ECSS Paris 2023: OP-PN27
INTRODUCTION: Blood flow restriction (BFR) during high-intensity interval exercise (HIIE) may induce high physiological stress, but this could occur at the cost of training intensity. This study compared the acute physiological and perceptual responses to three BFR methods applied during HIIE. METHODS: Twenty-four healthy males (age 25 ± 3.5 years, maximal aerobic power (MAP) 264 ± 61 W) completed four experimental trials in a randomised order. All HIIE consisted of 3 sets of 5 × 30-s on, 30-s off cycling intervals interspersed with 3-min of passive rest. The exercise intensities and BFR applied were: (i) control (CON) – 100% MAP, no BFR; (ii) rest occlusion (RO) – 100% MAP, 80% limb occlusion pressure (LOP) for 2-min during passive rest between sets; (iii) exercise low occlusion (ELO) – 70% MAP, 50% LOP during exercise; and (iv) exercise high occlusion (EHO) – 70% MAP, 80% LOP during exercise. Heart rate (HR), blood lactate (bLa), rating of perceived pain and discomfort (RPD) and rating of perceived exertion (RPE) were measured after warm-up and each exercise set. Surface electromyography was measured on the vastus lateralis (VL) and biceps femoris (BF) on the 1st and 5th repetition of each exercise set, followed by root mean square (RMS) analysis. Repeated measures ANOVA compared measures across conditions and time points, followed by post-hoc t-tests with Bonferroni adjustments where appropriate. Significance was set at p < 0.05. RESULTS: Two participants withdrew from EHO due to intolerable pain. The RPE and RPD during exercise were: (mean ± SD) CON = 11.9 ± 2.8 and 1.1 ± 1.4; RO = 12.1 ± 2.8 and 1.7 + 1.7; ELO = 11.7 ± 2.4 and 1.9 ± 1.7; EHO = 13.0 ± 3.1 and 3.4 ± 2.6). Main effects of condition, time and condition × time interactions were observed for RPE and RPD (all p < 0.05) with post-hoc t-tests showing a greater increase in both RPE and RPD across sets in EHO than the other conditions. Similarly, main effects of condition, time and condition × time interactions were observed for both HR and bLa (all p < 0.05) which were significantly lower in ELO than all other conditions (mean HR (bpm) and bLa (mmol∙l-1): CON = 137 ± 27 and 6.8 ± 3.0; RO = 141 ± 26 and 7.1 ± 3.1; ELO = 133 ± 26 and 5.3 ± 1.9; EHO = 139 ± 28 and 6.8 ± 3.0, all p < 0.05). HR was significantly higher in RO vs CON from exercise set 2 onwards (all p < 0.05) whereas bLa was greater in RO than CON 5-min post-exercise. Main effects of condition and time (all p < 0.05) were observed for RMS-VL and RMS-BF, with post-hoc tests indicating significantly higher RMS on CON and RO than ELO and EHO. For RMS-VL, there was a condition × time interaction, with significantly higher RMS observed during the last repetition in RO than CON (142 ± 18.0 vs 132 ± 14.9 mV, p < 0.05). CONCLUSION: Applying BFR during rest between HIIE sets (RO) elicits high physiological stresses – perceived pain, heart rate and blood lactate – without compromising muscle activation or exercise intensity.
Read CV Man Tong ChuaECSS Paris 2023: OP-PN27
INTRODUCTION: Blood flow restriction (BFR) training can increase rates of muscular adaptations at equal, and lower training intensities than traditional strength training. BFR induces hypoxia in the working muscle inducing greater fatigue, promoting angiogenesis as well morphological responses. There is currently limited knowledge as to the effects of blood flow restricted recovery on morphological and neuromuscular adaptations. Therefore, the aim of this study was to investigate whether blood flow restricted recovery can elicit strength and neuromuscular adaptations over a 4-week isokinetic strength training program. METHODS: Following local institutional ethical approval 20 physically active participants (n = 12 male, n = 8 female) volunteered to participate (mean ± SD: age = 21.0 ± 2.3 years, height = 174.5 ± 9.2 cm, mass = 75.2 ± 14.0 kg. A single-blinded repeated measures matched pairs design was implemented with 3 training conditions: 20 mmHg [SHAM], 40% limb occlusion pressure (40-LOP), and 80% LOP (80-LOP). Participants completed baseline and post testing ankle-brachial index (ABI), 60 cm Drop Jumps, 6 s and isokinetic concentric knee flexion-extension at 60 and 180 °.s-1. During dynamometer testing electromyography (100 Hz) and Near Infrared Spectroscopy (10Hz) were recorded at the mid-point of rectus femoris. Isokinetic training consisted of 12 sessions, 3 times per week for 4 weeks at 60 °.s-1 with blood flow restricted recovery. For sessions 1-6 participants completed 3 sets of 5 repetitions per leg with 120 s recovery between sets; sessions 7-9: 3 sets of 5 repetitions per leg with 90 s recovery between sets; and sessions 10-12: 2 of 5 repetitions with 120 s recovery, and 2 sets with 180 s unrestricted recovery. RESULTS: A significant pre to post increase (P = 0.004) in peak torque (60°.s-1) was observed in LOP-40 (Pre: 147 ± 51 Nm, Post: 208 ± 79 Nm) ES= 0.97 ±95% CI -33.1 – 31.2. There was a significant increase in peak torque for LOP-80 (60°.s-1) from 178 ± 36 to 216 ± 33 Nm (P= 0.02), ES= 1.17 ±95% CI -17.0 – 14.7. Significant decreases in tissue oxygenation mean response time (MRT) were observed for LOP-40 (P= 0.01) from 31.2 ± 3.9 s to 23.8 ± 5.7 s, ES= 1.63 ±95% CI -0.7 – 4.0 and LOP-80 (P= 0.01) 38.4 ± 8.6 s to 25.6 ± 8.9 s ES= 1.56 ±95% CI -2.44 – 5.57. Average iEMG increased at 60 °.s-1 from 2892.3 ± 692.6 mV to 3472.6 ± 852.2 mV (P= 0.01) ES=0.80 ±95% CI -377.5 – 375.8. Non-significant changes observed for peak torque, iEMG or MRT at 180 °.s-1. Additionally there was no change across any group for drop jump performance (P> 0.05). CONCLUSION: Blood flow restricted recovery promoted significant gains in both peak torque and MRT. Suggesting, that it proffers a modality that allows for maximal force generation during the exercise whilst enhancing the adaptive process by facilitating a hypoxic environment during recovery. Attention now needs be given to establishing optimal LOP and the mechanisms of these adaptations.
Read CV Dan GordonECSS Paris 2023: OP-PN27
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.
Read CV Ching Feei ChenECSS Paris 2023: OP-PN27