Changes in power and force generation during coupled eccentric- concentric versus concentric muscle contraction w/ +training/age

Changes in power and force generation during coupled eccentric-
concentric versus concentric muscle contraction with training and
aging.

Eur J Appl Physiol. 2008 May;103(2):151-61.

Caserotti P, Aagaard P, Puggaard L.

Age-related decline in maximal concentric muscle power is associated
with frailty and functional impairments in the elderly. Compared to
concentric contraction, mechanical muscle output is generally
enhanced when muscles are rapidly pre-stretched (eccentric
contraction), albeit less pronounced with increasing age.

Exercise has been recommended to prevent loss of muscle power and
function and recent guidelines indicate training program for
increasing muscle power highly relevant for elderly subjects. This
study examined the differences in muscle power, force and movement
pattern during concentric-alone and coupled eccentric-concentric
contraction and selected functional motor performances before and
after 36-week multicomponent training including aerobic, strength,
balance, flexibility and coordination components in elderly males.
Vertical force, excursion, velocity, power and acceleration of the
body center of mass were measured in two standardised vertical jumps
(squatting jump, SQJ; countermovement jump, CMJ). Pre-stretch
enhancement during CMJ did not improve performance [i.e., no enhanced
maximal muscle power (P (peak)) and jump height (JH)] compared to
concentric-alone muscle contraction (SQJ).

Nevertheless, pre-stretch enhancement occurred as for similar SQJ and
CMJ maximal performance, elderly people employed lower mechanical
work, higher mean muscle power (P (mean)), shorter concentric phase
duration and shorter body center of mass displacement during CMJ.
Post training, CMJ P(peak), P (mean) and JH increased in training
group (P < 0.05) while P (peak) and JH decreased in control group
during the CMJ and SQJ (P < 0.05). In conclusion, long-term training
counteracted the age-related decline in muscle power and functional
performance observed in the control subjects, while substantial gains
in muscular performance were observed in the trained elderly.