Influence of gender on pacing adopted by elite triathletes during a competition

The aim of this study was to compare the pacing strategies adopted by women and men during a World Cup ITU triathlon. Twelve elite triathletes (6 females, 6 males) competed in a World Cup Olympic distance competition where speed and heart rate (HR) were measured in the three events. The power output (PO) was recorded in cycling to determine the time spent in five intensity zones ([0–10% VT1]; [10% VT1–VT1]; [VT1–VT2]; [VT2–MAP] and ≥MAP) [ventilatory threshold (VT); maximal aerobic power (MAP)]. Swimming and running speeds decreased similarly for both genders (P < 0.05) and HR values were similar through the whole race (92 ± 2 and 92 ± 3% of maximal HR for women and men, respectively). The distribution of time spent in the five zones during the cycling leg was the same for both genders. The men’s speed and PO decreased after the first bike lap (P < 0.05) and the women spent relatively more time above MAP in the hilly sections (45 ± 4 vs. 32 ± 4%). The men’s running speed decreased significantly over the whole circuit, whereas the women slowed only over the uphill and downhill sections (P < 0.05). This study indicates that both female and male elite triathletes adopted similar positive pacing strategies during swimming and running legs. Men pushed the pace harder during the swim-to-cycle transition contrary to the women and female triathletes were more affected by changes in slope during the cycling and running phases.     

The influence of prior cycling on biomechanical and cardiorespiratory response profiles during running in triathletes

The aim of the present study was to determine the effects of 40 km of cycling on the biomechanical and cardiorespiratory responses measured during the running segment of a classic triathlon, with particular emphasis on the time course of these responses. Seven male triathletes underwent four successive laboratory trials: (1) 40 km of cycling followed by a 10-km triathlon run (TR), (2) a 10-km control run (CR) at the same speed as TR, (3) an incremental treadmill test, and (4) an incremental cycle test. The following ventilatory data were collected every minute using an automated breath-by-breath system: pulmonary ventilation (V˙ _E, l · min⁻¹), oxygen uptake (V˙O₂, ml · min⁻¹ · kg⁻¹), carbon dioxide output (ml · min⁻¹), respiratory equivalents for oxygen (V˙ _E/V˙O₂) and carbon dioxide (V˙ _E/V˙CO₂), respiratory exchange ratio (R) respiratory frequency (f, breaths · min⁻¹), and tidal volume (ml). Heart rate (HR, beats · min⁻¹) was monitored using a telemetric system. Biomechanical variables included stride length (SL) and stride frequency (SF) recorded on a video tape. The results showed that the following variables were significantly higher (analysis of variance, P < 0.05) for TR than for CR: V˙O₂ [51.7 (3.4) vs 48.3 (3.9) ml · kg⁻¹ · min⁻¹, respectively], V˙ _E [100.4 (1.4) l · min⁻¹ vs 84.4 (7.0) l · min⁻¹], V˙ _E/V˙O₂ [24.2 (2.6) vs 21.5 (2.7)] V˙ _E/V˙CO₂ [25.2 (2.6) vs 22.4 (2.6)], f [55.8 (11.6) vs 49.0 (12.4) breaths · min⁻¹] and HR [175 (7) vs 168 (9) beats · min⁻¹]. Moreover, the time needed to reach steady-state was shorter for HR and V˙O₂ (1 min and 2 min, respectively) and longer for V˙ _E (7 min). In contrast, the biomechanical parameters, i.e. SL and SF, remained unchanged throughout TR versus CR. We conclude that the first minutes of the run segment after cycling in an experimental triathlon were specific in terms of V˙O₂ and cardiorespiratory variables, and nonspecific in terms of biomechanical variables. Accepted: 7 July 1997     

Effects of loading on upper airway and respiratory pump muscle motoneurons

The functional outcomes of respiratory muscle loading by chemical (e.g. hypercapnia), mechanical (i.e. external mechanical loading) or ventilatory (e.g. exercise) factors can be either positive, such as through an increase in pressure-generating capacity of the inspiratory muscles or detrimental, such as by fatigue. Neurophysiological responses to respiratory muscle loading can occur at one or more points along the pathway from motor cortex to muscle. This paper describes the respiratory pump and upper airway motoneuron responses to the imposition of acute loads including processes of pre-activation, respiratory reflexes, potentiation and fatigue. It also considers changes suggestive of adaptation to chronic loading either from specific respiratory muscle training programs or as part of disease processes such as chronic obstructive pulmonary disease or obstructive sleep apnoea.     

The effects of 3000-m swimming on subsequent 3-h cycling performance: implications for ultraendurance triathletes

The purpose of this study was to examine the physiological effects of 3000-m swimming on subsequent 3-h cycling time trial performance in ultraendurance triathletes. Eight highly trained ultraendurance triathletes [mean (SEM) age 34 (2) years, body fat 12.5 (0.8)%, maximum oxygen consumption 63.2 (2.1) ml · kg⁻¹ · min⁻¹] completed two randomly assigned trials 1 week apart. The swim/bike trial (SB) involved 3000 m of swimming [min:s 52:28 (1:48)] immediately followed by a 3-h cycling performance at a self-selected time-trial pace. The control trial (CON) consisted of an identical 3-h cycling time trial but without prior swimming. Subjects consumed an 8% carbohydrate (CHO)/electrolyte beverage during both trials at the rate of 60 g CHO · h⁻¹ and 1 l · h⁻¹. No significant differences were evident between CON and SB on the dependent measures (CON vs SB): power output [W˙, 222 (14) W vs 212 (13) W], heart rate [f _c, 147 (5) beats · min⁻¹ vs 143 (4) beats · min⁻¹; %f _cmax 80.0 (1.6)% vs 78.4 (1.5)%], oxygen uptake [3.10 (0.12) l · min⁻¹ vs 2.97 (0.15) l · min⁻¹], minute ventilation [82.5 (4.4) l · min⁻¹ vs 77.3 (3.7) l · min⁻¹], rating of perceived exertion [14.6 (0.4) vs 14.0 (0.1)], blood lactate [6.1 (0.5) mmol · l⁻¹ vs 4.8 (0.5) mmol · l⁻¹], and blood glucose [5.0 (0.2) mmol · l⁻¹ vs 5.3 (0.1) mmol · l⁻¹; all non-significant at the P > 0.05 level]. However, the CON respiratory exchange ratio was significantly greater than for SB [0.91 (0.01) vs 0.89 (0.01); P < 0.05], suggesting that the SB trial required a greater reliance on lipid as a fuel substrate. Hence, the main finding in the present study was that 3000 m of swimming had no significant performance effect (in terms of W˙) on subsequent 3-h cycling performance in ultraendurance triathletes. Accepted: 2 March 2000     

The role of anaerobic ability in middle distance running performance

Summary The purpose of this study was to assess the relationship between anaerobic ability and middle distance running performance. Ten runners of similar performance capacities (5 km times: 16.72, SE 0.2 min) were examined during 4 weeks of controlled training. The runners performed a battery of tests each week [maximum oxygen consumption (VO_2max), vertical jump, and Margaria power run] and raced 5 km three times (weeks 1, 2, 4) on an indoor 200-m track (all subjects competing). Regression analysis revealed that the combination of time to exhaustion (TTE) during theVO_2max test (r ²=0.63) and measures from the Margaria power test (W·kg^–1,r ²=0.18 ; W,r ²=0.05) accounted for 86% of the total variance in race times (P<0.05). Regression analysis demonstrated that TTE was influenced by both anaerobic ability [vertical jump, power (W·kg^–1) and aerobic capacity (VO_2max, ml·kg^–1·min^–1)]. These results indicate that the anaerobic systems influence middle distance performance in runners of similar abilities.     

Effects of the order of running and cycling of similar intensity and duration on pulmonary diffusing capacity in triathletes

To study the pathophysiological mechanisms involved in the decrease of post-triathlon diffusing capacity (DLco), blood rheologic properties (blood viscosity: _b; changes in plasma volume: PV) and atrial natriuretic factor (ANF) were assessed in ten triathletes during cycle-run (CR) and run-cycle (RC) trials at a metabolic intensity of 75% of maximal oxygen consumption (O_2max). The DLco was measured before and 10 min after trials. ANF and PV were measured at rest, after the cycle and run of CR and RC trials, and at the end of and 10 min after exercise. RC led to a greater DLco decrease, a lower ANF concentration and a lower PV than did CR, whereas for both CR and RC _b was increased throughout exercise and 10 min after. In addition, after CR the DLco decrease was inversely correlated (r=–0.764; P<0.01) with PV. The association of decreased plasma volume, increased _b, and lower ANF concentrations after RC suggested that lower blood pulmonary volume may have caused the greater decrease in Dlco as compared with CR. The inverse correlation between PV and DLco reinforces the hypothesis that fluid shifts limit the post-exercise DLco decrease after the CR succession in triathletes. Lastly, cycling in the crouched position might increase intra-thoracic pressure, decrease thorax volume due to the forearm position on the handlebars, and weaken peripheral muscular pump efficacy, all of which would limit venous return to the heart, and thus result in low pulmonary blood volume. Compared with cycling, running appeared to induce the opposite effects.     

The effect of endurance training on the ventilatory response to exercise in elite cyclists

The purpose of this study was to investigate the effects of endurance training on the ventilatory response to acute incremental exercise in elite cyclists. Fifteen male elite cyclists [mean (SD) age 24.3 (3.3) years, height 179 (6) cm, body mass 71.1 (7.6) kg, maximal oxygen consumption (V˙O_2max) 69 (7) ml · min⁻¹ · kg⁻¹] underwent two exercise tests on a cycle ergometer. The first test was assessed in December, 6 weeks before the beginning of the cycling season. The second test was performed in June, in the middle of the season. During this period the subjects were expected to be in a highly endurance-trained state. The ventilatory response was assessed during an incremental exercise test (20 W · min⁻¹). Oxygen consumption (V˙O₂), carbon dioxide production (V˙CO₂), minute ventilation (V˙ _E), and heart rate (HR) were assessed at the following points during the test: at workloads of 200 W, 250 W, 300 W, 350 W, 400 W and at the subject's maximal workload, at a respiratory exchange ratio (R) of 1, and at the ventilatory threshold (Th_vent) determined using the V-slope-method. Post-training, the mean (SD) V˙O_2max was increased from the pre-training level of 69 (7) ml · min⁻¹ · kg⁻¹ (range 61.4–78.6) to 78 (6) ml · min⁻¹ · kg⁻¹ (range 70.5–86.3). The mean post-training V˙O₂ was significantly higher than the pre training value (P < 0.01) at all work rates, at Th_vent and at R=1. V˙O₂ was also higher at all work rates except for 200 W and 250 W. V˙ _E was significantly higher at Th_vent and R=1. Training had no effect on HR at all workloads examined. An explanation for the higher V˙O₂ cost for the same work rate may be that in the endurance-trained state, the adaptation to an exercise stimulus with higher intensity is faster than for the less-trained state. Another explanation may be that at the same work rate, in the less-endurance-trained state power is generated using a significantly higher anaerobic input. The results of this study suggest the following practical recommendations for training management in elite cyclists: (1) the V˙O₂ for a subject at the same work rate may be an indicator of the endurance-trained state (i.e., the higher the V˙O₂, the higher the endurance-trained capacity), and (2) the need for multiple exercise tests for determining the HR at Th_vent during a cycling season is doubtful since at Th_vent this parameter does not differ much following endurance training. Accepted: 19 October 1999     

Effects of concurrent inspiratory and expiratory muscle training on respiratory and exercise performance in competitive swimmers

The efficiency of the respiratory system presents significant limitations on the bodys ability to perform exercise due to the effects of the increased work of breathing, respiratory muscle fatigue, and dyspnoea. Respiratory muscle training is an intervention that may be able to address these limitations, but the impact of respiratory muscle training on exercise performance remains controversial. Therefore, in this study we evaluated the effects of a 12-week (10 sessions week^–1) concurrent inspiratory and expiratory muscle training (CRMT) program in 34 adolescent competitive swimmers. The CRMT program consisted of 6 weeks during which the experimental group (E, n=17) performed CRMT and the sham group (S, n=17) performed sham CRMT, followed by 6 weeks when the E and S groups performed CRMT of differing intensities. CRMT training resulted in a significant improvement in forced inspiratory volume in 1 s (FIV_1.0) (P=0.050) and forced expiratory volume in 1 s (FEV_1.0) (P=0.045) in the E group, which exceeded the S groups results. Significant improvements in pulmonary function, breathing power, and chemoreflex ventilation threshold were observed in both groups, and there was a trend toward an improvement in swimming critical speed after 12 weeks of training (P=0.08). We concluded that although swim training results in attenuation of the ventilatory response to hypercapnia and in improvements in pulmonary function and sustainable breathing power, supplemental respiratory muscle training has no additional effect except on dynamic pulmonary function variables.     

Cardiac vagal tone, exercise performance and the effect of respiratory training

Heart rate variability (HRV) at rest and heart rate recovery after exercise reflect cardiac vagal activity. The aim of this study was to determine whether increasing HRV during involuntary respiratory training induced by rebreathing air using a Hepburn heart and lung exerciser (HHALE) could, like exercise, improve vagal tone. Eighteen subjects (36–88 years) underwent a 6-week control period, then a 6-week training period with the HHALE following which half continued training for 6 weeks and half ceased training. Measurements were made of HRV, work at 60% predicted heart rate max for 15 min, heart rate recovery after exercise, resting blood pressure, heart rate, vital capacity and forced expiratory volume. After the first 6-week HHALE training, there was a significant increase of 13.2±5.7 in the high frequency peak of the power spectrum of HRV at rest, whereas, the low frequency peak decreased. Similarly, exercise performance showed a significant improvement of 0.031±0.012 J per heartbeat from a pre-training 0.128±0.022. Also, heart rate recovery after exercise significantly faster (drop in the first 20 s improving by 3.3±1.5 beats from a pre-training 12.9±1.6). The subgroup that continued training maintained or slightly improved these values. In those that ceased training the speed of heart rate recovery at the end of the exercise test returned to pre-trained levels, whereas, other responses were either maintained or decreased slightly. We conclude that training with the HHALE can, without additional exercise, increase cardiac vagal tone and exercise performance.     

The influence of inspiratory and expiratory muscle training upon rowing performance

We investigated the effect of 4 week of inspiratory (IMT) or expiratory muscle training (EMT), as well as the effect of a subsequent 6 week period of combined IMT/EMT on rowing performance in club-level oarsmen. Seventeen male rowers were allocated to either an IMT (n = 10) or EMT (n = 7) group. The groups underwent a 4 week IMT or EMT program; after interim testing, both groups subsequently performed a 6 week program of combined IMT/EMT. Exercise performance and physiological responses to exercise were measured at 4 and 10 week during an incremental rowing ergometer ‘step-test’ and a 6 min all-out (6MAO) effort. Pressure threshold respiratory muscle training was undertaken at the 30 repetition maximum load (∼50% of the peak inspiratory and expiratory mouth pressure, P _Imax or P _Emax, respectively). P _Imax increased during the IMT phase of the training in the IMT group (26%, P < 0.001) and was accompanied by an improvement in mean power during the 6MAO (2.7%, P = 0.015). Despite an increase in P _Emax by the end of the intervention (31%, P = 0.03), the EMT group showed no significant changes in any performance parameters during either the ‘step-test’ or 6MAO. There were no significant changes in breathing pattern or the metabolic response to the 6MAO test in either group, but the IMT group showed a small decrease in HR (2–5%, P = 0.001). We conclude that there were no significant additional changes following combined IMT/EMT. IMT improved rowing performance, but EMT and subsequent combined IMT/EMT did not.     

The effects of drafting on stroking variations during swimming in elite male triathletes

The aim of this study was to determine the effects of drafting behind another swimmer on the metabolic response and stroke characteristics. Six highly trained male triathletes performed two maximal 400-m swims, one in a drafting (D) and one in a non-drafting condition (ND). Their metabolic response was assessed by measuring the oxygen uptake (V˙O₂) and the blood lactate concentration at the end of each 400 m. Swimming velocity, stroke frequency, stroke length, and stroke index (velocity multiplied by stroke length) were recorded every 50 m. In the D and ND conditions, there was no difference in V˙O₂ [66.7 (1.7) ml · kg⁻¹ · min⁻¹ vs 65.6 (1.2) ml · kg⁻¹ · min⁻¹, respectively], however, the lactate concentrations were lower in D than in ND [9.6 (0.9) mM vs 10.8 (0.9) mM, respectively, P < 0.01]. In D, the performance [1.39 (0.02) m · s⁻¹ vs 1.34 (0.02) m · s⁻¹, respectively, P < 0.01] and the stroking parameters (i.e., stroke length and stroke index) increased significantly, while the stroke frequency remain unchanged. In D, a stable pace was maintained, while in ND, velocity decreased significantly throughout the 400 m. In D, the performance gains were related to the 400-m D velocity (r=0.78, P < 0.05), and to the body fat mass (BFM, r=0.99, P < 0.01). The stroke index in D was also related to BFM (r=0.78, P < 0.05). Faster and leaner swimmers achieved greater performance gains and stroke index when drafting. Thus, drafting during swimming increases the performance and contributes to the maintenance of stable stroking parameters such as stroke frequency and stroke length during a 400-m swim. Accepted: 10 April 2000     

Electromyographic monitoring of respiratory muscle activity in dyspneic infants and toddlers

The aim of this study was to investigate whether the changes that occurred in the clinical asthma score (CAS) correlated with the changes in the respiratory electromyographic (EMG) activity over the days during admission to hospital in dyspneic infants and toddlers. Sixteen infants and toddlers (9 males) were studied during admission and 7 days after discharge. The CAS was used to assess the severity of dyspnea and consists of five items: respiration rate, wheezing, retractions, observed dyspnea, and inspiration-to-expiration ratio. Each item was scaled 0, 1, or 2, with a maximum score of 10. Electrical activity from the diaphragm (di) and intercostal muscles (int) was derived from surface electrodes. The logarithm of the EMG-Activity-Ratio (log EMGAR; ratio of mean peak-to-bottom EMG activity during admission to the hospital, to that at baseline, 7 days after discharge) was used as EMG parameter. For assessing the association between the repeated observations of the CAS and the EMG measurements we used the quantity r2 obtained with analysis of covariance. On the day of admission the patients had a mean CAS of 5.9 +/- 1.2. On the day of discharge the mean CAS decreased significantly to 2.1 +/- 1.6, indicating that the CAS returned to normal values. In line with this observation, a significant decrease in the log EMGARdi and log EMGARint was observed during the stay in the hospital. Over all subjects the correlation coefficient (r) of log EMGARdi versus CAS was 0.71, log EMGARint versus CAS was 0.67, and the mean log EMGAR versus CAS was 0.75 (p < 0.01, for all values). The correlation coefficients of subjects of < or = 1 year seemed to be lower than those of subjects of > 1 year of age (p < 0.01) and female subjects showed higher correlation coefficients than males. This study showed a moderate, but significant, relationship between the changes that occurred in the CAS and the changes in respiratory EMG activity during admission to hospital in dyspneic infants and toddlers. Moreover, the correlation coefficients of the combined leads of the intercostals and diaphragm (mean log EMGAR) were higher than those of the separate leads. The EMG measurements would extend diagnostic possibilities and would provide an objective measure to evaluate the clinical course of the disease and the efficacy of therapy in infants and toddlers with recurrent wheezing disorders.     

The effect of a high carbohydrate diet on running performance during a 30-km treadmill time trial

Summary The purpose of the present study was to examine the influence of a high carbohydrate diet on running performances during a 30-km treadmill time trial. Eighteen runners (12 men and 6 women) took part in this study and completed a 30-km time trial on a level treadmill without modifying their food intake (trial 1). The runners were then randomly assigned to a control or a carbohydrate (CHO) group. The CHO group supplemented their normal diets with additional carbohydrate in the form of confectionery products during the 7 days before trial 2; the control group matched the increased energy intake of the CHO group by consuming additional fat and protein. The mean (SEM) carbohydrate intake of both groups was 334 (22) g before trial 1, after which the CHO group consumed 566 (29) g · day^–1 for the first 3 days and 452 (26) g · day^–1 for the remaining 4 days of recovery. Although there was no overall difference between the performance times for the two groups during trial 2, the CHO group ran faster during the last 5 km of trial 2 than during trial^–1 [3.64 (0.24) m · s^–1 vs 3.44 (0.26) m · s^–1 P < 0.05] . Furthermore, the 6 men in the CHO group ran the 30 km faster after carbohydrate loading [131.0 (5.4) min vs 127.4 (4.9) min;P < 0.05], whereas there was no such improvement in times of the men in the control group. Blood glucose concentrations of both groups decreased below pre-exercise values during trial^–1 (P < 0.001), but only the control group had a decrease in blood glucose concentrations during trial 2 (P < 0.001). There were no differences between the concentrations of plasma catecholamines of the control group during the two trials. However, the adrenaline concentrations of the CHO group were lower (P < 0.05) during trial 2 than during trial 1, even though they ran faster during trial 2. These results confirm that dietary carbohydrate loading improves endurance performance during prolonged running and that confectionery can be used as an effective means of supplementing the normal carbohydrate intake in preparation for endurance races.     

Effects of preoperative inspiratory muscle training in obese women undergoing open bariatric surgery: respiratory muscle strength, lung volumes, and diaphragmatic excursion

OBJECTIVE:

To determine whether preoperative inspiratory muscle training is able to attenuate the impact of surgical trauma on the respiratory muscle strength, in the lung volumes, and diaphragmatic excursion in obese women undergoing open bariatric surgery.

DESIGN:

Randomized controlled trial.

SETTING:

Meridional Hospital, Cariacica/ES, Brazil.

SUBJECTS:

Thirty-two obese women undergoing elective open bariatric surgery were randomly assigned to receive preoperative inspiratory muscle training (inspiratory muscle training group) or usual care (control group).

MAIN MEASURES:

Respiratory muscle strength (maximal static respiratory pressure – maximal inspiratory pressure and maximal expiratory pressure), lung volumes, and diaphragmatic excursion.

RESULTS:

After training, there was a significant increase only in the maximal inspiratory pressure in the inspiratory muscle training group. The maximal expiratory pressure, the lung volumes and the diaphragmatic excursion did not show any significant change with training. In the postoperative period there was a significant decrease in maximal inspiratory pressure in both the groups. However, there was a decrease of 28% in the inspiratory muscle training group, whereas it was 47% in the control group. The decrease in maximal expiratory pressure and in lung volumes in the postoperative period was similar between the groups. There was a significant reduction in the measures of diaphragmatic excursion in both the groups.

CONCLUSION:

The preoperative inspiratory muscle training increased the inspiratory muscle strength (maximal inspiratory pressure) and attenuated the negative postoperative effects of open bariatric surgery in obese women for this variable, though not influencing the lung volumes and the diaphragmatic excursion.     

The effect of ambient temperature on gross-efficiency in cycling

Time-trial performance deteriorates in the heat. This might potentially be the result of a temperature-induced decrease in gross-efficiency (GE). The effect of high ambient temperature on GE during cycling will be studied, with the intent of determining if a heat-induced change in GE could account for the performance decrements in time trial exercise found in literature. Ten well-trained male cyclists performed 20-min cycle ergometer exercise at 60% (power output at which VO_2max was attained) in a thermo-neutral climate (N) of 15.6 ± 0.3°C, 20.0 ± 10.3% RH and a hot climate (H) of 35.5 ± 0.5°C, 15.5 ± 3.2% RH. GE was calculated based on VO₂ and RER. Skin temperature (T _sk), rectal temperature (T _re) and muscle temperature (T _m) (only in H) were measured. GE was 0.9% lower in H compared to N (19.6 ± 1.1% vs. 20.5 ± 1.4%) (P < 0.05). T _sk (33.4 ± 0.6°C vs. 27.7 ± 0.7°C) and T _re (37.4 ± 0.6°C vs. 37.0 ± 0.6°C) were significantly higher in H. T _m was 38.7 ± 1.1°C in H. GE was lower in heat. T _m was not high enough to make mitochondrial leakage a likely explanation for the observed reduced GE. Neither was the increased T _re. Increased skin blood flow might have had a stealing effect on muscular blood flow, and thus impacted GE. Cycling model simulations showed, that the decrease in GE could account for half of the performance decrement. GE decreased in heat to a degree that could explain at least part of the well-established performance decrements in the heat.     

Effect of exercise on metabolism of glycogen and triglycerides in the respiratory muscles

It was shown that during muscular exertion the diaphragm muscle and the intercostal muscles utilize endogenous glycogen whereas only the diaphragm muscle utilizes endogenous triglycerides. The post-excercise glycogen repletion in the diaphragm muscle was much faster than in the intercostal muscles. In the diaphragm muscle, marked overshoot of the glycogen level occurred early after the exercise.The work was supported by Polish Academy of Sciences within the project 10.4.2.01.3.2.     

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.     

Revisiting the effect of posture on high-intensity constant-load cycling performance in men and women

It was recently observed that inclining the body from a supine to upright position improved the performance of high-intensity, constant-load cycling to a larger extent in men than women (Egaña et al. in Eur J Appl Physiol 96:1–9, 2006), although this gender-related effect was based on a small number of men (n  =  5) and women (n  =  5). To explore this effect further, we studied the effect of body tilt on cycling performance in a larger and different group of men (n  =  8) and women (n  =  18). Peak power, peak \({{\dot{V}}\hbox{O}_{2}}\) and the ventilatory threshold (VT) were determined during an upright maximal graded cycle test, and a high-intensity test (80% peak power) was performed to failure in both the upright and supine positions. Performance was significantly longer in the upright compared with supine position in men (17.4 ± 7.7 vs. 7.6 ± 3.4 min) and women (14.1 ± 6.0 vs. 6.0 ± 3.7 min). The magnitude of this postural effect was not significantly different between men and women; whereas it was significantly correlated with the relative intensity of exercise expressed as a function of VT (r  =  ?0.39). These data demonstrate that the postural effect on high-intensity cycling performance is not influenced by gender; but that it is related to the intensity of exercise relative to the ventilatory threshold.     

Myelinated nerve fiber supply and muscle spindles in the respiratory muscles of cat: Quantitative study

Summary The present study was undertaken to provide quantitative data on the myelinated fibers of the phrenic and intercostal nerves and the number of spindles in the main respiratory muscles of the cat.The myelinated component of the phrenic and intercostal nerves was studied in the cat. Histograms of sequency distributions as a function of nerve fiber diameter were established for normal nerves. Certain nerves were then examined 35 to 40 days after excision of the dorsal spinal ganglia. The muscle spindles of the corresponding muscles were counted and localized, and, on the basis of several morphological criteria, were classified with those usually described in the interosseous muscles.The study of the nerves, as that of the spindles, demonstrates clear differences of proprioceptive innervation among the respiratory muscles. The lateral part of the diaphragm and the Triangularis sterni have practically no spindles. The external muscles of the first thoracic spaces are very rich in spindles. Respiratory muscles can be ranged in an almost continuous manner between these two extremes.