Volgens deze studie worden beginnende atleten sterkers als ze op rustdagen stretchen.

ehhh...., het is maar hoe je het wilt lezen... Wreckless. 
Volgens hetzelfde artikel moet je er geen hoge verwachtingen van hebben.
Het effect valt dus tegen!

Andere studies over stretchen laten zien dat ze ook geen noemenswaardige preventie bieden tegen blessures,
krachtopbouw, hypertrofie.

Dat je door stretchen je fascia zou kunnen oprekken (andere studies die groei pretenderen door stretchen) waardoor de spier ruimer in z'n kapsel komt en meer ruimte heeft om te groeien, blijken ook schromelijk overdreven. De effecten zijn nihil tot extreem minimaal, zeg maar verwaarloosbaar.

De loftrompet kan dus weer de koffer in.

Dit is de abstract van het onderzoek:
This study investigated differences in lower-body strength improvements when using standard progressive resistance training (WT) vs. the same progressive resistance training combined with static stretching exercises (WT + ST). T
hirty-two college students (16 women and 16 men) were pair matched according to sex and knee extension 1 repetition maximum (1RM). One person from each pair was randomly assigned to WT and the other to WT + ST. WT did 3 sets of 6 repetitions of knee extension, knee flexion, and leg press 3 days per week for 8 weeks with weekly increases in the weight lifted. The WT + ST group performed the same lifting program as the WT group along with static stretching exercises designed to stretch the hip, thigh, and calf muscle groups. Stretching exercise sessions were done twice a week for 30 minutes during the 8-week period.
WT significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 12, 14, and 9%, respectively.
WT + ST, on the other hand, significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 16, 27, and 31, respectively.
In addition, the WT + ST group had significantly greater knee extension and leg press gains (p < 0.05) than the WT group. Based on results of this study, it is recommended that to maximize strength gains in the early phase of training, novice lifters should include static stretching exercises to their resistance training programs.