Not sure the title is misleading (but appreciate your bluntness), if one interprets less volume...

While I try to get the paper again, I am curious about your thoughts on perhaps a better paper, albeit a meta-analysis, as you are more knowledgeable about the fitness realm:

https://www.frontiersin.org/articles/10.3389/fspor.2022.873718/full

Michael

Here is the abstract's method section (granted, not with the full spectrum of details you seek, such as velocity - Were the eccentrics slower? Newbies/novices? Etc.). And obviously short-term follow-up.

Abstract

Purpose

This study compared concentric–eccentric coupled (CON-ECC), concentric-only (CON), and eccentric-only (ECC) resistance training of the elbow flexors for their effects on muscle strength and hypertrophy.

Methods

Non-resistance-trained young adults were assigned to one of the four groups: CON-ECC (n = 14), CON (n = 14) and ECC (n = 14) training groups, and a control group (n = 11) that had measurements only. The training group participants performed dominant arm elbow flexor resistance training in extended elbow joint angles (0°–50°) twice a week for 5 weeks. The total training volume (dumbbell weight × number of contractions) in CON-ECC (5745 ± 1020 kg) was double of that in CON (2930 ± 859 kg) and ECC (3035 ± 844 kg), because 3 sets of 10 contractions were performed for both directions in CON-ECC. Maximum voluntary isometric (MVC-ISO), concentric (MVC-CON), and eccentric contraction (MVC-ECC) torque of the elbow flexors and biceps brachii and brachialis muscle thickness (MT) were measured at baseline, and 3–9 days post-last training session.

Results

No significant changes in any measures were evident for the control group. The CON-ECC and ECC groups showed increases (P < 0.05) in MVC-ISO (12.0 ± 15.7% and 11.3 ± 10.8%, respectively) and MVC-ECC torque (12.5 ± 18.3%, 16.2 ± 11.0%) similarly. Increases in MVC-CON torque (P < 0.05) were evident for the CON-ECC (17.5 ± 13.5%), CON (10.5 ± 12.8%), and ECC (14.2 ± 10.4%) groups without a significant difference among groups. MT increased (P < 0.01) after CON-ECC (10.6 ± 5.4%) and ECC (9.7 ± 7.2%) similarly, but not significantly after CON (2.5 ± 4.8%).

Conclusions

ECC training increased muscle strength and thickness similarly to CON-ECC training, despite the half training volume, suggesting that concentric contractions contributed little to the training effects.