Effect of Squats and Plyometric on Vertical Jump
Adams, K., O'Shea, J.P., O'Shea, K.L., Climstein, M. (1992). The effect of six weeks of squat, plyometric and squat-plyometric training on power production. Journal of Applied Sports Science Research. 6(1): 36-41.
Also see Vertical Jump Calculator.
It is generally agreed athletes should complete a general conditioning program before incorporating plyometrics. The National Strength and Conditioning Association suggests athletes should be strong in the squat before beginning a lower body plyometric program. In addition, high intensity plyometrics should not be performed year round (NSCA, 2000).
*Lift off to maximum vertical velocity (transition until maximum vertical velocity)
Varying Velocities and Forces
Ideal exercise stimulus for both strength and power to achieve optimal performance gains includes varying forces and velocities (as in a periodized program):
- high force / low velocity
- low force / high velocity
- high force / high force
Baker D (1996). Improving vertical jump performance through general, special, and specific strength training: A brief review. J Strength Cond Res. 10131-136
Harris GR, Stone MH, O'Bryant HS, Prouix CM, Johnson RL (2000). Short-term performance effects of high speed, high force, or combined weight training methods. J Strength Cond Res. 14(1):14-20.
Increase of Force or Speed?
An increase in power comes from higher force of training and not from a higher velocity of training.
Bompa T, Carrera M (2015) Conditioning Young Athletes. Human Kinetics.
Contrasting Load Enhance Power
Contrasting loads and/or exercises results in short-term enhancement of power output. Alternating sets of a strength exercise and load (>85% 1RM) with sets of a power exercise and/or load (30-45% 1RM).
Baker, Daniel (2001), A series of studies on training of high-intensity muscle power in rugby league football players, Journal of Strength and Conditioning Research, 15(2), 198-209.
Smilios I, Pilianidis T, Sotiropoulos K, Antonakis M, Tokmakidis SP (2005). Short-term effects of selected exercise and load in contrast training on vertical jump performance, Journal of Strength and Conditioning Research, 19(1):135-9
Mangine (2008) compared a heavy resistance training program (HR: 6-8 traditional exercises) to a program combining ballistic and heavy weight training (COM: 4-6 traditional + 2 ballistic exercises). 17 men (age 21.4 +/-1.7 years) were randomly assigned to 1 of 2 of the training programs, both performed assigned exercises 3 times a week.
- Both groups increased squat 1-rep max (COM = 15.2%; HR = 17.3%) with no significant difference between groups.
- The COM group increased jump squat peak power whereas the HR group experienced a reduction (COM = 5.4%; HR = -3.2%).
- The COM group increased 1-rep max bench press significantly more the HR group (COM = 11.6%; HR = 7.1%).
- Both groups increased plyometric push-up peak power (COM = 8.5%; HR = 3.4%) with no significant difference between groups.
- Both groups increased lean body mass with no significant difference between groups.
Results of this study suggest the inclusion of ballistic exercises into a heavy resistance training program can increase 1RM bench press and lower-body power.
Mangine GT, Ratamess NA, Hoffman JR, Faigenbaum AD, Kang J, Chilakos A (2008). The effects of combined ballistic and heavy resistance training on maximal lower and upper body strength in recreationally trained men. J Strength Cond Res. 22(1):132-139.
Optimal Workload for Power Training
Wilson (1993) suggested training at 30%-60% improves both force and velocity (aka: explosive strength). Greater workloads improve primarily force. The optimal loads for power training vary according to exercise.
Stock (2010) found bench press power output increases from 10% to 50% of 1-RM and then decrease from 50% to 90% 1-RM.
Jandacka (2001) found that loads at 30 and 50% of the 1RM resulted in greater mean bench press power output computed from the acceleration phase of the lift than did all other loads.
Siegel (2002) reported maximal power output with loads of 40-60% of 1RM for the bench press and 50-70% of 1RM for the squat.
Cormie (2007) found that the optimal loads were 0% of 1RM for the jump squat, 56% of 1RM for the squat, and 80% of 1RM for the power clean.
For power pulls, the optimum weight results in 10-20% greater power output as compared to 1 RM.
|Pulls: Power Output (W/Kg)|
|70-80 % 1 RM||55-65||33-45|
Cormie P1, McCaulley GO, Triplett NT, McBride JM (2007). Optimal loading for maximal power output during lower-body resistance exercises. Med Sci Sports Exerc. 39(2):340-9.
Jandacka D, Uchytil J. (2011). Optimal load maximizes the mean mechanical power output during upper extremity exercise in highly trained soccer players. J Strength Cond Res. 25(10):2764-72.
Siegel JA1, Gilders RM, Staron RS, Hagerman FC (2002). Human muscle power output during upper- and lower-body exercises. J Strength Cond Res. 16(2):173-8.
Stock MS, Beck TW, Defreitas JM, Dillon MA (2010). Relationships among peak power output, peak bar velocity, and mechanomyographic amplitude during the free-weight bench press exercise. J Sports Sci. 28(12):1309-17.
Wilson GJ, Newton RU, Murphy AJ, Humphries BJ (1993). The optimal training load for the development of dynamic athletic performance. Med Sci Sports Exerc. 25(11):1279-86.
Muscular Hypertophy & Force Development
Strength development may be associated with muscle hypertrophy whereas force development may be related with alterations in neural activation (Sale 1988; Hakkinen 1989). However, hypertophy of Type II fibers may also improve force development (Hakkinen & Komi 1986).
Jumping from heights greater than 40 cm (16") does not seem to produce greater force development since a deeper flexion is required for shock absortion which may disapate elastic energy and slow the speed of recoil (Kreighbaum, 1996). A height of no more than 20 cm (8") has been suggested for reduced risk of injury (Kreighbaum, 1996). Other experts suggest a 46 cm (18") bench height is optimal for a high jump height at a low injury occurrence. Also see Stretch-shortening Cycle.
A greater contractile force was achieved from a quick bounce-jump executed as soon as possible after landing from a drop-jump as compared to a deeper knee bend jump (Kreighbaum, 1996). Dr. Michael Yessis states the jump must be executed in 0.15 seconds or less. (Fitness Management, Oct 1999)
Strength, Velocity, Progress, and Volume
- It appears that in the early stages of training, increased strength gains contribute to maximum power output.
- As potential strength gains diminish, then other velocity-oriented means contribute to maximum power output.
- A diminished relationship between changes in strength and changes in maximum power must occur with increased training experience.
- Training volume has more impact on power than strength.
Baker, Daniel (2001), The effects of concurrent training on the maintenance of maximal strength and power in professional and college-age rugby league football players, Journal of Strength and conditioning Research, 15(2), 172-177.
Explosive exercise can enhance power production whereas regular slow exercise may impair power development.
Hakkinen K, Myllyla E (1990). Acute effects of muscle fatigue and recovery on force production and relaxation in endurance, power, and strength athletes. J Sports Med Phys Fitness. 30: 5-12.
Viitasalo JT, Aura O (1984). Seasonal fluctuations of force production in high jumpers. Can J Appl Sports Sci. 9: 209-213.
To maximize force production at a joint, it is not enough to just do activities which are task specific movements (to allow neural drive and multi joint coordination to develop). Specific movements at the correct velocity must be performed. An increase in strength does not transfer to all speeds which the movement was performed. The greatest increases in strength occur near or below the velocity of the exercise.
Behm & Sale (1993)
- subjects trained at 1.05, 3.14, 5.24 rad/sec, 8 weeks
- slow speed training group showed greatest strength increases at slow speed test
- fast speed training group showed greatest strength increases at fast speed test
- middle speed training group showed similar strength increases at all speeds
Behm & Sale (1993); Narici et. al., (1989)
- subjects who trained at a slow speed (36 degrees / second) only achieved increases in force at the slow training speed
- subjects who trained at a fast speed (108 degrees / second) achieved increases in force all testing speeds (0-108 degrees / second)
- Comparison of explosive jump training and heavy resistance weight training on rate of rapid increase in force and EMG during maximal isometric contractions.
- resistance training caused the greatest increase in peak force
- explosive training caused the greatest increase in rate of force development and more rapid EMG onset
Theories of velocity specificity training:
- increase in neural activation pattern
- increased synchronization of motor units
- development of a motor program for the rapid movement
- changes in contractile properties of muscle, specific for the speed trained
Untrained vs Trained Depth Jump
During a depth jump of 110 cm, an untrained individual responds with a period of inhibition during the eccentric phase after landing (stretch load). In contrast, a trained jumper responds with a period of facilitation, or increased agonist activation (Schmidtbleicher & Gollhofer, 1982).
Premovement Silence (PMS)
Just prior to ballistic movements, agonist muscles may exhibit a premovement silence (PMS) where there is little or no motor unit activity. Increased frequency of PMS may be learned; a neural adaptation to high velocity training. The PMS may increase peak force and the rate of force development of ballistic movement by inducing a brief stretch-shortening cycle. Furthermore, the brief silent period may bring motoneurones into a non-refractory state increasing their potential to be more readily recruited and to be able to execute higher firing rates.
Ski Jumper's Peak Force
Komi (1984) found although ski jumpers were able to achieve peak leg extension force more rapidly than untrained men, they did not have greater leg extension peak force as untrained men.
Beginner and Intermediate
At beginner and intermediate training levels, power exercises like the snatch and cleans & jerk typically do not exceed 5 repetitions. No more than 6 repetitions are usually performed on partial power exercises such as hang cleans and hang snatch. This allows them to focus on exercise mechanics (AKA: form) with less chance of injury.
Advanced and Elite
At advanced and elite training levels, rep ranging between 1-3 reps are typically performed for the Clean or the Clean and Jerk.
Glenn Pendley explains:
"Most who try sets of 5 on the clean and jerk with any decent load quickly abandon the notion that the competitive lifts can be trained with high reps. Most (maybe all?) accomplished lifters use sets of 1-3 (reps) almost exclusively for a reason. And singles or doubles are probably far more popular than triples."