| 1. |
- Fullagar, Hugh H. K., et al.
(författare)
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The Time Course of Perceptual Recovery Markers After Match Play in Division I-A College American Football
- 2017
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Ingår i: International Journal of Sports Physiology and Performance. - : Human Kinetics. - 1555-0265 .- 1555-0273. ; 12:9, s. 1264-1266
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Govus, Andrew D., et al.
(författare)
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Relationship between pretraining subjective wellness measures, player load, and rating-of-perceived-exertion training load in American college football
- 2018
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Ingår i: International Journal of Sports Physiology and Performance. - : Human Kinetics. - 1555-0265 .- 1555-0273. ; 13:1, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Andersson, Erik P., 1984-, et al.
(författare)
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Sex differences in performance and pacing strategies during a sprint time-trial in cross-country skiing
- 2018
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 4. |
- Andersson, Erik, 1984-, et al.
(författare)
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Sex differences in performance and pacing strategies during sprint skiing
- 2019
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- 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˙" 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˙" 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˙" 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.
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| 5. |
- Carr, Amelia, et al.
(författare)
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Nutritional intake in elite cross-country skiers during a simulated sprint race
- 2017
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 6. |
- Carr, Amelia, et al.
(författare)
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Nutritional Intake in Elite Cross-Country Skiers During Two Days of Training and Competition
- 2019
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Ingår i: International Journal of Sport Nutrition & Exercise Metabolism. - Birmingham : Human Kinetics. - 1526-484X .- 1543-2742. ; 29:3, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the energy, macronutrient, and fluid intakes, as well as hydration status (urine specific gravity), in elite cross-country skiers during a typical day of training (Day 1) and a sprint skiing competition the following day (Day 2). A total of 31 (18 males and 13 females) national team skiers recorded their food and fluid intakes and urine specific gravity was measured on Days 1 and 2. In addition, the females completed the Low Energy Availability in Females Questionnaire to assess their risk of long-term energy deficiency. Energy intake for males was 65 ± 9 kcal/kg on Day 1 versus 58 ± 9 kcal/kg on Day 2 (p = .002) and for females was 57 ± 10 on Day 1 versus 55 ± 5 kcal/kg on Day 2 (p = .445). Carbohydrate intake recommendations of 10-12 g·kg-1·day-1 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 postexercise 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 1, 50% of males and 46% of females were dehydrated; on Day 2, 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 of long-term energy deficiency. Furthermore, many of the athletes were dehydrated prior to training and competition.
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| 7. |
- Foster, Josh, et al.
(författare)
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Acetaminophen (Paracetamol) Induces Hypothermia During Acute Cold Stress
- 2017
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Ingår i: Clinical drug investigation. - : Springer Science and Business Media LLC. - 1173-2563 .- 1179-1918. ; 37:11, s. 1055-1065
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Tidskriftsartikel (refereegranskat)abstract
- 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 < 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 > 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.
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| 8. |
- Garvican-Lewis, Laura A., et al.
(författare)
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Influence of combined iron supplementation and simulated hypoxia on the haematological module of the athlete biological passport
- 2018
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Ingår i: Drug Testing and Analysis. - : Wiley. - 1942-7603 .- 1942-7611. ; 10:4, s. 731-741
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Garvican-Lewis, Laura A., et al.
(författare)
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Intravenous Iron Does Not Augment the Hemoglobin Mass Response to Simulated Hypoxia
- 2018
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Ingår i: Medicine & Science in Sports & Exercise. - 0195-9131 .- 1530-0315. ; 50:8, s. 1669-1678
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Govus, Andrew, et al.
(författare)
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Commercially available compression garments or electrical stimulation do not enhance recovery following a sprint competition in elite cross-country skiers
- 2018
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Ingår i: European Journal of Sport Science. - : Informa UK Limited. - 1746-1391 .- 1536-7290. ; 18:10, s. 1299-1308
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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