Post by anthony on Dec 30, 2010 9:20:18 GMT -5
Overload and Over-Speed Training in Baseball and Golf
Phil Cheetham tries to answer the question, "Should I swing a heavy or light weight club for practice?"
By Phil Cheetham - Posted January 6, 2007
Overload and Over-Speed Training in Baseball
Summary
Using weighted bats as training aids is an effective training method provided they are only marginally heavier or lighter (+or- 12%) than the regular bat. This article discusses how using this training method can increase your bat speed.
Similar methods should also work with golf clubs.
Introduction
Two important strength-training principles are; biomechanical specificity and progressive overload. Biomechanical specificity requires that the supplementary exercises mimic as close as possible the movement patterns of the skill being learned (Ebben, Fotsch and Hartz, 2006; Zawrotny, 2005). DeRenne and House (1993) state that the closer the supplementary exercise is to the primary activity, the greater the transfer of the training effect to the actual skill. This suggests that as many parameters as possible in the supplementary exercise should be similar to the actual skill, including, range of motion, speed, acceleration, sequence and timing. If any of these parameters stray significantly then the exercise becomes less effective. The progressive overload principle states that for a training effect to occur in the neuromuscular system, the system must be overloaded beyond its normal usage levels. The overload is normally weight or force, but the overload principle could also be extended to include overload of speed, moment of inertia, range of motion, duration or stress. The progressive part of the principle refers to the fact that as the neuromuscular system adapts to the new loads it stops changing. To counter this effect, the load must be increased again, hence the term progressive overload.
The actions of hitting and throwing a baseball are ballistic actions that occur very rapidly. Kraemer (2000) reports that baseball has a high usage of the phosphagen system to supply energy for the ballistic aspect of the swing or throw. Also since these actions take place in only a few seconds, power is of primary importance. Power can be thought of as how quickly work is done and it can also be defined as the force exerted on an object times the speed at which this force is exerted (McGinnis, 2005). One way of training to increase swing power is to use either over-weighted or under-weighted implements. The heavier implements employ the principle of overload (over-force) training to increase the strength of the athlete. The lighter implements employ the principle of over-speed training to increase the speed of the swing. One problem with overload training for a motor skill seems to be practicing with an implement that is too heavy or too light. In either case the mechanics of the swing may change and so perhaps the motor control program also. Hence the law of specificity will not be adhered to and the gains will not transfer to the actual swing. Zawrotny (2005) suggested that properly implemented overload and over-speed training is very effective because the modified implements are heavy enough to produce a conditioning effect yet light enough not to adversely affect the athlete’s mechanical skills.
The goal of this paper is to review this method in both warm-up and training, mainly in baseball batting but also in pitching, to understand if it is effective in increasing or decreasing bat or ball speed.
Warm-up with Weighted Bat
DeRenne and Branco (1986) reported on an experiment with on-deck bat velocity exercises using overloaded and under-loaded bats. A statistical analysis showed that warming up with over weight bats caused a subsequent decrement in swing speed when swinging the normal bat whereas warming up with under weight bats caused a subsequent increase in swing speed when swinging the normal bat.
In a similar but more extensive study using 60 college athletes and 13 differently weighted bats, DeRenne, Ho, Hetzler and Chai (1992) found that bats weighing within +or- 10% of the standard 30 oz. bat weight produced the highest bat velocities during subsequent swings. It was concluded that warm-up should be performed with a bat near the standard weight if the greatest swing velocity at the plate was to be achieved. Otsuji, Abe and Kinoshita (2002) tested eight men in varsity baseball and softball. Each man hit a ball 45 times in 3 sets of 15 swings. In each set the first 5 swings were with a normal, 920 g bat (control condition), the next 5 swings were with a weighted bat with an 800 g ring attached (weighted condition), and the final 5 swings were again with the normal bat (post-weighted condition). Statistical analysis showed a significant 3.3% decrease in bat speed prior to ball impact in the first swing of the post-weighted condition. The swing speed returned to normal on the second swing of the post-weighted condition. It was interesting to find that each batter felt the bat was lighter and that the swings were faster in the post-weighted condition, in fact, the first swing was actually slower but was perceived, by the athlete, as faster.
Since swinging a bat is a rotational action changing the bat weight may also change the bat’s moment of inertia. Moment of inertia is the resistance of the bat to rotational motion. It is possible to produce two implements with the same weight but different moments of inertial. The bat with the larger moment of inertia will have the weight distributed more distally. Southard and Groomer (2003) performed an experiment to determine if swinging bats in warm-up, with different moments of inertia would have an effect on pattern of motion and bat velocity in subsequent swings with a normal bat. They used large, standard and low moment of inertia bats in their study. They found that the warm-up with the larger moment of inertia bat caused both a change in swing pattern and a decrement in swing speed. This study was important because it actually showed that the movement pattern changed significantly when the bat had a much larger or smaller moment of inertia than a standard bat.
Training with Weighted Bat
DeRenne and Okasaki (1983) reported that using the power swing air resistance device or special heavy weighted bat (34oz) during training did produce a significant increase in bat velocity. The problem with their study was that there was no control group performing the same protocol with a normal bat. So it is not known if that would also have increased bat speed.
Sergo and Boatwright (1993) extended this study by adding a control group. They assigned 24 college batters randomly to 3 equal groups, each then did 20 sets of 5 swings with no more than 20 second rest between sets, 3 days per week for 6 weeks. The control group trained with a standard bat of their choice, a second group with a 62 oz, heavy bat (overload training only), and the third group alternated bats every 5 swings from the heavy bat to a very light plastic bat. This protocol attempted to vary between overload and over-speed training. Note that the heavy bat is about twice the weight of a normal bat and that only the control group trained with a normal bat. After a retest at the end of the 6-week period, all three groups found a significant improvement in bat speed with no significant difference between the methods, (control group 8.8% increase, heavy bat group 8.0% increase and alternating bat group 8.2% increase). The researchers concluded that swinging a bat 100 times per day, 3 days per week for 6 weeks significantly increases bat velocity, and that the training effect does not appear to be affected by the weight of the bat.
DeRenne, Buxton, Hetzler, and Ho (1995) disagreed with this conclusion suggesting that a reason the standard bat protocol was as good as the other two protocols was that the heavy bat was too heavy and the light bat was too light. In their study they used bats only 12% lighter and heavier than a standard bat. They studied 60 male university baseball players randomly assigned to 3 groups. Each group trained 4 days a week for 12 weeks and swung 150 times per session, with 15 sets of 10 swings and 30 second rest between sets. The control group practiced swinging a regular bat without hitting a ball. Both the “batting practice” group and the “dry swing” group used alternating heavy, light and regular bats doing 50 successive swings of each bat. Each four weeks they incrementally increased the weight of the heavy bat by 1 oz and decreased the weight of the light bat by 1 oz. The batting practice group always hit balls whereas the dry swing group just swung the bat. No additional weight training or batting practice was allowed during the experimental period. On final retest with a standard bat the batting practice group increased swing speed by 10%, the dry swing group by 6% and the control group by 1%. These were all significant increases over their own group pretest speeds. Also the batting practice and dry swing groups showed significantly more improvement than the control group and the batting practice group showed significantly more improvement than the dry swing group. This was the first study to successfully show that appropriate use of a weighted or un-weighted bat improved swing speed more than simply swinging a regular bat.
Training with Weighted Ball
It is also interesting to note that studies have been done in baseball pitching with similar results. One study by DeRenne, Buxton, Hetzler and Ho (1994) used 3 groups of 15 high school plus 60 college pitchers. The total period of training was 10 weeks. Group 1 used a heavy, light, heavy protocol for the entire training period. This was called the “combined protocol”. Group 2 used standard, heavy, standard weight balls in the first half of the training period and standard, light, standard weight balls in the second half. This was called the “block protocol”. Group 3 was the control group and used only standard weight balls. Doing 54 pitches in each session in the first three weeks, progressing to 78 pitches per session in the final three weeks provided progressive overload. No other weight training or additional throwing was allowed and no technique instruction was given. The ball weights were 4 oz (light), 5 oz (standard) and 6 oz (heavy). Both combined and block protocols produced a significant increase in ball speed over the control group, but there was no significant difference in speed between the combined and block protocols. The authors suggest that staying within 20% of the standard weight duplicates the acceleration/performance full range of motion of the specific throwing pattern and hence the success of the two protocols.
Discussion
Swinging a heavy or light bat or throwing heavy or light a ball multiple times is a form of plyometric training. Plyometric training refers to those activities that enable a muscle to reach maximal force in the shortest possible time and is designed to increase explosive muscle power. Plyometric training also helps condition the body to take better advantage of the stretch-shortening cycle of muscle. The stretch-shortening cycles employs the energy storage capabilities of the series elastic component of muscle and the stimulation of the stretch reflex to facilitate a maximal increase in muscle recruitment over a minimal amount of time (Potach and Chu, 2000). Szymanski (1998) stated that neurological adaptations would occur when using plyometric training for explosiveness. These changes may increase the number of motor units recruited, alter motor neuron firing rates, enhance motor unit synchronization and remove neural inhibition. These neural adaptations improve the amount of muscular force generated, and they occur within the first few weeks of resistance training (Harman, 2000).
Simultaneously and subsequently physiological changes are occurring due to this method of training, including hypertrophy of Type IIb muscle fibers. Type IIb muscle fibers have a higher force production, higher power output and contract faster than Type I muscle fibers (Harris and Dudley, 2000) and so are the fibers targeted appropriately by this type of training.
From the most successful research protocol by DeRenne et al. (1995) its seems the key to a successful training program for increasing bat speed is to use both heavier and lighter bats that don’t vary more than approximately +or-12% from a standard bat’s weight. This allows the swings with the adjusted bats to remain biomechanically similar to the normal swing yet still allowing for an overload in both force (heavier bat) and speed (lighter bat). This satisfies the biomechanical specificity principle of strength training. While DeRenne et al. implied that the swing motion pattern would change if the bat were too heavy; Southard and Groomer actually demonstrated that there were significant changes in the swing motion pattern.
In the DeRenne et al. training protocol the athletes also adhered to one aspect of progressive overload principle in the fact that they progressively increased the weight of the heavier bat (over force) and decreased the weight of the lighter bat (over-speed). Their initial volume of 150 swings per session is close to agreement with Potach and Chu (120 to 140 contacts per session). They did not however adhere to the Potach and Chu suggested plyometric training protocol of reducing the volume of training as the intensity increased. They kept every session at 150 swings. With this large number of repetitions, technique may have suffered in the last few swings. Also rest between repetitions and sets may have been too low with no rest between repetitions and only 30 seconds between sets.
Future studies could improve on these items and be more precise in adjusting the training volume, intensity, recovery and focusing on the maintenance of correct technique. It may also be helpful to biopsy the muscle to measure the size of the Type IIb muscle fibers to see if they have in fact hypertrophied.
Conclusion
Using weighted bats as training aids is an effective training method provided they are only marginally heavier or lighter than the regular bat used (+or-12%). Also using the heavy “donut” attachment that is still popular as a warm-up device is definitely not advised. The donut device has been shown to actually alter the swing motion pattern (Southard and Groomer) and decrease swing speed (DeRenne, 1991).
References
DeRenne, C. and Okasaki, E. (1983). Increasing bat velocity (Part 2). Athletic Journal. February, pp. 54-55.
DeRenne, C. and Branco, D. (1986). Overload or underload in your on-deck preparation? Scholastic Coach. Vol. 55. pp. 32-37.
DeRenne, C. (1991). Myths in resistance training: The donut: Does it improve bat velocity? National Strength and Conditioning Association Journal. Volume 13, Number 3, pp. 43-45.
DeRenne, C., Ho, K.W., Hetzler, R.K., and Chai, D.X. (1992). Effects of warm-up with various weighted implements on baseball bat swing velocity. Journal of Applied Sport Science Research. Vol. 6. No. 4. pp. 214-218.
DeRenne, C. and House, T. (1993). Power Baseball. West Publishing Company. Minneapolis, Minesota.
DeRenne, C., Buxton, B.P., Hetzler, R.K. and Ho, K.W. (1994). Effects of under- and overweighted implement training on pitching velocity. The Journal of Strength and Conditioning Research. Vol. 8, No. 4, pp. 247–250.
DeRenne, C., Buxton, B.P., Hetzler, R.K. and Ho, K.W. (1995). Effects of weighted bat implement training on bat swing velocity. The Journal of Strength and Conditioning Research. Vol. 9, No. 4, pp. 247–250.
Ebben, W.P., Fotsch, A. and Hartz, K.K. (2006). Multimode resistance training to improve baseball batting power. Strength and Conditioning Journal. Volume 28, Number 3, pp. 32-36.
Harris, R.T. and Dudley, G. (2000). Neuromuscular anatomy and adaptations to conditioning. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 15-23.
Kraemer, W.J. (2000). Physiological adaptations to anaerobic and aerobic endurance training programs. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 137-168.
McGinnis, P.M. (2005). Biomechanics of Sport and Exercise. Second Edition. Human Kinetics. Champaign, IL.
Otsuji, T., Abe, M., and Kinoshita, H. (2002). After-effects of using a weighted bat on subsequent swing velocity and batters’ perceptions of swing velocity and heaviness. Perceptual and Motor Skills. Vol. 94. pp. 119-126.
Potach, D.H. and Chu, D.A. (2000). Plyometric training. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 427-470.
Sergo, C. and Boatwright, D. (1993). Training methods using various weighted bats and the effects on bat velocity. Journal of Strength and Conditioning Research. 7(2), pp.115-117.
Southard, D. and Groomer, L. (2003). Warm-up with baseball bats of varying moments of inertial: Effect on bat velocity and swing pattern. Research Quarterly for Exercise and Sport. Vol. 74. No. 3. pp. 270-276.
Szymanski, D.J. (1998). The Effects of Various Weighted Bats on Bat Velocity - A Literature Review. Strength and Conditioning. June. pp. 8 – 11
Zawrotny, S. (2005). Overload / Underload Training: How It Works & Why Ball Players Should Use This Training Method. EzineArticles. Retrieved September 23, 2006, from ezinearticles.com/?Overload-/-Underload-Training:--How-It-Works-and-Why-Ball-Players-Should-Use-This-Training-Method&id=35001
Phil Cheetham tries to answer the question, "Should I swing a heavy or light weight club for practice?"
By Phil Cheetham - Posted January 6, 2007
Overload and Over-Speed Training in Baseball
Summary
Using weighted bats as training aids is an effective training method provided they are only marginally heavier or lighter (+or- 12%) than the regular bat. This article discusses how using this training method can increase your bat speed.
Similar methods should also work with golf clubs.
Introduction
Two important strength-training principles are; biomechanical specificity and progressive overload. Biomechanical specificity requires that the supplementary exercises mimic as close as possible the movement patterns of the skill being learned (Ebben, Fotsch and Hartz, 2006; Zawrotny, 2005). DeRenne and House (1993) state that the closer the supplementary exercise is to the primary activity, the greater the transfer of the training effect to the actual skill. This suggests that as many parameters as possible in the supplementary exercise should be similar to the actual skill, including, range of motion, speed, acceleration, sequence and timing. If any of these parameters stray significantly then the exercise becomes less effective. The progressive overload principle states that for a training effect to occur in the neuromuscular system, the system must be overloaded beyond its normal usage levels. The overload is normally weight or force, but the overload principle could also be extended to include overload of speed, moment of inertia, range of motion, duration or stress. The progressive part of the principle refers to the fact that as the neuromuscular system adapts to the new loads it stops changing. To counter this effect, the load must be increased again, hence the term progressive overload.
The actions of hitting and throwing a baseball are ballistic actions that occur very rapidly. Kraemer (2000) reports that baseball has a high usage of the phosphagen system to supply energy for the ballistic aspect of the swing or throw. Also since these actions take place in only a few seconds, power is of primary importance. Power can be thought of as how quickly work is done and it can also be defined as the force exerted on an object times the speed at which this force is exerted (McGinnis, 2005). One way of training to increase swing power is to use either over-weighted or under-weighted implements. The heavier implements employ the principle of overload (over-force) training to increase the strength of the athlete. The lighter implements employ the principle of over-speed training to increase the speed of the swing. One problem with overload training for a motor skill seems to be practicing with an implement that is too heavy or too light. In either case the mechanics of the swing may change and so perhaps the motor control program also. Hence the law of specificity will not be adhered to and the gains will not transfer to the actual swing. Zawrotny (2005) suggested that properly implemented overload and over-speed training is very effective because the modified implements are heavy enough to produce a conditioning effect yet light enough not to adversely affect the athlete’s mechanical skills.
The goal of this paper is to review this method in both warm-up and training, mainly in baseball batting but also in pitching, to understand if it is effective in increasing or decreasing bat or ball speed.
Warm-up with Weighted Bat
DeRenne and Branco (1986) reported on an experiment with on-deck bat velocity exercises using overloaded and under-loaded bats. A statistical analysis showed that warming up with over weight bats caused a subsequent decrement in swing speed when swinging the normal bat whereas warming up with under weight bats caused a subsequent increase in swing speed when swinging the normal bat.
In a similar but more extensive study using 60 college athletes and 13 differently weighted bats, DeRenne, Ho, Hetzler and Chai (1992) found that bats weighing within +or- 10% of the standard 30 oz. bat weight produced the highest bat velocities during subsequent swings. It was concluded that warm-up should be performed with a bat near the standard weight if the greatest swing velocity at the plate was to be achieved. Otsuji, Abe and Kinoshita (2002) tested eight men in varsity baseball and softball. Each man hit a ball 45 times in 3 sets of 15 swings. In each set the first 5 swings were with a normal, 920 g bat (control condition), the next 5 swings were with a weighted bat with an 800 g ring attached (weighted condition), and the final 5 swings were again with the normal bat (post-weighted condition). Statistical analysis showed a significant 3.3% decrease in bat speed prior to ball impact in the first swing of the post-weighted condition. The swing speed returned to normal on the second swing of the post-weighted condition. It was interesting to find that each batter felt the bat was lighter and that the swings were faster in the post-weighted condition, in fact, the first swing was actually slower but was perceived, by the athlete, as faster.
Since swinging a bat is a rotational action changing the bat weight may also change the bat’s moment of inertia. Moment of inertia is the resistance of the bat to rotational motion. It is possible to produce two implements with the same weight but different moments of inertial. The bat with the larger moment of inertia will have the weight distributed more distally. Southard and Groomer (2003) performed an experiment to determine if swinging bats in warm-up, with different moments of inertia would have an effect on pattern of motion and bat velocity in subsequent swings with a normal bat. They used large, standard and low moment of inertia bats in their study. They found that the warm-up with the larger moment of inertia bat caused both a change in swing pattern and a decrement in swing speed. This study was important because it actually showed that the movement pattern changed significantly when the bat had a much larger or smaller moment of inertia than a standard bat.
Training with Weighted Bat
DeRenne and Okasaki (1983) reported that using the power swing air resistance device or special heavy weighted bat (34oz) during training did produce a significant increase in bat velocity. The problem with their study was that there was no control group performing the same protocol with a normal bat. So it is not known if that would also have increased bat speed.
Sergo and Boatwright (1993) extended this study by adding a control group. They assigned 24 college batters randomly to 3 equal groups, each then did 20 sets of 5 swings with no more than 20 second rest between sets, 3 days per week for 6 weeks. The control group trained with a standard bat of their choice, a second group with a 62 oz, heavy bat (overload training only), and the third group alternated bats every 5 swings from the heavy bat to a very light plastic bat. This protocol attempted to vary between overload and over-speed training. Note that the heavy bat is about twice the weight of a normal bat and that only the control group trained with a normal bat. After a retest at the end of the 6-week period, all three groups found a significant improvement in bat speed with no significant difference between the methods, (control group 8.8% increase, heavy bat group 8.0% increase and alternating bat group 8.2% increase). The researchers concluded that swinging a bat 100 times per day, 3 days per week for 6 weeks significantly increases bat velocity, and that the training effect does not appear to be affected by the weight of the bat.
DeRenne, Buxton, Hetzler, and Ho (1995) disagreed with this conclusion suggesting that a reason the standard bat protocol was as good as the other two protocols was that the heavy bat was too heavy and the light bat was too light. In their study they used bats only 12% lighter and heavier than a standard bat. They studied 60 male university baseball players randomly assigned to 3 groups. Each group trained 4 days a week for 12 weeks and swung 150 times per session, with 15 sets of 10 swings and 30 second rest between sets. The control group practiced swinging a regular bat without hitting a ball. Both the “batting practice” group and the “dry swing” group used alternating heavy, light and regular bats doing 50 successive swings of each bat. Each four weeks they incrementally increased the weight of the heavy bat by 1 oz and decreased the weight of the light bat by 1 oz. The batting practice group always hit balls whereas the dry swing group just swung the bat. No additional weight training or batting practice was allowed during the experimental period. On final retest with a standard bat the batting practice group increased swing speed by 10%, the dry swing group by 6% and the control group by 1%. These were all significant increases over their own group pretest speeds. Also the batting practice and dry swing groups showed significantly more improvement than the control group and the batting practice group showed significantly more improvement than the dry swing group. This was the first study to successfully show that appropriate use of a weighted or un-weighted bat improved swing speed more than simply swinging a regular bat.
Training with Weighted Ball
It is also interesting to note that studies have been done in baseball pitching with similar results. One study by DeRenne, Buxton, Hetzler and Ho (1994) used 3 groups of 15 high school plus 60 college pitchers. The total period of training was 10 weeks. Group 1 used a heavy, light, heavy protocol for the entire training period. This was called the “combined protocol”. Group 2 used standard, heavy, standard weight balls in the first half of the training period and standard, light, standard weight balls in the second half. This was called the “block protocol”. Group 3 was the control group and used only standard weight balls. Doing 54 pitches in each session in the first three weeks, progressing to 78 pitches per session in the final three weeks provided progressive overload. No other weight training or additional throwing was allowed and no technique instruction was given. The ball weights were 4 oz (light), 5 oz (standard) and 6 oz (heavy). Both combined and block protocols produced a significant increase in ball speed over the control group, but there was no significant difference in speed between the combined and block protocols. The authors suggest that staying within 20% of the standard weight duplicates the acceleration/performance full range of motion of the specific throwing pattern and hence the success of the two protocols.
Discussion
Swinging a heavy or light bat or throwing heavy or light a ball multiple times is a form of plyometric training. Plyometric training refers to those activities that enable a muscle to reach maximal force in the shortest possible time and is designed to increase explosive muscle power. Plyometric training also helps condition the body to take better advantage of the stretch-shortening cycle of muscle. The stretch-shortening cycles employs the energy storage capabilities of the series elastic component of muscle and the stimulation of the stretch reflex to facilitate a maximal increase in muscle recruitment over a minimal amount of time (Potach and Chu, 2000). Szymanski (1998) stated that neurological adaptations would occur when using plyometric training for explosiveness. These changes may increase the number of motor units recruited, alter motor neuron firing rates, enhance motor unit synchronization and remove neural inhibition. These neural adaptations improve the amount of muscular force generated, and they occur within the first few weeks of resistance training (Harman, 2000).
Simultaneously and subsequently physiological changes are occurring due to this method of training, including hypertrophy of Type IIb muscle fibers. Type IIb muscle fibers have a higher force production, higher power output and contract faster than Type I muscle fibers (Harris and Dudley, 2000) and so are the fibers targeted appropriately by this type of training.
From the most successful research protocol by DeRenne et al. (1995) its seems the key to a successful training program for increasing bat speed is to use both heavier and lighter bats that don’t vary more than approximately +or-12% from a standard bat’s weight. This allows the swings with the adjusted bats to remain biomechanically similar to the normal swing yet still allowing for an overload in both force (heavier bat) and speed (lighter bat). This satisfies the biomechanical specificity principle of strength training. While DeRenne et al. implied that the swing motion pattern would change if the bat were too heavy; Southard and Groomer actually demonstrated that there were significant changes in the swing motion pattern.
In the DeRenne et al. training protocol the athletes also adhered to one aspect of progressive overload principle in the fact that they progressively increased the weight of the heavier bat (over force) and decreased the weight of the lighter bat (over-speed). Their initial volume of 150 swings per session is close to agreement with Potach and Chu (120 to 140 contacts per session). They did not however adhere to the Potach and Chu suggested plyometric training protocol of reducing the volume of training as the intensity increased. They kept every session at 150 swings. With this large number of repetitions, technique may have suffered in the last few swings. Also rest between repetitions and sets may have been too low with no rest between repetitions and only 30 seconds between sets.
Future studies could improve on these items and be more precise in adjusting the training volume, intensity, recovery and focusing on the maintenance of correct technique. It may also be helpful to biopsy the muscle to measure the size of the Type IIb muscle fibers to see if they have in fact hypertrophied.
Conclusion
Using weighted bats as training aids is an effective training method provided they are only marginally heavier or lighter than the regular bat used (+or-12%). Also using the heavy “donut” attachment that is still popular as a warm-up device is definitely not advised. The donut device has been shown to actually alter the swing motion pattern (Southard and Groomer) and decrease swing speed (DeRenne, 1991).
References
DeRenne, C. and Okasaki, E. (1983). Increasing bat velocity (Part 2). Athletic Journal. February, pp. 54-55.
DeRenne, C. and Branco, D. (1986). Overload or underload in your on-deck preparation? Scholastic Coach. Vol. 55. pp. 32-37.
DeRenne, C. (1991). Myths in resistance training: The donut: Does it improve bat velocity? National Strength and Conditioning Association Journal. Volume 13, Number 3, pp. 43-45.
DeRenne, C., Ho, K.W., Hetzler, R.K., and Chai, D.X. (1992). Effects of warm-up with various weighted implements on baseball bat swing velocity. Journal of Applied Sport Science Research. Vol. 6. No. 4. pp. 214-218.
DeRenne, C. and House, T. (1993). Power Baseball. West Publishing Company. Minneapolis, Minesota.
DeRenne, C., Buxton, B.P., Hetzler, R.K. and Ho, K.W. (1994). Effects of under- and overweighted implement training on pitching velocity. The Journal of Strength and Conditioning Research. Vol. 8, No. 4, pp. 247–250.
DeRenne, C., Buxton, B.P., Hetzler, R.K. and Ho, K.W. (1995). Effects of weighted bat implement training on bat swing velocity. The Journal of Strength and Conditioning Research. Vol. 9, No. 4, pp. 247–250.
Ebben, W.P., Fotsch, A. and Hartz, K.K. (2006). Multimode resistance training to improve baseball batting power. Strength and Conditioning Journal. Volume 28, Number 3, pp. 32-36.
Harris, R.T. and Dudley, G. (2000). Neuromuscular anatomy and adaptations to conditioning. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 15-23.
Kraemer, W.J. (2000). Physiological adaptations to anaerobic and aerobic endurance training programs. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 137-168.
McGinnis, P.M. (2005). Biomechanics of Sport and Exercise. Second Edition. Human Kinetics. Champaign, IL.
Otsuji, T., Abe, M., and Kinoshita, H. (2002). After-effects of using a weighted bat on subsequent swing velocity and batters’ perceptions of swing velocity and heaviness. Perceptual and Motor Skills. Vol. 94. pp. 119-126.
Potach, D.H. and Chu, D.A. (2000). Plyometric training. In: Essentials of Strength Training and Conditioning. Editors: Baechle, T.R. and Earle, R.W. National Strength and Conditioning Association. Human Kinetics. Champaign, IL. pp. 427-470.
Sergo, C. and Boatwright, D. (1993). Training methods using various weighted bats and the effects on bat velocity. Journal of Strength and Conditioning Research. 7(2), pp.115-117.
Southard, D. and Groomer, L. (2003). Warm-up with baseball bats of varying moments of inertial: Effect on bat velocity and swing pattern. Research Quarterly for Exercise and Sport. Vol. 74. No. 3. pp. 270-276.
Szymanski, D.J. (1998). The Effects of Various Weighted Bats on Bat Velocity - A Literature Review. Strength and Conditioning. June. pp. 8 – 11
Zawrotny, S. (2005). Overload / Underload Training: How It Works & Why Ball Players Should Use This Training Method. EzineArticles. Retrieved September 23, 2006, from ezinearticles.com/?Overload-/-Underload-Training:--How-It-Works-and-Why-Ball-Players-Should-Use-This-Training-Method&id=35001