Purpose: To assess the impact of microcycle (MC) structures on physical and technical performances in rugby league training and matches. Methods: Thirty-four professional rugby league players were monitored during all training sessions and matches across a single season wherein 2 different competition-phase MC structures were implemented. The first MC structure involved the first session on match day (MD) + 2 and the main stimulus delivered MD − 3, and the second structure delayed all sessions by 1 day (first session on MD + 3 and main session MD − 2; MC structure in the second half of the season). Physical output was quantified via relative total speed (in meters per minute), high-speed running (per minute; ≥4.0 m·s−1), and very-high-speed running (per minute; ≥5.5 m·s−1), measured using a global positioning system (10 Hz) in addition to accelerometer (100 Hz) metrics (PlayerLoad per minute and PlayerLoadslow per minute]) during training and matches. Technical performance (number of runs, meters gained, tackles made and missed) was recorded during matches. Generalized linear mixed models and equivalence tests were used to identify the impact of MC structure on physical and technical output. Results: Nonequivalent increases in meters per minute, high-speed running per minute, and PlayerLoad per minute were observed for the first training stimulus in MC structure in the second half of the season with no practical difference in midcycle sessions observed. The MC structure in the second half of the season structure resulted in increased high-speed running per minute and decreased PlayerLoadslow per minute during MD with no differences observed in technical performance. Conclusions: Delaying the first training stimulus of the MC allowed for greater training load accumulation without negative consequences in selected match running and technical performance measures. This increased MC load may support the maintenance of physical capacities across the in-season.
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Tahleya Eggers, Rebecca Cross, Dean Norris, Lachlan Wilmot, and Ric Lovell
Alannah K.A. McKay, Peter Peeling, Martyn J. Binnie, Paul S.R. Goods, Marc Sim, Rebecca Cross, and Jason Siegler
Purpose: To assess the efficacy of a topical sodium bicarbonate (0.3 g/kg body weight NaHCO3) application (PR lotion; Amp Human) on blood buffering capacity and performance in recreationally active participants (study A) and moderately trained athletes (study B). Methods: In Study A, 10 participants completed 2 experimental trials: oral NaHCO3 (0.3 g/kg body weight + placebo lotion) or PR lotion (0.9036 g/kg body weight + oral placebo) applied 90 minutes prior to a cycling task to exhaustion (30-s sprints at 120% peak power output with 30-s rest). Capillary blood was collected and analyzed for pH, bicarbonate, and lactate every 10 minutes throughout the 90-minute loading period and postexercise at 5, 10, and 15 minutes. In Study B, 10 cyclists/triathletes completed 2 experimental trials, applying either PR or placebo lotion 30 minutes prior to a cycling performance task (3 × 30-s maximal sprints with 90-s recovery). Capillary blood samples were collected at baseline, preexercise, and postexercise and analyzed as per study A. Results: In Study A, pH and bicarbonate were significantly elevated from baseline after 10 minutes in the oral NaHCO3 condition and throughout recovery compared with no elevation in the PR lotion condition (P < .001). No differences in cycling time occurred between PR lotion (349 [119] s) and oral NaHCO3 (363 [80] s; P = .697). In Study B, no differences in blood parameters, mean power (P = .108), or peak power (P = .448) were observed between conditions. Conclusions: PR lotion was ineffective in altering blood buffering capacity or enhancing performance in either trained or untrained individuals.
Jason C. Siegler, Amelia J. Carr, William T. Jardine, Lilia Convit, Rebecca Cross, Dale Chapman, Louise M. Burke, and Megan Ross
Buffering agents have not been comprehensively profiled in terms of their capacity to influence water retention prior to exercise. The purpose of this investigation was to profile the fluid retention characteristics of sodium bicarbonate (BIC) and sodium citrate (CIT) to determine the efficacy of these buffering mediums as hyperhydrating agents. Nineteen volunteers (13 males and six females; age = 28.3 ± 4.9 years) completed three trials (randomized and cross-over design). For each trial, a baseline measurement of body mass, capillary blood, and urine was collected prior to ingestion of their respective condition (control condition [CON] = 25 ml/kg artificially sweetened water; BIC condition = CON + 7.5 g/L of sodium in the form of BIC; CIT condition = CON + 7.5 g/L of sodium in the form of CIT). The fluid loads were consumed in four equal aliquots (0, 20, 40 and 60 min; fluid intake was 1.972 ± 361 ml [CON]; 1.977 ± 360 ml [BIC]; 1.953 ± 352 ml [CIT]). Samples were recorded at 20 (body mass and urine) and 60 min (blood) intervals for 180 min. Blood buffering capacity (HCO3 −) was elevated (p < .001) in both BIC (32.1 ± 2.2 mmol/L) and CIT (28.9 ± 3.8 mmol/L) at 180 min compared with CON (25.1 ± 1.8 mmol/L). Plasma volume expansion was greater (p < .001) in both BIC (8.1 ± 1.3%) and CIT (5.9 ± 1.8%) compared with CON (−1.1 ± 1.4%); whereas, total urine production was lower in BIC and CIT at 180 min (BIC vs. CON, mean difference of 370 ± 85 ml; p < .001; CIT vs. CON, mean difference of 239 ± 102 ml; p = .05). There were no increases observed in body mass (p = .9). Under resting conditions, these data suggest BIC and CIT induce a greater plasma hypervolemic response as compared with water alone.
