Postactivation Potentiation Improves Performance in a Resistance Training Session in Trained Men.

ABSTRACT: Alves, RR, Viana, RB, Silva, MH, Guimarães, TC, Vieira, CA, Santos, DdAT, and Gentil, PRV. Postactivation potentiation improves performance in a resistance training session in trained men. J Strength Cond Res 35(12): 3296-3299, 2021-This study aims to analyze the influence of postactivation potentiation (PAP) on performance during a resistance training (RT) session in trained individuals. Fourteen trained men (25.0 ± 3.5 years; 89.9 ± 16.3 kg; 1.77 ± 0:08 m; 28.0 ± 4.0 kg·m-2; and 5 ± 4 years of RT experience) were tested in 2 situations: with PAP and without PAP (CON). Both situations involved 3 sets of the bench press exercise performed to muscle failure at 75% of the 1 repetition maximum load and with 1.5-minute interval between sets. Total work was greater (p < 0.001) for PAP (1,601 ± 504 kg) than for CON (1,379 ± 364 kg). The number of repetitions performed in the first and second sets of PAP (11.5 ± 3.1 and 6.5 ± 1.9, respectively) were greater (p < 0.05) than those performed in CON (10.4 ± 2.7, 5.5 ± 1.8, respectively). No significant difference was found in the number of repetitions in the last set between the situations. The present study suggests that PAP might be beneficial to improve total work and performance during multiple sets of RT in trained men. Therefore, PAP might be used during RT to promote higher total work and potentially increase results over long term. Thus, the protocol can use in sports centers, fitness centers, and gyms per coaches and athletes to increase performance and total work in trained individuals.

Effects of Static and Dynamic Stretching Performed Before Resistance Training on Muscle Adaptations in Untrained Men.

ABSTRACT: Ferreira-Júnior, JB, Benine, RPC, Chaves, SFN, Borba, DA, Martins-Costa, HC, Freitas, EDS, Bemben, MG, Vieira, CA, and Bottaro, M. Effects of static and dynamic stretching performed before resistance training on muscle adaptations in untrained men. J Strength Cond Res 35(11): 3050-3055, 2021-This study evaluated the effects of dynamic and static stretching (SS) performed before resistance training on biceps femoris hypertrophy and knee flexor strength gains in untrained young men. Forty-five untrained young men (age, 21.2 ± 0.5 years; mass, 72.2 ± 5.6 kg; height, 178 ± 1 cm) were randomly assigned to 1 of the 3 groups: (a) 80 seconds of SS (n = 14); (b) 80 seconds of dynamic stretching (DS, n = 13); or (c) control group (CON, n = 18) in which subjects performed no stretching before exercise. Both SS and DS were performed before resistance exercise. Resistance training consisted of 4 sets of 8-12 repetition maximum of seated leg curl exercise 2 days per week for 8 weeks, with a period of at least 48 hours between sessions. Unilateral biceps femoris muscle thickness (MT) and maximal isometric strength (MIS) of the knee flexors were measured 1 week before training and 1 week after the last training session. There were significant increases in MIS (SS = 13.9 ± 10.3 kgf; DS = 10.2 ± 13.1 kgf; CON = 12.7 ± 7.6 kgf; p < 0.05) and MT (SS = 6.0 ± 3.5 mm; DS = 6.7 ± 4.1 mm; CON = 5.7 ± 3.0 mm; p < 0.05) with no significant differences across groups (p > 0.05). Additionally, all groups demonstrated moderate effect sizes for MIS (1.27-1.4), and DS was the only group that had a large effect size for MT increases (DS = 2.18; SS = 1.35; CON = 0.92). In conclusion, 80 seconds of SS and DS did not induce any additional muscular adaptations to resistance training in untrained young men.

Resistance Training Performed to Failure or Not to Failure Results in Similar Total Volume, but With Different Fatigue and Discomfort Levels.

ABSTRACT: Santos, WDNd, Vieira, CA, Bottaro, M, Nunes, VA, Ramirez-Campillo, R, Steele, J, Fisher, JP, and Gentil, P. Resistance training performed to failure or not to failure results in similar total volume, but with different fatigue and discomfort levels. J Strength Cond Res 35(5): 1372-1379, 2021-The purpose of this study was to compare the acute response to 4 sets of high velocity parallel squats performed to momentary failure (MF) or not to momentary failure (NF). Twelve women (24.93 ± 5.04 years) performed MF and NF protocols, in a randomized order with 2-3 interday rest. The protocol involved 4 sets of parallel squats executed at high velocity at 10RM load, with 2 minutes of rest interval between sets. During the NF protocol, the sets were interrupted when the subject lost more than 20% of mean propulsive velocity. The analysis involved the number of repetitions performed per set, total number of repetitions, movement velocity loss, power output loss, rating of perceived exertion (RPE), rating of perceived discomfort (RPD), and session rating of perceived exertion (sRPE). Compared with NF, MF resulted in a higher number of repetitions in the first set (11.58 ± 1.83 vs. 7.58 ± 1.72, p < 0.05), but a lower in the last set (3.58 ± 1.08 vs. 5.41 ± 1.08, p < 0.05). Total number of repetitions was similar between the protocols (MF 26.25 ± 3.47 vs. NF 24.5 ± 3.65, p > 0.05). In both protocols, there were significant decreases in maximum and mean movement velocity loss and power output loss, but higher decreases were observed in MF than NF (p < 0.05). Values for RPE, sRPE, and RPD were higher during MF than NF (p < 0.05). Controlling the movement velocity in NF protocol enabled performance of a similar total volume of repetitions with lower movement velocity and power output losses, RPE, sRPE, and RPD than during an MF protocol.

Resistance Training, Fatigue, Quality of Life, Anxiety in Breast Cancer Survivors.

ABSTRACT: Moraes, RF, Ferreira-Júnior, JB, Marques, VA, Vieira, A, Lira, CAB, Campos, MH, Freitas-Junior, R, Rahal, RMS, Gentil, P, and Vieira, CA. Resistance training, fatigue, quality of life, anxiety in breast cancer survivors. J Strength Cond Res 35(5): 1350-1356, 2021-Resistance training (RT) has shown to be effective in improving fatigue, quality of life (QOL), and anxiety levels among breast cancer survivors (BCS), but there is no consensus as to how this practice should be prescribed for optimal performance. This study analyses the effects of once weekly RT on fatigue, QOL, and anxiety levels among BCS. Randomized controlled trial. Twenty-five BCS (aged 54.6 ± 5.5 years) were randomized into RT or control groups. The RT group performed 8 weeks of RT (once per week). Fatigue was assessed using the Piper Fatigue scale, QOL was assessed using the SF-36, and anxiety was assessed using the STAI State-Trait Anxiety Inventory. Resistance training significantly improved the following subscales of SF-36: aspects of physical functioning (+27%, p = 0.027); physical role functioning (+54%, p = 0.008); emotional role functioning (+42%, p = 0.027); and mental health (+16%, p = 0.032). Furthermore, RT improved fatigue levels (-55%, p = 0.001 for general fatigue) and anxiety (anxiety state, -19%, p = 0.012; anxiety trait, -23%, p = 0.001). Resistance training seemed to be a positive nonpharmacological tool for the reduction of fatigue, anxiety, and for improvement of several aspects of QOL in BCS.

The geometric curvature of the spine during the sirshasana, the yoga's headstand.

This study analysed the behaviour of the geometric curvature of the spine during sirshasana. The position of dorsal retroreflective markers was computed via stereophotogrammetric analysis in six males and five females (29.4 ± 8.8 years, 63.0 ± 11.4 kg, 1.66 ± 0.08 m [average ± standard deviation]). The spinal points were projected onto the sagittal and frontal planes of the trunk, a polynomial was fitted to the data and the two-dimensional geometric curvature was quantified. The inferior lumbar lordosis decreased compared to the orthostatic position and gait, which may favour the posterior protrusion of the lumbar spinal nucleus pulposus in people with posterior herniation. The lateral deviation at the middle of the thoracic spine increases during sirshasana, which may reflect increased difficulties for postural control and spinal loads. It could be useful for promoting positive spinal structural and functional chronic adaptations for healthy participants, if the yoga programme is carefully planned and the spinal alignment is carefully monitored during a headstand. However, it may aggravate some spinal diseases, especially scoliosis.

Effect of both dance exergame and a traditional exercise on state anxiety and enjoyment in women.

BACKGROUND: Anxiety disorders affect many people around the world and women are more affected than men. Physical exercise might be an important nonpharmacological tool to ameliorate these disorders. The aim of this study was to compare state anxiety level and enjoyment between a dance exergame session and a traditional aerobic exercise. METHODS: Twenty healthy young women completed 3 visits, on separate days. At the first visit, participants performed a graded exercise testing and familiarization procedures. In other two visits, participants completed two exercise sessions (dance exergame and traditional aerobic exercise), with similar intensities and duration. Each session lasted approximately 45 minutes. State anxiety level was evaluated before, immediately post- and 10 minutes post-sessions. Enjoyment was evaluated immediately post-sessions. RESULTS: There was a significant interaction between session and time (P<0.001), a main effect of time (P=0.007) but no significant main effect of session (P=0.057) on state anxiety level. State anxiety level immediately post (P<0.001) and 10 minutes postsession (P<0.001) were significantly lower than predance exergame session. There were no significant changes between pre-, immediately post and 10 minutes post-traditional aerobic exercise session (P>0.05). State anxiety level at immediately post dance exergame session was significantly lower than immediately post traditional aerobic exercise session (P=0.026). Dance exergame session was significantly more enjoyable than traditional aerobic exercise session (P<0.0001). CONCLUSIONS: Dance exergames might be used as a tool to reduce anxiety level in young women.

Effects of Chemotherapy Treatment on Muscle Strength, Quality of Life, Fatigue, and Anxiety in Women with Breast Cancer.

The study aimed to evaluate the effects of chemotherapy treatment on muscle strength, quality of life, fatigue, and anxiety in women with breast cancer. Nineteen women who were undergoing a chemotherapy treatment (breast cancer treatment [BCT] group, 52.2 ± 13.1 years) and 18 women without cancer (control [CNT] group, 55.8 ± 8.4 years) answered questionnaires for evaluation of fatigue (Fatigue Scale), quality of life (Short-Form Healthy Survey [SF-36] questionnaire), and anxiety (State-Trait Anxiety Inventory [IDATE]) levels. Muscle strength was also assessed by an isometric grip test and an isokinetic knee extension test. Physical limitations, social and emotional domains of quality of life were lower in the BCT group in comparison to the CNT group (p = 0.002; p = 0.003; p = 0.0003, respectively). The other domains did not differ between groups (p > 0.05). There were no differences in fatigue and anxiety levels between both the BCT and CNT groups (p > 0.05). Additionally, isometric grip strength was higher in the CNT group when compared to the BCT group (p = 0.048). However, there were no differences between the BCT and CNT groups for peak torque and total work at both 60°.s-1 (p = 0.95 and p = 0.61, respectively) and 180°.s-1 (p = 0.94 and p = 0.72, respectively). These results suggest that three cycles of chemotherapy treatment may impair handgrip isometric strength and quality of life in women with breast cancer.

Effects of a low-volume plyometric training in anaerobic performance of adolescent athletes.

BACKGROUND: Parameters related to the anaerobic capacity and power may be important for the performance of many sports whose skills are related to high-intensity and short-duration efforts. Although plyometric training (PT) has been widely used in the regular strength and conditioning programs of young athletes, its effects on anaerobic performance are still controversial. Therefore, the purpose of the present study was to evaluate the effects of PT in anaerobic performance in young athletes. METHODS: Twenty-nine adolescent athletes participated in this 10-week study. Baseline and post intervention testing included Flying Start 30 m Sprint Test (F30), 1600 m, and Running-based Anaerobic Sprint Test (RAST). Subjects were divided in two groups: one completed only their regular training sessions, thus serving as the control (CON, N.=15), whereas the other performed the regular training plus twice-weekly low-volume plyometric training (PLYO, N.=14). RESULTS: PLYO groups had significant increases in all variables analyzed. The novel findings were the increase in F30 performance (4.22% for PLYO vs. 1.08% for CON), the decreases in Fatigue Index (9.9% for PLYO vs. 1.53% for CON), and increases in minimum (19.41% for PLYO vs. 0.29 for CON), mean (14.7% for PLYO vs. 0.16% for CON) and peak power (10.88% for PLYO vs. 0.81% for CON) during the RAST Test. CONCLUSIONS: Considering that anaerobic performance is an important feature in many sports, our results suggests that coaches involved with strength and conditioning of youth athletes should consider the inclusion PT in their training periodization.

Defining the number of bouts and oxygen uptake during the "Tabata protocol" performed at different intensities.

It is usually reported that the Tabata protocol (TP) is performed with eight bouts of 20:10 intervals at a load equivalent to 170% of i V̇ O2max. However, the feasibility of accumulating 160 s of work at 170% i V̇ O2max has been questioned. This article tested the intensity that would allow the performance of the original TP on a cycle ergometer, and measured the highest value of oxygen consumption (V̇ O2) obtained during the TP and the time spent above 90% of the maximal oxygen uptake (V̇ O2max) during the TP performed at different intensities. Thirteen young active males (25.9 ±â€¯5.5 years, 67.9 ±â€¯9.2 kg, 1.70 ±â€¯0.06 m, 23.6 ±â€¯3.1 kg·m-2) participated in the study. Participants performed a graded exertion test (GXT) on a cycle ergometer to obtain maximum oxygen consumption (V̇ O2max) and the intensity associated with V̇ O2max (i V̇ O2max). V̇ O2, maximal heart rate (HRmax), and number of bouts performed were evaluated during the TP performed at 115%, 130%, and 170% of i V̇ O2max. V̇ O2max, HRmax, and iV̇ O2max were 51.8 ±â€¯8.0 mL.kg-1·min-1, 186 ±â€¯10 bpm, and 204 ±â€¯26 W, respectively. The number of bouts performed at 115% (7 ±â€¯1 bouts) was higher than at 130% (5 ±â€¯1 bouts) and 170% (4 ±â€¯1 bouts) (p < .0001). The highest V̇ O2 achieved at 115%, 130%, and 170% of iV̇ O2max was 54.2 ±â€¯7.9 mL·kg-1·min-1, 52.5 ±â€¯8.1 mL·kg-1·min-1, and 49.6 ±â€¯7.5 mL·kg-1·min-1, respectively. Non significant difference was found between the highest V̇ O2 achieved at different intensities, however qualitative magnitude-inference indicate a likely small effect between 115% and 170% of iV̇ O2max. Time spent above 90% of the V̇ O2max during the TP at 115% (50 ±â€¯48 s) was higher than 170% (23 ±â€¯21 s; p < 0.044) with a probably small effect. In conclusion, our data suggest that the adequate intensity to perform a similar number of bouts in the original TP is lower than previously proposed, and equivalent to 115% of the iV̇ O2max. In addition, intensities between 115 and 130% of the iV̇ O2max should be used to raise the time spent above 90% V̇O2max.

Profiling exercise intensity during the exergame Hollywood Workout on XBOX 360 Kinect®.

BACKGROUND: Despite the increasing popularity of exergame practice and its promising benefits in counteracting physical inactivity, limited research has been performed to document the physiological responses during an exergame session. This study aims (i) to investigate the responses of heart rate (HR) and oxygen uptake ( V˙O2 ) during an exergame session and to compare with HR and V˙O2 measured during joystick session and (ii) to compare HR and V˙O2 obtained during exergame and joystick session with those HR and V˙O2 associated with first and second ventilatory thresholds (VT1 and VT2, respectively) obtained during a maximal graded exercise test. METHODS: A total of 39 participants performed a maximal graded exercise test to determine maximal oxygen uptake ( V˙O2max ), VT1, and VT2. On separate days, participants performed an exergame and traditional sedentary game (with a joystick) sessions. The time that participants remained with HR and V˙O2 below the VT1, between the VT1 and VT2 and above the VT2 were calculated to determine exercise intensity. RESULTS: Heart rate and V˙O2 were below VT1 during 1,503 ± 292 s (86.1 ± 16.7%) and 1,610 ± 215 s (92.2 ± 12.3%), respectively. There was an increase in HR and V˙O2 as a function of exergame phases, since HR mean values in the 'warm-up' period (119 ± 13 bpm) were lower than the 'main phase' (136 ± 15 bpm) and 'cool-down' periods (143 ± 15 bpm) (p < 0.001). Regarding V˙O2 values, the 'warm-up' (25.7 ± 2.9 mL.kg-1.min-1) were similar to the 'main phase' (25.1 ± 2.8 mL.kg-1.min-1) (p > 0.05) and lower than the 'cool-down' (28.0 ± 4.8 mL.kg-1.min-1) (p < 0.001). For all times of the joystick session, average HR and V˙O2 were below the VT1 levels. CONCLUSION: Exergames can be classified as light to moderate exercise. Thus, exergames could be an interesting alternative to traditional forms of exercise.

Effects of Different Conditioning Activities on 100-m Dash Performance in High School Track and Field Athletes.

This study compared the effects of different conditioning activities on the 100-m dash performance of 11 male, high school track and field athletes (mean age = 16.3; SD = 1.2 years). Participants performed a 100-m dash seven minutes after each of four randomized conditioning protocols, with each condition and 100-m dash separated by 3-10 days. The conditioning protocols were (a) control, no conditioning activity; (b) weighted plyometric, three sets of 10 repetitions of alternate leg bounding with additional load of 10% of the body mass; (c) free sprint, two 20-m sprints; and (d) resisted sprint (RS), two 20-m resisted sprints using an elastic tubing tool. We obtained session ratings of perceived exertion (SRPE) immediately after each conditioning protocol. There were no significant differences between any of the three experimental conditioning activities on 100-m sprint time, but the RS protocol improved 100-m sprint time compared with the control (no conditioning) protocol ( p < .001). The RS also led to greater sprint velocity and higher SRPE compared with the control condition ( p < .01). There was no significant association between SRPE and 100-m performance ( p = .77, r = .05). These results suggest a benefit for young male track and field athletes to the elastic tubing warm-up activities prior to the 100-m dash.

Identifying the predisposing factors, signs and symptoms of overreaching and overtraining in physical education professionals.

BACKGROUND: It is possible that physical education professionals, especially those who participate in aerobic activities, have predisposing factors, signs and symptoms of overreaching (OVR) and overtraining (OVT) due to a high load and volume of exercise followed by suboptimal recovery time. The present study aimed to identify the predisposing factors, signs and symptoms of OVR and OVT in physical education professionals. METHODS: A questionnaire consisting of 42 questions (10 questions group) about predisposing factors and signs/symptoms was answered by 132 physical education professionals from both sexes (83 men and 49 women) who were allocated into a resistance training group (RG, n = 74), aerobic training group (AG, n = 20) and resistance and aerobic training group (RAG, n = 38). A mean score was calculated ranging from 1 (completely absent) to 5 (severe) for each question group. A low occurrence of predisposing factors and signs and symptoms of OVR and OVT was considered to be a question group score 4 or lower. Profile of Mood State Questionnaire (POMS) was also applied. RESULTS: A mean score of 2.5 ± 0.7, 2.7 ± 0.7 and 2.7 ± 0.8 was found for all question groups for RG, AG and RAG, respectively. Of the total sample, 40.6% trained at least five times/week. The POMS revealed that 67.5% of the RG (n = 50), 80% of the AG (n = 16) and 60.5% of the RAG (n = 23) were classified as having no mood disorders and a standard graphic iceberg was presented. There were no statistical differences (p > 0.05) in the total mood disorders among RG (13.9 ± 24.5), AG (10.3 ± 25.1) and RAG (14.6 ± 27.9) groups. CONCLUSION: Despite the volume of training/body working performed by the physical education professionals surveyed being greater than the recommended to achieve improvements on physical fitness, they did not show predisposing factors, signs or symptoms of OVR and OVT.

The geometric curvature of the lumbar spine during restricted and unrestricted squats.

BACKGROUND: The main purpose of this study was to analyze the behavior of the geometric curvature of the lumbar spine during restricted and unrestricted squats, using a novel investigative method. The rationale for our hypothesis is that the lumbar curvature has different patterns at different spine levels depending on the squat technique used. METHODS: Spine motion was collected via stereo-photogrammetric analysis in nineteen participants (11 males, 8 females). The reconstructed spine points at the upright neutral position and at the deepest position of the squat exercise were projected onto the sagittal plane of the trunk, a polynomial was fitted to the data, and were quantified the two-dimensional geometric curvature at lower, central and higher lumbar levels, besides the inclination of trunk and lumbosacral region, the overall geometric curvature and overall angle of the lumbar spine. The mean values for each variable were analysed with paired t-test (P<0.05). RESULTS: The lumbar presents a flexion from upright neutral posture to deepest point of the movement, but for the lower lumbar the flexion is less intense if the knees travel anteriorly past the toes. The trunk and the lumbosacral region lean forward in both squat techniques and these effects are also reduced in unrestricted squats. CONCLUSIONS: The data collected in the study are evidence that during barbell squats the lumbar curvature has different patterns at different spinal levels depending on the exercise technique. The lower lumbar spine appears to be less overloaded during unrestricted squats.

Structural resistance of orthodontic mini-screws inserted for extraalveolar anchorage / Resistência estrutural de mini-aparafusos ortodônticos inseridos para ancoragem extra-alveolar

ABSTRACT The risk of fracture or strain in mini-screws is higher if diameter, length, type of alloy or insertion angle is selected inappropriately. The aims of this study were to test the structural resistance of two types of orthodontic mini-screws -one made of stainless steel and another of titanium- from an international brand and to evaluate the efficacy of two other titanium miniscrews of Brazilian origin, during an extra-alveolar anchorage procedure. The mini-screws analyzed were: Bomei stainless steel and Bomei titanium/Taiwan, Morelli titanium and Neodent titanium/ Brazil. Experiments were conducted on pig mandibles to simulate the process of extra-alveolar anchorage. Two insertion processes were used: Direct at 30°, and Indirect, starting at 60° and ending at 30° with gradual continuous movement. Strain was evaluated using Optical and Scanning Electron Microscopy. Data were evaluated using Kruskal-Wallis non-parametric statistical analysis and post hoc Tamhane test. Significant statistical differences in strain were observed among the mini-screws used in the extra-alveolar insertions, both for the direct and indirect procedures. In the indirect insertion tests, both stainless steel and titanium mini-screws suffered deformation, showing that angling can be an important factor in mini-screw failure rates. The change in angle during the insertion movement increased deformation rates independently of alloy type, increasing the risk offailure. These results could help orthodontists in choosing mini-screws for extra-alveolar anchorage, which can be performed with direct or indirect insertion. In vivo studies should be conducted to confirm the findings of this study.

RESUMO O risco de fratura ou tensao nos mini-parafusos é maior se o diámetro, comprimento, tipo de liga ou ángulo de insergao for selecionado de forma inadequada. Os objetivos deste estudo foram testar a resistencia estrutural de dois tipos de mini-aparafusos ortodónticos -um feito de ago inoxidável e outro de titànio- de uma marca internacional e avaliar a eficácia de dois outros mini-parafusos de titànio de origem brasileira, durante um procedimento de ancoragem extra-alveolar. Os mini-aparafusos analisados foram: Bomei ago inoxidável e Bomei titànio / Taiwan, Morelli titànio e Neodent titànio / Brasil. Foram realizadas experiencias em mandíbulas de porcos para simular o processo de ancoragem extra-alveolar. Foram utilizados dois processos de insergao (Direta a 30°, e Indireta, comegando a 60° e terminando a 30° com movimento gradual continuo). A deformagao foi avaliada utilizando Microscopia Optica e Microscopia Eletrónica de Varredura. Os dados foram avaliados utilizando análise estatistica nao paramétrica Kruskal-Wallis e testepost-hoc Tamhane. Diferengas estatisticas significativas na deformagao foram observadas entre os mini-parafusos utilizados nas insergoes extra-alveolares, tanto para os procedimentos diretos como indiretos. Nos testes de insergao indireta, tanto os mini-parafusos de ago inoxidável como os de titánio sofreram deformagao, mostrando que a angulagao pode ser um fator importante nas taxas de falha dos mini-parafusos. A mudanga no ángulo durante o movimento de insergao aumentou as taxas de deformagao independentemente do tipo de liga, aumentando o risco de falha. Estes resultados podem ajudar os ortodontistas na escolha de mini-parafusos para ancoragem extra-alveolar, que pode ser realizada com insergao direta ou indireta. Estudos in vivo devem ser conduzidos para confirmar os resultados deste estudo.

Session rating of perceived exertion following resistance exercise with blood flow restriction.

Session ratings of perceived exertion (SRPE) provide a valid and reliable indicator of resistance exercise session intensity. However, there is a lack of studies on the effects of resistance exercise with blood flow restriction (BFR) on SRPE. Thus, the aim of this study is to compare the effects of resistance exercise at high intensity versus low intensity with BFR on internal training load measured by SRPE. Thirteen young (22.2 ± 3.8 years) resistance-trained men (training experience 3.2 ± 2.4 years) participated in the study protocol. After determining one maximum repetition (1-RM), the subjects were assigned to two groups in a counterbalanced design (i) high-intensity exercise (HIE, performed one training session at 80% of 1-RM) and (ii) low intensity with BFR (BFR, performed an exercise session at 50% of 1-RM with BFR). During each session, subjects performed three sets of unilateral elbow flexion leading to concentric failure with a 1-min rest interval between sets. A cuff around the arm, inflated at 110 mmHg, was used continuously for BFR. The SRPE was reported 30 min after the end of the session. The low intensity with BFR showed lower total work (197.13 ± 63.49 versus 300.92 ± 71.81 kg; P = 0.002) and higher SRPE (9 versus 6; P = 0.007) than high-intensity resistance exercise. The present results indicate that BFR is an important factor to increase internal training load. Future studies should investigate the physiological stress imposed by different training methods rather than just quantify the external training load such as intensity or volume.

Alkylation of myotoxic phospholipases A2 in Bothrops moojeni venom: a promising approach to an enhanced antivenom production.

Bothrops moojeni crude venom (MjCV) and its two major toxins, namely myotoxin I (MjTX-I) and myotoxin II (MjTX-II) were alkylated by p-bromophenacyl bromide (BPB). After alkylation the i.p. LD(50) (mice) of MjCV and MjTX-I/II increased from 6.0 to 15.7mg/kg and from 8.0 to 45.0mg/kg, respectively. In addition, doses of 5x LD(50) of alkylated MjTX-I did not cause a single death in mice and no myonecrosis was detected for the alkylated toxins, although both proteins still induced edema. Antibodies to native and modified crude venom or myotoxins cross-reacted with 12 purified class II myotoxic phospholipases A(2) found in snake venoms of the genus Bothrops. Myotoxic PLA(2)s from class I and class III were not recognized by the above antibodies. These results suggest that the overall antigenic structure is conserved among class II myotoxic PLA(2)s, despite differences in their amino acid sequences. Anti-MjTX-I-BPB and anti-MjTX-II-BPB rabbit serum, obtained against the modified myotoxins, were apparently more efficient than those obtained against the native myotoxins. In neutralization experiments, pre-incubation of crude venom or isolated myotoxins with antibodies raised against the native or modified toxins inhibited their PLA(2) and myotoxic activities. Therefore, alkylation of His48 by BPB strongly reduces the local tissue damage induced by B. moojeni venom or isolated myotoxins while retaining antigenicity, which suggests a promising procedure for an enhanced antiophidian serum production for practical purposes.

Mn(2+) ions reduce the enzymatic and pharmacological activities of bothropstoxin-I, a myotoxic Lys49 phospholipase A(2) homologue from Bothrops jararacussu snake venom.

Bothropstoxin-I (BthTX-I), a myotoxic Lys49 phospholipase A(2) (PLA(2)) homologue isolated from Bothrops jararacussu snake venom, causes a range of biological effects, including myonecrosis, mouse paw edema, irreversible neuromuscular blockade and lysis of cell cultures. Among eight divalent cations assayed, Mn(2+) was the most effective in reducing mouse paw edema induced by BthTX-I (25 microg). Preincubating BthTX-I with Mn(2+) (1.0mM) reduced mouse paw edema by 70% and myotoxicity by 60% in mice injected i.m. with 50 microg toxin. Mn(2+) (50 microl of a 1mM solution) administered within 1min at the site of toxin injection was still but less effective in antagonising BthTX-I-induced myotoxicity. Mn(2+) (1.0mM) completely prevented BthTX-I (1.4 microM)-induced neuromuscular blockade in the mouse phrenic-nerve diaphragm preparation. Mn(2+) (0.25mM) protected about 85% of NB41A3 cells from lysis when coincubated with BthTX-I (1.0 microM) for 25h. Preincubation with 0.25mM Mn(2+) increased the sensitivity of the cells to subsequent lysis by BthTX-I in the absence of Mn(2+). BthTX-I (1 microM) caused extensive fatty acid release (from 0.8% of the total radiolabeled lipid in control cells to 56% with toxin) when incubated with the NB41A3 cell line for 25h. PLA(2) activity observed in cell cultures after addition of BthTX-I was considerably reduced by 0.25mM Mn(2+). Mn(2+) ions constitute a promising agent to assess the action mechanism and the effects of enzymatic inhibition on the pharmacological activity of Lys49 PLA(2) homologues.

Rituximab for reduction of anti-HLA antibodies in patients awaiting renal transplantation: 1. Safety, pharmacodynamics, and pharmacokinetics.

BACKGROUND: Preformed HLA antibodies (Ab), reported as panel-reactive antibody (PRA), prolong patient waiting time for kidney transplantation. We hypothesized that rituximab (RTX) could reduce PRA via B-cell depletion. This initial study reports the safety, pharmacokinetics, and pharmacodynamics of RTX in patients with end-stage renal failure. METHODS: The study was an investigator-initiated single-dose, dose-escalation phase I trial of RTX in chronic dialysis patients (PRA >50%). It was approved by the Institutional Review Board and the Food and Drug Administration. Nine subjects were treated with a single dose of RTX (n=3 per group) at 50, 150, or 375 mg/m. Peripheral lymphocyte cell surface markers and HLA Ab levels (%PRA and titers) were tested using flow cytometry. RESULTS: There were four significant adverse events: a suspected histoplasmosis infection; two Tenchkoff dialysis catheter infections; and fever (38.7 degrees C) during infusion. At 2 days after RTX therapy, there was depletion of CD19 cells (pre-RTX 181+/-137 vs. post-RTX 12+/-5.6, P =0.006). In 2 (22%) of 9 subjects, there was no appreciable change in PRA. Among the other seven patients, one had a decrease in PRA from 87% to 51% with a concurrent decrease in fluorescence intensity; five patients had changes in histogram architecture suggesting loss of antibody specificity; and one patient had a fourfold decrease in PRA titer from 1:64 to 1:16 at 6 months after treatment. In addition, one of the seven patients converted a donor-specific crossmatch to negative and underwent a successful living donor kidney transplantation. CONCLUSIONS: RTX can be safely administered and may be an effective agent to reduce high-titer anti-HLA Abs in subjects awaiting kidney transplantation.

In vivo human B-cell subset recovery after in vivo depletion with rituximab, anti-human CD20 monoclonal antibody.

Rituximab, chimeric anti-human CD20 monoclonal antibody approved for B-cell lymphoma, depletes circulating B cells. Little data exist on its use for nonmalignant diseases or B-cell subset recovery after treatment. We hypothesized that rituximab may reduce panel reactive alloantibodies (PRA) in dialysis patients awaiting renal transplantation and performed a single-dose, dose-escalation phase 1 trial. Here we report changes in lymphocyte phenotypes in subjects treated with rituximab alone. Nine subjects, 44 +/- 10 years(Yr); (5 F, 4 M) received one dose (n=3) at 50, 150, or 375 mg/m(2) without other immunosuppression. Blood was collected before dosing and intervals thereafter. No significant changes in leukocytes, total or CD3(+) lymphocytes were noted. In all, there was CD19(+) depletion by day 2(D2) (12.0 +/- 5.6 cells/mm(3) vs. 181 +/- 137, D0; p<0.01) and CD20(+) (11.0 +/- 12.0 vs. 205 +/- 116, D0; p<0.01). At 6 months (mo), CD19(+) and CD20(+) remained low (51.1 +/- 42.2, p<0.05; 75.4 +/- 38.7, p<0.05, respectively) compared to D0. CD19(+)CD5(+) cells recovered more rapidly, returning to baseline by 6mo while B memory cells (CD19(+)CD27(+)) remained low (32.3 +/- 29.0) at 1Yr (7.5 +/- 4.5; p<0.001) and 2Yr (12.1 +/- 7.9; p<0.001) after treatment. We conclude that single dose rituximab ablates B cells in high PRA dialysis patients awaiting transplantation. B-cell ablation, particularly memory B cells, was long-lasting, lagging repopulation by CD5(+) B cells.

Quantification of nicotine in commercial brand cigarettes: How much is inhaled by the smoker?

The main objective of this experiment is to determine the amount of nicotine in commercial brand cigarettes by means of a nonaqueous acid-base titration. A simple glass device simulating a smoker is proposed, which allows the determination of the volatilized, filter retained, and inhaled portions. Students will readily see that the amount of nicotine/cigarette stated on the label (∼0.5-1.0 mg) refers indeed to the inhaled portion only, rather than to the total amount/cigarette (usually more than 10 mg). Even so, values for inhaled nicotine may be significantly higher than those reported for several brands. Students will also be able to make a critical evaluation of the true content of nicotine in the inhaled portion and confront it with the reported value for a given brand. In addition, the theoretical approach, supported by HPLC data, provides an excellent experience on nonaqueous acid-base volumetric analysis.