scholarly journals Pacing Strategy, Muscle Fatigue, and Technique in 1500-m Speed-Skating and Cycling Time Trials

2016 ◽  
Vol 11 (3) ◽  
pp. 337-343 ◽  
Author(s):  
Inge K. Stoter ◽  
Brian R. MacIntosh ◽  
Jared R. Fletcher ◽  
Spencer Pootz ◽  
Inge Zijdewind ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Blood Lactate ◽  
National Level ◽  
Time Trial ◽  
Voluntary Activation ◽  
Slow Start ◽  
Speed Skating ◽  
Fast Start ◽  
Start Trial ◽  
Cycling Time

Purpose:To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500-m speed-skating and cycling time trials when a faster or slower start is instructed.Methods:Nine speed skaters and 9 cyclists, all competing at regional or national level, performed two 1500-m time trials in their sport. Athletes were instructed to start faster than usual in 1 trial and slower in the other. Mean velocity was measured per 100 m. Blood lactate concentrations were measured. Maximal voluntary contraction (MVC), voluntary activation (VA), and potentiated twitch (PT) of the quadriceps muscles were measured to estimate central and peripheral contributions to muscle fatigue. In speed skating, knee, hip, and trunk angles were measured to evaluate technique.Results:Cyclists showed a more explosive start than speed skaters in the fast-start time trial (cyclists performed first 300 m in 24.70 ± 1.73 s, speed skaters in 26.18 ± 0.79 s). Both trials resulted in reduced MVC (12.0% ± 14.5%), VA (2.4% ± 5.0%), and PT (25.4% ± 15.2%). Blood lactate concentrations after the time trial and the decrease in PT were greater in the fast-start than in the slow-start trial. Speed skaters showed higher trunk angles in the fast-start than in the slow-start trial, while knee angles remained similar.Conclusions:Despite similar instructions, behavioral adaptations in pacing differed between the 2 sports, resulting in equal central and peripheral contributions to muscle fatigue in both sports. This provides evidence for the importance of neurophysiological aspects in the regulation of pacing. It also stresses the notion that optimal pacing needs to be studied sport specifically, and coaches should be aware of this.

scholarly journals Characterization of performance fatigability during a self-paced exercise

2019 ◽  
Vol 127 (3) ◽  
pp. 838-846 ◽  
Author(s):  
Rafael de Almeida Azevedo ◽  
Ramon Cruz ◽  
Patrícia Couto ◽  
Marcos David Silva-Cavalcante ◽  
Daniel Boari ◽  
...  
Keyword(s):  
Time Course ◽  
Muscle Activation ◽  
Contractile Function ◽  
Time Trial ◽  
Peak Torque ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Electromyographic Activity ◽  
Cycling Time Trial ◽  
Fast Start

Pacing during a high-intensity cycling time trial (TT) appears to prevent premature task failure, but the performance fatigability during a self-paced exercise is currently unknown. Therefore, the current study characterized the time course of performance fatigability during a 4-km TT. Eleven male cyclists performed three separated TTs in a crossover, counterbalanced design. The TTs lasted until the end of the fast-start (FS; 600 ± 205 m), even-pace (EP; 3,600 ± 190 m), and end-spurt (ES; 4,000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVCs), whereas the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [e.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically evoked contractions performed before and 1 min after each specific part of the trial. Gas exchange, power output (PO), and electromyographic activity (EMG) were also recorded. EMG/PO showed an abrupt increase followed by a continuous decrease toward the end of FS, resulting in a drop in IMVC (−12%), VA (−8%), and TwPt (−23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA, or TwPt (−12%, −6%, and −22%, respectively). EMG/PO increased abruptly during the ES, but there was no change in IMVCs, VA, or TwPt (−13%, −8%, and −26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop in contractile function and muscle activation at the beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES). NEW & NOTEWORTHY The time course of performance fatigability throughout a self-paced exercise is currently unknown. The results showed that a large amount of muscle activation and contractile function impairments are attained early on a self-paced exercise (first ∼15% of the total time trial distance) and maintained throughout the test. This novel finding characterizes the performance fatigability from a contractile function and muscle activation perspective, which brings new insights for future studies focused on real-world exercise training and competition.

scholarly journals Summated Hazard Score as a Powerful Predictor of Fatigue in Relation to Pacing Strategy

2021 ◽  
Vol 18 (4) ◽  
pp. 1984
Author(s):  
Sylvia Binkley ◽  
Carl Foster ◽  
Cristina Cortis ◽  
Jos J. de Koning ◽  
Christopher Dodge ◽  
...  
Keyword(s):  
Perceived Exertion ◽  
Time Trial ◽  
Rating Of Perceived Exertion ◽  
Secondary Outcome ◽  
Outcome Variable ◽  
Start Time ◽  
Slow Start ◽  
Pacing Strategy ◽  
Secondary Outcome Variable ◽  
Fast Start

During competitive events, the pacing strategy depends upon how an athlete feels at a specific moment and the distance remaining. It may be expressed as the Hazard Score (HS) with momentary HS being shown to provide a measure of the likelihood of changing power output (PO) within an event and summated HS as a marker of how difficult an event is likely to be perceived to be. This study aimed to manipulate time trial (TT) starting strategies to establish whether the summated HS, as opposed to momentary HS, will improve understanding of performance during a simulated cycling competition. Seven subjects (peak PO: 286 ± 49.7 W) performed two practice 10-km cycling TTs followed by three 10-km TTs with imposed PO (±5% of mean PO achieved during second practice TT and a self-paced TT). PO, rating of perceived exertion (RPE), lactate, heart rate (HR), HS, summated HS, session RPE (sRPE) were collected. Finishing time and mean PO for self-paced (time: 17.51 ± 1.41 min; PO: 234 ± 62.6 W), fast-start (time: 17.72 ± 1.87 min; PO: 230 ± 62.0 W), and slow-start (time: 17.77 ± 1.74 min; PO: 230 ± 62.7) TT were not different. There was a significant interaction between each secondary outcome variable (PO, RPE, lactate, HR, HS, and summated HS) for starting strategy and distance. The evolution of HS reflected the imposed starting strategy, with a reduction in PO following a fast-start, an increased PO following a slow-start with similar HS during the last part of all TTs. The summated HS was strongly correlated with the sRPE of the TTs (r = 0.88). The summated HS was higher with a fast start, indicating greater effort, with limited time advantage. Thus, the HS appears to regulate both PO within a TT, but also the overall impression of the difficulty of a TT.

scholarly journals Effect of Warm-Up and Sodium Bicarbonate Ingestion on 4-km Cycling Time-Trial Performance

2020 ◽  
pp. 1-7
Author(s):  
William H. Gurton ◽  
Steve H. Faulkner ◽  
Ruth M. James
Keyword(s):  
Sodium Bicarbonate ◽  
Blood Lactate ◽  
Body Mass ◽  
Repeated Measures ◽  
Lactate Concentration ◽  
Time Trial ◽  
Placebo Control ◽  
Warm Up ◽  
Cycling Time Trial ◽  
Cycling Time

Purpose: To examine whether an ecologically valid, intermittent, sprint-based warm-up strategy impacted the ergogenic capacity of individualized sodium bicarbonate (NaHCO3) ingestion on 4-km cycling time-trial (TT) performance. Methods: A total of 8 male cyclists attended 6 laboratory visits for familiarization, determination of time to peak blood bicarbonate, and 4 × 4-km cycling TTs. Experimental beverages were administered doubleblind. Treatments were conducted in a block-randomized, crossover order: intermittent warm-up + NaHCO3 (IWSB), intermittent warm-up + placebo, control warm-up + NaHCO3 (CWSB), and control warm-up + placebo (CWP). The intermittent warm-up comprised exercise corresponding to lactate threshold (5 min at 50%, 2 min at 60%, 2 min at 80%, 1 min at 100%, and 2 min at 50%) and 3 × 10-second maximal sprints. The control warm-up comprised 16.5 minutes cycling at 150 W. Participants ingested 0.3 g·kg body mass−1 NaHCO3 or 0.03 g·kg body mass−1 sodium chloride (placebo) in 5 mL·kg body mass−1 fluid (3:2, water and sugar-free orange squash). Paired t tests were conducted for TT performance. Hematological data (blood bicarbonate and blood lactate) and gastrointestinal discomfort were analyzed using repeated-measures analysis of variance. Results: Performance was faster for CWSB versus IWSB (5.0 [6.1] s; P = .052) and CWP (5.8 [6.0] s; P = .03). Pre-TT bicarbonate concentration was elevated for CWSB versus IWSB (+9.3 mmol·L−1; P < .001) and CWP (+7.1 mmol·L−1; P < .001). Post-TT blood lactate concentration was elevated for CWSB versus CWP (+2.52 mmol·L−1; P = .022). Belching was exacerbated pre-warm-up for IWSB versus intermittent warm-up +placebo (P = .046) and CWP (P = .027). Conclusion: An intermittent, sprint-based warm-up mitigated the ergogenic benefits of NaHCO3 ingestion on 4-km cycling TT performance.

On the Implication of Dietary Nitrate Supplementation for the Hemodynamic and Fatigue Response to Cycling Exercise

2021 ◽  
Author(s):  
Taylor S. Thurston ◽  
Joshua C. Weavil ◽  
Thomas J. Hureau ◽  
Jayson R. Gifford ◽  
Vincent P. Georgescu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Femoral Nerve ◽  
Voluntary Activation ◽  
Peak Power Output ◽  
Cycling Exercise ◽  
Dietary Nitrate ◽  
Task Failure ◽  
Nitrate Supplementation ◽  
The Impact ◽  
Cycling Time

This study investigated the impact of dietary nitrate supplementation on peripheral hemodynamics, the development of neuromuscular fatigue, and time to task failure during cycling exercise. Eleven recreationally active male participants (27±5 years, VO2max: 42±2ml/kg/min) performed two experimental trials following 3 days of either dietary nitrate-rich beetroot juice (4.1mmol NO3-/day; DNS) or placebo (PLA) supplementation in a blinded, counterbalanced order. Exercise consisted of constant-load cycling at 50, 75, and 100 W (4-min each) and, at ~80% of peak power output (218±12W), to task-failure. All participants returned to repeat the shorter of the two trials performed to task-failure, but with the opposite supplementation regime (ISO-time comparison). Mean arterial pressure (MAP), leg blood flow (QL; Doppler ultrasound), leg vascular conductance (LVC), and pulmonary gas exchange were continuously assessed during exercise. Locomotor muscle fatigue was determined by the change in pre- to post-exercise quadriceps twitch-torque (∆Qtw) and voluntary activation (∆VA; electrical femoral nerve stimulation). Following DNS, plasma [nitrate] (~670 vs ~180 nmol) and [nitrite] (~775 vs ~11 nmol) were significantly elevated compared to PLA. Unlike PLA, DNS lowered both QL and MAP by ~8% (P<0.05), but did not alter LVC (P=0.31). VO2 across work rates, as well as cycling time to task-failure (~7min) and locomotor muscle fatigue following the ISO-time comparison were not different between the two conditions (∆Qtw ~42%, ∆VA ~4%). Thus, despite significant hemodynamic changes, DNS did not alter the development of locomotor muscle fatigue and, ultimately, cycling time to task failure.

scholarly journals Prior Exercise Reduces Fast-Start Duration and End-Spurt Magnitude during Cycling Time-Trial

2013 ◽  
Vol 34 (08) ◽  
pp. 736-741 ◽  
Author(s):  
A. Lima-Silva ◽  
C. Correia-Oliveira ◽  
L. Tenorio ◽  
A. Melo ◽  
R. Bertuzzi ◽  
...  
Keyword(s):  
Time Trial ◽  
Cycling Time Trial ◽  
Prior Exercise ◽  
Fast Start ◽  
Cycling Time

scholarly journals Why Train Together When Racing Is Performed Alone? Drafting in Long-Track Speed Skating

2021 ◽  
pp. 1-6
Author(s):  
Floor A.P. van den Brandt ◽  
Inge K. Stoter ◽  
Ruby T.A. Otter ◽  
Marije T. Elferink-Gemser
Keyword(s):  
Heart Rate ◽  
Repeated Measures ◽  
Perceived Exertion ◽  
National Level ◽  
Psychological Impact ◽  
Lactate Concentration ◽  
Time Trial ◽  
Rating Of Perceived Exertion ◽  
Speed Skating ◽  
Perceived Intensity

Purpose: In long-track speed skating, drafting is a commonly used phenomenon in training; however, it is not allowed in time-trial races. In speed skating, limited research is available on the physical and psychological impact of drafting. The aim of this study was to determine the influence of “skating alone,” “leading,” or “drafting” on physical intensity (heart rate and blood lactate) and perceived intensity (perceived exertion) of speed skaters. Methods: Twenty-two national-level long-track speed skaters with a mean age of 19.3 (2.6) years skated 5 laps, with similar external intensity in 3 different conditions: skating alone, leading, or drafting. Repeated-measures analysis of variance showed differences between the 3 conditions, heart rate (F2,36 = 10.546, P < .001), lactate (F2,36 = 12.711, P < .001), and rating of perceived exertion (F2,36 = 5.759, P < .01). Results: Heart rate and lactate concentration were significantly lower (P < .001) when drafting compared with leading (heart rate Δ = 7 [8] beats·min–1, 4.0% [4.7%]; lactate Δ = 2.3 [2.3] mmol/L, 28.2% [29.9%]) or skating alone (heart rate Δ = 8 [7.1] beats·min–1, 4.6% [3.9%]; lactate Δ = 2.8 [2.5] mmol/L, 33.6% [23.6%]). Rating of perceived exertion was significantly lower (P < .01) when drafting (Δ = 0.8 [1.0], 16.5% [20.9%]) or leading (Δ = 0.5 [0.9], 7.7% [20.5%]) versus skating alone. Conclusions: With similar external intensity, physical intensity, as well as perceived intensity, is reduced when drafting in comparison with skating alone. A key finding of this study is the psychological effect: Skating alone was shown to be more demanding than leading, whereas leading and drafting were perceived to be similar in terms of perceived exertion. Knowledge about the reduction of internal intensity for a drafting skater compared with leading or skating alone can be used by coaches and trainers to optimize training conditions.

Influence of All-Out and Fast Start on 5-min Cycling Time Trial Performance

2009 ◽  
Vol 41 (10) ◽  
pp. 1965-1971 ◽  
Author(s):  
BRAD AISBETT ◽  
PETER LEROSSIGNOL ◽  
GLENN Kevin MCCONELL ◽  
CHRIS RICHARD ABBISS ◽  
ROD SNOW
Keyword(s):  
Time Trial ◽  
Time Trial Performance ◽  
Cycling Time Trial ◽  
Fast Start ◽  
Cycling Time ◽  
Trial Performance

Physiological Responses to Exercise on Different Models of the Concept II Rowing Ergometer

2007 ◽  
Vol 2 (4) ◽  
pp. 360-370 ◽  
Author(s):  
Andrew J. Vogler ◽  
Anthony J. Rice ◽  
Robert T. Withers
Keyword(s):  
Blood Lactate ◽  
Physiological Response ◽  
Perceived Exertion ◽  
Physiological Responses ◽  
National Level ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Rating Of Perceived Exertion ◽  
Rowing Ergometer

Purpose:The Concept II model C (IIC) rowing ergometer was replaced by the Concept II model D (IID), but the design modifications of the updated ergometer might alter resistance characteristics and rowing technique, thereby potentially influencing ergometer test results. This study evaluated the physiological response to rowing on the IIC and IID ergometers during a submaximal progressive incremental test and maximal-performance time trial.Methods:Eight national-level rowers completed submaximal and maximal tests on the IIC and IID ergometers separated by 48 to 72 h. Physiological responses and calculated blood lactate thresholds (LT1 and LT2) were compared between ergometer models (IIC vs IID) using standardized drag-factor settings.Results:Power output, oxygen consumption, rowing economy (mL O2 · min−1 · W−1), heart rate, blood lactate concentration, stroke rate, and rating of perceived exertion all displayed similar responses regardless of ergometer model. Calculated physiological values equivalent to LT1 and LT2 were also similar between models, except for blood lactate concentration at LT1, which displayed a small but statistically signifcant difference (P = .02) of 0.2 mmol/L.Conclusions:The physiological response when rowing on IIC and IID ergometers is nearly identical, and testing can therefore be carried out on either ergometer and the results directly compared.

scholarly journals Caffeine increases both total work performed above critical power and peripheral fatigue during a 4-km cycling time trial

2018 ◽  
Vol 124 (6) ◽  
pp. 1491-1501 ◽  
Author(s):  
Leandro Camati Felippe ◽  
Guilherme Assunção Ferreira ◽  
Sara Kely Learsi ◽  
Daniel Boari ◽  
Romulo Bertuzzi ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Critical Power ◽  
Time Trial ◽  
Peripheral Fatigue ◽  
Total Work ◽  
Muscle Recruitment ◽  
Twitch Force ◽  
Cycling Time Trial ◽  
Work Done ◽  
Cycling Time

The link between total work performed above critical power (CP) and peripheral muscle fatigue during self-paced exercise is unknown. We investigated the influence of caffeine on the total work done above CP during a 4-km cycling time trial (TT) and the subsequent consequence on the development of central and peripheral fatigue. Nine cyclists performed three constant-load exercise trials to determine CP and two 4-km TTs ~75 min after oral caffeine (5 mg/kg) or cellulose (placebo) ingestion. Neuromuscular functions were assessed before and 50 min after supplementation and 1 min after TT. Oral supplementation alone had no effect on neuromuscular function ( P > 0.05). Compared with placebo, caffeine increased mean power output (~4%, P = 0.01) and muscle recruitment (as inferred by EMG, ~17%, P = 0.01) and reduced the time to complete the TT (~2%, P = 0.01). Work performed above CP during the caffeine trial (16.7 ± 2.1 kJ) was significantly higher than during the placebo (14.7 ± 2.1 kJ, P = 0.01). End-exercise decline in quadriceps twitch force (pre- to postexercise decrease in twitch force at 1 and 10 Hz) was more pronounced after caffeine compared with placebo (121 ± 13 and 137 ± 14 N vs. 146 ± 13 and 156 ± 11 N; P < 0.05). There was no effect of caffeine on central fatigue. In conclusion, caffeine increases muscle recruitment, which enables greater work performed above CP and higher end-exercise peripheral locomotor muscle fatigue. NEW & NOTEWORTHY The link between total work done above critical power and peripheral fatigue during a self-paced, high-intensity exercise is unclear. This study revealed that caffeine ingestion increases muscle recruitment, which enables greater work done above critical power and a greater degree of end-exercise decline in quadriceps twitch force during a 4-km cycling time trial. These findings suggest that caffeine increases performance at the expense of greater locomotor muscle fatigue.

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