Dose–Response Relationships of Resistance Training in Healthy Old Adults: A Systematic Review and Meta-Analysis

Abstract

BackgroundResistance training (RT) is an intervention frequently used to improve muscle strength and morphology in old age. However, evidence-based, dose–response relationships regarding specific RT variables (e.g., training period, frequency, intensity, volume) are unclear in healthy old adults.ObjectivesThe aims of this systematic review and meta-analysis were to determine the general effects of RT on measures of muscle strength and morphology and to provide dose–response relationships of RT variables through an analysis of randomized controlled trials (RCTs) that could improve muscle strength and morphology in healthy old adults.Data SourcesA computerized, systematic literature search was performed in the electronic databases PubMed, Web of Science, and The Cochrane Library from January 1984 up to June 2015 to identify all RCTs related to RT in healthy old adults.Study Eligibility CriteriaThe initial search identified 506 studies, with a final yield of 25 studies. Only RCTs that examined the effects of RT in adults with a mean age of 65 and older were included. The 25 studies quantified at least one measure of muscle strength or morphology and sufficiently described training variables (e.g., training period, frequency, volume, intensity).Study Appraisal and Synthesis MethodsWe quantified the overall effects of RT on measures of muscle strength and morphology by computing weighted between-subject standardized mean differences (SMDbs) between intervention and control groups. We analyzed the data for the main outcomes of one-repetition maximum (1RM), maximum voluntary contraction under isometric conditions (MVC), and muscle morphology (i.e., cross-sectional area or volume or thickness of muscles) and assessed the methodological study quality by Physiotherapy Evidence Database (PEDro) scale. Heterogeneity between studies was assessed using I2 and χ2 statistics. A random effects meta-regression was calculated to explain the influence of key training variables on the effectiveness of RT in terms of muscle strength and morphology. For meta-regression, training variables were divided into the following subcategories: volume, intensity, and rest. In addition to meta-regression, dose–response relationships were calculated independently for single training variables (e.g., training frequency).ResultsRT improved muscle strength substantially (mean SMDbs = 1.57; 25 studies), but had small effects on measures of muscle morphology (mean SMDbs = 0.42; nine studies). Specifically, RT produced large effects in both 1RM of upper (mean SMDbs = 1.61; 11 studies) and lower (mean SMDbs = 1.76; 19 studies) extremities and a medium effect in MVC of lower (mean SMDbs = 0.76; four studies) extremities. Results of the meta-regression revealed that the variables “training period” (p = 0.04) and “intensity” (p < 0.01) as well as “total time under tension” (p < 0.01) had significant effects on muscle strength, with the largest effect sizes for the longest training periods (mean SMDbs = 2.34; 50–53 weeks), intensities of 70–79 % of the 1RM (...

Physical Activity Intervention Effects on Physical Function Among Community-Dwelling Older Adults: A Systematic Review and Meta-Analysis

“…We found that more repetitions of resistance exercise, but not number of sets, was associated with larger intervention effects. Other recent meta-analyses examining muscle strength outcomes with resistance training suggest that number of sets does not significantly impact strength gains among older adults (Borde, Hortobágyi, & Granacher, 2015; Silva, Oliveira, Fleck, Leon, & Farinatti, 2014). However, both meta-analyses examined studies with healthier samples.…”

“…Some meta-analyses focused only on frail populations (Chou et al, 2012; de Vries et al, 2012; Gine-Garriga et al, 2010) or only on cognitively impaired populations (Gates, Fiatarone Singh, Sachdev, & Valenzuela, 2013; Potter, Ellard, Rees, & Thorogood, 2011), while others excluded studies with participants with chronic illnesses common among older adults (Tschopp, Sattelmayer, & Hilfiker, 2011), limiting generalizability of study findings. Several prior meta-analyses restricted analyses to specific PF outcomes, such as balance (Howe et al, 2011; Orr, 2010), gait speed (Lopopolo et al, 2006), limb strength (Borde, Hortobágyi, & Granacher, 2015; Raymond, Bramley-Tzerefos, Jeffs, Winter, & Holland, 2013), or cardiorespiratory fitness (Lemura, von Duvillard, & Mookerjee, 2000). Additionally, two meta-analyses combined measures of PF with measures of disability (Gu & Conn, 2008; Liu & Latham, 2011).…”

Lower-extremity resistance training on unstable surfaces improves proxies of muscle strength, power and balance in healthy older adults: a randomised control trial

“…Balance training for example, positively affects static/dynamic steady-state and proactive balance in older adults [6]. Likewise, resistance training has positive effects on measures of muscle strength [7] and balance [8] in older adults. Combinations of resistance and balance training describe in general a consecutive order, where resistance and balance exercises are executed within the same training session or within the same training block.…”

Efficacy of Age-Specific High-Intensity Stretch-Shortening Contractions in Reversing Dynapenia, Sarcopenia, and Loss of Skeletal Muscle Quality

“…Undeniably, it is the skeletal muscle contractions and the activities that coincide with this type of stimulus that are of the high-intensity nature, which is predominantly neglected as we age. High-intensity exercise training, specifically "resistance-type exercise" training (RTET) that typically is conducted at intensities ≥ 70-85% of one repetition maximum, has been recommended for enhancing skeletal muscle mass and strength in healthy and older individuals [73][74][75][76]. While there may be exercise prescription concerns for individuals with specific risk factors and those with comorbidities, prescribing this mode of exercise and the overall execution of these high-intensity skeletal muscle contractions are not contraindications by themselves; however, medical and professional oversight is warranted and advised for aged populations, as is with all populations undergoing this type of resistance exercise training.…”