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  • 1.
    Carlsson, Magnus
    et al.
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science. Sports Medicine Unit, Umeå University, Umeå, Sweden; Dala Sports Academy, Falun, Sweden.
    Carlsson, Tomas
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science. Sports Medicine Unit, Umeå University, Umeå, Sweden; Dala Sports Academy, Falun, Sweden.
    Knutsson, Magnus
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science. Dala Sports Academy, Falun, Sweden.
    Malm, Christer
    Sports Medicine Unit, Umeå University, Umeå, Sweden; Winternet, Boden, Sweden .
    Tonkonogi, Michail
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Oxygen uptake at different intensities and sub‑techniques predicts sprint performance in elite male cross‑country skiers2014In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, no 12, p. 2587-2595Article in journal (Refereed)
    Abstract [en]

    Purpose. To investigate the relationship between sprint-prologue performance (using the classical technique) and the oxygen uptake at the lactate threshold ( V˙O2obla), maximal oxygen uptake ( V˙O 2max), and mean oxygen uptake during double poling ( V˙O 2dp).

    Methods. Eight elite male cross-country skiers [age 24.8 ± 4.8 years, (mean ± SD)] completed two treadmill roller-skiing tests using the diagonal-stride technique and a 60 s double-poling test on a ski-ergometer to determine their V˙O2obla, V˙O 2max, and V˙O 2dp. Performance data were generated from a 1.25 km sprint prologue. Power-function modelling was used to predict the skiers’ race speeds based on the oxygen-uptake variables and body mass.

    Results. There were correlations between the race speed and the absolute expression of the V˙O2obla (r = 0.79, P = 0.021), V˙O 2max (r = 0.86, P = 0.0069), and V˙O 2dp (r = 0.94, P = 0.00062). The following power-function models were established for race-speed prediction: 1.09 · V˙O 2obla0.21, 1.05 · V˙O 2max0.21, and 1.19 · V˙O 2dp0.20; these models explained 60 % (P = 0.024), 73 % (P = 0.0073), and 87 % (P = 0.00073), respectively, of the variance in the race speed. However, body mass did not contribute to any of the models (P = 0.97, 0.88, and 0.21, respectively).

    Conclusions. Oxygen uptake at different intensities and sub-techniques is an indicator of elite male sprint-prologue performance. The absolute expression of the investigated oxygen-uptake variables should be used when evaluating elite male sprint-prologue performances; if skiers oxygen uptake differs by 1 %, their performances will likely differ by 0.2 % in favour of the skier with higher oxygen uptake.

  • 2.
    Carlsson, Magnus
    et al.
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Wahrenberg, Viktor
    Carlsson, Marie S
    Andersson, Rasmus
    Carlsson, Tomas
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Gross and delta efficiencies during uphill running and cycling among elite triathletes.2020In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate the gross efficiency (GE) and delta efficiency (DE) during cycling and running in elite triathletes.

    METHODS: Five male and five female elite triathletes completed two incremental treadmill tests with an inclination of 2.5° to determine their GE and DE during cycling and running. The speed increments between the 5-min stages were 2.4 and 0.6 km h-1 during the cycling and running tests, respectively. For each test, GE was calculated as the ratio between the mechanical work rate (MWR) and the metabolic rate (MR) at an intensity corresponding to a net increase in blood-lactate concentration of 1 mmol l-1. DE was calculated by dividing the delta increase in MWR by the delta increase in MR for each test. Pearson correlations and paired-sample t tests were used to investigate the relationships and differences, respectively.

    RESULTS: There was a correlation between GEcycle and GErun (r = 0.66; P = 0.038; R2 = 0.44), but the correlation between DEcycle and DErun was not statistically significant (r = - 0.045; P = 0.90; R2 = 0.0020). There were differences between GEcycle and GErun (t = 80.8; P < 0.001) as well as between DEcycle and DErun (t = 27.8; P < 0.001).

    CONCLUSIONS: Elite triathletes with high GE during running also have high GE during cycling, when exercising at a treadmill inclination of 2.5°. For a moderate uphill incline, elite triathletes are more energy efficient during cycling than during running, independent of work rate.

  • 3.
    Carlsson, Tomas
    et al.
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Wedholm, Lars
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Nilsson, Johnny
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    Carlsson, Magnus
    Dalarna University, School of Education, Health and Social Studies, Sport and Health Science.
    The effects of strength training versus ski-ergometer training on double-poling capacity of elite junior cross-country skiers2017In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 117, no 8, p. 1523-1532Article in journal (Refereed)
    Abstract [en]

    Purpose

    To compare the effects of strength training versus ski-ergometer training on double-poling gross efficiency (GE), maximal speed (Vmax), peak oxygen uptake (V&#x02D9;O2peak" role="presentation" style="box-sizing: border-box; display: inline-table; line-height: normal; letter-spacing: 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;">V˙O2peakV˙O2peak) for elite male and female junior cross-country skiers.

    Methods

    Thirty-three elite junior cross-country skiers completed a 6-week training-intervention period with two additional 40-min training sessions per week. The participants were matched in pairs and within each pair randomly assigned to either a strength-training group (STR) or a ski-ergometer-training group (ERG). Before and after the intervention, the participants completed three treadmill roller-skiing tests to determine GE, Vmax, and V&#x02D9;O2peak" role="presentation" style="box-sizing: border-box; display: inline-table; line-height: normal; letter-spacing: 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;">V˙O2peakV˙O2peak. Mixed between-within subjects analysis of variance (ANOVA) was conducted to evaluate differences between and within groups. Paired samples t tests were used as post hoc tests to investigate within-group differences.

    Results

    Both groups improved their Vmax and V&#x02D9;O2peak" role="presentation" style="box-sizing: border-box; display: inline-table; line-height: normal; letter-spacing: 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;">V˙O2peakV˙O2peak expressed absolutely (all P < 0.01). For the gender-specific sub-groups, it was found that the female skiers in both groups improved both Vmax and V&#x02D9;O2peak" role="presentation" style="box-sizing: border-box; display: inline-table; line-height: normal; letter-spacing: 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;">V˙O2peakV˙O2peak expressed absolutely (all P < 0.05), whereas the only within-group differences found for the men were improvements of Vmax in the STR group. No between-group differences were found for any of the investigated variables.

    Conclusions

    Physiological and performance-related variables of importance for skiers were improved for both training regimes. The results demonstrate that the female skiers’ physiological adaptations to training, in general, were greater than those of the men. The magnitude of the physiological adaptations was similar for both training regimes.

  • 4.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tinmark, Fredrik
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halvorsen, Kjartan
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 6, p. 1385-1394Article in journal (Refereed)
    Abstract [en]

    This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h−1. In a second set of recordings, horizontal resistance was added by weights (0.4–1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h−1. Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (±SD) horizontal force components ranged between 1.7 (±1.3) and 2.8 (±1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (±0.6) and 4.0 (±1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

  • 5.
    Rosdahl, Hans
    et al.
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lindberg, Thomas
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Edin, Fredrik
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    The Moxus Modular metabolic sustem evaluated with two sensors for ventilation against the Douglas bag method2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 5, p. 1353-1367Article in journal (Refereed)
    Abstract [en]

    This study evaluated the Moxus metabolic system with the Douglas bag method (DBM) as criterion. Reliability and validity were investigated in a wide range of ventilation and oxygen uptake and two sensors for determining ventilation were included. Thirteen well-trained athletes participated in one pre-test and four tests for data collection, exercising on a cycle ergometer at five submaximal powers (50-263 W) and at [Formula: see text]. Gas exchange variables were measured simultaneously using a serial setup with data collected on different days in an order randomized between Moxus with pneumotachometer (MP) and turbine flowmeter (MT) sensors for ventilation. Reliability with both sensors was comparable to the DBM. Average CV (%) of all exercise intensities were with MP: 3.0 ± 1.3 for VO(2), 3.8 ± 1.5 for VCO(2), 3.1 ± 1.2 for the respiratory exchange ratio (RER) and 4.2 ± 0.8 for V (E). The corresponding values with MT were: 2.7 ± 0.3 for VO(2), 4.7 ± 0.4 for VCO(2), 3.3 ± 0.9 for RER and 4.8 ± 1.4 for V (E). Validity was acceptable except for small differences related to the determination of ventilation. The relative differences in relation to DBM at the powers including [Formula: see text] were similar for both sensors with the ranges being: +4 to -2 % for V (E), +5 to -3 % for VO(2) and +5 to -4 % for VCO(2) while RER did not differ at any power. The Moxus metabolic system shows high and adequate reliability and reasonable validity over a wide measurement range. At a few exercise levels, V (E) differed slightly from DBM, resulting in concomitant changes in VO(2) and VCO(2).

  • 6. Sahlin, Kent
    et al.
    Tonkonogi, Michail
    Dalarna University, School of Health and Social Studies, Medical Science.
    Söderlund, Karin
    Plasma hypoxanthine and ammonia in humans during prolonged exercise.1999In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 80, p. 417-422Article in journal (Refereed)
    Abstract [en]

    In this study we examined the time course of changes in the plasma concentration of oxypurines [hypoxanthine (Hx), xanthine and urate] during prolonged cycling to fatigue. Ten subjects with an estimated maximum oxygen uptake ( V?O 2max) of 54 (range 47–67) ml?·?kg -1?·?min -1 cycled at [mean?(SEM)] 74?(2)% of V?O 2max until fatigue [79?(8) min]. Plasma levels of oxypurines increased during exercise, but the magnitude and the time course varied considerably between subjects. The plasma concentration of Hx ([Hx]) was 1.3?(0.3)?µmol/l at rest and increased eight fold at fatigue. After 60?min of exercise plasma [Hx] was >10?µmol/l in four subjects, whereas in the remaining five subjects it was <5?µmol/l. The muscle contents of total adenine nucleotides (TAN?=?ATP+ADP+AMP) and inosine monophosphate (IMP) were measured before and after exercise in five subjects. Subjects with a high plasma [Hx] at fatigue also demonstrated a pronounced decrease in muscle TAN and increase in IMP. Plasma [Hx] after 60?min of exercise correlated significantly with plasma concentration of ammonia ([NH 3], r?=?0.90) and blood lactate ( r?=?0.66). Endurance, measured as time to fatigue, was inversely correlated to plasma [Hx] at 60?min ( r?=?-0.68, P?3] or blood lactate. It is concluded that during moderate-intensity exercise, plasma [Hx] increases, but to a variable extent between subjects. The present data suggest that plasma [Hx] is a marker of adenine nucleotide degradation and energetic stress during exercise. The potential use of plasma [Hx] to assess training status and to identify overtraining deserves further attention.

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