The Effect of Cardiovascular Fatigue on Performance of the Forward-Step-Down Test

The purpose of this study is to investigate the effects that a volitional maximal cardiovascular exertion test (the Bruce Treadmill Protocol) has on performance of the Forward-Step-Down (FSD) test, and to investigate how performance on the FSD test changes at multiple time points following the fatigue test.

Our hypotheses for this study are as follows:

• Null (H0): Participants will not demonstrate a change in score on the FSD test after performance of the Bruce test at any time point.
• Alternate (H1): Participants will demonstrate a change in score on the FSD test after performance of the Bruce test at one or multiple of the repeated measurements.

The FSD test has been shown to correlate with movement quality. Deficits in strength and flexibility that result in movement impairments are associated with scores on the test delineating "moderate" movement quality. Fatigue may play a role in increased injury risk, with fatigued participants in numerous studies showing compromised movement patterns that increase risk of injury. At this time, many of the screening tools used to determine the impact of fatigue on a player's ability to continue to play/practice involved dynamic or explosive movements, and rely on indicators such as femoral internal rotation or hip adduction angles at initial contact to grade movement patterns. These biomechanical indicators may be difficult for non-professional personnel to observe, limiting their use outside a clinic. There is currently no research on the role of the FSD test in assessing for changes in movement pattern that result from fatigue.

The literature currently acknowledges that fatigue results in altered movement patterns. Several studies have investigated the impact that fatigue has on performing challenging movements, such as plyometric drop jumps, cutting, jumping and running, and landing. However, with higher level assessments such as these, there is an increased risk for injury if performed while fatigued. Therefore, a lower level test, such as the FSD test, would be ideal as a safe and effective screening tool to look at the impact of fatigue stimulus (game play) on a person's movement quality. As stated above, the FSD test has been validated as a measure of movement quality, with acceptable interrater reliability. In addition, poor movement quality during the FSD test has been shown to correlate with several impairments such as hip abductor strength and poor flexibility. Existing literature discusses the impact of the hip abductors on knee position and risk for knee injury. Therefore, a functional test that assesses not only movement quality but identifies possible causes of poor movement would be ideal for preventing injury. Research has shown difference in postural balance following aerobic fatigue depending on the time since fatigue, with poor performance immediately following but improved performance 10 minutes after the fatigue stimulus was stopped. Therefore, this study will examine the FSD test at one, five, and ten minutes following the cardiovascular fatigue protocol in order to discern performance differences in movement quality related to time/recovery. These differences may be important because if the FSD test can be used as a screening tool to examine a person's fatigue level, it is important to also know the appropriate time to use the test in order to get accurate results.