Movement tempo is a key but often overlooked resistance-training variable that alters time under tension (TUT) and can influence neural and morphological adaptations. Eccentric contraction characteristics are of particular interest because eccentric actions can produce greater force than concentric ones and may enhance protein synthesis and anabolic signaling. Prior studies offer mixed findings on optimal tempos for maximal strength versus explosive power, possibly due to heterogeneous participant training status, non-functional single-joint exercises, or insufficient isolation of contraction-phase tempos. This study focused on isolating eccentric contraction tempo during a functional multi-joint exercise (back squat) while keeping concentric phases explosive (X) to clarify tempo-specific effects on lower-limb strength and explosive performance.
The primary aim was to investigate how 8 weeks of squat training with different eccentric tempos (4/0/X/0, 2/0/X/0, and self-selected V/V/X/V) affects maximal back-squat strength, countermovement jump (CMJ) height, squat jump (SJ) height, and 30-meter sprint performance in university students majoring in sports training.
This was a randomized controlled trial with pre- and post-intervention testing. An a priori power analysis (F-test for repeated-measures ANOVA, f = 0.3, α = 0.05, power = 0.8, 3 groups, 2 measurements) determined a required total sample size of 30. Participants were randomly allocated to one of three tempo groups by a researcher blinded to baseline measures. Training was performed twice weekly for 8 weeks.
Thirty university students majoring in sports training were enrolled and randomly assigned to the 2/0/X/0, 4/0/X/0, or V/V/X/V groups. Allocation was performed by a blinded researcher. The manuscript reports that raw data are available as supplementary materials. No additional participant demographic details (age, sex distribution, prior training status) were reported in the provided source excerpt.
Three tempo conditions were used:
All groups performed loaded back-squat training twice per week for 8 weeks with tempo instruction according to group assignment. The concentric phase for tempo-controlled groups was performed at maximal intended velocity (X) to prioritize concentric explosiveness. The study design emphasized isolating eccentric-tempo effects by holding concentric intent constant.
Primary and secondary performance measures were assessed before and after the 8-week intervention. These included:
A two-way repeated-measures ANOVA was used to evaluate training outcomes across time and between groups. Effect size (ES) analyses were reported descriptively to indicate the magnitude of within-group changes. Significance thresholds reported in the abstract used conventional P < 0.05 and P < 0.01 levels.
Maximal squat strength
Countermovement jump (CMJ) and squat jump (SJ)
30-meter sprint
Overall pattern
The results suggest that eccentric tempo modification has differential effects on strength versus explosive outcomes. A 2-second eccentric phase combined with explosive concentric intent provided the most balanced improvements in maximal strength and explosive performance in this cohort of sports-training students. By contrast, a slower 4-second eccentric phase produced strength gains but impaired jump and sprint abilities, possibly due to altered neuromuscular coordination or reduced specificity for stretch-shortening cycle actions. The self-selected tempo group achieved moderate strength gains and small improvements in explosive measures, reflecting common-practice training outcomes where athletes choose comfortable tempos.
These findings align with prior literature proposing that shorter eccentric durations (under ~2 seconds) may better preserve or enhance subsequent concentric and stretch-shortening cycle performance, whereas prolonged eccentric durations may favor hypertrophy or maximal isometric capacity but reduce dynamic explosive outcomes. The authors emphasized the need to isolate contraction-phase tempos in multi-joint, sport-relevant movements to interpret tempo-specific adaptations.
In this randomized trial of university sports students, 8 weeks of squat training with a 2/0/X/0 eccentric tempo elicited the most favorable combined improvements in maximal squat strength and explosive power (CMJ, SJ, sprint) compared with 4/0/X/0 and self-selected tempos. The 4/0/X/0 tempo increased maximal strength but coincided with decreases in stretch-shortening cycle–dependent explosive performance.