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Hanstock, H., Govus, A., Stenqvist, T. B., Melin, A. K., Sylta, Ø. & Torstveit, M. K. (2020). Influence of Immune and Nutritional Biomarkers on Illness Risk During Interval Training. International Journal of Sports Physiology and Performance, 15(1), 60-67
Open this publication in new window or tab >>Influence of Immune and Nutritional Biomarkers on Illness Risk During Interval Training
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2020 (English)In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 15, no 1, p. 60-67Article in journal (Refereed) Published
Abstract [en]

Intensive training periods may negatively influence immune function, but the immunological consequences of specific high-intensity training (HIT) prescriptions are not well defined. Purpose: This study explored whether three different HIT prescriptions influence multiple health-related biomarkers and whether biomarker responses to HIT were associated with upper respiratory illness (URI) risk. Methods: Twenty-five male cyclists and triathleteswere randomised to three HIT groups and completed twelve HIT sessions over four weeks. Peak oxygen consumption (V̇O2peak) was determined using an incremental cycling protocol, while resting serum biomarkers (cortisol, testosterone, 25(OH)D and ferritin), salivary immunoglobulin-A (s-IgA) and energy availability (EA) were assessed before and after the training intervention. Participants self-reported upper respiratory symptoms during the interventionand episodes of URI were identified retrospectively. Results: Fourteen athletes reported URIs, but there were no differences in incidence, duration or severity between groups. Increased risk of URI was associated with higher s-IgA secretion rates (odds ratio=0.90, 90% CI:0.83-0.97). Lower pre-intervention cortisol and higher EA predicted a 4% increase in URI duration. Participants with higher V̇O2peak reported higher total symptom scores (incidence rate ratio=1.07, 90% CI:1.01-1.13). Conclusions: Although multiple biomarkers wereweakly associated with risk of URI, the direction of associations between s-IgA, cortisol, EA and URI risk were inverse to previous observations and physiological rationale. There was a cluster of URIs within the first week of the training intervention, but no samples were collected at this time-point. Future studies should incorporate more frequent sample time-points, especially around the onset of new training regimes, and include athletes with suspected or known nutritional deficiencies.

Keywords
Endurance athletes, HIT, immunity, training load, URTI
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-36069 (URN)10.1123/ijspp.2018-0527 (DOI)2-s2.0-85077647594 (Scopus ID)
Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2020-01-20Bibliographically approved
Carr, A., McGawley, K., Govus, A., Andersson, E., Shannon, O. M., Mattsson, S. & Melin, A. K. (2019). Nutritional Intake in Elite Cross-Country Skiers During Two Days of Training and Competition. International Journal of Sport Nutrition & Exercise Metabolism, 29(3), 273-281
Open this publication in new window or tab >>Nutritional Intake in Elite Cross-Country Skiers During Two Days of Training and Competition
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2019 (English)In: International Journal of Sport Nutrition & Exercise Metabolism, ISSN 1526-484X, E-ISSN 1543-2742, Vol. 29, no 3, p. 273-281Article in journal (Refereed) Published
Abstract [en]

This study investigated the energy, macronutrient and fluid intakes, as well as hydration status (urine specific gravity; USG), in elite cross-country skiers during a typical day of training (day one) and a sprint skiing competition the following day (day two). Thirty-one (18 male and 13 female) national team skiers recorded their food and fluid intakes and USG was measured on days one and two. In addition, the females completed the Low Energy Availability in Females-Questionnaire (LEAF-Q) to assess their risk of long-term energy deficiency. Energy intake for males was 65+/-9 kcal/kg on day one versus 58+/-9 kcal/kg on day two (P=0.002), and for females was 57+/-10 on day one versus 55+/-5 kcal/kg on day two (P=0.445). Carbohydrate intake recommendations of 10-12 g/kg/day were not met by 89% of males and 92% of females. All males and females had a protein intake above the recommended 1.2-2.0 g/kg on both days, and a post-exercise protein intake above the recommended 0.3 g/kg. Of the females, 31% were classified as being at risk of long-term energy deficiency. In the morning of day one, 50% of males and 46% of females were dehydrated; on day two this was the case for 56% of males and 38% of females. In conclusion, these data suggest that elite cross-country skiers ingested more protein and less carbohydrate than recommended, and one third of the females were considered at risk for long-term energy deficiency. Furthermore, many of the athletes were dehydrated prior to training and competition.

Keywords
Carbohydrate, Energy deficiency, Hydration status, Protein, Winter sports
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-34474 (URN)10.1123/ijsnem.2017-0411 (DOI)000466708800005 ()29989466 (PubMedID)2-s2.0-85065593387 (Scopus ID)
Available from: 2018-09-22 Created: 2018-09-22 Last updated: 2019-07-09Bibliographically approved
Andersson, E., Govus, A., Shannon, O. M. & McGawley, K. (2019). Sex differences in performance and pacing strategies during sprint skiing. Frontiers in Physiology, 10, Article ID 295.
Open this publication in new window or tab >>Sex differences in performance and pacing strategies during sprint skiing
2019 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 295Article in journal (Refereed) Published
Abstract [en]

Purpose: This study aimed to compare performance and pacing strategies between elite male and female cross-country skiers during a sprint competition on snow using the skating technique.

Methods: Twenty male and 14 female skiers completed an individual time-trial prolog (TT) and three head-to-head races (quarter, semi, and final) on the same 1,572-m course, which was divided into flat, uphill and downhill sections. Section-specific speeds, choice of sub-technique (i.e., gear), cycle characteristics, heart rate and post-race blood lactate concentration were monitored. Power output was estimated for the different sections during the TT, while metabolic demand was estimated for two uphill camera sections and the final 50-m flat camera section.

Results: Average speed during the four races was ∼12.5% faster for males than females (P < 0.001), while speeds on the flat, uphill and downhill sections were ∼11, 18, and 9% faster for the males than females (all P< 0.001 for terrain, sex, and interaction). Differences in uphill TT speed between the sexes were associated with different sub-technique preferences, with males using a higher gear more frequently than females (P < 0.05). The estimated metabolic demand relative to maximal oxygen uptake (V&#x2D9;" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; outline: 0px !important;">V˙V˙O2max) was similar for both sexes during the two uphill camera sections (∼129% of V&#x2D9;" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; outline: 0px !important;">V˙V˙O2max) and for the final 50-m flat section (∼153% of V&#x2D9;" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; outline: 0px !important;">V˙V˙O2max). Relative power output during the TT was 18% higher for males compared to females (P < 0.001) and was highly variable along the course for both sexes (coefficient of variation [CV] between sections 4–9 was 53%), while the same variation in heart rate was low (CV was ∼3%). The head-to-head races were ∼2.4% faster than the TT for both sexes and most race winners (61%) were positioned first already after 30 m of the race. No sex differences were observed during any of the races for heart rate or blood lactate concentration.

Conclusion: The average sex difference in sprint skiing performance was ∼12.5%, with varying differences for terrain-specific speeds. Moreover, females skied relatively slower uphill (at a lower gear) and thereby elicited more variation in their speed profiles compared to the males.

Keywords
Cross-country skiing, elite athletes, head-to-head, metabolic demand, power output, time-trial
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-35839 (URN)10.3389/fphys.2019.00295 (DOI)000462046900001 ()30967794 (PubMedID)
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-05-20Bibliographically approved
Govus, A., Andersson, E. P., Shannon, O. M., Provis, H., Karlsson, M. & McGawley, K. (2018). Commercially available compression garments or electrical stimulation do not enhance recovery following a sprint competition in elite cross-country skiers. European Journal of Sport Science, 18(10), 1299-1308
Open this publication in new window or tab >>Commercially available compression garments or electrical stimulation do not enhance recovery following a sprint competition in elite cross-country skiers
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2018 (English)In: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 18, no 10, p. 1299-1308Article in journal (Refereed) Published
Abstract [en]

This study investigated whether commercially available compression garments (COMP) exerting a moderate level of pressureand/or neuromuscular electrical stimulation (NMES) accelerate recovery following a cross-country sprint skiing competitioncompared with a control group (CON) consisting of active recovery only. Twenty-one senior (12 males, 9 females) and 11junior (6 males, 5 females) Swedish national team skiers performed an outdoor sprint skiing competition involving foursprints lasting ∼3–4 min. Before the competition, skiers were matched by sex and skiing level (senior versus junior) andrandomly assigned to COMP (n = 11), NMES (n = 11) or CON (n = 10). Creatine kinase (CK), urea, countermovementjump (CMJ) height, and perceived muscle pain were measured before and 8, 20, 44 and 68 h after competition. NeitherCOMP nor NMES promoted the recovery of blood biomarkers, CMJ or perceived pain post-competition compared withCON (all P > .05). When grouping all 32 participants, urea and perceived muscle pain increased from baseline, peaking at8 h (standardised mean difference (SMD), [95% confidence intervals (CIs)]): 2.8 [2.3, 3.2]) and 44 h (odds ratio [95%CI]: 3.3 [2.1, 5.1]) post-competition, respectively. Additionally, CMJ was lower than baseline 44 and 68 h postcompetitionin both males and females (P < .05). CK increased from baseline in males, peaking at 44 h (SMD: 1.4 [−0.4,0.9]), but was decreased in females at 20 h post-competition (SMD: −0.8 [−1.4, −0.2]). In conclusion, cross-countrysprint skiing induced symptoms of exercise-induced muscle damage peaking 8–44 h post-competition. However, neitherCOMP nor NMES promoted physiological or perceptual recovery compared with CON.

Keywords
Countermovement jump, creatine kinase, muscle damage, performance, urea
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-34475 (URN)10.1080/17461391.2018.1484521 (DOI)000444565000001 ()29924696 (PubMedID)2-s2.0-85048822175 (Scopus ID)
Available from: 2018-09-22 Created: 2018-09-22 Last updated: 2019-01-31Bibliographically approved
Hanstock, H., Govus, A., Stenqvist, T. B., Melin, A., Sylta, Ö. & Torstveit, M. K. (2018). Evaluation of physiological and nutritional risk factors for upper respiratory illness using a zero-inflated negative binomial model. In: Journal of Sports Sciences: Volume 36, 2018 - Issue sup1: BASES Conference 2018 – Programme and Abstracts. Paper presented at BASES Conference 2018, 27-28 November 2018, Harrogate, UK (pp. 44-45). Routledge, 36 (S1)
Open this publication in new window or tab >>Evaluation of physiological and nutritional risk factors for upper respiratory illness using a zero-inflated negative binomial model
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2018 (English)In: Journal of Sports Sciences: Volume 36, 2018 - Issue sup1: BASES Conference 2018 – Programme and Abstracts, Routledge, 2018, Vol. 36 (S1), p. 44-45Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Intensified training periods may increase incidence of upper respiratory illness (URI) in athletes (Meeusen et al., 2013,Medicine and Science in Sports and Exercise, 45(1), 186–205). Many physiological and nutritional risk factors have beenassociated with increased risk of URI (Bermon et al., 2017, Exercise Immunology Review, 23, 8–50), including reductionsin salivary IgA (sIgA), elevated cortisol, vitamin D insufficiency, iron deficiency and low energy availability (EA). However, few studies have explored the relative importance of each of thesehealth-related biomarkers in a multivariate model. Our aimwas therefore to investigate the relationship between multiplebiological risk factors for illness and incidence, duration andseverity of URIs that present during intensified training. 3815Twenty-five well-trained male cyclists and triathletes (age 30 ± 9 y, VO2peak 64 ± mL· kg−1· min−1) performed one ofthree different high-intensity interval training (HIT) programmes for three sessions per week over four weeks in November-December. The study received local ethical approval and participants provided written, informed consentto participate. Participants performed each HIT session at “isoeffort” intensity and sessions were matched for total accumulated work duration. Participants logged upper respiratorysymptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively using the followinga priori criteria: weekly symptom score > 14 or selfreportedcommon cold for > 2 consecutive days (Jacksonet al., 1958, American Medical Association Archives of Internal Medicine, 101, 267–278). Before commencing the training period, VO2peak was determined using an incremental maximal cycling protocol and participants provided rested, fasted blood and saliva samples prior to the training period foranalysis of plasma 25(OH)D, ferritin, cortisol, testosterone and sIgA secretion rate. EA was calculated based on a 3-day registration of energy intake and expenditure relative to fat-free mass measured in a rested, fasted state using indirect calorimetry (Torstveit et al., 2018 February, International Journal of Sport Nutrition and Exercise Metabolism, 1–28). We used a zero-inflated negative binomial model to investigate the relationship between baseline VO2peak, health-related biomarkers and URI incidence/duration/global URS severity. Fourteen athletes(56%) reported an episode of URI during the four-week monitoring period. Higher sIgA was associated with reduced risk of URI (odds ratio = 0.90, 90% confidence interval (CI): [0.83,0.97]). Lower plasma cortisol (P = 0.02) and higher EA (P = 0.02) were associated with longer URI duration; holding cortisol constant, the incidence risk ratio (IRR) for a one-unit increase in EA was 1.04 (90% CI: [1.01, 1.07]). Participants with higher VO2peak reported higher total symptom scores during the intervention period (P = 0.03, IRR = 1.07, 90% CI: [1.01,1.13]). Several health-related biomarkers and physiological parameters may therefore be associated with risk and severityof URI, including sIgA, cortisol, EA and VO2peak.

Place, publisher, year, edition, pages
Routledge, 2018
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-34995 (URN)10.1080/02640414.2018.1521633 (DOI)
Conference
BASES Conference 2018, 27-28 November 2018, Harrogate, UK
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-12-19Bibliographically approved
Garvican-Lewis, L. A., Vuong, V. L., Govus, A. D., Schumacher, Y. O., Hughes, D., Lovell, G., . . . Gore, C. J. (2018). Influence of combined iron supplementation and simulated hypoxia on the haematological module of the athlete biological passport. Drug Testing and Analysis, 10(4), 731-741
Open this publication in new window or tab >>Influence of combined iron supplementation and simulated hypoxia on the haematological module of the athlete biological passport
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2018 (English)In: Drug Testing and Analysis, ISSN 1942-7603, E-ISSN 1942-7611, Vol. 10, no 4, p. 731-741Article in journal (Refereed) Published
Abstract [en]

The integrity of the athlete biological passport (ABP) is underpinned by understanding normal fluctuations of its biomarkers to environmental or medical conditions, for example, altitude training or iron deficiency. The combined impact of altitude and iron supplementation on the ABP was evaluated in endurance-trained athletes (n = 34) undertaking 3 weeks of simulated live-high: train-low (14 h.d(-1), 3000 m). Athletes received either oral, intravenous (IV) or placebo iron supplementation, commencing 2 weeks prior and continuing throughout hypoxic exposure. Venous blood was sampled twice prior, weekly during, and up to 6 weeks after altitude. Individual ABP thresholds for haemoglobin concentration ([Hb]), reticulocyte percentage (%retic), and OFF score were calculated using the adaptive model and assessed at 99% and 99.9% specificity. Eleven athletes returned values outside of the calculated reference ranges at 99%, with 8 at 99.9%. The percentage of athletes exceeding the thresholds in each group was similar, but IV returned the most individual occurrences. A similar frequency of abnormalities occurred across the 3 biomarkers, with abnormal [Hb] and OFF score values arising mainly during-, and %retic values mainly post-altitude. Removing samples collected during altitude from the model resulted in 10 athletes returning abnormal values at 99% specificity, 2 of whom had not triggered the model previously. In summary, the abnormalities observed in response to iron supplementation and hypoxia were not systematic and mostly in line with expected physiological adaptations. They do not represent a uniform weakness in the ABP. Nevertheless, altitude training and iron supplementation should be carefully considered by experts evaluating abnormal ABP profiles.

Keywords
ferric carboxymaltose, altitude, anti-doping, adaptive model
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33629 (URN)10.1002/dta.2303 (DOI)000430284700013 ()28929623 (PubMedID)2-s2.0-85037634656 (Scopus ID)
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-03-25Bibliographically approved
Hanstock, H., Govus, A., Stenqvist, T. B., Melin, A. K., Sylta, Ö. & Torstveit, M. K. (2018). Influence of interval duration on immunological responses to 4-weeks’ high-intensity interval training. In: Journal of Sports Sciences: BASES Conference 2018 – Programme and Abstracts. Paper presented at BASES Conference 2018, 27-28 November, Harrogate, UK (pp. 1-94). Routledge, 36 (S1)
Open this publication in new window or tab >>Influence of interval duration on immunological responses to 4-weeks’ high-intensity interval training
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2018 (English)In: Journal of Sports Sciences: BASES Conference 2018 – Programme and Abstracts, Routledge, 2018, Vol. 36 (S1), p. 1-94Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

High-intensity interval training (HIT) encompasses a wide range of training prescriptions where up to nine variables can be manipulated (Buchheit and Laursen, 2013, Sports Medicine, 43(5), 313–338). Four weeks of HIT with longer intervals and accumulated work durations (AWD) has been shown to elicit greater improvements in peak oxygen consumption (V O 2peak ) despite more modest physiological, hormonal and perceptual responses (Sylta et al., 2017, Medicine & Science in Sports & Exercise, 49(6), 1137–1146). However, immunological responses to different HIT pre- scriptions have rarely been investigated. The purpose of this study was to compare the cumulative effects of a four-week HIT intervention, performed either as short or long intervals with the same AWD, on V O 2peak , the immunological biomarker salivary secretory IgA (s-IgA) and upper respiratory illness (URI) incidence. In addition, we explored the influence of HIT on serum cortisol, testosterone, 25(OH)D and ferritin as biomarkers related to immune competence. Following local ethics committee approval, twenty-five well-trained male cyclists and triath- letes provided written consent to take part and were randomised to one of three HIT groups (Long Intervals [LI]: 4 × 8min; Short Intervals 1 [SI1]: 4×[12 × 40/20s]; Short Intervals 2 [SI2]: 4×[8 ×40/20s]). Participants per- formed three cycling HIT sessions per week for four weeks at maximal session effort (“isoeffort”) intensity, supplemented with ad libitumlow-intensity training. Participants recorded upper respiratory symptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively. V O 2peak as well as rested saliva and blood biomarkers were analysed before and after the training period. Fourteen of twenty-five participants reported an episode of URI (LI: 4/8, SI1: 4/8, SI2: 6/9) but there were no differences in URI incidence, severity or duration between groups. Following the train- ing intervention, we observed a moderate increase in V O 2peak across the cohort (mean± SD: 4.75 ± 0.42 to 4.86 ± 0.43 L· min−1 ,Cohen’s d= 0.65, 90% confidence intervals: [0.16, 1.13]) but the change in V O 2peak was not different between groups. Serum cortisol displayed a moderate increase (367 ± 98 to 415 ± 108 nmol· L −1 ,d=0.60 [0.12, 1.08]) and 25(OH)D a large decrease (79.2 ± 17.1 to 70.4 ± 17.6 nmol· L −1 ,d= -0.87 [−1.36,−0.37]) from pre- to post-training, but there were no differences in the magnitude of the responses between groups. Four weeks’HIT did not influence s-IgA secretion rate, serum testosterone or ferritin. We conclude that four weeks’ AWD-matched HIT performed as short- or long-intervals at isoeffort intensity does not differentially influence ill- ness incidence, immunological responses to training nor other immune-related biomarkers. This observation can be viewed as a positive finding for training planning, since it could allow coaches some flexibility in constructing AWD-matched isoeffort HIT sessions to achieve performance goals, without concern about detrimental effects on athletes’ immune status.

Place, publisher, year, edition, pages
Routledge, 2018
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-34997 (URN)10.1080/02640414.2018.1521633 (DOI)
Conference
BASES Conference 2018, 27-28 November, Harrogate, UK
Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2019-01-15Bibliographically approved
Garvican-Lewis, L. A., Vuong, V. L., Govus, A. D., Peeling, P., Jung, G., Nemeth, E., . . . Gore, C. J. (2018). Intravenous Iron Does Not Augment the Hemoglobin Mass Response to Simulated Hypoxia. Medicine & Science in Sports & Exercise, 50(8), 1669-1678
Open this publication in new window or tab >>Intravenous Iron Does Not Augment the Hemoglobin Mass Response to Simulated Hypoxia
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2018 (English)In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 50, no 8, p. 1669-1678Article in journal (Refereed) Published
Abstract [en]

Purpose Iron is integral for erythropoietic adaptation to hypoxia, yet the importance of supplementary iron compared with existing stores is poorly understood. The aim of the present study was to compare the magnitude of the hemoglobin mass (Hb(mass)) in response to altitude in athletes with intravenous (IV), oral, or placebo iron supplementation. Methods Thirty-four, nonanemic, endurance-trained athletes completed 3 wk of simulated altitude (3000 m, 14 hd(-1)), receiving two to three bolus iron injections (ferric carboxymaltose), daily oral iron supplementation (ferrous sulfate), or a placebo, commencing 2 wk before and throughout altitude exposure. Hb(mass) and markers of iron regulation were assessed at baseline (day -14), immediately before (day 0), weekly during (days 8 and 15), and immediately, 1, 3, and 6 wk after (days 22, 28, 42, and 63) the completion of altitude exposure. Results Hb(mass) significantly increased after altitude exposure in athletes with IV (mean % [90% confidence interval (CI)], 3.7% [2.8-4.7]) and oral (3.2% [2.2-4.2]) supplementation and remained elevated at 7 d postaltitude in oral (2.9% [1.5-4.3]) and 21 d after in IV (3.0% [1.5-4.6]) supplementation. Hb(mass) was not significantly higher than baseline at any time point in placebo. Conclusions Iron supplementation appears necessary for optimal erythropoietic adaptation to altitude exposure. IV iron supplementation during 3 wk of simulated live high-train low altitude training offered no additional benefit in terms of the magnitude of the erythropoietic response for nonanemic endurance athletes compared with oral supplementation.

Keywords
Ferric Carboxymaltose, Erythroferrone, Hepcidin, Hemoglobin Mass, Altitude Training
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34229 (URN)10.1249/MSS.0000000000001608 (DOI)000438542000016 ()29538179 (PubMedID)2-s2.0-85049833929 (Scopus ID)
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-09-28Bibliographically approved
Govus, A. D., Coutts, A., Duffield, R., Murray, A. & Fullagar, H. (2018). Relationship between pretraining subjective wellness measures, player load, and rating-of-perceived-exertion training load in American college football. International Journal of Sports Physiology and Performance, 13(1), 95-101
Open this publication in new window or tab >>Relationship between pretraining subjective wellness measures, player load, and rating-of-perceived-exertion training load in American college football
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2018 (English)In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 13, no 1, p. 95-101Article in journal (Refereed) Published
Abstract [en]

Context: The relationship between pretraining subjective wellness and external and internal training load in American college football is unclear. Purpose: To examine the relationship of pretraining subjective wellness (sleep quality, muscle soreness, energy, wellness Z score) with player load and session rating of perceived exertion (s-RPE-TL) in American college football players. Methods: Subjective wellness (measured using 5-point, Likert-scale questionnaires), external load (derived from GPS and accelerometry), and s-RPE-TL were collected during 3 typical training sessions per week for the second half of an American college football season (8 wk). The relationship of pretraining subjective wellness with player load and s-RPE training load was analyzed using linear mixed models with a random intercept for athlete and a random slope for training session. Standardized mean differences (SMDs) denote the effect magnitude. Results: A 1-unit increase in wellness Z score and energy was associated with trivial 2.3% (90% confidence interval [CI] 0.5, 4.2; SMD 0.12) and 2.6% (90% CI 0.1, 5.2; SMD 0.13) increases in player load, respectively. A 1-unit increase in muscle soreness (players felt less sore) corresponded to a trivial 4.4% (90% CI ?8.4, ?0.3; SMD ?0.05) decrease in s-RPE training load. Conclusion: Measuring pretraining subjective wellness may provide information about players’ capacity to perform in a training session and could be a key determinant of their response to the imposed training demands American college football. Hence, monitoring subjective wellness may aid in the individualization of training prescription in American college football players.

National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-33084 (URN)10.1123/ijspp.2016-0714 (DOI)000429366800017 ()28488913 (PubMedID)2-s2.0-85041805349 (Scopus ID)
Available from: 2018-02-26 Created: 2018-02-26 Last updated: 2018-05-08Bibliographically approved
Andersson, E. P., Govus, A., Shannon, O. M. & McGawley, K. (2018). Sex differences in performance and pacing strategies during a sprint time-trial in cross-country skiing. In: : . Paper presented at Paper presented at the 23d annual Congress of the European College of Sport Science ECSS, Dublin, 4-7th July, 2018.
Open this publication in new window or tab >>Sex differences in performance and pacing strategies during a sprint time-trial in cross-country skiing
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

INTRODUCTION: The aim of this study was to compare the pacing strategies, choice of sub-technique (i.e., gear) and overall performance between elite male and female cross-country (XC) skiers during a ski-skating sprint time-trial (TT) on snow.

METHODS: Thirty-four elite XC skiers (20 males and 14 females: age, 23 ± 4 and 21 ± 3 yr; body mass, 76 ± 8 and 64 ± 5 kg; height, 183 ± 7 and 171 ± 5 cm; sprint FIS points, 86 ± 42 and 90 ± 54) performed a 1.6 km TT, which was 56% flat (or undulating), 21% uphill and 22% downhill. The sprint course was measured with a differential global navigation satellite system and divided into four flat, three uphill and two downhill sections. Race time was measured with the EMIT timing system (Emit AS, Oslo, Norway) and one 25-m uphill (4°) section was filmed continuously with a fixed camcorder (50 Hz). All skiers used a similar stone-grind and all skis were glide-waxed similarly. The air temperature was +1°C (fresh snow at ±0°C), relative humidity was 90% and the friction coefficient between ski and snow was estimated to 0.045 (i.e., very slow).

RESULTS: Average speed during the TT was 25 ± 1 and 22 ± 1 km/h (TT time: 227 ± 11 and 254 ± 10 s) for males and females, respectively (P < 0.001, Cohen’s d effect size [ES] = 2.6). Average relative power output (PO) was estimated to 3.9 ± 0.3 and 3.3 ± 0.2 W/kg for males and females, respectively (P < 0.001, ES = 2.5). Average heart rate was 95 ± 2% and 96 ± 1% of maximum for males and females (P = 0.51), with a 2-min post-race blood lactate concentration of 10 ± 2 mmol/L for both sexes (P = 0.64). Within-athlete coefficient of variation in speed between sections was 20 ± 2% for males and 24 ± 1% for females (P < 0.001, ES = 2.6). Speeds on the flat, uphill and downhill sections were 26 ± 1, 19 ± 1 and 32 ± 1 km/h for males and 23 ± 1, 16 ± 1 and 30 ± 1 km/h for females (main effects for terrain, sex and interaction, all P < 0.01) corresponding to 9%, 16% and 8% slower speeds on flat, uphill and downhill terrain for females. Speeds relative to the average TT speed were 103 ± 1%, 77 ± 2% and 129 ± 4% for males and 105 ± 1%, 72 ± 2% and 133 ± 2% for females (main effects for terrain, sex and interaction, all P < 0.001). Relative PO on the flat, uphill and downhill sections were estimated to 4.0 ± 0.3, 4.9 ± 0.4 and 1.9 ± 0.2 W/kg for males and 3.5 ± 0.2, 4.0 ± 0.3 and 1.5 ± 0.2 W/kg for females (main effects for terrain, sex and interaction, all P < 0.001). The males were 20% faster than the females on the uphill video section (16 ± 1 versus 13 ± 1 km/h, P < 0.001, ES = 2.6), with 95% of the male skiers and 21% of the female skiers using gear 3 exclusively, and the remaining skiers using gear 2 exclusively or a combination of gears 2 and 3.

CONCLUSION: The present results indicate an overall sex difference in sprint skiing performance of ~12% and reveal differences in terrain-specific pacing as well as gear choice between sexes with females showing a higher overall variation in speed and considerably slower uphill skiing.

National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-34772 (URN)
Conference
Paper presented at the 23d annual Congress of the European College of Sport Science ECSS, Dublin, 4-7th July, 2018
Available from: 2018-10-23 Created: 2018-10-23 Last updated: 2018-10-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6224-0454

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