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Purpose: To determine if workload and seasonal periods (preseason vs in season) are associated with the incidence of injuries and illnesses in female professional cyclists. Methods: Session rating of perceived exertion was used to quantify internal workload and was collected from 15 professional female cyclists, from 33 athlete seasons. One week (acute) workload, 4 weeks (chronic) workload, and 3 acute:chronic workload models were analyzed. Two workload models are based on moving averages of the ratios, the acute:chronic workload ratio (ACWR), and the ACWR uncoupled (ACWRuncoup). The difference between both is the chronic load; in ACWR, the acute load is part of the chronic load, and in ACWRuncoup, the acute and chronic load are uncoupled. The third workload model is based on exponentially weighted moving averages of the ratios. In addition, the athlete season is divided into the preseason and in season. Results: Generalized estimating equations analysis was used to assess the associations between the workload ratios and the occurrence of injuries and illnesses. High values of acute workload (P = .048), ACWR (P = .02), ACWRuncoup (P = .02), exponentially weighted moving averages of the ratios (P = .01), and the in season (P = .0001) are significantly associated with the occurrence of injury. No significant associations were found between the workload models, the seasonal periods, and the occurrence of illnesses. Conclusions: These findings suggest the importance of monitoring workload and workload ratios in female professional cyclists to lower the risk of injuries and therefore improve their performances. Furthermore, these results indicate that, in the preseason, additional stressors occur, which could lead to an increased risk of injuries.

Assessment of metabolic energy expenditure from indirect calorimetry is currently limited to sustained (>4 min) cyclic activities, because of steady-state requirements. This is problematic for patient populations who are unable to perform such sustained activities. Therefore, this study explores validity and reliability of a method estimating metabolic energy expenditure based on oxygen consumption (V̇O2) during short walking bouts. Twelve able-bodied adults twice performed six treadmill walking trials (1, 2 and 6 min at 4 and 5 km/h), while V̇O2 was measured. Total V̇O2 was calculated by integrating net V̇O2 over walking and recovery. Concurrent validity with steady-state V̇O2 was assessed with Pearson’s correlations. Test-retest reliability was assessed using intra-class correlation coefficients (ICC) and Bland-Altman analyses. Total V̇O2 was strongly correlated with steady-state V̇O2 (r=0.91–0.99), but consistently higher. Test-retest reliability of total V̇O2 (ICC=0.65–0.92) was lower than or comparable to steady-state V̇O2 (ICC=0.83–0.92), with lower reliability for shorter trials. Total V̇O2 discriminated between gait speeds. Total oxygen uptake provides a useful measure to estimate metabolic load of short activities from oxygen consumption. Although estimates are less reliable than steady-state measurements, they can provide insight in the yet unknown metabolic demands of daily activities for patient populations unable to perform sustained activities.

Background: Gross efficiency (GE) declines during high-intensity exercise. Increasing extracellular buffer capacity might diminish the decline in GE and thereby improve performance. Purpose: To examine if sodium bicarbonate (NaHCO3) supplementation diminishes the decline in GE during a 2000-m cycling time trial. Methods: Sixteen male cyclists and 16 female cyclists completed 4 testing sessions including a maximal incremental test, a familiarization trial, and two 2000-m GE tests. The 2000-m GE tests were performed after ingestion of either NaHCO3 supplements (0.3 g/kg body mass) or placebo supplements (amylum solani, magnesium stearate, and sunflower oil capsules). The GE tests were conducted using a double-blind, randomized, crossover design. Power output, gas exchange, and time to complete the 2000-m time trials were recorded. Capillary blood samples were analyzed for blood bicarbonate, pH, and lactate concentration. Data were analyzed using magnitude-based inference. Results: The decrement in GE found after the 2000-m time trial was possibly smaller in the male and female groups after NaHCO3 than with placebo ingestion, with the effect in both groups combined being unclear. The effect on performance was likely trivial for males (placebo 164.2 [5.0] s, NaHCO3 164.3 [5.0] s; Δ0.1; ±0.6%), unclear for females (placebo 178.6 [4.8] s, NaHCO3 178.0 [4.3] s; Δ−0.3; ±0.5%), and very likely trivial when effects were combined. Blood bicarbonate, pH, and lactate concentration were substantially elevated from rest to pretest after NaHCO3 ingestion. Conclusions: NaHCO3 supplementation results in an unclear effect on the decrease in GE during high-intensity exercise and in a very likely trivial effect on performance.

Purpose: To describe the training intensity and load characteristics of professional cyclists using a 4-year retrospective analysis. Particularly, this study aimed to describe the differences in training characteristics between men and women professional cyclists. Method: For 4 consecutive years, training data were collected from 20 male and 10 female professional cyclists. From those training sessions, heart rate, rating of perceived exertion, and power output (PO) were analyzed. Training intensity distribution as time spent in different heart rate and PO zones was quantified. Training load was calculated using different metrics such as Training Stress Score, training impulse, and session rating of perceived exertion. Standardized effect size is reported as Cohen’s d. Results: Small to large higher values were observed for distance, duration, kilojoules spent, and (relative) mean PO in men’s training (d = 0.44–1.98). Furthermore, men spent more time in low-intensity zones (ie, zones 1 and 2) compared with women. Trivial differences in training load (ie, Training Stress Score and training impulse) were observed between men’s and women’s training (d = 0.07–0.12). However, load values expressed per kilometer were moderately (d = 0.67–0.76) higher in women compared with men’s training. Conclusions: Substantial differences in training characteristics exist between male and female professional cyclists. Particularly, it seems that female professional cyclists compensate their lower training volume, with a higher training intensity, in comparison with male professional cyclists.

Background: During self-paced (SP) time trials (TTs), cyclists show unconscious nonrandom variations in power output of up to 10% above and below average. It is unknown what the effects of variations in power output of this magnitude are on physiological, neuromuscular, and perceptual variables. Purpose: To describe physiological, neuromuscular, and perceptual responses of 10-km TTs with an imposed even-paced (EP) and variable-paced (VP) workload. Methods: Healthy male, trained, task-habituated cyclists (N = 9) completed three 10-km TTs. First, an SP TT was completed, the mean workload from which was used as the mean workload of the EP and VP TTs. The EP was performed with an imposed even workload, while VP was performed with imposed variations in workload of ±10% of the mean. In EP and VP, cardiorespiratory, neuromuscular, and perceptual variables were measured. Results: Mean rating of perceived exertion was significantly lower in VP (6.13 [1.16]) compared with EP (6.75 [1.24]), P = .014. No mean differences were found for cardiorespiratory and almost all neuromuscular variables. However, differences were found at individual kilometers corresponding to power-output differences between pacing strategies. Conclusion: Variations in power output during TTs of ±10%, simulating natural variations in power output that are present during SP TTs, evoke minor changes in cardiorespiratory and neuromuscular responses and mostly affect the perceptual response. Rating of perceived exertion is lower when simulating natural variations in power output, compared with EP cycling. The imposed variations in workload seem to provide a psychological rather than a physiological or neuromuscular advantage.

Although there is evidence supporting the benefit of regular exercise, and recommendations about exercise and physical activity, the process of individually prescribing exercise following exercise testing is more difficult. Guidelines like % heart rate (HR) reserve (HRR) require an anchoring maximal test and do not always provide a homogenous training experience. When prescribing HR on the basis of % HRR, rating of perceived exertion or Talk Test, cardiovascular/perceptual drift during sustained exercise makes prescription of the actual workload difficult. To overcome this issue, we have demonstrated a strategy for “translating” exercise test responses to steady state exercise training on the basis of % HRR or the Talk Test that appeared adequate for individuals ranging from cardiac patients to athletes. However, these methods depended on the nature of the exercise test details. In this viewpoint, we combine these data with workload expressed as Metabolic Equivalent Task (METs). We demonstrate that there is a regular stepdown between the METs during training to achieve the same degree of homeostatic disturbance during testing. The relationship was linear, was highly-correlated (r = 0.89), and averaged 71.8% (Training METs/Test METs). We conclude that it appears possible to generate a generalized approach to correctly translate exercise test responses to exercise training. Sin financiación No data JCR 2020 0.446 SJR (2020) Q2, 18/39 Anatomy No data IDR 2019 UEM

BackgroundIndividuals post-stroke walk slower than their able-bodied peers, which limits participation. This might be attributed to neurological impairments, but could also be caused by a mismatch between aerobic capacity and aerobic load of walking.Research questionWhat is the potential impact of aerobic capacity and aerobic load of walking on walking ability post-stroke?MethodsIn a cross-sectional study, forty individuals post-stroke (more impaired N=21; preferred walking speed (PWS)2/kg/min) and energy cost (mlO2/kg/m) were derived from oxygen uptake . Relative load was defined as energy expenditure divided by peak aerobic capacity and by at ventilatory threshold . Relative load and energy cost at PWS were compared between groups with one-way ANOVA’s. The effect of speed on these parameters was modeled with GEE.ResultsBoth more and less impaired individuals post-stroke showed lower PWS than able-bodied controls (0.44[0.19-0.76] and 1.04[0.81-1.43] vs 1.36[0.89-1.53] m/s) and higher relative load at PWS (50.2±14.4 and 51.7±16.8 vs peak and 101.9±20.5 and 97.0±27.3 vs ). No differences in relative load were found between stroke groups. Energy cost at PWS of more impaired (0.30[.19-1.03] mlO2/kg/m) was higher than less-impaired (0.19[0.10-0.24] mlO2/kg/m) and able-bodied (0.15[0.13-0.18] mlO2/kg/m). For post-stroke individuals, increasing walking speed above PWS decreased energy cost, but resulted in a relative load above endurance threshold.SignificanceIndividuals post-stroke seem to reduce walking speed to prevent unsustainably high relative aerobic loads at the expense of reduced economy. When aiming to improve walking ability in individuals post-stroke, it is important to consider training aerobic capacity.

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.

The aim of this study is to investigate whether the change in (sub)maximal heart rate after intensified training is associated with the change in performance. Thirty subjects were recruited who performed cardiopulmonary exercise tests to exhaustion 2 weeks before (pre), 1 week after (post) and 5 weeks after (follow-up) an 8-day non-competitive amateur cycling event (TFL). The exercise volume during the TFL was 7.7 fold the volume during the preparation period. Heart rate and cardiopulmonary parameters were obtained at standardised absolute submaximal workloads (low, medium and high intensity) and at peak level each test. Subjects were classified as functionally overreached (FOR) or acute fatigued (AF) based on the change in performance. No differences between FOR and AF were observed for heart rate (P =.51). On total group level (AF + FOR), post-TFL heart rate decreased significantly at low (−4.4 beats·min −1 , 95% CI [−8.7, −0.1]) and medium (−5.5 beats·min −1 [−8.5, −2.4]), but not at high intensity. Peak heart rate decreased −3.4 beats·min −1 [−6.1, −0.7]. O 2 pulse was on average 0.49 ml O 2 ·beat −1 [0.09, 0.89] higher at all intensities after intensified training. No changes in ⩒O 2 (P =.44) or the ventilatory threshold (P =.21) were observed. Pearson’s correlation coefficients revealed negative associations between heart rate and O 2 pulse at low (r = −.56, P 2 or any other submaximal parameter. (Sub)maximal heart rate decreased after the TFL. However, this decrease is unrelated to the change in performance. Therefore, heart rate seems inadequate to prescribe and monitor intensified training.

Purpose:To examine the influence of induced changes in the morphology of the leg by adding mass on the optimal step length (OSL) in experienced runners to get more insight into parameters that influence preferred step length (PSL) and OSL.Methods:Thirteen experienced male runners (mean age 26.9 ± 6.1 y, height 183.7 ± 7.1 cm, mass 71.8 ± 5.9 kg) ran on a treadmill in 3 different conditions: unloaded (UL), loaded with 2 kg mass at the ankles (MA), and loaded with 2 kg mass at the hips (MH) at 7 different step lengths (SLs). SL deviations were expressed as deviations in relative leg length (%LL) from the individual PSL: 0%LL, ±5%LL, ±10%LL, and ±15%LL. Trials lasted 8 min, and 8 min of rest was given between trials. Oxygen uptake (V̇O2) was expressed as a fraction of V̇O2 at PSL + 0%LL in the unloaded condition (%V̇O2). The %SL with the lowest value of %V̇O2 was considered the OSL for this group of participants.Results:OSL at the UL condition was 6% shorter than PSL. The MA condition resulted in a 7%LL larger OSL than at UL and MH (P < .05).Conclusions:The mass distribution of the leg is a determinant of the OSL. As a consequence of the added mass to the ankles, OSL was 7%LL longer. Morphological characteristics of the leg might therefore play an important role in determining the runner’s individual optimal SL.

The Rating of Perceived Exertion (RPE) is an important measure of exercise intensity, which is useful both as a primary and adjunctive method of exercise prescription. However, there are multiple variants of the Borg RPE scale, primarily the Borg 6-20 RPE scale (BORG-RPE) and the Borg Category-Ratio-10 scale (BORG-CR10). There are inadequate data available to address the comparability and interchangeability of these two widely used scales. Well-trained non-athletes performed two increment cycle tests, with each scale used in a random sequence. Subjects also performed interval sessions at three intensities (50, 75 and 85% of peak power output) with each scale used in a random sequence. There were very large correlations during the incremental exercise between the conventional physiological measures (% heart rate reserve – r=0.89 & r=.87); and %VO2reserve (r=.88 & r=.90) and RPE measured by either the BORG-RPE or the BORG-CR10, respectively. This pattern was also evident during the interval exercise (% heart rate reserve – r=.85 & r=.84; and blood lactate concentration – r=.74 & r=.78) and RPE measured by either the BORG-RPE or the BORG-CR10, respectively. The relationship between RPE measured by the BORG-RPE and the BORG-CR10 was large and best described by a non-linear relationship for both the incremental (R2=.89) and the interval (R2=.89) exercise. The incremental and interval curves were virtually overlapping. We concluded that the two most popular versions of the RPE scale, BORG-RPE and BORG-CR10, were both highly related to the conventional physiological measures and very strongly related to each other, with an easily described conversion.

Endurance exercise is associated with a transient increase in neutrophil counts in the peripheral blood. Here we investigate the impact of intensified endurance exercise on the neutrophil compartment. We hypothesized that intensified endurance exercise leads to mobilization of neutrophil subsets, which are normally absent in the blood. Furthermore, we followed the potential build-up of neutrophil activation and the impact on overnight recovery of the neutrophil compartment during a seven-day cycling tour. The neutrophil compartment was studied in 28 healthy amateur cyclists participating in an eight-day strenuous cycling tour. Blood samples were taken at baseline, after 4 days and after 7 days of cycling. The neutrophil compartment was analyzed in terms of numbers and its phenotype by deep phenotyping of flow cytometry data with the multi-dimensional analysis method FLOOD. Repeated endurance exercise led to a gradual increase in total neutrophil counts over the days leading to a 1.26 fold-increase (95%CI 1.01-1.51 p = 0.0431) in the morning of day 8. Flow cytometric measurements revealed the appearance of 2 additional neutrophil subsets: CD16brightCD62Ldim and CD16dimCD62Lbright. A complex change in neutrophil phenotypes was present characterized by decreased expression of both CD11b and CD62L and marked increased expression of LAIR-1, VLA-4 and CBRM1/5. The changes in expression were found on all neutrophils present in the blood. Strikingly, in strong contrast to our findings during acute inflammation evoked by LPS challenge, these neutrophils did not upregulate classical degranulation markers. In fact, our FLOOD analysis revealed that the exercise induced neutrophil phenotype did not overlap with the neutrophil subsets arising upon acute inflammation. In conclusion, during multiple days of endurance exercise the neutrophil compartment does not regain homeostasis overnight. Thereby our study supports the concept of a build-up of inflammatory cues during repeated endurance exercise training, causing a prolonged change of the systemic neutrophil compartment.

Optimizing physical performance is a major goal in current physiology. However, basic understanding of combining high sprint and endurance performance is currently lacking. This study identifies critical determinants of combined sprint and endurance performance using multiple regression analyses of physiologic determinants at different biologic levels. Cyclists, including 6 international sprint, 8 team pursuit, and 14 road cyclists, completed a Wingate test and 15-km time trial to obtain sprint and endurance performance results, respectively. Performance was normalized to lean body mass2/3to eliminate the influence of body size. Performance determinants were obtained from whole-body oxygen consumption, blood sampling, knee-extensor maximal force, muscle oxygenation, whole-muscle morphology, and muscle fiber histochemistry of musculus vastus lateralis. Normalized sprint performance was explained by percentage of fast-type fibers and muscle volume ( R2= 0.65; P < 0.001) and normalized endurance performance, by performance oxygen consumption ( V̇o2), mean corpuscular hemoglobin concentration, and muscle oxygenation ( R2= 0.92; P < 0.001). Combined sprint and endurance performance was explained by gross efficiency, performance V̇o2, and likely by muscle volume and fascicle length ( P = 0.056; P = 0.059). High performance V̇o2related to a high oxidative capacity, high capillarization × myoglobin, and small physiologic cross-sectional area ( R2= 0.67; P < 0.001). Results suggest that fascicle length and capillarization are important targets for training to optimize sprint and endurance performance simultaneously.-Van der Zwaard, S., van der Laarse, W. J., Weide, G., Bloemers, F. W., Hofmijster, M. J., Levels, K., Noordhof, D. A., de Koning, J. J., de Ruiter, C. J., Jaspers, R. T. Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body.

PURPOSE: Exercise-based rehabilitation is a standard therapy for patients with heart disease. Despite examples of patients who have extended normal rehabilitation exercise into competitive participation, there are no clear-cut guidelines for patients whether they should participate in competitive-level exercise. This study investigated the occurrence of complications, physiologic responses, and exercise patterns during simulated competitive exercise in active, older nonathletes (most with a history of cardiovascular disease) and compared these with responses during maximal incremental exercise. METHODS: Fourteen trained older males, 7 with stable cardiovascular disease, performed an incremental exercise test and time trial of 55 kJ (equivalent to running ~ 1 mile) on a semirecumbent stepping ergometer. Variables of gas exchange, hemodynamics, perception, and power output were measured in both tests. RESULTS: Subjects attained a remarkably high physiologic and psychologic strain (respiratory exchange ratio 1.0; average peak rating of perceived exertion 8) in both tests, with no evidence of symptomatic, hemodynamic, or electrocardiographic abnormalities. Peak physiologic responses were not significantly different between simulated competition and incremental exercise. The fixed-work time trial was finished in 8.97 ± 1.85 minutes, mean power output of 100 ± 26 W. Results showed a distinct pacing pattern in the relative power output, consisting of a conservative start, an even-paced middle portion, and an end spurt. CONCLUSIONS: Results suggest that in trained individuals with normal incremental exercise test results, competitive-level efforts may be undertaken with no apparent side effects. This may provide a strategy whereby physicians can advise patients concerning their decision to perform in competitive events.

Rowers need to combine high sprint and endurance capacities. Muscle morphology largely explains muscle power generating capacity, however, little is known on how muscle morphology relates to rowing performance measures. The aim was to determine how muscle morphology of the vastus lateralis relates to rowing ergometer performance, sprint and endurance capacity of Olympic rowers. Eighteen rowers (12♂, 6♀, who competed at 2016 Olympics) performed an incremental rowing test to obtain maximal oxygen consumption, reflecting endurance capacity. Sprint capacity was assessed by Wingate cycling peak power. M. vastus lateralis morphology (volume, physiological cross-sectional area, fascicle length and pennation angle) was derived from 3-dimensional ultrasound imaging. Thirteen rowers (7♂, 6♀) completed a 2000-m rowing ergometer time trial. Muscle volume largely explained variance in 2000-m rowing performance (R2 = 0.85), maximal oxygen consumption (R2 = 0.65), and Wingate peak power (R2 = 0.82). When normalized for differences in body size, maximal oxygen consumption and Wingate peak power were negatively related in males (r = −0.94). Fascicle length, not physiological cross-sectional area, attributed to normalized peak power. In conclusion, vastus lateralis volume largely explains variance in rowing ergometer performance, sprint and endurance capacity. For a high normalized sprint capacity, athletes may benefit from long fascicles rather than a large physiological cross-sectional area.

Background: Research has shown that gross efficiency (GE) declines during high-intensity exercise, but the time course of recovery of GE after high-intensity exercise has not yet been investigated. Purpose: To determine the time course of the recovery of GE after time trials (TTs) of different lengths. Methods: Nineteen trained male cyclists participated in this study. Before and after TTs of 2000 and 20,000 m, subjects performed submaximal exercise at 55% of the power output attained at maximal oxygen uptake (PVO2max). The postmeasurement continued until 30 min after the end of the TT, during which GE was determined over 3-min intervals. The magnitude-based-inferences approach was used for statistical analysis. Results: GE decreased substantially during the 2000-m and 20,000-m TTs (−11.8% [3.6%] and −6.2% [4.0%], respectively). A most likely and very likely recovery of GE was found during the first half of the submaximal exercise bout performed after the 2000-m, with only a possible increase in GE during the first part of the submaximal exercise bout performed after the 20,000-m. After both distances, GE did not fully recover to the initial pre-TT values, as the difference between the pre-TT value and average GE value of minutes 26–29 was still most likely negative for both the 2000- and 20,000-m (−6.1% [2.8%] and −7.0% [4.5%], respectively). Conclusions: It is impossible to fully recover GE after TTs of 2000- or 20,000-m during 30 min of submaximal cycling exercise performed at an intensity of 55% PVO2max.

Purpose: Reaction time has been proposed as a training monitoring tool, but to date, results are equivocal. Therefore, it was investigated whether reaction time can be used as a monitoring tool to establish overreaching. Methods: The study included 30 subjects (11 females and 19 males, age: 40.8 [10.8] years, VO2max: 51.8 [6.3] mL/kg/min) who participated in an 8-day cycling event. The external exercise load increased approximately 900% compared with the preparation period. Performance was measured before and after the event using a maximal incremental cycling test. Subjects with decreased performance after the event were classified as functionally overreached (FOR) and others as acutely fatigued (AF). A choice reaction time test was performed 2 weeks before (pre), 1 week after (post), and 5 weeks after (follow-up), as well as at the start and end of the event. Results: A total of 14 subjects were classified as AF and 14 as FOR (2 subjects were excluded). During the event, reaction time at the end was 68 ms (95% confidence interval, 46-89) faster than at the start. Reaction time post event was 41 ms (95% confidence interval, 12-71) faster than pre event and follow-up was 55 ms faster (95% confidence interval, 26-83). The time by class interaction was not significant during (P = .26) and after (P = .43) the event. Correlations between physical performance and reaction time were not significant (all Ps < .30). Conclusions: No differences in choice reaction time between AF and FOR subjects were observed. It is suggested that choice reaction time is not valid for early detection of overreaching in the field.

Previous studies have found decreases in arterial oxygen saturation to be temporally linked to reductions in power output (PO) during time-trial (TT) exercise. The purpose of this study was to determine whether preexercise desaturation (estimated from pulse oximetry [SpO2]), via normobaric hypoxia, would change the pattern of PO during a TT.Purpose:The authors tested the hypothesis that the starting PO of a TT would be reduced in the EARLY trial secondary to a reduced SpO2 but would not be reduced in LATE until ~30 s after the start of the TT.Methods:Eight trained cyclists/triathletes (4 male, 4 female) performed 3 randomly ordered 3-km TTs while breathing either room air (CONTROL) or hypoxic air administered 3 min before the start of the TT (EARLY) or at the beginning of the TT (LATE).Results:There was no effect of hypoxia on PO during the first 0.3 km of either the EARLY or the LATE trial compared with CONTROL, although there was a significant decrease in pre-TT SpO2 in EARLY vs CONTROL and LATE. The time for PO to decrease was ~40 s after the start of the TT in both EARLY and LATE.Conclusions:The results support the strong effect of the preexercise template on the pattern of PO during simulated competition and suggest that reductions in SpO2 are not direct signals to decrease PO.

HETTINGA, F. J., J. J. DE KONING, F. T. BROERSEN, P. VAN GEFFEN, and C. FOSTER. Pacing Strategy and the Occurrence of Fatigue in 4000-m Cycling Time Trials. Med. Sci. Sports Exerc., Vol. 38, No. 8, pp. 1484–1491, 2006. Purpose: The present study was designed to examine the role of central and peripheral fatigue on 4000-m cycling time trial performance by comparing changes in power output and integrated electromyography (iEMG) in differently paced maximal efforts. Methods: Eight well-trained men performed three randomly ordered time trials with different pacing strategies, in which the first 2000 m were manipulated to evoke an increasing, even, and decreasing power output profile (SUB, EVEN, and SUPRA, respectively). Subjects were instructed to finish the last 2000 m of all trials in the shortest time possible. iEMG of the rectus femoris (RF), vastus lateralis (VL), and biceps femoris (BF) muscle, mechanical power output, and gas exchange variables were measured. Anaerobic and aerobic contributions to mechanical power output were calculated from gas exchange data. Results: The increase in mechanical power output during the SUB time trials was always associated with an increase in iEMG in all muscles. A decrease in mechanical power output near the end of the time trials was also marked by an increase in iEMG for all muscles, except for the RF. Comparing the last 2000-m interval with the first, aerobic power output increased for all strategies. Anaerobic power output increased in SUB and decreased in EVEN and SUPRA. Conclusion: The relationship between iEMG and mechanical power output pattern was consistent with peripheral fatigue rather than central downregulation of mechanical power output. Specifically, anaerobic energy resources seem to be important in regulating

Lower extremity (LE) exercise training has been shown to contribute to improvements in Maximum Walking Distance (MWD), Claudication Distance (CD), peak oxygen uptake (VO2peak) and Quality of Life (QoL) in patients with intermittent claudication (IC). However, little is known regarding the efficacy of upper extremity (UE) exercise training in comparison to the widely used LE training. The objective of this systematic literature review is to identify and synthesize the available literature on the effects of UE versus LE exercises using the International Classification of Functioning (ICF) conceptual framework. A total of 6 randomized controlled trials comparing UE to LE exercises were included in this study. Two of the articles were considered to be of high quality using the PEDro grading list. Both UE and LE training groups demonstrated significant improvements in MWD, CD, VO2peak and QoL in comparison to the control group but LE was not better than UE training. This supports the use of UE training as an alternative to LE, which could provide symptomatic relief to patients with IC without the discomfort caused during the LE training. 3.942 JCR (2015) Q1, 12/63 Peripheral vascular disease UEM

During exercise the renin-angiotensin system is stimulated. We hypothesized that the increase in serum angiotensin II (AngII) levels after exercise is dependent on exercise intensity and duration and secondly that people with the ACE-II genotype will show a higher increase in AngII serum levels. We also assumed that perfusion of upper limbs is transiently reduced with maximal cycling exercise and that subjects with the ACE-II compared to the ACE-ID/DD genotype will have a higher capillary perfusion due to lower AngII levels. Ten healthy subjects completed a maximal exercise test, a 12-min exercise test at ventilatory threshold and a 3-min test at the respiratory compensation point. AngII serum levels and capillary recruitment of the skin in the third finger were measured before and after exercise and breath-by-breath gas exchange during exercise was assessed. Baseline levels of AngII levels were lower prior to the 3-min test which took place on average 5. days after the last exercise. A two-fold increase compared to baseline levels was found for AngII only immediately after the 3-min test and not after the maximal exercise test and 12-min of exercise. Subjects without the I allele showed a decrease in AngII values after the maximal test in contrast to subjects with the ACE-II/ID genotype. Subjects with the ACE-II genotype had a 1.8 times significant higher capillary perfusion in the finger after exercise. A trend was observed for a 34.3% decreased capillary recruitment in the ACE-ID/DD genotype after exercise. We conclude that the rise in AngII after exercise is intensity dependent and that variability in serum AngII and capillary perfusion is related to the ACE I/D polymorphism.

Purpose:To reach top performance in cycling, optimizing distribution of energy resources is crucial. The purpose of this study was to investigate power output during 250-m, 500-m, and 1000-m cycling time trials and the characteristics of the adopted pacing strategy.Methods:Nine trained cyclists completed an incremental test and 3 time trials that they were instructed to finish as quickly as possible. Preceding the trials, peak power during short sprints (PPsprint) and gross efficiency (GE) were measured. During the trials, power output and oxygen consumption were measured to calculate the contribution of the aerobic and anaerobic energy sources. After the trial GE was measured again.Results:Peak power during all trials (PPTT) was lower than PPsprint. In the 250-m trial the PPTT was higher in the 1000-m trial (P = .008). The subjects performed a significantly longer time at high intensity in the 250-m than in the 1000-m (P = .029). GE declined significantly during all trials (P < .01). Total anaerobically attributable work was less in the 250-m than in the 500-m (P = .015) and 1000-m (P < .01) trials.Conclusion:The overall pacing pattern in the 250-m trial appears to follow an all-out strategy, although peak power is still lower than the potential maximal power output. This suggests that a true all-out pattern of power output may not be used in fixed-distance events. The 500-m and 1000-m had a more conservative pacing pattern and anaerobic power output reached a constant magnitude.

The purpose of this study was to investigate the effect of pacing strategies on performance times in the 1000 m time trial event and the 4000 m pursuit event in track cycling. For this purpose, we simulated these events with a model based on the flow of energy in cycling. Different strategies in distributing the available anaerobic energy were evaluated and we compared model predictions of split times and final times with values achieved by cyclists during championships. The best result at the 1000 m time trial was obtained when the cyclist had the highest anaerobic peak power output and used an 'all-out' strategy. The fastest time on the 4000 m pursuit was achieved with an 'all-out' start at a high level of initial power output, followed by a constant anaerobic power output after 12 seconds, resulting in an evenly paced race. The results show that even small variations in pacing strategy may have substantial effects on performance. There seems to be an opportunity to gain a competitive advantage when individual athletes experiment with small variations in pacing strategy to find the precise individual strategy that works best under specific conditions.

PURPOSE: The objective of this study is to compare the maximal aerobic and anaerobic exercise responses of children with cerebral palsy (CP) by level of motor impairment and in comparison with those of typically developing children (TD). METHODS: Seventy children with CP, with varying levels of motor impairment (Gross Motor Function Classification System (GMFCS) I-III), and 31 TD performed an incremental continuous maximal aerobic exercise test and a 20-s anaerobic Wingate test on a cycle ergometer. Peak oxygen uptake (VO2peak), anaerobic threshold (AT), peak ventilation (VEpeak), peak oxygen pulse (peak O2 pulse), peak ventilatory equivalent of oxygen (peak VE/VO2) and carbon dioxide (peak VE/VCO2), peak aerobic power output (POpeak), and mean anaerobic power (P20mean) were measured. Isometric leg muscle strength was determined as a secondary outcome. RESULTS: Analysis revealed a lower VO2peak for CP (I: 35.5 ± 1.2 (SE); II: 33.9 ± 1.6; III: 29.3 ± 2.5 mL·kg·min) compared with TD (41.0 ± 1.3, P < 0.001) and a similar effect for AT (I: 19.4 ± 0.9; II: 19.2 ± 1.2; III: 15.5 ± 1.9; TD: 24.1 ± 1.0 mL·kg·min, P < 0.001). VEpeak and peak O2 pulse were also lower, whereas peak VE/VCO2 was higher in CP compared with TD (P < 0.05) and peak VE/VO2 similar between groups. All these variables showed no differences for different motor impairment levels. POpeak was lower for CP (I: 2.4 ± 0.1; II: 1.8 ± 0.1; III: 1.4 ± 0.2 W·kg) versus TD (3.0 ± 0.1, P < 0.001), together with a lower P20mean in CP (I: 4.6 ± 0.2; II: 3.3 ± 0.2; III: 2.5 ± 0.4 W·kg) versus TD (6.4 ± 0.2, P < 0.001), and both decreased significantly with increasing motor impairment. CONCLUSION: Children with CP have decreased aerobic and anaerobic exercise responses, but decreases in respiratory and aerobic exercise responses were not as severe as predicted by motor impairment. Future research should reveal the role of inactivity on the exercise responses of children with CP and possibilities for improvement through training interventions. Copyright © 2013 by the American College of Sports Medicine.

Aerobic exercise performance is seriously compromised in the heat. Possibly, a high skin temperature causes a rating of perceived exertion (RPE)-mediated decrease in exercise intensity. The purpose of this study was to determine the effect of skin temperature on power output during a 7.5-km cycling time trial. Thirteen well-trained male subjects performed a 7.5-km cycling time trial at 15°C and 50% relative humidity (CONTROL), with radiative heat stress during the time trial, and with (PRECOOL) or without (HEAT) precooling. Heat stress was applied by infrared heaters positioned in front of the cycle ergometer between 1.5 and 6.0 km. Skin, rectal, and pill temperature, power output, heart rate, and RPE were measured during the trial. Despite the lower mean skin temperature at the start of the time trial for PRECOOL compared to HEAT (-2.1 ± 0.7°C; P < 0.01) and CONTROL (-1.8 ± 0.6°C; P < 0.05), and a greater increase in mean skin temperature during the heat stress period for PRECOOL (4.5 ± 1.0°C) and HEAT (3.9 ± 0.8°C) than for CONTROL (-0.3 ± 0.6°C; P < 0.01), no differences in power output were found between HEAT (273 ± 45 W) and CONTROL (284 ± 43 W; P = 0.11) and between HEAT and PRECOOL (266 ± 50 W; P = 0.47). Power output during the time trial was greater for CONTROL than for PRECOOL (P < 0.05). Additionally, no differences were observed in core temperature measures, HR, and RPE. Skin temperature does not affect the selection and modulation of exercise intensity in a 7.5-km cycling time trial. © 2012 The Author(s).

An analysis of the start of the 500 m speed skating races during the 1988 Olympic Winter Games showed a remarkably high correlation between the acceleration of the skater in the first second of the sprint and the final time (r = -0.75). In this study a power equation is used to explain this high coefficient of correlation. The performance in speed skating is determined by the capability of external power production by the speed skater. This power is necessary to overcome the air and ice friction and to increase the kinetic energy of the skater. Numerical values of the power dissipated to air and ice friction, both dependent on speed, are obtained from ice friction and wind tunnel experiments. Using aerobic and anaerobic power production as measured during supra maximal bicycle tests of international-level speed skaters, a model of the kinetics of power production is obtained. Simulation of power production and power dissipation yields values of speed and acceleration and, finally, the performance time of the sprint during speed skating. The mean split time at 100 m and the final time at 500 m in these races, derived from simulation, were 10.57 s (+/- 0.31) and 37.82 s (+/- 0.96), respectively. The coefficient of correlation between the simulated 500 m times and the actual 500 m times was 0.90. From the results of this study it can be concluded that the distribution of the available anaerobic energy is an important factor in the short lasting events. For the same amount of anaerobic energy the better sprinters appear to be able to liberate considerably more energy at the onset of the race than skaters of lower performance level.

Limited research has been done on the .VO2 response to time trial exercise in the supramaximal domain or during free range exercise typical of competition. The present study was designed to measure and to model the .VO2 response during supramaximal time trial exercise.Well-trained cyclists (n = 9) performed a 1-min incremental exercise test to obtain maximal power output (P (.VO2max)) and four cycle ergometer time trials of different distances (750, 1500, 2500, and 4000 m). Athletes were instructed to finish in as little time as possible. .VO2 was measured breath-by-breath and modeled monoexponentially over the first 54 s (750 m) or 114 s (1500, 2500, and 4000 m) of the time trials.Mean P (.VO2max) in the incremental test was 383 +/- 28 W. Mean .VO(2max) was 4.5 +/- 0.2 L.min(-1). All time trials were characterized by an initial burst in power output during the first 15 s (175 +/- 23%, 149 +/- 14%, 145 +/- 14%, 139 +/- 10% P (.VO2max) being largest for 750 m. Simultaneously, the mean response time was significantly smaller in 750 m compared with all other trials (18.8 +/- 2.2, 20.9 +/- 1.9, 20.8 +/- 1.5, and 21.2 +/- 2.2 s).Near maximal values of .VO2 can be reached within 2 min of strenuous exercise. The larger initial burst in power output in 750 m was accompanied by a faster .VO2 response and seems to be of importance to trigger the aerobic system maximally.

Five speed skaters of elite performance level and six speed skaters of trained level were subjected to an inverse dynamical analysis during speed skating. Push-off forces were registered by means of special skates. Myoelectric activity (EMG) of ten leg muscles and cinematographic data were recorded. Linked segment modelling yielded net joint moments and joint powers. The speed skating technique is characterized by a typical horizontal position of the trunk and a suppression of a plantar flexion during the push-off. This technique, necessary to reduce external friction, constrains the transfer of rotation in joints to translation of the mass center of the body. In spite of constrained push-off, the EMG levels of the leg muscles show a proximo-distal temporal order which to a certain extent is comparable to that previously found in an unconstrained vertical jump. This proximo-distal sequence is also reflected by the time courses of the net moment and net power output in hip, knee and ankle joints. The temporal sequence in activation levels of activated muscles is not different between elite and trained speed skaters. The difference in performance level between these groups obviously has an origin in the ability of the elite speed skaters to realise larger net joint moments. Differences in net joint moments and in kinematics result in a higher power output and a lower air frictional force for the elite than for the trained speed skaters.

BACKGROUND: Previous studies suggest that the rating of perceived exertion (RPE) increases during steady-state, open-loop exercise in proportion to the relative time to fatigue. This suggests that RPE is scalar and integrates physiological status and homeostatic disturbances. PURPOSE: This study assessed the relationship between the rate of change in RPE, and relative distance in time trials at distances of 2.5, 5, and 10 km. It also assessed the rate of change in RPE during 5-km time trials while breathing hypoxic air. METHODS: The subjects were well-conditioned cyclists. In part 1, each subject completed habituation time trials, and then randomly ordered time trials at each distance. The category ratio RPE was measured in 10% increments throughout each trial. In part 2, each subject completed three 5-km time trials while breathing different inspired gas mixtures (FiO2 = 0.2093 throughout the trial, FiO2 = 0.15 between 2 and 4 km, and FiO2 = 0.15 between 2.5 and 4 km). RPE was measured at 10% increments. RESULTS: In part 1, when RPE was plotted against relative distance, there was no significant difference in the growth of RPE at proportional distances. In part 2, the decrease in power output during the hypoxic segments was sufficient that the growth of RPE was the same at each proportional distance. In both parts of the study, an RPE of 5 (hard) was achieved after 20% of the time trial distance, and an RPE of 8 was achieved after 80% distance. CONCLUSIONS: This study supports the hypothesis that RPE increases similarly in relation to relative distance, regardless of the distance performed, and it suggests that the perception of effort has scalar properties. ©2008The American College of Sports Medicine.

Portable equipment for active measurements of push-off force and ice friction was developed. The equipment consists of a pair of skates with three measuring elements between the shoe and the skate blade to register force in both fore/aft and normal direction. A portable computer samples the friction force and normal force signals during one or more strokes, calculates the mean coefficient of ice friction, and stores the sampled data in memory. The push-off force and ice friction force were measured. The peak push-off forces reach values of up to 140% of body weight. The magnitude of the coefficient of ice friction varies, depending on the weather conditions and preparatory method, generally between 0.003 and 0.007 when skating the straightaway. During the skating of the curves the coefficient of ice friction is 35% higher, most likely due to the different skating technique in the curves.

PURPOSE: Athletes occasionally follow pacing patterns that seem unreasonably aggressive compared with those of prerace performances, potentially because of the motivation provided by competition. This study evaluated the effect of extrinsic motivation on cyclists' time trial performance. METHODS: Well-trained recreational cyclists (N = 7) completed four 1500-m laboratory time trials including a practice trial, two self-paced trials, and a trial where a monetary reward was offered. Time, total power output, power output attributable to aerobic and anaerobic metabolic sources, V̇O2, and HR were measured. RESULTS: The time required for the second, third, and last (extrinsically motivated) time trials was 133.1 ± 2.1, 134.1 ± 3.4, and 133.6 ± 3.0 s, respectively, and was not different (P > 0.05). There were no differences for total (396 ± 19, 397 ± 23, and 401 ± 17 W), aerobic (253 ± 12, 254 ± 10, and 246 ± 13 W), and anaerobic (143 ± 14, 143 ± 21, and 155 ± 11 W) power output. The highest V̇O2 was not different over consecutive time trials (3.76 ± 0.19, 3.73 ± 0.16, and 3.71 ± 0.22 L·min). When ranked by performance, without reference to the extrinsic motivation (131.9 ± 2.4, 133.4 ± 2.4, and 135.4 ± 2.5 s), there was a significant difference for the first 100 m and from 100 to 300 m in power output, with a larger total power (560 ± 102, 491 ± 82, and 493 ± 93; and 571 ± 94, 513 ± 41, and 484 ± 88 W) and power attributable to anaerobic sources (446 ± 100, 384 ± 80, and 324 ± 43; and 381 ± 87, 383 ± 90, and 289 ± 91 W) for the fastest trial. CONCLUSION: Extrinsic motivation did not change the time trial performance, suggesting that 1500-m performance is extremely stable and not readily changeable with simple external motivation. The results suggest that spontaneous improvement in performance for time trials of this duration is attributable to greater early power output, which is primarily attributable to anaerobic metabolic sources. ©2007The American College of Sports Medicine.

Purpose: This study was designed to determine the effect of warm-up on 3-km cycling time trial (TT) performance, and the influence of accelerated V̇O2 kinetics on such effect. Methods: Eight well-trained road cyclists, habituated to 3-km time trials, performed randomly ordered 3-km TT after a) no warm-up (NWU), b) easy warm-up (EWU) (15 min comprised of 5-min segments at 70, 80, and 90% of ventilatory threshold (VT) followed by 2 min of rest), or c) hard warm-up (HWU) (15 min comprised of 5-min segments at 70, 80, and 90% VT, plus 3 min at the respiratory compensation threshold (RCT) followed by 6 min of rest). V̇O2 and power output (SRM), aerobic and anaerobic energy contributions, and V̇O2 kinetics (mean response time to 63% of the V̇O2 observed at 2 km) were determined throughout each TT. Results: Three-kilometer TT performance was (P < 0.05) improved for both EWU (266.8 ± 12.0 s) (−2.8%) and HWU (267.3 ± 10.4 s) (−2.6%) versus NWU (274.4 ± 12.1 s). The gain in performance was predominantly during the first 1000 m in both EWU (48% of gain) and HWU (53% of gain). This reflected a higher power output during the first 1000 m in both EWU (384 W) and HWU warm-up (386 W) versus NWU (344 W) trials. The mean response time was faster in both EWU (45 ± 10 s) and HWU (41 ± 12 s) versus NWU (52 ± 13 s) trials. There were no differences in anaerobic power output during the trials, but aerobic power output during the first 1000 m was larger during both EWU (203 W) and HWU (208 W) versus NWU (163 W) trials. Conclusions: During endurance events of intermediate duration (4–5 min), performance is enhanced by warm-up irrespective of warm-up intensity. The improved performance is related to an acceleration of V̇O2 kinetics. Sin financiación 2.831 JCR (2005) Q1, 4/70 Sport sciences UEM

HOUDIJK, H., M. F. BOBBERT, J. J. DE KONING, and G. DE GROOT. The Effects of Klapskate Hinge Position on Push-off Performance: A Simulation Study. Med. Sci. Sports Exerc., Vol. 35, No. 12, pp. 2077–2084, 2003. Purpose: The introduction of the klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating. Method: For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, twodimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body’s center of mass at take off (W eff). Results: Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25% at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (W mus) and the efficacy ratio (Weff/Wmus) of the entire leg system. Conclusion: Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice. Key Words: SPEED SKATING, SPORTS EQUIPMENT, LOCOMOTION, MUSCULO-SKELETAL MODEL, BIOMECHANICS

Mechanical characteristics of the sprint start in speed skating were measured during the 1988 Winter Olympic Games. From three-dimensional film analysis of the first 4 seconds of the male and female 500-m races, biomechanical variables were determined. The first strokes during the start appeared to be performed by a running-like technique. At a forward velocity of approximately 4 m/sec, the skaters are forced to change this technique to the typical gliding technique as used during speed skating at steady speed. In explaining the time differences on the first 100 meters of the 500-m speed skating race, the effectiveness of the push-off appears to be more important than the observed high power output levels.