Equipment
Ballistic
Measurement System
Ballistic Braking System
Smith machine
Objective
This
laboratory demonstrates a new concept in athletic training and testing,
ballistic resistance and also demonstrates the use of the Ballistic Measurement
System for collecting kinematic data during explosive movements.
The provision of feedback and assessment of training performance is also
addressed.
Basic
Concepts
Traditional
weight training exercises can be considered relatively non-specific to athletic
events as they are typically performed at relatively slow movement velocities
(<1 m/s for a loaded bench press) and involve a relatively large deceleration
phase towards the end of the movement range.
Ballistic exercises are substantially more specific to athletic events as
the velocity of movement is greater (approximately 5 m/s for a ballistic bench
throw) and the movements do not involve a deceleration phase towards the end of
the exercises.
There
are limitations to the performance of plyometric exercises, however, and these
include:
(i)
The high incidence of injury associated with the use of intense
plyometric exercises (eg depth jumping) due to the high impact forces
experienced during these activities;
(ii)
The limited number of exercises that can be effectively performed.
Essentially limited to lower body exercises;
and
(iii)
The lack of feedback associated with the performance of explosive power
exercises.
Research
into the expression and development of maximal muscle power has addressed these
limitations to the training of explosive performance.
Laboratory
Exercises
Task
(a) The effect of eccentric braking on impact force
Select
a subject who is involved in a sport that involves jumping and after a warm-up
have them perform three maximal jumps without use of the braking mechanism.
Record peak eccentric and concentric velocity and height of the jumps.
Ensure the safety catches are positioned at an appropriate height for
jumps. Repeat the jumps, but this
time turn the eccentric brake on. The
brake should be set so that it visibly reduces the downward velocity of the
subject. Record your results in the
following table.
|
|
Eccentric/Concentric
Velocity (m.s-1) |
Jump
Height (m) |
||||
|
|
Non-braked
Jumps |
Braked
Jumps |
Non-braked
Jumps |
Braked
Jumps |
||
|
Jump
#1 |
|
|
|
|
|
|
|
Jump
#2 |
|
|
|
|
|
|
|
Jump
#3 |
|
|
|
|
|
|
|
Mean |
|
|
|
|
|
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Discussion
Questions
1.
What effect did the brake mechanism have on the height of the jumps and the peak
eccentric and concentric velocities achieved by the jumper?
2. From you observations, what would you expect to be the effect on the ground reaction forces during landing from the weighted jumps?
Task
(b) A comparison of velocity of traditional weight training and ballistic
exercises
Use the minimum weight on the bar of the Smith machine. Recruit six volunteers to serve as subjects. After a warm-up have the subjects perform a traditional bench press and a maximal velocity ballistic bench throw. To control for possible order effects, place the subjects into two groups of three and have one group perform the traditional bench presses first, followed by the bench throws. The second group will perform the tasks in the opposite order. Record the maximal velocity of the lift for each exercise. Prior to each lift ensure the safety catches are positioned such that the subject will not be hit by the bar if it is not correctly caught.
Peak
velocity of bar
|
Subject |
Bench
Press |
Bench
Throw |
|
1 |
|
|
|
2 |
|
|
|
3 |
|
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|
4 |
|
|
|
5 |
|
|
|
6 |
|
|
|
Mean |
|
|
Discussion
Questions
1.
Which form of the bench press exercise allowed for the greatest velocity to be
realised? Why?
2. Examine the velocity - time and displacement - time graphs. User the cursors to mark where the peak in velocity occurs and then select the displacement graph. Describe where the peak in velocity occurs in terms of bar position for the throw and the press. What is the relevance of this to training for ballistic movements such as thowing or striking?
The predominant requirement in a large number of sports is explosive power. For the lower body this is perhaps best exemplified in the vertical jump. Here the muscles about the hip, knee and ankle act rapidly and with high force to produce the greatest possible velocity of the body as it leaves the ground. The jump height produced is determined purely by this takeoff velocity. This laboratory session addresses the interaction of load, velocity and power during vertical jump performance and illustrates their significance to the testing and training of human performance in general.
Strength is the ability of the muscle to exert a high force or torque at a specified velocity (Knuttgen & Kraemer, 1987) and varies for different muscle actions such as eccentric, concentric and isometric (Kraemer, 1992). Dynamic strength is often assessed using a 1 repetition maximum (1RM) test in which strength is assessed as the maximum weight the athlete can lift once through the complete movement. The development and assessment of strength has received a great deal of research attention (Atha, 1981; Berger, 1962; Hakkinen, et al., 1987; Schmidtbleicher, 1988) and the interested reader may refer to the relevant literature. Pure 1RM strength however, is a requirement of a limited number of athletic endeavours (e.g., Power Lifting). Most sports require the explosive application of force to accelerate the body, limb or implement resulting in a high velocity at the point of impact or release. This aspect of performance has been termed explosive power or speed strength (Young, 1993).
The key difference between strength and power in concentric movements is the speed of muscle action. Strength is the force that the muscle can exert and is maximized during very slow concentric muscle actions. This is due to the force velocity relationship for muscle (Figure 1.) The faster the velocity of concentric muscle action, the lower the force that can be produced (Hill, 1938). Pure 1RM strength is required in the sport of Power Lifting because there is no requirement for the weight to be lifted quickly as the athlete is attempting to lift the maximum amount of weight. This requires movement velocities which are just higher than zero. However, most human sporting activities occur at faster velocities of movement.
In terms of testing and training, velocity specific effects are apparent (Kaneko, et al., 1983; Moritani, et al., 1987; Newton & Wilson, 1993). Therefore, strength testing using heavy loads and low velocity of movement may have limited predictive ability to high speed performance. Thus, it may be much more useful to assess force and power output at or near the velocity of movement used in the event. In terms of training, a number of studies have shown limited performance improvements in explosive activities resulting from heavy strength training (Hakkinen, et al., 1985a; Wilson, et al., 1993) and it may be much more effective to train with lighter loads using explosive ballistic movements.
Figure 1. Force velocity power relationship for skeletal muscle. Vm, Pm and Fm are maximum movement velocity, maximum power output and maximum isometric force output respectively (adapted from Faulkner, et al., 1986).
A number of studies (Faulkner, et al., 1986; Hill, 1938, Newton & Wilson, 1993) have shown that mechanical power output is maximized at approximately 30% of maximum shortening velocity and a load of 30% of maximum isometric strength (MVC). Because of this relationship, the 30% MVC load has been proposed as the optimal load for the development of mechanical power (Kaneko et al., 1983; Wilson et al., 1993) and have suggested that ballistic weight training should be performed using this load. The optimal load can be determined for squat jumps by adjusting the load on the barbell until the mechanical power output is maximized.
| Load (%1RM) | Jump Power (W) | Jump Height (m) |
| Body weight only | ||
| 15 | ||
| 30 | ||
| 45 | ||
| 60 |
Plot a graph of jump height and power against load.
Vertical jump performance has been shown to respond to training which involves the athlete performing SSC movements with a stretch load greater and more rapid than to which they are accustomed. These activities have been termed plyometrics and have been found, in a number of studies, to be effective for increasing jumping ability (Adams, et al., 1992; Clutch, et al., 1983; Schmidtbleicher, et al., 1988; Wilson, et al., 1993). Plyometric training results in an increase in the overall neural stimulation of the muscle and thus force output, however, qualitative changes are also apparent. In subjects unaccustomed to intense SSC loads, there is a reduction in EMG activity starting 50-100 ms before ground contact and lasting for 100-200 ms (Schmidtbleicher, et al., 1988). Gollhofer (1987) has attributed this to a protective mechanism by the golgi tendon organ reflex acting during sudden, intense stretch loads to reduce the tension in the tendomuscular unit during the force peak of the SSC. After a period of plyometric training the inhibitory effects are reduced, termed disinhibition, and increased SSC performance results (Schmidtbleicher, et al., 1988).
| Condition | Jump Height (m) | Minimum Displacement (m) | Jump Power (W) |
| minimum dip | |||
| maximum jump height | |||
| minimum dip and maximum jump height |
Adams, K., O'Shea, J.P., O'Shea, K.L., and Climstein, M., 1992. The effect of six weeks of squat, plyometric and squat-plyometric training on power production. J. Appl. Sport Sci. Res.; 6(1): 36-41.
Armstrong, D.F., 1993. Power training: The key to athletic success. NSCA J.; 15(6):7-10.
Atha, J., 1981. Strengthening muscle. Exerc. Sport Sci. Rev.; 9:1-74.
Bauer, T., Thayer, R.E., and Baras, G., 1990. Comparison of training modalities for powerdevelopment in the lower extremity. J. Appl. Sport Sci. Res.; 4(4): 115-121.
Behm, D.G. and D.G. Sale, 1993a. Intended rather than actual movement velocity determines velocity-specific training response. J. Appl. Physiol.; 74(1): 359-368.
Behm, D.G. and D.G. Sale, 1993b. Velocity specificity of resistance training. Sports Med.; 15(6): 374-388.
Berger, R.A., 1962. Optimum repetitions for the development of strength. Res. Q.; 33:334-338.
Berger, R.A., 1963. Effect of dynamic and static training on vertical jumping. Res.Q.; 34:419-424.
Blakey, J.B. and Southard, D., 1987. The combined effects of weight training and plyometrics on dynamic leg strength and leg power. J. App. Sports Sci.Res.; 1(1): 14-16.
Bosco, C., and Komi, P.V., 1979. Mechanical characteristics and fiber composition of human leg extensor muscles. Eur. J. Appl. Physiology; 24:21-32.
Bosco, C., Komi, P.V., Pulli, M., Pittera, C. and H. Montonev, 1982. Considerations of the training of elastic potential of human skeletal muscle. Volleyball Technical Journal; 1(3):75-80.
Bosco, C., Komi, P.V., Thihany, J., Fekete, G. and P. Apor, 1983. Mechanical power test and fibre composition of human leg extensor muscles. Eur. J.Appl. Physiology; 51:129-135.
Bosco, C., 1992. Evaluation and control of basic and specific muscle behavior Part 1. Track Technique; (123): 3930-3933,3941.
Bosco, C., 1992. Evaluation and control of basic and specific muscle
behavior Part 2. Track Technique; (124): 3947-3951,3972.
Clutch, D., Wilton, M., McGown, C., and Bryce, G.R., 1983. The effect of depth jumps and weight training on leg strength and vertical jump. Res. Q.; 54(1): 5-10.
Di Brezzo, R.D., Fort, I.L., and Diana, R., 1988. The effects of a modified plyometric program on junior high female basketball players. J. Appl. Res.Coaching Athletics; 3(3): 172-181.
Duke, S., and BenEliyahu, D., 1992. Plyometrics: Optimizing athletic performance through the development of power as assessed by vertical leap ability: An observational study. Chiropractic Sports Medicine; 6(1):10-15.
Elliott, B.C., Wilson, G.J., and Kerr, G.K., 1989. A biomechanical analysis of the sticking region in the bench press. Med. Sci. Sports Exerc.; 21: 450-462.
Ettema, G.J.C., Van Soest, A.J., and Huijing, P.A., 1990. The role of series elastic structures in prestretch-induced work enhancement during isotonic and isokinetic contractions. J. Exp. Biol.; 154: 121-136.
Faulkner, J.A., Claflin, D.R., McCully, K.K., 1986. Power output of fast and slow fibers from human skeletal muscles. In: Human Muscle Power; N.L. Jones,N. McCartney, and A.J. McComas, (eds). Human Kinetics Pub. Champaign, IL., 88.
Garhammer, J., and Gregor, R., 1992. Propulsion forces as a function of intensity for weightlifting and vertical jumping. J. Appl. Sports Sci. Res.;6(3): 129-134.
Garhammer, J., 1993. A review of power output studies of Olympic and Powerlifting: Methodology, performance, prediction, and evaluation tests.J. Appl. Sports Sci. Res.; 7(2): 76-89.
Gollhofer, A., 1987. Innervations characteristics of m. Gastrocnemius during landing on different surfaces. In: Biomechanics XB; B. Jonsson, (ed). Human Kinetics Pub., Champaign, Ill. Pp701-706.
Gollhofer, A., and Kyroelaeinen, H., 1991. Neuromuscular control of the human leg extensor muscles in jump exercises under various stretch-load conditions.Int. J. Sports Med.; 12: 34-40.
Haekkinen, K., Komi, P.V. and Tesch, P.A., 1981. Effect of combined concentric and eccentric strength training and detraining on force-time, muscle fiber and metabolic characteristics of leg extensor muscles. Scand. J. Sports Sci.; 3(2): 50-58.
Haekkinen, K. and P.V. Komi, 1985a. Changes in electrical and mechanical behavior of leg extensor muscles during heavy resistance strength training. Scand. J. Sports Sci; 7:55-64.
Haekkinen, K. and P.V. Komi, 1985b. The effect of explosive type strength training on electromyographic and force production characteristics of leg extensor muscles during concentric and various stretch-shortening cycle exercises. Scand. J. Sports Sci; 7:65-76.
Haekkinen, K., Komi, P.V. and Alen, M., et al., 1987. EMG, muscle fibre and force production characteristics during a one year training period in elite weightlifters. Eur. J. Appl. Physiology; 56: 419-427.
Haekkinen, K., 1989. Neuromuscular and hormonal adaptations during strength and power training. J. Sports Med.; 29(1): 9-26.
Hatfield, F., 1989. Power - A Scientific Approach; Contemporary, Chicago.
Hill, A.V., 1938. The heat of shortening and the dynamic constants of muscle. Proceedings of the Royal Society of London, Series B; 126: 136-195.
Holtz, J., Divine, J., and McFarland, C., 1988. Vertical jump improvement following preseason plyometric training. J. Appl. Sports Sci. Res.; 2(3): 59.
Kaneko, M., Fuchimoto, T., Toji, H. and K. Suei, 1983. Training effect of different loads on the force-velocity relationship and mechanical power output in human muscle. Scand. J. Sports Sci.; 5(2): 50-55.
Knuttgen, H.G. and Kraemer, W.J., 1987. Terminology and measurement in exercise performance. J. Appl. Sport Sci. Res. 1:1-10.
Komi, P.V., Suominen, H., Heikkinen, E., Karlsson, J., and Tesch, P., 1982. Effects of heavy resistance and explosive-type strength training methods on mechanical, functional, and metabolic aspects of performance. Exercise
and Sport Biology; Komi, P.V., Nelson, R.C. and Morehouse, C.A. (eds). Human Kinetics, Champaign, IL.
Komi, P.V., 1986. The stretch-shortening cycle and human power output. In: Human Muscle Power; Jones, N.L., McCartney, N., and A.J. McComas, (eds). Human Kinetics, Champaign, Ill. Pp. 27-39.
Komi, P.V. and Haekkinen, K., 1988. Strength and Power. In The Olympic book of sports medicine. A. Dirix, H.G. Knuttgen and K. Tittel (eds), Blackwell Scientific Pub., Boston, pp. 183.
Kraemer, W.J., 1992. Involvement of eccentric muscle action may optimize adaptations to resistance training. Sports Science Exchange; 4(41).
Gatorade Sports Science Institute, Chicago. Kreighbaum, E. and K.M. Barthels, 1985. Biomechanics: A qualitative approach for studying human movement. 2nd Edition. MacMillan, New York.
Moritani, T., Muro, M., Ishida, K., and Taguchi, S., 1987. Electro-physiological analyses of the effects of muscle power training. Res. J. Phys. Ed.; 1: 23-32.
Murphy, A.J., Wilson, G.J., Pryor, J., and Newton, R.U., 1993. An investigation of the generality versus specificity concept in isometric and dynamic muscular assessment. Abstracts of the ASMF Conference; 1993, Melbourne, Australia.
Newton, R.U. and Wilson, G.J., 1993a. Reducing the risk of injury during plyometric training: The effect of dampeners. Sports Medicine, Training and Rehabilitation; 4: 1-7.
Newton, R.U. and Wilson, G.J., 1993b. The kinetics and kinematics of powerful upper body movements: The effect of load. Abstracts of the International Society of Biomechanics XIVth Congress, Paris, 4-8 July. pp. 1510.
O'Shea, K.L. and O'Shea, J.P., 1989. Functional isometric weight training: Its effects on dynamic and static strength. J. App. Sports Sci. Res.; 3(2):30-33.
Sale, D.G., 1992. Neural adaptation to strength training. In: Strength and Power in Sport. P.V. Komi (ed). Blackwell Scientific Pub., Boston, pp.249-265.
Schmidtbleicher, D. and M. Buehrle, 1983. Neuronal adaptation and increase of cross-sectional area studying different strength training methods. Biomechanics X-B; Vol 6-B, G. B. Johnson (ed). Human Kinetics Publishers, Champaign. pp. 615-620.
Schmidtbleicher, D., 1988. Muscular mechanics and neuromuscular control. In: Swimming Sci., V Int. Series Sport Sci.; B.E. Ungerechts, K. Wilke, and K. Reischle (eds). Human Kinetics, Champaign, IL, pp. 131-148.
Schmidtbleicher, D., Gollhofer, A. and U. Frick, 1988. Effects of a stretch-shortening typed training on the performance capability and Innervations characteristics of leg extensor muscles. In: Biomechanics XI-A; Vol 7-A G. de Groot et al., (eds). Free University Press, Amsterdam The Netherlands. pp. 185-189.
Schmidtbleicher, D., 1992. Training for power events. In: Strength and Power in Sport. P.V. Komi (ed.), Blackwell Scientific Pub., Boston. pp. 381-395.
Van Leemputte, M., Spaepen, A.J., Willems, E.J., Stunen, V.V., 1983. Influence of pre-stretch on arm flexion. Biomechanics VII-A; H. Matsui and K.Kobayashi (eds). Human Kinetics, Champaign, IL., 264-270.
Williams, D.R., 1991. The effect of weight training on performance in selected motor activities for prepubescent males. J. App. Sports Sci. Res.;5(3): 170.
Wilson, G.J., Newton, R.U., Murphy, A.J., and Humphries, B.J., 1993. The optimal training load for the development of dynamic athletic performance.Med. Sci. Sports Exerc.; 25(11): 1279-1286.
Young, W.B., 1993. Training for speed/strength: Heavy versus light loads. NSCA J.; 15(5): 34-42.
Young, W.B. and Bilby, G.E., 1993. The effect of voluntary effort to influence speed of contraction on strength, muscular power and hypertrophy development. J. Strength Con. Res.; 7(3): 172-178.
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