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Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke

This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.

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ZáNean McClain, Jill Pawlowski, and Daniel W. Tindall

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Annemiek J. Roete, Marije T. Elferink-Gemser, Ruby T.A. Otter, Inge K. Stoter, and Robert P. Lamberts

Purpose: The aim of this brief review was to present an overview of noninvasive markers in trained to professional endurance athletes that can reflect a state of functional overreaching. Methods: A systematic literature search was conducted in the PubMed, Scopus, and PsycINFO databases. After screening 380 articles, 12 research papers were included for the systematic review. Results: Good consensus was found between the different papers in which noninvasive parameters were able to reflect a state of functional overreaching. Changes in power output (PO), heart rate (HR; [sub]maximal and HR recovery), rating of perceived exertion, and scores in the Daily Analysis of Life Demands for Athletes (DALDA) and/or Profile of Mood States (POMS) were shown to be able to reflect functional overreaching, whereas changes in maximal oxygen uptake and HR-variability parameters were not. Conclusion: Functional overreaching within a maximal performance test was characterized by a decrease in peak PO and a lower maximum HR, whereas a lower mean PO and a lower HR were observed during time trials. Changes in parameters during a standardized submaximal test when functionally overreached were characterized by a higher PO at a fixed HR or a lower HR at a fixed intensity, higher rating of perceived exertion, and a faster HR recovery. Although both the DALDA and POMS were able to reflect functional overreaching, the POMS was not able to differentiate this response from acute fatigue, which makes it unsuitable for accurately monitoring functional overreaching.

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Michelle T. Barrack, Marta D. Van Loan, Mitchell Rauh, and Jeanne F. Nichols

This prospective study evaluated the 3-year change in menstrual function and bone mass among 40 female adolescent endurance runners (age 15.9 ± 1.0 years) according to baseline disordered eating status. Three years after initial data collection, runners underwent follow-up measures including the Eating Disorder Examination Questionnaire and a survey evaluating menstrual function, running training, injury history, and prior sports participation. Dual-energy X-ray absorptiometry was used to measure bone mineral density and body composition. Runners with a weight concern, shape concern, or global score ≥4.0 or reporting >1 pathologic behavior in the past 28 days were classified with disordered eating. Compared with runners with normal Eating Disorder Examination Questionnaire scores at baseline, runners with disordered eating at baseline reported fewer menstrual cycles/year (6.4 ± 4.5 vs. 10.5 ± 2.8, p = .005), more years of amenorrhea (1.6 ± 1.4 vs. 0.3 ± 0.5, p = .03), and a higher proportion of menstrual irregularity (75.0% vs. 31.3%, p = .02) and failed to increase lumbar spine or total hip bone mineral density at the 3-year follow-up. In a multivariate model including body mass index and menstrual cycles in the past year at baseline, baseline shape concern score (B = −0.57, p value = .001) was inversely related to the annual number of menstrual cycles between assessments. Weight concern score (B = −0.40, p value = .005) was inversely associated with lumbar spine bone mineral density Z-score change between assessments according to a multivariate model adjusting for age and body mass index. These finding support associations between disordered eating at baseline and future menstrual irregularities or reduced accrual of lumbar spine bone mass in female adolescent endurance runners.

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Gabriel Perri Esteves, Paul Swinton, Craig Sale, Ruth M. James, Guilherme Giannini Artioli, Hamilton Roschel, Bruno Gualano, Bryan Saunders, and Eimear Dolan

Currently, little is known about the extent of interindividual variability in response to beta-alanine (BA) supplementation, nor what proportion of said variability can be attributed to external factors or to the intervention itself (intervention response). To investigate this, individual participant data on the effect of BA supplementation on a high-intensity cycling capacity test (CCT110%) were meta-analyzed. Changes in time to exhaustion (TTE) and muscle carnosine were the primary and secondary outcomes. Multilevel distributional Bayesian models were used to estimate the mean and SD of BA and placebo group change scores. The relative sizes of group SDs were used to infer whether observed variation in change scores were due to intervention or non-intervention-related effects. Six eligible studies were identified, and individual data were obtained from four of these. Analyses showed a group effect of BA supplementation on TTE (7.7, 95% credible interval [CrI] [1.3, 14.3] s) and muscle carnosine (18.1, 95% CrI [14.5, 21.9] mmol/kg DM). A large intervention response variation was identified for muscle carnosine (σIR = 5.8, 95% CrI [4.2, 7.4] mmol/kg DM) while equivalent change score SDs were shown for TTE in both the placebo (16.1, 95% CrI [13.0, 21.3] s) and BA (15.9, 95% CrI [13.0, 20.0] s) conditions, with the probability that SD was greater in placebo being 0.64. In conclusion, the similarity in observed change score SDs between groups for TTE indicates the source of variation is common to both groups, and therefore unrelated to the supplement itself, likely originating instead from external factors such as nutritional intake, sleep patterns, or training status.

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Elliott C.R. Hall, Sandro S. Almeida, Shane M. Heffernan, Sarah J. Lockey, Adam J. Herbert, Peter Callus, Stephen H. Day, Charles R. Pedlar, Courtney Kipps, Malcolm Collins, Yannis P. Pitsiladis, Mark A. Bennett, Liam P. Kilduff, Georgina K. Stebbings, Robert M. Erskine, and Alun G. Williams

Purpose: Genetic polymorphisms have been associated with the adaptation to training in maximal oxygen uptake (V˙O2max). However, the genotype distribution of selected polymorphisms in athletic cohorts is unknown, with their influence on performance characteristics also undetermined. This study investigated whether the genotype distributions of 3 polymorphisms previously associated with V˙O2max training adaptation are associated with elite athlete status and performance characteristics in runners and rugby athletes, competitors for whom aerobic metabolism is important. Methods: Genomic DNA was collected from 732 men including 165 long-distance runners, 212 elite rugby union athletes, and 355 nonathletes. Genotype and allele frequencies of PRDM1 rs10499043 C/T, GRIN3A rs1535628 G/A, and KCNH8 rs4973706 T/C were compared between athletes and nonathletes. Personal-best marathon times in runners, as well as in-game performance variables and playing position, of rugby athletes were analyzed according to genotype. Results: Runners with PRDM1 T alleles recorded marathon times ∼3 minutes faster than CC homozygotes (02:27:55 [00:07:32] h vs 02:31:03 [00:08:24] h, P = .023). Rugby athletes had 1.57 times greater odds of possessing the KCNH8 TT genotype than nonathletes (65.5% vs 54.7%, χ 2 = 6.494, P = .013). No other associations were identified. Conclusions: This study is the first to demonstrate that polymorphisms previously associated with V˙O2max training adaptations in nonathletes are also associated with marathon performance (PRDM1) and elite rugby union status (KCNH8). The genotypes and alleles previously associated with superior endurance-training adaptation appear to be advantageous in long-distance running and achieving elite status in rugby union.

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Alexandru Nicolae Ungureanu, Corrado Lupo, Gennaro Boccia, and Paolo Riccardo Brustio

Purpose: The primary aim of this study was to evaluate whether the internal (session rating of perceived exertion [sRPE] and Edwards heart-rate-based method) and external training load (jumps) affect the presession well-being perception on the day after (ie, +22 h), according to age and tactical position, in elite (ie, Serie A2) female volleyball training. Methods: Ten female elite volleyball players (age = 23 [4] y, height = 1.82 [0.04] m, body mass = 73.2 [4.9] kg) had their heart rate monitored during 13 team (115 individual) training sessions (duration: 101 [8] min). Mixed-effect models were applied to evaluate whether sRPE, Edwards method, and jumps were correlated (P ≤ .05) to Hooper index factors (ie, perceived sleep quality/disorders, stress level, fatigue, and delayed-onset muscle soreness) in relation to age and tactical position (ie, hitters, central blockers, opposites, and setters). Results: The results showed a direct relationship between sRPE (P < .001) and presession well-being perception 22 hours apart, whereas the relationship was the inverse for Edwards method internal training load. Age, as well as the performed jumps, did not affect the well-being perception of the day after. Finally, central blockers experienced a higher delayed-onset muscle soreness than hitters (P = .003). Conclusions: Findings indicated that female volleyball players’ internal training load influences the pretraining well-being status on the day after (+ 22 h). Therefore, coaches can benefit from this information to accurately implement periodization in a short-term perspective and to properly adopt recovery strategies in relation to the players’ well-being status.

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Christian J. Cook, Blair T. Crewther, Liam P. Kilduff, Linda L. Agnew, Phillip Fourie, and Benjamin G. Serpell

Purpose: To establish if training volume was associated with androgen baselines and androgen responsiveness to acute exercise. Methods: During a “high-volume” training phase, 28 cyclists (14 men and 14 women) undertook oxygen-uptake and maximal-work-capacity testing. Two days later, they completed a repeat-sprint protocol, which was repeated 3 weeks later during a “low-volume” phase. Blood and saliva samples were collected before and after (+5 and +60 min) the repeat-sprint protocol. Blood was assayed for total testosterone (TT), free testosterone (FT), and dihydrotestosterone (DHT) and saliva, for testosterone and DHT. Results: Pretrial TT, FT, and DHT concentration was greater for males (P < .001, large effect size differences), and in both genders TT, DHT, and saliva for DHT was higher during high-volume loading (moderate to large effect size). Area-under-the-curve analysis revealed larger TT, FT, and DHT responses to the repeat-sprint protocol among females, and high-volume training was linked to larger TT, DHT, and saliva for DHT responses (moderate to large effect size). Baseline TT and FT correlated with oxygen uptake and work capacity in both genders (P < .05). Conclusion: DHT showed no acute performance correlation but was responsive to volume of training, particularly in females. This work informs on timelines and relationships of androgenic biomarkers in males and females across different training loads, adding to the complexity that should be considered in interpretation thereof. The authors speculate that testosterone may impact acute performance via behavioral mechanisms of motivation and attention; DHT, via training volume-induced androgenic promotion, may facilitate long-term adaptive changes, especially for females.