We compared the effects of two resistance training (RT) programs only differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40) on muscle structural and functional adaptations. Twenty‐two young males were randomly assigned to a VL20 (n = 12) or VL40 (n = 10) group. Subjects followed an 8‐week velocity‐based RT program using the squat exercise while monitoring repetition velocity. Pre‐ and post‐training assessments included: magnetic resonance imaging, vastus lateralis biopsies for muscle cross‐sectional area (CSA) and fiber type analyses, one‐repetition maximum strength and full load‐velocity squat profile, countermovement jump (CMJ), and 20‐m sprint running. VL20 resulted in similar squat strength gains than VL40 and greater improvements in CMJ (9.5% vs 3.5%, P < 0.05), despite VL20 performing 40% fewer repetitions. Although both groups increased mean fiber CSA and whole quadriceps muscle volume, VL40 training elicited a greater hypertrophy of vastus lateralis and intermedius than VL20. Training resulted in a reduction of myosin heavy chain IIX percentage in VL40, whereas it was preserved in VL20. In conclusion, the progressive accumulation of muscle fatigue as indicated by a more pronounced repetition velocity loss appears as an important variable in the configuration of the resistance exercise stimulus as it influences functional and structural neuromuscular adaptations.

This study aimed to compare the effect on neuromuscular performance of 2 isoinertial resistance training programs that differed only in actual repetition velocity: maximal intended (MaxV) vs. half-maximal (HalfV) concentric velocity. 21 resistance-trained young men were randomly assigned to a MaxV (n=10) or HalfV (n=11) group and trained for 6 weeks using the full squat exercise. A complementary study (n=8) described the acute metabolic and mechanical response to the protocols used. MaxV training resulted in a likely more beneficial effect than HalfV on squat performance: maximum strength (ES: 0.94 vs. 0.54), velocity developed against all (ES: 1.76 vs. 0.88), light (ES: 1.76 vs. 0.75) and heavy (ES: 2.03 vs. 1.64) loads common to pre- and post-tests, and CMJ height (ES: 0.63 vs. 0.15). The effect on 20-m sprint was unclear, however. Both groups attained the greatest improvements in squat performance at their training velocities. Movement velocity seemed to be of greater importance than time under tension for inducing strength adaptations. Slightly higher metabolic stress (blood lactate and ammonia) and CMJ height loss were found for MaxV vs. HalfV, while metabolite levels were low to moderate for both conditions. MaxV may provide a superior stimulus for inducing adaptations directed towards improving athletic performance.

The purpose of this study was to compare the effect on strength gains of two isoinertial resistance training (RT) programmes that only differed in actual concentric velocity: maximal (MaxV) vs. half‐maximal (HalfV) velocity. Twenty participants were assigned to a MaxV (n = 9) or HalfV (n = 11) group and trained 3 times per week during 6 weeks using the bench press (BP). Repetition velocity was controlled using a linear velocity transducer. A complementary study (n = 10) aimed to analyse whether the acute metabolic (blood lactate and ammonia) and mechanical response (velocity loss) was different between the MaxV and HalfV protocols used. Both groups improved strength performance from pre‐ to post‐training, but MaxV resulted in significantly greater gains than HalfV in all variables analysed: one‐repetition maximum (1RM) strength (18.2 vs. 9.7%), velocity developed against all (20.8 vs. 10.0%), light (11.5 vs. 4.5%) and heavy (36.2 vs. 17.3%) loads common to pre‐ and post‐tests. Light and heavy loads were identified with those moved faster or slower than 0.80 m·s⁻¹ (∼60% 1RM in BP). Lactate tended to be significantly higher for MaxV vs. HalfV, with no differences observed for ammonia which was within resting values. Both groups obtained the greatest improvements at the training velocities (≤0.80 m·s⁻¹). Movement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect. BP strength gains can be maximised when repetitions are performed at maximal intended velocity.

Purpose: To analyze the effects of 2 resistance-training (RT) programs that used the same relative loading but different repetition volume, using the velocity loss during the set as the independent variable: 15% (VL15) vs 30% (VL30).Methods: Sixteen professional soccer players with RT experience (age 23.8 ± 3.5 y, body mass 75.5 ± 8.6 kg) were randomly assigned to 2 groups, VL15 (n = 8) or VL30 (n = 8), that followed a 6-wk (18-session) velocity-based squat-training program. Repetition velocity was monitored in all sessions. Assessments performed before (Pre) and after training (Post) included estimated 1-repetition maximum (1RM) and change in average mean propulsive velocity (AMPV) against absolute loads common to Pre and Post tests, countermovement jump (CMJ), 30-m sprint (T30), and Yo-Yo Intermittent Recovery Test (YIRT). Null-hypothesis significance testing and magnitude-based-inference statistical analyses were performed.Results: VL15 obtained greater gains in CMJ height than VL30 (P < .05), with no significant differences between groups for the remaining variables. VL15 showed a likely/possibly positive effect on 1RM (91/9/0%), AMPV (73/25/2%), and CMJ (87/12/1%), whereas VL30 showed possibly/unclear positive effects on 1RM (65/33/2%) and AMPV (46/36/18%) and possibly negative effects on CMJ (4/38/57%). The effects on T30 performance were unclear/unlikely for both groups, whereas both groups showed most likely/likely positive effects on YIRT.Conclusions: A velocity-based RT program characterized by a low degree of fatigue (15% velocity loss in each set) is effective to induce improvements in neuromuscular performance in professional soccer players with previous RT experience.

Purpose: This study aimed to compare the effects of four resistance training (RT) programs with different velocity loss (VL) thresholds: 0% (VL0), 10% (VL10), 20% (VL20), and 40% (VL40) on sprint and jump performance, muscle strength, neuromuscular, muscle hypertrophy, and architectural adaptations. Methods: Sixty-four young resistance-trained men were randomly assigned into four groups (VL0, VL10, VL20, and VL40) that differed in the VL allowed in each set. Subjects followed an RT program for 8 wk (two sessions per week) using the full-squat (SQ) exercise, with similar relative intensity (70%–85% 1-repetition maximum), number of sets (3), and interset recovery period (4 min). Before and after the RT program, the following tests were performed: 1) muscle hypertrophy and architecture of the vastus lateralis (V_LA), 2) tensiomyography, 3) 20-m running sprint, 4) vertical jump, 5) maximal voluntary isometric contraction in SQ, 6) progressive loading test in SQ, and 7) fatigue test. Results: No between-group differences existed for RT-induced gains in sprint, jump, and strength performance despite the differences in the total volume performed by each group. VL20 and VL40 showed significant increases (P < 0.001) in muscle hypertrophy (group–time interaction, P = 0.06). However, only VL40 exhibited a significant slowing (P < 0.001) of the delay time in the V_LA muscle (group–time interaction, P = 0.05). Moreover, VL40 showed a significant decrease in the early rate of force development (P = 0.04). Conclusions: Higher VL thresholds (i.e., VL20 and VL40) maximized hypertrophic adaptations, although an excessive VL during the set (i.e., VL40) may also induce negative neuromuscular adaptations. Therefore, moderate VL thresholds should be chosen to maximize strength adaptations and to prevent negative neuromuscular adaptations.