Power, the product of force and velocity, describes the capability of the neuromuscular system to perform work with respect to time. Power is regarded as a critical performance variable in activities such as sprinting (14) and vertical jumping (13,16) and has been suggested to be of greater importance than force production alone (5,11). Although power can be defined simply, the concept of anaerobic power is in reality a multidimensional trait that can be difficult to measure (10). There are many testing methods to assess development and expression of muscular power (5,10). Anaerobic power testing methodologies are often correlated but rarely agree completely, thereby making comparisons between various testing methods difficult (4). For these reasons, specificity and prior athletic experience may be critical when selecting an anaerobic power test for an athlete or team (10).
The Wingate anaerobic test (WAnT) is widely used among sport and exercise scientists as a means of assessing an individual's anaerobic capacity. Previous research has clearly established the reliability and validity of this test (3). Briefly, the WAnT uses a cycle ergometer capable of determining mean power (MP), peak power (PP), and percent fatigue during a 30 seconds maximal effort bout. Concurrent validity has been established in a variety of time-dependent tasks such as sprinting, swimming, and cycling with moderate (r = 0.66) to high (r = 0.86) correlations (3,12).
Though the WAnT is widely used amongst sport and exercise scientists, it has been criticized for its lack of specificity to many common sports skills. The WAnT also requires costly equipment and a great deal of time making it difficult to use in team testing. Because of these drawbacks, many professionals routinely use sprinting, vertical jump, or stair climb tests as measures of anaerobic power instead of the WAnT (16). Others have created sport-specific anaerobic power tests such as for basketball (6) or water polo (2). However, because much time in a strength and conditioning program is spent in the weight room, it would be useful to have an anaerobic power measure that was discontinuous and resistance exercise based. Such a test could be performed in the weight room with little extra equipment.
Previous studies have shown that isokinetic squat measurements (1), squat power (17), and leg press power (15) are significant predictors of vertical jump power. Similarly, the Kansas squat test (KST) was developed to use a resistance-training activity to determine lower-body power. The KST consists of 15 parallel barbell squats performed at a rate of 1 repetition per 6 seconds. With the use of a Fitrodyne computer-interfaced dynamometer, the peak test power, mean test power, and relative fatigue can be determined, analogous to the WAnT. The purpose of this study was to determine the test-retest reliability of the KST and to determine how it compares to a commonly used test of anaerobic power, the WAnT.
Experimental Approach to the Problem
This study tested the reliability of the KST and compared it with the WAnT as a criterion measure. Reliability of the KST was established using a test-retest design. To compare the KST and the WAnT, an experimental crossover design was used where all subjects performed lower-body power testing using both assessments.
Fourteen resistance-trained men (mean ± SD; age = 24.2 ± 3.6 years; weight = 85.8 ± 17.0 kg; height = 175.5 ± 5.4 cm; body fat = 10.8 ± 2.7%) volunteered to participate in this study. Each of the men was currently training and experienced with resistance exercise (4.2 ± 2.7 years training) and was capable of performing a parallel back squat (1 repetition maximum [1RM] = 149.1 ± 38.7 kg). After an explanation of all procedures, subjects completed a weight training and health history questionnaire to verify their eligibility. All subjects completed an informed consent document as approved by the Committee for the Use of Human Subjects and were considered healthy as indicated by a health history questionnaire.
Baseline Measurements and Familiarization
Subjects were required to report to the Human Performance Laboratory for a total of 7 separate visits. During their initial laboratory visit, at least 1 week before their first test, their height, weight, and percent body fat (as determined through skinfold thickness) were measured and recorded. After these assessments, subjects performed a 1RM test for the back squat on an instrumented Smith machine using methods previously described by Kraemer et al. (9). A Smith machine squat was chosen for this investigation because it allowed the researchers to control the gross motor pattern for the exercise. It also allowed subjects to exert maximal force without concern for balance, as might be the case for the free bar squat during the fatiguing experimental task. After determination of the 1RM, subjects were familiarized with both anaerobic performance tests as described below (i.e., KST and WAnT). On separate occasions, subjects reported back to the laboratory to perform a second familiarization trial for both tests. Therefore, each subject had 2 familiarization trials before each test. This was performed to minimize potential learning effects with either test. Subjects reported to the laboratory 3–5 days after familiarization to perform the WAnT, which was performed first to avoid potential muscle soreness from the KST which could have impaired subjects’ performance on later tests. Three days after the WAnT, subjects returned to the laboratory to perform the first KST. Both the WAnT and the KST were repeated again after 8 weeks.
Wingate Anaerobic Test Cycle Testing Procedures
Before the WAnT, subjects lightly pedaled on a stationary cycle interspersed with two 5-second sprints as a warm-up. A standard 30-second WAnT sprint cycle test was then performed on a specially modified Monark cycle ergometer (Monark Exercise AB, Vansbro, Sweden). During the WAnT, subjects maximally pedaled against a load equal to 0.07 kg·kg−1·BW−1. Peak power, MP, and relative (%) fatigue were determined as previously described (3).
Kansas Squat Test Procedures
Before the squat test, subjects performed a warm-up with free weight barbell squats for 3 sets of 5 repetitions (1 × 5 at 30% 1RM, 2 × 5 at 50% 1RM). The KST was performed in a Smith machine at a load equivalent to 70% of their predetermined system mass achieved during the 1RM testing. System mass at 1RM was found by summing the load of the bar during the 1RM and the individuals' body mass (1RM + body mass). Subjects were instructed to lower the bar to a preset mechanical stop to ensure a parallel squat depth (i.e., posterior thigh parallel with ground) during each repetition. Setting range-of-motion stops in this manner also assured consistency between testing sessions. Foot placement was also recorded during determination of the 1RM for replication in subsequent testing sessions through the use of a foot placement grid. The KST consisted of 15 speed squat repetitions using a computerized metronome to signal initiation of each repetition at 6-second intervals. Each repetition consisted of lowering the weight in a volitionally controlled manner to the bottom of the squat range of motion (where stops were located), a momentary pause in the bottom position, and then maximally accelerating through the concentric phase of the movement upon a verbal cue. Each repetition was completed when the subjects returned to a standing position. Subjects were not permitted to jump off the ground or raise their heels off the ground.
Kinetic variables obtained during the squat test were acquired using a computer-interfaced dynamometer (Fitrodyne; Fritronic, Bratislava, Slovakia). The Fitrodyne device contains a spooled nylon thread tethered to the barbell to determine resulting linear velocity through a velocity transducer. Velocity data were sampled at 100 Hz and linearly smoothed over 50-ms intervals. Force was calculated by taking the first derivative of velocity with respect to time (acceleration), adding the acceleration because of gravity, and multiplying by the system mass (barbell load + body mass). Power was calculated based on measured velocity and calculated force. Using inverse dynamics in combination with the system mass, MP was determined for each repetition (i.e., single repetition power). In addition, the average power for the combined 15 repetitions was calculated and reported as MP for the entire test (i.e., mean test power). Percent (%) fatigue was determined from the % decrease in single repetition power from the repetition with the highest power (i.e., maximum single repetition power) to the last repetition. Maximum single repetition power always occurred during 1 of the first 3 repetitions. Table 1 defines the dependent variables to be measured from both the KST and the WAnT. The Fitrodyne has been previously shown to be reliable (r = 0.97) for assessing human exercise (8) as well as when measuring falling inanimate objects (CV = 0.8–1.3%; unpublished data, A.C. Fry, Ph.D. 2004). Because of the concern over the internal calculations for PP using the Fitrodyne (18), the data were collected using only the MP setting on the Fitrodyne. Pilot work from our laboratory has verified that the MP reported using the Fitrodyne for speed squats, such as used in this study, is not significantly different from MP values derived from a force plate and a linear velocity transducer (unpublished data, A.C. Fry, Ph.D. 2012).
Blood Lactate Analysis
In addition to the kinetic data collected, blood lactate was measured to compare the physiological response of the anaerobic energy system between the WAnT and the KST. Blood samples were taken before and 5 minutes after each test and analyzed using a YSI Lactate analyzer (YSI, Yellow Springs, OH, USA).
All data are reported as X ± SD. Dependent t-tests compared the mean test power and relative fatigue between the first and second trials of the KST. A 2 × 15 repeated-measures analysis of variance (ANOVA) was used to examine the single repetition powers on a repetition by repetition basis between KST trials as well. The intraclass correlation coefficients (ICC) were also calculated between KST trials for single repetition power, mean test power, and percent fatigue. Significance level for each of these tests was set at p ≤ 0.05. Pearson correlation coefficients and t-tests for maximum test power, mean test power, and percent fatigue were performed between the WAnT and the KST. In addition, separate t-tests assessed differences in post exercise HLa and total test work performed between the KST and the WAnT. Because of the multiple comparisons, α levels for all t-tests were adjusted using the Holm-Bonferroni method (7).
To test the reliability of the KST, mean test power and relative fatigue were compared between the 2 KST sessions. There was no significant difference between mean test power (Figure 1) and relative fatigue (Figure 2) for these 2 KST sessions (p > 0.05). In addition, a 2 × 15 repeated-measures ANOVA comparing single repetition power on a repetition by repetition basis found no significant differences (p > 0.05) between the 2 testing sessions (Figure 3). Intraclass correlations between the first and second KST were highly significant for mean test power (ICC = 0.937, p < 0.001; Figure 4) and relative fatigue (ICC = 0.754, p = 0.0084; Figure 5). When comparing all repetitions across all subjects for the 2 KST measures, the single repetition power was also significantly correlated (n = 210; ICC = 0.811, p < 0.0001; Figure 6).
To address the question of whether the KST results are related to other methods of assessing anaerobic power, comparisons were made with the WAnT (Table 2). Significant Pearson correlation coefficients between the WAnT and the KST were found for maximum test power (r = 0.775, p ≤ 0.05) and mean test power (r = 0.752, p ≤ 0.05) but not for relative fatigue (r = 0.174, p > 0.05). Although lactate was greater for the WAnT (p ≤ 0.05), estimated total work was similar for both the KST and the WAnT (p > 0.05).
The KST appears to be a reliable measure of anaerobic power in recreationally resistance-trained males. A useful feature of this test is that it can measure both the MP for each single repetition and the decrease in power produced throughout the test, or a relative fatigue index. This study found maximum test power (i.e., highest single repetition power), mean test power (i.e., mean of the 15 single repetition powers), relative fatigue (i.e., the percent difference between the highest single repetition power and the last single repetition power) to be reliable across testing sessions within the population being studied. Because the KST uses a speed squat, it is important to note that familiarity with the speed squat is likely essential for the reliability of the test.
The KST is an intermittent lifting-specific test of anaerobic power and endurance. Another highly reliable and valid test of lower-body power is the WAnT, which is often used to test these variables. It was important, therefore, for the KST to be compared with the WAnT. Correlations between the WAnT and the KST demonstrated a strong correlation between the 2 tests for maximum test power (r = 0.775). This correlation value is slightly higher than correlations reported between the WAnT and isokinetic endurance tests, 50-m sprint tests, and the Margaria stair climb test (11). The maximum test power observed during the KST was also much more highly correlated with WAnT PP than leg press power (r 2 = 0.775 vs. r 2 = 0.299) (14). As such, the KST was found to be an acceptable measure of anaerobic power.
The correlation between the relative fatigue of the WAnT and the KST was very low (r = 0.174, p > 0.05). These data indicate that the relative fatigue measures of these 2 tests are measuring different variables. Although the WAnT has been shown to be closely linked to the lactic acid production of fast glycolysis (3), the significantly lower lactate levels after the KST indicate that the KST places a different metabolic demand upon the exerciser than the WAnT. Despite having similar work outputs, the KST lasted 90 seconds compared with the 30 seconds duration of the WAnT. Thus, the total session power was lower for the KST. Another possible explanation for disparity in lactate levels is that the KST relied more heavily upon the phosphagen system for energy than the WAnT. The combination of similar work performed and longer duration of the task (i.e., 90 vs. 30 seconds) resulted in less dependence on glycolytic metabolism for the KST compared with the WAnT. Together these factors may account for not only the difference in lactate but also the differences in the relative fatigue between the WAnT and the KST. It is also possible that the difference in modes of contraction (i.e., KST—concentric and eccentric; WAnT—concentric only) may have contributed to some of the apparent metabolic differences.
When developing the KST, 1 option was to stipulate a finite period of time to complete as many speed squats as possible, rather than to initiate each repetition every 6 seconds as was performed in this study. The potential problem with squatting quickly became apparent during pilot testing for this protocol. Rapidly performing squats meant the eccentric phase was more difficult to control, resulting in extreme variability on squat depth. In addition, the total work performed dramatically varied between individuals and between test administrations. By initiating each repetition every 6 seconds, the total time for the entire test is reasonably constant (approximately 90 seconds), the descending portion of each repetition could be performed in a controlled manner, and proper squat depth could be properly regulated. A contributing factor to the duration of the KST was the load used. Subsequent to pilot testing, a load of 70% of system mass (i.e., 70% body weight + 1RM squat) was found to permit successful completion of the required 15 repetitions, while also resulting in appropriate levels of fatigue. An additional consideration was which resistance exercise to use for a test designed to examine lower-body power and power-endurance. Commonly performed high power exercises such as the clean or snatch can certainly provide high power production, but exercise technique can easily deteriorate when performing high numbers of repetitions. Other lower-body tests involving power endurance, such as the Bosco anaerobic test, have simply used body weight while performing repeated vertical jumps (13). Although repeated vertical jumps are certainly easy to perform and result in a valid assessment of lower-body power and power endurance, they present several problems when using them for assessment purposes. One is that a force plate is required, thus requiring a well-equipped laboratory or a uniquely equipped strength and conditioning facility. Another issue is that repeated vertical jump tests use only body weight as a resistance. In many sport settings, power production when working against an external load is desirable, such as with the KST. The net result is that the KST appears to be a useful and practical assessment tool for many field settings.
Although this study has demonstrated that the KST is both reliable and useful, its correlative value with many types of anaerobic exercise and sport has not been clearly demonstrated, as is also the case for the WAnT. In addition, the KST has no normative values for group comparison; nor is there currently any data concerning use of the KST for women. Because of these shortcomings, further research on the KST should be undertaken to answer these questions.
The data presented here indicate that the KST is a reliable and useful measure of anaerobic power in recreationally resistance-trained men. Whether this test can be appropriately used for individuals with greater or less resistance-exercise experience remains to be studied. One advantage of the KST over the WAnT is its specificity to resistance training. The intermittent work of the KST likely allows a better assessment of the phosphagen system than the WAnT, which is heavily reliant upon the HLa system (1). The KST might also be useful as a reliable measure of lifting-specific anaerobic endurance that could be used as an alternative measure for monitoring training progress in a weight room setting. By measuring the single repetition power, mean test power, and a measure of power fatigue, the KST can provide the coach with a great deal of performance information. Thus, the lifting-specific KST could prove to be a useful tool for strength and conditioning professionals.
1. Ashley CD, Weiss LW. Vertical jump performance and selected physiological characteristics of women. J Strength Cond Res 8: 5–11, 1994.
2. Bampouras TM, Marrin K. Comparison of two anaerobic water polo-specific tests with the Wingate test. J Strength Cond Res 23: 336–340, 2009.
3. Bar-Or O. The Wingate anaerobic test: An update on methodology, reliability and validity. Sports Med 4: 381–394, 1987.
4. Cronin J, Sleivert G. Challenges in understanding the influences of maximal power training on improving athletic performance. Sports Med 35: 213–234, 2005.
5. Harman EA. The measurement of human mechanical power. In: Physiological Assessment
of Human Fitness. Maud P., Foster C., eds. Champaign, IL: Human Kinetics, 2006.
6. Hoffman J, Epstein S, Einbinder M, Weinstein Y. A comparison between the Wingate anaerobic power test to both vertical jump and line drill tests in basketball players. J Strength Cond Res 14: 261–264, 2000.
7. Holm S. A simple sequentially rejective multiple test procedure. Scand J Stat 6: 65–70, 1979.
8. Jennings CL, Viljoen W, Durandt J, Lambert M. The reliability of the Fitrodyne as a measure of muscle power. J Strength Cond Res 19: 859–863, 2005.
9. Kraemer WJ, Ratamess NA, Fry AC, French DN. Strength training: Development and evaluation of methodology. In: Physiological Assessment
of Human Fitness. Maud P., Foster C., eds. Champaign, IL: Human Kinetics, 2006. pp. 119–150.
10. Maud P, Berning JM, Foster C, Cotter HM, Dodge C, DeKoning JJ, Hettinga FJ, Lampen J. Testing for anaerobic ability. In: Physiological Assessment
of Human Fitness. Maud P., Foster C.. eds. Champaign, IL: Human Kinetics, 2006.
11. Newton RU, Kraemer WJ. Developing explosive muscular power: Implications for mixed methods training strategy. Strength Cond J 16: 20–31, 1994.
12. Patton JF, Duggan A. An evaluation of tests of anaerobic power. Aviat Space Envir Med 58: 237–242, 1987.
13. Sands WA, McNeal JR, Ochi MT, Urbanek TL, Jemni M, Stone MH. Comparison of the Wingate and Bosco anaerobic tests. J Strength Cond Res 18: 810–815, 2004.
14. Sleivert G, Taingahue M. The relationship between maximal jump-squat power and sprint acceleration in athletes. Eur J Appl Phys 91: 46–52, 2004.
15. Thomas M, Fiatarone MA, Fielding RA. Leg power in young women: Relationship to body composition, strength, and function. Med Sci Sports Exerc 28: 1321–1326, 1996.
16. Vandewalle H, Peres G, Monod H. Standard anaerobic exercise tests. Sports Med 4: 268–289, 1987.
17. Weiss LW, Relyea GE, Ashley CD, Propst RC. Using velocity-spectrum squats and body composition to predict standing vertical jump ability. J Strength Cond Res 11: 14–20, 1997.
18. Willardson JM. Incorrect variables reported. J Strength Cond Res 24: 1–2, 2010.