[Blood lactate three minutes after a graded exercise test: a criterion of maximal exercise in patients with COPD]. / Lactatémie trois minutes après une EFX : un critère de maximalité chez le patient BPCO.

INTRODUCTION: The graded exercise test (GXT) is used to measure the exercise capacity of patients with chronic obstructive pulmonary disease (COPD). To do this GXT must be maximal (exhaustive). However, the value of the blood lactate at the GXT endpoint [La(-)max] or after a recovery period of three minutes [La(-)recovery], to confirm that the GXT is maximal, remains controversial. The purpose of the present study is to determine a threshold of [La(-)max] and/or [La(-)recovery], which confirms the exhaustiveness of GXT in patients with COPD. METHODS: Thirty-six patients with COPD performed a GXT until exhaustion on a cycle ergometer. During the GXT cardiorespiratory parameters, [La(-)max] and [La(-)recovery] were measured. When at least three out of five of the most frequently used criteria to confirm exhaustion were met, GXT was considered as maximal. Conversely, GXT was considered as sub-maximal when less three criteria were observed. The receiver operating characteristic (ROC) curves were analyzed. RESULTS: For [La(-)max] the areas under the ROC curve and the areas under the diagonal were not significantly different (P=0.16). For [La(-)recovery] the ROC curve inflected itself at 5.8mmol/L (sensitivity=0.92 and specificity=0.56). CONCLUSIONS: It was not possible to use [La(-)max] to confirm exhaustion in our population. However, [La(-)recovery]<5.8mmol/L may help to confirm non-exhaustion during GXT in patients with COPD. Below this blood lactate threshold 93% patients performed a sub-maximal GXT.

Relevance of the measure of perceived exertion for the rehabilitation of obese patients.

The most common tool used for measuring effort perception is the rating scale of perceived exertion (RPE) developed by Borg. This scale is also used for various outcomes in the general population. The validity and reliability of this scale have already been reported in obese patients. However, the relevance of measuring perceived exertion in obese patients is still poorly known. This review of the literature presents the Borg RPE scale (i.e., validity, reliability and recommendations) and its main advantages during graded exercise tests (e.g., comparison of physical capacity, predicting physiological variables, verifying exhaustion and exercise safety) and rehabilitation programs (e.g., individualized exercise intensity, evaluation of the impact of a rehabilitation program and even determining the perceptual preference) in obese patients. This review of the literature underlines the relevance and usefulness of the Borg RPE scale, which is still underused in obese patients. However, additional studies are still necessary before using this scale routinely in all obese patients (regardless of the severity of their obesity or associated complications).

Dynamic cardiorespiratory changes in obese women.

AIM: This study examined the effects of an exercise training program on ventilatory function at rest and the exercise cardiorespiratory pattern in relation to body composition in obese individuals (53.4±7.6 years; 158.6±6.7 cm). METHODS: After initial tests (exercise testing and anthropometric assessment), ten women participated in a 12-week training program combining strength exercise and aerobic exercise at the ventilatory threshold, three times per week for 90 minutes. RESULTS: The post-training mean ventilatory efficiency (ΔE/ΔCO(2)) and cardiac efficiency (ΔHR/ΔO(2)) were improved (P<0.05, respectively). Decreased fat mass (-1.2 kg, P<0.01), increased lean body mass (+1 kg, P<0.01), and decreased waist and hip circumferences (-5.5 cm and -5 cm, respectively, P<0.05) were also obtained after training. CONCLUSION: The program significantly improved a number of physiological variables in our obese patients, although not to sedentary healthy levels. The results show that a functional exercise program has the potential to improve physiological variables and dynamic cardiorespiratory response to exercise in obese women.

Quality of life and obesity class relationships.

The aim of this study was to quantify the impact of obesity class on Health-Related Quality Of Life (HRQOL) and Total daily Energy Expenditure (TEE). 69 obese individuals were self-selected to 1 of 3 groups based upon Body Mass Index (BMI). Anthropometric parameters (height, weight, waist and hip circumference, fat mass, lean body mass), biological parameters (high density lipoprotein, low density lipoprotein, triglycerides, glycaemia, total cholesterol), and resting energy expenditure were assessed for each group. The Short Form Health Survey (SF-36) questionnaire and Hospital Anxiety Depression (HAD) scale were used to measure HRQOL, and TEE was estimated by Kurpad's method. Class 3 obesity was associated with greater impairment of the physical aspects of the SF-36 (37.2±11.3), greater depression risk (8.2±4.1), and higher TEE (30.0±7.9 Kcal·day (-1)·kg (-1)) than the lower obesity classes. No difference was observed among the 3 groups in the mental and psychosocial aspects of HRQOL. Impaired physical functioning was correlated with fat mass, age, waist circumference, glycaemia control and bodily pain. TEE was positively correlated with BMI, weight, fat mass and lean body mass. The obesity class had a negative impact on the physical health aspect of HRQOL, depression risk and energy expenditure. These impairments were associated with excess fat mass, waist circumference and glycaemia parameters.

Effect of force symmetry on coordination in crawl.

The relationship between breathing laterality and motor coordination symmetry as a function of the symmetry of medial rotator muscle force in the shoulders was investigated. The principal objective was to distinguish swimmer profiles. Thirteen expert male swimmers performed the front crawl and were assessed for: (i) inter-arm coordination with the IdC and arm coordination symmetry with the Symmetry Index, (ii) breathing laterality, and (iii) the symmetry of the isokinetic force in the shoulder medial rotators. The results indicated that the relative duration of catch+pull was greater for the dominant arm (51.7%) than for the non-dominant arm (48.4%) for the swimmers with force asymmetry (p<0.05) and occurred on the side with the higher force (dominant arm). Two profiles were revealed: (i) swimmers for whom breathing laterality was related to force symmetry and stroke phase duration and (ii) swimmers for whom the impact of breathing laterality on force symmetry and stroke duration was low. The first profile corresponded to sprint specialists and the second profile corresponded more to middle-distance specialists.

A new portable device for assessing locomotor performance.

We investigated the validity of a new portable system and the feasibility of the method for gait analysis as the assessment of gait has clinical relevance in the study of locomotor pathologies. This system is composed of a data logger, triaxial accelerometers, and software. Measurements of the pelvis kinematics during gait were performed on five hip osteoarthritic subjects and 15 healthy subjects using the portable system and a reference system (Vicon). The healthy subjects were studied in conditions of normal gait and gait altered by a heelpiece. The studied variables were the vertical amplitude of the sacrum, the time of gait cycle and the vertical trajectories of the spines. The new system corresponded with the reference system for the studied variables. The small differences between the two systems in the vertical amplitude of the sacrum (0.53 +/- 6.39 mm), time of the gait cycle (0.002 +/- 0.05 s), and the vertical trajectories of the spine (coefficient correlation of 0.06 +/- 0.05) confirmed the validity of the portable system data. The results showed a distortion of the pelvis trajectory when the gait was impaired. The portable system provides an objective method to discriminate normal from limping gait and is easy to use outside of the laboratory.

Comparison of the decrease in strength between hamstrings and quadriceps during isokinetic fatigue testing in semiprofessional soccer players.

An imbalance in the agonist/antagonist ratio has been identified as a pathologic factor. Using an isokinetic dynamometer, several studies have investigated the loss of quadriceps strength due to fatigue, but few have explored this phenomenon in the hamstrings. This study assessed the decline in strength of the hamstring and quadriceps muscles with fatigue. The goal was to determine whether a divergence in the decline in strength occurs that would affect the hamstring to quadriceps ratio of endurance. Twenty-seven professional soccer players were selected for endurance testing to evaluate fatigue on an isokinetic dynamometer. The decline in hamstring strength was significantly greater than that of the quadriceps after 15 repetitions for the dominant leg and after 40 repetitions for the nondominant leg. This study also revealed a decline in the endurance ratio compared with the maximal strength ratio in the dominant leg after 30 repetitions. In fatigue states, the decline in hamstring strength diverges from that of the quadriceps in both legs. This difference in resistance to fatigue provokes an imbalance that may affect the stabilizing function of the thigh muscles. These results can be considered as indicators of an increased risk of injury during exhausting effort.

Intra-cyclic distance per stroke phase, velocity fluctuations and acceleration time ratio of a breaststroker's hip: a comparison between elite and nonelite swimmers at different race paces.

The aim of this study was to compare the intra-cyclic velocity graphs of breaststroke swimmers at two skill levels in relation to their movement phases. Two groups of nine male swimmers were videotaped underwater at three swimming race paces corresponding to their actual competitive times for the 200-m, 100-m and 50-m breaststroke. Their forward intra-cyclic hip velocity was recorded with a velocity-meter. The breaststroke cycle was divided into four phases: leg propulsion, leg-arm lag phase, arm propulsion, and arm and leg recovery. From the velocity-time data, the following parameters were computed: an index of velocity fluctuations (IVF), the distance covered during each stroke phase, and an acceleration-deceleration time ratio (ADTR). The main results showed that in both groups of swimmers, when the race pace increased, the distance covered during the leg-arm lag phase decreased, while the other swimming phases remained stable. When expressed in relative values, the percentage of distance covered during the leg-arm lag phase decreased. In nonelite swimmers, the percentage of distance covered in the other stroke phases increased significantly, while only a tendency was noted in the elite group. Elite swimmers demonstrated a higher ADTR at the 50-m pace than at their 100-m and 200-m paces. An inter-group comparison showed that elite swimmers had higher values for the IVF and ADTR, which indicated their capacity to accelerate to boost the swim and highlighted the relevancy of these factors to discriminate skill level.

Physiological responses to repeated apneas in underwater hockey players and controls.

The aim of this study was to investigate the effects of short repeated apneas on breathing pattern and circulatory response in trained (underwater hockey players: UHP) and untrained (controls: CTL) subjects. The subjects performed five apneas (A1-A5) while cycling with the face immersed in thermoneutral water. Respiratory parameters were recorded 1 minute before and after each apnea and venous blood samples were collected before each apnea and at 0, 2, 5 and 10 minutes after the last apnea. Arterial saturation (SaO2) and heart rate were continuously recorded during the experiment. Before the repeated apneas, UHP had lower ventilation, higher P(ET)CO2 (p < 0.05) and lower P(ET)O2 than CTL (p < 0.001). After the apneas, the P(ET)O2 values were always lower in UHP (p < 0.001) than CTL but with no difference for averaged P(ET)CO2 (p = 0.32). The apnea response, i.e., bradycardia and increased mean arterial blood pressure, was observed and it remained unchanged throughout the series in the two groups. The SaO, decreased in both groups during each apnea but the post-exercise SaO2 values were higher in UHP after A2 to A5 than in CTL (p < 0.01). The post-apnea lactate concentrations were lower in UHP than in CTL. These results indicate that more pronounced bradycardia could lead to less oxygen desaturation during repeated apneas in UHP. The UHP show a specific hypoventilatory pattern after repeated apneas, as well as a more pronounced cardiovascular response than CTL. They indeed showed no detraining of the diving response.

Articular cartilage, degenerative process, and repair: current progress.

The aim of this paper is to review the current knowledge about degenerative and repair process of articular cartilage, and relationship between osteoarthritis and physical activities. Data Pubmed, ScienceDirect data base are interrogated for the period 1994 - 2003. Key words are: cartilage, osteoarthritis, exercise, rehabilitation. The mechanical biology of the cartilage and the chondrocytes, the effects of physical activity on the cartilage, the main studies on clinical trials on rehabilitation are reviewed. Chondrocyte and cartilage structure and function change with mechanical stresses. Mechanical loads can modulate cartilage matrix turnover. Joint injury increases the risk of osteoarthritis, and sports that subjects joints to repetitive high levels of impact loading increase the risk of injury and degeneration. In human, intensive physical exercises seem associated with osteoarthritis development. None of the current procedures for repairing articular cartilage restores a normal articular zone, however, selected procedures can predictably benefit selected subjects. This article presents the biology and discusses the alteration of cartilage as well as the osteoarthritis process which is not yet well understood. Current medical approaches to the treatment of osteoarthritis also are presented. Rehabilitation programme could be beneficial in the therapeutic management of osteoarthritis.

Pulmonary function in children after a single scuba dive.

This study evaluated the respiratory effects of a single dive in children. Eighteen young divers and 18 controls participated in our study (age range: 9 - 13 years). Volumes and expiratory flow rates were measured 20 minutes before and 10 minutes after one air dive (3 meters, 25 minutes). Before the dive, no differences were noted regarding pulmonary parameters. Ten minutes after the dive, decreases were noted in forced expiratory volume in 1 s (FEV1) and maximal voluntary ventilation (- 8 %, - 5.3 %, respectively; p < 0.01), peak expiratory flow, maximal expiratory flow rates at 50 % of FVC (MEF(50 %)) and MEF(25 %), forced mid-expiratory flow rate (FEF(25 - 75 %)), and FEV1/FVC(- 5.9 %, - 14.3 %, - 21.4 %, - 4.2 %, - 3.5 %, respectively; p < 0.05). The respiratory pattern observed 10 minutes after a single dive to three meters indicated airway narrowing. However, no association between diving experience and lung function was obtained.

Ventilatory function in experienced recreational scuba divers: Evidence of small airways disease?

Diving has shown long-term effects on respiratory function in trained professional divers, indicating the development of small airways disease. The results are more controversial in trained recreational divers because of the different degrees of exposure and training. The aim of this study was to investigate the effects of recreational diving on respiratory function in highly experienced divers. Volumes and expiratory flow rates were measured in 32 older recreational divers (51.6 +/- 7.4 years). The forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were higher (+ 4.9 % and + 6 %, respectively; p < 0.01) than the theoretical standards (ERS 93). These values tended to decrease more rapidly as the age advanced (age range: 43 - 73 years) (p < 0.05). Moreover, the mid-expiratory flows at 50 %, 25 % and 25 - 75 % of vital capacity (MEF(50 %), MEF(25 %) and MEF(25 - 75 %)) were significantly decreased. These early signs of decrease suggest slight small airways disease in older experienced recreational divers.

Hip passive range of motion and frequency of radiographic hip osteoarthritis in former elite handball players.

OBJECTIVE: To establish the relation between handball playing, passive hip range of motion (ROM), and the development of radiological hip osteoarthritis (OA) in former elite handball players. Two related issues are addressed: (a) the relation between long term elite handball playing and the incidence of hip OA; (b) the relations between hip ROM, OA, and pain. METHODS: Data on 20 former elite handball players and 39 control subjects were collected. A questionnaire yielded personal details, loading patterns during physical activity, and previous lower limb joint injury. Bilateral radiographs were analysed to diagnose and classify hip OA. Passive hip ROM was measured bilaterally with a goniometer. RESULTS: A close relation was found between long term elite handball practice and the incidence of hip OA: 60% of the handball players were diagnosed with OA in at least one of the hip joints compared with 13% of the control subjects. Passive ROM measured in the handball players was significantly lower for hip flexion and medial rotation and higher for abduction, extension, and lateral rotation than the control values. The handball players with OA reported less pain in the hip joints during daily activities than the control subjects with OA. CONCLUSION: The risk of developing premature hip OA seems high for retired handball players and significantly greater than for the general population. Pain and discomfort represent two difficult diagnostic challenges to the sports physician, as the repetitive nature of movements that are specific to handball can lead to alterations that are rarely seen in the general population.

Arterial oxygen saturation and heart rate variation during breath-holding: comparison between breath-hold divers and controls.

Breath-holding induces cardiovascular responses, notably bradycardia and peripheral vasoconstriction, which are known collectively as the diving response. This response is oxygen-conserving, i.e. an augmented response attenuates arterial oxygen desaturation, and is enhanced by apnoea training. To test this hypothesis, we compared heart rate (HR) and arterial oxygen saturation (SaO (2)) in breath-hold divers (BHD) and non-divers (ND). Nine BHD and nine healthy ND performed two static apnoeas (for 30 s and 45 s) and two dynamic apnoeas (for 30 s and 45 s) while swimming underwater at 0.7 m . s (-1). The pool temperature was 26 degrees C. The apnoeas were performed at 60 % of forced vital capacity. Heart rate (HR) and SaO (2) were recorded before breath-holding and at its end and are expressed in % change from rest values (DeltaHR and DeltaSaO (2)). Comparisons between BHD and ND showed that DeltaSaO (2) were lower in divers after both static apnoeas for 30 s and 45 s (- 2.8 % vs. - 5.5 %; - 3.2 % vs. 6.3 %; p < 0.05, respectively) and dynamic apnoeas (- 6 % vs. - 10.1 %; - 7.2 % vs. - 12.3 %; p < 0.05, respectively). The change in HR did not differ between the two groups and negative linear relations were found between DeltaHR and DeltaSaO (2) in both divers and ND (r = 0.66 and 0.61, respectively; p < 0.001). Moreover, the slope was lower for the divers (- 0.785 vs. - 0.1429; p < 0.001). Our results suggest that apnoea training explained the greater oxygen conservation seen in the divers in both static and dynamic conditions.

[Ventilatory adaptations for breath holding in divers]. / Adaptations respiratoires chez le plongeur en apnée.

The length of breath-hold duration in divers is dependant on a number of interacting variables which include mechanical factors (lung volumes), chemical factors (sensitivity to hypoxia and hypercapnia), non-chemical factors (involuntary muscular contractions), psychological factors (motivation, stress, competition) and various extrinsic factors (training, muscular exercise). These stimulus provoke the unpleasant sensation of an urge to breathe at the termination point of the breath hold. Training and experience produces adaptations in divers which decreases sensitivity to CO(2) and which delays and minimises the involuntary contractions of respiratory muscles provoked by the absence of respiratory movements. These adaptations modify the breaking point of, and increase the duration of breath holding. Godfrey & Campbell's model (1968), modified by Courteix et coll. (1993) and Delapille (2000), attempts to explain the control of breathing in the context of apnea and to define the effects of each of these stimulus on the respiratory activity of divers and non-divers.

Kinematic analysis of butterfly turns of international and national swimmers.

The aims of this study were (1) to evaluate the different turn phases of 200 m butterfly during competition in a 50 m pool, (2) to determine if wall contact times are related to swim speed and (3) to compare the turn variables of a European Champion with other swimmers. In the first part of the study, we assessed the turns of 22 swimmers ranked in three groups according to 200 m butterfly swim performance (fast group = 121.73+/-3.03 s, intermediate group = 126.25+/-0.55 s, slow group = 129.24+/-2.30 s). Two turn times were recorded: the first before the turn (i.e. the time it takes the swimmer's head to reach the wall from 7.5 m away) and the second after the turn (i.e. the time from the wall to the point at which the swimmer's head passes 7.5 m away). The third turn was performed significantly faster by the fast group than by the slow group, both before (P< 0.01) and after (P< 0.02) the turn. In the second part of the study, objectives (2) and (3) were evaluated among 15 swimmers based on a specific protocol. Three cameras (50 Hz) simultaneously recorded the turn; these were placed above the water 10 m before the wall, 5 m before and just above the wall. Longer contact times of the feet on the wall were associated with a faster push-off speed (P < 0. 02). The European Champion achieved an improved contact time while performing a rapid pull-out speed.

Heart rate variation after breath hold diving with different underwater swimming velocities.

BACKGROUND: The aim of this study was to demonstrate the kinetics of heart rate and blood lactate level obtained after repeated short breath holds with muscular effort in a swimming pool. EXPERIMENTAL DESIGN: each subject had to perform a series of breath hold diving at rest and three series for different underwater swimming velocities. A series corresponded to six dives of a 30 sec duration separated by a recovery period of 30 sec. Heart rates and blood lactate levels were measured at rest and at the end of each series of breath holds. PARTICIPANTS: the population was composed of 10 male subjects divided into one trained group (5 experts) and one group of 5 beginners. RESULTS: Results indicated a higher bradycardia for the expert group at static breath hold (54.25 vs 65.5 beats x min-1). At the end of a series of breath holds, tachycardia was higher for beginners at different underwater swimming velocities. These values were less significant than the heart rate measured in laboratory despite trials that were abandoned due to high blood lactate levels above 3.5 mmol x l-1. In order to avoid the breath hold breaking point, the maximum heart rate had to correspond to the heart rate of the ventilatory threshold measured in the laboratory, minus the variations of bradycardia measured at rest. CONCLUSIONS: For the training coach, bradycardia was determined by water immersion during a static breath hold. This permitted an evaluation of the level of diver training. A maximal heart rate was attempted to avoid the breath hold breaking point. The results of this study may be useful in creating an effective diver training program.

Breath-holding time: effects of non-chemical factors in divers and non-divers.

Two main factors (chemical and non-chemical factors) are involved in the determination of breath-holding time (BHT). Earlier studies have shown that chemical factors can be modified by training. The aim of this study was to establish whether BHT can be lengthened or shortened by changes in non-chemical factors according to the degree of training of the divers. Hyperoxic hypercapnic rebreathing challenges interrupted by different periods of voluntary apnoea (20, 40 and 50 s) were performed by divers (n=8) and non-divers (n=6). The relationships between ventilation (VE) and end-tidal PCO2 and mean inspiratory flow (VT/TI) where VT is the tidal volume and TI the inspiration time) and end-tidal PCO2 were measured before (pre) and after (post) apnoea for each population. The slopes of these linear regressions (VEs and VT/TI,s, respectively) reflected respiratory centre activity. VFs-post and VT/TIs-post increased with BHT and were higher in the non-divers than in divers. There were no significant differences between VFs-pre and VFs-post or between VT/TIs,-pre and VT/TIs-post in divers for all BHT. However, in non-divers, significant differences between pre and post values appeared at 20, 40 and 50 s for VT/TI,s and at 40 and 50 s for VEs. Non-chemical factorswere obtained by calculating the differences between pre and post values and were different at 20 and 40 s for VEs (P<0.05) and for all BHT for VT/TI,s (P<0.05). The non-chemical factors increased significantly with BHT and were higher in the non-divers. These adaptations in divers may modify the breath-hold breaking point and consequently increase BHT.

Ventilatory responses to hypercapnia in divers and non-divers: effects of posture and immersion.

The aim of this study was to determine the effects on respiratory drive of two factors, one mechanical (lung volume) and one chemical (sensitivity to hypercapnia), that are involved in determining the breath-hold duration (BHD). Functional residual capacity was measured by helium dilution with the subject seated in air, seated in water and in the prone position in water. Hyperoxic hypercapnia rebreathing (Read's method) was carried out under identical environmental conditions to assess the effects of CO2 pressure on respiratory centre output by measuring ventilation, mean inspiratory flow and occlusion pressure. Sixteen healthy volunteers were tested. 8 trained divers and 8 non-divers. Functional residual capacity decreased for the postures seated in water (30.8%-34.8%) and for prone position in water (20.3%-20.9%) when compared to the posture seated in air (P<0.0001), all subjects pooled. No difference was found between groups. The slopes of the linear regression, which characterised the sensitivity to CO2 and were determined with the rebreathing tests, revealed differences between the two populations (ventilation: P < 0.0001; mean inspiratory flow: P < 0.05). No difference was found for occlusion pressure or between the different postures. These results confirmed a lower sensitivity to CO2 for trained divers. This adaptation was shown to decrease respiratory centre activity at the origin of the breath-hold breaking point. The immersion, did not influence respiratory drive, despite a decrease in lung volumes. The authors suggest that these findings may be explained by a specific apnoea training and a pronounced bradycardia in immersion.

Spatial and temporal gait variable differences between basketball, swimming and soccer players.

The gait variables of 10 swimmers, 10 basketball players, and 16 soccer players were compared. They were all male and right-handed. There was no statistical difference between the three groups in age, weight and height. Spatial and temporal gait variables were measured with the Bessou gait analyzer. In the swimmers group, the gait variables of the right side were not statistically different from those of the left side. The right propulsion double support duration, right cycle duration, and right late swing phase duration were respectively longer than those on the left side for the basketball players. The right propulsion double support duration, right step length, and right late swing phase duration were higher than those on the left side for the soccer players. Moreover, a discriminant analysis performed with the gait variables permitted significant differentiation between the three groups. In conclusion, both basketball and soccer players presented asymmetrical gait variables, that have never been previously reported in normal subjects, or in swimmers. These results suggest that the anticipatory postural adjustments programmed to be used just before a jump or a shoot influence the motor program of the spontaneous locomotion. These gait asymmetries could also be due to asymmetric muscle development.