Baixe o app para aproveitar ainda mais
Prévia do material em texto
Introduction A competitive game of professional rugby league is a high-im- pact collision sport played over approximately 90min. Like other football codes, rugby league has been characterized as a high-in- tensity sport that combines intermittent bouts of very intense anaerobic exercise interspersedwith longer lower-intensity peri- ods of aerobic exercise. Due to these activity demands, rugby league players require both a high level of muscular strength and power combined with a well-developed aerobic capacity. Additionally, other physiological factors such as increased speed, speed-endurance, agility and quickness are considered impor- tant for success in rugby league [22]. Abstract The purpose of this study was to examine the influence of over- reaching onmuscle strength, power, endurance and selected bio- chemical responses in rugby league players. Seven semi-profes- sional rugby league players (V˙O2max = 56.1 ± 1.7mL ·kg–1 ·min–1; age = 25.7 ± 2.6 yr; BMI = 27.6 ± 2.0) completed 6 weeks of pro- gressive overload training with limited recovery periods. A short 7-day stepwise reduction taper immediately followed the over- load period. Measures of muscular strength, power and endur- ance and selected biochemical parameters were taken before and after overload training and taper. Multistage fitness test run- ning performance was significantly reduced (12.3%) following the overload period. Althoughmost other performancemeasures tended to decrease following the overload period, only peak hamstring torque at 1.05 rad· s –1 was significantly reduced (p < 0.05). Following the taper, a significant increase in peak hamstring torque and isokinetic work at both slow (1.05 rad· s –1) and fast (5.25 rad· s –1) movement velocities were observed. Min- imum clinically important performance decreases were mea- sured in a multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-upmax following the overload period. Following the taper, minimum clinically important increases in the multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-upmax and 10-m sprint performance were observed. Compared to resting measures, the plasma testoster- one to cortisol ratio, plasma glutamate, plasma glutamine to glu- tamate ratio and plasma creatine kinase activity demonstrated significant changes at the end of the overload training period (p < 0.05). These results suggest that muscular strength, power and endurancewere reduced following the overload training, in- dicating a state of overreaching. The most likely explanation for the decreased performance is increasedmuscle damage via a de- crease in the anabolic-catabolic balance. Key words Athlete monitoring fatigue · recovery · hormones · team sport · overtraining Tra in in g & Te stin g 1 Affiliation 1 School of Leisure, Sport and Tourism, University of Technology, Sydney, Australia 2 School of Health and Human Performance, Central Queensland University, North Rockhampton, Australia 3 School of Medical Sciences, RMIT University, Bundoora, Australia Correspondence Aaron Coutts Ph.D. · School of Leisure, Sport and Tourism · University of Technology · Kuring-gai Campus · P.O. Box 222 · Lindfield, NSW 2070 · Sydney · Australia · Phone: + 61295145188 · Fax: + 61295145195 · E-mail: aaron.coutts@uts.edu.au Accepted after revision:March 27, 2006 Bibliography Int J Sports Med © Georg Thieme Verlag KG · Stuttgart · New York · DOI 10.1055/s-2006-924145 · Published online 2006 · ISSN 0172-4622 A. Coutts1 P. Reaburn2 T. J. Piva3 A. Murphy1 Changes in Selected Biochemical, Muscular Strength, Power, and Endurance Measures during Deliberate Overreaching and Tapering in Rugby League Players The physical conditioning programs prescribed for rugby league players usually consist of a high volume of resistance training that focuses on strength and power development, aerobic fitness training, speed and agility sessions, as well as skill and tactical development sessions. Like most high-level team sport athletes, rugby league players often complete a large volume of high-in- tensity training during the preseason preparation period so that these physical capacities can be optimized prior to the competi- tion season. These high training loads may increase the risk of rugby league players developing overreaching (OR) or over train- ing (OT). High training loads with insufficient periodization of recovery periods has been suggested to cause OR and OT in team sport players, such as soccer [18,25], European handball [8] and bas- ketball [14]. To date, there have only been a few studies that have examined the influence of OR on muscular strength, power and endurance in team sport athletes [8,18]. These studies have shown that when inappropriate physical training is completed with inadequate recovery or regeneration, both reduced strength performance and physiological function ensues. For example, Kraemer et al. [18] demonstrated that soccer players entering a competitionwith symptoms of OR such as low plasma testoster- one concentration and elevated plasma cortisol, experienced performance reductions in 20-yard sprint velocity, vertical jump height and peak torque production during a maximal isokinetic leg extension in the course of an 11-week soccer season. This study highlighted that biochemical measures could be used to identify fatigue in team sport athletes during the season. How- ever, at present, there is still relatively little information about the usefulness of these markers monitoring for fatigue in team sport athletes. Relatively few studies have systematically examined the use of biochemical measures for monitoring fatigue and recovery in team sport athletes [3–5,15,25]. In these studies, various hor- monal [3–5,25], hematological [34], and immunological [5] parameters have been used to identify early signs of OR/OT. However, in accordance with similar studies that have been con- ducted on endurance trained athletes [10], these studies have not been able to provide clear and consistent biochemical markers of impending OR/OT for team sport athletes. The aim of this research was to examine the influence of over- reaching on muscle strength, power and endurance characteris- tics in rugby league players. This is the only investigation, to date, to deliberately induce a state of OR in rugby league players or team sport players in general. Additionally, this study is also the first to examine changes in various performance and bio- chemical markers of OR/OT in a team sport using a prospective overload-training study. In accordance with similar research with endurance athletes [9], it was hypothesized that increased physical training will result in decreased performance and phys- iological function, but will not significantly alter biochemical markers previously used to identify OR/OT. Methods Subjects Seven rugby league players (V˙O2max = 56.1 ± 1.7ml ·kg–1 ·min–1 or 170.4 ± 8.2mL ·kg bm0.75 ·min–1; age = 25.7 ± 2.6 yrs; BMI = 27.6 ± 2.0) from the same club volunteered to participate in the study. The club competed in a state level rugby league competition (Queensland Cup, Australia), which is the highest level of compe- tition in the state for regional teams and players. Prior to partic- ipation in this study, all players received written and verbal ex- planation of the study informing them of all risks and benefits associated with participation. Written informed consent was then obtained. University Human Ethics Review Panel approval was given for all experimental procedures. Physical training All subjects completed six weeks of physical training that in- cluded 5–7 sessions ·week–1 of field-based specific rugby league training, aerobic endurance development, resistance, skill and speed/agility training. The physical training in this study wascompleted during the specific preparation period of the training season and commenced 8 weeks prior to the first official compe- tition match of the season. The physical training program was designed to progressively overload the players during the initial six weeks so that a state of OR was induced. The mean training duration was progressively increased from ∼ 6 to 13 h ·week–1 during the 6-week overload training period, through the addi- tion of both resistance training, match play and rugby league specific training (Table 4). The training load and monotony for each subject was calculated according to the methods of Foster et al. [6]. This method has previously been shown to be useful for measuring a team sport athlete’s perception of physical train- ing loads [17]. Following the 6 weeks of physical training, all subjects com- pleted the same taper. A step-reduction taper consisting of three field sessions and two resistance training sessions was com- pleted over a 7-day period (Fig.1). During the taper, there was a reduction in both training time (55%) and training intensity (17.4%). Resistance training All players completed the same 7-week periodized resistance- training program during the study. Resistance training sessions were completed 2–3 days ·week–1. The resistance training exer- cises prescribed during the overload period and taper are shown in Tables 1 and 2, respectively. The resistance exercises com- pleted on day 1 and 2 in Tables 1 and 2were alternated through- out the training period. The weight on the bar for core exercises was calculated according to the methods suggested by Baker [1]. The players were encouraged to adjust theseweights if they were too heavy or too light. When training loads were altered, players were instructed to inform the chief investigator. A detailed de- scription of the resistance training periodization is shown in Ta- ble 3. All resistance-training sessions were completed with at least 24-h recovery from the previous resistance training session. Testing procedures Various physiological and performance measures were taken in the 24 h prior to commencing the 6-week training protocol, fol- Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 2 lowing the 6-week overload training and at the completion of the 7-day taper. Additionally, to determine the time-course of changes in endurance shuttle running performance, the multi- stage fitness test (MSFT) was conducted 24 h prior to training, following the overload training period, and 5 days of the taper. All measures were taken under standardized conditions and at the same time of day. Performance tests All subjects were tested for various anthropometric, muscular endurance, strength and power measures before and after the training and taper periods. All tests, except the MSFT, were con- ducted following 24 h of rest. TheMSFTwasmeasured during the final day of training during the taper (day 5). Anthropometry measures of the sum of nine skinfolds, body mass, stature and girths were taken by a trained anthropometrist using standard laboratory methods [27]. Multistage fitness test Endurance performance was measured using the MSFT, using previously reportedmethods [28]. For this test, the subjects were required to run back and forth along a 20-m grassed track, keep- ing in time with a series of audio signals from a compact disk (Australian Coaching Council, Canberra, ACT). The running speed was progressively increased until the players reached volitional exhaustion. MSFT performance was taken as final distance trav- elled when the player reached volitional fatigue. The intraclass correlation coefficient (ICC) for test-retest reliability and typical error of measurement (TEM) for the MSFT were 0.93 and 3.5%, respectively. Isoinertial strength testing Muscle strength testing included a standardized warm-up fol- lowed by a 3-RM parallel squat, 3-RM bench press and chin-up maximum (chin-upmax). The 3-RM parallel squat and bench press testing procedures included two to three warm-up sets of five to Table 1 Resistance training exercises completed during the 6-week training overload period Day 1 Day 2 Prone hamstring flicks* internal/external shoulder Box jumps (40 cm)* bench throw* Hang clean* push press* Back squat underhand weighted chin-ups Deadlift DB incline bench press Barbell step-ups (40 cm) front military press Hami-glut-raise abdominal circuit * Power exercises Fig.1 Mean (± SD) daily training load (AU = Arbitrary unit). Table 2 Resistance training exercises completed during the 7-day taper period Day 1 Day 2 Prone hamstring flicks internal/external shoulder Full squat hang clean* Bench throw* power shrug* Clean pull* split jerk* Push press* narrow grip bench press Hami-glut-raise close grip pulldown Abdominal circuit * Power exercises Table 3 Description of prescribed resistance training completed during the 7-week training period Week 1 2 3 4 5 6 Taper Repetitions per set 8 7 6 5 6 5 5 Sets per session 23 24 25 27 27 30 18–21 Goal intensity (%1-RM)* 78.5 81 83.5 86 83.5 86 55 Rest period (min) 2 2 2 2 2 2 2.5 Sessions · week –1 2 2 3 3 3 3 2 *General goal intensities are given only as a guide. Power exercises were com- pleted at lighter %1-RM than strength exercises and the actual weight was individ- ualized by the coach Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 3 eight repetitions with light to moderate resistance. A successful parallel squat required the thigh to descend to a parallel position, where the trochanter head of the femurwas in the same horizon- tal plane as the superior border of the patella. A successful bench press required the bar to be slowly lowered to the chest of the subject and returned to full extension of both elbow joints. The subjects were required to keep their hips and feet on the bench and floor, respectively, at all times during each lift attempt. The reliability of parallel squat (ICC: r = 0.96 and TEM% 2.32) and bench press (ICC: r = 0.98 and TEM% 1.5) measures for this group was high. The chin-upmax test was completed at least 10min after the bench press test. During this test, the subjects were instructed to attempt asmany full, unassisted, chin-ups as possible until vo- litional fatigue. Each chin-up was completed on a horizontal bar raised 2.5m above the floor. A successful chin-up required the subject to start with their chin above the horizontal bar and to lower their body until full extension in both elbows and then lift their body weight until the subjects chin returned to the starting position. If assistance was offered by a spotter during any lifting attempt, then the subject was instructed to stop. Subjects were allowed three chin-upmax trials with the highest number of repe- titions being recorded. The reliability of the chin-upmax test (ICC: r = 0.99 and TEM% 2.6) for this group was high. Speed Running speed was assessed by 10-m and 40-m sprint times us- ing electronic timing gates (Swift, Lismore, Australia) with the photo-electric cells set at approximately chest height. Timing gates were positioned in a straight direction at 10m and 40m from a marked starting point. On an audible command, the play- ers sprinted as quickly as possible along the 40-m course. Timing commenced when the photoelectric cells positioned at the start were initiated. Time to cover the 10-m and 40-m distance was measured to the nearest 0.01 s, with the faster of two trials being recorded. The reliability of 10-m (ICC: r = 0.91 and TEM% 2.0) and 40-m (ICC: r = 0.91 and TEM% 1.9) sprint tests was high. Isokinetic strength Isokinetic strength of the knee extensors and knee flexors (dom- inant leg) was measured using an isokineticdynamometer (Bio- dex 3.0, Biodex Corporation, Shirley, NY, USA), which recorded instantaneous muscular torques at preset constant angular ve- locities of 1.05 rad· s–1 and 5.25 rad · s–1. Prior to beginning the isokinetic strength assessment, subjects completed a standard- ized 5-min warm-up of cycling on a cycle ergometer (Monark 818E, Monark, Stockholm, Sweden) at a cadence of 50 rpm with a load of 0.5 kp. The subject was then seated on the dynamome- ter in an adjustable chair, and stabilized by straps so that the axis of rotation of the knee joint was aligned with the axis of rotation of the dynamometer shaft. A resistance pad was positioned on the thigh proximal to the knee joint so that the knee extensors and flexors could be isolated. Straps were used to stabilize the upper body, hips and nondominant leg. The cuff of the dyna- mometers’ lever arm was attached proximal to the medial mal- leoli. All positions were recorded and standardized to assure reli- ability of testing conditions. Prior to each test set, a series of submaximal trials at each testing velocity were conducted to prepare them for each test. Concen- tric strength of the knee extensors and flexors was determined during one set of three maximal concentric contractions of the quadriceps and hamstring muscles through a 90� range of mo- tion at 1.05 rad · s–1 and 5.25 rad· s–1. The highest gravity-cor- rected torque produced (Nm) during each set was taken as the maximal isokinetic strength for that velocity. Total work (J) com- pleted for each set at both lifting velocities was also calculated during each testing session. Vertical jump Vertical jump (VJ) height was assessed using a Vertec® jumping device consisting of a series of moveable marker vanes spaced at 1-cm intervals (Sports Imports, Columbus, OH, USA). Each subject stood side-on to the Vertec® with their heels placed on the ground. Prior to each test jump, the subjects were asked to reach upward as high as possible fully elevating the shoulder to displace the zero reference vane. The take-off was from two feet with no preliminary steps or shuffling. An arm swing and coun- ter movement was used with the subject jumping as high as pos- sible to displace the vane. The height of the jump (cm)was calcu- lated as the difference between the highest vane reached and the zero reference vanes. Each subject performed three trials, with the best of these trials being recorded. The reliability of VJ mea- sures for this test was high (ICC: r = 0.97 and TEM% 2.1). Biochemistry Testosterone, cortisol, adrenocorticotrophic hormone (ACTH), creatine kinase (CK), erythrocytes, hemoglobin, hematocrit, plas- ma glutamine and glutamate measures were taken prior to, and following the 6-week overload period and also following the 7- day taper. All hematological measures were taken in a fasted state between 5:30 and 7:30 a.m. in the mornings of testing to avoid circadian variations. Table 4 Mean training load, monotony and frequency measured during the study period (mean ± SD) Measure Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Taper 6-week train- ing period Training load (AU) 1387 ± 105 1811 ± 159# 2285 ± 121# 2403 ± 167# 2712 ± 219# 3296 ± 298# 1420 ± 25# 2316± 86 Monotony 1.35 ± 0.07 1.17 ± 0.10# 1.85 ± 0.13# 1.51 ± 0.23# 2.00 ± 0.16# 1.84 ± 0.10 1.29 ± 0.01# 1.57 ± 0.32 Sessions completed 5 5 6 6 6 7 5 35 # Significantly different to previous measure (p < 0.05); AU = arbitrary unit Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 4 Blood samples were taken by a trained phlebotomist in a quiet laboratory room maintained at constant temperature (20– 23 �C). All subjects were asked to refrain from drinking coffee, tea, chocolate or cola drinks that morning or the previous even- ing, as well as avoiding alcohol during the previous 24-h period. All blood samples were takenwith the subject in a resting, seated position, following 20min of seated rest. Three 10-mL samples (1 × lithium heparin tubes [10mL]; 1 × pre-chilled ethylenedia- minetera-acteic acid (EDTA) [10mL]; 1 × serum separator tube (SST) tube [10mL]) of blood were collected from the antecubital vein on each occasion, using a winged cannula attached to a va- cutainer (Becton Dickinson, Rutherford, NJ, USA) bleeding sys- tem. All samples were then stored within an ice-bath immedi- ately following collection. The lithium heparin tubes were cen- trifuged for 5min at 4000 g. The samples were then transported in a refrigerated transport pack for immediate analysis. Once the samples arrived at the diagnostic laboratory (approximately 10min), they were prepared for analysis. Plasma total testosterone was determined via a solid-phase 125I radioimmunoassay using a gamma radiation counter (LKB Wal- lac, St Albans, UK). Plasma cortisol was determined via immuno- assay, through a fluorescence polarization immunoassay (FPIA) using a TDx/TDxFLx analyser (Axysm, Abbott, Irving, TX, USA). Hematocrit, hemoglobin and erythrocyte number were deter- mined with a Coulter® MaxM A/L Flow Cytometer (Coulter Elec- tronics Limited, Luton, UK). Plasma glutamine and glutamate were also determined enzymatically using the method of Lund [21]. All blood analyses, except for ACTH, were conducted at Dr. T.B. Lynch Research and Diagnostic Laboratories, Rockhampton, Australia. All diagnostic laboratories used in this study held cur- rent quality assurance certification (ISO 9001). Statistical analyses Themeans and standard deviations (SD)were calculated for each dependent variable. The data were analyzed using an analysis of variance (ANOVA) for repeated measures to determine if there were differences between each testing occasion. When a signifi- cant F-value was achieved, Scheffé post hoc test procedures were used to locate the difference between the means. The minimum clinically important difference (MCID), or smallest worthwhile change perceived to be practically significant for the average ath- lete, was calculated for most performance variables. MCID was determined to be greater than the typical error of measurement in the performance tests [16]. The MCID for MSFT, vertical jump, 3-RM bench press, 3-RM squat, chin-upmax, 10-m sprint and 40- m sprint were 1.4mL ·kg–1 ·min–1, 1.3 cm, 1.7 kg, 3.3 kg, 0.4 reps, 0.04 s and 0.10 s, respectively. Pearson correlation coefficients were calculated to determine relationships between selected variables. The SPSS statistical software package, version 11.5 (SPSS Inc., Chicago, IL, USA), was used for statistical calculations. The level of significance was set at p ≤ 0.05. Results Physical training In the present study, all subjects completed 6 weeks of progres- sive overload training (Table 4). Training duration was progres- sively increased for each week followed by a significant reduc- tion in training load during the 7-day taper (p < 0.001) (Table 5). The training time during the taper periodwas ∼ 55% less than the previous training week. The training intensity was significantly lower in the taper than the final week of the overload period (RPE: 4.6 ± 0.2 vs. 3.8 ± 0.1; p < 0.01). The time spent during both field and resistance training during the week prior to the taper and during the 7-day taper can be seen in Table 5. During the 6- week overload period, significantly more time (90%, p < 0.001) was spent in field training compared to resistance training. Physiology and performance Table 6 shows the physiological variables that changed signifi- cantly during the 6-week overload training period. There were significant main effects observed inMSFT performance over time (p < 0.01) during the 6-week training period and five-day taper. A significant correlation was observed between the change in MSFT performance and the change in training load (r = – 0.84; p < 0.001). Peak torque developed by both theknee extensors and flexors and the total amount of work completed at a movement velocity of 1.05 rad · s–1 was significantly decreased following the over- load period (p < 0.05) and significantly increased following the taper (p < 0.05). MCID (reductions) were observed for MSFT, VJ, 3-RM bench press, 3-RM squat and chin-upmax performance following the overload training period. In contrast, MCID (in- creases) were observed in MSFT, VJ, 10-m sprint, isoinertial 3- RM bench press, isoinertial 3-RM squat and chin-upmax perform- ance following the taper period. The only MCID for improve- ments in performance from before training to following taper was in chin-upmax. Biochemistry Table 7 shows hormonal changes during the 6-week overload training period. The testosterone to cortisol (T/C) ratio was sig- nificantly decreased with overload training (p < 0.05). No signifi- cant changes were observed in plasma cortisol measures. Addi- Table 5 Training time (min) for the field and resistance training during the study period (mean ± SD) Training Mode Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Taper 6-week training period Field training (min) 239 ± 5 267 ± 6# 326 ± 7# 339 ± 27 350 ± 6 562 ± 16# 185 ± 3# 332 ± 78 Resistance training (min) 104± 3 135 ± 24# 205 ± 14 221 ± 25 262 ± 15 170 ± 24 147 ± 8# 197 ± 63 Combined training (min) 343 ± 5 402 ± 23# 531 ± 12# 560 ± 27# 612 ± 18# 732 ± 38# 332 ± 9# 531 ± 134 # Significantly different to previous measure (p < 0.05) Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 5 tionally, there were no significant changes in any hormonal val- ues during the taper (p > 0.05). Table 8 shows the changes in the hematological variables during the course of the training and taper periods. CK activity signifi- cantly increased during the 6-week training period. No signifi- cant changes were observed over time in erythrocyte number, hematocrit or hemoglobin. Significant changes in CK activity (p < 0.01) were measured during the taper. There were no significant changes in plasma glutamine concen- tration over the 6-week overload training period. However, plas- ma glutamate was significantly elevated at the end of the train- ing period (p < 0.05). Accordingly, the glutamine to glutamate ra- tio (Gln/Glu) was also significantly lower at the end of the train- ing period (p < 0.05) (Table 8). During the taper, plasma gluta- mate (p < 0.05) and Gln/Glu (p < 0.05) were significantly de- creased. Discussion The purpose of this research was to examine the influence of OR on muscle strength, power and endurance characteristics in rug- by league players. The present findings show that with deliberate OR, semi-professional rugby league players have a decreased ca- pacity to produce force at slowermovement velocities. Addition- ally, the present results also demonstrate that inappropriate high-intensity training for rugby league may also cause a tempo- rary reduction inMSFTand thus aerobic endurance performance. In this study, 7 semi-professional rugby league players were de- liberately overreached by increasing resistance training, endur- ance and rugby league specific skill training workloads over a 6- week period. Training load was progressively increased during the 6-week overload period by increasing training frequency and duration, which lead to a reduction in MSFT performance. The 12.3% reduction in MSFT performance during the overload period is well above the typical error of measurement for this test (3.5%) showing that there was both a practically [16] and statistically significant reduction in maximal aerobic running performance. Previous research has shown V˙O2max to decrease following increased training loads in endurance-trained athletes [9,20,33], but not in team sport players [4,35]. The decreased MSFT performance following the 6-week overload training in the present study may be due to a number of physiological and biochemical factors such as reduced muscle glycogen levels, in- creasedmuscle damage, or simply due to acute fatigue diminish- ing maximal effort. The significant reduction in the T/C ratio and elevated CK activity following the 6-week overload training peri- Table 7 Hormonal variables of OR rugby league players during 6 weeks of overload training and 7-day taper (mean ± SD) Measure Pre- training Post- training Taper Testosterone (ng ·dL–1) 573 ± 114 471 ± 129 545 ± 111 Cortisol (μg ·dL–1) 21.2 ± 6.6 22.8 ± 4.7 21.7 ± 4.0 T/C ratio 31.4 ± 6.6 22.11 ± 5.4* 23.9 ± 3.1* Values are means ± SD; T/C = testosterone to cortisol ratio; * significantly different to pretraining (p < 0.05) Table 8 Mean (± SD) hematological measures during a 6-week over- load training and 7-day taper period Measure Pre- training Post- training Taper Creatine kinase (U ·L–1) 414 ± 171 1329 ± 1003* 498 ± 402* Erythrocytes (·106 ·mm–3) 5.07 ± 0.32 4.98 ± 0.34 5.01 ± 0.10 Hemoglobin (g ·dL–1) 155.6 ± 6.5 152.3 ± 4.4 153.6 ± 6.0 Hematocrit (%) 46.1 ± 2.1 45.1 ± 1.7 45.6 ± 2.2 Glutamine (μmol · L–1) 0.542 ± 0.067 0.491± 0.060 0.525 ± 0.036 Glutamate (μmol · L–1) 0.117 ± 0.014 0.143 ± 0.029* 0.120 ± 0.015 Gln/Glu ratio 4.70 ± 0.78 3.54 ± 0.81* 4.41 ± 0.50 * Significantly different to pretraining (p < 0.05) Table 6 Performance and physiological variables during 6 weeks of overload training and 7-day taper (mean ± SD) Measure Pretraining Post-training Taper Body mass (kg) 86.1 ± 10.0 85.3 ± 9.4 85.3 ± 9.6 MSFT (m) 2291± 127 2054 ± 199*M 2437± 67#M Vertical jump (cm) 61.7 ± 10.6 59.4 ± 9.6M 62.4 ± 9.9 M Running speed 10m (s) 1.89 ± 0.09 1.92 ± 0.11 1.88 ± 0.10M 40m (s) 5.42 ± 0.18 5.46 ± 0.20 5.44 ± 0.19 Isoinertial strength 3-RM squat (kg) 141.2 ± 21.8 133.9 ± 18.2M 143.6 ± 24.8M 3-RM bench press (kg) 115.0 ± 18.7 109.3 ± 17.9M 115 ± 17.3M Chin-upmax (reps) 15.6 ± 1.9 13.4 ± 2.1M 16.0 ± 1.7M Isokinetic strength and power 1.05 rad · s –1 Peak quadriceps torque (Nm) 222.4 ± 50.6 164.5 ± 19.5* 239.5 ± 38.2# Peak hamstrings torque (Nm) 151.8 ± 44.9 117.3 ± 20.4* 135.6 ± 16.2# Set work (J) 967 ± 244 724 ± 116* 1074 ± 152#* 5.25 rad · s –1 Peak quadriceps torque (Nm) 149.1 ± 20.9 162.8 ± 15.0 176.2 ± 28.7 Peak hamstrings torque (Nm) 96.5 ± 11.8 108.4 ± 13.6 128.1 ± 22.3* Set work (J) 603 ± 83 705 ± 91 770 ± 103* # Significantly different to previous measure (p < 0.05); * significantly different to pretraining (p < 0.05); Mminimally clinically important difference compared to pre- vious measure Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 6 od suggests that the players were in a catabolic statewith elevat- ed levels of muscle damagewhen the MSFT performance was re- duced. Although there were not significant correlations between the changes in physiological measures and performance, it is likely that these factors did contribute to the reduction in aerobic performance. There were no statistically significant changes in VJ or isoinertial strength tests in the present study. Nonetheless, MCID changes were identified for these test measures. For example, the reduc- tion in VJ, isoinertial 3-RM bench press, isoinertial 3-RM squat and chin-upmax tests during the overload training period were - 3.7%, – 5.0%, – 5.3% and – 13.8%, respectively. Since the reduc- tion in each test score was greater than the respective typical error of measurement, it is suggested that the changes in each of these tests are of practical importance. Significant reductions in peak torque developed by the knee flex- ors at 1.05 rad· s–1 were observed following the overload training period. In contrast to our initial hypothesis, we found that knee flexor and extensor strength measured at slower speeds (1.05 rad · s–1) was significantlyreduced during OR. However, there was a nonsignificant increase in isokinetic knee extensor and flexor strength at faster movement velocities (5.25 rad · s–1). The results suggest that the training undertaken during the 6- week overload period in this study, which consisted of a 68% greater time spent in field training than resistance training, had a greater negative influence on the type I motor units than the type II motor units. This phenomenon was also previously ob- served in 11 elite college level starting soccer players whose peak isokinetic knee extensor strength was reduced at 1.05 rad· s–1, but not 5.25 rad · s–1 during an 11-week soccer season [18]. These previous investigators suggested that the majority of training for soccer players mainly involved type I motor units and, therefore, they were the most effected by the insufficient recovery period. Furthermore, other studies have suggested that the type I myosin heavy chains (MHC) are more affected by run training than re- sistance training [12]. Accordingly, the greater volume of lower intensity “on legs” exercise (e.g., running and skill training; see Table 5) in this study may explain why the isokinetic strength at the lower speeds weremore affected than the higher speeds dur- ing the overload training period. In the present study, hormone and other blood measures were assessed in order to elucidate the mechanisms underlying the changes in muscular strength and power with fatigue and recov- ery. The hormone results show a nonsignificant tendency for a reduction in testosterone concentration and an increase in corti- sol concentration following the overload training period (Table 7). There was also a significant reduction in the T/C ratio follow- ing the overload period. These results agree with other similar research that show that monitoring T/C ratio measures maybe useful for monitoring adaptation and recovery to training and match play stress in team sport athletes [3]. A limitation in the practical application of the results of this study to field is that venipuncture is required which can be intimidating for some players. To overcome this limitation, coaches and scientists may like to consider measuring T/C ratio using noninvasive salivary samples [3]. A reduction in the T/C ratio is generally considered as an indica- tor of the bodies “anabolic-catabolic balance” and has previously been considered a useful tool for diagnosing OR/OT. It is possible that the change in T/C ratio was due to inadequate recovery be- tween exercise sessions at the end of the overload period, which also reduced the rate of muscle protein and glycogen resynthesis, increased muscle damage and increased inflammation, which ultimately lead to reduced ability to generate force. The reduced ability to generate muscular force may also be related to muscu- lar performance measures such as speed, VJ and isoinertial strength. It is also likely that short-term peripheral fatigue may partially explain the diminishedmuscular strength, power and endurance performance following the overload training period. A recent re- view clearly demonstrated that muscle damage can result in im- mediate and prolonged reduction in muscle force generating ca- pacity in both isotonic and isokinetic tests [2]. The measures of muscle damage in the present study, CK activity and plasma glu- tamate, were both significantly elevated at the end of the over- load period, which coincided with significant changes in isoki- netic force at slow velocity and practical reductions in isoinertial strength measures. These results are in agreement with many previous studies showing that overreached athletes usually suf- fer considerable levels of muscle trauma [7,19,31]. Recent investigators have suggested that elevated plasma gluta- mate levels can be used to identify impaired recovery from high- intensity training or an inadequate recovery period [30]. The present results are in agreement with previous studies that have shown increased plasma glutamate and reduced exercise per- formance following intensified training periods [11,30]. Gluta- mate along with glutamine has a role in acid-base balance and de novo synthesis of nucleotides, and is also an important regu- lator of protein synthesis and degradation [29]. Due to these properties, it is most likely that glutamate plays an important role in the repair/regenerative responses to daily muscle loading. Accordingly, we hypothesize that the decreased muscle gluta- mate observed in the present study may also be associated with reduced strength performance following the overload training period. Further research needs to be completed to determine the role that glutamate plays in these processes. Recent studies have also shown the Gln/Glu ratio to decrease fol- lowing intensified training with levels lower than 3.58 suggest- ed, indicating a state of OR [11,30]. In agreement with these pre- vious studies, the significant change in the Gln/Glu ratio ob- served in the current study appeared to be due to increased plas- ma glutamate levels rather than a reduction in glutamine con- centration alone. Furthermore, we also measured a rebound ef- fect following the taper where plasma glutamate decreased and glutamine levels increased so that the Gln/Glu ratio returned to levels previously suggested to represent that athletes were toler- ating training [30]. The failure of the Gln/Glu ratio to return to pretraining levels, in the present study, may suggest a longer taper period may have been warranted. This is supported by re- cent research that has suggested that tapers up to 28 days can show improvements adaptations in physiology and performance [23,24]. Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 7 This study, to our knowledge, is the first to report on endurance, strength, power and biochemical changes during a preseason taper in team sport athletes. Most performance tests tended to improve following the seven-day taper, suggesting some adapta- tion had taken place. Following the taper, only isokinetic mea- sures of set work at 1.05 and 5.25 rad· s–1 and peak hamstring torque at 5.25 rad· s–1 were significantly improved from baseline measures following the 7-day taper. Notably, however, most oth- er performance variables (MSFT, VJ, 3-RM squat, 3-RM bench press, chin-upmax and 10-m sprint) demonstrated MCID changes with tapering. Combined, these results show that a short, step- wise taper can concurrently improve endurance, strength and power measures in team sport athletes. The MCID increases in MSFT, VJ and 10-m sprint performance, combined with the significant increases in isokinetic strength, show that muscular strength, power and endurance were im- proved with the short taper. It is most likely that the improve- ments in performance are related to changes in muscle fiber properties. Previous studies have shown activity specific changes in myocellular size, power and contractility are dependent upon the type of training completed during the taper [12,26,32]. Despite all biochemical variables reported in this study tending to return to baseline values, only CK activity was significantly changed during the taper, suggesting that training intensity was reduced or an increased tolerance to training loads occurred. These findings agree with the majority, but not all previous re- search employed tapers of between 6–28 days in duration with endurance athletes [24]. To our knowledge, no studies have ex- amined CK activity in response to tapering in team sport ath- letes. However, previous investigators suggested that CK activity has extremely high variability amongst individual athletes and that significant reductions in CK activity are observable during a reduction in training loads following days of intensive, prolonged exercise [13]. The most likelycause for the reduction in CK activ- ity during the taper in the present study is a reduction in the damage to tissue cell membrane from both the repeated strenu- ous exercise and direct muscle trauma. On this basis, we suggest that CK can be used to monitor for acute recovery from heavy training loads in team sport athletes. In conclusion, this study showed that when relatively large loads of aerobic endurance, resistance, speed and skill trainingwith in- adequate periods for recovery are completed, reductions in phys- ical performance could occur. This type of inappropriate training can cause a reduction in the T/C ratio, increased CK activity, in- creased plasma glutamate concentrations and decreased Gln/ Glu ratio. The reduction in performance with OR appears to be related to the type of training completed. For example, in this study, a large volume of training that recruited mostly slower motor units was completed (i.e., field vs. resistance training) and consequently, performance at slower lifting speeds (which recruit these slower motor units) were most negatively affected. The present results also demonstrated that if a stepwise reduc- tion taper is completed following a period of OR, super compen- sation in muscular strength, power and endurance may occur. This super compensation appears to be related to increased anabolism and a decrease in muscle damage. Acknowledgements This research was kindly supported by Dr. T. B. Lynch Pathology Research Laboratories, Rockhampton, Australia. References 1 Baker D. Designing, implementing, and coaching strength training programs for beginner and intermediate level athletes – part 2: Im- plementing the program. Strength Cond Coach 1997; 5: 2–8 2 Byrne C, Twist C, Eston R. Neuromuscular function after exercise-in- duced muscle damage: theoretical and applied implications. Sports Med 2004; 34: 49–69 3 Elloumi M, Maso F, Michaux O, Robert A, Lac G. Behaviour of saliva cortisol (C), testosterone (T) and the T/C ratio during a rugby match and during the post-competition recovery days. Eur J Appl Physiol 2003; 90: 23–28 4 Filaire E, Bernain X, Sagnol M, Lac G. Preliminary results on mood state, salivary testosterone:cortisol ratio and team performance in a professional soccer team. Eur J Appl Physiol 2001; 86: 179–184 5 Filaire E, Lac G, Pequignot JM. Biological, hormonal, and psychological parameters in professional soccer players throughout a competitive season. Percept Mot Skills 2003; 97: 1061–1072 6 Foster C, Florhaug JA, Franklin J, Gottschall L, Hrovatin LA, Parker S, Doleshal P, Dodge C. A new approach to monitoring exercise training. J Strength Cond Res 2001; 15: 109–115 7 Fry AC, Webber JM, Weiss LW, Fry MD, Li Y. Impaired performances with excessive high-intensity free-weight training. J Strength Cond Res 2000; 14: 54–61 8 Gorostiaga EM, Izquierdo M, Iturralde P, Ruesta M, Ibáñez J. Effects of heavy resistance training onmaximal and explosive force production, endurance and serum hormones in adolescent handball players. Eur J Appl Physiol 1999; 80: 485–493 9 Halson SL, BridgeMW,Meeusen R, Busschaert B, GleesonM, Jones DA, Jeukendrup AE. Time course of performance changes and fatigue markers during intensified training in cyclists. J Appl Physiol 2002; 93: 947–956 10 Halson SL, Jeukendrup AE. Does overtraining exist? An analysis of overreaching and overtraining research. Sports Med 2004; 34: 967– 981 11 Halson SL, Lancaster G, Jeukendrup AE, GleesonM. Immunological re- sponses to overreaching in cyclists. Med Sci Sports Exerc 2003; 35: 854–861 12 Harber MP, Gallagher PM, Creer AR, Minchev KM, Trappe SW. Single muscle fiber contractile properties during a competitive season in male runners. Am J Physiol Integr Comp Physiol 2004; 287: R1124– R1131 13 Hartmann U, Mester J. Training and overtraining markers in selected sport events. Med Sci Sports Exerc 2000; 32: 209–215 14 Hoffman JR, Kaminsky M. Use of performance testing for monitoring overtraining in elite youth basketball players. Strength Cond J 2000; 22: 54–62 15 Hoffman JR, Kang J, Ratamess NA, Faigenbaum AD. Biochemical and hormonal responses during an intercollegiate football season. Med Sci Sports Exerc 2005; 37: 1237–1241 16 Hopkins WG. How to interpret changes in an athletic performance test. Sportsci 2004; 8: 1–7 17 Impellizzeri FM, Rampinini E, Coutts AJ, Sassi A, Marcora SM. The use of RPE-based training load in soccer. Med Sci Sports Exerc 2004; 36: 1042–1047 18 KraemerWJ, French DN, Paxton NJ, Häkkinen K, Volek JS, Sebastianelli WJ, Putukian M, Newton RU, Rubin MR, Gómez AL, Vescovi JD, Ratam- ess NA, Fleck SJ, Lynch JM, Knuttgen HG. Changes in exercise perfor- mance and hormonal concentrations over a big ten-soccer season in starters and nonstarters. J Strength Cond Res 2004; 18: 121–128 19 Lakier Smith L. Cytokine hypothesis of overtraining: a physiological adaption to excessive stress. Med Sci Sports Exerc 2000; 32: 317–331 20 Lehmann M, Baumgartl P, Wiesenack C, Seidel A, Baumann H, Fischer S, Spoeri U, Gendrisch G, Kaminski R, Keul J. Training-overtraining: in- fluence of a defined increase in training volume vs. training intensity on performance, catecholamines and some metabolic parameters in Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 8 experienced middle- and long-distance runners. Eur J Appl Physiol 1992; 64: 169–177 21 Lund P. Glutamine. UV method with glutaminase and glutamate de- hydrogenase. In: Bergmeyer HU (ed). Methods of Enzymatic Analysis Metabolites 3: Lipids, Amino Acids and Related Compounds. Wein- heim: VCF, 1985: 357–363 22 Meir R, Newton RU, Curtis E, Fardell M, Butler B. Physical fitness qual- ities of professional rugby league football players: determination of positional differences. J Strength Cond Res 2001; 15: 450–458 23 Mujika I, Padilla S. Scientific bases for precompetition tapering strat- egies. Med Sci Sports Exerc 2003; 35: 1182–1187 24 Mujika I, Padilla S, Pyne D, Busso T. Physiological changes associated with the pre-event taper in athletes. Sports Med 2004; 34: 891–927 25 Naessens G, Chandler TJ, Kibler WB, Driessens M. Clinical useful of nocturnal urinary noradrenaline excretion patterns in the follow-up of training processes in high-level soccer players. J Strength Cond Res 2000; 14: 125–131 26 Neary JP, Martin TP, Quinney HA. Effects of taper on endurance cycling capacity and single muscle fiber properties. Med Sci Sports Exerc 2003; 35: 1875–1881 27 Norton K, Marfell-Jones M, Whittingham N, Kerr D, Carter L, Sadding- ton K, Gore C. Anthropometric assessment protocols. In: Gore CJ (ed). Physiological Testing for Elite Athletes. Champaign, IL: Human Ki- netics, 2000: 66–85 28 Ramsbottom R, Brewer J, Williams C. A progressive shuttle run test to estimate maximal oxygen uptake. Br J Sports Med 1988; 22: 141–144 29 Rowbottom DG, Keast D, Morton AR. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Med 1996; 21: 80–97 30 Smith DJ, Norris SR. Changes in glutamine and glutamate concentra- tions for tracking training tolerance. Med Sci Sports Exerc 2000; 32: 684–689 31 St Clair Gibson A, Lambert MI, Collins M, Grobler L, SharwoodKA, Der- man EW, Noakes TD. Chronic exercise activity and the Fatigued Ath- lete Myopathic Syndrome (FAMS). Internat Sports Med J [online] 2000; 1 32 Trappe SW, Costill DL, Thomas R. Effect of swim taper on whole muscle and single fiber contractile properties. Med Sci Sports Exerc 2000; 32: 48–56 33 Uusitalo AL, Uusitalo AJ, Rusko HK. Exhaustive endurance training for 6–9 weeks did not induce changes in intrinsic heart rate and cardiac autonomic modulation in female athletes. Int J Sports Med 1998; 19: 532–540 34 Varlet-Marie E, Maso F, Lac G, Brun JF. Hemorheological disturbances in the overtraining syndrome.Clin Hemorheol Microcirc 2004; 30: 211–218 35 Verma SK, Mahindroo SR, Kansal DK. Effect of four weeks of hard physical training on certain physiological and morphological param- eters of basketball players. J Sports Med Phys Fit 1978; 18: 379–384 Coutts A et al. Overreaching in Team Sports … Int J Sports Med Tra in in g & Te stin g 9
Compartilhar