Influence of an Added Perceptual Motor Task on Perceived Exertion: A Test of the Dissociation Effect

This experiment showed that adding a perceptual motor task to an effort session on a cycloergometer for 4 men and 4 women led to an increase in perceived exertion. This effect is opposite to the dissociative effect classically reported in the literature. These contrasting results are analyzed according to the rate of processing imposed by the added task.

Self-Perception of Fitness and Personality Traits

Our aim was to analyze how subjects perceive their own physical fitness. In Study 1 the 247 subjects assessed their own fitness, endurance, strength, flexibility, and body composition according to specific category scales. Analyses showed that self-perceived physical fitness was mainly related to perceived cardiovascular endurance. According to sex and age, strength, flexibility, and body composition could have a significant influence. The scores obtained on the five scales were highly correlated, suggesting they were overdetermined by a more general factor assimilated to physical self-worth. In Study 2 the 91 subjects completed the same five scales, the Spiel-berger State-Trait Anxiety Inventory, the Coopersmith Self-esteem Inventory, and the Bem Sex-role Inventory. Results confirmed the hierarchical model of Fox and Corbin (1989) and showed that physical self-worth is related to self-esteem, anxiety, and masculinity.

Self-Perception of Health and Fitness among French and Tunisian Men and Women

This work examines the effects of sex and culture on physical self-perceptions. The aim was to compare the perception of physical fitness of French and Tunisian men and women. 400 individuals ages 20 to 35 years assessed their own fitness, endurance, strength, flexibility, body composition, and health according to specific category scales by completing a questionnaire. In general, the Tunisian group rated themselves higher than the French group. It appears that perceived physical fitness was related mainly to perceived endurance for both groups. Some disparities were observed between the two nationalities. Analysis showed an interaction between sex and culture (French vs Tunisian). For French men and women and Tunisian men, perceived physical fitness was more associated with perceived endurance, whereas for Tunisian women, perceived physical fitness was more strongly associated with flexibility. These data show that self-perception of physical fitness is a dimension which varies between individuals from different cultures.

Accuracy and reliability of the RGB-D camera for measuring walking speed on a treadmill

AIM

RGB-D cameras (Red Green Blue+Depth) are widely employed in exergames designed to physically stimulate elderly people. Nevertheless, the intensity of the physical activity reached with the existing solutions is rarely sufficient to obtain a real impact on the physical fitness and thus on the health status of this population. In this context, a Point Cloud Based System (PCBS) has been developed to interface ordinary motorized treadmills with exergames through a simple RGB-D camera, to induce players to perform physical activities at higher intensities. The goal of this study was to assess the accuracy and reliability of PCBS to measure the walking speed of a subject on a standard motorized treadmill based on the image streams of an RGB-D camera.

METHODS

36 participants performed three 10min walking exercises, divided in 5 blocks of 2min at the following constant ordered speeds: 0.42, 0.69, 0.97, 1.25 and 1.53ms(-1). The measured walking speeds are compared to those obtained through a Marker Based Control System (MBCS).

RESULTS

Results showed a high system accuracy (bias: 0.013±0.015ms(-1)), a good reliability (ICC=0.63-0.91) and a low variability (SEM=1-5%; MD=2.7-14%).

DISCUSSION

Accuracy and reliability of PCBS are consistent with those obtained in similar existing systems measuring gait parameters.

CONCLUSION

Within the context of the development of exergames, PCBS may be combined with exergames to perform physical activities at sufficiently high intensities in the elderly population, in order to improve their physical health and possibly prevent/delay cognitive impairment.

Physiological demands of a simulated BMX competition

The aim of this study was to investigate the physiological demands of Supercross BMX in elite athletes. Firstly athletes underwent an incremental cycling test to determine maximal oxygen uptake (VO2max) and power at ventilatory thresholds. In a second phase, athletes performed alone a simulated competition, consisting of 6 cycling races separated by 30 min of passive recovery on an actual BMX track. Oxygen uptake, blood lactate, anion gap and base excess (BE) were measured. Results indicated that a simulated BMX performed by elite athletes induces a high solicitation of both aerobic (mean peak VO2 (VO2peak): 94.3±1.2% VO2max) and anaerobic glycolysis (mean blood lactate: 14.5±4. 5 mmol x L(-1) during every race. Furthermore, the repetition of the 6 cycling races separated by 30 min of recovery led to a significant impairment of the acid-base balance from the third to the sixth race (mean decrease in BE: -18.8±7.5%, p<0.05). A significant relationship was found between the decrease in BE and VO2peak (r = - 0.73, p<0.05), indicating that VO2peak could explain for 54% of the variation in BMX performance. These results suggest that both oxygen-dependent and -independent fuel substrate pathways are important determinants of BMX performance.

Variation in heart rate and blood lactate concentration in freestyle kytesurfing

AIM

The aim of this paper was to evaluate the physiological demands of freestyle kitesurfing.

METHODS

Ten elite subjects performed an incremental running test on a treadmill and a three 7 min simulated freestyle heats of kitesurfing in MW (Midwind) condition ranging from 15 to 22 knots. Oxygen uptake (VO(2)) was estimated from the heart rate (HR) recorded during the freestyle trial using the individual HR-VO(2) relationship determined during the incremental test. Blood lactate concentration [Lab] was measured at rest and 3 min after the exercise completion. 3 experienced kitesurfers acted as judges to better simulate competition conditions.

RESULTS

Linear relationship was demonstrated between scores and % HR(max) on water (r=-0.764, P<0.05), HR(max) on water (r=-0.684, P<0.05) estimated VO(2) on water (r=-0.724, P<0.05), HR on water (r=0.709, P<0.05), % VO(2) on water (r=0.740, P<0.05), final [Lab] (r=-0.884, P<0.05), anaerobic threshold (AT) (r=0.836, P<0.05), HR in AT (r=0.748, P<0.05) and ranking (r=-0,924, P<0.05), mean HR and estimated VO(2) values represented, respectively 85.4±3.0% of maximal heart rate and 80.0±4.5% of maximal oxygen uptake. Mid values for [Lab] were observed at the end of crossing trial (5.2±0.8 mmol L(-1)).

CONCLUSION

This first analysis of freestyle kitesurfing suggests that the energy demand is sustained by both aerobic and anaerobic metabolism during a MW condition and freestyle event of kitesurfing.

Age-related changes in triathlon performances

The aim of this study was two-fold: i) to analyse age-related declines in swimming, cycling, and running performances for Olympic and Ironman triathlons, and ii) to compare age-related changes in these three disciplines between the Olympic and Ironman triathlons. Swimming, cycling, running and total time performances of the top 10 males between 20 and 70 years of age (in 5 years intervals) were analysed for two consecutive world championships (2006 and 2007) for Olympic and Ironman distances. There was a lesser age-related decline in cycling performance (p<0.01) compared with running and swimming after 55 years of age for Olympic distance and after 50 years of age for Ironman distance. With advancing age, the performance decline was less pronounced (p<0.01) for Olympic than for Ironman triathlon in cycling (>55 years) and running (>50 years), respectively. In contrast, an age-related decline in swimming performance seemed independent of triathlon distance. The age-related decline in triathlon performance is specific to the discipline, with cycling showing less declines in performance with age than swimming and running. The magnitude of the declines in cycling and running performance at Ironman distance is greater than at Olympic distance, suggesting that task duration exerts an important influence on the magnitude of the age-associated changes in triathlon performance.

Assessment of physiological demand in kitesurfing

To evaluate the physiological demands of kitesurfing, ten elite subjects performed an incremental running test on a 400-m track and a 30-min on-water crossing trial during a light crosswind (LW, 12-15 knots). Oxygen uptake (V(O)(2)) was estimated from the heart rate (HR) recorded during the crossing trial using the individual HR-V(O)(2) relationship determined during the incremental test. Blood lactate concentration [La(b)] was measured at rest and 3 min after the exercise completion. Mean HR and estimated V(O)(2) values represented, respectively 80.6 +/- 7.5% of maximal heart rate and 69.8 +/- 11.7% of maximal oxygen uptake for board speeds ranging from 15 to 17 knots. Low values for [La(b)] were observed at the end of crossing trial (2.1 +/- 1.2 mmol l(-1). This first analysis of kitesurfing suggests that the energy demand is mainly sustained by aerobic metabolism during a LW condition.

Prior muscular exercise affects cycling pattern

The aim of this study was to investigate the effect of concentric or eccentric fatiguing exercise on cycling pattern. Eleven well trained cyclists completed three sessions of cycling (control cycling test [CTRL], cycling following concentric [CC] or eccentric [ECC] knee contractions) at a mean power of 276.8 +/- 26.6 Watts. Concentric and eccentric knee contractions were performed at a load corresponding to 80 % of one repetition maximum with both legs. Before and after CTRL, CC or ECC knee contractions and after cycling, a maximal voluntary contraction (MVC) test was performed. Cardiorespiratory, mechanical and electromyographic activity (EMG) of the rectus femoris, vastus lateralis and biceps femoris muscles were recorded during cycling. A significant decrease in MVC values was observed after CC and ECC exercises and after the cycling. ECC exercise induced a significant decrease in EMG root mean square during MVC and a decrease in pedal rate during cycling. EMG values of the three muscles were significantly higher during cycling exercise following CC exercise when compared to CTRL. The main finding of this study was that a prior ECC exercise induces a greater neuromuscular fatigue than a CC exercise, and changes in cycling pattern.

Relationship between strength level and pedal rate

The purpose of this study was to examine the relationship between strength capacity and preferred and optimal cadence in well trained cyclists. Eighteen cyclists participated in this study. Each subject completed three sessions. The initial session was to evaluate the maximal isokinetic voluntary contraction level of lower limb. The second session was an incremental test to exhaustion. During the third session subjects performed a constant cycling exercise (20 min) conducted at five randomly cadences (50, 70, 90, 110 rpm) and at the preferred cadence (FCC) at the power reached at ventilatory threshold. Cardiorespiratory and EMG values were recorded. A metabolic optimum (EOC) was observed at 63.5 +/- 7.8 rpm different from preferred cadence (FCC, 90.6 +/- 9.1 rpm). No difference was found between FCC and the neuromuscular optimal cadence (NOC, 93.5 +/- 4). Significant relationships were found between EOC, NOC and strength capacities (r = - 0.75 and - 0. 63), whereas FCC was only related with VO2max (r = 0.59). The main finding of this study was that during submaximal cycling energetically optimal cadence or neuromuscular optimum in trained cyclists was significantly related with strength capacity and whereas preferred cadence seems to be related with endurance training status of cyclists.

Is impairment similar between arm and leg cranking exercise in COPD patients?

Impaired skeletal muscle function has been reported in patients with chronic obstructive disease (COPD), but such impairment is not homogenous and its distribution between the upper and the lower limbs is still unclear. The present study was designed to assess and compare upper and lower limb capacities in patients with moderate to severe COPD during incremental and constant-load exercises. Thirteen COPD patients of similar age with moderate to severe air flow limitation (FEV(1): 35%+/-5% predicted) and 19 healthy subjects were studied. Four sessions were organized: two incremental and two constant-load cycling exercises with arm or leg in randomized order. As observed in a previous study involving incremental and constant tests, power, VO(2), RER, VE, and HR were all significantly lower in the upper and lower limbs of patients with COPD than in healthy controls. In the healthy population, aerobic capacity and mechanical efficiency (ME) were lower in the course of arm exercises than in leg exercises. For the same relative workload, dyspnea and blood lactate production were higher during arm exercise. In contrast, no significant difference was observed between arm and leg capacities for any of these parameters in COPD patients.

CONCLUSION

Although aerobic capacity is impaired in COPD patients, arm aerobic capacity is relatively preserved. Given the lack of significant difference between arm and leg capacities in COPD, we hypothesize that upper limb muscles are less compromised than lower limb muscles in this patient population.

The assessment of energy demand in the new Olympic windsurf board: Neilpryde RS:X

The aim of this study was to evaluate the energy demands of sailing the new Neilpryde RS:X Olympic windsurf board. Ten skilled male subjects performed an exhaustive incremental treadmill test to determine their maximal physiological parameters. Thereafter, four tests were performed in a randomised order using two wind conditions, light [2-4 ms(-1) (4-8 knots)] and strong: [9-11 ms(-1)(16-22 knots)]. Oxygen consumption (VO2, ml min(-1) kg(-1)), blood lactate concentration ([la](b), mmol l(-1)), and time spent pumping (% total time) were recorded during 10 min of up-wind leg and during 6 min of down-wind leg. The results indicate that sailing on RS:X is associated with a high level of energy demand using both aerobic and anaerobic pathways whatever the wind conditions. During the down-wind leg, VO2, (ml min(-1) kg(-1)), [la](b) (mmol l(-1)), and time spent pumping (% total time) values for the light and strong wind conditions were 56.5 +/- 5.9 versus 55.5 +/- 3.6; 10.2 +/- 1.5 versus 9.6 +/- 2.3, and 69 +/- 5 versus 64 +/- 2%, respectively. In contrast, during up-wind leg the same parameters for light and strong wind were 53.9 +/- 4.5 versus 40.4 +/- 7.2; 9.7 +/- 2.8 versus 5.0 +/- 2.7 and 66 +/- 3 versus 37 +/- 8%, respectively. During the up-wind leg with strong wind conditions, less time was spent pumping (p < 0.05), mean oxygen consumption values were close to 60% VO2max and post-exercise blood lactate was less than 50% maximal lactate concentration. These results could be related to the time spent in pumping action, involving whole body activity. When sailing with the RS:X board, the physiological demand seems to be higher than with the previous official Olympic windsurf board [Mistral One Design (MOD)]. This difference could be mainly attributed to the specific biomechanical constraints induced by each board characteristic.

Assessment of energy demand in Laser sailing: influences of exercise duration and performance level

In this study we analyzed the influence of both exercise duration and skill level on energy demand in Laser sailing. Twenty-three subjects volunteered for this study. The population is divided into two groups according to their skill level: 13 high (HS) and 10 low (LS). Every subject performed a 30 min upwind sailing test, with a tacking every 2 min. Heart rate (HR), gas exchange and respiratory parameters were analyzed throughout the trial, and measured blood lactate concentration ([La(bl)] at rest and immediately after the exercise completion. Three, 4 min intervals were selected for analysis: 6-10 min (T10), 16-20 min (T20) and 26-30 min (T30). In contrast to previous studies, we found significantly progressive aerobic energy metabolism with sailing duration in the HS group (T10 = 45%; T20 = 61%; T30 = 68% VO2max, P < 0.05), whereas this demand remained stable, and significantly lower in LS group (T10 = 45%; T20 = 52%; T30 = 51% VO2max, P < 0.05). This study shows that aerobic demand is significantly more important in LS than in HS subjects after 30 min regatta, and could be an important factor in Laser regatta performance. We need further studies to confirm and explain this difference.

Variable power output during cycling improves subsequent treadmill run time to exhaustion

The aim of this study was to investigate the effect of constant versus variable power output cycling exercise on subsequent high-intensity, running performance. Eight triathletes completed two testing sessions (in a random order), which required the subjects to perform 30 min of cycling at either, a constant power output (90% of the lactate threshold), or a variable power output with power output alternating every 5 min (+/-20% of the constant workload). Each cycling bout was immediately followed by a high-intensity treadmill run (16.7+/-0.7 km h(-1)) to exhaustion. No significant differences were found for mean metabolic values or power output between cycling conditions. However, a significant (P<0.05) improvement in run time to exhaustion was reported after 30 min of variable cycling (15:09+/-4:43 min) compared to constant cycling (10:51+/-3:32 min). The results of this study demonstrate that, despite similar average physiological responses during 30 min of cycling, variable-intensity cycling results in an improved running performance compared to constant-intensity cycling. It is hypothesised that the reduced power output in the final 5 min of variable cycling protocol may allow recovery before transition, however the mechanisms involved cannot be determined from the current study.

Cadence selection affects metabolic responses during cycling and subsequent running time to fatigue

OBJECTIVES

To investigate the effect of cadence selection during the final minutes of cycling on metabolic responses, stride pattern, and subsequent running time to fatigue.

METHODS

Eight triathletes performed, in a laboratory setting, two incremental tests (running and cycling) to determine peak oxygen uptake (VO2PEAK) and the lactate threshold (LT), and three cycle-run combinations. During the cycle-run sessions, subjects completed a 30 minute cycling bout (90% of LT) at (a) the freely chosen cadence (FCC, 94 (5) rpm), (b) the FCC during the first 20 minutes and FCC-20% during the last 10 minutes (FCC-20%, 74 (3) rpm), or (c) the FCC during the first 20 minutes and FCC+20% during the last 10 minutes (FCC+20%, 109 (5) rpm). After each cycling bout, running time to fatigue (Tmax) was determined at 85% of maximal velocity.

RESULTS

A significant increase in Tmax was found after FCC-20% (894 (199) seconds) compared with FCC and FCC+20% (651 (212) and 624 (214) seconds respectively). VO2, ventilation, heart rate, and blood lactate concentrations were significantly reduced after 30 minutes of cycling at FCC-20% compared with FCC+20%. A significant increase in VO2 was reported between the 3rd and 10th minute of all Tmax sessions, without any significant differences between sessions. Stride pattern and metabolic variables were not significantly different between Tmax sessions.

CONCLUSIONS

The increase in Tmax after FCC-20% may be associated with the lower metabolic load during the final minutes of cycling compared with the other sessions. However, the lack of significant differences in metabolic responses and stride pattern between the run sessions suggests that other mechanisms, such as changes in muscular activity, probably contribute to the effects of cadence variation on Tmax

Influence of Exercise Duration and Hydration Status on Cognitive Function During Prolonged Cycling Exercise

The purpose of the present study was to examine the influence of submaximal aerobic exercise duration on simple and complex cognitive performance. Eight well-trained male subjects agreed to participate in this study (trial group). A control group of eight regularly trained male subjects was included for comparative purposes. For the trial group, the experiment involved a critical flicker fusion test (CFF) and a map recognition task performed before, every 20 min during, and immediately after, a 3-h cycling task at an intensity corresponding to approximately 60 % of VO2max. Data were obtained over two experimental sessions with fluid ingestion (F) or no fluid (NF) ingestion. For the control group the experiment was the same but without exercise and fluid ingestion. In the trial group, a significant effect of hydration status was observed on physiological parameters (p <0.05). No effect was found on cognitive performance. A significant decrease in CFF performance was observed after 120 min of exercise when compared with the first 20 min (respectively for CFFmdi: 2.6 vs. 3.8 Hz), irrespective of experimental condition. A significant improvement in speed of response (respectively: 3291 vs. 3062 msec for 20 and 120 min, respectively) and a decrease in error number (21.5 % vs. 6.0 % for 20 and 120 min, respectively) during the map recognition task were recorded between 80 min and 120 min when compared with the first 20 min of exercise. After 120 min the number of recorded errors was significantly greater indicating a shift in the accuracy-speed trade-off (6.0 % vs. 14.1 % for 120 and 180 min, respectively). These results provide some evidence for exercise-induced facilitation of cognitive function. However this positive effect disappears during prolonged exercise--as evidenced within our study by an increase in errors during the complex task and an alteration in perceptual response (i.e. the appearance of symptoms of central fatigue).

Effect of long duration exercise on the ratings of perceived exertion and perceived difficulty of walking and running at the ventilatory threshold

AIM

The purpose of this study was to examine if the relationship between physiological changes classically observed with exercise duration and some subjective workload measures would be affected by the complexity of the locomotion mode (running vs racewalking).

METHODS

The study was conducted on 24 well trained subjects (12 long distance runners and 12 racewalkers) divided in 3 groups (runners, racewalkers and control). Energy cost of locomotion (C), heart rate (HR), minute ventilation (V(E)), lactate concentration [La], ratings of perceived exertion (RPE 6-20 scale) and ratings of perceived difficulty (RPD 1(-1)5 scale) were recorded during 2 10-min submaximal tests on a treadmill before and immediately after a 3 hour exercise (racewalking or running) conducted at the velocity ventilatory threshold (vVT).

RESULTS

No significant variations in physiological parameters and perceived measures were observed in G(c). A significant increase (p<0.05) in energy cost of walking (mean: +9.4%) and running (mean: +7.5%) at the end of exercise was observed. A significant interaction of locomotion mode and exercise duration was found on perceived exertion and perceived difficulty. In racewalkers RPD significantly increased with duration whereas no significant effect was found for RPE. Conversely a significant increase in RPE was found after 3 hours in runners without any significant change in RPD.

CONCLUSIONS

This experiment suggests that, for a complex task, the classical relationship between RPE and metabolic load increase during prolonged exercise could be affected by changes in RPD. In this study, stability in RPE and increase in RPD observed in racewalkers may reflect an attentional focus dissociated from internal sensations and directed toward maintaining the required race walking gait.

Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes

OBJECTIVES

To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes.

METHODS

Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% VO(2)max).

RESULTS

A significant effect of the prior cycling exercise was found on middle distance running performance without any cadence effect (625.7 (40.1), 630.0 (44.8), 637.7 (57.9), and 583.0 (28.3) seconds for the 60 rpm run, 80 rpm run, 100 rpm run, and isolated run respectively). However, during the first 500 m of the run, stride rate and running velocity were significantly higher after cycling at 80 or 100 rpm than at 60 rpm (p<0.05). Furthermore, the choice of 60 rpm was associated with a higher fraction of VO(2)max sustained during running compared with the other conditions (p<0.05).

CONCLUSIONS

The results confirm the alteration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of the cadence was observed within the range usually used by triathletes.

Influence of drafting during swimming on ratings of perceived exertion during a swim-to-cycle transition in well-trained triathletes

After the swim to cycle transition of a triathlon, perceived exertion (RPE) during cycling was higher than during a single cycling bout for 8 well-trained triathletes, but swimming in a drafting position led to lower RPE responses and energy cost of cycling than swimming alone.

Influence of physical exercise on perceptual response in aerobically trained subjects

A significant effect of fatigue induced byphysical exercise leading to exhaustion was observed for 6 male triathletes using some specific analysis of the critical flicker fusion test.

Single and choice reaction time during prolonged exercise in trained subjects: influence of carbohydrate availability

The aim of the present study was to examine the effects of prolonged exercise at the ventilatory threshold and carbohydrate ingestion on single (SRT) and choice (CRT) reaction time. Eight well-trained triathletes completed three testing sessions within a 3-week period. Maximal oxygen uptake was determined in the first test, whereas the second and the third sessions were composed of a 100-min run (treadmill 15 min, overground 70 min, treadmill 15 min) performed at the velocity associated with the ventilatory threshold. During these submaximal tests, the subjects ingested (in random order) 8 ml x kg(-1) body weight of either a placebo (Pl) or 5.5% carbohydrate (CHO) solution prior to the first submaximal run and 2 ml x kg(-1) body weight every 15 min after that. The cognitive tasks were performed before and after exercise for CRT, and before, during each submaximal run and after exercise for SRT. Furthermore, at the end of each submaximal test subjects were asked to report their rating of perceived exertion (RPE). Results showed a significant positive effect of CHO ingestion on RPE and CRT performance at the end of exercise, while no effect of exercise duration was found in the Pl condition. After a 100-min run, during the CHO condition, CRT mean (SD) group values decreased from 688.5 (51) ms to 654 (63) ms, while during the Pl condition, RPE mean group values increased from 11 (2) to 16 (1.02) and CRT mean values remained stable [688 (104) ms vs 676 (73.4) ms, P > 0.05]. No similar effect was observed for SRT. These results suggest that CHO-electrolyte ingestion during a 100-min run results in an improvement in the complex cognitive performance measured at the end of that run.

Effects of a prolonged run on simple reaction time of well trained runners

The aim of the present study was to examine the effect of increased arousal induced by a prolonged exercise at ventilatory threshold simple reaction time performance performed during a running task. 11 well trained triathletes completed two testing sessions within a 2-wk. period. The first session was a protocol of VO2 max determination conducted on a treadmill. This protocol was used to assess the velocity associated with ventilatory threshold (vVvt). The second session was a 90-min. running test performed at vVvt. This last session was composed of five submaximal treadmill runs (10-min. long, 0% grade) separated by four overground runs (10-min.). Before, during each treadmill run, and after exercise, subjects performed three blocks of 20 simple reaction time. Furthermore, at the end of each overground run, perceived exertion (RPE) was recorded. Analysis showed a significant impairment in Simple RT performance during the first treadmill run only. After this first run a significant effect of exercise duration on Simple RT was observed. After 40-min. of exercise a significant improvement in reaction time during exercise was recorded, Furthermore, when Simple RT was recorded at rest, there was no difference pre-exercise and postexercise. These results suggest that a simple cognitive performance could be improved during exercise, despite the negative effect of the dual task. This improvement in reaction time could be explained mainly by an increase in arousal induced by a prolonged exercise.

Effect of pedalling rates on physiological response during endurance cycling

This study was undertaken to examine the effect of different pedalling cadences upon various physiological responses during endurance cycling exercise. Eight well-trained triathletes cycled three times for 30 min each at an intensity corresponding to 80% of their maximal aerobic power output. The first test was performed at a freely chosen cadence (FCC); two others at FCC - 20% and FCC + 20%, which corresponded approximately to the range of cadences habitually used by road racing cyclists. The mean (SD) FCC, FCC - 20% and FCC + 20% were equal to 86 (4), 69 (3) and 103 (5) rpm respectively. Heart rate (HR), oxygen uptake (VO2), minute ventilation (VE) and respiratory exchange ratio (R) were analysed during three periods: between the 4th and 5th, 14th and 15th, and 29th and 30th min. A significant effect of time (P < 0.01) was found at the three cadences for HR, VO2. The VE and R were significantly (P < 0.05) greater at FCC + 20% compared to FCC - 20% at the 5th and 15th min but not at the 30th min. Nevertheless, no significant effect of cadence was observed in HR and VO2. These results suggest that, during high intensity exercise such as that encountered during a time-trial race, well-trained triathletes can easily adapt to the changes in cadence allowed by the classical gear ratios used in practice.

Effect of two drafting modalities in cycling on running performance

PURPOSE

The purposes of this study were first to compare the physiological responses during a triathlon where cycling was performed alternatively with another cyclist (alternate draft triathlon, ADT) or continuously behind him (continuous draft triathlon, CDT), and second to study the incidence of these two drafting modalities in cycling on the subsequent running performance done during a simulated triathlon.

METHODS

Ten male triathletes of national level performed a sprint distance triathlon (0.75-km swim, 20-km bike, 5-km run) on two different sessions, one where the triathlete alternatively rode in front or at the back of another cyclist and rotating every 500 m, the other where the triathlete drafted continuously a professional cyclist whose task was to reproduce all split times recorded during the alternate situation. Oxygen uptake (VO2), expiratory flow (VE), heart rate (HR) were recorded during the entire bike and run sections and blood lactate concentrations ([La-]b) were analyzed at the end of each event composing the triathlon.

RESULTS

The results showed that expiratory flow, oxygen uptake, heart rate and blood lactate concentrations were significantly lower in CDT on the bike compared with drafting in alternation (148.1 vs. 167.2 L.min-1, 49.9 vs. 59.8 mL.min-1.kg-1, 154.7 vs. 173.1 beats.min-1, 3.5 vs. 6.3 mmol.L-1, respectively). The results also revealed that running after biking in CDT (for similar cycling speeds) significantly improved the subsequent running speed compared to ADT (17.87 vs. 17.15 km.h-1). Furthermore, VE, VO2, HR, and [La-]b were significantly higher during CDT run compared with ADT run (175.6 vs. 170.4 L.min-1, 69.7 vs. 66.8 mL.min-1.kg-1, 182.6 vs. 177.3 beats.min-1, 9.6 vs. 7.5 mmol.L-1, respectively).

CONCLUSIONS

These results showed that drafting continuously behind a lead cyclist allows triathletes to save a significant amount of energy during the bike leg of a sprint triathlon and creates the conditions for an improved running performance compared with a situation where cycling is performed alternating the lead with another cyclist.

Effect of exercise duration on optimal pedaling rate choice in triathletes

The purpose of this study was to investigate the effect of an exercise duration similar to triathlon's cyclism event (approximately 1 hr), on factors determining the freely chosen cadence. Nine trained triathletes completed a cycling track session conducted at a speed corresponding to 75% of maximal heart rate. This session was composed of five submaximal rides performed at five cadences presented in a random order (65, 80, 95, 110 rpm and freely chosen cadence) realized before and after a 1-hr exercise at the freely chosen cadence. Results show, during the first condition, that triathletes choose spontaneously a cadence (90,1 +/- 10,7 rpm) close to the neuromuscular optimum (89,6 +/- 1,1 rpm) while at the end of exercise, a decrease of the freely chosen cadence (82,8 +/- 8,7 rpm) was observed toward the energetically optimal cadence (78,6 +/- 5,8 rpm). These findings suggest the hypothesis of an adaptation of the movement pattern with the exercise duration in order to minimize the energy cost rather than the neuromuscular cost of cycling.