Thomas Losnegard

The effect of heavy strength training on muscle mass and physical performance in elite cross country skiers

Aim: To investigate the effect of supplementing high‐volume endurance training with heavy strength training on muscle adaptations and physical performance in elite cross country skiers. Eleven male (18–26 years) and eight female (18–27 years) were assigned to either a strength group (STR) (n=9) or a control group (CON) (n=10). STR performed strength training twice a week for 12 weeks in addition to their normal endurance training. STR improved 1 repetition maximum (RM) for seated pull‐down and half squat (19±2% and 12±2%, respectively), while no change was observed in CON. Cross‐sectional area (CSA) increased in m. triceps brachii for both STR and CON, while there was no change in the m. quadriceps CSA. VO2max during skate‐rollerskiing increased in STR (7±1%), while VO2max during running was unchanged. No change was observed in energy consumption during rollerskiing at submaximal intensities. Double‐poling performance improved more for STR than for CON. Both groups showed a similar improvement in rollerski time‐trial performance. In conclusion, 12 weeks of supplemental heavy strength training improved the strength in leg and upper body muscles, but had little effect on the muscle CSA in thigh muscles. The supplemental strength training improved both VO2max during skate‐rollerskiing and double‐poling performance.

Muscle use during double poling evaluated by positron emission tomography

Due to the complexity of movement in cross-country skiing (XCS), the muscle activation patterns are not well elucidated. Previous studies have applied surface electromyography (SEMG); however, recent gains in three-dimensional (3D) imaging techniques such as positron emission tomography (PET) have rendered an alternative approach to investigate muscle activation. The purpose of the present study was to examine muscle use during double poling (DP) at two work intensities by use of PET. Eight male subjects performed two 20-min DP bouts on separate days. Work intensity was ∼ 53 and 74% of peak oxygen uptake (Vo(2peak)), respectively. During exercise 188 ± 8 MBq of [(18)F]fluorodeoxyglucose ([(18)F]FDG) was injected, and subsequent to exercise a full-body PET scan was conducted. Regions of interest (ROI) were defined within 15 relevant muscles, and a glucose uptake index (GUI) was determined for all ROIs. The muscles that span the shoulder and elbow joints, the abdominal muscles, and hip flexors displayed the greatest GUI during DP. Glucose uptake did not increase significantly from low to high intensity in most upper body muscles; however, an increased GUI (P < 0.05) was seen for the knee flexor (27%) and extensor muscles (16%), and for abdominal muscles (21%). The present data confirm previous findings that muscles of the upper limb are the primary working muscles in DP. The present data further suggest that when exercise intensity increases, the muscles that span the lumbar spine, hip, and knee joints contribute increasingly. Finally, PET provides a promising alternative or supplement to existing methods to assess muscle activation in complex human movements.

Anaerobic Capacity as a Determinant of Performance in Sprint Skiing

PURPOSE As cross-country sprint competitions rely on maximal-effort durations of ∼3 min, a significant anaerobic energy contribution is expected. Anaerobic energy production during supramaximal exercise has been estimated in different sports from the accumulated oxygen deficit (ΣO₂ deficit) but, to date, not in cross-country skiing. Therefore, this study investigated the relative contribution of the aerobic and anaerobic energy systems to performance in ski skating sprint time trials using V1 and V2 techniques. METHODS Twelve elite senior male cross-country skiers participated in the study (24 ± 3 yr, 183 ± 5 cm, 79 ± 7 kg, V˙O(2max) = 72 ± 3 mL·kg⁻¹·min⁻¹ or 5.7 ± 0.5 L·min⁻¹). Three submaximal trials (4°-6°), one V˙O(2max) test (8°), and one performance test (7°, 600 m) were performed both in the V1 and in the V2 ski skating technique on a roller ski treadmill. RESULTS ΣO₂ deficit was ∼60 mL·kg⁻¹ and contributed to ∼26% of the total energy release during the ∼170-s time trials. Low to moderate correlations (r = 0.09-0.51) were found between O₂ cost of skiing, fractional utilization of V˙O(2peak), fractional utilization, and 600-m time. However, a moderate to strong correlation was found between ΣO₂ deficit and 600-m time in both the V1 (r = -0.75) and the V2 tests (r = -0.64) (both P < 0.05). No significant differences were found between techniques according to 600-m time or physiological responses. CONCLUSIONS The contribution from anaerobic energy systems was ∼26% and seemed independent of technique. In a group of elite skiers, the difference in roller ski treadmill sprint performance is more related to differences in anaerobic capacity than maximal aerobic power and O₂ cost.

Seasonal Variations in V[combining Dot Above]o2max, O2-cost, O2-deficit, and Performance in Elite Cross-country Skiers

Abstract Losnegard, T, Myklebust, H, Spencer, M, and Hallén, J. Seasonal variations in V[Combining Dot Above]O2max, O2-cost, O2-deficit, and performance in elite cross-country skiers. J Strength Cond Res 27(7): 1780–1790, 2013—Long-term effects of training are important information for athletes, coaches, and scientists when associating changes in physiological indices with changes in performance. Therefore, this study monitored changes in aerobic and anaerobic capacities and performance in a group of elite cross-country skiers during a full sport season. Thirteen men (age, 23 ± 2 years; height, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 roller ski skating V[Combining Dot Above]O2max, 79.3 ± 4.4 ml·kg−1·min−1 or 6.0 ± 0.5 L·min−1) were tested during the early, middle, and late preparation phase: June (T1), August (T2), and October (T3); during the competition phase: January/February (T4); and after early precompetition phase: June (T5). O2-cost during submaximal efforts, V[Combining Dot Above]O2peak, accumulated oxygen deficit (&Sgr;O2-deficit), and performance during a 1,000-m test were determined in the V2 ski skating technique on a roller ski treadmill. Subjects performed their training on an individual basis, and detailed training logs were categorized into different intensity zones and exercise modes. Total training volume was highest during the summer months (early preseason) and decreased toward and through the winter season, whereas the volume of high-intensity training increased (all p < 0.05). There was a significant main effect among testing sessions for 1,000 m time, O2-cost, and &Sgr;O2-deficit (Cohen’s d effect size; ES = 0.63–1.37, moderate to large, all p < 0.05). In general, the changes occurred between T1 and T3 with minor changes in the competitive season (T3 to T4). No significant changes were found in V[Combining Dot Above]O2peak across the year (ES = 0.17, trivial). In conclusion, the training performed by elite cross-country skiers induced no significant changes in V[Combining Dot Above]O2peak but improved performance, O2-cost, and &Sgr;O2-deficit.

Physiological Differences Between Sprint- and Distance-Specialized Cross-Country Skiers

PURPOSE Sprint- (≤1.8 km) and distance-skiing (≥15 km) performance rely heavily on aerobic capacity. However, in sprint skiing, due to the ~20% higher speed, anaerobic capacity contributes significantly. This study aimed to identify the possible anthropometric and physiological differences between elite male sprint and distance skiers. METHODS Six sprint and 7 distance international-level cross-country skiers completed testing using the V2 skating technique on a roller-ski treadmill. Measurements included submaximal O2 cost (5°, 3 m/s) and a 1000-m time trial (6°, >3.25 m/s) to assess VO2peak and accumulated oxygen (σO2) deficit. RESULTS The groups displayed similar O2 cost during the submaximal load. The sprint skiers had a higher σO2 deficit (79.0 ± 11.3 vs 65.7 ± 7.5·mL/kg, P = .03, ES = 1.27) and VO2peak in absolute values (6.6 ± 0.5 vs 6.0 ± 0.5 L/ min, P = .04, ES =1.23), while VO2peak relative to body mass was lower than in the distance skiers (76.4 ± 4.4 vs 83.0 ± 3.2 mL · kg-1 · min-1, P = .009, ES = 1.59). The sprint skiers were heavier than the distance skiers (86.6 ± 6.1 vs 71.8 ± 7.2 kg, P = .002, ES = 2.07), taller (186 ± 5 vs 178 ± 7 cm, P = .04, ES = 1.25), and had a higher body-mass index (24.9 ± 0.8 vs 22.5 ± 1.3 kg/m2, P = .003, ES = 2.05). CONCLUSION The elite male sprint skiers showed different anthropometric and physiological qualities than the distance skiers, with these differences being directly related to body mass.

Differences in V1 and V2 ski skating techniques described by accelerometers

The aims of the study were to describe the differences between the ski skating techniques V1 and V2 and evaluate reproducibility in complex cyclic hip movements measured by accelerometers. Fourteen elite senior male cross‐country skiers rollerskied twice for 1 min (V1 and V2) at 4° inclination and 3 m/s. Tests were repeated after 20 min and again 4 months later. Five triaxial accelerometers were attached to the subjects hip (os sacrum), poles, and ski boots. Post‐processing included transforming to an approximately global coordinate system, normalization for cycle time, double integration for displacement, and revealing temporal patterns. Different acceleration patterns between techniques and large correlation coefficients (Pearsons r = 0.6–0.9) between repeated trials were seen for most parameters. In V2, the hip was lowered [−10.9 (1.2) cm], whereas in V1, the hip was elevated [4.8 (1.5) cm] during the pole thrust. In conclusion, V2 but not V1 showed similarities to double poling in the way that potential energy is gained between poling strokes and transferred to propulsion during the poling action. Elite skiers reproduce their own individual patterns. One triaxial accelerometer on the lower back can distinguish techniques and might be useful in field research as well as in providing individual feedback on daily technique training.

Variability and Predictability of Performance Times of Elite Cross-Country Skiers

UNLABELLED Analyses of elite competitive performance provide useful information for research and practical applications. PURPOSE Here the authors analyze performance times of cross-country skiers at international competitions (World Cup, World Championship, and Olympics) in classical and free styles of womens and mens distance and sprint events, each with a total of 410-569 athletes competing in 1-44 races at 15-25 venues from seasons 2002 to 2011. METHODS A linear mixed model of race times for each event provided estimates of within-athlete race-to-race variability expressed as a coefficient of variation (CV) after adjustment for fixed or random effects of snow conditions, altitude, race length, and competition terrain. RESULTS Within-athlete variability was similar for men and women over various events for all athletes (CV of 1.5-1.8%) and for the annual top-10 athletes (1.1-1.4%). Observed effects of snow conditions and altitude on mean time were substantial (~2%) but mostly unclear, owing to large effects of terrain (CV of 4-10% in top-10 analyses). Predictability of performance was extremely high for all athletes (intraclass correlations of .90-.96) but only trivial to poor for top-10 athletes (men .00-.03, women .03-.35). CONCLUSION The race-to-race variability of top-ranked skiers is similar to that of other elite endurance athletes. Estimates of the smallest worthwhile performance enhancement (0.3× within-athlete variability) will help researchers and practitioners evaluate strategies affecting performance of elite skiers.

An Analysis of the Pacing Strategies Adopted by Elite Cross-Country Skiers.

Abstract Losnegard, T, Kjeldsen, K, and Skattebo, Ø. An analysis of the pacing strategies adopted by elite cross-country skiers. J Strength Cond Res 30(11): 3256–3260, 2016—Understanding the pacing strategies used by the most successful skiers may provide insight into the most desirable pacing approach in cross-country (XC) skiing. This study examined the pacing strategies adopted by male and female XC skiers of different performance standards during 10 and 15 km races in World Cup, World Championships, and Olympic events. Analyses were performed on races involving 5 km laps in the mens 15 km (number of races = 22) and the womens 10 km (n = 14) individual start races (classic and freestyle) from season 2002/2003 to season 2013/2014. Final rank and lap times for the 40 top finishers in each race were analyzed. Both sexes demonstrated a positive pacing pattern shown by a decline in velocity from the first to the last lap (men: 6.76 ± 0.43 m·s−1 vs. 6.47 ± 0.46 m·s−1; p < 0.001; women: 6.0 ± 0.47 m·s−1 vs. 5.87 ± 0.53 m·s−1; p < 0.001). For the men, slower skiers (final ranking 21st–30th and 31st–40th) were characterized by a quick start relative to their average velocity, with a greater decrease during the race compared with the fastest skiers (1st–10th) (p = 0.007 and p < 0.001, respectively). For the women, no group differences in pacing strategy were found. In conclusion, this study shows that the pacing strategy indicates the standard of elite male XC skiers. Examining the pacing strategies of the best male performers suggests that lower-performing male skiers should consider a more even pacing strategy to improve their performance.

The Physiological Capacity of the World's Highest Ranked Female Cross-country Skiers.

Supplemental digital content is available in the text.

No differences in O2-cost between V1 and V2 skating techniques during treadmill roller skiing at moderate to steep inclines.

Abstract Losnegard, T, Myklebust, H, and Hallén, J. No differences in O2-cost between V1 and V2 skating techniques during treadmill roller skiing at moderate to steep inclines. J Strength Cond Res 26(5): 1340–1347, 2012—Elite crosscountry skiers use both the V1 and V2 techniques on moderate and steep inclines despite previous studies suggesting that the V1 technique is superior in terms of lower O2-cost and better performance on these inclines. However, this has not been studied in elite athletes, and therefore, the aim of this study was to compare O2-cost in these 2 main ski skating techniques in a group of 14 elite male crosscountry skiers (age: 24 ± 3 years, height: 184 ± 6 cm, weight: 79 ± 7 kg, V1 V[Combining Dot Above]O2max: 71.8 ± 3.5 ml·kg−1·min−1). With both techniques, the athletes performed submaximal trials for the determination of O2-cost on a roller ski treadmill at 4, 5, and 6° (3 m·s−1) and maximal trials at 8° (≥3 m·s−1) for the determination of V[Combining Dot Above]O2max. Video-based kinematic analyses on cycle length and cycle rate (CR) were performed to unravel if there was any relation between these variables and O2-cost. No significant differences in O2-cost or V[Combining Dot Above]O2max between techniques were found. However, large and significant individual variations in physiological response were observed. V2 had a longer cycle length and lower CR than V1 did. No significant correlation was found between CR and O2-cost. This study shows that both V1 and V2 are appropriate techniques for optimizing O2-cost on moderate to steep inclines in elite skiers. However, individual variation suggests that ski skating performance on moderate to steep inclines may be determined by technique preferences of the athletes.