title: Changes in technique and efficiency after high-intensity exercise in cross-country skiers.
abstract: This study investigated changes in technique and efficiency after high-intensity exercise to exhaustion in elite cross-country skiers. Twelve elite male skiers completed 4 min submaximal exercise before and after a high-intensity incremental test to exhaustion with the G3 skating technique on a 5% inclined roller-ski treadmill. Kinematics and kinetics were monitored by instrumented roller skis, work rate was calculated as power against roller friction and gravity, aerobic metabolic cost was determined from gas exchange, and blood lactate values indicated the anaerobic contribution. Gross efficiency was the work rate divided by aerobic metabolic rate. A recovery period of 10 min between the incremental test and the posttest was included to allow the metabolic values to return to baseline. Changes in neuromuscular fatigue in upper and lower limbs before and after the incremental test were indicated by peak power in concentric bench press and squat-jump height. From pretest to posttest, cycle length decreased and cycle rate increased by approximately 5% (P < 0.001), whereas the amount of ski forces did not change significantly. Oxygen uptake increased by 4%, and gross efficiency decreased from 15.5% ± 0.7% to 15.2% ± 0.5% from pretest to posttest (both P < .02). Correspondingly, blood lactate concentration increased from 2.4 ± 1.0 to 6.2 ± 2.5 mmol/L (P < .001). Bench-press and squat-jump performance remained unaltered. Elite cross-country skiers demonstrated a less efficient technique and shorter cycle length during submaximal roller-ski skating after high-intensity exercise. However, there were no changes in ski forces or peak power in the upper and lower limbs that could explain these differences.
authors: Dept. of Human Movement Science, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Christina
authors: C
authors: Åsan Grasaas
authors: Gertjan
authors: G
authors: Ettema
authors: Ann Magdalen
authors: AM
authors: Hegge
authors: Knut
authors: K
authors: Skovereng
authors: Øyvind
authors: Ø
authors: Sandbakk
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D012865:Skiing / Q000502:physiology*
chemical_list: D019344:Lactic Acid