Dataset Information

Physiological Responses to Rifle Carriage During Roller-Skiing in Elite Biathletes.

ABSTRACT: Purpose: This study aimed to investigate the physiological factors affected by rifle carriage during biathlon skiing performance, as well as the sex differences associated with rifle carriage. Methods: Seventeen national- and international-level biathletes (nine females and eight males; age 23.0 ± 3.3 years, V. O2 max 59.4 ± 7.6 mL.kg-1.min-1) performed a submaximal incremental test and a maximal time-trial (TT) using treadmill roller-skiing (gear 3, skating technique) on two occasions separated by at least 48 h. One condition involved carrying the rifle on the back (WR) and the other condition no rifle (NR) and the tests were randomized. Submaximal V. O2, skiing speed at 4 mmol.L-1 of blood lactate (speed@ 4 mmol), gross efficiency (GE), aerobic (MRae), and anaerobic (MRan) metabolic rates, and V. O2 max were determined. Results: Submaximal V. O2 (at all intensities) and GE (16.7 ± 0.9 vs. 16.5 ± 1.1%) were higher for WR compared to NR (p < 0.05), while speed@ 4 mmol was lower (3.1 ± 0.4 vs. 3.3 ± 0.5 m.s-1, p = 0.040). TT performance was improved (4.6 ± 0.4 vs. 4.3 ± 0.4 m.s-1, p < 0.001) and MRan was higher (31.3 ± 8.0 vs. 27.5 ± 6.5 kJ.min-1, p < 0.01) for NR compared to WR, with no difference in V. O2 max or MRae. For skiing WR, TT performance was correlated to speed@ 4 mmol (r = 0.81, p < 0.001), MRan (r = 0.65, p < 0.01), V. O2 max (r = 0.51, p < 0.05), and relative muscle (r = 0.67, p < 0.01) and fat (r = -0.67, p < 0.01) masses. Speed@ 4 mmol together with MRan explained more than 80% of the variation in TT performance (WR 84%, NR 81%). Despite a higher relative mass of the rifle in females compared with males (5.6 ± 0.4 vs. 5.0 ± 0.4% of body mass, p = 0.012), there were no sex differences associated with rifle carriage measured as absolute or relative differences. Conclusion: Rifle carriage in biathlon skiing led to significantly higher physiological demands during submaximal exercise and reduced performance during maximal treadmill roller-skiing compared to NR for both sexes. The most important variables for performance in biathlon treadmill skiing seem to be speed@ 4 mmol combined with MRan, both of which were lower for WR compared to NR. To improve skiing performance in biathlon, improving speed at 4 mmol.L-1 of blood lactate and anaerobic energy delivery while carrying the rifle are recommended.

SUBMITTER: Jonsson Karstrom M

PROVIDER: S-EPMC6951403 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Physiological Responses to Rifle Carriage During Roller-Skiing in Elite Biathletes.

Jonsson Kårström Malin M McGawley Kerry K Laaksonen Marko S MS

Frontiers in physiology 20191219

Purpose: This study aimed to investigate the physiological factors affected by rifle carriage during biathlon skiing performance, as well as the sex differences associated with rifle carriage. Methods: Seventeen national- and international-level biathletes (nine females and eight males; age 23.0 ± 3.3 years, V . O2 max 59.4 ± 7.6 mL.kg-1.min-1) performed a submaximal incremental test and a maximal time-trial (TT) using treadmill roller-s ...[more]

PMID: 31956312

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Project description:Purpose: To develop a method for individual parameter estimation of four hydraulic-analogy bioenergetic models and to assess the validity and reliability of these models' prediction of aerobic and anaerobic metabolic utilization during sprint roller-skiing. Methods: Eleven elite cross-country skiers performed two treadmill roller-skiing time trials on a course consisting of three flat sections interspersed by two uphill sections. Aerobic and anaerobic metabolic rate contributions, external power output, and gross efficiency were determined. Two versions each (fixed or free maximal aerobic metabolic rate) of a two-tank hydraulic-analogy bioenergetic model (2TM-fixed and 2TM-free) and a more complex three-tank model (3TM-fixed and 3TM-free) were programmed into MATLAB. The aerobic metabolic rate (MR ae ) and the accumulated anaerobic energy expenditure (E an,acc ) from the first time trial (STT1) together with a gray-box model in MATLAB, were used to estimate the bioenergetic model parameters. Validity was assessed by simulation of each bioenergetic model using the estimated parameters from STT1 and the total metabolic rate (MR tot ) in the second time trial (STT2). Results: The validity and reliability of the parameter estimation method based on STT1 revealed valid and reliable overall results for all the four models vs. measurement data with the 2TM-free model being the most valid. Mean differences in model-vs.-measured MR ae ranged between -0.005 and 0.016 kW with typical errors between 0.002 and 0.009 kW. Mean differences in E an,acc at STT termination ranged between -4.3 and 0.5 kJ and typical errors were between 0.6 and 2.1 kJ. The root mean square error (RMSE) for 2TM-free on the instantaneous STT1 data was 0.05 kW for MR ae and 0.61 kJ for E an,acc , which was lower than the other three models (all P < 0.05). Compared to the results in STT1, the validity and reliability of each individually adapted bioenergetic model was worse during STT2 with models underpredicting MR ae and overpredicting E an,acc vs. measurement data (all P < 0.05). Moreover, the 2TM-free had the lowest RMSEs during STT2. Conclusion: The 2TM-free provided the highest validity and reliability in MR ae and E an,acc for both the parameter estimation in STT1 and the model validity and reliability evaluation in the succeeding STT2.

Project description:ObjectivesThe aim of this study was to examine the effect of speed on mechanical energy fluctuations and propulsion mechanics in the double-poling (DP) technique of cross-country skiing.MethodsKinematics and dynamics were acquired while fourteen male skiers performed roller-skiing DP on a treadmill at increasing speeds (15, 21 and 27 km∙h-1). Kinetic (Ekin), potential (Epot), and total (Ebody) body mechanical energy and pole power (Ppole) were calculated. Inverse dynamics was used to calculate arm power (Parm). Trunk+leg power (PT+L) was estimated, as was the power associated with body movements perpendicular to goal-direction ([Formula: see text]).ResultsEkin and Epot fluctuated out-of-phase throughout the cycle, at first sight indicating that pendulum-like behaviour occurs partly in DP. However, during the swing phase, the increase in Epot (body heightening) was mainly driven by positive PT+L, while the decrease in Ekin was lost to rolling friction, and during the poling phase, considerable positive Parm generation occurs. Thus, possible exchange between Ekin and Epot seem not to occur as directly and passively as in classic pendulum locomotion (walking). During the poling phase, [Formula: see text]fluctuated out-of-phase with Ppole, indicating a transfer of body energy to Ppole. In this way, power generated by trunk+leg mainly during the swing phase (body heightening) can be used in the poling phase as pole power. At all speeds, negative PT+L occurred during the poling phase, suggesting energy absorption of body energy not transferred to pole power. Thus, DP seem to resemble bouncing ball-like behaviour more than pendulum at faster speeds. Over the cycle, Parm contribution to Ppole (external power) was 63% at 15 km∙h-1 and 66% at 21 and 27 km∙h-1, with the remainder being PT+L contribution.ConclusionsWhen speed increases in level DP, both power production and absorption by trunk+leg actions increase considerably. This enhanced involvement of the legs at faster speeds is likely a prerequisite for effective generation of pole power at high speeds with very short poling times. However, the relative trunk+leg power contribution did not increase at the speeds studied here.

Dataset Information

Physiological Responses to Rifle Carriage During Roller-Skiing in Elite Biathletes.

Publications

Physiological Responses to Rifle Carriage During Roller-Skiing in Elite Biathletes.

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