Influence of aging on isometric muscle strength, fat-free mass and electromyographic signal power of the upper and lower limbs in women

Abstract

Background Aging is a multifactorial process that leads to changes in the quantity and quality of skeletal muscle and contributes to decreased levels of muscle strength. Objective This study sought to investigate whether the isometric muscle strength, fat-free mass (FFM) and power of the electromyographic (EMG) signal of the upper and lower limbs of women are similarly affected by aging. Method The sample consisted of 63 women, who were subdivided into three groups (young (YO) n=33, 24.7±3.5 years; middle age (MA) n=15, 58.6±4.2 years; and older adults (OA). n=15, 72.0±4.2 years). Isometric strength was recorded simultaneously with the capture of the electrical activity of the flexor muscles of the fingers and the vastus lateralis during handgrip and knee extension tests, respectively. FFM was assessed using dual-energy X-ray absorptiometry. Results The handgrip strength measurements were similar among groups (p=0.523), whereas the FFM of the upper limbs was lower in group OA compared to group YO (p=0.108). The RMSn values of the hand flexors were similar among groups (p=0.754). However, the strength of the knee extensors, the FFM of the lower limbs and the RMSn values of the vastus lateralis were lower in groups MA (p=0.014, p=0.006 and p=0.013, respectively) and OA (p=0.000, p=0.000 and p<0.000, respectively) compared to group YO. Conclusions The results of this study demonstrate that changes in isometric muscle strength in MLG and electromyographic activity of the lower limbs are more pronounced with the aging process of the upper limb.

Relative differences in strength and power from slow to fast isokinetic velocities may reflect dynapenia

“…Similar to previous studies, we found lower absolute EMG amplitude values from the VL and RF during the MVICs in the older men compared with the younger men (Table ). These differences in EMG amplitude may have been due to an age‐related decrease in the amount of excitable muscle tissue .…”

“…Thus, surface EMG provides a global assessment of muscle activation and has been used to investigate age‐related differences in muscle activation . Several previous studies have demonstrated that the EMG amplitude is similar or lower in older compared with younger adults during a maximal voluntary isometric contraction (MVIC). The effect of aging on EMG amplitude during dynamic muscle actions is equally unclear, because several studies have demonstrated age‐related decreases in EMG amplitude, while others have shown no differences .…”

Influence of Nordic Walking Training on Muscle Strength and the Electromyographic Activity of the Lower Body in Women With Low Bone Mass

“…Changes in muscle strength and the electromyographic activity of the lower limbs are pronounced during the ageing process [17]. Such changes are especially dangerous for women with low bone mass [18].…”

“…They suggest that differences between the upper and lower limbs are related to neuromuscular adaptations derived from greater activation of the upper limbs, as compared to the lower limbs. Therefore, exercises requiring more frequent activation of lower-limb muscles may be beneficial [17].…”

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“…Além disso, as alterações musculares não se manifestam de forma homogênea em todos os grupos musculares dos membros superiores e inferiores durante o processo de envelhecimento. Estudos demonstram, sobretudo nas mulheres, maiores reduções na força dos membros inferiores (Amaral et al, 2014;Amaral, Castro, Doimo, Silva, & Novo Júnior, 2015).…”