High-frequency fatigue after alpine slalom skiing

Tomažin, Katja; Dolenec, Aleš; Strojnik, Vojko

doi:10.1007/s00421-008-0685-y

Cited by 12 publications

(13 citation statements)

References 27 publications

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“…The hip angle was fixed at 110°. Subjects sat in the isometric knee torque measuring device equipped with a force transducer (MES, Maribor, Slovenia) (Tomazin et al, 2008). The back was supported and the hips were firmly fixed, the rotational axis of the dynamometer was visually aligned to the rotational axis of the knee (i. e., lateral femoral epicondyle) and the lower leg was attached to the dynamometer lever arm above the ankle joint (i. e., lateral malleolus).…”

Section: Methodsmentioning

confidence: 99%

The Relationship Between the Lower-Body Muscular Profile and Swimming Start Performance

García-Ramos

Tomažin

Feriche

et al. 2016

Journal of Human Kinetics

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This study aimed to examine the correlation of different dry land strength and power tests with swimming start performance. Twenty international level female swimmers (age 15.3 ± 1.6 years, FINA point score 709.6 ± 71.1) performed the track freestyle start. Additionally, dry land tests were conducted: a) squat (SJ) and countermovement jumps (CMJ), b) squat jumps with additional resistance equivalent to 25, 50, 75 and 100% of swimmers’ body weight [BW]), and c) leg extension and leg flexion maximal voluntary isometric contractions. Correlations between dry land tests and start times at 5, 10 and 15 m were quantified through Pearson’s linear correlation coefficients (r). The peak bar velocity reached during the jumps with additional resistance was the variable most correlated to swimming start performance (r = -0.57 to -0.66 at 25%BW; r = -0.57 to -0.72 at 50%BW; r = -0.59 to -0.68 at 75%BW; r = -0.50 to - 0.64 at 100%BW). A few significant correlations between the parameters of the SJ and the CMJ with times of 5 and 10 m were found, and none with the isometric variables. The peak velocity reached during jumps with external loads relative to BW was found a good indicator of swimming start performance.

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Section: Methodsmentioning

confidence: 99%

The Relationship Between the Lower-Body Muscular Profile and Swimming Start Performance

García-Ramos

Tomažin

Feriche

et al. 2016

Journal of Human Kinetics

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“…Reportedly, skiing-induced fatigue is manifested by decreases in hamstring and quadriceps eccentric torque for 1–24 h following a 4-h skiing session ( Koller et al, 2015 ). Hence, skiing-induced fatigue alters force production capacity and electromyographic (EMG) activity in the lower extremities ( Kröll et al, 2005 , 2011 ; Ushiyama et al, 2005 ; Akutsu et al, 2008 ; Tomazin et al, 2008 ; Kiryu et al, 2011 ). Neuromuscular consequences of fatigue development for the vastus lateralis (VL) muscle also include a decline in mean power frequency in the first half of a 1–2 min ski run ( Ushiyama et al, 2005 ) and the presence of high-frequency fatigue after ∼45 s of slalom ( Tomazin et al, 2008 ).…”

Section: Introductionmentioning

confidence: 99%

Hypoxia and Fatigue Impair Rapid Torque Development of Knee Extensors in Elite Alpine Skiers

et al. 2018

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This study examined the effects of acute hypoxia on maximal and explosive torque and fatigability in knee extensors of skiers. Twenty-two elite male alpine skiers performed 35 maximal, repeated isokinetic knee extensions at 180°s-1 (total exercise duration 61.25 s) in normoxia (NOR, FiO2 0.21) and normobaric hypoxia (HYP, FiO2 0.13) in a randomized, single-blind design. Peak torque and rate of torque development (RTD) from 0 to 100 ms and associated Vastus Lateralis peak EMG activity and rate of EMG rise (RER) were determined for each contraction. Relative changes in deoxyhemoglobin concentration of the VL muscle were monitored by near-infrared spectroscopy. Peak torque and peak EMG activity did not differ between conditions and decreased similarly with fatigue (p < 0.001), with peak torque decreasing continuously but EMG activity decreasing significantly after 30 contractions only. Compared to NOR, RTD, and RER values were lower in HYP during the first 12 and 9 contractions, respectively (both p < 0.05). Deoxyhemoglobin concentration during the last five contractions was higher in HYP than NOR (p = 0.050) but the delta between maximal and minimal deoxyhemoglobin for each contraction was similar in HYP and NOR suggesting a similar muscle O2 utilization. Post-exercise heart rate (138 ± 24 bpm) and blood lactate concentration (5.8 ± 3.1 mmol.l-1) did not differ between conditions. Arterial oxygen saturation was significantly lower (84 ± 4 vs. 98 ± 1%, p < 0.001) and ratings of perceived exertion higher (6 ± 1 vs. 5 ± 1, p < 0.001) in HYP than NOR. In summary, hypoxia limits RTD via a decrease in neural drive in elite alpine skiers undertaking maximal repeated isokinetic knee extensions, but the effect of hypoxic exposure is negated as fatigue develops. Isokinetic testing protocols for elite alpine skiers should incorporate RTD and RER measurements as they display a higher sensitivity than peak torque and EMG activity.

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“…Our group (18) showed that low-to high-frequency force ratio measured during stimulation trains with submaximal EMS as commonly used (see for instance Refs. 4,6,12,26,28) provide similar assessment of fatigue after exercise compared with supramaximal ENS. Nevertheless, because most magnetic stimulators do not deliver stimulation trains, some authors evaluated the use of paired stimulations as a surrogate for stimulation trains to assess the relative contribution of low and high frequencies to force output as well as induction and recovery of contractile fatigue.…”

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“…Moreover, we compared the T2 10:100 ratio obtained with paired stimuli via ENS, MNS, and EMS to the Ftet 10:100 ratio obtained with tetanic quadriceps stimulation via submaximal EMS as commonly performed in the literature (e.g., Refs. 4,6,12,26,28). We hypothesized that 1) ENS and MNS would provide similar assessment of the quadriceps function in both unfatigued and fatigued states, and 2) T2 10:100 ratio would provide similar information regarding quadriceps low-frequency fatigue compared with Ftet 10:100 ratio.…”

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Comparison of electrical and magnetic stimulations to assess quadriceps muscle function

Vergès¹,

Maffiuletti²,

Kerhervé³

et al. 2009

Journal of Applied Physiology

130

115

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This study aimed to 1) compare electrical and magnetic stimulations for quadriceps muscle function assessment, and 2) ascertain whether the ratios of the second twitch elicited by supramaximal electrical and magnetic femoral nerve stimulation at 10 and 100 Hz (T2(10:100)) and the total twitch force elicited by the same types of stimulations (Fpaired(10:100)) are equivalent to the standard low- to high-frequency force ratio associated with submaximal electrical tetanic stimulations (Ftet(10:100)). Quadriceps force and vastus lateralis EMG were recorded at rest (n = 21 subjects), immediately after, and 30 min after a 30-min downhill run (n = 10) when 1) supramaximal electrical nerve stimulation (ENS), 2) magnetic nerve stimulation (MNS) and 3) submaximal electrical muscle stimulation (EMS) were delivered in random order at 1 (single stimulation), 10, and 100 Hz (paired stimulations). Ten- and 100-Hz 500-ms tetani were also evoked with EMS to determine Ftet(10:100). Before exercise, contractile properties with single and paired stimulations were similar for ENS and MNS (all intraclass correlation coefficients k > 0.90), but smaller for EMS (P < 0.001). M-wave characteristics were also similar for ENS and MNS (all k > 0.90). After exercise, changes in all parameters did not differ between methods. With fatigue, the changes in Ftet(10:100) were inconsistently correlated with the changes in T2(10:100) (r(2) = 0.24-0.73, P = 0.002-0.15) but better correlated with the changes in Fpaired(10:100) (immediately after exercise: r(2) = 0.80-0.83, P < 0.001; 30 min after exercise: r(2) = 0.46-0.82, P = 0.001-0.03). We conclude that ENS and MNS provide similar quadriceps muscle function assessment, while Fpaired(10:100) is a better index than T2(10:100) of low- to high-frequency fatigue of the quadriceps in vivo.

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High-frequency fatigue after alpine slalom skiing

Cited by 12 publications

References 27 publications

The Relationship Between the Lower-Body Muscular Profile and Swimming Start Performance

The Relationship Between the Lower-Body Muscular Profile and Swimming Start Performance

Hypoxia and Fatigue Impair Rapid Torque Development of Knee Extensors in Elite Alpine Skiers

Comparison of electrical and magnetic stimulations to assess quadriceps muscle function

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