Introduction
The success of athletes in many competitive
sports is determined by the extent to which they
have developed their strength–velocity charac-
teristics: these include strength, speed and power
of muscle function. Peak expression of the func-
tional capability of the athlete requires the
maximum voluntary effort that can be achieved,
and thus depends not only on the characteristics
of the muscle, but also on the initiation of
impulses in the motor centres of the central
nervous system, on the maintenance of high
firing rates in the motor nerves, and on the coor-
dination of the activation of synergistic and
antagonistic muscles. Important muscle charac-
teristics include, in addition to muscle size itself,
the orientation of the muscle fibres, the propor-
tions of the different fibre types present, and the
amount and structure of the connective tissue.
The basics of muscle structure and function
have been reviewed in Chapter 2, and will be
discussed only briefly here. The following
characteristics of muscle are important for the
development of force and power:
1 The maximum muscular effort that can be
achieved is directly proportional to the length of
the individual sarcomeres (Faulkner & White
1990). This cannot be changed with training, but
will be influenced by joint angle, which will in
turn change the length of the muscle. In a whole
muscle, maximum force-generating capacity in
an isometric contraction is largely determined
by cross-sectional area (Maughan et al. 1983).
Adding more sarcomeres in parallel will increase
the maximum force that can be achieved, but
adding more sarcomeres in series will have no
effect on maximum force other than by shifting
the position on the length–tension relationship at
any given joint angle.
2 The maximum velocity of shortening of a
muscle is dependent on the load applied. For
single muscle fibres, the maximum velocity of
shortening, and therefore the maximum speed of
movement, is a function of the myosin adenosine
triphosphatase (ATPase) activity: this deter-
mines the rate at which ATP can be used to power
the interactions between actin and myosin. In
fast-contracting (type IIb) muscle fibres, the
maximum velocity of shortening is four times
higher than in slow-contracting (type I) fibres
(Burke & Edgerton 1975).
3 The power that can be developed by a muscle
is a linear function of the maximum ATPase
activity, and thus is closely related to the propor-
tions of the different fibre types present. Muscles
with a high proportion of type II fibres will be
able to achieve higher power outputs than those
where type I fibres predominate. Muscles of elite
sprinters typically contain more than 60% type I
fibres, whereas type I fibres predominate in the
muscles of endurance athletes (Costill et al. 1976).
4 The characteristic relationship between force,
or strength, and velocity referred to above was
described by Hill (1938). Force is greatest during
an isometric activation of the muscle, where the
applied load exceeds the force generating capac-
ity of the muscle and the velocity of shortening