Load-Time and Load-Speed Relationship in the Resisted Sled Sprint Exercise: What Independent Variable Most Accurately Determines the Relative Load?

ABSTRACT: Jiménez-Lozano, M, Yáñez-García, JM, Mora-Custodio, R, Valle-Salguero, A, Díez-Fernández, DM, Franco-Márquez, F, González-Badillo, JJ, and Rodríguez-Rosell, D. Load-time and load-speed relationship in the resisted sled sprint exercise: what independent variable most accurately determines the relative load? J Strength Cond Res 37(11): 2167-2177, 2023-The aims of this study were to analyze the load-speed and load-time relationships in the resisted sled sprint exercise using different variables as relative load and to estimate the decrement of speed sprint and the increase of sprint time across different loads. Thirty young healthy men performed a progressive loading test in the countermovement jump (CMJ) exercise to determinate the load that elicited a 2 m·s-1 peak velocity (PV2-load) and in the full squat exercise to obtain the 1 repetition maximum (1RM) value and the load that elicited a 1 m·s-1 mean velocity (V1-load). In addition, subjects performed a progressive loading test in the resisted sled sprint exercise, whereas time and instantaneous speed at 10 (T10 and V10) and 20 m (T20 and V20) were measured. The independent variables used were body mass (BM), 1RM and V1-load in the squat exercise, the PV2-Load in the loaded CMJ exercise, 1RM + BM, V1-Load + BM, and PV2-Load + BM. To analyze whether relationships were dependent on individual performance obtained in unloaded sprint, the total sample was divided into 3 subgroups: high performance (T20 < 3.00 s), medium performance (T20:3.00-3.12 s), and low performance (T20 > 3.12 seconds) groups. The independent variables showing the highest relationships with time and speed in 10 and 20 m were %BM, %BM + V1-load, and %BM + PV2-load. Statistically significant differences between performance groups in %DSS (decrease of sprint speed) and %IST (increase sprint time) in 20 m were found when %BM was used as relative load, whereas there were no significant differences between groups for %BM + PV2-load or %BM + V1-load. In conclusion, the use of %BM + PV2-load and %BM + V1-load should be considered as variables for monitoring the relative load in the resisted sled sprint exercise.

Imbalanced IL-1B and IL-18 Expression in Sézary Syndrome.

Sézary syndrome (SS) is a rare and aggressive type of cutaneous T-cell lymphoma, with an abnormal inflammatory response in affected skin. The cytokines IL-1B and IL-18, as key signaling molecules in the immune system, are produced in an inactive form and cleave to the active form by inflammasomes. In this study, we assessed the skin, serum, peripheral mononuclear blood cell (PBMC) and lymph-node samples of SS patients and control groups (healthy donors (HDs) and idiopathic erythroderma (IE) nodes) to investigate the inflammatory markers IL-1B and IL-18 at the protein and transcript expression levels, as potential markers of inflammasome activation. Our findings showed increased IL-1B and decreased IL-18 protein expression in the epidermis of SS patients; however, in the dermis layer, we detected increased IL-18 protein expression. In the lymph nodes of SS patients at advanced stages of the disease (N2/N3), we also detected an enhancement of IL-18 and a downregulation of IL-1B at the protein level. Moreover, the transcriptomic analysis of the SS and IE nodes confirmed the decreased expression of IL1B and NLRP3, whereas the pathway analysis indicated a further downregulation of IL1B-associated genes. Overall, the present findings showed compartmentalized expressions of IL-1B and IL-18 and provided the first evidence of their imbalance in patients with Sézary syndrome.

Infection-elicited microbiota promotes host adaptation to nutrient restriction.

The microbiota performs multiple functions vital to host fitness, including defense against pathogens and adaptation to dietary changes. Yet, how environmental challenges shape microbiota resilience to nutrient fluctuation remains largely unexplored. Here, we show that transient gut infection can optimize host metabolism toward the usage of carbohydrates. Following acute infection and clearance of the pathogen, mice gained more weight as a result of white adipose tissue expansion. Concomitantly, previously infected mice exhibited enhanced carbohydrate (glucose) disposal and insulin sensitivity. This metabolic remodeling depended on alterations to the gut microbiota, with infection-elicited Betaproteobacteria being sufficient to enhance host carbohydrate metabolism. Further, infection-induced metabolic alteration protected mice against stunting in the context of limited nutrient availability. Together, these results propose that alterations to the microbiota imposed by acute infection may enhance host fitness and survival in the face of nutrient restriction, a phenomenon that may be adaptive in settings where both infection burden and food precarity are prevalent.

An Exploratory Mixed Method Cross-Sectional Study to Identify Opportunities to Increase Enrollment and Retention of Native Hawaiian Students in an Undergraduate Dietetic Program.

BACKGROUND: Native Hawaiians (NH) are underrepresented in dietetics, contributing to less than 1% of the profession nationally. Increasing the number of NH Registered Dietitian Nutritionists (RDN) is one mechanism to facilitate improved health outcomes in disparate populations. OBJECTIVES: 1) Identify and summarize NH student interests in the field of nutrition and dietetics; 2) Identify and contextualize factors that support and prohibit achievement of academic goals and aspirations; 3) Identify NH students' responsibility to the community; 4) Explore the context around NH alumni enrollment in nutrition and dietetics and their perceived impact of RDNs in the community; 5) Identify and describe supporting agencies that foster academic and professional success. DESIGN: This exploratory mixed-methods cross-sectional study surveyed all levels of NH nutrition and dietetics students in the University of Hawai'i (UH) System. In addition, in-depth interviews were conducted with NH students, NH alumni, and supporting agencies to identify supports and barriers, explore the context of NH enrollment in nutrition and dietetics, and the contribution of dietetics to the NH community. PARTICIPANTS/SETTING: Eighty-one NH students enrolled in a nutrition course across the UH system were surveyed. Nine of the 81 NH students surveyed, eight NH alumni, and persons from 15 identified supporting agencies were interviewed. ANALYSIS: Survey responses were descriptively analyzed. Open-ended survey questions and interviews were analyzed through content analysis. To ensure findings were guided by NH perspective, data were triangulated by researchers and a NH dietetics advisory council. RESULTS: Food and chronic disease prevention and management were topics that drew NH students to the field. Bridge/scholarship programs supported NH academic achievement. Education-related cost was a perceived barrier. Alumni and students shared varying degrees of responsibility to serve the NH community. Increasing the connection between NH values and the nutrition and dietetics curriculum are an identified need. CONCLUSION: Findings illuminate opportunities to drive future programmatic efforts. The framework used in this study should be adaptable to other programs to support overall dietetics diversity initiatives.

Dysfunctional purinergic signaling correlates with disease severity in COVID-19 patients.

Ectonucleotidases modulate inflammatory responses by balancing extracellular ATP and adenosine (ADO) and might be involved in COVID-19 immunopathogenesis. Here, we explored the contribution of extracellular nucleotide metabolism to COVID-19 severity in mild and severe cases of the disease. We verified that the gene expression of ectonucleotidases is reduced in the whole blood of patients with COVID-19 and is negatively correlated to levels of CRP, an inflammatory marker of disease severity. In line with these findings, COVID-19 patients present higher ATP levels in plasma and reduced levels of ADO when compared to healthy controls. Cell type-specific analysis revealed higher frequencies of CD39+ T cells in severely ill patients, while CD4+ and CD8+ expressing CD73 are reduced in this same group. The frequency of B cells CD39+CD73+ is also decreased during acute COVID-19. Interestingly, B cells from COVID-19 patients showed a reduced capacity to hydrolyze ATP into ADP and ADO. Furthermore, impaired expression of ADO receptors and a compromised activation of its signaling pathway is observed in COVID-19 patients. The presence of ADO in vitro, however, suppressed inflammatory responses triggered in patients' cells. In summary, our findings support the idea that alterations in the metabolism of extracellular purines contribute to immune dysregulation during COVID-19, possibly favoring disease severity, and suggest that ADO may be a therapeutic approach for the disease.

Self-Sovereign Identity: A Systematic Review, Mapping and Taxonomy.

Self-Sovereign Identity (SSI) is an identity model centered on the user. The user maintains and controls their data in this model. When a service provider requests data from the user, the user sends it directly to the service provider, bypassing third-party intermediaries. Thus, SSI reduces identity providers' involvement in the identification, authentication, and authorization, thereby increasing user privacy. Additionally, users can share portions of their personal information with service providers, significantly improving user privacy. This identity model has drawn the attention of researchers and organizations worldwide, resulting in an increase in both scientific and non-scientific literature on the subject. This study conducts a comprehensive and rigorous systematic review of the literature and a systematic mapping of theoretical and practical advances in SSI. We identified and analyzed evidence from reviewed materials to address four research questions, resulting in a novel SSI taxonomy used to categorize and review publications. Additionally, open challenges are discussed along with recommendations for future work.

Movement Velocity as a Determinant of Actual Intensity in Resistance Exercise.

This study aimed to analyze the acute mechanical, metabolic and EMG response to five resistance exercise protocols (REP) in the full squat (SQ) exercise performed with two velocity conditions: maximal intended velocity (MaxV) vs. half-maximal velocity (HalfV). Eleven resistance-trained men performed 10 REP (5 with each velocity conditions) in random order (72-96 h apart). The REP consisted of three sets of 8-3 repetitions against 45-65% 1RM. The percent change in countermovement jump (CMJ) height, velocity attained with the load that elicited a ~1.00 m·s-1 (V1-load), surface EMG variables and blood lactate concentration were assessed pre- vs. post-exercise protocols. MaxV resulted in greater percent changes (Δ: 12-25%) and intra-condition effect sizes (ES: 0.76-4.84) in loss of V1-load and CMJ height compared to HalfV (Δ: 10-16%; ES: 0.65-3.90) following all REP. In addition, MaxV showed higher post-exercise lactate concentration than HalfV (ES: 0.46-0.83; p<0.05). For EMG variables, only the Dimitrov index resulted in relevant changes after each REP, with MaxV showing greater magnitude of changes (23-38%) than HalfV (12-25%) across all REP. These results suggest that voluntary movement velocity is a key aspect to consider since it clearly determines the overall training intensity during resistance exercise.

Changes in Muscle Strength, Jump, and Sprint Performance in Young Elite Basketball Players: The Impact of Combined High-Speed Resistance Training and Plyometrics.

ABSTRACT: Yáñez-García, JM, Rodríguez-Rosell, D, Mora-Custodio, R, and González-Badillo, JJ. Changes in muscle strength, jump, and sprint performance in young elite basketball players: the impact of combined high-speed resistance training and plyometrics. J Strength Cond Res 36(2): 478-485, 2022-This study aimed to compare the effect of a combined resistance training (RT) and plyometrics on strength, sprint, and jump performance in basketball players of different ages. Thirty three elite basketball players from the same academy were categorized into 3 groups by chronological age: under-13 (U13, n = 11); under-15 (U15, n = 11); and under-17 (U17, n = 11). Players participated in a 6-week strength training program that included 2 sessions each week and consisted of full squats with low loads (45-60% 1 repetition maximum) and low volume (2-3 sets and 4-8 repetitions), jumps, and sprint exercises. All repetitions were performed at maximal intended velocity. In addition to strength training sessions, subjects performed 4 on court basketball training sessions plus 2 official matches per week. After training program, all 3 experimental groups resulted in significant improvements (p < 0.05-0.001) in maximal strength (Δ: 9.2-27.3%; effect size [ES]: 0.38-0.82), countermovement jump height (Δ: 6.6-11.6%; ES: 0.37-0.95), and sprint time in 10 and 20 m (Δ: -3.9 to -0.3%; ES: 0.09-0.69) for all experimental groups. Comparison between groups showed that training program was more effective in inducing improvements in most variables assessed for U13 compared with U15 (ES: 0.11-0.42) and U17 (ES: 0.20-0.43), whereas differences between U15 and U17 were relevant in jump and strength parameters (ES: 0.20-0.35). Therefore, these findings suggest that high-speed RT combined with plyometrics produces increments in several important variables, including strength, jump, and sprint, to yield high performance during a match in young basketball players. However, training program used seems to be generally less effective as the age of the basketball players increased.

Effects of Different Loading Conditions During Resisted Sprint Training on Sprint Performance.

ABSTRACT: Rodríguez-Rosell, D, Sáez de Villarreal, E, Mora-Custodio, R, Asián-Clemente, JA, Bachero-Mena, B, Loturco, I, and Pareja-Blanco, F. Effects of different loading conditions during resisted sprint training on sprint performance. J Strength Cond Res 36(10): 2725-2732, 2022-The aim of this study was to compare the effects of 5 loading conditions (0, 20, 40, 60, and 80% of body mass [BM]) during weighted sled sprint training on unresisted and resisted sprint performance and jump ability. Sixty physically active men were randomly assigned into 5 groups according to the overload used during sled sprint training: 0% (G0%, n = 12), 20% (G20%, n = 12), 40% (G40%, n = 12), 60% (G60%, n = 12), and 80% BM (G80%, n = 12). Pretraining and post-training assessments included: countermovement jump (CMJ), 30-m sprint without extra load, and 20-m sprint with 20, 40, 60, and 80% BM. All 5 experimental groups trained once a week for a period of 8 weeks completing the same training program (number of sessions, number of bouts, running distance in each sprint, rest intervals between repetitions, and total running distance), but with different sled loads (0, 20, 40, 60, and 80% BM). There was a significant "time × group" interaction for resisted sprint performance at 80% BM condition, where the G40% group attained improvements in performance and G80% worsened. Moreover, G40% increased performance in unresisted and the rest of loading conditions. In addition, G0% and G60% showed statistically significant increases in unresisted sprint performance. No relevant changes were observed in the other experimental groups. All groups showed significant improvements ( p < 0.05-0.001) in CMJ height. Therefore, our findings suggest that resisted sprint training with moderate loads (i.e., 40% BM) may have a positive effect on unresisted and resisted sprint performance.

Steganographic Analysis of Blockchains.

Steganography is one of the ways to hide data between parties. Its use can be worrisome, e.g., to hide illegal communications. Researchers found that public blockchains can be an attractive place to hide communications; however, there is not much evidence of actual use in blockchains. Besides, previous work showed a lack of steganalysis methods for blockchains. In this context, we present a steganalysis approach for blockchains, evaluating it in Bitcoin and Ethereum, both popular cryptocurrencies. The main objective is to answer if one can find steganography in real case scenarios, focusing on LSB of addresses and nonces. Our sequential analysis included 253 GiB and 107 GiB of bitcoin and ethereum, respectively. We also analyzed up to 98 million bitcoin clusters. We found that bitcoin clusters could carry up to 360 KiB of hidden data if used for such a purpose. We have not found any concrete evidence of hidden data in the blockchains. The sequential analysis may not capture the perspective of the users of the blockchain network. In this case, we recommend clustering analysis, but it depends on the clustering method's accuracy. Steganalysis is an essential aspect of blockchain security.

Effect of velocity loss during squat training on neuromuscular performance.

This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in strength, vertical jump, sprint performance, and EMG variables. Thirty-three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity-based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55-70% 1RM), frequency (2 sessions/week), number of sets (3), and inter-set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre- and post-training. All groups showed significant (VL10%: 6.4-58.6%; VL30%: 4.5-66.2%; VL45%: 1.8-52.1%; p < 0.05-0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: -2.4%; VL30%: -1.8%; and VL45%: -0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55-70% 1RM characterized by a low-velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports-related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.

Linear programming produces greater, earlier and uninterrupted neuromuscular and functional adaptations than daily-undulating programming after velocity-based resistance training.

This study aimed to compare the effect of linear (LP) and daily-undulating (DUP) programming models on neuromuscular and functional performance using the velocity-based resistance training (VBRT) approach. Thirty-two resistance trained men were randomly assigned into 2 groups: LP (n = 16) or DUP (n = 16). Both training groups completed an 8-week VBRT intervention using the full squat exercise, only differing in the relative intensity (% 1RM) distribution during the training program. Changes produced by each periodization model were evaluated using the following variables: estimated 1RM; average mean propulsive velocity (MPV) attained for all absolute loads common to Pre-test and Post-test; average MPV attained against absolute loads lifted faster than 1 m•s-1; average MPV attained against absolute loads lifted slower than 1 m•s - 1; countermovement jump (CMJ) and fatigue test. Moreover, CMJ and 1RM parameters were evaluated weekly to analyze their evolution along the training program. LP and DUP strategies significantly improved all performance variables analyzed (p<0.001), except the fatigue test in the DUP group. Significant "time x group" interactions were observed in all strength variables and fatigue test in favour of the LP group. In addition, pre-post effect size (ES), percentages of change and weekly comparisons showed higher improvements in the LP group (ES=0.54-2.49, ∆=9.5-60.4%) compared to DUP (ES=0.40-1.65, ∆=5.5-27.2%). Based on these findings, the LP appears to stand as a more effective strategy than DUP to achieve greater, earlier and uninterrupted neuromuscular and functional adaptations in VBRT interventions.

Effects of Unloaded Sprint and Heavy Sled Training on Sprint Performance in Physically Active Women.

PURPOSE: This study aimed to compare the effects of unresisted versus heavy sled sprint training (0% vs 40% body mass [BM]) on sprint performance in women. Moreover, the effects of the aforementioned loads on resisted sprint and jump performance were analyzed. METHODS: Twenty-eight physically active women were randomly allocated into 2 groups: unloaded sprint training group (G0%, n = 14), and resisted sprint training with 40% BM group (G40%, n = 14). Pretraining and posttraining assessments included countermovement jump, unloaded 30-m sprint, and 20-m sprint with 20%, 40%, 60%, and 80% BM. Times to cover 0 to 10 (T10), 0 to 20 (T20), 0 to 30 (T30), 10 to 20 (T10-20), 20 to 30 (T20-30), and 10 to 30 m (T10-30) were recorded. Both groups were trained once a week for 8 weeks and completed the same training program, but with different loads (0% vs 40% BM). RESULTS: No significant time × group interactions were observed. For unloaded sprint performance, G0% showed significant (P = .027) decreases only in T10-20, while G40% attained significant decreases in T30 (P = .021), T10-30 (P = .015), and T20-30 (P = .003). Regarding resisted sprint performance, G0% showed significant (P = .010) improvements only for the 20% BM condition. The G40% group attained significant improvements in all loading conditions (20%, 40%, 60%, and 80% BM). Both groups showed significant improvements (P < .001) in countermovement jump height. CONCLUSIONS: In physically active women, no significant differences in sprint and countermovement jump performance were detected after 8 weeks of resisted and unresisted sprint training programs. Future studies should, therefore, be devoted to how sprint training should be individualized to maximize performance.

Role of the Effort Index in Predicting Neuromuscular Fatigue During Resistance Exercises.

Rodríguez-Rosell, D, Yáñez-García, JM, Mora-Custodio, R, Torres-Torrelo, J, Ribas-Serna, J, and González-Badillo, JJ. Role of the effort index in predicting neuromuscular fatigue during resistance exercises. J Strength Cond Res XX(X): 000-000, 2020-This study aimed: (a) to analyze the acute mechanical, metabolic, and electromyographic (EMG) response to 16 resistance exercise protocols (REPs) defined by the first repetition's mean velocity and the percentage of velocity loss (%VL) over the set in the full-squat (SQ) exercise; and (b) to assess whether the effort index (EI, the product of the first repetition's mean velocity and the %VL in the set) could be used as an objective indicator of neuromuscular fatigue. Eleven resistance-trained men performed 16 REPs in the SQ exercise. For the configuration of the 16 REPs, 4 relative intensities (50, 60, 70, and 80% 1 repetition maximum) and 4 magnitudes of %VL (∼10, ∼20, ∼30, and ∼45%) were used. The induced fatigue after each REP was quantified using the percentage of change in (a) countermovement jump (CMJ) height, (b) mean propulsive velocity attained with the load that elicited an ∼1.00 m·s (V1 m·s load), and (c) changes in surface EMG variables. Blood lactate concentration was also collected. The EI presented very strong relationships with the %VL with the V1 m·s load, CMJ height, and post-exercise lactate concentration (r = 0.92, 0.93, and 0.91, respectively; p < 0.001). Moderate to strong relationships were found between the EI and the changes in amplitude (r = 054-0.58; p < 0.05), frequency (r = -0.55 to -0.83; p < 0.05-0.001), and time-frequency (r = 0.52-0.77; p < 0.05-0.001) EMG variables. In addition, the moderate to strong relationships found between the relative changes in mechanical, metabolic, and EMG variables after each REP reinforce the validity of the EI as an objective indicator of muscle fatigue, metabolic stress, and neural effect induced by typical resistance training sessions. Thus, by adjusting the EI in each session, it is possible to quantifying the actual level of effort experienced by each individual during resistance exercises.

Allergen-Specific Immunotherapy With Liposome Containing CpG-ODN in Murine Model of Asthma Relies on MyD88 Signaling in Dendritic Cells.

Changing the immune responses to allergens is the cornerstone of allergen immunotherapy. Allergen-specific immunotherapy that consists of repeated administration of increasing doses of allergen extract is potentially curative. The major inconveniences of allergen-specific immunotherapy include failure to modify immune responses, long-term treatment leading to non-compliance and the potential for developing life-threating anaphylaxis. Here we investigated the effect of a novel liposomal formulation carrying low dose of allergen combined with CpG-ODN, a synthetic TLR9 agonist, on established allergic lung inflammation. We found that challenge with allergen (OVA) encapsulated in cationic liposome induced significantly less severe cutaneous anaphylactic reaction. Notably, short-term treatment (three doses) with a liposomal formulation containing co-encapsulated allergen plus CpG-ODN, but not allergen or CpG-ODN alone, reversed an established allergic lung inflammation and provided long-term protection. This liposomal formulation was also effective against allergens derived from Blomia tropicalis mite extract. The attenuation of allergic inflammation was not associated with increased numbers of Foxp3-positive or IL-10-producing regulatory T cells or with increased levels of IFN-gamma in the lungs. Instead, the anti-allergic effect of the liposomal formulation was dependent of the innate immune signal transduction generated in CD11c-positive putative dendritic cells expressing MyD88 molecule. Therefore, we highlight the pivotal role of dendritic cells in mediating the attenuation of established allergic lung inflammation following immunotherapy with a liposomal formulation containing allergen plus CpG-ODN.

Velocity-based resistance training: impact of velocity loss in the set on neuromuscular performance and hormonal response.

This study aimed to compare the effects of 2 resistance training (RT) programs with different velocity losses (VLs) allowed in each set: 10% (VL10%) versus 30% (VL30%) on neuromuscular performance and hormonal response. Twenty-five young healthy males were randomly assigned into 2 groups: VL10% (n = 12) or VL30% (n = 13). Subjects followed a velocity-based RT program for 8 weeks (2 sessions per week) using only the full-squat (SQ) exercise at 70%-85% 1-repetition maximum (1RM). Repetition velocity was recorded in all training sessions. A 20-m running sprint, countermovement jump (CMJ), 1RM, muscle endurance, and electromyogram (EMG) during SQ exercise and resting hormonal concentrations were assessed before and after the RT program. Both groups showed similar improvements in muscle strength and endurance variables (VL10%: 7.0%-74.8%; VL30%: 4.2%-73.2%). The VL10% resulted in greater percentage increments in CMJ (9.2% vs. 5.4%) and sprint performance (-1.5% vs. 0.4%) than VL30%, despite VL10% performing less than half of the repetitions than VL30% during RT. In addition, only VL10% showed slight increments in EMG variables, whereas no significant changes in resting hormonal concentrations were observed. Therefore, our results suggest that velocity losses in the set as low as 10% are enough to achieve significant improvements in neuromuscular performance, which means greater efficiency during RT. Novelty The VL10% group showed similar or even greater percentage of changes in physical performance compared with VL30%. No significant changes in resting hormonal concentrations were observed for any training group. Curvilinear relationships between percentage VL in the set and changes in strength and CMJ performance were observed.

Relationship Between Velocity Loss and Repetitions in Reserve in the Bench Press and Back Squat Exercises.

Rodríguez-Rosell, D, Yáñez-García, JM, Sánchez-Medina, L, Mora-Custodio, R, and González-Badillo, JJ. Relationship between velocity loss and repetitions in reserve in the bench press and back squat exercises. J Strength Cond Res 34(9): 2537-2547, 2020-This study aimed to compare the pattern of repetition velocity decline during a single set to failure performed against 4 relative loads in the bench press (BP) and full back squat (SQ) exercises. After an initial test to determine 1 repetition maximum (1RM) strength and load-velocity relationships, 20 men performed one set of repetitions to failure (MNR test) against loads of 50, 60, 70, and 80% 1RM in BP and SQ, on 8 random order sessions performed every 6-7 days. Velocity against the load that elicited a ∼1.00 m·s (V1 m·s load) was measured before and immediately after each MNR test, and it was considered a measure of acute muscle fatigue. The number of repetitions completed against each relative load showed high interindividual variability in both BP (coefficient of variation [CV]: 15-22%) and SQ (CV: 26-34%). Strong relationships were found between the relative loss of velocity in the set and the percentage of performed repetitions in both exercises (R = 0.97 and 0.93 for BP and SQ, respectively). Equations to predict repetitions left in reserve from velocity loss are provided. For a given magnitude of velocity loss within the set (15-65%), the percentages of performed repetitions were lower for the BP compared with the SQ for all loads analyzed. Acute fatigue after each set to failure was found dependent on the magnitude of velocity loss (r = 0.97 and 0.99 for BP and SQ, respectively) but independent of the number of repetitions completed by each participant (p > 0.05) for both exercises. The percentage of velocity loss against the V1 m·s load decreased as relative load increased, being greater for BP than SQ. These findings indicate that monitoring repetition velocity can be used to provide a very good estimate of the number (or percentage) of repetitions actually performed and those left in reserve in each exercise set, and thus to more objectively quantify the level of effort incurred during resistance training.

Time Course of Recovery From Resistance Exercise With Different Set Configurations.

Pareja-Blanco, F, Rodríguez-Rosell, D, Aagaard, P, Sánchez-Medina, L, Ribas-Serna, J, Mora-Custodio, R, Otero-Esquina, C, Yáñez-García, JM, and González-Badillo, JJ. Time course of recovery from resistance exercise with different set configurations. J Strength Cond Res 34(10): 2867-2876, 2020-This study analyzed the response to 10 resistance exercise protocols differing in the number of repetitions performed in each set (R) with respect to the maximum predicted number (P). Ten males performed 10 protocols (R(P): 6(12), 12(12), 5(10), 10(10), 4(8), 8(8), 3(6), 6(6), 2(4), and 4(4)). Three sets with 5-minute interset rests were performed in each protocol in bench press and squat. Mechanical muscle function (countermovement jump height and velocity against a 1 m·s load, V1-load) and biochemical plasma profile (testosterone, cortisol, growth hormone, prolactin, IGF-1, and creatine kinase) were assessed at several time points from 24-hour pre-exercise to 48-hour post-exercise. Protocols to failure, especially those in which the number of repetitions performed was high, resulted in larger reductions in mechanical muscle function, which remained reduced up to 48-hour post-exercise. Protocols to failure also showed greater increments in plasma growth hormone, IGF-1, prolactin, and creatine kinase concentrations. In conclusion, resistance exercise to failure resulted in greater fatigue accumulation and slower rates of neuromuscular recovery, as well as higher hormonal responses and greater muscle damage, especially when the maximal number of repetitions in the set was high.

Dendritic Cells Expressing MyD88 Molecule Are Necessary and Sufficient for CpG-Mediated Inhibition of IgE Production In Vivo.

Elevated levels of immunoglobulin E (IgE) are associated with allergies and other immunological disorders. Sensitization with alum adjuvant favours IgE production while CpG-ODN adjuvant, a synthetic toll-like receptor 9 (TLR9) agonist, inhibits it. The cellular mechanisms underlying in vivo TLR regulation of immunoglobulin production, specially IgE, are still controversial. Specifically, TLR-mediated IgE regulation in vivo is not yet known. In this study we showed that augmented levels of IgE induced by sensitizations to OVA with or without alum adjuvant or with OVA-pulsed dendritic cells (DCs) were inhibited by co-administration of CpG. Notably, CpG-mediated suppression of IgE production required MyD88-expression on DCs but not on B-cells. This finding contrasts with previous in vitro studies reporting regulation of IgE by a direct action of CpG on B cells via MyD88 pathway. In addition, we showed that CpG also inhibited IgE production in a MyD88-dependent manner when sensitization was performed with OVA-pulsed DCs. Finally, CpG signalling through MyD88 pathway was also necessary and sufficient to prevent anaphylactic antibody production involved in active cutaneous anaphylaxis.

TLR9 agonist adsorbed to alum adjuvant prevents asthma-like responses induced by Blomia tropicalis mite extract.

Blomia tropicalis mite is highly prevalent in tropical and subtropical regions and it is associated with allergic diseases such as rhinitis and asthma. By using an OVA-model of allergic lung disease, we have previously shown that sensitization in the presence of toll like receptors (TLRs) agonists attenuates subsequent OVA-induced allergic responses. Here, we evaluated the effect of CpG-ODN, a specific synthetic TLR-9 agonist, on the development of experimental asthma induced by Blomia tropicalis extract, a relevant source of aeroallergens. Among different protocols of Blomia tropicalis extract sensitization, the subcutaneous sensitization in the presence of alum adjuvant induced the highest Th2 responses, including high IgE levels. Adsorption of CpG to Blomia tropicalis extract/Alum attenuated the airway hyperreactivity, the infiltration of inflammatory cells including eosinophils, and the IL-5 content in BAL. In addition, lung peribronchial inflammatory infiltrate, mucus production and IL-5-producing CD3+ CD4+ T cells were significantly reduced in the Blomia tropicalis extract/Alum+CpG group. Importantly, CpG inhibited total IgE production as well as active systemic or cutaneous anaphylaxis reactions. Inhibition of pulmonary Th2 responses was associated with increased IL-10 production but not with IFN-γ production. Notably, in IL-10-deficient mice, sensitization with OVA/Alum+CpG resulted in intense lung neutrophilia and IFN-γ production, indicating that IL-10 is necessary to inhibit subsequent Th1 immunity. Our work highlights the mechanisms of allergy attenuation by CpG and it indicates the potential use of Alum-based formulation with CpG to treat allergic processes.