PURPOSE: Limited research exists examining muscle architectural changes in conjunction with performance measures throughout an athlete’s competitive season. The purpose was to examine changes in muscle architecture and explosive ability in DI collegiate volleyball players throughout a competitive season.
METHODS: Ten female volleyball players (20.4 ± 1.1 y, 178.3 ± 4.8 cm, 72.6 ± 5.3 kg) were recruited for the study. Athletes were tested at pre-season (T1), pre-taper (T2), and post-taper (T3) on measures of vastus lateralis muscle thickness (MT), pennation angle (PA), and fascicle length (FL) using ultrasonography, countermovement jump height (JH), time to takeoff from initiation of the unweighting phase (TTT), and peak power allometrically scaled (PPa) measured using a force platform. Training load (TL: session RPE·duration) and strength training volume-load times displacement (VLd) were monitored for 15 wks. One-way repeated measures ANOVAs with post-hoc comparisons were used for analysis with alpha level set at p≤0.05.
RESULTS: There was a reduction in VLd/wk (1886 ± 422 to 571 ±130 kg/wk, p<0.001, d=3.1) and TL/wk (3140 ± 561 to 1656 ± 409 a.u., p<0.001, d=2.7) between in-season (T1-T2) and tapering (T2-T3) training phases. There were time effects for MT (p<0.001) and PA (p=0.03). Post-hoc comparisons revealed changes in MT (T1-T2: 2.1 ± 0.3 to 2.96 ± 0.54 cm, p<0.001, d=2.8; T1-T3: 2.1 ± 0.3 to 2.63 ± 0.36 cm, p<0.001, d=1.7; and T2-T3: 2.96 ± 0.54 to 2.63 ± 0.36 cm, p=0.01, d=0.6), PA (T1-T2: 12.59 ± 0.81 to 15.76 ± 3.38°, p=0.02, d=3.9), and no statistical changes in FL, JH, or PPa. Despite the absence of a time effect, a decreasing trend was observed in TTT from T1-T3: 798 ± 98 to 767 ± 106 ms, p=0.04, d=0.32, and T2-T3: 789 ± 101 to 767 ± 106 ms, p=0.04, d=0.22.
CONCLUSION: In-season training resulted in favorable changes in muscle architecture, which remained elevated above pre-season values following the taper. These muscle architectural changes did not appear to appreciably alter explosive ability throughout the competitive season. However, the reductions in TL and VLd during the taper might have improved stretch-shortening cycle efficiency as evidenced by the reductions in TTT. Collegiate volleyball athletes may benefit from a taper where both TL and VLd are substantially reduced prior to important competitions.