miun.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 55) Show all publications
Pettersson, S., Edin, F., Bakkman, L. & McGawley, K. (2019). Effects of supplementing with an 18% carbohydrate-hydrogel drink versus a placebo during whole-body exercise in -5 °C with elite cross-country ski athletes: a crossover study. Journal of the International Society of Sports Nutrition, 16(1), Article ID 46.
Open this publication in new window or tab >>Effects of supplementing with an 18% carbohydrate-hydrogel drink versus a placebo during whole-body exercise in -5 °C with elite cross-country ski athletes: a crossover study
2019 (English)In: Journal of the International Society of Sports Nutrition, ISSN 1550-2783, E-ISSN 1550-2783, Vol. 16, no 1, article id 46Article in journal (Refereed) Published
Abstract [en]

BACKGROUND:

Whilst the ergogenic effects of carbohydrate intake during prolonged exercise are well-documented, few investigations have studied the effects of carbohydrate ingestion during cross-country skiing, a mode of exercise that presents unique metabolic demands on athletes due to the combined use of large upper- and lower-body muscle masses. Moreover, no previous studies have investigated exogenous carbohydrate oxidation rates during cross-country skiing. The current study investigated the effects of a 13C-enriched 18% multiple-transportable carbohydrate solution (1:0.8 maltodextrin:fructose) with additional gelling polysaccharides (CHO-HG) on substrate utilization and gastrointestinal symptoms during prolonged cross-country skiing exercise in the cold, and subsequent double-poling time-trial performance in ~ 20 °C.

METHODS:

Twelve elite cross-country ski athletes (6 females, 6 males) performed 120-min of submaximal roller-skiing (69.3 ± 2.9% of [Formula: see text]O2peak) in -5 °C while receiving either 2.2 g CHO-HG·min- 1 or a non-caloric placebo administered in a double-blind, randomized manner. Whole-body substrate utilization and exogenous carbohydrate oxidation was calculated for the last 60 min of the submaximal exercise. The maximal time-trial (2000 m for females, 2400 m for males) immediately followed the 120-min submaximal bout. Repeated-measures ANOVAs with univariate follow-ups were conducted, as well as independent and paired t-tests, and significance was set at P < 0.05. Data are presented as mean ± SD.

RESULTS:

Exogenous carbohydrate oxidation contributed 27.6 ± 6.6% to the total energy yield with CHO-HG and the peak exogenous carbohydrate oxidation rate reached 1.33 ± 0.27 g·min- 1. Compared to placebo, fat oxidation decreased by 9.5 ± 4.8% with CHO-HG, total carbohydrate oxidation increased by 9.5 ± 4.8% and endogenous carbohydrate utilization decreased by 18.1 ± 6.4% (all P < 0.05). No severe gastrointestinal symptoms were reported in either trial and euhydration was maintained in both trials. Time-trial performance (8.4 ± 0.4 min) was not improved following CHO-HG compared to placebo (- 0.8 ± 3.5 s; 95% confidence interval - 3.0 to 1.5 s; P = 0.46). No sex differences were identified in substrate utilization or relative performance.

CONCLUSIONS:

Ingestion of an 18% multiple-transportable carbohydrate solution with gelling polysaccharides was found to be well-tolerated during 120 min of submaximal whole-body exercise, but did not improve subsequent maximal double-poling performance.

Keywords
Biathlete, Cold, Double-poling, Endurance, Roller-skiing, Sex differences, Stabile isotopes, Substrate utilization, World-class
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-37600 (URN)10.1186/s12970-019-0317-4 (DOI)000493122300001 ()31655603 (PubMedID)2-s2.0-85074136199 (Scopus ID)
Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2019-11-15Bibliographically approved
McGawley, K. (2019). Field-based analyses in cross-country skiing and biathlon. In: : . Paper presented at Nordic Winter Sports Conference, Meråker, Norway, May 9-10, 2019. Meråker
Open this publication in new window or tab >>Field-based analyses in cross-country skiing and biathlon
2019 (English)Conference paper, Oral presentation only (Other academic)
Place, publisher, year, edition, pages
Meråker: , 2019
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-37191 (URN)
Conference
Nordic Winter Sports Conference, Meråker, Norway, May 9-10, 2019
Available from: 2019-09-11 Created: 2019-09-11 Last updated: 2019-10-30Bibliographically 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
Show others...
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
Jonsson, M., McGawley, K. & Laaksonen, M. (2019). Rifle carriage decreases speed at lactate threshold, anaerobic energy contribution and performance in biathlon skiing.. In: : . Paper presented at European College of Sport Science (ECSS) in Prague, 3-6 July, 2019.
Open this publication in new window or tab >>Rifle carriage decreases speed at lactate threshold, anaerobic energy contribution and performance in biathlon skiing.
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Biathlon is an endurance sport combining rifle shooting and intermittent cross-country skiing while carrying a rifle (minimum weight 3.5 kg). Previous studies have shown that the skiing component explains 60% of overall biathlon performance (1) and that rifle carriage affects different physiological responses such as blood lactate, oxygen uptake (VO2) and heart rate during skiing (2, 3). However, the effects of rifle carriage on skiing performance and variables such as maximal VO2 (VO2max), lactate threshold, efficiency of movement and anaerobic energy contribution have not yet been investigated.METHODS:Seventeen biathletes (9 females, 8 males; age 23.0 (3.3) years, VO2max 59.8 (7.3) mL/kg/min), competing at a national and/or international level, and completing approximately three biathlon training sessions/week with the rifle on the back, performed a submaximal incremental test and a 900–1000-m maximal time-trial (TT) using treadmill roller-skiing (gear 3 skating technique) on two occasions separated by at least 48 hours. One condition involved carrying the rifle on the back (WR) and the other no rifle (NR), with the order randomized. The VO2 and skiing speed at 4 mmol/L of blood lactate (VO2@4mmol and speed@4mmol, respectively), gross efficiency (GE), metabolic aerobic (MRae) and anaerobic (MRan) rates, and VO2max were determined. RESULTS:Submaximal VO2 at all levels and GE (16.7 (0.9) vs 16.5 (1.1) %, p<0.05) were higher for WR compared to NR, while speed@4mmol (11.3 (1.5) vs 11.7 (1.5) km/h, p<0.05) and MRan (27.3 (6.7) vs 30.5 (7.6) kJ/min, p<0.01) was lower. There were no differences in VO2@4mmol or MRae between the two conditions. The mean speed during the TT was higher for NR compared to WR (16.5 (1.5) vs 15.5 (1.4) km/h, p<0.001), but there was no difference in VO2max. Mean speed during the TT was correlated to speed@4mmol (WR: r=0.810, p<0.001; NR: r=0.659, p<0.01), GE (WR: r=0.691; NR r=0.529, both p<0.05) and VO2max (WR: r=0.514; NR: r=0.526, both p<0.05). Speed@4mmol together with MRan explained more than 80% of performance in the TT (WR 83.7%, NR 81.5%). There was no difference between male and female biathletes in response to rifle carriage, although the relative mass of the rifle was higher for the females (5.6 (0.4) vs 5.0 (0.4) % of body mass, p<0.01).CONCLUSION:According to this study, the most important variables for skiing speed in biathlon seem to be the speed at lactate threshold combined with the metabolic anaerobic rate, both of which were lower for skiing with the rifle compared to without. In addition, GE was related to biathlon performance and was also affected by rifle carriage. Thus, to improve skiing performance in biathlon, improving speed at the lactate threshold, anaerobic energy delivery and GE while carrying the rifle are recommended.

National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-36825 (URN)
Conference
European College of Sport Science (ECSS) in Prague, 3-6 July, 2019
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-13Bibliographically 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
Karlsson, Ø., Laaksonen, M. & McGawley, K. (2019). Training characteristics of highly-trained cross-country skiers throughout the transition from junior to senior level. In: : . Paper presented at European College of Sport Science (ECSS) in Prague, 3-6 July, 2019.
Open this publication in new window or tab >>Training characteristics of highly-trained cross-country skiers throughout the transition from junior to senior level
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

INTRODUCTION: Reaching an international level in any endurance sport requires a large volume of systematic training performed over time. While the annual training characteristics of senior, elite-level cross-country (XC) skiers are well documented (1), limited data exist regarding the long-term training of developing XC skiers. The current study aimed to describe the training undertaken by a group of highly-trained XC skiers throughout their transition from junior- to senior-level athletes. METHODS: In this retrospective cohort study, self-reported training data were obtained from 32 highly-trained female (n = 13) and male (n = 19) XC skiers for the season they turned 16 years old (y) until the season they turned 23 y. At the time of inclusion, 26 skiers (11 females and 15 males) had represented at least one of the Swedish national teams (senior, development or junior), and eight of these skiers (6 females and 2 males) had won at least one individual U23 or Junior World Championship medal. The remaining six skiers were part of a specialist ski university in Sweden, where selection is based on the potential to perform at a world-class level. Training data were organized by training form (endurance, strength, and speed), mode (e.g. on-snow skiing, roller skiing, running, and cycling), and intensity (using a 4-zone model), which were then divided into five annual training phases (transition, general preparation [GP], specific preparation [SP], competition [CP], regeneration). RESULTS: Data from 155 seasons, including 59 026 individual training sessions and 94 964 h of training, were analysed. From age 16 to 22 y the total volume of endurance training increased from 472 ± 70 to 721 ± 86 h/yr (p < 0.001). Low-intensity training (LIT, below the first lactate threshold, <85% HRmax) and high-intensity training (HIT, above the first lactate threshold, >85% HRmax) increased from 414 ± 61 to 656 ± 72 h/yr (p < 0.001) and 58 ± 33 to 65 ± 16 h/yr (p = 0.018), respectively. The training-volume distribution developed progressively from a more even distribution across training phases at age 16 y (GP: 10.6 ± 1.8 h/wk; SP: 10.4 ± 1.5 h/wk; CP: 8.6 ± 1.5 h/wk) to a more traditional periodised model at age 22 y (GP: 17.5 ± 1.7 h/wk; SP: 12.7 ± 1.9 h/wk; CP: 11.1 ± 2.1 h/wk), whereby a higher proportion of the total training volume was performed in GP, and a lower proportion in SP and CP, as athletes developed. CONCLUSION: In conclusion, this group of highly-trained XC skiers progressively increased their endurance training volume from age 16 to 22 y, to a level that is required of elite XC skiers. This increase in training volume was primarily due to an increase in LIT in the general preparation phase. In addition, training-volume distribution became more periodised as athletes developed from junior to senior level. REFERENCES 1. Ø. Sandbakk & HC. Holmberg, International Journal of Sports Physiology and Performance 9, 117-121 (2014).

National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-37190 (URN)978-3-9818414-2-8 (ISBN)
Conference
European College of Sport Science (ECSS) in Prague, 3-6 July, 2019
Available from: 2019-09-11 Created: 2019-09-11 Last updated: 2019-10-01Bibliographically approved
Andersson, E. & McGawley, K. (2018). A Comparison between Different Methods of Estimating Anaerobic Energy Production. Frontiers in Physiology, 9(FEB), Article ID 82.
Open this publication in new window or tab >>A Comparison between Different Methods of Estimating Anaerobic Energy Production
2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no FEB, article id 82Article in journal (Refereed) Published
Abstract [en]

Purpose: The present study aimed to compare four methods of estimating anaerobic energy production during supramaximal exercise.

Methods: Twenty-one junior cross-country skiers competing at a national and/or international level were tested on a treadmill during uphill (7°) diagonal-stride (DS) roller-skiing. After a 4-minute warm-up, a 4 × 4-min continuous submaximal protocol was performed followed by a 600-m time trial (TT). For the maximal accumulated O2 deficit (MAOD) method the V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2-speed regression relationship was used to estimate the V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2 demand during the TT, either including (4+Y, method 1) or excluding (4-Y, method 2) a fixed Y-intercept for baseline V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2. The gross efficiency (GE) method (method 3) involved calculating metabolic rate during the TT by dividing power output by submaximal GE, which was then converted to a V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2 demand. An alternative method based on submaximal energy cost (EC, method 4) was also used to estimate V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2 demand during the TT.

Results: The GE/EC remained constant across the submaximal stages and the supramaximal TT was performed in 185 ± 24 s. The GE and EC methods produced identical V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2 demands and O2 deficits. The V." role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-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.O2 demand was ~3% lower for the 4+Y method compared with the 4-Y and GE/EC methods, with corresponding O2 deficits of 56 ± 10, 62 ± 10, and 63 ± 10 mL·kg−1, respectively (P < 0.05 for 4+Y vs. 4-Y and GE/EC). The mean differences between the estimated O2 deficits were −6 ± 5 mL·kg−1 (4+Y vs. 4-Y, P < 0.05), −7 ± 1 mL·kg−1 (4+Y vs. GE/EC, P < 0.05) and −1 ± 5 mL·kg−1 (4-Y vs. GE/EC), with respective typical errors of 5.3, 1.9, and 6.0%. The mean difference between the O2 deficit estimated with GE/EC based on the average of four submaximal stages compared with the last stage was 1 ± 2 mL·kg−1, with a typical error of 3.2%.

Conclusions: These findings demonstrate a disagreement in the O2 deficits estimated using current methods. In addition, the findings suggest that a valid estimate of the O2 deficit may be possible using data from only one submaximal stage in combination with the GE/EC method.

Keywords
Anaerobic capacity, Cross-country skiing, Endurance exercise, Energetics, Oxygen deficit, Oxygen demand, Oxygen uptake
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-32837 (URN)10.3389/fphys.2018.00082 (DOI)000424478800001 ()29472871 (PubMedID)2-s2.0-85041823353 (Scopus ID)
Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-03-19Bibliographically 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
Show others...
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
Oskarsson, J. & McGawley, K. (2018). No individual or combined effects of caffeine and beetroot-juice supplementation during submaximal or maximal running. Applied Physiology, Nutrition and Metabolism, 43(7), 697-703
Open this publication in new window or tab >>No individual or combined effects of caffeine and beetroot-juice supplementation during submaximal or maximal running
2018 (English)In: Applied Physiology, Nutrition and Metabolism, ISSN 1715-5312, E-ISSN 1715-5320, Vol. 43, no 7, p. 697-703Article in journal (Refereed) Published
Abstract [en]

Background: Dietary supplements such as caffeine and beetroot juice are used byathletes in an attempt to optimize performance and therefore gain an advantagein competition. Aim: To investigatethe individual and combined effects of caffeine and beetroot-juicesupplementation during submaximal and maximal treadmill running. Methods: Seven males (VO2max:59.0 ± 2.9 mL/kg/min) and two females (VO2max: 53.1 ± 11.4 mL/kg/min)performed a preliminary trial followed by four experimental test sessions,which consisted of two, 5-min submaximal running bouts (at ~ 70% and 80% of VO2max) and a maximal 1-km time-trial (TT) in a laboratory. Participants ingested a 70-ml dose of concentrated beetroot juice containing either 7.3 mmol of nitrate (BR) or no nitrate (PBR) 2.5 hours prior to each test session, theneither 4.8 ± 0.4 (4.3–5.6) mg/kg caffeine (C) or a caffeine placebo (PC)45 minutes before each test session. The four test sessions (BR-C, BR-PC,PBR-C and PBR-PC) were presented in a counter-balancedand double-blind manner. Results: Nosignificant differences were identified between the four interventionsregarding relative VO2, running economy, RER, heart rate (HR) or RPEat the two submaximal intensities (P > 0.05). Moreover, there were nosignificant differences in performance, maximum HR, peak blood lactateconcentration or RPE during the maximal TT when comparing the interventions (P> 0.05). Conclusion: No beneficialeffects of supplementing with typical doses of caffeine, beetroot juice or acombination of the two were observed for physiological, perceptual orperformance responses during submaximal or maximal treadmill running exercise.

Keywords
ergogenic aids, nitrate, performance, time-trial, work economy
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-33511 (URN)10.1139/apnm-2017-0547 (DOI)000436407700007 ()29444414 (PubMedID)2-s2.0-85049190776 (Scopus ID)
Available from: 2018-04-19 Created: 2018-04-19 Last updated: 2018-09-28Bibliographically 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/0000-0002-1273-6061

Search in DiVA

Show all publications