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Originally Posted by Siff
THE ENERGY COSTS OF TOO MUCH HYPERTROPHY
This might suggest that all muscle fibre hypertrophy lowers work capacity.
Hypertrophy is an adaptive response to physical stress and does offer the
benefit of increased mitochondrial surface area, which provides for more
efficient energy processes than would an increased number of mitochondria.
With a rapid increase in loading, the size of the mitochondria continues to
increase markedly, but their number decreases and the concentration of ATP
drops, thereby diminishing the partial volume of the contractile myofibrils.
The resulting energy deficit soon inhibits the formation of new structures
and the decreased amount of ATP stimulates various destructive processes
associated with decrease in the number of myofibrils. This process is
referred to as irrational adaptation.
Growth of any living structure is related to the balance between its volume
and its surface area. When muscle hypertrophy occurs, the surface of the
fibres grows more slowly than their volume and, this imbalance causes the
fibres to disintegrate and restructure in a way which preserves their
original metabolic state (Nikituk & Samoilov, 1990).
It would appear that light and medium increases in loading require less
energy, facilitate cell repair, minimise the occurrence of destructive
processes and stimulate the synthesis of new, non-hypertrophied cellular
structures. Medium loads applied with a medium rate of increase in loading
produce intense muscular development, the process in this case being
referred to as rational adaptation..
The fact that conventional isometric training improves performance in
static, rather than dynamic, exercise may be due to the different
structural effects of isometric training on the muscle fibres, muscle
cells, connective tissues and blood capillaries.
MORE ON OPTIMAL HYPERTROPHY
This work seems to corroborate the hypothesis referred to earlier that
there may be an optimum size for muscle fibres undergoing hypertrophy
(MacDougall et al, 1982; Tesch & Larsson, 1982). The importance of
prescribing resistance training regimes which produce the optimal balance
between hypertrophy and specific strength then becomes obvious. Thus, it
is not only prolonged cardiovascular training which can be detrimental to
the acquisition of strength, but multiple fairly high repetition sets of
heavy bodybuilding or circuit training routines to the point of failure may
also inhibit the formation of contractile muscle fibres.
Therefore, it is vital to monitor regularly changes in muscular structure
and function alongside changes in size and mass. In most cases the taking
of biopsies is not possible or financially practical, so that indirect
assessment of the adaptive processes is necessary. Increase in hypertrophy
of a given muscle zone may be assessed from muscle girth and skinfold
thicknesses at that site, while factors such as relative strength, maximal
strength and the strength deficit (see Ch 1) serve as useful indicators of
functional efficiency.
INDISCRIMINATE WEIGHT TRAINING
Bosco (1982a) cautions against the indiscriminate use of resistance
training that typifies much of the 'cross training' prescribed with weights
and circuits by Western personal trainers and coaches. He emphasizes that,
although heavy resistance training serves as a powerful stimulus for the
development and hypertrophy of both ST and FT fibres, the invaluable role
played by FT development can be impaired by the accompanying growth of ST
fibres, because the latter appear to provoke a damping effect on FT
contraction during fast movement.
This is due to the fact that, during high speed shortening of muscle, the
sliding velocity of ST fibres can be too slow and therefore, may exert a
significant damping effect on the overall muscle contraction. He concludes
that the central role played by the storage and release of elastic energy
by the connective tissues of the muscle complex should never be ignored in
sport specific training programmes.
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