The effects of different intra-set velocity loss thresholds on lower-limb adaptations to resistance training in young adults: A systematic review and meta-analysis

Abstract

Background: The level of effort seems to play a key role in determining neuromuscular adaptations; however, less is known regarding the optimal dose-response for intra-set levels of effort on chronic resistance training (RT) adaptations. Objective: We aimed to synthesize the current literature on chronic RT adaptations in response to different intra-set velocity loss (VL) thresholds in the back squat exercise. We investigated changes in muscle strength, muscular endurance, sports-related physical performance, and muscle hypertrophy outcomes during resistance exercise to establish optimal dose-response relationships in physically active individuals.Methods: We conducted a literature search using PubMed (Medline), Web of Science™, Scopus, and Cochrane up to April 2021, with no restriction on year of publication. The inclusion criteria were based on the PICO strategy. A random-effect meta-analysis was performed to determine the standardized mean differences (SMD ± 95% confidence intervals) for different intra-set VL thresholds (low VL [< 15%], moderate VL [≥ 15% and < 30%], and high VL [≥ 30%]) in RT on maximum muscular strength, bar velocity against submaximal loads, endurance against a given load, countermovement jump height, running sprint time, and muscle hypertrophy. Results: A total of 4,031 articles were found and 11 studies met our eligibility criteria. Pooled results revealed improvements between pre- and post-training intervention in 1RM strength (SMD = 0.78; p < 0.001); bar velocity outputs (light-loads [SMD = 0.79; p < 0.001] and heavy-loads [SMD = 2.08; p < 0.001]); endurance against a given load (SMD = 1.21; p < 0.001); countermovement jump height (SMD = 0.50; p < 0.001); running sprint time (SMD = - 0.28; p = 0.001); and muscle hypertrophy (SMD = 0.31; p = 0.05), with no significant difference between VL thresholds (p > 0.05). However, low VL elicited greater within-group SMD for 1RM strength than moderate and high VL thresholds (SMD = 0.93; 0.72; and 0.75; for low, moderate, and high VL thresholds, respectively). Low and moderate VL thresholds resulted in greater within-group SMD than high VL thresholds for velocity against light loads (SMD for low VL = 0.89; moderate VL = 0.90; high VL = 0.59); countermovement jump height (SMD for low VL = 0.51; moderate VL = 0.58; high VL = 0.36); and running sprint time (SMD for low VL = -0.49; moderate VL = -0.32; high VL = -0.09). Moderate and high VL thresholds induced higher within-group SMD for muscle hypertrophy than low VL (SMD for low VL = 0.14; moderate VL = 0.40; high VL = 0.44). Conclusions: Low to moderate VL thresholds may provide more effective and efficient training stimuli for improving performance in strength-power tasks, due to the similar or even greater chronic adaptations achieved compared with high VL, despite the lower number of repetitions performed during the RT program. Conversely, moderate to high VL may provide more favorable training stimuli for inducing muscle hypertrophy. Strength coaches may apply these dose-response trends to design optimal RT stimuli based on their specific training goals. Protocol registration: The study protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42020189321).

Sustained Sleep Restriction Reduces Resistance Exercise Quality and Quantity in Females

“…This may be supported by our finding of moderate (≥15% and <30%) intraset velocity loss in the final sets of back squats during SR compared with low (<15%) intraset velocity loss during NS. Moderate intraset velocity loss may result in nonspecific adaptations for speed and power compared with low intraset velocity loss (47). The present study cannot infer an adaptive response to resistance training with SR.…”

Perception of Barbell Velocity: Can Individuals Accurately Perceive Changes in Velocity?

“…To our knowledge, this the first investigation that has asked participants to estimate a specific velocity loss and to terminate a set based on this i.e. the participants were required to perceive a velocity loss threshold that has typically been utilized in previous VBT investigations (Banyard et al, 2017;Gantois et al, 2021). We therefore argue that this is a more practical and ecologically valid investigation when assessing the efficacy of using velocity to regulate resistance training without the assistance of velocity measuring devices.…”

“…Perception of relative changes in velocity (i.e., absolute velocity normalised to maximum velocity [% units] or change in velocity between reps [Δ% units] expressed relative to the first or fastest repetition) might be more practically relevant as prescriptive strategies such as velocity loss are easier to administer (Banyard et al, 2017;Weakley et al, 2021). Previous research has examined changes in neuromuscular performance and muscle morphology when using different percentage reductions in velocity loss, for example 20% versus 40% (Gantois et al, 2021). As different velocity loss thresholds may result in different adaptations, perception of velocity change could be of importance to practitioners and compliment estimating the velocity of a single repetition.…”

Toward a New Paradigm in Resistance Training by Means of Velocity Monitoring: A Critical and Challenging Narrative

“…However, power output will necessarily be improved against a given absolute load if the applied force increases, regardless of the part of the curve in which the effect occurs. Furthermore, assuming that the effect of training on power is measured by means of actions such as jumps, throws, or movements against light loads, a further performance improvement is likely to occur when RT is performed using low to moderate loads, a low number of repetitions per set and fast lifting velocities (i.e., low degree of fatigue) compared to highly fatiguing training protocols [23,24,32,33,35,46,48,67,114,115]. Consequently, the suggestion or recommendation that it is necessary to previously perform the phases of "muscular endurance, " "hypertrophy" and "maximum strength" to improve power does not seem justified.…”