Research Quarterly for Exercise and Sport
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Relationship Between Functional Classification Levels and Anaerobic Performance of Wheelchair Basketball Athletes Bartosz Molik , James J. Laskin , Andrzej Kosmol , Kestas Skucas & Urszula Bida To cite this article: Bartosz Molik , James J. Laskin , Andrzej Kosmol , Kestas Skucas & Urszula Bida (2010) Relationship Between Functional Classification Levels and Anaerobic Performance of Wheelchair Basketball Athletes, Research Quarterly for Exercise and Sport, 81:1, 69-73, DOI: 10.1080/02701367.2010.10599629 To link to this article: http://dx.doi.org/10.1080/02701367.2010.10599629
Published online: 23 Jan 2013.
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Date: 12 January 2016, At: 11:51
Molik, Laskin, Kosmol, Skucas,Physiology and Bida Research Quarterly for Exercise and Sport ©2010 by the American Alliance for Health, Physical Education, Recreation and Dance Vol. 81, No. 1, pp. 69–73
Relationship Between Functional Classification Levels and Anaerobic Performance of Wheelchair Basketball Athletes
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Bartosz Molik, James J. Laskin, Andrzej Kosmol, Kestas Skucas, and Urszula Bida
Wheelchair basketball athletes are classified using the International Wheelchair Basketball Federation (IWBF) functional classification system. The purpose of this study was to evaluate the relationship between upper extremity anaerobic performance (AnP) and all functional classification levels in wheelchair basketball. Ninety-seven male athletes from the Polish and Lithuanian national wheelchair basketball leagues took part in this study. The Wingate Anaerobic Test was used to assess four AnP indexes with an arm crank ergometer. The level of AnP in wheelchair basketball athletes depends to some degree on classification level. No significant differences were found for the AnP indexes across levels 1.0–2.5 and 3.0–4.5. However, the AnP level for those in classes 1.0–2.5 was significantly lower than those in classes 3.0–4.5. The findings from this study provided some evidence that the IWBF functional classification system should be reexamined and that a consolidation of the current eight levels might be in order.
Key words: arm crank ergometer, Wingate test
F
or a sport classification system to be valid and acceptable, the outcome of an event must depend on functional abilities, such as balance, coordination, natural talent, training, skill, physical fitness, and motivation, rather than disability-centered variables, such as spasticity, level of amputation, or level of paralysis (Strohkendl, 2001; Vanlandewijck & Chappel, 1996). In 1982, Strohkendl introduced a functional classification system that was adopted by the International Wheelchair Basketball Federation (IWBF, 1982). Wheelchair basketball athletes were divided into five main classes: 1.0, 2.0, 3.0, 4.0, and 4.5 (4.5 being the greatest level of functional ability) and three subclasses 1.5, 2.5, and 3.5, used for athletes with mixed characteristics (Courbariaux, 1996; IWBF, 2004). With this functional system, the limit is 14 points (based on classification level) for the five players on the floor at any one time. Submitted: June 19, 2007 Accepted: October 29, 2008 Bartosz Molik, Andrzej Kosmol, and Urszula Bida are with the Department of Sport for Persons with Disabilities at The Jozef Pilsudski University of Physical Education. James J. Laskin is with the School of Physical Therapy and Rehabilitation Sciences at The University of Montana–Missoula. Kestas Skucas is with the Department of Adapted Physical Activity at the Lithuanian Academy of Physical Education.
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Wheelchair basketball combines repeated short, intense exercise bouts that include rapid acceleration and deceleration, dynamic positions changes, and maintaining or obtaining one’s position on the court (Coutts, 1992). The ability to successfully perform these efforts depends on the athlete’s fitness as measured by anaerobic power (AnP). The IWBF (2004) classification system differentiates between functional levels such that each classification is mutually exclusive across performance domains. Meeting this core premise has been the subject of much discussion, research, and debate among coaches, athletes, officials, and researchers (Molik & Kosmol, 2001). Hutzler’s (1998) review suggested that a functional classification level can predict an athlete’s AnP, similar to what was reported with aerobic performance. A number of studies have used AnP to compare wheelchair basketball athletes across the range of functional levels. Hutzler (1993) demonstrated relatively high correlations between players’ classification and their mean anaerobic capacity (r = .717, p = .015). Hutzler and Sagiv’s (1996) analysis of 57 wheelchair basketball players demonstrated the similarity in power output between those with low lesion level paraplegia (below the sixth thoracic vertebra [T6] complete) and those with polio. They suggested athletes could be categorized into three groups versus the eight used by the IWBF: Group I (paraplegia above T6 complete), Group II (paraplegia complete below T6 or equivalent and polio), and Group III (lower limb amputations). Vanlandewijck, Goris, and Verstuyft (1996) demonstrated that wheelchair
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basketball athletes’ on-court performance (a series of 20-m sprints and an incremental velocity shuttle-run to exhaustion test) depended on AnP rather than aerobic capacity. Hutzler, Ochana, Bolotin, and Kalina (1998) examined 50 athletes from different sport disciplines (22 of whom played wheelchair basketball). Those who did not play wheelchair basketball were classified using the IWBF system. Significant differences were found between those classified as Level 1.0 (complete paraplegia) and 4.0 through 4.5 (polio or amputation with one leg affected). Those in Levels 2.0–3.5 (low-level paraplegia or both legs affected by polio) had AnP values significantly different from those in Class 1.0 as well as Classes 4.0 through 4.5. Interestingly, significant intergroup differences were obtained only for peak anaerobic power not for aerobic capacity. Molik, Kosmol, and Rutkowska (2005) evaluated 28 wheelchair basketball athletes divided into four groups (excluding half-point players). They observed no significant differences in AnP between Classes 1.0–2.0, 2.0–3.0, and 3.0–4.0. Although not consistent, it appears from these studies that similarities in AnP exist among some functional classification levels. Further study is warranted to differentiate these similarities among all eight levels. Thus, the purpose of our study was to evaluate the relationship between upper extremities’ AnP and all functional classification levels in wheelchair basketball.
Method The Senate Commission of Science Research Ethics at Jozef Pilsudski University of Physical Education approved this study. Ninety-seven male wheelchair basketball athletes with locomotor disabilities participating in the Polish and Lithuanian national wheelchair basketball leagues took part in this study. All athletes were previously classified according to the IWBF system. All were at least 17 years of age, had at least 1 year of wheelchair
basketball experience, were actively training and played regularly during league games. The athletes were divided into eight groups based in their IWBF classification level. The athletes’ characteristics are provided in Table 1. The Wingate Anaerobic Software Package (Wingate v. 1.07b; Lode B. V., Groningen, The Netherlands) was used to perform the Wingate Anaerobic Power Test (WanT) on a manual arm crank ergometer (ACE). To maximize trunk stability, the athletes used their own basketball wheelchair and strapping system as appropriate. The ACE was firmly affixed to a wall-mounted gymnastic ladder. The ergometer’s rotation axis was set so that it was level with the athlete’s glenohumeral joints. Two assistants stabilized the athlete’s wheelchair to help minimize rotational movements during arm cranking. Each athlete performed one WanT protocol, which consisted of a 2-min warm-up and cranking at 60 rpm, with 50 W resistance. Once the warm-up was completed, the resistance automatically set at the predetermined testing level, and the athlete was instructed to crank as fast as possible for 30 s. The software began the 30-s countdown as soon as 25 rpm was reached. Athletes received verbal encouragement throughout the test. When assessing AnP, the ergometer’s resistance is typically based on the individual’s total body mass. We modified this calculation to account for trunk stability and functional upper extremity muscle mass. The IWBF classification system identifies those without and with active pelvic stability as Categories A and B, respectively (Courbariaux, 1996; IWBF, 2004). Category A represents athletes classified as Levels 1.0 through 2.5, and category B corresponds to Levels 3.0 through 4.5. Resistance for those in Category A was set at 3.5% of their body mass and 4.5% of body mass for those in Category B. We measured four indicators during the WanT: (a) peak power output (PP; the highest 5-s power output), (b) mean power output (MP; the average power sustained throughout the 30-s period), (c) time to achieve peak
Table 1. Demographic data of the athletes representing the eight wheelchair basketball functional classification levels Levela
n
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Total
16 7 12 6 15 9 17 15 97
Age (years) M SD 27.9 34.1 27.6 26.0 32.0 31.8 27.8 27.3 29.0
9.0 9.6 8.4 6.3 8.2 7.9 7.8 6.6 8.1
Body mass (kg) M SD 70.6 67.3 75.0 74.0 70.0 80.0 71.0 76.0 73.0
11.9 10.8 14.0 14.4 13.2 17.9 12.0 12.0 13.1
Height (cm) M SD 177.0 173.0 177.0 170.0 180.0 180.0 179.0 179.0 178.0
9.1 8.9 8.9 6.4 6.4 8.5 6.3 6.9 7.9
Experience (years) M SD 4.9 11.0 5.6 4.7 9.2 7.3 8.6 5.1 6.9
3.0 10 4.3 3.3 6.7 3.5 6.9 3.2 5.5
Note. M = mean: SD = standard deviation. a International Wheelchair Basketball Federation classification levels.
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power (TPP; the number of seconds required to achieve peak power), and (d) fatigue index (FI; the drop in power from peak power to the lowest power). The data was analyzed using STATISTICA 5.1 (StatSoft, Inc., Cracow, Poland). A one-way analysis of variance (ANOVA) was used to compare groups for each AnP parameter. Newman-Keul’s analysis was used for post hoc comparisons. In addition, to further validate any significant post hoc comparisons Mann-Whitney U tests were used. An alpha level of p ≤ .05 was used as the criterion for statistical significance.
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Results In general, the functional levels of athletes with active pelvic control (Category B) and, therefore, the least functional limitations demonstrated the greatest PP (542 ± 115 W, Level 4.5) and MP (398 ± 70 W, Level 3.5). While the observed absolute values for PP and MP were the lowest for Category A athletes (no active pelvic control), these individuals demonstrated the greatest fatigue-resistant performances as measured by the FI (see Table 2). The one-way ANOVA demonstrated significant main effects (p ≤ .001) in all AnP parameters: MP, F(7, 89) = 14.09, p < .05; PP, F(7, 89) = 12.85, p < .05; FI, F(7, 89) = 7.22, p < .05); except TPP, F(7, 89) = .60, p > .05. Post hoc comparisons revealed no significant differences between Classes 1.0 through 2.5 and Classes 3.0 though 4.5. Significant differences were found between Levels 1.0 and 1.5 compared to Levels 3.0 through 4.5. There were also significant differences between Levels 2.0 and 2.5, compared to Levels 3.5 through 4.5. There was also a statistical difference in MP between Levels 2.0 and 3.0 as well as between Levels 2.5 and 3.0 for PP (see Table 3).
Table 2. Indexes of anaerobic performance across the eight wheelchair basketball functional classification levels Levela 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
n 16 7 12 6 15 9 17 15
MP (W) M SD 223 268 287 280 344 398 389 382
55 28 58 29 51 70 77 80
M
PP (W) SD
306 339 390 371 472 532 539 542
76 40 101 44 77 104 123 115
FI (W/s) M SD 6.8 6.5 8.1 7.6 10.8 11.5 12.6 13.7
.0 2 1.9 3.2 1.0 3.1 2.9 3.9 3.8
Note. MP = mean power; PP = peak power; FI = fatigue index; M = mean: SD = standard deviation. a International Wheelchair Basketball Federation classification levels.
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Discussion Vanlandewijck, Spaepen, and Lysens (1995) suggested that AnP should be considered a determining classification factor in wheelchair sport. However, due to a small sample size and methodology these authors and others did not assess AnP across all eight classification levels, but rather only the four basic levels (Hutzler, 1993; Hutzler et al., 1998; Hutzler & Sagiv, 1996; Molik et al., 2005; Vanlandewijck et al., 1995). By evaluating upper extremity AnP across all eight IWBF functional classification levels, this study’s findings complement that prior work. Those studies demonstrated that in terms of AnP the similarities in performance between various functional classification levels are not mutually exclusive. The current study found that the AnP parameters, such as MP, PP, and FI, were not significantly different for Classes 1.0 though 2.5 and Classes 3.0 through 4.5. Prior investigations by Vanlandewijck et al. (1996) and others suggested it was possible to establish three functional classification groups based on AnP, with Level 1.0 remaining a unique group. Our investigation did not support this conclusion; in fact, we demonstrated there was no significant difference in the performance of classification Levels 1.0 through 2.5. This may be due to the
Table 3. Newman-Keul’s post hoc comparisons (p values) between relevant wheelchair basketball functional classification levels Level a 1.0 vs. 1.5 1.0 vs. 2.0 1.0 vs. 2.5 1.5 vs. 2.0 1.5 vs. 2.5 2.0 vs. 2.5 2.0 vs. 3.0 2.0 vs. 3.5 2.0 vs. 4.0 2.0 vs. 4.5 2.5 vs. 3.0 2.5 vs. 3.5 2.5 vs. 4.0 2.5 vs. 4.5 3.0 vs. 3.5 3.0 vs. 4.0 3.0 vs. 4.5 3.5 vs. 4.0 4.0 vs. 4.5
MP (W)
PP (W)
FI (W/s)
.1 .1 .1 .78 .66 .81 .041 .001 .002 .002 .059 .0007 .001 .002 .2 .22 .16 .74 .8
.44 .19 .27 .44 .44 .66 .053 .003 .003 .004 .047 .001 .001 .001 .16 .25 .34 .86 .94
.84 .61 .54 .66 .69 .75 .044* .033 .007 .0008 .052 .026 .004 .0004 .62 .41 .16 .44 .41
Note. MP = mean power; PP = peak power; FI = fatigue index. a International Wheelchair Basketball Federation classification. *p > .05; difference not confirmed by Mann Whitney U analysis.
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“liberalization” of classification procedures and the sport’s growth in popularity. When many of the other studies were conducted, Level 1.0 represented athletes with paraplegia no lower than T6, compared to the current standards. Those with lesion levels of T8 and some individuals with polio and spina bifida were previously classified as 1.5 or 2.0 but are now considered to be Level 1.0 (Courbariaux 1996). In addition, we wanted to ensure the athletes’ maximal performance. Trunk stability was maximized using the individuals’ basketball chair and strapping. Also, because these subclasses (1.5, 2.5, and 3.5) are considered special cases and not commonly used, our sample sizes were quite small; therefore, potential differences between Levels 1.0 and 1.5 in particular may have been missed. These alterations in the classification process and our methodology may limit the comparability of our results with prior work. For example, Hutzler et al. (1998) reported no significant differences between functional Levels 2.0 through 3.5, whereas the present study clearly demonstrated significant differences between classification Levels 2.0–3.0, 2.0–3.5, and 2.5–3.5 (see Table 3). In absolute terms, our results mirror the pattern found in most studies in which those with the highest functional levels demonstrate the highest performance level (Hutzler, 1998; Hutzler & Sagiv, 1996; Molik et al., 2005). For instance, the MP reported by Hutzler (1993) for classification Levels 1.0 and 4.0 was 305 W and 408 W, respectively. In the current study, the mean power of Cass 1.0 and 4.0 athletes was 333 W and 481 W, respectively. Similar differences are noted in the PP values between both studies. Another difference between previous AnP studies on this population and the present study is the calculation used to determine WanT resistance. Hutzler (1993) set resistance at 2.5% of the athletes’ body mass. Hutzler et al. (1998) reported that in his previous work the resistances were too low, so they increased resistance to 3.5%. Using this resistance level, the average MP and PP for athletes’ in functional Level 1.0 was similar to what we found (MP 226 W and PP 337 W as compared to MP 223 W and PP 306 W). However, for those in classification Level 4.5 there was a large difference in the MP reported (MP 456 W and MP 382 W, respectively). The lower MP found in the current study may be directly related to the fact that our athletes were using 4.5% versus 3.5% of their body mass as the resistance level, thus, resulting in the observed depressed cranking rate, lowered MP, and higher PP. The variable crank rates observed in earlier studies (Hutzler, 1993; Hutzler et al., 1998; Hutzler & Sagiv, 1996) helped Jacobs, Mahoney, and Johnson (2003) justify the 3.5% body mass resistance for athletes with paraplegia. In preliminary work, we used a consistent relative resistance load of 3.5%, like Hutzler et al. (1998). We found the crank rate in levels greater than 3.0 (Category B) to be significantly higher (perception of ease, minimized FI, and lower PP) than those at lower functional classes (Category
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A). Those in Category A again used resistances set at 3.5%; however, those in Category B used resistances set at 4.5%. When crank rate was evaluated using this differential resistance, no significant differences were found across the various classes. We contend that if individuals can achieve similar crank rates, then one more confounding variable has been removed and a more objective comparison of athletes across all eight classes is possible. Since Hutzler’s (1993) initial attempt to evaluate AnP in this population, there has been and will continue to be much discussion about the optimal load for athletes with disabilities completing WanT. In a review article, Hutzler (1998) suggested that resistances should be set between 2–4% of body mass for PP analysis. Bhambhani’s (2002) review article concluded that there is no significant functional difference in the upper extremity AnP between able-bodied individuals and those with low-level paraplegia (lesion at T8 or lower) and that higher resistances should be used. This finding supported our decision to use differential work loads based on functional classification. As sport for people with physical disabilities develops and grows, the sophistication of physiological testing and parameters used will need to be reexamined periodically. One challenge in interpreting AnP testing results in wheelchair users is inconsistent methodologies. The wheelchair ergometer, wheelchair treadmill, and ACE have all been used. Wheelchair ergometry appears to be the most sport specific and functional exercise mode for wheelchair athletes. Hutzler (1998) and Hutzler, Vanlandewijck, and Van Vlierberghe (2000) demonstrated the reliability of WanT, performed on a wheelchair ergometer and based on a comparative analysis with ACE, and recommended wheelchair ergometry for AnP testing. Although wheelchair ergometry may be superior in function, the ergometer is a custom-made device, difficult to calibrate, expensive, and not typically portable, whereas the Lode ACE is widely available, allows for standardized calibration, and is portable. In addition, wheelchair ergometry and treadmill AnP may be confounded by the athletes’ propulsion technique and fit in a standardized “chair.” Therefore, our decision to use an ACE to evaluate AnP was an attempt to not only eliminate as many confounding variables as possible but also to allow future researchers to easily replicate our study within the wheelchair basketball population and/or in trained or untrained athletes representing different sport disciplines or disability types. This study is the first to use a sample size large enough for AnP examination across all eight wheelchair basketball functional classification levels. It shows that upper extremity AnP is not significantly different between all eight levels. A primary tenet of any classification system is that each should be mutually exclusive. Lack of a differential response to this or any other measure of physiological performance alludes to the possibility for modifying the classification system. Based on upper extremity AnP only,
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our data suggest an amalgamation of levels may be warranted. However, AnP is one of many variables (aerobic performance, biomechanical analysis, standardized sportspecific performance, and fitness testing) that should be considered prior to making any changes to the current IWBF classification system (Brasile, 1990). Our suggestion is to retain the current observational philosophy of functional classification but to also consider implementing some form of physiological testing. This combined approach may not only better differentiate functional classification levels in practice but also help in determining the appropriate number of mutually exclusive classes.
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Conclusion The upper extremity AnP performance of wheelchair basketball athletes is related to some degree to their functional classification level. The level of AnP, notably MP, PP, and FI, demonstrated by athletes in classification Levels 1.0–2.5 (Category A) was significantly lower than those in functional Classes 3.0–4.5 (Category B). This study did not support the suggestion that classification Level 1.0 athletes should maintain a unique level. The findings of this study provide some evidence that a reexamination of the IWBF functional classification system is warranted and a consolidation of the current eight levels might be in order. However, any modification of the functional classification system for wheelchair basketball should be based only on objective performance and physiological criteria.
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Authors’ Notes This research was supported by grant No. DS-127 from the Polish Ministry of Higher Education and Science. Please address all correspondence concerning this article to Bartosz Molik, The Jozef Pilsudski University of Physical Education, 00-968 Warszawa, Marymoncka 34, Wydzial Rehabilitacji, Polska. E-mail:
[email protected]
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