Effects of resistance training concentric velocity on older adults' functional capacity: A systematic review and meta-analysis of randomised trials

Reduced levels of functional capacity in older adults are related to lower quality of life, frailty, and sarcopenia, and can increase risk of falling, fractures and hospitalisation. Resistance training is an effective method to attenuate age-related functional declines. Based on the findings that muscle power and explosive strength are strongly associated with functional performance in older adults, it has been suggested that fast-intended-velocity resistance training may elicit greater improvements in functional capacity when compared to moderate-velocity resistance training. However, currently, there is no high-quality systematic review and meta-analysis supporting this assertion. The present study compared the magnitude of functional capacity improvements following resistance training performed with fast-intentional velocity versus moderate velocity. Pubmed, Scopus, and Web of Science databases were searched from inception to January 2019. The following eligibility criteria for selecting studies was adopted: Participants aged >= 60 years; resistance training based intervention for lower limbs performed solely with slow to moderate concentric velocity (>= 2 s for each concentric phase) or solely with the intention of maximising velocity (i.e., as fast as possible); and at least one functional test for lower limbs, with pre- and post-intervention measurements. When studies employed multiple functional tests, a single (pooled) standardised mean difference was calculated and presented as combined functional capacity. In addition, functional tests were grouped accordingly to their specificity for the sub-groups meta-analyses. Fifteen studies were selected (high quality, n = 3; and pre-registered, n = 2). The results presented heterogeneity and small-studies publication bias, leading to a biased advantage for fast-intended-velocity resistance training (95%CI = 0.18, 0.65; I-2 = 45%). Short physical performance battery indicated an advantage for fast-intendedvelocity resistance training (95%CI = 0.10, 0.94; I-2 = 0%). There was no difference for timed up and go (95%CI = -0.07, 0.94; I-2 = 48%), 30-s chair stand (95%CI = -0.24, 1.39; I-2 = 71%), 5-times chair stand (95%CI = -1.63, 1.27; I-2 = 57%) stair climb (95%CI = -1.89, 2.81; I-2 = 0%), short walk (95%CI = -0.99, 0.96; I-2 = 21%) and long walk (95%CI = - 0.59, 1.00; I-2 = 0%). These results suggest that there is inconclusive evidence to support the superiority of fast-intended-velocity resistance training to improve functional capacity when compared to moderate-velocity resistance training. These results may have been influenced by the lack of high-quality and pre-registered studies, high heterogeneity, and small-studies publication bias.