Human muscle power generating capability during cycling at different pedalling rates

The effect of different pedalling rates (40, 60, 80, 100 and 120 rev min-1) on power generating capability, oxygen uptake (O2) and blood lactate concentration [La]b during incremental tests was studied in seven subjects. No significant differences in O2,max were found (mean +/- S.D., 5.31 +/- 0.13 l min-1). The final external power output delivered to the ergometer during incremental tests (PI,max) was not significantly different when cycling at 60, 80 or 100 rev min-1 (366 +/- 5 W). A significant decrease in PI,max of 60 W was observed at 40 and 120 rev min-1 compared with 60 and 100 rev min-1, respectively (P < 0.01). At 120 rev min-1 there was also a pronounced upward shift of the O2-power output (O2-P) relationship. At 50 W O2 between 80 and 100 rev min-1 amounted to +0.43 l min-1 but to +0.87 l min-1 between 100 and 120 rev min-1. The power output corresponding to 2 and 4 mmol l-1 blood lactate concentration (P[La]2 and P[La]4 ) was also significantly lower (> 50 W) at 120 rev min-1 (P < 0.01) while pedalling at 40, 60, 80 and 100 rev min-1 showed no significant difference. The maximal peak power output (PM, max) during 10 s sprints increased with pedalling rate up to 100 rev min-1. Our study indicates that with increasing pedalling rate the reserves in power generating capability increase, as illustrated by the PI,max/PM,max ratio (54.8, 44.8, 38.1, 34.6, 29.2%), the P[La]4/PM,max ratio (50.4, 38.9, 31.0, 27.7, 22.9%) and the P[La]2/PM,max ratio (42.8, 33.5, 25.6, 23.1, 15.6%) increases. Taking into consideration the O2,max, the PI,max and the reserve in power generating capability we concluded that choosing a high pedalling rate when performing high intensity cycling exercise may be beneficial since it provides greater reserve in power generating capability and this may be advantageous to the muscle in terms of resisting fatigue. However, beyond 100 rev min-1 there is a decrease in external power that can be delivered for an given O2 with an associated earlier onset of metabolic acidosis and clearly this will be disadvantageous for sustained high intensity exercise.     

Neuromuscular fatigue during prolonged pedalling exercise at different pedalling rates

The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) V·min^–1] was significantly smaller (P < 0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.     

Optimal pedalling velocity characteristics during maximal and submaximal cycling in humans

The aim of this study was to compare optimal pedalling velocities during maximal (OVM) and submaximal (OVSM) cycling in human, subjects with different training backgrounds. A group of 22 subjects [6 explosive (EX), 6 endurance (EN) and 10 non-specialised subjects] sprint cycled on a friction-loaded ergometer four maximal sprints lasting 6?s each followed by five 3-min periods of steady-state cycling at 150?W with pedalling frequencies varying from 40 to 120?rpm. The OVM and OVSM were defined as the velocities corresponding to the maximal power production and the lowest oxygen consumption, respectively. A significant linear relationship (r ² ?=?0.52, P?P?P?P?相似文献   

Effect of endurance training on different mechanical efficiency indices during submaximal cycling in subjects unaccustomed to cycling.

The purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental test and submaximal cycling exercise, at an intensity corresponding to 50% of the pretraining peak oxygen uptake, before and after 6 weeks of endurance training (18 sessions of 45 min). The training effects on efficiency indices were tested by comparisons based on GE, NE, and WE as well as by the differences between the percentage changes of all indices (%GE, %NE, %WE). Endurance training resulted in significantly higher GE (+11.1%; p < 0.001) and NE (+9.1%; p < 0.01). Only minor significant improvement (+2.4%; p < 0.05) was observed with the WE index because the value used for baseline subtraction was significantly reduced by the training sessions, due perhaps to improvement in pedaling skill. As a consequence, %WE was significantly lower than %GE (p < 0.01) and %NE (p < 0.05), while %GE and %NE were not significantly different. We conclude that mechanical efficiency of cycling increases with training in women previously unfamiliar with cycling, and that the WE index is less sensitive to this training effect than GE and NE indices.     

Pedalling rate affects endurance performance during high-intensity cycling

The purpose of this study into high-intensity cycling was to: (1) test the hypothesis that endurance time is longest at a freely chosen pedalling rate (FCPR), compared to pedalling rates 25% lower (FCPR–25) and higher (FCPR+25) than FCPR, and (2) investigate how physiological variables, such as muscle fibre type composition and power reserve, relate to endurance time. Twenty males underwent testing to determine their maximal oxygen uptake (O_2max), power output corresponding to 90% of O_2max at 80 rpm (90), FCPR at 90, percentage of slow twitch muscle fibres (% MHC I), maximal leg power, and endurance time at 90 with FCPR–25, FCPR, and FCPR+25. Power reserve was calculated as the difference between applied power output at a given pedalling rate and peak crank power at this same pedalling rate. 90 was 325 (47) W. FCPR at 90 was 78 (11) rpm, resulting in FCPR–25 being 59 (8) rpm and FCPR+25 being 98 (13) rpm. Endurance time at 90_FCPR+25 [441 (188) s] was significantly shorter than at 90_FCPR [589 (232) s] and 90_FCPR–25 [547 (170) s]. Metabolic responses such as O₂ and blood lactate concentration were generally higher at 90_FCPR+25 than at 90_FCPR–25 and 90_FCPR. Endurance time was negatively related to O_2max, 90 and % MHC I, while positively related to power reserve. In conclusion, at group level, endurance time was longer at FCPR and at a pedalling rate 25% lower compared to a pedalling rate 25% higher than FCPR. Further, inter-individual physiological variables were of significance for endurance time, % MHC I showing a negative and power reserve a positive relationship.     

Effect of exercise-induced hyperventilation on airway resistance and cycling endurance

The purpose of the present study was to investigate the effect of exercise induced hyperventilation and hypocapnia on airway resistance (R _aw), and to try to answer the question whether a reduction of R _aw is a mechanism contributing to the increase of endurance time associated with a reduction of exercise induced hyperventilation as for example has been observed after respiratory training. Eight healthy volunteers of both sexes participated in the study. Cycling endurance tests (CET) at 223 (SD 47) W, i.e. at 74 (SD 5)% of the subject's peak exercise intensity, breathing endurance tests and body plethysmograph measurements of pre- and postexercise R _aw were carried out before and after a 4-week period of respiratory training. In one of the two CET before the respiratory training CO₂ was added to the inspired air to keep its end-tidal concentration at 5.4% to avoid hyperventilatory hypocapnia (CO₂-test); the other test was the control. The pre-exercise values of specific expiratory R _aw were 8.1 (SD 2.8), 6.8 (SD 2.6) and 8.0 (SD 2.1) cm H₂O?·?s and the postexercise values were 8.5 (SD 2.6), 7.4 (SD 1.9) and 8.0 (SD 2.7) cm H₂O?·?s for control CET, CO₂-CET and CET after respiratory training, respectively, all differences between these tests being nonsignificant. The respiratory training significantly increased the respiratory endurance time during breathing of 70% of maximal voluntary ventilation from 5.8 (SD 2.9) min to 26.7 (SD 12.5) min. Mean values of the cycling endurance time (t _cend) were 22.7 (SD 6.5) min in the control, 19.4 (SD 5.4) min in the CO₂-test and 18.4 (SD 6.0) min after respiratory training. Mean values of ventilation ( ${\dot V}$ _E) during the last 3?min of CET were 123 (SD 35.8) l?·?min^?1 in the control, 133.5 (SD 35.1) l?·?min^?1 in the CO₂-test and 130.9 (SD 29.1) l?·?min^?1 after respiratory training. In fact, six subjects ventilated more and cycled for a shorter time, whereas two subjects ventilated less and cycled for a longer time after the respiratory training than in the control CET. In general, the subjects cycled longer the lower the ${\dot V}$ _E, if all three CET are compared. It is concluded that R _aw measured immediately after exercise is independent of exercise-induced hyperventilation and hypocapnia and is probably not involved in limiting t _cend, and that t _cend at a given exercise intensity is shorter when ${\dot V}$ _E is higher, no matter whether the higher ${\dot V}$ _E occurs before or after respiratory training or after CO₂ inhalation.     

Effect of isokinetic cycling versus weight training on maximal power output and endurance performance in cycling

The aim of this study was to compare the effects of a weight training program for the leg extensors with isokinetic cycling training (80 rpm) on maximal power output and endurance performance. Both strength training interventions were incorporated twice a week in a similar endurance training program of 12 weeks. Eighteen trained male cyclists (VO_2peak 60 ± 1 ml kg⁻¹ min⁻¹) were grouped into the weight training (WT n = 9) or the isokinetic training group (IT n = 9) matched for training background and sprint power (P _max), assessed from five maximal sprints (5 s) on an isokinetic bicycle ergometer at cadences between 40 and 120 rpm. Crank torque was measured (1 kHz) to determine the torque distribution during pedaling. Endurance performance was evaluated by measuring power, heart rate and lactate during a graded exercise test to exhaustion and a 30-min performance test. All tests were performed on subjects’ individual race bicycle. Knee extension torque was evaluated isometrically at 115° knee angle and dynamically at 200° s⁻¹ using an isokinetic dynamometer. P _max at 40 rpm increased in both the groups (~15%; P < 0.05). At 120 rpm, no improvement of P _max was found in the IT training group, which was possibly related to an observed change in crank torque at high cadences (P < 0.05). Both groups improved their power output in the 30-min performance test (P < 0.05). Isometric knee extension torque increased only in WT (P < 0.05). In conclusion, at low cadences, P _max improved in both training groups. However, in the IT training group, a disturbed pedaling technique compromises an improvement of P _max at high cadences.     

Influence of pedalling rate on the energy cost of cycling in humans

To determine the optimal pedalling rate that minimises both the oxygen consumption (f _V˙O2,min) and the energy cost of cycling (f _Cr,min), 22 male subjects were asked to cycle on an ergometer on five occasions of 4 min each at a constant power output of 150 W and at pedalling rates of 40, 60, 80, 100 and 120 rpm. The oxygen consumption (V˙O₂ in millilitres per minute per kilogram) and the energy cost (Cr in joules per kilogram per metre) were determined during each period. The individual V˙O₂-pedalling rate and Cr-pedalling rate relationships were fitted by parabolic regressions which allowed the determination for each individual of f _V˙O2,min [mean (SD) 57.0 (4.9) rpm] and f _Cr,min [101.1 (3.2) rpm], respectively. Contrary to the values obtained for f _V˙O2,min, those for f _Cr,min were in agreement with the pedalling rates (90–110 rpm) usually selected in road cycling. It is therefore suggested that the minimisation of Cr is the main factor that determines the pedalling rate in field conditions. The lack of a significant correlation between f _V˙O2,min and f _Cr,min further indicated that, although f _V˙O2,min is often used for determining the metabolic capacities of subjects, f _Cr,min is a better index of optimal mechanical parameters of cycling in field conditions. Electronic Publication     

Influence of two pedalling rate conditions on mechanical output and physiological responses during all-out intermittent exercise

The purpose of this study was to investigate the effect of two cycling velocities on power output and concomitant metabolic and cardiorespiratory responses to repeated all-out exercises. Mean power output (P _m), total work (W _tot), total oxygen consumption (VO_2tot) and blood lactate accumulation (Δ[La]_b) were evaluated in 13 male subjects who performed two series of twelve 5-s bouts of sprint cycling. Recovery periods of 45-s were allowed between trials. One series was executed at optimal velocity (V _opt: velocity for greatest power) and the other one at 50% V _opt (0.5V _opt). Velocities obtained in these conditions were V_opt=116.6 (4.7) rpm; 0.5V_opt=60.6 (4.9) rpm. After a phase of adaptation in oxygen uptake in the first part of the series, the data from the 6th to the 12th sprint were as follows: P _m, 924.6 (73.9) versus 689.2 (61.8) W; W _tot, 29.95 (4.14) versus 22.04 (3.17) kJ; VO_2tot, 12.80 (1.36) versus 10.58 (1.37) l; Δ[La]_b, 2.72 (1.22) versus 0.64 (0.79) mmol.l⁻¹, respectively (P<0.001). Both W _tot and VO_2tot were consistently higher at optimal velocity (+21 and +35.8%, respectively). The present findings demonstrate that during intermittent short-term all-out exercise requiring maximal activation, the energy turnover is not necessarily maximal. It depends on muscle contraction velocity. The increase, lower than expected, in metabolic response from 0.5V _opt to V _opt suggests also that mechanical efficiency is higher at V _opt. Electronic Publication     

Effect of deception and expected exercise duration on psychological and physiological variables during treadmill running and cycling

Effects of deception and expected duration on the rating of perceived exertion (RPE), affect, and heart rate (HR) were examined during treadmill (n=12) and cycling (n=8) exercise. Participants completed three conditions: (1) 20 MIN-exercise for 20 min, stop after 20 min; (2) 10 MIN-exercise for 10 min, in 10th min be told to exercise for 10 min more; and (3) UNKNOWN-no information about duration. Intensities were set at 70% and 65% of peak oxygen uptake for treadmill and cycling, respectively. RPE increased (treadmill) and affect decreased (treadmill and cycling) in the absence of changes in HR and oxygen uptake in the 10 MIN conditions. These changes suggest a disruption to a feed-forward/feedback system. The lower HR in the UNKNOWN conditions suggests a subconscious attempt to conserve energy when the duration of the exercise task is unknown.     

Evidence for freely chosen pedalling rate during submaximal cycling to be a robust innate voluntary motor rhythm

Freely chosen pedalling rate during cycling represents a voluntary rhythmic movement. It is unclear to what extent this is influenced by internal (e.g. loading on the cardiopulmonary system) and external (e.g. mechanical loading) conditions. It is also unclear just how robust a voluntary motor rhythm, the freely chosen pedalling rate, actually is. The present study investigated (N = 8) whether or not the freely chosen pedalling rate during submaximal cycling was affected by separate increases in loading on the cardiopulmonary system (changed by exposure to acute simulated altitude of 3,000 m above sea level) and mechanical loading (changed by exposure to increased power output and thereby pedal force). We also investigated (N = 7) whether or not the freely chosen pedalling rate and another voluntary motor rhythm, unimanual unloaded index finger tapping rate, shared common characteristics of steadiness and individuality over a 12-week period. Results showed that the freely chosen pedalling rate was unaffected by increased loading on the cardiopulmonary system at constant mechanical loading, and vice versa. Further, the pedalling rate was steady in the longitudinal perspective (as was the tapping rate), and like tapping rate, pedalling rate was highly individual. In total this indicated that freely chosen pedalling rate primarily is a robust innate voluntary motor rhythm, likely under primary influence of central pattern generators that again are minimally affected by internal and external conditions during submaximal cycling.     

One-legged endurance training: leg blood flow and oxygen extraction during cycling exercise

Aim: As a consequence of enhanced local vascular conductance, perfusion of muscles increases with exercise intensity to suffice the oxygen demand. However, when maximal oxygen uptake (VO₂max) and cardiac output are approached, the increase in conductance is blunted. Endurance training increases muscle metabolic capacity, but to what extent that affects the regulation of muscle vascular conductance during exercise is unknown. Methods: Seven weeks of one‐legged endurance training was carried out by twelve subjects. Pulmonary VO₂ during cycling and one‐legged cycling was tested before and after training, while VO₂ of the trained leg (TL) and control leg (CL) during cycling was determined after training. Results: VO₂max for cycling was unaffected by training, although one‐legged VO₂max became 6.7 (2.3)% (mean ± SE) larger with TL than with CL. Also TL citrate synthase activity was higher [30 (12)%; P < 0.05]. With the two legs working at precisely the same power during cycling at high intensity (n = 8), leg oxygen uptake was 21 (8)% larger for TL than for CL (P < 0.05) with oxygen extraction being 3.5 (1.1)% higher (P < 0.05) and leg blood flow tended to be higher by 16.0 (7.0)% (P = 0.06). Conclusion: That enhanced VO₂max for the trained leg had no implication for cycling VO₂max supports that there is a central limitation to VO₂max during whole‐body exercise. However, the metabolic balance between the legs was changed during high‐intensity exercise as oxygen delivery and oxygen extraction were higher in the trained leg, suggesting that endurance training ameliorates blunting of leg blood flow and oxygen uptake during whole‐body exercise.     

Effect of ambient temperature on caffeine ergogenicity during endurance exercise

It is well established that caffeine ingestion during exercise enhances endurance performance. Conversely, the physiological and psychological strain that accompanies increased ambient temperature decreases endurance performance. Little is known about the interaction between environmental temperature and the effects of caffeine on performance. The purpose of this study was to compare the effects of ambient temperature (12 and 33°C) on caffeine ergogenicity during endurance cycling exercise. Eleven male cyclists (mean ± SD; age, 25 ± 6 years; [(V)\dot] \textO_2max , {\dot V \text{O}}_{2\max } , 58.7 ± 2.9 ml kg⁻¹ min⁻¹) completed four exercise trials in a randomized, double blind experimental design. After cycling continuously for 90 min (average 65 ± 7% [(V)\dot] \textO_2max {\dot V \text{O}}_{2\max } ) in either a warm (33 ± 1°C, 41 ± 5%rh) or cool (12 ± 1°C, 60 ± 7%rh) environment, subjects completed a 15-min performance trial (PT; based on total work accumulated). Subjects ingested 3 mg kg⁻¹ of encapsulated caffeine (CAF) or placebo (PLA) 60 min prior to and after 45 min of exercise. Throughout exercise, subjects ingested water so that at the end of exercise, independent of ambient temperature, their body mass was reduced 0.55 ± 0.67%. Two-way (temperature × treatment) repeated-measures ANOVA were conducted with alpha set at 0.05. Total work (kJ) during the PT was greater in 12°C than 33°C [P < 0.001, η² = 0.804, confidence interval (CI): 30.51–62.30]. When pooled, CAF increased performance versus PLA independent of temperature (P = 0.006, η² = 0.542 CI: 3.60–16.86). However, performance differences with CAF were not dependent on ambient temperature (i.e., non-significant interaction; P = 0.662). CAF versus PLA in 12 and 33°C resulted in few differences in other physiological variables. However, during exercise, rectal temperature (T _re) increased in the warm environment (peak T _re; 33°C, 39.40 ± 0.45; 12°C, 38.79 ± 0.42°C; P < 0.05) but was not different in CAF versus PLA (P > 0.05). Increased ambient temperature had a detrimental effect on cycling performance in both the CAF and PLA conditions. CAF improved performance independent of environmental temperature. These findings suggest that caffeine at the dosage utilized (6 mg/kg body mass) is a, legal drug that provides an ergogenic benefit in 12 and 33°C.     

The effect of self- even- and variable-pacing strategies on the physiological and perceptual response to cycling

It has been proposed that an even-pacing strategy is optimal for events lasting <120 s, but this assertion is not well-established. This study tested the hypothesis that even-paced cycling is less challenging than self- or variable-paced cycling. Ten well-trained male cyclists (VO2max, 4.89 ± 0.32 L min(-1)) completed a self-paced (SP) 20-km time trial followed by time- and work-matched even-paced (EP 100% SP mean power) and variable-paced (VP 142 and 72% SP mean power, 1:1.5 high:low power ratio) trials in a random, counterbalanced order. During all trials expired air and heart rate were analysed throughout, blood lactate was sampled every 4 km, and perceptual responses (rating of perceived exertion (RPE) and affect) were assessed every 2 km and post-trial. There were no whole trial statistically significant differences between trials for any of the respiratory variables measured, although there was a trend for higher RER's in VP compared to EP (P = 0.053). Blood lactate was lower in EP compared to VP (P = 0.001) and SP (P = 0.001), and higher in SP compared to VP (P = 0.008). RPE was lower, and affect more positive, in EP compared to both SP and VP (P > 0.05). The results of this study show that, for a time- and work-matched 20-km time trial, an even-paced strategy results in attenuated perturbations in the physiological response and lower perception of effort in comparison to self- and variable-paced strategies.     

Effect of endurance training on liver cAMP response to prolonged submaximal exercise

Endurance-trained rats utilize liver glycogen at a reduced rate during exercise compared to nontrained rats. We have compared liver cAMP responses to exercise in trained and nontrained rats in an attempt to elucidate the mechanism of this adaptation. Rats were trained on a motor-driven rodent treadmill 5 days/wk for 12 wk. On the day of the test, trained and nontrained rats were quickly anesthetized after running at 21 m/min up a 15% grade for periods up to 90 min. After 45 min of running, liver cAMP had increased from 0.60 +/- 0.01 to 0.90 +/- 0.03 pmol/mg in nontrained rats whereas no significant increase had occurred in livers of trained rats. Plasma glucagon and norepinephrine levels were significantly lower in trained rats at this point. At the end of 90 min hepatic cAMP was 1.28 +/- 0.12 in nontrained compared to 0.83 +/- 0.06 pmol/mg in trained rats. Plasma glucagon was markedly elevated in nontrained but not in trained rats at this time. The lower rate of liver glycogen utilization in trained rats is consistent with the lower cAMP levels maintained early in exercise.     

Effect of internal power on muscular efficiency during cycling exercise

The purpose of this study was to investigate the muscular efficiency during cycling exercise under certain total power output (P _tot) or external power output (P _ext) experimental conditions that required a large range of pedal rates from 40 to 120 rpm. Muscular efficiency estimated as a ratio of P _tot, which is sum of internal power output (P _int) and P _ext, to rate of energy expenditure above a resting level was investigated in two experiments that featured different conditions on a cycle ergometer, which were carried out at the same levels of P _tot (Exp. 1) and P _ext (Exp. 2). Each experiment consisted of three exercise tests with three levels of pedal rates (40, 80 and 120 rpm) lasting for 2–3 min of unloaded cycling followed by 4–5 min of loaded cycling. during unloaded cycling (∼430 ml min⁻¹ for 40 rpm, ∼640 ml min⁻¹ for 80 rpm, ∼1,600 ml min⁻¹ for 120 rpm) and the P _int (∼3 W for 40 rpm, ∼25 W for 80 rpm, ∼90 W for 120 rpm) in the two experiments were markedly increased with increasing pedal rates. The highest muscular efficiency was found at 80 rpm in the two experiments, whereas a remarkable reduction (19%) in muscular efficiency obtained at 120 rpm could be attributable to greater O₂ cost due to higher levels of P _int accompanying the increased pedal rates. We concluded that muscular efficiency could be affected by the differences in O₂ cost and P _int during cycling under the large range of pedal rates employed in this study.     

Effect of human exposure to altitude on muscle endurance during isometric contractions

The aim of this study was to evaluate the influence of exposure to altitude on muscle endurance during isometric contractions. Six sedentary subjects were studied. Surface electromyograph (sEMG) activity was recorded from the right biceps brachii (BB) during exhausting isometric exercise at 80% maximal voluntary contraction. Experiments were performed before, during and 6 months after a 12 day stay at the EV-K2 laboratory (Nepal, 5,050 m above sea level). From the sEMG signals from BB, the median frequencies (f _med) were computed for consecutive 1 s epochs. The sEMG was also analysed using a non-linear tool, the recurrence quantification analysis, and the percentage of determinism (%DET) was then calculated. The haemoglobin saturation significantly decreased at altitude. The mean (SD) BB endurance time decreased from 22.4 (4) s to 18.3 (4.7) s (P<0.05). After exposure to altitude a significant variation in f _med and %DET slopes was observed. We concluded that during the first period of acclimatisation at altitude there was an impairment of isometric muscle endurance performance and there was also evidence of a modified myoelectric activity pattern suggesting a greater fatigability of the neuromuscular system. Electronic Publication     

The effect of exercise-induced muscle damage on perceived exertion and cycling endurance performance

This study evaluated the effects of exercise-induced muscle damage (EIMD) on fixed-load cycling and 5-min time-trial performance. Seven recreational athletes performed two submaximal fixed-load exercise bouts followed by a 5-min time-trial before, 48 and 168 h following 100 counter-movement jumps. Measurements of heart rate, RER and blood lactate concentration remained unchanged during the fixed-load bouts following jumping exercise. However, and increased (P < 0.05) at 48 h. RPE values were higher at 48 h as were the ratio of RPE:HR and RPE: (P < 0.05). In the time-trial, mean peak power output, mean power output, distance covered and post exercise blood lactate were lower at 48 h (P < 0.05). RPE remained unchanged between trials. These findings indicate that the ventilatory equivalent for oxygen and perceived exertion at submaximal work rates are increased 48 h following eccentric exercise. Furthermore, EIMD increases perceived exertion and impairs performance during a 5-min all-out effort.