Effects of moment of inertia on restricted motion swing speed

In many sports, the maximum swing speed of a racket, club, or bat is a key performance parameter. Previous research in multiple sports supports the hypothesis of an inverse association between the swing speed and moment of inertia of an implement. The aim of this study was to rigorously test and quantify this relationship using a restricted swinging motion. Eight visually identical rods with a common mass but variable moment of inertia were manufactured. Motion capture technology was used to record eight participants' maximal effort swings with the rods. Strict exclusion criteria were applied to data that did not adhere to the prescribed movement pattern. The study found that for all participants, swing speed decreased with respect to moment of inertia according to a power relationship. However, in contrast to previous studies, the rate of decrease varied from participant to participant. With further analysis it was found that participants performed more consistently at the higher end of the moment of inertia range tested. The results support the inverse association between swing speed and moment of inertia but only for higher moment of inertia implements

Methods for estimating moment of inertia of cricket bats

Mass moment of inertia is a key inertial property of cricket bats and should be used in selection to optimise performance. Players currently rely on a subjective assessment of how the bat feels when swung supported only by a value for bat mass from the manufacturer. This reliance on a subjective assessment is because the moment of inertia of a bat typically requires a pendulum method to measure with sufficient accuracy. In this study, two methods for estimating moment of inertia were tested. The hypotheses were that (1) an acceptable estimate of moment of inertia could be calculated using a beam model approach, and (2) the inertial property first moment could act as a proxy measure for moment of inertia. Experimental values for moment of inertia were obtained using a pendulum method. The two-section beam model showed an error of 0.43–0.53% between model and experimental values based on a Root Mean Square Error of 0.0017 kg m2. First moment data were generated on 5005 bats spread across eight bat shapes. A correlation was shown between the measured value of first moment and the beam model value of moment of inertia, with an R2 value > 0.992 for all bat shapes. This study showed that a two-section beam model and first moment method for estimating cricket bat moment of inertia could be used to improve bat selection

The Effects Of Various Warm-Up Devices on Bat Velocity and Trajectory in Collegiate Baseball Players

Purpose: The purpose of this study was to examine the effects of various weighted warm-up devices on standard baseball bat velocity and trajectory in collegiate baseball players. Methods: Three, right-handed hitters (mean age= 19.3yrs ±1.5yrs; height= 1.74m±.13m; mass=81kg ±20.4kg; baseball experience=14.2 ±1.3) volunteered for this study. Maximal bat velocity was obtained by swinging the 30oz standard bat for the control condition. Participants were then instructed to perform a general and specific warm-up with each of the weighted bats (standard bat with 16oz donut ring (46oz total) and standard bat with 24oz power sleeve (54oz total)) on separate days. Following the warm-up procedures, participants were instructed to swing 3 times with the 30oz standard bat for maximal velocity while impacting the ball resting on the tee located belt-high and in the middle of home plate.Results: No significant differences were revealed by Shewart Chart method for baseball bat velocity or trajectory. Also, it was observed that all participants swung the bat at its lowest point in its trajectory for all conditions. Conclusion: Based upon no changes in the dependent variables in the population tested, Division II collegiate athletes can choose any of the warm-up devices investigated because no deleterious effects were observed

The Effects Of Various Warm-Up Devices on Bat Velocity and Trajectory in Collegiate Baseball Players

Purpose: The purpose of this study was to examine the effects of various weighted warm-up devices on standard baseball bat velocity and trajectory in collegiate baseball players. Methods: Three, right-handed hitters (mean age= 19.3yrs ±1.5yrs; height= 1.74m±.13m; mass=81kg ±20.4kg; baseball experience=14.2 ±1.3) volunteered for this study. Maximal bat velocity was obtained by swinging the 30oz standard bat for the control condition. Participants were then instructed to perform a general and specific warm-up with each of the weighted bats (standard bat with 16oz donut ring (46oz total) and standard bat with 24oz power sleeve (54oz total)) on separate days. Following the warm-up procedures, participants were instructed to swing 3 times with the 30oz standard bat for maximal velocity while impacting the ball resting on the tee located belt-high and in the middle of home plate.Results: No significant differences were revealed by Shewart Chart method for baseball bat velocity or trajectory. Also, it was observed that all participants swung the bat at its lowest point in its trajectory for all conditions. Conclusion: Based upon no changes in the dependent variables in the population tested, Division II collegiate athletes can choose any of the warm-up devices investigated because no deleterious effects were observed

The effect of moment of inertia on the speed of swung implements.

The maximum swing speed of an implement is an important performance parameter in many sports. It is understood that moment of inertia (MOI) has an effect upon the swing speed of an implement and numerous studies have found a similar rate of swing speed decay (n). These studies considered different movements which suggested that skill was less important than physique to the relationship between swing speed and MOI. The aim of this project was to quantify this relationship and to determine whether the physical characteristics of a participant can be used to predict their swing speed performance. A series of eight visually identical rods with varied MOI were swung in a heavily restricted, maximal motion and trials were recorded with a motion capture system. The results found that swing speed decreased as MOI increased. It was also found that if n was assumed to be constant, the maximum work done by a participant was strongly and significantly related to their swing speed. The relationship between work done and swing speed was used to create a model to predict swing speed for an implement with a specific MOI. This model was validated for a new set of participants performing the same restricted motion and all measured data fell within the confidence intervals of the predictions. The ecological validity of the model was tested in an analysis of the swing speed of tennis groundstrokes. An impact model was used to analyse the effect of changing MOI on ball speed. It was discovered that there is an optimum MOI that produces a maximum ball speed and that this optimum MOI is dependent upon n. This makes the customisation of equipment a realistic possibility. A simple method for measuring n in a non-laboratory environment is proposed that will enable the customisation process to take place