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Fitness Testing Assignment: In-line Skating

Fitness Testing Assignment: In-line Skating - by Jay Chau

Introduction
Physiological Characteristics
Fitness Testing
Conclusion
References

Introduction

Since the development of modern in-line skates in 1980, in-line skating has become the fastest growing recreational sport, particularly in the US. In 1993 there was an estimated 12.6 million in-line skaters in the US. In-line skating is popular because of its affordability of equipment, the potential for aerobic exercise, and the value of the sport for both recreation and transportation. The single role of very low friction polyurethane wheels allows in-line skaters to move faster, maneuver better, and withstand greater stress loads than the traditional "quad" roller-skater. The minimal ballistic forces involved results in a low-impact endurance workout (Schieber and Branche-Dorsey 1995).

In-line speed skating or speed roller-skating is of the fastest growing disciplines in competitive skating worldwide. Speed skaters race indoors on a flat oval track measuring anywhere from 80 to 100 meters (m). They also skate on outdoor surfaces of concrete or bitumen tracks that measure from 300m and upward to 1000m. In Australia the distances that are raced are determined by age and range from 300 meters time trials to 42 kilometers marathons. Relays are also very popular events with teams of skaters trying to use their combined skills and speed to defeat the other relay teams (Doyle 1998).

The best performance times in 1999 male Australian road in-line speed skating (table 1) ranged from 25.79 seconds in the 300m race to 36:02 minutes in the 20000m race (Doyle 1998). Therefore, the energy transfer systems mainly used in the sport can be either immediate energy system (ATP-CP) in the 300m race, short-term energy system (glycolysis) in the 500m and 1000m races, or long-term energy system (aerobic) in the 10000m to 20000m races, or a combination of the three system.

Table 1. Results of 1999 male Australian road in-line speed skating championships
Race	300m	500m	1000m	10000m	15000m	20000m
Time	25.79s	45.75s	1:42min	16:58min	25:54min	36:02min

An effective fitness-testing program in the in-line speed skating is required to indicate the athlete's strengths and weakness and provides baseline data for individual training program prescriptions. Reassessment at regular periods provides the athlete and the coach with an objective basis for assessing the effectiveness of the intervening program (MacDougall and Wenger 1991).

Physiological Characteristics

A comparison of the physiological response to in-line skating with the more traditional modes of exercise training had been reported by Snyder et al (1993). They found that if a 4mM lactate concentration is used as a guide for exercise intensity, the oxygen utilization will be less for in-line skating than for running. Similarly, if heart rate (HR) is used as a guide for exercise intensity, oxygen utilization will be less for in-line skating than for running or cycling. The slope of the HR/oxygen uptake (VO₂) relationship was greater for in-line skating than for cycling or running. This finding has important implications for use of HR as a guide for exercise intensity with in-line skater. Control of exercise intensity by commonly referenced heart rate zone may result in inadequate stimuli for aerobic training with in-line skating. Therefore, it is clear that exercise heart rate based on laboratory treadmill running tests or cycle ergometer tests are not valid for in-line skating.

Fedel et al (1995) investigated the cardiorespiratory responses of 12 competitive male in-line skaters during submaximal and peak skating. The mean VO_{2 max} obtained in the subjects (53.6 ml.kg^-1.min^-1) is comparable with both that reported for competitive athletes in other events and the 53.3 ml.kg^-1.min^-1 value reported for marathon ice speed skaters tested on in-line skates (Boer et al 1987). When the skating speed at 22.5 km.hr^-1, HRmax and VO_{2 max} were 74% and 51% respectively. At 27.4 km.hr^-1, HRmax and VO_{2 max} were 85% and 72% respectively. When compared to the American College of Sports Medicine's guidelines, regression analysis revealed a leftward shift in the VO₂/HR relationship, evidenced by a disproportionately higher HR at approximately 60% vs 80% of VO_{2 max}. Hence, for persons interested in competitive in-line skating it seems appropriate to assess peak VO₂ during in-line skating. Doing so would better determine the necessary HR or velocity needed to achieve a VO₂ sufficient to improve cardiorespiratory fitness.

Both the studies by Snyder et al (1993) and Fedel et al (1995) showed varying disproportionate levels (leftward shift) in the VO₂/HR relationship. This may be due to differences in body position experienced while in-line skating to other more upright modes of locomotion (i.e., running).

In-line speed skating technique, like ice speed skating, requires the athlete to assume a "sitting" position, with respective trunk and knee angles of approximately 55° and 118° (Rundell 1996). It have been suggested that the simultaneous isometric contraction of opposing muscle groups in the hip and upper leg during the static glide phase of skating results in a reduced leg blood flow to the extensor muscles. This may alter physiologic responses in that HR is increased and both oxygen utilization and muscle lactate efflux are reduced. Finally, it may increase the dependence on anaerobic energy production (alactic and lactic energy systems) during speed skating (Fedel et al 1995, Rundell et al 1996). However, Fedel et al (1995) pointed out that muscle blood flow has not yet been measured during in-line or ice speed skating to validate this proposed mechanism.

Rundell (1996) examined the physiological responses in 7 elite male short track speed skaters during the performances in running, in-line skating in upright, and in-line skating in the "sitting" position on a motor driven treadmill on randomized days. It was found that the skating in the low position is metabolically more stressful with depressed oxygen uptake values and higher blood lactate concentrations (p< 0.05). The VO_{2 max} values during skating in either position did not approach those achieved during treadmill running, therefore, the author suggested that evaluation of speed skaters in a sports-specific laboratory test appears to be congruent with performance and demonstrates potential in addressing the unique physiological demands of the sport.

Fitness Testing

Despite the broad acceptance of this unique mode of exercise and sport, there have been only few studies so far to investigate the physiological responses related to in-line skating. And there is no study attempts to standardize the fitness testing protocol in this sport. Therefore, the following fitness testing protocols are proposed accordingly for competitive in-line speed skating athletes.

The experimental design used to investigate the cardiorespiratory responses to in-line skating were varied in the literatures and made direct comparisons difficult. Most of the measurements were conducted as field test. The principle was basically to analyze the gas samples via a gas collection apparatus wore on a shoulder harness while the subject was in-line skating (Fedel et al 1995, Wallick et al 1995), or monitored continuously via telemetry using a portable open-circuit spirometry system (Melanson et al 1996, Baum et al 1999). Heart rate was measured throughout the exercise tests using radio telemetry. Lactate concentration were determined in arterialized blood samples taken from one ear lobe before and immediately after each test run as well as few minutes afterwards. The testing included 3 to 15 minutes' duration of skating with maximal or/and submaximal efforts depending on different protocols used. Some studies were carried out indoors while others underwent in outdoor tracks (Baum et al 1999, Fedel et al 1995, Melanson et al 1996, Wallick et al 1995).

Rundell (1995) was perhaps the first one to improvise the physiological tests of speed skating in a sport-specific laboratory environment. Seven top U.S. male short-track speed skaters were tested by simulating the ice-skating action with in-line skating on the treadmill. In general, result gained from laboratory test is more reliable but is less valid than field test because field test is more sport-specific. As the researcher can control the extrinsic variables such as wind velocity, temperature, humidity, and track condition, athlete performance varies less in the laboratory setting (MacDougall and Wenger 1991). As the body position and the movement pattern between ice-skating and in-line skating are very similar, therefore, the following aerobic testing procedures are largely based and adopted from the study by Rundell (1995). However, it should be reminded that the athlete skates in a straight line in the treadmill in-line skating testing, while in the competition, there is lots of turning along the curve of the field to be tackled as well as cutting for advantage positions with other athletes.

Aerobic Test

Aerobic power is the rate at which energy is provided from aerobic metabolism, i.e., ATP is generated by oxidation of carbohydrates and triglycerides to water and carbon dioxide. Two major laboratory measurements of aerobic power are maximal aerobic power (MAP, reflected as VO_{2 max}) and lactate threshold (LT). MAP is equal to the maximum amount of oxygen that an individual can be stimulated to extract from the atmosphere and then transport to and be used in tissue. The term lactate threshold is defined as the highest exercise level or level of oxygen uptake that is not associated with an elevation in blood lactate concentration above the pre-exercise level (or an increase less than 1.0 mM). Normally, athletes who have a high MAP also have a high LT, but the relative importance of both varies depending on the event or sport in which the athletes compete. Theoretically, in longer duration or endurance events such as the 10,000-m run, the athlete's power output as LT is a better predictor of success than is MAP because the athlete must run at a rate that is very close to that of LT. On the other hand, in shorter duration aerobic events such as the 1500-m run, in which exercise intensity actually exceeds that at MAP, the athlete would benefit most from having a high MAP regardless of the LT level (Thoden 1991). Regardless of thee precise relative energy contributions, it is apparent that aerobic energy pathways are important in speed skating performance (Rundell 1996).

Laboratory Testing Procedures

Each athlete will perform incremental test on a motor driven treadmill to volitional exhaustion. The skating surface of the treadmill used is suggested of more than 2.5-3.0 meters. Oxygen uptake (VO₂) will be determined continuously during the test using open-circuit spirometry. Calibration is performed using standard gases (26% O₂balance N₂, and 16% O₂ 4% CO₂ balance N₂) and verified before each test. Heart rate will be continuously monitored using Polar heart rate monitors. At the beginning of each test, the athlete will be secured with a safety harness suspended from the ceiling (Rundell 1996), and given 3 minutes for familiarization of skating on the treadmill. Athletes will wear their own skates, however, the same set of wheels (same size, durameter and brand name) and bearings (same rating and brand name) will be chosen and used by all athletes.

The test consists of two parts. Part I is a submaximal workload which consists of four 4-min stages and begins at an inclination of 5% and a speed of 5 mph. Speed will be increased 1 mph each successive stage, while elevation remains constant. At the completion of each 4-min stage, an arterialized blood sample is taken via finger stick for lactate determination. Calibration will be verified using 2.5 and 5 mM standard lactate samples, and recalibration is performed after every four samples. After 10-min recovery the athlete performed Part II of the test, which is designed to elicit VO_{2 max}. Part II begins at an inclination of 5% and a speed of 9 mph. At the end of each minute, elevation will be increased by 1%. This procedure is continued to volitional exhaustion, or terminated when the athlete could no longer maintain pace. And it is very important that the tester has made every attempt to push the athlete to the near-limits of performance. An arterialized blood sample was taken 2 minutes post-exercise for lactate determination (Rundell 1996). Ratings of perceived exertion (RPE, 6-20) will be evaluated by each athlete immediately after completing each test condition (Fedel et al 1995).

The maximal steady state lactate and VO_{2 max} values can be obtained in the two tests. There is a large volume of research suggesting that the blood lactate response to exercise is a better indicator of endurance performance than VO_{2 max}. It is because that endurance exercise performance is directly related to the ability to use a high fraction of VO_{2 max} with minimal accumulation of blood lactate. Exercise at intensity above lactate threshold reduces endurance time due to metabolic acidosis and accelerated glycogen depletion, therefore the successful endurance athlete is often characterized by the ability to perform high amounts of work at or just below lactate threshold (Macardle et al 1996).

Although there is no normative data available as a standard of comparison in the tests, the results from Rundell (1996) can be used as a reference (table 2).

Table 2. Mean physiological parameters of seven elite male short-track speed skaters from peak performance during treadmill in-line skating in a low position (Mean trunk angle 56° and knee angle at 107°).
VO_{2 max} (ml.kg^-1min^-1)	HRmax (bpm)	Lactate (mM)	Time to Exhaustion (min)
57.2	197	11	3.5

The lactate response in the test was unfortunately presented as graph. However, by judging from the graph, at lactate level of 4mM (onset of blood lactate accumulation), the oxygen uptake of LS skating was 45 ml.kg^-1.min^-1 (Rundell 1996). When the value is normalized to percent of VO_{2 max}, % VO_{2 max} at 4 mM lactate threshold was 79% respectively.

However, it should be reminded that the above protocol was targeted to test short-track in-line speed skater, i.e., 1000 meters event. Protocol may need to be adjusted for long-track skating athlete, with the gradient of intensity in especially the test II to be lowered appropriately. Therefore, the test with adjusted protocol may reflect the performance of different event with greater specificity.

Anaerobic test

Anaerobic energy production appears to be important for performance success in ice speed skating. This concept was reflected by the extremely high power outputs on short duration cycle ergometer tests by speed skater (Rundell and Pripstein (1995). Likewise, testing of anaerobic ability is certainly useful for the in-line speed skating in determining ability to surge and sprint which may be useful in starting, advancing other competitors during the race and in the final dash of a race. Obviously, anaerobic ability is highly relevant to short-track skaters in 300 and 500-m races. Efforts of short duration and maximum intensity are highly dependent on anaerobic energy production mechanisms, however, routine testing of the anaerobic energy systems in athletes is still not a common feature of the sport science laboratory, and sport scientists are generally not as well informed in this area as in some of the other areas of athlete testing (Bouchard et al 1991).

In testing elite performers, it is impractical to attempt to assess in vivo the ATP maximum yield of the alactic and lactic anaerobic pathways and their respective precise contribution to a given maximum work output. A more realistic approach is to measure maximal work output during periods lasting from a 10-second to 30-second all-out test, where ATP replenishment depends primarily on the alactic and lactic anaerobic pathways (Bouchard et al 1991, Green 1995).

There is no study so far to evaluate the anaerobic ability in in-line or ice speed skating specifically to its typical body position and movement pattern. Despite the specificity of the test, Quebec 10-second test had been used to evaluate various athletes with different sports including ice speed skating (Serresse et al 1989 in Bouchard et al 1991).

Laboratory Testing Procedures

The Quebec 10-second test is performed on a modified Monark ergocycle. A photoelectric cell registers each third of a flywheel revolution and relays the data to a microprocessor. A potentiometer connected to the tension-adjustment mechanism of the ergocycle registers the work load. An electrical timing system controls the input to the microprocessor, and the total work performed each second is computed. Initial workload is determined according to body weight but is manually adjusted during the test so that the subject can maintain a high pedaling speed of 10 to 16 ms^-1. The test consists of two 10-s all-out trials. The subject must do the following:

Always pedal in a seated position.
At the first signal, pedal at 80 rpm while the workload is rapidly adjusted within 2 to 3 s by the investigator.
At the command "start", pedal as fast as possible for 10 seconds.

Strong verbal encouragement is given to the subject throughout the test. After the first trial and a 10-min rest period, a second trial is performed (Bouchard et al 1991).

Work output is registered in joules per kilogram of body weight (J.kg^-1) during the best 10-s performance. Power output in watts per kilogram of body weight (W.kg^-1) is computed as the highest work output in 1-s. An index of fatigue or power decline, defined as the ratio of the last second's power output divided by the second with the highest power output, can also be used. Table 3 lists the mean reference values of 7 male ice speed skater currently available tested with the Quebec 10-s test (Bouchard et al 1991):

Table 3. Mean physiological parameters of seven male short-track speed skaters with the Quebec 10-s test.
10-s work output (J.kg^-1)	Highest power output (W.kg^-1)	Fatigue index (%)
125	13.8	85

Flexibility test

Flexibility has been defined as the range of motion at a single joint or a series of joints and reflects the ability of the muscle-tendon units to elongate within the physical restrictions of the joint. Attempts have been made to differentiate static and dynamic flexibility. Static flexibility is the measurement of angular displacement of a joint's range of motion. Although it is used frequently to reflect flexibility, angular displacement is not a direct measure of muscle length or change in length. Dynamic flexibility has been associated with the opposition or resistance to joint movement. Neither a conceptual framework nor a reasonable measurement procedure for the latter term has been widely accepted, so many authors refer to flexibility as a static measure. It has been widely agreed that flexibility is important to athletic performance and injury prevention (Hubley-Kozey 1991).

Hubley-Kozey (1991) suggested that speed skating is required large ranges of motion at one or two joints but not overall flexibility at several joints. The specific joint motions include hip adduction/ abduction. It could be understood that during skating in straight line, the sliding pattern of the lower extremities performs mainly a large hip abduction action, while in turning around a curve track, the lower extremities performs a large scissors-like action, i.e., hip adduction.

Laboratory Testing Procedures

Position the subject supine, with the hip in zero degrees of flexion, extension, and rotation. The knee is extended. The examiner uses the one hand to pull the athlete's leg into abduction until a firm end-feel is appreciated. The end of the range of motion (ROM) occurs when lateral motion of the extremity causes lateral tilting of the pelvis and lateral spinal flexion. The pelvis motion is stabilized and detected by examiner's other hand. The procedure for hip adduction is the same but with the contralateral hip is abducted first. For the goniometer measurement, center the fulcrum of the goniometer over the anterior superior iliac spine (ASIS) of the extremity being assessed. Align the proximal arm with an imaginary horizontal line extending from one ASIS to the other ASIS. Align the distal arm with the anterior midline of the femur using the midline of the patella for reference (Norkin and white 1995).

The normative value of hip abduction and adduction ROM is not yet available in the literature for speed skaters. Reference from Magee (1997) indicated that, for normal population, the hip abduction is 30-50°, and hip adduction is 30°. Obviously, for competitive speed skaters, larger ROM is required.

Conclusion

There is no standardized fitness testing protocol available yet for in-line speed skating. The author attempts to formulate one comprising aerobic, anaerobic and flexibility tests specific to the sports, so as to evaluate the fitness of elite athletes and design appropriate training plans. Sport specificity of the tests maximizes validity and reliable testing procedures enable comparisons of the athletes in different places.

References

Baum K, Hoy S, Fischeer F, Leyk D, Schmidt O and Ebfeld D (1999): Comparison between the physiological response to roller skiing and in-line skating in biathletes. Medicine and Science in Sports and Exercise: 595-560.
Bouchard C, Taylor AW, Simoneau J and Dulac S (1991): In MacDougall JD and Wenger HA and Green HJ (2^nd ed.) Physiological Testing of the High-Performance Athlete. Champaign: Human Kinetics Books, pp. 175-222.
Doyle (1998): Australian Speed Committee. URL http://www.ecn.net.au/~kazdoyle/speedskate/right_fastfacts.html (old link) accessed 28 October 1999. Queensland: Roller Sports Australia Inc.
Fedel FJ and Keteyian SJ (1995): Cardiorespiratory response during exercise in competitive in-line skaters. Medicine and Science in Sports and Exercise: 682-687.
Green S (1995): Measurement of anaerobic work capacities in human. Sports Medicine 19:32-42.
Hubley-Kozey CL (1991): Testing flexibility. In MacDougall JD and Wenger HA and Green HJ (2^nd ed.) Physiological Testing of the High-Performance Athlete. Champaign: Human Kinetics Books, pp. 309-360.
MacDougall JD and Wenger HA (!991): The purpose of physiological testing. In MacDougall JD and Wenger HA and Green HJ (2^nd ed.) Physiological Testing of the High-Performance Athlete. Champaign: Human Kinetics Books, pp. 1-6.
Magee DJ (1997): Orthopedic Physical Assessment. (3^rd ed.) Philadelphia: W.B. Saunders Company.
Melanson E, Freedson PS, Webb R, Jungbluth S and Kozlowski N (1996): Exercise responses to running and in-line skating at self-selected paces. Medicine and Science in Sports and Exercise: 247-250.
Norkin CC and White DJ (1995): Measurement of Joint Motion. A guide to Goniometry. (2^nd ed.) Philadelphia: F.A. Davis Company, pp. 128-131.
Rundell KW (1996): Compromised oxygen uptake in speed skaters during treadmill in-line skating. Medicine and Science in Sports and Exercise: 120-127.
Rundell KW and Pripstein LP (1995): Physiological response of speed skaters to treadmill low walking and cycle ergometry. International Journal of Sports Medicine 16: 304-308.
Schieber RA and Branche-Dorsey CM (1995): In-line skating injuries. Sports Medicine 19:427-432.
Serresse O, Simoneau JA, Bouchard C and Boulay MR (1991): Aerobic and anaerobic energy contribution during maximal work output in 90s determined with vigorous ergocycle workloads. International journal of Sports Medicine 12: 543-547.
Snyder AC, O'Hagan PO, Clifford PS, Hoffman MD and Foster C (1993): Exercise responses to in-line skating: Comparisons to running and cycling. International Journal of Sports Medicine 14: 38-42.
Thoden (1991): Testing aerobic power. In MacDougall JD and Wenger HA and Green HJ (2^nd ed.) Physiological Testing of the High-Performance Athlete. Champaign: Human Kinetics Books, pp. 107-174.
Wallick ME, Porcari JP, Wallick SB, Berg KM, Brice GA and Arimond GR (1995): Physiological responses to in-line skating compared to treadmill running. Medicine and Science in Sports and Exercise: 242-248.