Muscular Hypertophy & Force Development
Strength development may associated with muscle hypertrophy
whereas force development may be related with alterations in
neural activation (Sale 1988; Hakkinen, et al 1989). However,
hypertophy of Type II fibers
may also improve force development (Hakkinen & Komi 1986).
Plyometric Depth Jump Heights
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
Speed of Contraction
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 relationship between changes in
strength and changes in maximum power must occur with increased
- 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 rugdy league football players, Journal of Strength
and conditioning Research, 15(2), 172-177.
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
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
Slow Exercise Can Impair Power
exercise can enhance power production where as regular slow exercise
may impair power development.
Hakkinen K, Myllyla E (1990). Acute effects of muscle fatigue
and recovery on force proction 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.
Velocity Specificity Training
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
- Comparison of explosive jump training and heavy resistance
weight training on rate of rapid increase in force and EMG during
- resistance training caused the greatest increase in peak
- 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
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.
Power exercises like the snatch
& 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
- 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 almost exclusively for a reason. And
singles or doubles are probably far more popular than triples.
Also see Periodization