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Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts a

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Peter Jensen , Suzanne Scott , Peter Krustrup & Magni Mohr

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Department of Nutrition, Exercise and Sports (NEXS) , University of Copenhagen , Copenhagen , Denmark b

Sport and Health Sciences, College of Life and Environmental Sciences , University of Exeter , Exeter , UK Published online: 23 Jul 2013.

To cite this article: Peter Jensen , Suzanne Scott , Peter Krustrup & Magni Mohr , Journal of Sports Sciences (2013): Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts, Journal of Sports Sciences, DOI: 10.1080/02640414.2013.803591 To link to this article: http://dx.doi.org/10.1080/02640414.2013.803591

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Journal of Sports Sciences, 2013 http://dx.doi.org/10.1080/02640414.2013.803591

Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts

PETER JENSEN1, SUZANNE SCOTT2, PETER KRUSTRUP2, & MAGNI MOHR2 1

Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark, and 2Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK

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(Accepted 26 April 2013)

Abstract Physiological responses and performance were examined during and after a simulated trampoline competition (STC). Fifteen elite trampoline gymnasts participated, of which eight completed two routines (EX1 and EX2) and a competition final (EX3). Trampoline-specific activities were quantified by video-analysis. Countermovement jump (CMJ) and 20 maximal trampoline jump (20-MTJ) performances were assessed. Heart rate (HR) and quadriceps muscle temperature (Tm) were recorded and venous blood was drawn. A total of 252 ± 16 jumps were performed during the STC. CMJ performance declined (P < 0.05) by 3.8, 5.2 and 4.2% after EX1, EX2 and EX3, respectively, and was 4.8% lower (P < 0.05) than baseline 24 h post-competition. 20-MTJ flight time was ~1% shorter (P < 0.05) for jump 1–10 after EX2 and 24 h post STC. Tm increased (P < 0.05) to ~39°C after the warm-up, but declined (P < 0.05) 1.0 and 0.6ºC before EX2 and EX3, respectively. Peak HR was 95–97% HRmax during EX1-3. Peak blood lactate, plasma K+ and NH3 were 6.5 ± 0.5, 6.0 ± 0.2 mmol · l−1 and 92 ± 10 µmol · l−1, respectively. Plasma CK increased (P < 0.05) by ~50 and 65% 0 and 24 h after STC. In conclusion, a trampoline gymnastic competition includes a high number of repeated explosive and energy demanding jumps, which impairs jump performance during and 24 h post-competition. Keywords: jump performance, fatigue, muscle temperature, muscle damage, recovery

Introduction Trampoline gymnastics is a competitive sport with more than one million officially active athletes worldwide and has been an Olympic discipline since 2000. It is also a popular leisure activity and is being employed as a training method in various other sports (Kidgell, Horvath, Jackson, & Seymour, 2007). To date, research on competitive trampoline gymnastics is sparse and consists mainly of studies on injuries associated with trampoline jumping (Sukeik & Haddad, 2011) or the application of trampoline training as part of a rehabilitation strategy (Aragao, Karamanidis, Vaz, & Arampatzis, 2011). No previous studies have examined either trampoline-specific activities performed during competition or the physiological responses and fatigue patterns in elite trampoline gymnasts. Official trampoline competitions consist of a preliminary round of two, approximately 40 s long, routines preceding a final routine. The routines are initiated by explosive start-jumps in order to achieve an optimal height, followed by the functional part

mainly encompassing a series of forwards and backwards somersaults and twists. These types of sportspecific discrete skills have been quantified and described by video analysis in similar physical activities, such as ballet (Twitchett, Angioi, Koutedakis, & Wyon, 2009), contemporary dance (Wyon et al., 2011) and artistic gymnastics (Burt, Naughton, Higham, & Landeo, 2010; Manning, Irwin, Gittoes, & Kerwin, 2011), as well as in high level team sports (Povoas et al., 2012). In addition, jump height appears to be important for trampoline performance, since it gives the gymnast more aerial time for the functional skills. However, changes in jump performance during a trampoline competition have not been determined. Prior to the first routine and the final, trampoline gymnasts normally warm-up thoroughly, but it may be difficult to maintain body and particularly muscle temperature from the end of the warm-up to the actual start of the different routines. Studies have, for example, shown that a high muscle temperature is essential to optimal performance during shortterm all-out exercise (Asmussen & Boje, 1945),

Corrspondence. Magni Mohr, University of Exeter, Sport and Health Sciences, St Lukes Campus, Heavitree Road, Exeter EX1 2LU, UK. Email: [email protected] © 2013 Taylor & Francis

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and it is well-known that muscle temperature declines rapidly after exercise (Mohr, Krustrup, Nybo, Nielsen, & Bangsbo, 2004). Thus, it is valuable to determine the fluctuations in muscle temperature during a trampoline gymnastics competition. Since all the jumps are maximal or near maximal dynamic explosive contractions, the metabolic load is expected to be high and potential neuromuscular fatigue may develop during the trampoline routines, which has been demonstrated in sports characterised by a high number of explosive jumps and landings (Mohr, & Krustrup, 2013; Thorlund, Michalsik, Madsen, & Aagaard, 2008; Zebis et al., 2011) and protocols using repeated countermovement maximal jumps (Twist & Eston, 2005). The high number of maximal jumps and landings in trampoline gymnastics include powerful eccentric contractions, and muscle damage may occur, which for example has been shown after drop-jumps (Kamandulis et al., 2011), high resistance training (Doncaster & Twist, 2012) and team sports having a large eccentric component (Krustrup et al. 2011). This may negatively affect performance in the last stage of the competition, and may also affect the recovery process after competition and training. In several sports, simulated protocols have been trialled to investigate physiological demands, physical performance and fatigue development (Bendiksen et al., 2012; Malan, Dawson, Goodman, & Peeling, 2010; Thorlund et al., 2008; Zebis et al., 2011). This research approach enables the study of physical loading and physiological responses in a controlled environment. Thus, the aim of the present study was to describe the activities performed, as well as physiological response and fatigue development during and after a competitive trampoline gymnastic competition. Therefore, a simulated trampoline competition was organised in which elite male trampoline gymnastics athletes participated. It was hypothesised that a trampoline gymnastic competition would provide high metabolic loading and cause impairment in jump performance during and after the competition, and that muscle temperature would drop to suboptimal levels in phases of the competition. Materials and methods Participants Male elite Danish trampoline athletes (n = 15) from the Danish National and youth National teams volunteered as participants in the study (age: 15–28 years; height: 1.68–1.80 m; weight: 65–78 kg). The study conforms to the code of ethics of the Declaration of Helsinki and was approved and

performed in adherence with the human subject guidelines of the Department of Exercise and Sports Sciences, University of Copenhagen, Denmark. Eight participants were included in the simulated competition and seven in a reproducibility test of the 20 maximal trampoline jump test. Experimental design To examine activity patterns, physiological demands and fatigue patterns in competitive trampoline gymnastics, a simulated trampoline competition was conducted, where physical performance as well as the physiological responses were assessed before (at baseline), during and after the competition. In addition, measurements were performed in the recovery period after the competition. Procedures The gymnasts reported to the Danish Sports Elite Centre (Team Denmark) two hours prior to the experiment. The first test day was the simulated competition organised as a one-day individual competition consisting of a preliminary round and a final round. The preliminary round consisted of two trampoline routines (referred to as Exercise 1 and Exercise 2) separated by the time (25 min) it took to complete the first routine and the physiological testing and then the second routine (Figure 1). After the preliminary round there was a one-hour lunch break (which is similar to a real competition timetable) followed by a final round similar to the second routine (Exercise 3). Before the preliminary round there was a one-hour warm-up and prior to the final a 40-min warm-up period (Figure 1). The warm-up included floor exercises consisting of running, jumping and various gymnastic-specific movements, which is a standard procedure prior to competition. After each warm-up there was a 10-minute break and then a march in, presentation and a 30 s one-touch warm-up on the trampoline. This is similar to how a typical trampoline competition is organised. Trampoline routines The routines in the simulated trampoline competition were the FIG compulsory routines (Exercise 1). The seniors (over 18 years) completed the FIG A routine and the juniors (under 18 years) completed the FIG B routine. All participants did a second routine that they would normally do in an official competition (Exercise 2), as well as the final routine (Exercise 3) similar to the second routine. The difficulty was judged from the video recordings after the competition.

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Figure 1. Schematic illustration of the simulated trampoline gymnastic competition.

Video analysis All trampoline tests were conducted at the Danish national trampoline facility. The trampolines used were EUROTRAMP grandmaster exclusive 4 × 6 identical to the trampolines used for 2004 and 2008 Olympic Games. The same trampoline was used for all tests to ensure inter-test reliability. The camcorder was placed 5 m away at the side and perpendicular to the middle of the trampoline at a height of 2.5 m to ensure optimal image capture. The camcorder was a pal Panasonic DV 500 with 25 Hz recording speed. The time analysis was made offline using a personal computer with Panasonic Motion DV STUDIO for DV software. In addition, the number of jumps, as well as forward and backwards rotations and twists, were quantified. All video analyses were performed by the same experienced observer.

Trampoline and countermovement jump height In competitive trampoline events it is common to use jumping height as a training parameter. One way of measuring the jumping height is to measure the time of flight plus the time in the trampoline bed during 20 maximal trampoline jumps from a standing position. No previous attempt to assess the reproducibility of this test procedure has been undertaken. In this study all time measurements were made using video with subsequent analysis on a personal computer. As this is a routine procedure, all gymnasts were familiar with the test prior to the experiment. The reproducibility of the 20 maximal trampoline jump tests was evaluated in seven gymnasts on three different training days separated by one week. The warm-up before the reproducibility tests was warm-up 1, including a few turns to get accustomed to the trampoline. This warm-up was the same for all participants prior to all testing days. All participants used the same trampoline and the jumping time was measured from the moment of the first to the

20th touchdown. In order to compare the first 10 with the last 10 jumps these were also analysed separately. The 20 maximal trampoline jump test had a very high reproducibility with average Coefficient of variation (CV) values of 0.1% for the first compared with the second and the second compared with the third test, with nearly perfect correlations (r = 0.99) for all test– retest comparisons. The participants in the simulated trampoline competition (n = 8) performed three maximal countermovement jumps (CMJs) on a jumping mat (Newtest Powertimer System, Oulu, Finland) interspersed by 10 s in the CMJ test, with the highest jump representing the test result. All countermovement jumps were done with the hands fixed at the hips as previously described (Mohr et al. 2010; Mohr & Krustrup, 2013). The participants carried out the CMJ and the 20 maximal trampoline jump test after warm-up 1 (baseline), after Exercise 2, immediately after Exercise 3 and at 24 and 48 h post-competition. The CMJ test was also performed after Exercise 1. The participants were familiarised to the CMJ test prior to the experiment. Heart rate The heart rate was recorded during the STC (n = 8) using Polar Vantage NV chest belt monitor weighing ~100 g (Polar Electro Oy, Kempele, Finland) during the entire competition. The participants’ HRmax was assessed prior to the experiments by using the Yo-Yo Intermittent Recovery test, level 1, as described by Krustrup et al. (2003). Blood samples The participants (n = 7) had a flexible venflon catheter (18 gauge, 32 mm) placed in the antecubital vein in the right forearm 30 min prior to the warm-up. Blood samples were drawn prior to and within 10 s after the completion of all trampoline routines, in a

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disposable 5 ml syringe with heparin and were immediately centrifuged and the plasma was collected and stored on ice for later analysis. 100 ml blood was hemolysed in 100 ml cooled Triton-X 100 buffer and analysed for lactate and glucose using an YSI2300 lactate analyser within 4 hours after the completion of the completion. The plasma was frozen and stored for later analysis of fatty free acids (FFA), ammonia (NH3) and K+ using a Hitachi 912 Automatic Analyzer (Roche Diagnostics, Germany), as described by Mohr, Nielsen, & Bangsbo, (2011). Blood samples were drawn at rest, after the first warm-up, before and after each competition routine (Exercises 1, 2 and 3), 5 min after the final routine (Exercise 3) and post-24 and 48 hours. Plasma from samples taken at baseline as well as 0, 24 and 48 h post competition was analysed for creatine kinase by the use of Roche kits on a Hitashi 912 Automatic Analyzer (Roche Diagnostics, Basel, Switzerland) (see Bendiksen et al., 2012).

order to achieve an optimal height and the functional part was 18.1 ± 0.4 s. The corresponding values were 34.8 ± 1.8, 15.1 ± 0.9 and 17.7 ± 0.3 s, respectively, for Exercise 2 and 35.1 ± 1.5, 15.5 ± 1.0 and 18.0 ± 0.5 s for Exercise 3. In the functional part of Exercise 1 there were 5.3 ± 0.5 forwards rotations, 6.6 ± 0.7 backwards rotations and 4.3 ± 1.1 twists, with the corresponding values for Exercises 2 and 3 being 8.4 ± 1.4, 7.8 ± 1.1 and 6.8 ± 1.2, respectively. Total trampoline time (including trampoline warmup) was 447.5 ± 41.9 s with 164.2 ± 34.8 s spent on start jumps, 140.2 ± 15.2 s on somersaults and 142.2 ± 14.1 s on stop jumps. When including the floor warm-up the total number of jumps was 252 ± 16, including 44 ± 8, 33 ± 8, 2 ± 1 jumps with single, double and triple somersaults, respectively. A total of 47 ± 16 jumps included twists, while the remaining jumps were without any rotations.

Muscle temperature measurements

CMJ height was 40.1 ± 1.2 cm before the competition, but was lowered (P < 0.05) by 3.8, 5.2 and 4.2% after Exercises 1, 2 and 3, respectively, in comparison to baseline (Figure 2(a)). After 24 h, CMJ performance was 4.8% lower (P < 0.05) than at baseline, while no difference was recorded after 48 h (Figure 2(a)). In the 20 maximal trampoline jump test total jumping time was 38.69 ± 0.58 s at baseline and did not change during the competition or in the recovery period (Figure 2(b)). Total jumping time during the first ten jumps in the 20 maximal trampoline jump test was 18.51 ± 0.22 s at baseline, which was shorter (P < 0.05) after the preliminary round (18.40 ± 0.22 s). In addition, jumping time was ~1% shorter (P < 0.05) during the initial ten jumps in the 20 maximal trampoline jump test performed 24 h after the competition in comparison to baseline (Figure 2(b)).

Muscle temperature was measured in the musculus vastus lateralis with a needle-thermistor (Radiometer, Glostrup, Denmark) that was inserted 3 cm perpendicular to the muscle as previously described by Mohr et al. (2004, 2010, 2012). Measurements were made at rest, before Exercise 1 and 2, immediately after the second warm-up, and immediately prior to Exercise 3 in six of the eight subjects. Statistical analyses Values are presented as means ± SEM. Normality was assessed using the Shapiro-Wilk normality test. Differences in 20 maximal trampoline jumps and CMJ performance, as well as muscle temperature and blood and plasma metabolites, were determined using a one way ANOVA test with repeated measurements. If a significant difference between time periods was found, a Tukey post hoc test was used to identify the points of difference. Coefficient of variation (CV) was used to measure intra-individual variations within test–retest trials of the 20 maximal trampoline jump test and was calculated as the standard deviation of the test– retest difference divided by the mean and multiplied by 100 (Atkinson & Nevill, 1998). The significance level was set at P < 0.05. Results Activity profile The exercise time in Exercise 1 was 36.0 ± 1.0 s of which the initial 16.1 ± 1.3 s was used on start jumps in

Jump height

Muscle temperature The quadriceps muscle temperature was 36.0 ± 0.2ºC at baseline and increased (P < 0.05) to 39.0 ± 0.2ºC after the first warm-up period (Figure 3). Prior to Exercise 2 the muscle temperature was lowered (P < 0.05) by ~1°C, but rose (P < 0.05) to 38.9 ± 0.1ºC after the second warmup period, but declined (P < 0.05) again prior to Exercise 3 (Figure 3). Blood and plasma metabolites The blood lactate concentration at baseline was 1.1 ± 0.1 mmol · l−1, and increased (P < 0.05) to 3.5 ± 0.3 mmol · l−1 after the first warm-up period. Blood lactate increased (P < 0.05) during Exercises 1,

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Figure 2. Counter-movement jump height (A) and 20 maximal trampoline jump test performance (B) before, during and after the simulated trampoline gymnastic competition (n = 8). Values are presented as mean ± SEM. *:Significantly different from baseline (P < 0.05).

2 and 3 with the peak values (6.1 ± 0.6 mmol · l−1) being reached 5 min after Exercise 3 (Figure 4(a)). Blood glucose was 4.5 ± 0.4 mmol · l−1 at baseline and rose (P < 0.05) to 5.7 ± 0.2 mmol · l−1 after the first warm-up interval and remained elevated (P < 0.05) throughout the experiment with a peak value of 6.2 ± 0.2 mmol · l−1. Plasma K+ was 3.6 ± 0.1 mmol · l −1 at baseline, and increased (P < 0.05) during Exercises 1, 2 and 3 compared with pre-exercise values (Figure 4(a)) with the peak value being 6.0 ± 0.2 mmol · l−1. Plasma NH3 was 53 ± 5 µmol · l−1 at baseline and rose during Exercise 1 (90 ± 12 µmol · l−1, Figure 4 (b)). Plasma NH3 increased (P < 0.05) further from

pre- to post–Exercises 2 and 3. Peak plasma NH3 was 92 ± 10 µmol · l−1. Plasma FFA was 147 ± 41 µmol · l −1 at rest and rose (P < 0.05) before and after Exercise 2 (Figure 4(b)). Heart rate Average heart rate during simulated trampoline competition was 125 ± 4 bpm corresponding to 65% of HRmax. The peak values reached during Exercises 1, 2 and 3 were 183 ± 5, 187 ± 3 and 187 ± 3 bpm, corresponding to 95, 97 and 97% of HRmax.

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Figure 3. Muscle temperature (n = 6). Values are presented as mean ± SEM. *:Significantly different from Pre Exercise1. #: Significantly different from post warm-up 2 (P < 0.05).

Figure 5. Plasma creatine kinase (CK) before and 0, 24 and 48 h after a simulated trampoline competition (n = 7). Values are presented as mean ± SEM. *:Significantly different from baseline (P < 0.05).

simulated competition (Figure 5). After 24 h plasma creatine kinase was still elevated compared with baseline (225 ± 45 U · l−1), but had returned to baseline levels after 48 h. Discussion

Figure 4. Blood lactate and plasma potassium (A), plasma ammonia (NH3) and plasma free fatty acids (B) at baseline and during the simulated trampoline gymnastic competition (n = 7). Values are presented as mean ± SEM. *:Significantly different from baseline (P < 0.05).

Plasma creatine kinase Plasma creatine kinase was 144 ± 30 U · l−1 before and increased (P < 0.05) to 217 ± 49 U · l−1 after the

The present study is the first to determine physical activities performed, as well as to characterise the physiological responses and fatigue patterns during a simulated trampoline gymnastics competition. The main findings were that countermovement jump performance and trampoline-specific jump ability were impaired during the competition, as well as 24 h post-competition. In addition, aerobic and anaerobic energy systems are taxed during the short and intense trampoline routines. Additionally, marked decreases occurred in muscle temperature in periods of the competition, which is likely to negatively affect jump performance during the trampoline routines. Finally, plasma creatine kinase was elevated immediately after and during the first 24 h after a trampoline gymnastics competition in well-trained elite athletes, suggesting the presence of muscle damage. The activity analysis that solely quantified different trampoline-specific discrete skills and timed the routines revealed that trampoline gymnasts perform more than 250 explosive jumps during competition, of which ~30% involve powerful rotations with explosive upper body movements. As a consequence, the total load of competitive trampoline gymnastics is high, which is evident from the physiological response to the simulated competition. Indeed heart rate responses during the three routines exceeded 95% of the maximal heart rate, which is even higher than reported in a simulated artistic gymnastic competition using all six Olympic

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Physiological demands in trampoline gymnastics disciplines (Goswarni & Gupta, 1998) and during a ball routine in rhythmic gymnastics (Guidetti, Baldari, Capranica, Persichini, & Figura, 2000). Considering the short duration of the trampoline routines the peak heart rate response was surprisingly high, which probably reflects the high intensity wholebody movements during the jumping phase as well as the flight phase, which include a substantial amount of static exercise in order to maintain aerial balance and correct body position. The blood lactate levels were moderately high, reaching peak values above 6 mmol · l−1. This is in line with findings by others (Goswarni & Gupta, 1998) during simulated competitive artistic gymnastics (range 2–12 mmol · l−1), but higher than in rhythmic gymnastics (~ 4 mmol · l−1; Guidetti et al., 2000). The blood samples in the present study were drawn from an antecubital vein immediately after the routines (within 10 s), but there is a delay in peak blood lactate after an intense exercise bout (Krustrup et al., 2003). Hence, based on blood lactate accumulation rates from skeletal muscles after intense exercise (Bangsbo et al., 1992; Krustrup et al., 2003), it is likely that blood lactate values may have reached ~10 mmol · l−1, if the samples had been taken 2–3 min after the routines. Thus, the activation of the glycolytic pathway is high during a trampoline gymnastics competition. Countermovement jump performance was impaired by 4–5% after all three routines (Exercises 1–3) indicating development of fatigue. In addition, the jumping time during the first ten jumps of the 20 maximal trampoline jump test fell after Exercise 2, also indicating deterioration in trampoline-specific jump performance, which is likely to compromise performance. The observed reduction in jumping time in the first ten jumps and not the last ten, may reflect the fact that the initial jumps are the most demanding ones in which the gymnasts tries to achieve an optimal height prior to the functional sequences. Jump performance has also been shown to be reduced post-competition in other intermittent sports (Mohr et al., 2010; Mohr, & Krustrup, 2013). A recent study on team handball, which includes a high number of maximal and near-maximal jumps (Povoas et al., 2012), demonstrated an acute impairment of maximal voluntary contraction, and rate of force development with concomitant reduction in quadriceps muscle EMG activity after a competitive game (Thorlund et al., 2008), indicating acute neuromuscular fatigue after intermittent sports that encompass a high number of explosive jumps. Taking into account the short exercise duration and characteristics of the routines in trampoline gymnastics, muscle lactate concentrations are not expected to be critically high compared with short-term repeated all-out exercise bouts (see for example Gaitanos, Williams, Boobis, & Brooks, 1993; Mohr et al.,

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2007). It has been shown in intense intermittent exercise protocols that the blood lactate values are higher at a given muscle lactate concentration compared with continuous exercise (Krustrup et al., 2006). In addition, muscle lactate and the associated muscle acidification has been questioned as the direct cause of fatigue during intense intermittent exercise protocols (Bangsbo et al., 1992; Krustrup et al., 2003). A potential cause of fatigue during the simulated trampoline gymnastic competition may be electrical disturbances over the sarcolemma induced primarily by potassium accumulation in the muscle interstitium (Mohr et al., 2011). In the present study, peak K+ was 6.0 mmol · l−1, which is similar to values seen at exhaustion in several studies assessing a variety of intermittent sporting activities (Bendiksen et al. 2012; Krustrup et al., 2003; 2006; Mohr, Rasmussen, Drust, Nielsen, & Nybo, 2006; Mohr et al., 2007). Thus, it is possible that ion perturbations in the active muscles play a role in impairment of acute performance during a trampoline gymnastics competition. Plasma ammonia was shown to be elevated after the three routines, indicating activation of the AMP deaminase reaction, which is supported by numerous studies using both prolonged submaximal (Nybo, Dalsgaard, Steensberg, Møller, & Secher, 2005; Parkin, Carey, Zhao, & Febbraio, 1999) and intense intermittent (Krustrup et al., 2006; Mohr et al., 2006; 2007; 2011) exercise regimes. Ammonia is mainly cleared via the kidneys and the liver (Rowell, Blackmon, Martin, Mazzerella, & Bruce, 1965), but can also cross the bloodbrain barrier (Dalsgaard, Volianitis, Yoshiga, Dawson, & Secher, 2004) causing ammonia to accumulate in the cerebrospinal fluid (Nybo et al., 2005). Exercise-induced hyperammonemia has been suggested to provoke central fatigue due to disturbances of cerebral neurotransmitter homeostasis and concomitant cerebral dysfunction (Mohr et al., 2006; Nybo, & Secher, 2004; Suarez, Bodega, & Fernandez, 2002). However, ammonia levels were relatively low in the present study with peak values being 2–4 times lower in comparison to levels observations during exhaustive intermittent exercise (Krustrup et al., 2003; Mohr et al., 2011). Moreover, the exercise bouts in the trampoline competitions were only ~40 s long, which would cause only moderate temporary increases in systemic ammonia concentration, and so be unlikely to exhaust the ammonia removal in cerebral regions. Taken together, fatigue during trampoline gymnastics may be related to an accumulated response involving peripheral as well as central physiological mechanisms, which future studies applying more sophisticated research methods will explore further.

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Countermovement jump ability as well as performance in the first ten jumps of the 20 maximal trampoline jump test had not recovered 24 h after the simulated competition, but both were restored to baseline values after 48 h. A similar pattern was observed in plasma creatine kinase, which was elevated immediately after and 24 h post-competition compared with baseline, but recovered after 48 h. This is comparable to findings by Twist and Eston (2005), who reported a marked reduced intense intermittent exercise capacity immediately after and 24 h after a series of 10 × 10 maximal countermovement jumps. In addition, markers of exerciseinduced muscle damage were elevated. Thus, due to the large number of explosive jumps and landings in competitive trampoline, a significant degree of muscle damage may occur, which can cause impairment in jump ability during the final routine, and an incomplete recovery during the first 24 h post-competition. Plasma creatine kinase was elevated by 51 and 56% after the competition and after 24 h of recovery, respectively, compared with baseline, which confirms findings after repeated maximal jumps (Twist & Eston, 2005), but is slightly lower than observed after competitive football (Andersson et al., 2008). Although the degree of muscle damage does not appear be as severe as in team sports, it may play a role in the observed reduction in performance after competition and in the early phase of recovery. High muscle temperatures (39–41°C) appear to be essential for optimal performance during explosive exercise (Asmussen, & Boje, 1945; Mohr et al., 2004). In the present study quadriceps muscle temperature increased by 3°C after the first warm-up period, reaching 39°C prior to Exercise 1, which is close to optimal for intense exercise performance (Asmussen, & Boje, 1945). However, the muscle temperature was lower before Exercises 2 and 3 due to the relatively long gap between the warm-up and the latter two exercise bouts (see Figure 1). Clearly the second warm-up produced a similar increase in muscle temperature as the first warmup, but a marked decrease occurred before the start of Exercise 3. This is supported by findings from soccer games, where a 1.5°C decline in quadriceps muscle temperature has been reported during the 15 min half-time period (Mohr et al., 2004). Therefore, reduced jumping performance after Exercises 2 and 3 may be associated with sub-optimal muscle temperature. In conclusion, this study demonstrated that the high number of explosive jumps that elite trampoline gymnasts carry out during competition elicit high aerobic and anaerobic energy demands, and result in fatigue during the competition and a relatively slow post-competition recovery.

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