Shuttle-Run Interval Training with More Directional Changes Induces Superior Gains in Shuttle Sprint Performance in Female Professional Futsal Players

Purpose
To compare the chronic (5-week) effects of two shuttle run interval training modes with one (shuttle running interval training 1, SRIT-1) and three (SRIT-3) directional changes on blood lactate responses ([La]), strength, power, and speed capacities of female futsal players.

Methods
Fourteen players performed unloaded squat (SJ) and countermovement (CMJ) jumps. Isokinetic assessments of lower limbs and a single 40-m shuttle-sprint test took place before and after the training program. [La] was measured after each running set during the 1st and 10th training session.

Results
[La] values were very likely reduced in the 10th compared with the 1st session in both groups. After SRIT-3, very likely moderate improvements occurred in the 40-m shuttle-sprint speed test (Δ = +2.9%; 90% CI: 1.7–4.1), while changes were unclear following SRIT-1 (1.0%; from –1.0 to 3.1). Changes in SJ (SRIT-1: +7.8%; 0.8–15.3; SRIT-3: +9.2%; 4.4–14.2) and CMJ height (SRIT-1: +7.0%; 1.1–13.1; SRIT-3: +8.4%; 3.7–13.3) were likely to very likely beneficial following both training protocols. Knee extensor concentric peak torque was likely and very likely increased in the post-training period for both SRIT-1 (+18.3%; 1.9–37.4) and SRIT-3 (+17.3%; 4.6–31.6), respectively. Knee extensor eccentric peak torque was very likely improved after SRIT-3 (+9.5%; 4.7–14.4), but unclear following SRIT-1 (+3.4%; from –6.3 to 14.1). Following SRIT-3, changes in the 40-m shuttle-sprint speed were likely (+1.8%; from –0.4 to 4.1) superior to those observed in SRIT-1.

Conclusions
SRIT-3, probably because of the higher number of horizontal accelerations, might be more effective than SRIT-1 (with fewer changes of direction) to induce greater adaptations in 40-m shuttle sprint in female futsal players.