). 1 Recent research reported greater changes in blood volume/perfusion in both conditions of BFR 4 and systemic hypoxia compared with normoxia during acute high-intensity leg-cycling repeated-sprint exercise. 5 Similar responses of greater changes in blood perfusion have also been observed after
Sarah J. Willis, Grégoire P. Millet and Fabio Borrani
Gordon Sleivert, Val Burke, Craig Palmer, Alan Walmsley, David Gerrard, Stephen Haines and Roger Littlejohn
To determine the effects of deer antler velvet on maximal aerobic performance and the trainability of muscular strength and endurance, 38 active males were randomly assigned in a double-blind fashion to either deer antler velvet extract (n = 12), powder (n = 13), or placebo groups (n = 13). Subjects were tested prior to beginning supplementation and a 10-week strength program, and immediately post-training. All subjects were measured for circulating levels of testosterone, insulin-like growth factor, erythropoietin, red cell mass, plasma volume, and total blood volume. Additionally, muscular strength, endurance, and VO2max were determined. All groups improved 6 RM strength equivalently (41 ± 26%, p < .001), but there was a greater increase in isokinetic knee extensor strength (30 ± 21% vs. 13 ± 15%, p = .04) and endurance (21 ± 19% vs. 7 ± 12%, p = .02) in the powder compared to placebo group. There were no endocrine, red cell mass or VO2max changes in any group. These findings do not support an erythropoetic or aerobic ergogenic effect of deer antler velvet. Further, the inconsistent findings regarding the effects of deer antler velvet powder supplementation on the development of strength suggests that further work is required to test the robustness of the observation that this supplement enhances the strength training response and to ensure this observation is not a type I error.
Philippe Richard and François Billaut
used to calculate micromolar changes in tissue oxyhemoglobin–oxymyoglobin ([O 2 HbMb]), deoxyhemoglobin–deoxymyoglobin ([HHbMb]), and total hemoglobin–myoglobin ([THbMb] = [O 2 HbMb] + [HHbMb])—an index of change in regional blood volume. 23 The equilibrium between oxygen supply and consumption was
Michael D. Nelson, Lynneth A. Stuart-Hill and Gordon G. Sleivert
To evaluate the influence of acute hypervolemia, achieved through the ingestion of a sodium citrate-rich beverage, on cardiovascular strain and thermoregulatory function, during moderate-intensity aerobic exercise in a warm environment. Sodium citrate’s ability to increase buffering capacity was also assessed.
Twelve endurance-trained athletes completed two blind randomized treatment trials, separated by a minimum of seven days, on a cycle ergometer under heat stress (30.9°C, 64% RH). The subjects ingested 12 mL·kg−1of (1) Gatorade, the control (CNT), or (2) sodium-citrate plus Gatorade (NaCIT: 170 mmol Na+L−1) before cycling at 15% below ventilatory threshold (VT) for 62 minutes. Core and skin temperature, expired gas samples, heart rate, and perceived exertion were measured throughout exercise. Blood samples were taken before drinking each beverage, before commencing exercise, and throughout the exercise bout.
Plasma volume (PV) was significantly expanded in the NaCIT trial (3.6 ± 5.5%) and remained significantly higher throughout exercise in the NaCIT trial compared with the CNT trial (P ≤ .05). No significant differences were found in heart rate, in core and skin temperature, or in the metabolic data between the treatment groups. NaCIT significantly increased [HCO3 −], base excess, and pH throughout the trial.
Acute oral ingestion of high-sodium citrate beverages before moderate exercise induces mild levels of hypervolemia and improves blood-buffering capacity in humans; however, mild hypervolemia during 62 minutes of moderate exercise does not reduce physiological strain or improve thermoregulation.
Blake D. McLean, Kevin White, Christopher J. Gore and Justin Kemp
1 —Timeline of blood volume measurements over years 1–3 . The primary training location in every year was Melbourne, Australia, with the following addition of off-site training camps: Year 1 —21-day “altitude” camp, Flagstaff, AZ Year 2 —19-day “altitude” camp, Park City, UT Year 3— 6-day “heat
Dennis-Peter Born, Christoph Zinner, Britta Herlitz, Katharina Richter, Hans-Christer Holmberg and Billy Sperlich
The current investigation assessed tissue oxygenation and local blood volume in both vastus lateralis muscles during 3000-m race simulations in elite speed skaters on ice and the effects of leg compression on physiological, perceptual, and performance measures.
Ten (6 female) elite ice speed skaters completed 2 on-ice trials with and without leg compression. Tissue oxygenation and local blood volume in both vastus lateralis muscles were assessed with near-infrared spectroscopy. Continuous measures of oxygen uptake, ventilation, heart rate, and velocity were conducted throughout the race simulations, as well as blood lactate concentration and ratings of perceived exertion before and after the trials. In addition, lap times were assessed.
The investigation of tissue oxygenation in both vastus lateralis muscles revealed an asymmetry (P < .00; effect size = 1.81) throughout the 3000-m race simulation. The application of leg compression did not affect oxygenation asymmetry (smallest P = .99; largest effect size = 0.31) or local blood volume (P = .33; 0.95). Lap times (P = .88; 0.43), velocity (P = .24; 0.84), oxygen uptake (P = .79; 0.10), ventilation (P = .11; 0.59), heart rate (P = .21; 0.89), blood lactate concentration (P = .82; 0.59), and ratings of perceived exertion (P = .19; 1.01) were also unaffected by the different types of clothing.
Elite ice speed skaters show an asymmetry in tissue oxygenation of both vastus lateralis muscles during 3000-m events remaining during the long gliding phases along the straight sections of the track. Based on the data, the authors conclude that there are no performance-enhancing benefits from wearing leg compression under a normal racing suit.
Daniel J. Plews, Ben Scott, Marco Altini, Matt Wood, Andrew E. Kilding and Paul B. Laursen
detection of the amount of light that is reflected by a photodetector or a camera located next to the light source. The resulting PPG signal is composed of a direct current (DC) component, which varies slowly depending on tissue properties and blood volume. The alternating current (AC) component varies more
Erin L. McCleave, Katie M. Slattery, Rob Duffield, Philo U. Saunders, Avish P. Sharma, Stephen Crowcroft and Aaron J. Coutts
&D Systems Inc, Minneapolis, MN, coefficient of variation = 5.4%). Assays were conducted on a SpectraMax 190 microplate reader (Molecular Devices LLC, Sunnyvale, CA). Prior to analysis, measures were adjusted for PV differences. 22 Plasma and Blood Volume Plasma volume and blood volume were indirectly
Myriam Paquette, François Bieuzen and François Billaut
delivery to and extraction by the muscle, while [THb] serves as an indicator of local blood volume. 15 The deoxyhemoglobin concentration ([HHb]), representing muscle O 2 extraction, was computed from SmO 2 and [THb] using the following equation: [HHb] = [THb] − SmO 2 × [THb]. 15 Baseline SmO 2 and
Philippe Richard, Lymperis P. Koziris, Mathieu Charbonneau, Catherine Naulleau, Jonathan Tremblay and François Billaut
bioenergetics requirements of the quadriceps muscles, as robustly demonstrated by the near-infrared spectroscopy-derived decrease in blood volume and muscle tissue oxygenation, 31 and they probably explain the high [lactate] reported here and elsewhere. 30 Therefore, it can be hypothesized that the