hours after exercise. However, inferring the implications of these findings specifically to basketball is difficult, given that basketball-specific measures were not included (e.g., sprint and change of direction and vertical jump performance), the training session was substantially shorter than that typically prescribed for elite basketball players (⁵) and the participants were recreational male basketball players. Given that some symptoms of EIMD (such as CK) are distinct between genders (²⁰) and are considerably less in highly trained athletes compared with their lesser-trained counterparts (⁴³), the acute responses of a basketball-specific training session may differ in elite female basketball players.

Another consideration when monitoring the acute effect of a basketball-specific training session is whether the performance indicators are ecologically valid and repeatable. Chatzinikolaou et al. (²) and Moreira et al. (²⁶) examined agility performance during periods of EIMD in elite basketball players using a “T-test,” which while versatile and repeatable (²⁸), is not assigned to a particular area of a basketball court and is limited to forward, lateral, and backward movements. Alternatively, Pyne et al. (³⁵) developed a more basketball-specific agility test, which assesses the body's ability to turn and is conducted in an area underneath the basket (a 5 × 7.6 m area known as the “paint”). This protocol is highly applicable for basketball players, given that the capability to turn the body by pivoting the foot is essential (⁴²) and a large period of the basketball match is spent in the “paint” shooting and contesting the ball (³⁵). Another protocol specific to basketball is the “suicide” (also known as the “line drill”), which has been used to identify physiological attributes of basketball players (⁶). However, no studies have examined the reliability of this protocol nor examined the sensitivity of changes during periods of EIMD.

The aim of this study was 2-fold: first, to determine whether a basketball-specific training session causes EIMD in elite female basketball players on performance tests; second, to examine the reliability of these performance measures (i.e., basketball-specific agility test and “suicide” test) that have been specifically developed for basketball players.

Methods

Experimental Approach to the Problem

This study was conducted during the first 2 weeks of a professional basketball preseason period, with the physiological tests being conducted on 3 separate days. During the first week, the participants undertook their first testing session for baseline measures (T_Base) involving assessments of indirect muscle damage markers, countermovement jump (CMJ), body mass, and basketball-specific performance tests. Immediately after the testing session, a typical basketball-specific training session was conducted. The testing session was repeated 24 hours (T₂₄) after the training session to measure its impact of EIMD on basketball-specific performance measures. One week later, the testing session was repeated (T_7d) to determine the reliability of the basketball-specific performance measures. Indirect muscle damage markers were also collected during this testing session to determine whether the athletes were being tested under the same physiological condition for reliability purposes.

Subjects

Ten elite female basketball players (age 17–32 years; height 1.79 ± 0.7 m; and body mass 76.7 ± 8.3 kg) who competed in the Women's National Basketball League (WNBL) during the 2016–2017 season volunteered for this study. The WNBL is a professional, Australian competition that consists of a 16-week regular season and 3-week postseason. All players had been regularly participating in competitive basketball matches during the offseason. To minimize the impact of biological variations, each testing session was conducted at the same time of day, having participants wear the same shoes for every training and testing session and refraining from the following activities: high-intensity exercise for at least 72 hours before T_Base and T_7d, caffeine and food intake for at least 2 hours before each testing session, taking supplements and medication (e.g., anti-inflammatory aids), and recovery sessions in between the testing sessions. The participants were informed of the risks involved in the study and then provided written informed consent before taking part in the study. This study was approved by the Institutional Review Board at James Cook University and that all participants were informed of the benefits and risks of the investigation before signing an institutionally approved informed consent document to participate in the study. This approval covered elite youth athletes (17-33 years). Their parents and guardians, for those under the age of 18, provided written informed consent. Approval was obtained from James Cook University Institutional Human Research Ethics Committee in accordance with the National Health and Medical Research Council national statement. According to an a priori sample size calculation based on previous studies examining indirect muscle damage markers (^9,10), a sample size of 10 participants was sufficient to detect a significant change in variables (>80% of power at an alpha level of 0.05).

Procedures

Basketball-Specific Training Session

The team head coach designed and conducted a high-intensity training session (85 minutes) typically implemented for elite, female, basketball players. As part of the training session, a progressive warm-up was undertaken for 15 minutes consisting of dynamic stretches (i.e., jogging around the court, leg swings in frontal and sagittal planes, bodyweight walking lunges, high knees, butt kicks, and progressive full-court sprints) followed by shooting from the free throw line and 3 point line (5–10 shots). For the next 30 minutes, participants undertook structured maximal effort sprint-based activities including dribbling, passing, and shooting. For example, participants sprinted full court in pairs while passing the ball to each other and ending in a shot at the other end of the court. After 5 minutes of recovery, the participants then undertook an intense, full-court, scrimmage session replicating match play that consisted of three, 6- to 8-minute periods separated by ∼5 minutes of rest. To determine the physiological stress induced by the basketball-specific training session, blood samples were collected using finger prick before and immediately after the training session for the analysis of blood lactate (Lactate Pro 2; Arkray, Japan, Tokyo).

Indirect Muscle Damage Markers

The countermovement jump was conducted to gain insight of the player's neuromuscular properties during periods of EIMD. Three maximal jump attempts were recorded with 15–30 seconds of rest between each attempt (Yard Stick; Swift Performance, Queensland, Australia), and the greatest jump height subsequently reported. To ensure stability across conditions, the participants were instructed to use their arms to gain momentum, maintain proper posture and body alignment throughout the movement with a self-selected depth, avoid excessive swaying, and ensure that their heels were in contact with the floor during the eccentric movement before takeoff (¹⁹). Based on these jump height measures, lower extremity power was calculated using the following equation (¹⁴):

From the CMJ test, jump height and lower body power output measures were reported. The participant's level of DOMS was determined using a visual analog scale with 1 defined as “no soreness” and 10 as “very, very sore” (¹³). The general delayed onset of muscle soreness (G-DOMS) score was ascertained by asking participants how sore their muscles were overall, whereas DOMS of their lower extremity delayed onset of muscle soreness (L-DOMS) was assessed through questioning after they completed a bodyweight squat until their knees were flexed to approximately 90°. Creatine kinase (CK) levels were measured from a 30-µl fingertip, capillary blood sample using a colorimetric assay procedure (Reflotron; Boehringer Mannheim, Mannheim, Germany). The CK measures were reported from one serum blood sample that was immediately pipetted to a test strip. The previously reported intra-assay coefficient of variation for this assay procedure using the same equipment was 7.2% (¹²).

Basketball-Specific Performance Tests

Performance assessments previously developed for basketball players were examined in this study and included a change-of-direction (COD) test and a line drill or suicide test (ST) (³⁵). For the COD test, the participants ran in a zigzag fashion around the cones within a 5 × 7.6-m area of the basketball court at maximal effort (Figure 1). Timing gates (Swift performance) were positioned at the starting/finishing line to record the test duration. The participants completed the COD test 3 times at a submaximal effort with gradual increases in intensity for each bout for familiarization purposes. After the familiarization bouts, time of test completion was recorded for 3 maximal attempts with 2 minutes of rest between each attempt and the best time reported. The COD test was developed as a basketball-specific test that was performed in the restricted area of the basketball court underneath the basket (³⁵). Basketball players were familiar with this type of movement and location because of the game rules that imposed a timing restriction within this area and the game activities typically undertaken in this area (e.g., receive, shoot, and contest the ball on missed shots). For ST (³⁵), participants sprinted back and forth between the baseline and the closest free-throw line, half court, furthest free-throw line, and full court line, respectively. Similar to the agility test, timing gates were positioned at the start/finish line to record test duration, and the participants performed the test once at submaximal effort for familiarization. As participants were very familiar with this test, because of their previous training experience, participants completed only 1 trial of ST with maximal effort.

Figure 1.: Schematic representation of dimensions for the change-of-direction test.

Statistical Analyses

The measure of central tendency and dispersion was reported as mean ± SD. A 1-way repeated-measures analysis of variance (ANOVA) with Bonferroni's pairwise comparisons was used to identify differences in variables between testing sessions (i.e., T_Base vs. T₂₄; T_Base vs. T_7d). Effect sizes (ESs) (Cohen's d) were calculated to determine the magnitude of differences between measures with their associated 95% confidence intervals (CI). The interpretation of ES was as follows: ≥0.8 as large, 0.79–0.5 as moderate, and <0.5 as small (³). The repeatability and degree of measurement error of the physical performance measures were examined using intraclass correlation coefficients (ICCs; 2-way ANOVA) and intraindividual coefficient of variation (CV) with associated 95% CI, respectively. After confirmation of homoscedasticity, the systematic bias and 95% limits of agreement (LOA) were also calculated to explore the random error of the physical performance measures. The worthwhile differences for the physical performance measures were also computed based on a nomogram using the estimation of the measurement repeatability error in accordance with the CV (²⁹). Worthwhile differences for the current sample size (n = 10) were determined using the linear regression equation: y = 1.5182x + 0.2382 (¹¹). All analyses were conducted using the Statistical Package for Social Sciences (version 24, SPSS, Inc., Chicago, IL, USA).

Results

Training-Induced Stress

The lactate values were significantly increased (t₍₉₎ = −3.903, p = 0.004; ES = 3.24 [2.11–4.36]) from before (1.7 ± 0.7 mmol·L⁻¹) to immediately after (7.2 ± 4.3 mmol·L⁻¹) the training session. Significant differences between testing sessions were identified for CK (F_{(2, 18)} = 17.07, p < 0.01), G-DOMS (F_{(2, 18)} = 12.85, p < 0.01), L-DOMS (F_{(2, 18)} = 14.93, p < 0.01), power output (F_{(2, 18)} = 4.69, p = 0.023), and ST (F_{(2, 18)} = 8.31, p < 0.01). Post hoc analyses showed that power output was significantly lower (p = 0.038), whereas G-DOMS (p < 0.01), L-DOMS (p = 0.011), CK (p < 0.01), and ST performance (p = 0.017) were significantly greater (p ≤ 0.05) at T₂₄ compared with T_Base with all comparisons exhibiting moderate to large ES (Table 1). Jump height was similar across all testing sessions (F_{(2, 18)} = 2.90, p = 0.08), with a moderate ES noted between T₂₄ and T_Base values (Table 1). There was no significant difference (F_{(2, 18)} = 0.067, p = 0.935) in COD performance between T_Base and T₂₄ with a small ES (Table 1).

Table 1.: Measures of jump height, lower-body power (Power), general (G-DOMS) and lower-body (L-DOMS) muscle soreness, creation kinase (CK), change-of-direction (COD) test, and suicide test (ST) before the first (T_Base), second (T₂₄), and third (T_7d) training sessions.*

Reliability

When measures were compared between T_Base and T_7d, no significant differences were found for the physical performance measures (power output [p = 0.264], jump height [p = 0.412], COD [p = 1.000], and ST [p = 0.089]) and indirect muscle damage markers (CK [p = 1.000], G-DOMS [p = 1.000], and L-DOMS [p = 0.159]), with small to moderate ES (Table 2). The repeatability of the physical performance measures based on ICC, mean difference (%), systematic bias, LOA, CV, and worthwhile difference ranged from 0.81 to 0.95, 0.4 to 3.5, 0.03 to 0.6, 0.4 to 3.8, 1.5 to 4.1, and 2.7 to 6.6%, respectively (Table 2). The Bland–Altman plots for jump height, lower body power, COD test, and ST test are shown in Figure 2.

Table 2.: Measures of mean differences (Diff), intraclass correlation coefficient (ICC), average bias (Bias), 95% limits of agreement (LOA), intraindividual coefficient of variation (CV) and worthwhile difference (WD) for countermovement jump (CMJ), lower body power (Power), change-of-direction (COD) test, and suicide test (ST).

Figure 2.: Bland and Altman plots of the differences between baseline and the testing session 1 week later for jump height (JH; A), lower-body power output (Power; B), change-of-direction test (COD; C) test, and suicide test (ST; D).

Discussion

This study examined the impact of EIMD on basketball-specific performance measures and the reliability of these measures. The training session, which consisted of multiple sprints and jumping exercises, caused EIMD 24 hours later with impairment in jumping ability (i.e., power) and repeated-sprint performance (i.e., ST), although COD performance was not affected. When comparing measures between T_Base and T_7d, no differences were found for CMJ, power, COD, and ST with good to excellent reliability.

The acute responses of basketball-specific training showed that CK, G-DOMS, and L-DOMS were significantly increased with a concomitant reduction in jump height and power output at T₂₄, suggesting that muscle fiber damage occurred as a result of the training session. These findings were expected, given that basketball-simulated training involves heavy eccentric loading by deceleration during sprints and jumping actions, which causes EIMD (²²). The magnitude of changes in CK (i.e., ∼2-fold increase) and DOMS (∼3-fold increase) and CMJ (i.e., ∼6% reduction) in this study are in line with previous findings 24 hours after a basketball match in elite female (²⁶) basketball players. Similar findings have also been reported 24 hours after a basketball match in elite male (^2,18,39) basketball players. However, comparisons in these measures should be considered with caution, given that gender differences in CK and muscle function have been shown previously (^20,24). Based on the similarity in training background of participants and the degree of indirect muscle damage markers reported from our findings and that by Moreira et al. (²⁶), it is reasonable to assume that the physiological stress induced by the basketball-specific training session in this study replicated a basketball match.

Interestingly, Kostopoulos et al. (²²) reported a 4-fold greater CK level and DOMS 24 hours after a 10-minute basketball-simulated training session. However, the participants in their study were recreational athletes that were not regularly exposed to basketball-specific activities. This protection against muscle fiber damage after multiple bouts of exercise with eccentric loading is known as the repeated bout effect (³⁰) and highlights the importance of accounting for training background and previous training experience when monitoring athletes after high-intensity training sessions (¹³). It is also important to note that the training intensity and volume were not controlled or documented in this study with the scrimmage during the later half of the training session potentially resulting in interindividual variation in training volume. However, the training session was structured to ensure that all participants undertook the same type and number of exercises during the first 30 minutes before the scrimmage, irrespective of playing position. This approach of incorporating conditioning exercises followed by a scrimmage allows for better monitoring of training volume and is distinct to previous studies that have examined the impact of EIMD after basketball matches only (^2,26).

Although indirect muscle damage markers were significantly altered 24 hours after the basketball-specific training session, no changes were found in COD performance. These results are similar to that reported by Moreira et al. (²⁶), where agility/COD performance was unaltered 24 hours after a basketball match in elite female basketball players despite changes in indirect muscle damage markers (i.e., CK, DOMS, and CMJ). Interestingly, Chatzinikolaou et al. (²) reported attenuation in agility/COD performance with a concomitant increase in indirect muscle damage markers 24 hours after a basketball match. The discrepancies in these findings may be attributed to the differences in the match playing time of each participant. For example, the participants in the study by Moreira et al. (²⁶) were allowed substitutions during the 40-minute basketball match with an average playing time of 18 minutes. Although participants in this study were not given substitution allowance during their scrimmage, the duration and the number of sets played were substantially less compared with a typical game. Conversely, Chatzinikolaou et al. (²) had each participant play through the entire 40-minute basketball match. Accordingly, the greater level of playing time, and therefore eccentric-loading exposure, may have induced agility/COD performance changes among participants in the study by Chatzinikolaou et al. (²).

In contrast to COD performance, this study showed that the ST performance was impaired. Given that this is the first study to report on changes in ST performance in response to EIMD, comparing these findings to previous studies was difficult at present. Chatzinikolaou et al. (²) and Pliauga et al. (³³) reported significant increases in 10-meter sprint times 24 hours after a basketball match in elite male basketball players, suggesting that sprint ability is impaired as a result of EIMD in such athletes, although repeated-sprint ability cannot be inferred from their findings. Other studies have shown impaired repeated-sprint ability in competitive male soccer players (^21,25), although these results are not directly comparable to the current findings because of differences in the repeated-sprint protocol, athlete type, and sex. Nonetheless, the attenuation in ST performance in this study provides insight on the impact that EIMD has on repeated-sprint performance in basketball players. However, given that every effort was made to equate training volume during the first half of the training session, more research is necessary to confirm whether EIMD is caused by exercise intensity, training volume, or by both training variables. In addition, given that performance measures were collected in a highly controlled environment, as opposed to match situations with unpredictable constraints, further research is needed to confirm whether basketball-specific training sessions cause attenuation in performance during gameplay and whether EIMD remains elevated beyond 24 hours after a basketball-specific training session.

The high level of reliability and minimal measurement error for the CMJ and lower body power output measures reported in this study are in line with previous studies among elite basketball players (^7,23). For the COD test, results showed an ICC of 0.81 and a CV of 1.9%, indicating good reliability with minimal measurement error. Furthermore, the systematic bias of the COD test was minor (0.03 second) with the LOA being 0.42 second and 95% of all between-trial differences within 0.21 second of the bias. Recent studies have also shown good reliability measures in COD performance based on ICC calculations in elite senior male (³⁸) and junior male (⁴⁴) basketball players. Given the similar reliability measures in this study and that reported by others (^38,44), it seems that the COD performance of both elite female and male basketball players is highly stable across testing conditions.

For the ST test, no significant differences were observed between T_Base and T_7d. Furthermore, the ICC and CV were 0.90 and 1.5%, respectively, demonstrating excellent reliability. In addition, the systematic bias of this test was minimal (−0.6 second), with the LOA being 1.27 second and 95% of all between-trial differences within 0.6 second of the bias. Studies have previously reported good to excellent reliability using ICC calculations for physical assessments involving multiple repeated sprints in basketball players (^31,44). However, the repeated-sprint protocols have typically consisted of identical sprint distances, passive recoveries in-between each sprint, and sprint durations of only 4–6 second (^31,44). Contrarily, the ST is a continuous protocol for ∼30 second without recovery, and the distance of each sprint increases after each directional change. Subsequently, the ST places more demand on the anaerobic glycolytic system as opposed to the anaerobic system used during the shorter sprint performance protocols (¹⁷). Although short repeated sprints are important performance indicators in basketball (Kostopoulos et al. (²²)), situations of having to repeatedly sprint back and forth across the full length of the court without recovery (i.e., ST performance) is common during a basketball game (Scanlan et al. (³⁷)). Thus, the current findings provide insight on the usability of ST to determine performances within basketball-specific constraints and physiological demands.

Practical Applications

Exercise-induced muscle damage was associated with attenuation in vertical jump ability and repeated sprint performance, although COD performance was unaffected. Accordingly, trainings sessions consisting of basketball-specific conditioning exercises and scrimmage should be considered with caution if incorporated 24 hours before an important basketball match or training session involving repeated high-intensity exercises. For the reliability measures, CMJ, power output, COD test, and ST were repeatable indicating the usability of these protocols for monitoring fatigue and/or improvement as a result of training adaptation in elite female basketball players.