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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 63  |  Issue : 1  |  Page : 15-20

Physiological stress against simulated 200-m and 500-m sprints in world-class boat paddlers


1 Department of Sports Science, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand
2 Department of Pathology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand
3 Institute of Sports Sciences, Laboratory of Exercise Biochemistry, University of Taipei, Taipei, Taiwan

Date of Submission15-Nov-2019
Date of Acceptance10-Dec-2019
Date of Web Publication7-Feb-2020

Correspondence Address:
Dr. Chia-Hua Kuo
Laboratory of Exercise Biochemistry, University of Taipei, Taipei
Taiwan
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/CJP.CJP_87_19

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  Abstract 

To characterize physiological stress response against simulated short-distance sprints among world-class paddlers. Thirteen dragon boat gold medalists performed 200-m and 500-m simulated race trials on a kayak ergometer in a randomized, counter-balanced, crossover fashion. During the 200-m and 500-m sprints, oxygen consumption (VO2) increased from 8.7 to 31.2 ml/kg/min and from 8.0 to 32.7 ml/kg/min within 60 s, respectively. A plateau of 35 ml/kg/min below maximal VO2(VO2max) (39.7 ± 6.3 ml/kg/min) was reached at 75 s during the 500-m sprint. Respiratory exchange ratio dropped from 1.21 ± 0.16 to 1.07 ± 0.12 and 1.28 ± 0.13 to 1.06 ± 0.16 at 45 s, and resurged to 1.17 and 1.28 at the end of 200-m and 500-m sprints with lactate concentration reached 13 ± 2 and 15 ± 2 mM. Aerobic energy contribution to paddling power increases from ~10% for the first 15 s to ~80% for the last 15 s during the 500-m trial. Postexercise plasma thiobarbituric acid reactive substances increased by 376% and 543% above baseline after 200-m and 500-m trials (P < 0.001, between trials), respectively, followed by quick returns to baseline in 30 min (P < 0.001). Increased plasma creatine kinase (+48%) was observed only after the 500-m trial (P < 0.001, between trials), not 200-m trial. Our data suggest that muscle damage occurred only when maximal sprinting exceeding 2 min, highlighting an importance of volume than intensity on exercise-induced muscle damage.

Keywords: Canoeing, creatine kinase, kayaking, muscle damage, oxidative stress, paddle strokes, thiobarbituric acid reactive substances


How to cite this article:
Senakham N, Punthipayanon S, Senakham T, Sriyabhaya P, Sriramatr S, Kuo CH. Physiological stress against simulated 200-m and 500-m sprints in world-class boat paddlers. Chin J Physiol 2020;63:15-20

How to cite this URL:
Senakham N, Punthipayanon S, Senakham T, Sriyabhaya P, Sriramatr S, Kuo CH. Physiological stress against simulated 200-m and 500-m sprints in world-class boat paddlers. Chin J Physiol [serial online] 2020 [cited 2020 Aug 12];63:15-20. Available from: http://www.cjphysiology.org/text.asp?2020/63/1/15/277956


  Introduction Top


Dragon boating is an official sport in Asian Games with increasing popularity. The race involves a team of 10 or 20 paddlers, a drummer, and a helmsman. Paddlers sit in pairs on fixed benches and use a single-blade paddle to propel the boat forward over distances ranging from 200-m to 2000-m during a race. Exercise pattern of dragon boat races shares some similarity with kayak and canoe, which involves with repetitive upper-body concentric muscle contractions. Scientific documentation on physiological stress response of world-class paddlers after short-distance sprint races are scarce, which is important for training optimization and pace management of athletes.[1]

Most of the exercise models using whole-body concentric muscle contractions at ~75% VO2max does not normally increase plasma creatine kinase (CK), a hallmark of muscle damage.[2] However, 1000-m[3] and 2000-m rowing tests[4] have been reported to increase plasma CK and thiobarbituric acid reactive substances (TBARS) among elite paddlers. This suggests that upper body concentric contraction-based exercise at maximal effort can also increase muscle damage. Whether short-distance boat sprinting at higher intensity but shorter duration can induce elevations in plasma CK level remains unknown. Plasma CK is commonly used by coaches to determine recovery status after training.[5] A brief elevation of oxidative stress normally occurs during muscle damage.[6]

It is generally thought that intensity is more important than duration in exercise-induced muscle damage due to higher physical stress with greater muscle fiber recruitment. During simulated 200-m and 500-m dragon boat races on an ergometer test, elite paddlers exerted average force near 65 N and performed this movement at around 86 and 77 cycles or strokes per min, respectively. During these races, peak oxygen consumption (VO2peak) ranges from 3.0–3.5 L/min to 2.8–3.8 L/min with aerobic energy contribution from 47.4%–56.8% to 60.1%–77.8%, respectively.[1] Physiological stress responses against 200-m and 500-m dragon boat races for world-class paddlers has not been documented. Therefore, this study was designed to compare physiological stress response of world champion sprinters during a kayak ergometer test that mimics distance of 200-and 500-m races.


  Materials and Methods Top


Participants

World-class dragon boat champion paddlers (n = 13, gold medalists of 500-m event of the 28th Southeast Asian Games in 2015 and silver medalists in 200-m of the 12th IDBF World National Championship in 2015) voluntarily participated in this crossover trials at two race distances (200-m and 500-m). This study was conducted 1 month after the competition when all participants had returned to their normal living. No medical condition and antioxidant use were self-reported 1 month before the trials. Before test, participants signed their written consent form after thoroughly explanation of the procedures, requirements, associated risks, and benefits of the study by a principal investigator. The protocol of this study was approved by the Human Research Ethics Committee of Srinakharinwirot University (SWUEC/F-236/2558).

Study design

No familiarization trial is required since all participants were trained >1/week using the same testing device (kayak ergometer). Preliminary test and main test were separated by 7-10 days and conducted in the laboratory under a controlled condition (25°C ± 2°C and 50% ± 10% relative humidity). The main test included a randomized, crossover designed trials of 200-m and 500-m dragon boat simulated races on a kayak ergometer. The crossover trials were separated by 7 days under untrained condition and were conducted in the same time (08:00-10:00 a.m.) of the day to prevent diurnal variations of the participants.

Preliminary test

This test comprised physical examination and determination of VO2max and maximum heart rate (HRmax) of each participant. The physical examination measures of body weight (Tania, UM-073, Tokyo, Japan), height (Meterex II D97, UNICEF, Copenhagen, Denmark), body fat percentage (Maltron BioScan 916, Rayleigh, UK), resting blood pressure (BP), and resting HR (Omron HEM-7130, Kyoto, Japan). The measurement of body fat, BP, and HR was conducted after the participants relaxed in a supine position for 10 min.

To determine VO2max and HRmax, participants performed a graded exercise test on an ergometer (Kayak ergometer, Weba Sport, Vienna, Austria) using canoe mode. This test was modified from a previous research,[1] which consisted of paddling at 4 submaximal stages (35, 45, 55, and 60 stroke/min). Each stage was changed to the next stage when VO2 reached plateau for 1 min. Participants were verbally encouraged to paddle at their maximum effort with consistent force on each stroke throughout the test. After the 4th submaximal stage, the participants increased stroke rate by 5 stroke/min every min, and the test was terminated when at least 3 among 5 of the following criteria were met: (1) an increase in VO2 <150 ml/min despite increasing stroke rate; (2) respiratory exchange ratio (RER) higher than 1.1; (3) an attainment of 95% of the aged-predicted HRmax; (4) rating of perceived exertion (RPE) at 18; or (5) inability to maintain the desired stroke rate despite strong encouragement. During the exercise test, pulmonary gas exchange was measured using a gas analyzer (Korr CardioCoach CO2, Utah, USA) that operated on a mixing chamber system and automatically calibrated for barometric pressure, temperature, and humidity before each test. HR was recorded using a HR monitor (Polar H7, Polar Electro Oy, Kempele, Finland). Power output (PO) of the paddling was calculated using the ergometer (Kayak ergometer, Weba Sport, Vienna, Austria), and RPE was rated on a 6–20 scale[7] before changing to the next stages. The gas analyzer, HR monitor, and ergometer were started and stopped concomitantly. VO2max and HRmax were defined as the highest average VO2 and HR, respectively, measured over the 15 s period. Average PO and VO2 for the last minute of each submaximal stage were calculated and then plotted along the x- and y-axes, respectively, with the individual's resting VO2 as the y-intercept. This created a linear regression relationship between PO and VO2 (PO-VO2 equation) that would be used to determine the energy cost of dragon boat racing in the main test.

Main test

The participants performed 2 trials to evaluate responses of muscle damage markers. These trials consisted of warm-up for 10 min, simulation of 200-m, and 500-m dragon boat racing for 54 s and 2 min 22 s (142 s), respectively, followed by a 30-min recovery [Table 1]. The warm-up included stretching activities and paddling at self-selected stroke on an ergometer (Kayak ergometer, WEBA Sport, Vienna, Austria) that had been set at a canoe device. The simulation trials of dragon boat race were initiated by having the participant in a preparation position on the ergometer and then paddling as fast as possible following the verbal signals "Are you ready", "Attention", and "Go" from the researcher. The resistance level during 200-m and 500-m simulated races is directly related to how hard (force) or fast (paddle rate) the individuals paddle by pulling the handle against the airbrake system of the ergometer. The participants were verbally encouraged to paddle at their maximal effort throughout the race with a technique typically used by their team during on-water competition. Durations of 54 s and 2 min 22 s were the average of the 5 national dragon boat teams of Thailand, Indonesia, Myanmar, Singapore, and Philippines in the final event of men's traditional boat race, 12-crew, 200-m and 500-m, officially reported in the 28th Southeast Asian Games. During recovery, the participants rested in the laboratory for 30 min, without food and fluid consumption.
Table 1: Testing procedure of simulated dragon boat races on a kayak ergometer

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The participants maintained their normal diets and physical activities throughout the test. They were asked to refrain from exercise, caffeine, and alcohol for 24 h prior to the trials. Furthermore, they recorded their physical activities and food intake for 24 h before the 1st trial and replicated these before the 2nd trial. On the trial day, they arrived at the laboratory in a rested state, fully hydrated, and at least 2 h after a light breakfast.

Mechanical and physiological measures

During the simulated trials, paddling stroke, force, and PO were measured using the ergometer (Kayak ergometer, WEBA Sport, Vienna, Austria). HR was measure using a HR monitor (Polar H7, Polar Electro Oy, Kempele, Finland). VO2 was assessed using a gas analyzer (KORR CardioCoach CO2, Utah, USA). All devices were synchronized. Data of paddling stroke, force, PO, HR, and VO2 were averaged over the trials. Data of PO and VO2 were also calculated in 15 s intervals to examine energy contribution to the races using methods presented in the previous study. Briefly, the averaged PO value of each 15 s interval was converted to VO2 using the PO-VO2 equation obtained from the graded exercise test, and the calculated VO2 of all 15 s intervals was summed. The sum of calculated VO2 of all 15 s intervals above resting value reflected the total energy cost of the mechanical work. Aerobic energy contribution was calculated by percentage of VO2 values × 5 (in calorie) above resting value against total work done (in calorie).[1],[8]

Blood analysis

Blood samples (8 ml) were taken from an antecubital vein before warm-up (Pre), immediately (0 min), and 30 min (30 min) after the trials. The blood samples were drawn while participants were in a sitting position and collected in lithium heparin tubes (Greiner Bio-One, Kremsmünster, Austria) before centrifuging (EBA 20, Hettich ZENTRIFUGEN, Tuttlingen, Germany) at 5,000 rpm for 10 min. Plasma was then separated and stored at −80°C for further analysis. CK level was quantified using enzymatic colorimetric method (Cobas 6000 analyzer series, Roche, Basel, Switzerland). TBARS concentration was measured using TBARS assay kit (R and D system, Minneapolis, USA) with the absorbance value of 532 nm. In addition, capillary blood was taken from the finger of the participants at the same intervals and immediately analyzed for lactate using an analyzer (Lactate Plus Meter, Nova Biomedical, Massachusetts, USA).

Statistical analysis

Data were presented as mean ± standard deviation. Paired t- test were used to determine differences of mechanical and physiological parameters between the trials. Two-way analysis of variance (ANOVA) with repeated measures was used to evaluate the effects of trial distance (2 levels) and time (3 levels) on lactate, CK, and TBARS levels. Significant interactive effects were followed up with paired samples t-test and one-way ANOVA with repeated measures. Post hoc comparisons were made with Bonferroni correction. Statistical significance was set at P < 0.05.


  Results Top


The experimental procedure is listed in [Table 1], which indicates the timing of blood sample collection in relation to sprints. Physical characteristics of the world-class participants are shown in [Table 2]. [Table 3] provides data on mechanical stress during 200-m and 500-m simulated dragon boat races on the kayak ergometer. Average stroke rate, force and PO were significantly higher during 200-m trial compared with the 500-m trial. During both 200-m and 500-m trials, stroke rate declined progressively [Figure 1], indicating physical fatigue by ~10% at the end of both trials. HR increased and stabilized around 1 min. Declines in stroke rate attenuated at about the same time.
Table 2: Physical characteristics of the world-class paddlers (n=13)

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Table 3: Mechanical parameters during 200-m and 500-m simulated dragon boat races on a kayak ergometer (mean±standard deviation)

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Figure 1: Paddling fatigue (declines in stroke rate) (a) occurs together with heart rate increases during 200-m and 500-m simulated race trials (b) on a kayak ergometer. *Denotes significant difference against the first 15 s, P < 0.05. Denotes significant difference against 200-m race at the same time point, P < 0.05.

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Aerobic energy contribution, estimated by oxygen consumption rate above resting level, increased from ~10% to ~45% for the first 60 s on both trials [Figure 2]. This ratio further increased to ~85% during the 500-m trial. Plasma lactate increased significantly from 1.0 mM to 13.0 (200-m) or 15.5 mM (500-m) at the end of trials and declined rapidly to 4.6 mM (200-m) and 6.5 mM (500-m) in 30 min. There were a significant interaction effect (F(2,48)= 5.442, partial η2 = 0.185, P = 0.007), main effect of time (F(2,48)= 560.117, partial η2 = 0.959, P = 0.000), and main effect of trials (F(1,24)= 9.227, partial η2 = 0.278, P = 0.006) for blood lactate levels.
Figure 2: Aerobic energy contribution to paddling power during 200-m and 500-m simulated race trials on a kayak ergometer. Aerobic energy contribution was estimated by oxygen consumption rate (1 L/min equivalent to 5 Kcal) as percentage of average power every 15 s above resting oxygen consumption level. Increased aerobic energy contribution occurred in parallel with declined stroke rate during the simulated trials. *Denotes significant difference against the first 15 s, P < 0.05.

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Plasma CK levels increased only during the 500-m trial, but not the 200-m trial [Figure 3]. Plasma CK levels were significantly increased immediately after and 30 min after the 500-m trial compared with Pre. Despite CK level declined during 30-min recovery after the 500-m trial, it remains significantly higher than that after the 200-m trial. The results of 2-way ANOVA for plasma CK levels revealed a significant interaction effect (F(2,44)= 650.268, partial η2 = 0.967, P = 0.000) and main effect of time (F(2,44)= 1278.750, partial η2 = 0.983, P = 0.000).
Figure 3: Plasma CK (muscle damage marker) increased only after 500-m trial (duration: 142 s). No change was found after 200-m trial (duration: 54.5 s). *Denotes significant difference against Pre, P < 0.05. Denotes significant difference against the 200-m race at the same time point, P < 0.05. CK: Creatine kinase.

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Plasma TBARS levels increased immediately after both 200-m and 500-m trials [Figure 4]. This increase dropped rapidly in 30 min. The 2-way ANOVA showed a significant interaction effect (F(2,48)= 54.905, partial η2 = 0.696, P = 0.000), main effect of time (F(2,48)= 847.865, partial η2 = 0.972, P = 0.000), and main effect of trial (F(1,24)= 182.468, partial η2 = 0.884, P = 0.000) for plasma TBARS levels. Plasma TBARS levels were higher after 500-m than 200-m trial.
Figure 4: Plasma TBARS (oxidative stress marker) increased after 200-m and 500-m simulated race trials. *Denotes significant difference against Pre, P < 0.01. Denotes significant difference against the 200-m trial at the same time point, P < 0.05. TBARS: Thiobarbituric acid reactive substances.

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  Discussion Top


Most of muscle contraction patterns during dragon boat paddling are concentric in nature. Concentric muscle contraction is generally considered to create negligible muscle damage, compared with eccentric muscle contraction. However, recent studies in 1000-m[3] and 2000-m rowing tests[4] have shown significant increases in plasma CK among paddlers. It remains unknown whether short-distance sprints can produce muscle damage among world-class dragon boat paddlers. Here, we found that increased muscle damage occurred only when maximal sprinting >2 min (500-m sprint). Despite the fact that intensity was higher than 500-m sprint, no CK elevation was found after the 200-m sprint. With shorter distance, immediate increases in plasma CK was substantially higher compared to previous reports after the rowing test and kayak sprint with greater distances.[3],[4] Taken together, exercise volume in addition to intensity is a major contributor for the magnitude of exercise-induced muscle damage for paddling exercise at maximal effort.

The increases in plasma CK after 500-m sprints found in this study seem to be triggered by mechanical damage. In the study, paddlers exerted a force of 117.0 ± 10.9 N and 103.7 ± 8.9 N and paddled at 74.7 ± 7.2 stroke/min and 60.3 ± 5.9 stroke/min during the 200-m and 500-m sprints, respectively. This repetitive, high frequency movements may exceed stretch threshold of the connective tissues. This is supported by a clinical study which reports commonly injured regions localized in lower back (22.1%), shoulder (21.1%), and wrist (17.3%) among paddlers during dragon boating.[9]

Increases in oxygen demand have been thought to involve with free radical production during and after exercise, which in turn contributes to muscle damage.[10] This speculation is not completely supported by our data. Despite 500-m sprint demands greater overall oxygen consumption (500-m) with greater TBARS than 200-m, it is difficult to explain why no muscle damage was observed in the 200-m with significant increases in TBARS level (oxidative stress marker). Lactic acidosis during anaerobic acidosis is another known contributor for increased oxidative stress after exercise,[11] but not necessarily a cause of muscle damage.

According to our data and others,[1] energy contribution for 200-m and 500-m distance sprints is relied mostly on anaerobic energy substrate, supported by dramatic rises in plasma lactate concentration during sprinting at both distances. RER resurge at the final stage of 500-m sprint together with high lactate level indicates that glycolysis is still a major energy source for this distance. Furthermore, VO2 during the trial was below VO2max despite the maximal effort was given. This suggests that oxygen delivering system was not yet fully in place during 500-m trial. Mechanical stress during repetitive stroke to a certain threshold might have been the major cause of muscle damage during the boating trial.

Our data indicate that exercise volume is probably crucial in addition to intensity for generating muscle damage and oxidative stress for maximal effort sports events. While the average stroke rate and power during the 500-m were lower than 200-m, greater increases in CK and TBARS were found after 500-m trial compared with the 200-m trial. This is consistent with previous report,[12] which shows similar muscle damage levels in both high- and low-intensity training when total volumes were controlled at the same level. It is worthy to note that the 500-m trial in this study lasted approximately 2.5 fold longer than the 200-m trial. Average stroke number in the 500-m trail was significantly higher than the 200-m. Therefore, greater muscle damage produced during 500-m than 200-m trials may simply follow thermodynamic principle on entropy increases.

The limitation of the study is utilization of kayak ergometer to simulate 200-m and 500-m dragon boat race. Despite that maximal effort is used for the paddlers, dragon boating is a team sport in which synchronization of the entire team is another factor that enforces the pace for each individual athlete. The important value of the study is to provide documentation on the rate of postexercise recovery in TBARS and CK. Postexercise oxidative stress (TBARS) may reflect the recovery status and predicts endurance performance. The amount of lipid peroxidation during acute bouts of exercise is associated with the exercise mode, intensity, and duration.[13] In horse, exercise increases TBARS in the 80 km race but not the 160 km race. TBARS level before competition is significantly higher in horses that failed to finish the 80 km race.[14] Therefore, the data of the study may serve as a reference allowing coach and paddlers to monitor recovery status based on both markers.


  Conclusion Top


The results of study suggest that race time above 2 min at maximal effort might be a threshold to induce significant muscle damage among world-class dragon boat paddlers. Despite the fact that intensity during 200-m sprint is higher than the 500-m sprint, the 200-m sprint at maximal effort is not sufficient to produce detectable muscle damage. Furthermore, sprinting on both distances induces a transient oxidative stress, which quickly recovered in 30 min. Exercise intensity is generally regarded as primary cause to induce muscle damage and our data highlight the importance of exercise volume in addition to intensity on muscle damage at maximal effort paddling during simulated race.

Acknowledgments

This study was supported by the Graduate School of Srinakharinwirot University. The authors express thanks to the Rowing and Canoeing Association of Thailand for permission and facilitation to conduct the study, and the paddlers from Thai National Dragon Boat Team for their participation in the study. The authors acknowledge Nutcharat Chimbanrai and Arisara Pantulap for their assistance in data collection.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Mukherjee S, Leong HF, Chen S, Foo YX, Pek HK. Injuries in Competitive Dragon Boating. Orthop J Sports Med 2014;2:2325967114554550. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555555/. [Last accessed on 2019 Dec 20].  Back to cited text no. 9
    
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Powers SK, Nelson WB, Hudson MB. Exercise-induced oxidative stress in humans: Cause and consequences. Free Radic Biol Med 2011;51:942-50.  Back to cited text no. 10
    
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Siesjö BK, Bendek G, Koide T, Westerberg E, Wieloch T. Influence of acidosis on lipid peroxidation in brain tissues in vitro. J Cereb Blood Flow Metab 1985;5:253-8.  Back to cited text no. 11
    
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Paschalis V, Koutedakis Y, Jamurtas AZ, Mougios V, Baltzopoulos V. Equal volumes of high and low intensity of eccentric exercise in relation to muscle damage and performance. J Strength Cond Res 2005;19:184-8.  Back to cited text no. 12
    
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Bloomer RJ. Effect of exercise on oxidative stress biomarkers. Adv Clin Chem 2008;46:1-50.  Back to cited text no. 13
    
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Holbrook TC, McFarlane D, Schott HC 2nd. Neuroendocrine and non-neuroendocrine markers of inflammation associated with performance in endurance horses. Equine Vet J Suppl 2010;(38):123-8.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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