Biomedical subjects

Nicolas Tordi

Publications and source records attributed to Nicolas Tordi.

11 recordsLinked to original sources

PubMed2006

Effects of resuming endurance training on arterial stiffness and nitric oxide production during exercise in elite cyclists.

Exercise training improves arterial compliance due to increases in blood flow to skeletal muscle during repeated bouts of daily exercise. The effect of resuming training on arterial stiffness in previously well-trained subjects is poorly documented. Hence, the purpose of this study was to determine the vascular effects induced by return to exercise in highly trained cyclists. Pulse wave velocity (PWV), an index of arterial stiffness, was assessed at rest and during constant moderate-intensity cycle exercises before and after 16 weeks of endurance training. The impact of daily exercise on the concentration of nitric oxide (NO) measured as nitrate in plasma was examined at rest and during maximal exercise before and after the training period. At rest, PWV was significantly lower in the subjects after a training session (6.4 +/- 0.4 vs. 8.1 +/- 0.4 m x s(-1), p < 0.05). During constant exercise, PWV was significantly and positively correlated with increases in blood pressure. The increased PWV induced by exercise was, however, significantly lower after training (9.8 +/- 0.6 vs. 11.4 +/- 0.6 m x s(-1), p < 0.05). After the training program, nitrate plasma levels at rest were higher. During the maximal test, the plasma nitrate concentration was increased in the subjects studied before the training period, but not after. These results show that resumption of chronic endurance training rapidly induces adaptive changes in arterial stiffness and NO release that may contribute to improved physical fitness in athletes.

Adult↗

PubMed2006

Is the VO2 slow component in heavy arm-cranking exercise associated with recruitment of type II muscle fibers as assessed by an increase in surface EMG?

The recruitment of additional type II muscle fibers is one mechanism often suggested to be responsible for the slow component of oxygen uptake (VO2 (SC)). We hypothesized that surface electromyogram (EMG) of the biceps brachii, triceps brachii, anterior deltoid, and infraspinatus muscles could be related to the VO2 (SC) amplitude during arm-cranking exercises above ventilatory threshold (VT). Eight healthy subjects performed transitions from rest to 6-min heavy exercise at a constant power output of approximately 40% between VT and peak VO2. A 2-component exponential model was used to fit the VO2 response. EMG were recorded the last 15 s of each minute to obtain root mean square (RMS) and mean power frequency (MPF). Mean EMG responses for RMS and MPF were calculated by averaging EMG responses of the 4 muscles. The VO2 (SC) amplitude was of 530 +/- 166 mL/min and occurred after 134 +/- 31 s of exercise onset. Significant correlations were found for most of the subjects between EMG parameters and the VO2 SC amplitude as determined between the 2nd and the 6th minute. For all muscles, RMS values significantly increased over time during the VO2 (SC), whereas MPF decreased significantly. These results suggest a relation between the recruitment of additional type II muscle fibers and the VO2 (SC) in arm-cranking exercises.

Adult↗

PubMed2005

Ventilation efficiency and pulmonary function after a wheelchair interval-training program in subjects with recent spinal cord injury.

OBJECTIVE: To study the effect of a wheelchair interval-training program on the ventilatory function of subjects with recent spinal cord injury (SCI). DESIGN: Evaluation trial before and after a training program. SETTING: Center of reeducation and university hospital. PARTICIPANTS: Six subjects (5 men, 1 woman) hospitalized after a recent SCI. INTERVENTION: On a wheelchair ergometer, subjects with SCI performed 30 minutes of interval training 3 times a week for 6 weeks. The training program was part of their reeducation program. MAIN OUTCOME MEASURES: Spirometric values at rest and dynamic ventilatory responses were studied before and after this training program with a spirometric test, a maximal exercise test that increased by 5W every 2 minutes, and a submaximal test. RESULTS: Spirometric values at rest did not change after training. At maximal exercise, peak ventilation (Vepeak, 7.5%), peak breathing frequency (f peak) (-13.4%), peak tidal volume (Vtpeak +28.9%), and the ventilatory reserve (12.9%) improved after training. The oxygen cost of Ve decreased significantly (-20%) after training. We observed for the wheelchair tests that, at the same workload after training, Ve and f decreased and Vt increased. CONCLUSIONS: After 6 weeks of our interval-training program in subjects with recent SCI, the increase of Vt and the decrease of oxygen cost of Ve indicated better ventilatory efficiency.

Ergometry↗

PubMed2005

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.

Adult↗

PubMed2004

Short- and long-term effects of a single bout of exercise on heart rate variability: comparison between constant and interval training exercises.

Heart rate variability (HRV) was assessed during the short- (within 1 h) and long- (within 48 h) term recovery following a single bout of either constant (CST) or interval training (SWEET) exercise performed at the same total physical work [9.4 (0.3) kJ kg(-1)]. R-R intervals, systolic (SAP) and diastolic (DAP) arterial pressures were recorded in supine and upright positions before and 1, 24 and 48 h after the termination of the exercises in ten male subjects [mean (SEM), age 24.6 (0.6) years, height 177.2 (1.1) cm and body mass 68.5 (0.9) kg]. The parameters were also recorded in the supine position during the first 20 min following the end of the exercise. Spectral analysis parameters of HRV [total (TP), low- (LF), and high- (HF) frequency power, and LF/TP, HF/TP and LF/HF ratios] were determined over 5 min during each phase. Except for higher HF values in both supine and upright positions during the first hour following CST compared with SWEET, cardiovascular and HRV analysis responses were of the same magnitude after their termination. R-R intervals, TP, and HF/TP were significantly decreased while LF/TP and LF/HF were significantly increased during the early recovery, when compared with control values. This could be a response to the significant decrease in SAP and DAP at this time. Twenty-four and 48 h after the end of the exercise, HRV parameters were at the same levels as before exercises in the supine posture, but a persistent tachycardia continued to be observed in the upright posture, together with reduced TP values, showing that cardiovascular functions were still disturbed. The short-term HRV recovery seemed dependent on the type of exercise, contrary to the long-term recovery.

Adult↗

PubMed2004

Mechanical efficiency during hand-rim wheelchair propulsion: effects of base-line subtraction and power output.

OBJECTIVE: The purpose of this study was to compare four methods of calculating the mechanical efficiency of hand-rim wheelchair propulsion. METHODS: After completing a maximal incremental test, 18 untrained able-bodied males (mean age 22 years) performed four 4-min bouts of exercise (0%, 40%, 55%, and 70% of peak power output) on a wheelchair-ergometer. The mechanical efficiency was calculated during each submaximal bout by the ratio of work accomplished to the amount of energy expended with four indices: gross (no base-line correction), net (resting metabolism as base-line correction), work (unloaded movement as base-line correction) and delta (measurable work as base-line correction) indices. RESULTS: Work efficiency (16.8-13.8%) were significantly higher (P < 0.001) than gross (6.5-8.9%) or net efficiency (9.9-11.1%) at 40-70% peak power output, respectively. Net efficiency was also significantly lower than work efficiency (P < 0.001) at all intensity. Moreover, gross and work efficiency increased and decreases (P < 0.001) respectively with intensity. In contrast, net and delta efficiency remained unchanged. CONCLUSIONS: Depending upon the base-line used, each efficiency index provided different values and were differently affected by the exercise intensity. Precautions should be taken on the conclusions about the mechanical efficiency of hand-rim wheelchair propulsion. Moreover, comparisons between the four efficiency indices among themselves allowed a better and complete description of wheelchair locomotion and wheelchair dependent person. Gross or net efficiencies better reflected the actual mechanical efficiency of the hand-rim wheelchair propulsion whereas work or delta efficiencies investigated the efficiency of muscular contraction during this movement. RELEVANCE: Since the four mechanical efficiency indices measured different aspects of performance, it will have consequences when it comes to choosing an appropriate index. The better understanding of mechanical efficiency index may help future investigators to choose the most appropriate index for their purposes.

Adult↗

PubMed2004

A specific arm-interval exercise program could improve the health status and walking ability of elderly patients after total hip arthroplasty: a pilot study.

OBJECTIVE: To investigate the influence of an arm-interval exercise program for the upper limbs on health status and walking ability in elderly patients after total hip arthroplasty. DESIGN: A randomized controlled investigation. After surgery, a control group started a general rehabilitation program, and a training group combined it with an arm-interval exercise program. SUBJECTS: Fourteen patients (age 75.1 +/- 4.8 years) were randomly assigned to the control group (n = 7) and the training group (n = 7). METHODS: A Western Ontario and MacMaster University (WOMAC) Osteoarthritis Index was completed and an incremental exercise test on an arm crank ergometer was also performed 1 month before (T(-1)) and 2 months after surgery (T2). Moreover, a 6-minute walk test was performed at T2. RESULTS: Both groups significantly improved all dimensions of WOMAC, except in WOMAC physical function subscale in the control group. The training group covered a significantly longer distance in the walking test than the control group and also presented significantly higher VO2 peak value at T2. Correlation analyses indicate that VO2 peak value and the distance covered in the 6-minute walking test were significantly associated with functional status. After calculating the ratio distance covered/score at WOMAC physical function, we observed a significantly higher ratio value in the training group than in the control group. CONCLUSION: Preliminary results indicate that the improvement in physical fitness and functional status of the training group seems to be associated with better health status.

Aged↗

PubMed2004

Perceived exertion and rehabilitation with arm crank in elderly patients after total hip arthroplasty: a preliminary study.

This preliminary study examined, in a restricted randomized trial, the effects of a 6-week arm-crank rehabilitation training program in elderly osteoarthrosis patients after total hip arthroplasty, first on physiological and perceptual responses and second on physical function. Two groups of patients were studied: a training group (N = 7, mean age = 74.9 yr, standard deviation [SD] = 5.0 yr) who followed a training program in addition to traditional rehabilitation, and a control group who followed traditional rehabilitation only (N = 7 mean age = 75.4 yr, SD = 5.1 yr). At the beginning of the training program, the heart rate and the perceived exertion were not significantly correlated during the exercise session. However, at the end of the training program, five patients had a significant heart rate/perceived exertion relationship (p < 0.05). Furthermore, positive effects of the arm-crank rehabilitation training program were observed on cardioventilatory and functional responses in the training group compared with the control group. These results suggest that after an habituation period, most of our elderly osteoarthrosis patients experienced physical sensations that were connected to physiological responses. Therefore, perceived exertion could be useful in these patients to regulate exercise intensity, especially at the end of and after the rehabilitation period.

Aged↗

PubMed2003

Force-velocity characteristics of upper limb extension during maximal wheelchair sprinting performed by healthy able-bodied females.

The aim of this study was to determine the relationship between force and velocity parameters during a specific multi-articular upper limb movement--namely, hand rim propulsion on a wheelchair ergometer. Seventeen healthy able-bodied females performed nine maximal sprints of 8 s duration with friction torques varying from 0 to 4 N x m. The wheelchair ergometer system allows measurement of forces exerted on the wheels and linear velocity of the wheel at 100 Hz. These data were averaged for the duration of each arm cycle. Peak force and the corresponding maximal velocity were determined during three consecutive arm cycles for each sprint condition. Individual force-velocity relationships were established for peak force and velocity using data for the nine sprints. In line with the results of previous studies on leg cycling or arm cranking, the force-velocity relationship was linear in all participants (r = -0.798 to -0.983, P < 0.01). The maximal power output (mean 1.28 W x kg(-1)) and the corresponding optimal velocity (1.49 m x s(-1)) and optimal force (52.3 N) calculated from the individual force-velocity regression were comparable with values reported in the literature during 20 or 30 s wheelchair sprints, but lower than those obtained during maximal arm cranking. A positive linear relationship (r = 0.678, P < 0.01) was found between maximal power and optimal velocity. Our findings suggest that although absolute values of force, velocity and power depend on the type of movement, the force-velocity relationship obtained in multi-articular limb action is similar to that obtained in wheelchair locomotion, cycling and arm cranking.

Acceleration↗

PubMed2003

Recovery after total hip joint arthroplasty in elderly patients with osteoarthritis: positive effect of upper limb interval-training.

OBJECTIVE: To evaluate the influence of an interval training program for the upper limbs on cardiorespiratory fitness and walking ability in elderly patients after total hip joint arthroplasty. DESIGN: A randomized controlled trial. After surgery, control and training groups started general rehabilitation. Training group combined it with an arm-interval exercise program (3 sessions of 30 minutes per week, for 6 weeks). SUBJECTS: Patients were assigned randomly to control (n = 7) and training groups (n = 7). METHODS: Incremental exercise tests were carried out until exhaustion on an arm crank ergometer 1 month before and 2 months after surgery. A 6-minute walk test was also performed 2 months after surgery. RESULTS: VO2 peak increased significantly in the training group (p = 0.0424) and did not change in the control group. The difference in VO2 peak change between the groups was significant (p = 0.0362, +19.2% in the training group and -3.5% in the control group). In the walking test the training group covered a significantly longer distance than did the control group (p = 0.0055, 396.4 metres and 268.1 metres, respectively). CONCLUSION: These results stress the importance of physical training in a rehabilitation program after total hip joint arthroplasty and this should be considered for improving the current practices in rehabilitation.

Aged↗

PubMedDate not supplied

Influence of a 6-week arm exercise program on walking ability and health status after hip arthroplasty: a 1-year follow-up pilot study.

The influence of an upper-limb interval-training program after total hip arthroplasty (THA) in elderly patients was studied during a 1 yr follow-up on health status and walking ability. After surgery, 14 patients were randomly assigned to the control group that started a 6 wk general rehabilitation program or the training group that combined it with an interval exercise program on an arm ergometer. A Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index was completed 1 mo before and 2 mo and 1 yr after surgery. A 6 min walking test was performed at 2 mo and 1 yr after surgery. The training group covered a significantly longer distance than the control group in the 6 min walk test and obtained significantly lower WOMAC scores both at 2 mo and 1 yr after surgery. However, both groups significantly improved in WOMAC and in their performance during the survey. Endurance-type upper-body aerobic training in a rehabilitation program might be important after THA.

Aged↗