| Summary: | Introduction: In recent years the velocity-based resistance training (VBRT) approach has gained
popularity in sports coaching and scientific research. VBRT is classified as resistance training in which
movement velocity is used as a depended variable in quantifying the training load (intensity, volume,
e.g.). An important application of VBRT is quantifying the optimal number of repetitions per set to target
to specific training adaptations by using the velocity loss within the set as a determinant. The purpose of
this study was to compare neuromuscular effects of two different, 20 and 40 %, within set velocity loss
resistance programs (VL20 and VL40) in lower and upper body in young men and women.
Methods: The study included a one-week control period and thereafter an 8-week training intervention
consisting 15 training sessions. Measurements were made in four testing sessions: Control, Pre, Mid and
Post. 24 healthy young men (aged 26.4 ± 3.9 years) and 25 women (aged 25.5 ± 3.8 years) were assigned
to 4 different groups: VL20M = 20 % velocity loss men (n=12), VL40M = 40 % velocity loss men (n=12),
VL20W = 20 % velocity loss women (n=13) and VL40W = 40 % velocity loss women (n=12). The
training program consisted two exercises: Smith machine full back squat (BS) and Smith machine bench
press (BP). During the training program, all the repetitions were performed with the maximal initial
velocity in every training session and the training intensity and the number of repetitions per each set were
determined by using the velocity-based approach. Both VL20 groups continued performing their exercise
sets until they reached the within-set mean propulsive velocity (MPV) loss of 20 % and both VL40 until
the MPV loss of 40 %. The following neuromuscular measurements were performed: 1RMs in BS and
BP, mean MPVs against high and low submaximal loads in BS and BP, countermovement jump (CMJ),
squat jump (SJ), maximal isometric leg press force (ILP Fmax), maximal isometric bench press force (IBP
Fmax), rate of force development (RFD) in ILP, average force during 0-100 ms (F100ms) in ILP, integrated
electromyography (IEMG) during 500-1500 ms in ILP and during the concentric phase in CMJ as well as
vastus lateralis (VL) cross-sectional area (CSA).
Results: Significant (p<0.05) increases in BS and BP 1RMs (mean 7–10 %) were observed in both groups
in men. VL20M and VL40M also showed significant increases (p<0.05) in VL CSA at Post (mean 15–20
%), and in BS and BP MPV against high and low loads at Post (mean 0.04–0.17 m/s), except in VL40M
BP MPV against low loads the change was not significant. No significant between group differences were
observed between VL20M and VL40M in any of the variables at any measurement point. Significantly
higher (p<0.05) increases were observed from Pre to Post in BS MPV against low loads (0.19 vs 0.14
m/s) and BP MPV against high loads (0.14 vs 0.09 m/s) in VL40W than in VL20W. In turn, significantly
(p<0.05) higher increases from Pre to Post were observed in RFD (32.4 vs 0.7 %) in ILP and VL+VM
IEMG during CMJ (38.5 vs 12.4 %) in VL20W than in VL40W.
Conclusions: Similar adaptations took place in men to both training programs. Women increased their
dynamic performance more using VL40 training than VL20 training. Whereas, in explosive isometric
performance and muscle activation the VL20 training program led to higher gains in women. The different
neuromuscular responses to VL20 and VL40 training between sexes in the present study indicate that
velocity-based training programs should be designed differently for men and women.
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