The story starts with rats and a simple experiment. It ends with a remarkable training system that can improve your athletes’ vertical leap three to five inches in only five weeks.
It was in 1968 that we began training rats to jump. The goal – develop a reliable way to measure an animal’s explosive leg power. The original intent was to develop an anaerobic model for animals to assess the effects of steroid usage on performance and changes in vital organs such as the heart, kidney and liver (Brown and Pilch, 1972). Hoping to develop an efficient means of measuring as well as training rodents, we developed a special high-jump system and were able to train rats to jump 2.5 feet. That’s roughly the same as a human jumping 30+ feet. Putting theory to practice, we focused our research efforts on humans, by seeing if previous experiments could help athletes increase vertical jump and explosive power by incorporating both mind and body. But, more about our experiments after we discuss how others have trained athletes to increase explosive power.
Few would argue that the development of explosive power continues to be a major ingredient in competitive sports. There are numerous factors, techniques and pieces of equipment designed to increase explosive power using vertical jump as the criterion measure of performance. Let’s review a few of the studies that used various techniques to improve athletes’ explosive power. Hannam et al (1988) used plyometric training to increase vertical jump .5 to 2.5" among women basketball players. Data from Adams et al (1992) showed an increase of 3.3 cm in vertical jump after seven weeks of squats compared to a 3.81 cm increase in a matched group using three plyometric drills twice a week for six weeks. In his study, a third group that combined weight training with plyometrics increased vertical jump by over 10 cm. Using a wet vest in a hypergravity environment, Bosco (1985) demonstrated a 9 cm gain in vertical jump in elite track athletes using isotonic resistance. Kokonen and co-workers (1988) observed a 2.3 cm increase in vertical jump after isokinetic metatarsal joint strength training. Comparing two different systems, Blattner and Noble (1979) showed equal improvements in vertical jump using either isokinetics or plyometrics. These studies showed that plyometric, isotonic, isokinetic, and classical weight training (e.g., squats), and wet vest all utilized physical methods to increase vertical jump from 1 to 10 cm. but failed to incorporate our greatest resource – the power of the mind.
There are several factors or problems creating the controversy over which training method is most effective in increasing explosive power. The method of testing as well as training is greatly affected by motivation. Singer et al (1968) presented a strong argument that an athlete may improve performance by increasing motivation. One of the ways in which motivation can be increased during testing and training is through intrinsic reward (Singer, 1979). The athlete must feel as though he or she has attained a goal. The reward can vary from money to immediate positive feedback, which in turn increases motivation (Vallerand, 1983). In this manner positive performance is reinforced and corrections can be made to reverse negative performance.
The standard procedure for testing vertical jump is through slapping a ruler positioned on a wall or displacing a horizontal vane. However, these procedures may not be transferable to on-the-field performance. Goal specificity is critical for testing and training vertical jump to improve performance in game related conditions. Several authors have demonstrated that the specificity of the task is critical to improved performance. In a review of 100 studies, Locke (1968) confirmed his original hypothesis that specific, difficult and challenging goals lead to increased performance.
An important component of goal setting is the feedback provided. Smoll (1972) showed that precise feedback will enhance performance compared to general comments, such as, "you threw the duckpin ball too slow or too fast". Bilodeau and Bilodeau (1961) demonstrated the importance of immediate feedback to enhance performance, stating that knowledge of results is the strongest and most important variable controlling performance. Locke and Latham (1990) emphasized the need to have a precise feedback system in a goal-setting model. Long-term goals are too vague, and one needs immediate feedback to enhance performance. We corroborated these theories in two separate studies on strength gains using isometric training (Brown and Richardson, 1981; Brown, 1984). In the first study each subject exerted a maximum isometric hip and knee extension for 30 seconds initially without visual feedback and two days later with visual feedback. Immediately following the 30-second all-out effort maximum strength was re-evaluated.
As seen in Figure 1, above,in the visual groups the posttest values were actually greater than during non-visual feedback in the same subjects. We concluded that visual feedback provides the stimulus to maintain a greater maximum voluntary contraction (MVC) during the initial stages of a prolonged strength-requiring activity, and that a prolonged MVC does not interfere with maximal efforts and may prevent neural inhibition. The implications of this study are clear: heavy resistance warm-ups before all-out short-term athletic events may be justified. In the second study, subjects were divided into two groups. One group performed a maximum static knee extension for 30 seconds with visual feedback and the other group served as pre-post test control. The group with feedback showed a 51% and 67% increase (males and females) in leg strength after 5 weeks of training. Not only is feedback important, but Mento and colleagues showed productivity was raised 17% when goal setting was combined with feedback compared to goal setting alone. Not only are goals and feedback important, but Locke (1968) has shown that specific and hard goals resulted in better performance than simple "do your best" efforts.
We realized that to produce transferable improvements from the training room to the athletic arena, we had to incorporate task specific training routines, using challenging goals and emphasizing immediate feedback. Further, the test protocol for assessing gains in explosive power had to be related to a specific sport to be a valid procedure, not merely tapping a wall or horizontal bar. In short, we had to apply principles of both physiology of training and psychology of sport to create an attitude of "mind over gravity".
To achieve each of these goals, it became obvious that the program had to include more than a progressive physical challenge or overload, but had to be sport specific, provide both short and long term goals, and must contain a neurological and mental component that would allow the normal inhibitors of the central nervous system (glycine, and GABA), which prevent maximal effort to themselves be inhibited or overridden. Furthermore, the testing and training routines had to be injury free, a concern expressed by many trainers and authors who have used plyometric exercise.
Mind Over Gravity Concept
Now, back to the rodents. We based our concept and program upon a model developed almost 30 years ago that was used to examine the effects of an anabolic steroid (Dianabol) upon explosive power in rats (Brown and Pilch, 1972). A high jump box, developed by Dr. William Heusner and Robert Wells at Michigan State University was modified to train rats to high jump. We conditioned rats to avoid a shock by jumping to a safety platform. Starting at three inches we eventually trained the rats to jump 2 feet 6 inches – five times their height and roughly equivalent to a 30 foot human high jump. Several years later we refined and adapted the procedure for humans.
The first human studies used a crude device called Mojump that showed increases of 5" in 25 sessions. It was reported in several journals and symposia (Arnold et al, 1977; Brown et al, 1988, 1995, 1997, 1999) including the 1986 pre-Olympic Sports Science symposium in Seoul, Korea, and the 1996 and 1999 pre-Olympic Sports Science Symposia in Dallas, Atlanta, and Sydney. We termed the concept RONI (Release of Neural Inhibitions), suggesting that the normal neural inhibitors in the central nervous system (gama aminobutryic acid – GABA, and glycine) are overridden. These neural inhibitors normally function as a buffer to prevent the individual from overexerting, which might result in tearing of the muscle or tendon. However, through intense focusing coupled with goal setting, the brain prohibits itself from releasing these inhibitory neurotransmitters, thereby, allowing maximum performance. The gains we saw in our first study could not be accounted for by muscular adaptations because insufficient time had elapsed for any muscular hypertrophy to occur (Moritani and DeVries, 1979). Furthermore, the relationship between leg strength and power is only low to moderate (Berger, 1962; Mackethan and Mayhew, 1974; Smith, 1960).
We renamed the system Exploder and established a valid testing protocol to measure vertical jump in a task related manner.
Figure 2 shows the apparatus we used for both testing and training in its final form. The Exploder consists of a metal structure with an adjustable arm. Attached to the arm is a football, basketball, volleyball or other sports related object. With both feet flat on the ground, the athlete jumps for and attempts to grab the ball suspended at the pre-measured maximum jumping height, and pulls it down to chest height. A retractable cord attached to the ball allows for quick resetting between jumps. As the athlete progresses through the training program, the height of the adjustable arm can be raised in 1-2 cm increments according to the athlete’s increase in performance (see Figures 3-6).
|Figure 3: Reach Height
Figure 4-6: Two-foot take-off with arm swing grabbing ball at top of jump.
We have recently reported data from testing over 6,600 males and females from 6 to 70 years of age (Brown et al, 1999) to determine the normal decline in jumping that occurs with age and gender. It appears that female’s peak at age 19, which is four years before males. However, males begin their decline about five years sooner than females. The rate of decline among individuals who remain active in their seventh decade appears to be equivalent to the rate of decline in aerobic capacity among adults who maintain a highly active training program in aerobic activity (Trappe, 1995). We shall describe in more detail the changes that occur in both aerobic and anaerobic capacity throughout one’s lifetime in future articles at this site.
Now that a true functional (i.e., sports related) maximum jumping height is established, two unique training routines are used to accommodate either the "goal oriented" (i.e., practice makes perfect) athlete vs. the "show boat" performer who shines when the lights go up. We have reported the results of several studies using both training routines at numerous symposia in the US and worldwide (Brown et al, 1992, 1995, 1997, 1999).
The first training program for the "goal oriented" athlete requires subjects to grasp and secure the ball for 10 consecutive jumps. The second protocol (for the "show boat" athlete) is successfully completed when the athlete grasps the ball 20 out of 40 attempts. A maximum of 40 attempts are allowed per session. If subjects in either group successfully reach the workout goal, then the height of the ball is raised in .5" increments the following session. In this manner immediate feedback and reward is provided, but goal setting is more stringent in the first protocol. Motivation is enhanced by having athletes with similar vertical jumps train in pairs. Other routines have been developed which are very task specific. One routine, termed the "tap and grab" was developed by a professional NBA basketball team. You are invited to click on the attachments that provide 10-30 second movie clips of several drills that have been developed by our research team as well as trainers and coaches around the US.
You will need MPG to view these clips. Sport specific training routines have also been developed for athletes in soccer, volleyball, and American football.
Results of Research
Among our first studies with humans, we compared the effects of four different training programs, lasting five weeks, upon vertical jump and anaerobic power (Margaria-Kalamen Stairclimb test). We hypothesized that the combination of motivational jump (i.e., Exploder System) with strength and power training would bring about greater increases in power compared to either alone or other combinations of training methods. All of the subjects in this study were accomplished lifters. The group that used a combination of strength training, power lifting and Exploder showed the greatest increase in explosive power compared to either strength training or Exploder alone. It was interesting that the training program that combined strength, power and plyometrics actually showed the least improvement. Using a step down multiple regression we tried to predict the factors which accounted for the greatest improvement in jumping ability. We found that athletes who jumped fewer times using the Exploder System (because they reached they goal of 10 successful jumps with fewer repetitions) showed a greater increase in vertical jump. The correlation was extremely high (r=-.99). Therefore, repetition may not be the key to improvement in explosive power. Rather, successful repetition appears to be the key element. In a subsequent study we used 18 female high school basketball players who trained for 20 sessions over a four-week period. The group using the 10 in a row standard protocol described above increased by 1.2 inches (2.6 cm) and the modified group (20 successful jumps out of 40 attempts) increased 1.8 inches (4.0 cm). Only the modified group significantly improved their performance time in a shuttle run test. Using the combined program of strength training, power lifting and Exploder in two other studies with university and high school male and female athletes, we observed an average increase of 2.1 (4.6 cm) to 3.1 inches (6.8 cm) in 18 sessions, and an increase of 12 (26 cm) to 15 inches (33 cm) in the 5-hop test of horizontal power. Recently, we reported the results of an overload training program (female athletes wore a weighted vest) using the Exploder system (Figures 7 & 8).
Figure 7. Weighted vest with 3% Body weight
Figure 8. Jumping with weighted vest.
Using the 10-in-a-row training protocol previous described, one group wore a vest during training with 3% of body weight added onto the upper torso, whereas the other group trained normally without added resistance. Each group trained three days per week for five weeks. Each group significantly increased their vertical jump (normal group increased 6.5 cm, and overload group increased 7.5 cm), but there was no statistical difference between the groups. If the training period had been extended for another few weeks, the observed differences may have approached significance. We did observe that improvement in vertical jump was negatively correlated to initial reach height (r=-.72) and initial maximum jump height (r=-.957). This suggests that shorter individuals are more motivated during training and taller individuals rely upon their height advantage in game situations and may not feel the need to extend themselves during training.
Relevance for Coaches & Trainers
Of significance in these studies were not only the changes seen in vertical jump, shuttle run and horizontal explosiveness, but several other qualitative observations that enhance athletic performance and allow the coach and athlete to carry over the training to the arena. These observations can be summarized as follows:
- There were no injuries either during the studies or subsequent training sessions among the more than 7,000 individuals tested on the Exploder System.
- Athletes were motivated to perform up to their maximum effort due to the inherent motivational system using immediate feedback and reward.
- The emphasis in training was on achieving maximum performance using high goal setting, which was a major motivator and stimulus for improvement.
- As each athlete accumulated successful jumps, their attention or focus dramatically increased, since they knew that a miss would require that they begin over again. This significant increase in focusing most likely overrides neural inhibitors.
- Since athletes only increased their jumping height if they were successful, reward was based upon goal oriented performance not just repetition.
- The mechanics of jumping became an important teaching tool, since maximum height could only be achieved if the athlete did not drift to one side, forward or backward during each attempt. This made it extremely easy to spot and correct poor mechanics during jumping drills.
- The ability to apply sport-specific improvements to the athletic arena was emphasized with this type of training. Not only can basketball be suspended, but we are now using soccer balls for heading practice and for goalies, volleyballs for blocking drills and footballs for defensive backs and offensive ends.
- Athletes look forward to training with the Exploder System. In their words, it was like playing a game; competitive, fun and challenging.
- Using our protocol, the results we obtained were equal to or greater than other protocols in an equivalent amount of time.
- This training program uses both the mind and the body to maximize performance using all the current and accepted principles of sport psychology and physiology.
We have now established national (USA) standards for vertical jump among 6 to 70 years old males and females in a manner related to task specific sport activities. Perhaps, most significantly, we observed that repetition can produce results only when it is associated with success. We expect future training systems will be designed to incorporate goal setting, motivation, immediate feedback, and proper mechanical analysis along with proper overload and neuromuscular stimulation to produce an athlete who can develop an attitude of "mind over gravity".
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