Changes in muscle and joint elasticity following long-term strength training in old age
Résumé
The current investigation was designed (1) to
examine the effect of a 48-week strength training on
musculotendinous (MT) and musculoarticular (MA)
stiffness characteristics in older men and women; and (2)
to evaluate the influence of gender on stiffness behaviour
in response to such training. The training was performed
twice per week and mainly consisted of three series of 10
repetitions of calf-rise at 75% of the 3-repetition maximum. Two methods were used to perform stiffness
measurements during plantar flexion: (1) the use of
quick-release movements, allowing the calculation of
MT stiffness; (2) the application of sinusoidal perturbations to the joint, allowing the calculation of MA
stiffness. In each case, stiffness was linearly related to
torque, leading to the calculation of a normalized stiffness index (SI) as the slope of this stiffness-torque relationship: SIMT and SIMA, respectively. Results showed a
similar decrease in SIMT among older men (-27%,
P < 0.05) and women (-29%, P < 0.05) following
training. A decrease in SIMA was only observed among
women (-11%, P < 0.05). The results suggest that (1)
MT stiffness decreases following training in older individuals, counterbalancing the effect of ageing; and (2)
older men and women respond differently to the same
resistance-training stimulus in terms of MA stiffness.
Gender-related differences in MA stiffness response may
originate from passive MA elastic structures.