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  • 1.
    Andersson, Erik
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. La Trobe University, Melbourne, VIC, Australia.
    Shannon, Oliver Michael
    Newcastle University, Newcastle upon Tyne, United Kingdom.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Sex differences in performance and pacing strategies during sprint skiing2019In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 295Article in journal (Refereed)
    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.

  • 2.
    Andersson, Erik P.
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    Department of Rehabilitation, Nutrition and Sport, La Trobe University, Australia.
    Shannon, Oliver M.
    Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, United Kingdom.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Sex differences in performance and pacing strategies during a sprint time-trial in cross-country skiing2018Conference paper (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.

  • 3.
    Carr, Amelia
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Deakin University, Burwood, Victoria, Australia.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Shannon, Oliver M.
    Newcastle University, Newcastle upon Tyne, United Kingdom.
    Mattsson, Stig
    Örebro University, Örebro, Sweden.
    Melin, Anna K.
    University of Copenhagen, Copenhagen, Denmark.
    Nutritional Intake in Elite Cross-Country Skiers During Two Days of Training and Competition2019In: International Journal of Sport Nutrition & Exercise Metabolism, ISSN 1526-484X, E-ISSN 1543-2742, Vol. 29, no 3, p. 273-281Article in journal (Refereed)
    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.

  • 4.
    Carr, Amelia
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Deakin University, Australia.
    Melin, Anna
    University of Copenhagen.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Shannon, Oliver
    Leeds Beckett University, UK.
    Provis, Holly
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsson, Mathilda
    Mattson, Stig
    Swedish Olympic Committee.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Nutritional intake in elite cross-country skiers during a simulated sprint race2017Conference paper (Refereed)
    Abstract [en]

    Introduction: Habitual nutritional intakes in cross-country skiers have previously been reported (Fogelholm et al., 1992), however in elite cross-country skiers there is limited knowledge about race-specific nutritional practices, or the prevalence of dehydration and persistent low energy availability (EA). This study aimed to investigate, in the context of a simulated sprint race, energy intake, macronutrient intake, hydration status and the risk of persistent low EA in elite cross-country skiers. Methods: Thirty-two male (n = 18) and female (n = 14) elite Swedish cross-country skiers completed weighed food records the day prior to (day 1) and the day of a simulated sprint race (day 2); the food records were analysed for energy (kcal/kg), macronutrient (g/kg) and fluid intake (L). Urine specific gravity (USG) was also measured on day 1 and day 2. The risk for persistent low EA was assessed in the female skiers using the Low Energy Availability in Females Questionnaire (LEAF-Q; Melin et al., 2014). Results were analysed using a three-way mixed ANOVA. Statistical significance was set to a level of p ≤ 0.05. Results: Males had a higher energy intake (65±9 kcal/kg) on day 1, (pre-race) compared with day 2 (simulated sprint race; 58±9kcal/kg; p = 0.002). Females consumed 57±10 kcal/kg on day 1, which was similar to their day 2 energy intake (54±6 kcal on day 2; p > 0.05). Males consumed less carbohydrate (8.2±2.3g/kg) on day 1 compared with day 2 (8.9±2.3g/kg) (p = 0.026), as did females, consuming 7.0±1.5g/kg on day 1, and 8.4±1.7g/kg on day 2 (p = 0.003). There were similar fluid intakes across the two days for males (p > 0.05) and females (p > 0.05). Nine of the 18 males and 6 of the 14 females were dehydrated (USG > 1.020) on day 1, and 9 males and 5 females were dehydrated on day 2. Five of the 14 females were classified as being at risk of persistent low EA. Discussion: This study provides an initial insight into nutritional competition habits in elite cross-country skiers. The findings indicate that elite skiers’ nutritional intakes are consistent with guidelines, particularly those for endurance athletes’ carbohydrate intake for competitive events (Burke et al., 2001). There was however some evidence of persistent low EA and dehydration, suggesting additional considerations that may be relevant to cross-country skiers’ nutritional intakes for sprint races.

  • 5.
    Foster, Josh
    et al.
    Institute for Sport and Physical Activity Research University of Bedfordshire, Bedford, UK.
    Mauger, Alexis R.
    Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, United Kingdom.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hewson, David
    Institute for Health Research, University of Bedfordshire, Luton, United Kingdom.
    Taylor, Lee
    ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Aspire Zone, Doha, Qatar.
    Acetaminophen (Paracetamol) Induces Hypothermia During Acute Cold Stress2017In: Clinical drug investigation, ISSN 1173-2563, E-ISSN 1179-1918, Vol. 37, no 11, p. 1055-1065Article in journal (Refereed)
    Abstract [en]

    Background: Acetaminophen is an over-the-counter drug used to treat pain and fever, but it has also been shown to reduce core temperature (Tc) in the absence of fever. However, this side effect is not well examined in humans, and it is unknown if the hypothermic response to acetaminophen is exacerbated with cold exposure. Objective: To address this question, we mapped the thermoregulatory responses to acetaminophen and placebo administration during exposure to acute cold (10 °C) and thermal neutrality (25 °C). Methods: Nine healthy Caucasian males (aged 20–24 years) participated in the experiment. In a double-blind, randomised, repeated measures design, participants were passively exposed to a thermo-neutral or cold environment for 120 min, with administration of 20 mg/kg lean body mass acetaminophen or a placebo 5 min prior to exposure. Tc, skin temperature (Tsk), heart rate, and thermal sensation were measured every 10 min, and mean arterial pressure was recorded every 30 min. Data were analysed using linear mixed effects models. Differences in thermal sensation were analysed using a cumulative link mixed model. Results: Acetaminophen had no effect on Tc in a thermo-neutral environment, but significantly reduced Tc during cold exposure, compared with a placebo. Tc was lower in the acetaminophen compared with the placebo condition at each 10-min interval from 80 to 120 min into the trial (all p &lt; 0.05). On average, Tc decreased by 0.42 ± 0.13 °C from baseline after 120 min of cold exposure (range 0.16–0.57 °C), whereas there was no change in the placebo group (0.01 ± 0.1 °C). Tsk, heart rate, thermal sensation, and mean arterial pressure were not different between conditions (p &gt; 0.05). Conclusion: This preliminary trial suggests that acetaminophen-induced hypothermia is exacerbated during cold stress. Larger scale trials seem warranted to determine if acetaminophen administration is associated with an increased risk of accidental hypothermia, particularly in vulnerable populations such as frail elderly individuals. 

  • 6.
    Fullagar, Hugh H. K.
    et al.
    Univ Oregon, Dept Athlet Football, Eugene, OR, USA.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hanisch, James
    Philadelphia Eagles, Philadelphia, PA USA.
    Murray, Andrew
    Univ Oregon, Dept Athlet Football, Eugene, OR, USA.
    The Time Course of Perceptual Recovery Markers After Match Play in Division I-A College American Football2017In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 12, no 9, p. 1264-1266Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the recovery time course of customized wellness markers (sleep, soreness, energy, and overall wellness) in response to match play in American Division I-A college football players. Methods: A retrospective research design was used. Wellness data were collected and analyzed for 2 American college football seasons. Perceptions of soreness, sleep, energy, and overall wellness were obtained for the day before each game (GD-1) and the days after each game (GD+2, GD+3, and GD+4). Standardized effect-size (ES) analyses +/- 90% confidence intervals were used to interpret the magnitude of the mean differences between all time points for the start, middle, and finish of the season, using the following qualitative descriptors: 0-0.19 trivial, 0.2-0.59 small, 0.6-1.19 moderate, 1.2-1.99 large, <2.0 very large. Results: Overall wellness showed small ES reductions on GD+2 (d = 0.22 +/- 0.09, likely [94.8%]), GD+3 (d = 0.37 +/- 0.15, very likely), and GD+4 (d = 0.29 +/- 0.12, very likely) compared with GD-1. There were small ES reductions for soreness between GD-1 and GD+2, GD+3, and GD+4 (d = 0.21 +/- 0.09, likely, d = 0.29 +/- 0.12, very likely, and 0.30 +/- 0.12, very likely, respectively). Small ES reductions were also evident between GD-1 and GD+3 (d = 0.21 +/- 0.09, likely) for sleep. Feelings of energy showed small ESs on GD+3 (d = 0.27 +/- 0.11, very likely) and GD+4 (d = 0.22 +/- 0.09, likely) compared with GD-1. Conclusion: All wellness markers were likely to very likely worse on GD+3 and GD+4 than on GD-1. These findings show that perceptual wellness takes longer than 4 d to return to pregame levels and thus should be considered when prescribing training and/or recovery.

  • 7.
    Garvican-Lewis, Laura A.
    et al.
    Australian Catholic Univ, Mary Mackillop Inst Hlth Res, Melbourne, Vic, Australia; Australian Inst Sport, Canberra, ACT, Australia.
    Vuong, Victor L.
    Australian Inst Sport, Canberra, ACT, Australia.
    Govus, Andrew D.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Peeling, Peter
    Western Australian Inst Sport, Perth, WA, Australia; Univ Western Australia, Sch Human Sci Exercise & Sports Sci, Perth, WA, Australia.
    Jung, Grace
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Los Angeles, CA, USA.
    Nemeth, Elizabeta
    Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Los Angeles, CA, USA.
    Hughes, David
    Australian Inst Sport, Canberra, ACT, Australia.
    Lovell, Greg
    Australian Inst Sport, Canberra, ACT, Australia.
    Eichner, Daniel
    Sports Med Res & Testing Lab, Salt Lake City, UT USA.
    Gore, Christopher J.
    Australian Inst Sport, Canberra, ACT, Australia.
    Intravenous Iron Does Not Augment the Hemoglobin Mass Response to Simulated Hypoxia2018In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 50, no 8, p. 1669-1678Article in journal (Refereed)
    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.

  • 8.
    Garvican-Lewis, Laura A.
    et al.
    Australian Catholic Univ, Melbourne, Australia; Australian Inst Sport, Canberra, Australia.
    Vuong, Victor L.
    Australian Inst Sport, Canberra, Australia.
    Govus, Andrew D.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schumacher, Yorck Olaf
    Aspetar Orthopaed & Sports Med Hosp, Doha, Qatar.
    Hughes, David
    Australian Inst Sport, Canberra, Australia.
    Lovell, Greg
    Australian Inst Sport, Canberra, Australia.
    Eichner, Daniel
    Sports Med Res & Testing Lab, Salt Lake City, UT, USA.
    Gore, Christopher J.
    Australian Inst Sport, Canberra, Australia.
    Influence of combined iron supplementation and simulated hypoxia on the haematological module of the athlete biological passport2018In: Drug Testing and Analysis, ISSN 1942-7603, E-ISSN 1942-7611, Vol. 10, no 4, p. 731-741Article in journal (Refereed)
    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.

  • 9.
    Govus, Andrew
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik P.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Shannon, Oliver M.
    Newcastle University, UK.
    Provis, Holly
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsson, Mathilda
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Commercially available compression garments or electrical stimulation do not enhance recovery following a sprint competition in elite cross-country skiers2018In: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 18, no 10, p. 1299-1308Article in journal (Refereed)
    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.

  • 10.
    Govus, Andrew
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Shannon, Oliver
    Provis, Holly
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Karlsson, Mathilda
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Compression garments and electrical stimulation do not enhance recovery from a cross-country sprint skiing competition2017Conference paper (Refereed)
    Abstract [en]

    Purpose: To investigate whether compression garments (CG) and neuromuscular electrical stimulation (NMES) augment post-race recovery compared with a passive control group (CON) following a cross-country sprint skiing competition. Methods: Twenty-one senior (12 males, 9 females) and 11 junior (6 males, 5 females) Swedish national team skiers performed a sprint skiing competition involving four, ~3-4 min sprints. After the race, skiers were matched by sex and skiing level (senior versus junior) and randomly assigned to a CON (n = 10), CG (n = 11) or NMES group (n = 11). Creatine kinase (CK) and urea, countermovement jump height (CMJ) and perceived sleep duration, sleep quality and muscle pain were measured before and 8, 20, 44 and 68 h after the race to assess the efficacy of each recovery intervention. Results: Neither CG nor NMES promoted the recovery of blood biomarkers, perceived wellness nor CMJ post-race compared with the passive control group (all P < 0.05). When grouping all 32 participants, CK, urea and muscle pain increased from pre-race values, peaking 20-44 h post-race (P < 0.05). CMJ was lower than pre-race values 44 and 60 h post-race in males and females (both P < 0.05). Sleep duration increased from pre-race to post-race (P < 0.05), whereas sleep quality was unchanged (P > 0.05). Conclusion: A cross-country sprint skiing competition induced symptoms of exercise-induced muscle damage peaking 20-44 h post-race. However, CG and NMES did not augment the recovery of physiological, perceptual or performance parameters compared with a passive control group after the sprint skiing competition.

  • 11.
    Govus, Andrew D.
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Coutts, Aaron
    University of Technology (UTS), Sydney, Australia.
    Duffield, Rob
    University of Technology (UTS), Sydney, Australia.
    Murray, Andrew
    University of Oregon, Eugene, OR, United States.
    Fullagar, Hugh
    University of Oregon, Eugene, OR, United States.
    Relationship between pretraining subjective wellness measures, player load, and rating-of-perceived-exertion training load in American college football2018In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 13, no 1, p. 95-101Article in journal (Refereed)
    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.

  • 12.
    Hanstock, Helen
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    University of Agder, Norway.
    Stenqvist, Thomas B
    University of Copenhagen, Denmark.
    Melin, Anna K
    University of Copenhagen, Denmark.
    Sylta, Öystein
    Agder University, Norway.
    Torstveit, Monica K
    Agder University, Norway.
    Influence of interval duration on immunological responses to 4-weeks’ high-intensity interval training2018In: Journal of Sports Sciences: BASES Conference 2018 – Programme and Abstracts, Routledge, 2018, Vol. 36 (S1), p. 1-94Conference paper (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.

  • 13.
    Hanstock, Helen
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Stenqvist, Thomas B.
    University of Agder, Norway.
    Melin, Anna K.
    University of Copenhagen, Denmark.
    Sylta, Øystein
    University of Agder, Norway.
    Torstveit, Monica K.
    University of Agder, Norway.
    Influence of Immune and Nutritional Biomarkers on Illness Risk During Interval Training2020In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 15, no 1, p. 60-67Article in journal (Refereed)
    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.

  • 14.
    Hanstock, Helen
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Govus, Andrew
    University of Agder, Norway.
    Stenqvist, Thomas B
    University of Copenhagen, Denmark.
    Melin, Anna
    University of Copenhagen, Denmark.
    Sylta, Öystein
    University of Agder, Norway.
    Torstveit, Monica K
    University of Agder, Norway.
    Evaluation of physiological and nutritional risk factors for upper respiratory illness using a zero-inflated negative binomial model2018In: Journal of Sports Sciences: Volume 36, 2018 - Issue sup1: BASES Conference 2018 – Programme and Abstracts, Routledge, 2018, Vol. 36 (S1), p. 44-45Conference paper (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.

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