Introduction
A knowledge of the metabolic contributors to performance is an essential prerequisite for a successful training prescription. Furthermore, training specificity has been reported to be a key factor in performance development in individual sports (21 4,5,20 7,11,26 17
Olympic flat water kayaking takes place in the form of 500- and 1,000-m races (until the Olympic games of Beijing [China] in 2008). It was reported that in flat water kayaking highly trained subjects spend the majority of their race time exercising at or around O2 peak (2 2,9,25 25
Although the metabolic demands of 500- and 1,000-m races have been the object of scientific scrutiny, they were mainly from laboratory simulations. In nautical conditions, to the best of our knowledge, only Zamparo et al. (25 n = 5) and female (n = 3) subjects, aged 15–32 years, who were not all competing at a high international level. Hence, the events (250, 500, 1,000, and 2,000 m) took place on the same day separated by 2 hours of rest. Thus, the aerobic and anaerobic energy system contributions to kayak events remains to be clarified depending on the gender, age, and expertise level of the kayakers. It could be hypothesized that examining the energy demands of 500- and 1,000-m flat water kayaking in nautical conditions for a specific class of athletes may lead to a better understanding of race demands and improved training prescription. Information in this regard would be helpful in profiling the anaerobic contribution across the race time and thus describing the real-life nature of time-trial race in open water kayaking.
Interestingly, kayak paddlers only rarely specialize in one of these races, and consequently, they share their training time for the development of aerobic and anaerobic pathways with no focus or limited focus on specific race demands. This is so despite the remarkable differences occurring in race time and estimated metabolic demands (25
Therefore, this study was designed to profile the aerobic and anaerobic energy system contributions to 500- and 1,000-m kayaking races in highly trained male athletes in nautical conditions using on-line gas exchange measurements and the AOD method (17 25
Methods
Experimental Approach to the Problem
We quantified the respective contributions of the energy systems during 500- and 1,000-m kayaking events using specific “in-race” measurements in highly trained subjects. The relative energy system contribution was calculated by the measurement of O2 during track-time trials, combined with the calculation of anaerobic energy expenditure using the AOD method. Accumulated oxygen deficit measures are generally accepted as the criterion measure of anaerobic energy expenditure as a result of flaws in the use of blood lactate concentration as a quantitative tool for the measurement of anaerobic energy supply (13
In this study, we calculated the anaerobic energy expenditure based on AOD as the primary measure. This method has its own inherent assumption and limitations (10
All the participants performed 3 kayaking sessions, using their personal standard K1 skull, between April and May on the same open water track (4-km length to avoid turns), separated by 2 days. To minimize any effects of diurnal and climatic variations, the 3 testing sessions were conducted within 2 hours of the same time of the day and under the same weather conditions (e.g., wind speed <2 m·s−1 ). The subjects were requested to refrain from vigorous activity and from consumption of tobacco and alcohol, cocoa, tea, coffee, and cola beverages for 48 hours before each test.
During the first testing session, the maximal oxygen uptake (O2 max) and maximal aerobic velocity (MAV) were measured for each kayaker. During the remaining testing sessions, the kayak paddlers were tested for 500- and 1,000-m races, using a randomized counterbalanced design and carefully reproducing conditions that are similar to those of competitions.
The anthropometrical characteristics of all kayak paddlers were determined in laboratory conditions before the first session test. Body mass was measured to the nearest 0.1 kg with a digital scale (Ohaus, Florhman Park, NJ, USA). Height was measured by means of a standing stadiometer and recorded to a precision of 1 mm. A recently calibrated Harpenden calliper (Holtain, Cross-well, United Kingdom) was used to estimate the body fat percentage (%Fat) from 4 skinfold thicknesses, according to the method of Durnin and Rahaman (8
Gas analyses were performed in field conditions using a portable lightweight (i.e., ∼740-g) gas exchange telemetric system (O2000 ®, Medical Graphics, Saint Paul, MN, USA). This system has been previously examined for validity and reliability using a cart system (Medical Graphics CPX/D) in our laboratory and by other authors (14,19 2 ), ventilation (E), amount of carbon dioxide released (CO2 ), ventilatory frequency (Freq.), and tidal volume (V T ) were recorded continuously.
Before each test, the O2 analysis system was calibrated using ambient air and 2 precision reference gases of known concentrations. Ventilatory data were averaged every 5 seconds for subsequent analysis. During the course of the experiment, the receiving unit of the O2000 ® was positioned in a motor boat, which followed the kayak paddlers during open water testing permanently. Exercise heart rate (HR) was recorded continuously with an HR monitor (Garmin forerunner 301® or forerunner 305®, Garmin International, Inc., Kansas, MO, USA). To determine blood lactate concentration ([La]b ), finger blood samples were collected 3 minutes after the end of the test and stored in 25-μL heparinized capillary tubes (Microzym-L analyzer®, SGI, Toulouse, France). Blood lactate concentration was determined enzymatically by using a lactate analyzer (Microzym, Cetrix, France).
All kayak speeds were determined using a Global Position System (Garmin forerunner 301® or forerunner 305®).
Subjects
Seven elite male kayakers volunteered to participate in this study. Their morphological characteristics and best performance are presented in Table 1 . The best performances of the participants corresponded to that in the French national level (under 23, national level 1), and they were ranked among the 20th first French kayakers. At the time of this investigation, the mean race performance of the athletes involved in this study corresponded to ∼93 and ∼95% of the current records for the 500- and 1,000-m race, respectively.
Table 1: Morphological characteristics and best performance time of the subjects.
The kayakers of this study were selected from regional centers throughout France. This group of elite kayakers were engaged in 8–10 training sessions per week for at least 5 years, and they followed a classical training program that consisted of strength, aerobic, and anaerobic fitness development.
The investigation took place in the 4–6 weeks before selective events for 2008 (i.e., precompetitive period).
Before the commencement of this study, all the athletes gave their written informed consent after a full explanation of the procedures involved in this study and the risk and benefit associated with this research design was given to them. The athletes were aware that they could withdraw from the study at anytime without associated penalties. The study was approved by the Ethical Committee of the University of Rennes Consultative Committee for the Protection of Persons Participating in Biomedical Research before the study.
Procedures
Submaximal and Maximal Graded Exercise Tests
The telemetric gas analysis system (O2000 ®, Medical Graphics), the global positioning system (GPS) device and the blood lactate analyzer were positioned on board of a pilot boat sailing alongside the subject tested. The design of the experiment is displayed in Figure 1 . The pilot boat was sufficiently remote from the kayak to avoid impeding the paddler by waves. The open water testing procedures (i.e., kayak speed and on-line gas analyses) were monitored from the controlling boat by 2 dedicated operators. A third operator was in charge of blood sampling on the controlling boat. During the first day, each subject performed 4–6 submaximal 6-minute kayaking bouts (21 2 was determined during the last 2 minutes of each submaximal bout. The relative intensity of kayaking ranged between 45 ± 5 and 85 ± 5% O2 max. The energy demands of 500- and 1,000-m kayaking trials were estimated using the linear relationship between steady-state O2 values and kayaking velocity. After 20–30 minutes of recovery, each subject performed an incremental kayaking test to determine O2 max. This maximal graded test was a nautical adaptation of the protocol proposed by Léger and Boucher (16 −1 and was increased by 1 km·h−1 every 2 minutes until exhaustion. The test pace was provided by audio cues emitted by an audio player positioned on the pilot boat with the speed checked by the GPS to ensure precise control of the kayak speed. Each subject was encouraged to exert a maximum effort. The test was stopped when the kayaker could not maintain the required velocity, and the mean value of the O2 during the last elapsed minute at this stage was used to determine O2 peak. The aachievement of O2 peak was accepted when the subjects fulfilled at least 3 of the 4 following criteria: a plateau in O2 despite an increase in the kayaking speed, a respiratory exchange ratio >1.10, a maximal HR near the predicted maximal theoretical HR (220 − age in year), a blood lactate concentration >8.0 mmol·L−1 , and the apparent exhaustion of the subjects. The MAV (in kilometers per hour) was then defined as the lowest running speed at which O2 peak occurred during the incremental exercise protocol. The actual boat speed was double checked with a GPS system fixed on the deck of the boat.
Figure 1: Setup. Conceptualization of the setup: incremental, 500- and 1,000-m kayaking tests.
Track-Kayaking Events: 500 or 1,000 m
To elicit maximal effort during the experimental kayak races (i.e., 500 and 1,000 m), the participants of this study competed against competitive-level matched kayakers to simulate real-life competitive races.
Before each race, the kayakers performed a standardized warm-up consisting of 15-minute kayaking at 60% of the MAV (controlled by the GPS and the HR monitor). After warm-up, the O2000 ® base harness was placed on the participant, and the O2000 ® system was attached to the kayaker's torso. The participant then performed four 100 m at increasing speed from 60 to 90% of the MAV. Few minutes before the commencement of the experimental races, gas measurement was initiated, and the GPS fixed on the deck of the kayak was activated. To provide real-life race conditions to the participants, all the experimental races were started with standard starting commands. All the time-trial races were recorded with a digital camera. After completion of the each time trial, O2000 ® measurement was ceased, the harness was detached from the participant, and a gentle cool-down exercise was performed.
To assess [La]b , capillary blood samples were obtained at rest ([La]b 0 ), 3 minutes after the end of the warm-up ([La]b Warm-up ), and 3 minutes after the time trial ([La]b End test ).
Calculation of Relative Energy Expenditure: Graded Exercise Test
For each subject, steady-state (breath-by-breath) O2 data were averaged over the last 2 minutes of each step (Excel 12.0). A linear regression analysis was used on the collected step test data to determine the individual O2 -velocity relationship for each subject. This analysis allowed for the calculation of AOD (measured in milliliters O2 equivalents per kilogram) for each time trial from calculating the difference between the O2 demand for the respective speed (from extrapolation of the calculated relationship) and the measured O2 cost.
Calculation of Relative Energy Expenditure: Track-Kayaking Events
For each subject, O2000 ® breath-by-breath data were aligned to exclude data that were not collected during the time trial. Based on the predicted O2 from the individual O2 -velocity relationship, O2 , speed, and time were then used to calculate the AOD component of the time trial.
This allowed for a measurement of anaerobic (AOD) and aerobic (O2 ) energy contributions throughout the kayak race and a total contribution over the whole time trial. Gastin et al. (10
Statistical Analyses
Data are reported as means and standard error (SE ). On the basis of a power analysis (desired power = 0.80 and an alpha error = 0.05), we determined that a sample size of n = 6 would be sufficient to study energy system contribution to kayaking events. Comparisons across events of relative anaerobic energy percentage contributions, AOD, [La]b , and O2 peak were made by 1-way analysis of variance. Correlation analysis was performed by means of a Spearman rank test. A value of p ≤ 0.05 was accepted as the minimal level of statistical significance. All statistical analyses were conducted using Sigma Stat 3.10 software (SPSS, Chicago, IL, USA).
Results
Physiological Parameters Determined during the Maximal Graded Test
Table 2 shows the physiological parameters determined at the end of the maximal graded kayaking test. The speed attained at the end of the test corresponds to the MAV. The subjects attained their highest O2 values during the last stage of the graded test, and this was assumed as O2 peak.
Table 2: Physiological parameters determined during maximal graded test.*
Performances and Physiological Variables Measured during the 500- and 1,000-m Test
Performances recorded for the 2 kayaking time trials are presented in Table 3 . These corresponded to 95 and 94% of the personal best performance of this population, for 500 and 1,000 m, respectively. The 500-m race was accomplished at a significantly higher speed than was the 1,000-m race (p < 0.05). The 500- and 1,000-m speeds corresponded to 107 and 102% of the MAV of the kayakers, respectively. Blood lactate values determined at the end of the 500-m race resulted in being significantly higher than those determined at the end of the 1,000-m race (p < 0.05). The heart rate values recorded at the end of the 2 kayaking races were not significantly different.
Table 3: Measured parameters during the 500- and 1,000-m test.*†
Aerobic and Anaerobic Energy Contributions during 500- and 1,000-m Time Trials
Aerobic and anaerobic energy contributions calculated from the AOD method for the 2 whole races are shown in Table 4 . The AOD calculated for the 500-m race was significantly higher than that for the 1,000-m race. The anaerobic energy contribution resulted in being significantly higher during the 500-m race than that during the 1,000-m race (p < 0.05). Consequently, the aerobic energy contribution was found to be significantly lower during the 500-m race than during the 1,000-m race (p < 0.05).
Table 4: Total energetic contributions during 500- and 1,000-m whole time trial.*†
Figure 2 shows the evolution of the aerobic contribution (AOD method calculation) throughout the duration of the kayaking 500 and 1,000 m. During the first 45 seconds, the aerobic and anaerobic profiles were almost identical between the 2 kayaking races. From the 30th second, aerobic contribution reaches a maximum in both race conditions. From the 45th second, the 1,000 m became more aerobic than did the 500 m although the difference was not significant.
Figure 2: Aerobic energy contribution to the 500- and 1,000-m kayaking. The evolution of the aerobic energy contribution to 500- and 1,000-m kayaking activities was determined from the calculation of the accumulated oxygen deficit component throughout each test. Data are presented as a percentage of the total energy used for each test.
Discussion
This is the first study that examined the energy system demands during 500- and 1,000-m races in elite kayakers under field conditions. This study results showed the relevance of the aerobic pathway for the investigated races with aerobic contribution being significantly higher for the 1,000-m race.
The O2 peak values of the elite kayak paddlers examined in this study are particularly high compared with the average of the worldwide elite kayaking reported in several previous studies (for review, see [18 2 peak in kayakers (i.e., laboratory conditions vs. track-kayaking events). In fact, in our study, we used a portable gas analyzer system to determine O2 peak in nautical conditions, and kayakers used their own boat, which allowed them to be more invested than they may do on a kayak ergometer in a laboratory setup. In this study, the O2 peak values are also higher than those reported by Zamparo et al. (25 −1 ·kg−1 ). These differences may be partly explained by gender differences and/or by the competitive level of kayakers involved (2,25
The results of this study indicate a predominance of the aerobic supply during the 2 races. However, it is important to note that the aerobic contribution was significantly higher during the 1,000 m compared with those during the 500 m. Indeed, the aerobic contribution expressed as a fraction of O2 peak was 78 and 86% for the 500 m and for the 1,000 m, respectively. These data are comparable with the 73 and 85% reported in middle- to high-class kayakers during 500- and 1,000-m races test in nautical conditions (25 25 24
Interestingly, the findings of this study are in line with those reported in Athletics by Duffield et al. (6,7
The different aerobic contributions between the 500 and the 1,000-m kayaking races may be related to the kayaking velocity that, because of a longer duration, is lower during the 1,000 m as compared with that in the 500 m. Indeed, the higher AOD calculated during the 500 m can be explained by a higher involvement of the anaerobic glycolysis pathway during the first few seconds of the trial. These findings are in accordance with those of Bishop (2 9
The interaction and the involvement of the metabolic pathways for the supply of adenosin-tri-phosphate (ATP) can also be described using the concept of “crossover point” (3 Figure 2 , during the first 45 seconds, the aerobic and anaerobic distributions are almost identical between the 2 kayaking races. Whatever the distance, the involvement of anaerobic exercise is predominant at the beginning of the race and then decreases (i.e., after ∼45 seconds) to become almost exclusively aerobic (1
These data support those of Zamparo et al. (25 4,21
Performances were lower than personal best-recorded performances (95% for 500 m and 94% for 1,000 m). This can be explained by the fact that the experiment took place in the precompetitive period (4–6 weeks before selective events for Olympic game, 2008).
Blood lactate concentrations may provide an indication of the extent of anaerobic glycolysis and reaches peak values after the end of submaximal or maximal exercise (12,13,15 11 26
Whatever the distances, lactate variations between rest and the end of the test (18% for 500 m and 14% for 1,000 m) were greater than those found in other kayak studies (22,23 26 15 23
In conclusion, this study has shown that whatever the distance (500 or 1,000 m), the involvement of the anaerobic pathway was predominant at the beginning of the race to decrease thereafter to become almost exclusively aerobic in the last stage of the competition. However, the aerobic contribution during the 1,000 m was significantly higher compared with that of the 500-m kayaking events.
Practical Applications
The results from our study clearly demonstrate that the 500 and 1,000 m are 2 physiologically different kayaking events suggesting race-related training programs. This information will help the trainers and coaches to program the ratio between aerobic and anaerobic training sessions with more efficiency. Although the 500- and 1,000-m training will have to be principally aerobic, coaches and trainers should not neglect the anaerobic system. The focus of the training program aiming to enhance the anaerobic energy participation for both 500 and 1,000 m should consider using weightlifting and sprint training. Athletes who are specialists in the 1,000 m must possess a higher maximal aerobic power.
Acknowledgments
The authors would like to thank all the athletes for their participation in this study. Our thanks also go to the “Pole France canoe kayak de Rennes” for their assistance.
References
1. Bangsbo, J, Gollnick, PD, Graham, TE, Juel, C, Kiens, B, Mizuno, M, and Saltin, B. Anaerobic energy production and O
2 deficit-debt relationship during exhaustive exercise in humans.
J Physiol 422: 539–559, 1990.
2. Bishop, D. Physiological predictors of flat-water kayak performance in women.
Eur J Appl Physiol 82: 91–97, 2000.
3. Bouchard, C, Taylor, AW, and Simoneau, J. Testing anaerobic power and capacity. In:
Physiological Testing of the High Performance Athlete . J.D. MacDougall, H.A. Wenger, and H.G. Green, eds. Champaign, IL: Human Kinetics, 2004.
4. Duffield, R and Dawson, B. Energy system contribution in track running.
New Stud Athl (IAAF) 18: 47–56, 2003.
5. Duffield, R, Dawson, B, and Coodman, C. Energy system contribution to 100-m and 200-m track running events.
J Sci Med Sport 7: 302–313, 2004.
6. Duffield, R, Dawson, B, and Coodman, C. Energy system contribution to 400-m and 800-m track running.
J Sports Sci 23: 299–307, 2005.
7. Duffield, R, Dawson, B, and Coodman, C. Energy system contribution to 1500-m and 3000-m track running.
J Sport Sci 23: 993–1002, 2005.
8. Durnin, J and Rahaman, M. The assessment of the amount of fat in the human body from measurements of skin fold thickness.
Br J Nutr 21: 681–689, 1976.
9. Fernandez, B, Perez-Landuce, J, Rodriguez, M, and Terrados, N. Metabolic contribution in Olympic kayaking events.
Med Sci Sport Exerc 27: S24, 1995.
10. Gastin, PB, Costill, DL, Lawson, DL, Krzeminski, K, and McConnell, GK. Accumulated oxygen deficit during supramaximal all out and constant intensity exercise.
Med Sci Sport Exerc 27: 255–263, 1995.
11. Gupta, S, Goswami, A, and Mukhopadhayay, S. Heart rate and blood lactate in 400 m flat and 400 m hurdles running: A comparative study.
Ind J Physiol Pharmacol 43: 361–366, 1999.
12. Hirvonen, J, Nummela, A, Rusko, H, Rehunen, S, and Härkönen, M. Fatigue and changes of ATP, creatine phosphate, and lactate during the 400 m sprint.
Can J Sports Sci 17: 141–144, 1992.
13. Hirvonen, J, Rehumen, S, Rusko, M, and Härkönen, M. Breakdown of high energy phosphate compounds and lactate accumulation during short supramaximal exercise.
Eur J Appl Physiol 56: 253–259, 1987.
14. Kautza, BC, Kastello, GM, and Sothmann, MS. Validation of MedGraphics VO
2000 portable metabolic analyzer and a modified pneumotachometer.
Med Sci Sport Exerc 36: S222, 2004.
15. Lacour, JR, Linossier, MT, and Barthélémy, JC. Post-competitions blood lactate concentrations as indicators of anaerobic energy expenditure during 400 m and 800 m races.
Eur J Appl Physiol 61: 172–176, 1990.
16. Léger, L and Boucher, R. An indirect continuous running multistage field test, the university of Montréal track test.
Can J Appl Sports Sci 5: 77–84, 1980.
17. Medbø, JI, Mohn, AC, Tabata, I, Bahr, R, Vaage, O, and Sejersted, OM. Anaerobic capacity determined by maximal accumulated O
2 deficit.
J Appl Physiol 64: 50–60, 1988.
18. Michael, JS, Rooney, KB, and Smith, R. The metabolic demands of kayaking: A review.
J Sports Sci Med 7: 1–7, 2008.
19. Olson, TP, Tracy, JE, and Dengel, DR. Validity of a low flow pneumotach and portable metabolic system for measurement of basal metabolic rate.
Med Sci Sport Exerc 35: S143, 2003.
20. Spencer, M, Bishop, D, Dawson, B, and Goodman, C. Physiological and metabolic responses of repeated-sprint activities: Specific to field-based team sports.
Sports Med 35: 1025–1044, 2005.
21. Spencer, MR and Gastin, PB. Energy system contribution during 200- to 1500-m running in highly trained athletes.
Med Sci Sport Exerc 33: 157–162, 2001.
22. Tesch, PA. Physiological characteristics of elite paddlers.
Can J Appl Sports Sci 8: 87–91, 1983.
23. Tesch, PA and Lindeberg, S. Blood lactate accumulation during arm exercise in world class kayak paddlers and strength trained athletes.
Eur J Appl Physiol Occup Physiol 52: 441–445, 1984.
24. Tesch, PA, Piehl, K, Wilson, G, and Karlsson, J. Physiological investigations of Swedish elite canoe competitors.
Med Sci Sport Exerc 8: 214–218, 1976.
25. Zamparo, P, Capelli, C, and Guerrini, G. Energétics of kayaking at sub maximal and maximal speed.
Eur J Appl Physiol Occup Physiol 80: 542–548, 1999.
26. Zouhal, H, Jabbour, G, Jacob, C, Duvigneau, D, Botcazou, M, Ben Abderrahaman, A, and Prioux, J. Energy system contribution to 400 m flat and 400 m hurdles track running.
J Strength Cond Res 24: 2309–2315, 2010.
