Power is the rate at which work is performed (16). It is a highly desirable, if not essential fitness component for many sports. Historically, the majority of methods for assessing power, with the exception of medicine ball tests, have focused on the lower extremity (ie, standing and running long jumps, vertical jumping for height, vertical jumps on force platforms and stair sprinting). Tests for upper extremity power do not seem to be as well represented (19).
The medicine ball put (MBP) has been used for more than thirty years (11) and is still frequently used when assessing upper body power (1,17,19), establishing baseline upper body power for pre/post-training studies (9) and as a criterion measure (21). Smith Machines with improvised timing devices have also been studied (2,4,19); however, a universally recognized “gold standard” test of upper body power has yet to emerge.
A properly administered 1 repetition maximum bench press, although not a test of power, has long been recognized as a “gold standard” test of absolute strength. If the load, grip width, and vertical distance could be controlled with lifting speed free to vary based on the maximum volitional speed of the lifter, this approach might serve as a valid method of testing upper body power. At the very least, a strong case could be made that such a test would have “logical validity” (13) in that the construct of power is clearly visible within the performance (13) and also within the formula used to quantify power (15).
The purpose of this study is to develop and refine the methodology for administering a bench press power (BPP) test, examine it for test retest reliability and, in addition, determine concurrent validity (8,10,11,13) by determining the relationship between BPP scores using formula 1 and the distances attained on the MBP, a frequently administered and accepted test of upper body power (2,5,9,17,18,19,21).
Experimental Approach to the Problem
“A test has face validity or logical validity when it obviously measures the desired skill or ability (13).” The construct to be measured in this study is power, more precisely, a select expression of upper body power as determined by a constant load bench press executed at maximum speed over a set distance. The argument for logical validity is based upon the concept that to successfully execute a bench press, strength is required and; in addition, work is accomplished. If time is factored into the work performance (ie, how quickly the repetition is executed), strength measures can legitimately be transformed to power measures (15) using Formula 1. For this reason, a BPP test, as described, would be considered a logically valid test of upper body power. There is little difference, if any, in concept between a BPP test and the widely accepted Margaria-Kalamen test of lower extremity power in that the same concept is applied and the same formula used. Body mass; however, is the resistive force in the Margaria-Kalamen stair sprinting protocol; whereas, bar mass is the resistive force in the bench-pressing protocol.
“Construct validity evidence is essentially a marriage between logical (content) and statistical validity procedures (14).” Logical validity alone may be considered a weak expression of validity; therefore, concurrent validity (14) will also be determined. “Concurrent validity is the extent to which test scores are associated with those of other accepted tests that measure the same ability (14).” Using a “gold standard” test as the criterion measure is preferable; however, a universally accepted “gold standard” for assessing upper body power has yet to emerge. Considering the frequency with which the MBP has been cited in the literature (1,2,5,9,17,18,19,21) and the precedent for using it as a criterion measure (21), the MBP will serve as the criterion measure. The investigators hypothesize that a direct relationship (ie, r > 0) will exist between BPP scores and MBP distances.
In addition to determining concurrent validity, the power output scores acquired using the proposed BPP test will be compared with power output scores acquired in an earlier research project (20) that used a modified Smith Machine (MSM) equipped with a timing device to measure upper body BPP (n = 8). The MSM study (20) found a strong correlation between the MSM test and the Linea Bench Press, an isokinetic dynamometer produced by Loredan Biomedical, a company that may no longer be in business. To determine if the power outputs were different in these 2 independent samples of college age males, an unpaired t test at an alpha level of 0.05 was used to test the 2-tailed hypothesis (ie, BPP ≠ MSM) as an alternative to the null hypothesis (ie, BPP = MSM). Failing to reject the null would indicate similar power outputs by both samples of college age males; thereby, providing additional support for the validity of the 2 methods of assessing upper body power.
Forty-three university students participated in the study. Participant characteristics are presented in Table 1. The study was approved by the University's Institutional Review Board. As a requirement of the Institutional Review Board, all investigators completed an online training course through the National Institutes of Health training site on the protection of research subjects: http://phrp.nihtraining.com. All participants were informed of the experimental risks, and each subject signed an informed consent document before the investigation.
Bench Press Power Test
Different grip widths result in different curvilinear paths (12); therefore, grip widths were standardized at approximately 130% of biacromial breadth (slightly wider than shoulder width) to reduce interindividual variability with regard to bar path and joint angles during execution of the lift. The grip width was arbitrarily chosen; however, 130% of biacromial breadth is a comfortable grip width for most individuals and has been used in previous bench press studies (3,22). A standard anthropometric measurement device (Figure 1) was used for measuring biacromial breadth for purposes of establishing 6 different possible grip widths (ie, 41 cm [16 in], 45.7 cm [18 in], 50.8 cm [20 in], 55.9 cm [22 in], 61 cm [24 in] and 66 cm [26 in]). An Olympic bar, marked with different color tape to correspond with each of the 6 possible grip widths, was used to facilitate quick recognition and rapid acquisition of grip widths during testing.
To standardize the vertical distance the bar traveled, a device was constructed (Figure 2) to insure the infrared beam, emitted by the Speedtrap II timing system by Brower, (6,23) was at 0.3 meters (12 inches), a distance established arbitrarily but sufficiently short of a lockout on all participants.
Colored tape was also used on the device to identify all possible grip widths. Each lifter, using their predesignated grip width, held the device in contact with the chest while the 0.3 m beam height was adjusted. Adjustments were accomplished using 2 towers, composed of plastic sections manufactured by Reebok. The towers were placed several feet from the head and feet of the lifter (Figure 3) and topped off using ceramic tiles 0.635 cm thick (1/4 in) to support the infrared transmitter and receiver.
When the transmitter was turned on and, as long as the device was held vertically by the lifter (Figure 2), the beam was blocked and there was a continuous audible signal indicating beam impedance. Coarse adjustments of beam height were accomplished by adding or removing plastic sections to raise or lower the 2 towers (Figure 3). As plastic sections elevated the beam closer to clearing the device, finer adjustments were made by adding additional ceramic tiles 0.635 cm thick. If the signal continued, finer adjustments were made using steel discs 0.3175-cm (1/8 in) thick (Figure 4) until the signal disappeared. The number of sections, tiles, and discs necessary to acquire the precise 0.3 m distance for each participant was recorded before test day to facilitate and speed up the testing process.
For the bench press, any stable bench that does not interfere with the lifter's movements is satisfactory. Weight room facilities were not available during scheduled data collection periods, therefore, “The Step,” by Reebok, was used for conducting the BPP test (Figure 3). Plastic sections at each end were used to support “The Step,” to insure that elbows did not make contact with the floor during the BPP test. An Olympic bar was loaded with two 20.4 kg plates for the males and two 2.3 kg plates for the females resulting in total loads of 61.4 kg (135 pounds) and 25 kg (55 pounds), respectively.
Lifters were instructed to lay supine on the bench and the infrared transmitter and receiver were turned on, lined up, and positioned using the precise number of sections, tiles, and washers previously determined to result in the standard 0.3 m beam height. Two spotters, 1 on each side of the lifter, lifted the bar from the floor and handed it to the participant below beam height to avoid prematurely activating the timing system. Spotters supported the weight until the lifter was able to comfortably place the hands on predetermined tape marks corresponding to 130% of the lifter's biacromial breadth. An effort was made to insure a smooth transition in the handoff of the loaded bar from the spotters to the lifter at which time the lifter lowered the bar slowly to the chest. Upon chest contact the signal “UP” was given and at the first sign of upward movement the timing mechanism (Figure 5) was manually activated.
Lifters were instructed to explode upward at maximum volitional speed. When the bar broke the beam path, the time it took for the bar to travel the 0.3 m distance was automatically determined in hundredths of seconds. Figure 6 shows the completed position of the BPP test relative to a simulated infrared beam positioned at the 0.3 meter distance.
Power scores were computed using Formula 1. To minimize the practice effect, testing included 1 practice day and 1 test day with 3 trials. Participants' scores were the average of trials 2 and 3 on test day.
Medicine Ball Put
A 45° incline bench was used for the MBP to facilitate an optimal trajectory of 45° (Figure 7) and to result in arm to torso angles similar to that, which occurred in the BPP test.
The women and men used 6 and 9 kg medicine balls, respectively. All participants were allowed a practice throw and 2 test throws and were allowed ≥2-minute recovery periods between trials. The balls were covered in carbonate of magnesia (ie, gymnastics chalk) before each attempt to facilitate the accurate measurement of distances thrown. A room with a clearance of 8 m was used for conducting the test. A measuring tape was placed on the floor with the near end positioned under the frame of the bench to anchor it. The tip of the tape was oriented so that it would coincide approximately with the posterior portion of the medicine ball as it rested on each participant's chest in the ready position (Figure 8).
The tape extended outward 7.62 m (25 feet), well beyond the capabilities of all participants, and was secured to the floor for increased stability. On each side of the measuring tape, a border was created with duct tape that permitted a region of 0.6 m (2 feet) within which the ball must land to be legal. Any throw that landed outside the region was not counted and had to be repeated after a minimum of 2 minutes of passive recovery. Balls landing within the region were considered legal, and the distances were recorded to the nearest 2.54 cm (1 in). The near edge of the chalk mark (in the direction of the bench) was used for measuring the distance thrown.
A Shapiro-Wilk statistic was conducted at an alpha level of 0.05 to test the hypotheses that data were normally distributed for both the BPP test and the MBP.
Pearson Product Moment Correlation was used to determine the relationship between BPP scores and MBP distances (ie, concurrent validity). An “a priori” decision was made to adopt a 1-tailed hypothesis (ie, r > 0) at an alpha level of 0.05.
Trials 2 and 3 for both the BPP test and the MBP were analyzed for test-retest reliability using model alpha, Intraclass R in conjunction with a two way, mixed analysis of variance at an alpha level of 0.05 (14).
Results of the Shapiro-Wilk indicated that the distribution of scores, for both males and females, on the BPP and the MBP did not differ significantly from normal. Results are presented in Table 2.
The concurrent validity coefficients were determined by correlating the average score of trials 2 and 3 on the BPP test and the average scores of trials 2 and 3 on the MBP test: Males, r = 0.86, p = 0.00; Females, r = 0.79, p = 0.00. The statistical conclusions were to reject the null and accept the alternative hypotheses (ie, r > 0).
The results of the independent t test comparing power scores acquired using the MSM (20) and power scores generated by the BPP test indicated no significant difference in the power output of the 2 independent groups of college age males: t = 0.245, p = 0.809 (Table 3). The statistical decision; therefore, was to reject the alternative hypothesis (BPP ≠ MSM) and conclude that the 2 testing methods yielded similar power outputs (ie, not significantly different) (Table 3).
Results of the Intraclass R indicated excellent test retest reliability for both males and females on both the BPP and the MBP tests. Reliability coefficients are presented in Table 4, and a percentile table for both the BPP and the MBP tests is presented in Table 5.
The substantive conclusion was that the BPP test was a valid test of upper body power when using the MBP as the criterion measure. Scatter plots of the relationships are presented for both males and females in Figures 9 and 10, respectively.
Strength is the ability to exert a maximum force (7); whereas, power is how rapidly a fixed load can be vertically displaced (15). If mass and distance are held constant and time is accurately measured, power can be computed. The BPP test and the method of scoring meet these criteria. There was initial concern that starting the timer manually might deleteriously affect reliability due to the brief time it took for the bar to cover 0.3 m (ie, < 1 sec); thereby, potentially compromising validity. This concern; however, was not realized as demonstrated by the excellent test-retest reliability observed (ie, average R = 0.95 and 0.92 for males and females, respectively). This was accomplished by using the same person to manually activate the timer for all tests and the use of an infrared beam to terminate timing. Consistency was further enhanced by providing a practice session to reduce the potential of a practice effect.
The Speedtrap II, from Brower Timing Systems, is routinely used for testing sprinting speed; however, it may also be used for testing upper body power. It comes with a touch pad that might, as an alternative, be placed on the chest so that as the bar makes contact, the timing mechanism will be armed and subsequently activated as the bar leaves the chest; thereby, eliminating a manual start. This approach would have been employed; however, there was a malfunction of the touch pad that prevented its use. A suggestion for future research would be to incorporate a touchpad into the testing to determine if validity can be further strengthened. In closing, considering the strong concurrent validity, excellent test retest reliability and the presence of strong logical validity, the BPP test may serve as a valid field test of upper body power.
Upper body explosive power is essential for most sports. Football, boxing, powerlifting, gymnastics, shot put and Power Lifting are just several sports in which upper body power may enhance performance. The only prerequisite for conducting the BPP test is that college age male and female lifters should be able to properly execute a 61.4 kg (135 pound) or 25 kg (55 pounds), respectively, using proper form and technique. For training purposes, coaches and fitness trainers could acquire pre and post-test measures of BPP to assess the overall effectiveness of training programs specifically designed to improve the collective upper body power of the chest, shoulders, and triceps.
A slight modification of the BPP test (ie, perhaps a heavier weight) might even be considered for the National Football League Scouting Combine instead of the repetitions to failure test currently used. Lifting a standardized load of 102.3 kg (225 pounds) as many times as possible seems to logically assess localized muscle endurance or perhaps, at best, be predictive of absolute strength; whereas, power is most likely the fitness component of greatest interest. Determining how fast an athlete can move 102.3 kg (or more) may be of greater interest to coaches than simply determining the maximum lifting frequency of a fixed load. Care must be incorporated to insure tightly controlled testing and if reliability can be demonstrated, the BPP test may be considered a valid method of assessing the power of the collective musculature associated with bench-pressing movements.
We are grateful to the 43 dedicated male and female Kinesiology majors who served as subjects in this study. In addition, we thank Chris Jeansonne for his participation in the early development of the research design and his involvement in the data collection.
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