Effects of resistance training intensity on muscle quantity/quality in middle‐aged and older people: a randomized controlled trial

Abstract

Background A sarcopenia diagnosis is confirmed by the presence of low muscle quantity or quality under the 2018 revised definition by the European Working Group on Sarcopenia in Older People 2. Imaging methods [i.e. magnetic resonance imaging (MRI)], dual‐energy X‐ray absorptiometry (DXA), and bioelectrical impedance analysis are tools to evaluate muscle quantity or quality. The present study aimed to investigate whether and how low‐intensity and moderate‐intensity resistance training improved both muscle quantity and quality measured by MRI, DXA, and segmental bioelectrical impedance spectroscopy (S‐BIS) in middle‐aged and older people. Methods A single‐blind, randomized, controlled trial was conducted. Community‐dwelling people aged 50–79 years were randomly allocated to no exercise (no‐Ex), low‐intensity exercise (low‐Ex), and moderate‐intensity exercise (moderate‐Ex) groups. Participants in the exercise groups performed resistance training for 24 weeks, with loads of 40% and 60% of one repetition maximum in the low‐Ex and moderate‐Ex groups, respectively. Cross‐sectional area (CSA), lean mass, and muscle electrical properties on S‐BIS were used to determine the effects of training interventions on muscle quantity and quality of the lower limbs. Results Fifty participants (no‐Ex 17, age 63.5 ± 8.5 years, women 47.1%; low‐Ex 16, age 63.6 ± 8.1 years, women 50.0%; moderate‐Ex 17, age 63.5 ± 8.3 years, women 52.9%) completed the 24 week exercise intervention. For the primary outcome, significant intervention effects were found in thigh muscle CSA on MRI between the moderate‐Ex and no‐Ex groups (+6.8 cm2, P < 0.01). Low‐Ex for 24 weeks only increased quadriceps CSA (+2.3 cm2, P < 0.05). The per cent change of thigh muscle CSA (+7.0%, P < 0.01) after 24 week moderate‐Ex was higher than that of leg lean mass on DXA (+2.3%, P = 0.088). Moderate‐Ex for 24 weeks also improved S‐BIS electrical properties related to muscle quantity and quality, including the intracellular resistance index (+0.1 cm2/Ω, P < 0.05), membrane capacitance (+0.7 nF, P < 0.05), and phase angle (+0.3 deg, P < 0.05); their changes were positively correlated with that of thigh muscle CSA (P < 0.01). Conclusions Resistance exercise with moderate intensity improved muscle quantity and quality measured by MRI and S‐BIS, whereas that with low intensity only increased muscle quantity in middle‐aged and older people. The comparisons among the responses to exercise between the assessment methods indicate the greater value of MRI and S‐BIS to measure changes of muscle quantity and quality than of lean mass measured by DXA for assessing the local effects of resistance training.

Effects of Quercetin Glycoside Supplementation Combined With Low-Intensity Resistance Training on Muscle Quantity and Stiffness: A Randomized, Controlled Trial

“…Of note, the effects of QG supplementation on muscle quantity was observed only in whole-body lean mass on DXA, not in thigh muscle CSA on MRI (Supplementary Table 3). Our previous report showed that muscle CSAs on MRI would be more sensitive for detecting local muscle hypertrophy by resistance training than lean mass on DXA (10), which was confirmed in the present study; the changes in thigh muscle CSA (+5.6%) were higher than those of wholebody lean mass (+2.0%) by exercise alone during the 24-week intervention. In contrast, nutritional interventions may exert systemic effects on skeletal muscle, so that lean mass on DXA would be more appropriate for evaluating these effects.…”

“…A systematic review suggested a dose-response relationship between resistance training intensity and the increase in muscle mass in elderly people ( 9 ). Our previous study also showed that a higher intensity of resistance exercise was more effective for improving both muscle quantity and quality ( 10 ). In fact, we found that low-intensity, 40% 1-repetition maximum (1-RM) exercise for 24 weeks could improve muscle quantity, but not muscle quality, although both were improved by 60% 1-RM exercise for the same duration ( 10 ).…”

“…Our previous study also showed that a higher intensity of resistance exercise was more effective for improving both muscle quantity and quality ( 10 ). In fact, we found that low-intensity, 40% 1-repetition maximum (1-RM) exercise for 24 weeks could improve muscle quantity, but not muscle quality, although both were improved by 60% 1-RM exercise for the same duration ( 10 ). Recently, the guideline of the Asian Working Group for Sarcopenia suggested that nutritional supplementation has a supportive role in the effects of exercise on muscle mass and function ( 11 ).…”

“…Participants performed resistance exercise programs 3 days per week (every Monday, Wednesday, and Friday) for 24 weeks, as previously reported ( 10 ). Briefly, a well-trained instructor conducted the training program, which constituted a 5-min warm-up, 30-min resistance training using machines including leg extension, leg curl, leg press, and chest press, and 5-min cool-down.…”

“…1-RM was determined every 4 weeks to adjust the training weight for each participant, while during the first 2 weeks of the 24-week period, participants were instructed to achieve the appropriate forms with gradually increasing intensity. For evaluating 1-RM, the indirect method of the 1-RM test was used, as previously reported ( 10 ). Attendance and numbers of sets completed were checked by instructors to calculate the attendance rates.…”