Quadriceps muscle electromyography activity during physical activities and resistance exercise modes in younger and older adults

Abstract

Background Understanding the root cause of the age-related impairment in muscle adaptive remodelling with resistance exercise training (RET) and developing pragmatic and accessible resistance exercise for older adults, are essential research directives. Methods We sought to determine whether indices of quadriceps muscle EMG activity in response to different modes of RET and activities of daily living (ADL), differed between 15 healthy younger (25 ± 3 years) and 15 older (70 ± 5 years) adults. On four separate days, participants completed a maximal voluntary contraction (MVC) of the knee extensors, followed by a 15 m walking task, stair climbing task (i.e. ADL) and lower-limb RET through body-weight squats (BW-RET) and seated knee extensions on a machine (MN-RET) or via elastic bands (EB-RET). Surface quadriceps electromyography (EMG) was measured throughout all tasks to provide indirect estimates of changes in muscle activity. Results MVC was significantly greater in young vs. older adults (Young: 256 ± 72 vs. Old: 137 ± 48 N·m, P < 0.001). EMG activity during all exercise tasks was significantly higher in older vs. younger adults when expressed relative to maximal EMG achieved during MVC (P < 0.01, for all ). In addition, relative quadriceps muscle EMG activity was significantly greater in EB-RET (Young: 20.3 ± 8.7 vs. Old: 37.0 ± 10.7%) and MN-RET (Young: 22.9 ± 10.3, vs. Old: 37.8 ± 10.8%) compared with BW-RET (Young: 8.6 ± 2.9 vs. Old: 27.0 ± 9.3%), in young and older adults (P < 0.001). However, there was no significant difference in quadriceps EMG between EB-RET and MN-RET (P > 0.05). Conclusions In conclusion, relative quadriceps muscle EMG activity was higher across a range of activities/exercise modes in older vs. younger adults. The similar quadriceps muscle EMG activity between EB-RET and MN-RET provides a platform for detailed investigation of the neuromuscular and muscle metabolic responses to such pragmatic forms of RET to strengthen the evidence-base for this mode of RET as a potential countermeasure to sarcopenia.

Impact of home-based squat training with two-depths on lower limb muscle parameters and physical functional tests in older adults

“…However, scholars have yet to investigate the effect of weight-bearing squat training on individual muscles of the QF. Understanding individual synergistic knee extensor muscles may clarify the underlying mechanism of physical function because individual QF muscles significantly influence activities of daily living (ADL) in older individuals 22 , 23 .…”

Comparative Study of Muscle Hardness during Water-Walking and Land-Walking Using Ultrasound Real-Time Tissue Elastography in Healthy Young People

“…These phenomena were thought to be caused by the increased intramuscular fluid content caused by repetitive muscle contractions [ 27 , 28 ], the increased intramuscular blood flow caused by increased capillary pressure and permeability, altered vascular, and extravascular osmotic gradients, which were caused by metabolite deposition in the activated muscle, or a combination of these factors [ 29 , 30 , 31 ]. The reason muscle hardness did not change after land-walking is likely due to the fact that the quadriceps muscle during walking was under less load on the muscle, as the muscle activity to maximum voluntary contraction (%MVC) was 2.3% [ 32 ] in healthy young subjects. The increase in blood flow to the lower leg caused by aerobic exercise activates the muscle venous pump and suppresses the occurrence of leg edema [ 33 ], possibly preventing muscle hardness from increasing easily.…”

Myofibrillar Protein Synthesis and Acute Intracellular Signaling with Elastic Band Resistance Exercise in Young and Older Men

“…Resistance exercise familiarization. The 12RM load was assessed as previously described (12). Briefly, the 12RM load was assessed using an elastic resistance band (PeakSupps, Bridgend, UK) with loads ranging from "light" to "very heavy" (6, 12, 20, and 28 kg at 100% elongation of manufacturer guidelines), starting with a self-selected load estimated to be ~50% of the participants' 1RM.…”