Author(s): CHEN, C.F., HSIN, F.Y., CHEN, Y.J., CHEN, H.H., FANG, C.C., CHAN, K.H., Institution: NATIONAL TAIWAN SPORT UNIVERSITY, Country: TAIWAN, Abstract-ID: 423

INTRODUCTION:
Plyometric exercises (PLY) have been used as conditioning activity to enhance subsequent performance by eliciting postactivation potentiation (PAP). Studies indicated that exercises combined with blood flow restriction (BFR) may strengthen the PAP response. Besides, exercises combined with BFR could also increase muscle thickness and blood levels of anabolic hormones, which may contribute to enhance performance. Therefore, the aim of this study was to examine the acute effects of PLY with BFR on muscle thickness of rectus femoris (RF) and vastus lateralis (VL) as well as changes in blood levels of total testosterone (total-T), free testosterone (free-T) and sex hormone-binding globulin (SHBG). We hypothesized that PLY with BFR would increase muscle thickness or blood anabolic hormones levels of female players.
METHODS:
Eleven female basketball and volleyball players (19.45 ± 0.93 yrs, 168.77 ± 5.98 cm, and 62.91 ± 9.57 kg) were recruited into the study. A crossover and counterbalanced manner was used to investigate the muscle thickness and blood levels of anabolic hormones after single bouts of PLY and PLY with BFR (PLY-BFR). Subjects conducted the 2 trials in same menstrual cycle phase. PLY consisted of 40 drops of ankle hops, hurdle hops and drop jumps. In PLY-BFR, subjects conducted PLY, and cuff pressure of 80% arterial occlusion pressure was applied to subjects’ quadriceps of dominant leg. The venous blood samples were drawn before and 15 min after warm-up exercises to analysis the blood levels of total-T, free-T and SHBG. Muscle thickness of RF and VL were measured before, immediately and 15 min after exercises. A two-way ANOVA with repeated measures was used to compare differences within trials and time points. Statistical significance was set at α = .05. All data are expressed as mean ± SD.
RESULTS:
No significant differences were found in muscle thickness of RF (PLY: 2.22 ± 0.37 and 2.16 ± 0.34 vs. 2.14 ± 0.27 cm, p > .05; PLY-BFR: 2.22 ± 0.35 and 2.21± 0.38 vs. 2.14 ± 0.37 cm, p > .05) or VL (PLY: 2.22 ± 0.37 and 2.16 ± 0.34 vs. 2.14 ± 0.27 cm, p > .05; PLY-BFR: 2.22 ± 0.35 and 2.21± 0.38 vs. 2.14 ± 0.37 cm, p > .05) within time points or trials. Furthermore, there were no significant changes in blood levels of total-T (PLY: 0.57 ± 0.20 vs. 0.58 ± 0.19 ng/mL, p > .05; PLY-BFR: 0.58 ± 0.19 vs. 0.56 ± 0.19 ng/mL, p > .05) , free-T (PLY: 8.24 ± 5.40 vs. 6.46 ± 2.75 pg/mL, p > .05; PLY-BFR: 6.37 ± 2.21 vs. 6.55 ± 2.27 pg/mL, p > .05), or SHBG (PLY: 70.85 ± 25.47 vs. 68.82 ± 22.48 nmol/L, p > .05; PLY-BFR: 68.84 ± 18.14 vs. 64.63 ± 14.18 nmol/L, p > .05) after 15 min of exercises within trials.
CONCLUSION:
The results of present study indicate that a single bout of plyometric exercises with blood flow restriction could not increase either muscle thickness or blood levels of anabolic hormones of female players. More studies are needed to investigate whether it is a practical warm-up strategy to improve performance of players.