The effect of an Olympic distance triathlon on the respiratory muscle strength and endurance in triathletes.

High-intensity exercise, marathons, and long distances triathlons have been shown to induce the fatigue of respiratory muscles (RMs). Never-theless, fatigue and the recovery period have not been studied in re-sponse of an Olympic distance triathlon (1.5-km swim, 40-km bike, 10-km run: short-distance triathlon). The aim of this study was to evaluate the RM fatigue induced by an Olympic distance triathlon. Nine male triath-letes (24±1.1 years) underwent spirometric testing and the assessment of RM performance. Respiratory function tests were conducted in sit-ting position. Spirometric parameters, maximal inspiratory and expirato-ry pressures, and RM endurance assessed by measuring the time limit were evaluated before (pre-T), after (post-T), and the day following the triathlon (post-T-24 hr). Residual volume increased: pre-T vs. post-T (P<0.002), maximal inspiratory pressure significantly decreased from 127.4±17.2 (pre-T) to 121.6±18.5 cmH2O (post-T) (P<0.001) and returned to the pre-T value 24 hr after the race (125.0±18.6). RM endurance sig-nificantly decreased from 4:51±0:8 (pre-T) to 3:13±0:7 min (post-T, P< 0.001) and then remained decreased for 24 hr after the race from 4:51± 0:8 (pre-T) to 3:39±0:4 min 24 hr after (P<0.002). Both, strength and en-durance of inspiratory muscles decrease after Olympic distance triath-lon. Furthermore, the impaired of inspiratory muscle endurance 24 hr after the race suggested a slow recovery and persistence of inspiratory muscle fatigue.

Genetic advantageous predisposition of angiotensin converting enzyme id polymorphism in Tunisian athletes.

BACKGROUND: ID polymorphism of the gene coding for the angiotensin I-converting enzyme (ACE) represents a determining factor in physical and athletic performance in the context of genetic conditioning of sports predisposition. The aim of this study was to show the potential importance of genetic factors in relation to the athletic status in Tunisian athletes. METHODS: The ACE genotypes were established using polymerase chain reaction (PCR) amplification for 282 Tunisian athletes (endurance: N.=149 - power: N.=133), and 211 sedentary volunteers. RESULTS: No significant difference was found in the ACE genotype distribution between athletes (36% DD, 49% ID, 15% II) and controls (CTR) (39% DD, 46% ID, 15% II; P=0.72). In contrast, a high significant difference between endurance and power groups were noted in genotype and alleles (χ2=10.32, P=0.0057; χ2=4,752, P=0.029, respectively). The elite endurance-athletes (N.=72) possess some inherent genetic advantage predisposing them to superior athletic performances compared to CTR for ACE alleles (χ2=3.51, P=0.06). In addition endurance trained athletes were also significantly different from CTR for ACE genotype (χ2=6.05, P=0.04). Furthermore, a significant difference have been found between elite power-athletes (N.=59) and CTR for ACE alleles (χ2=3.79, P=0.05). CONCLUSIONS: Tunisian athletes exhibit insertion (I) and deletion (D) alleles of the ACE polymorphism associated with a high level of human endurance and power performance, respectively. This genetic background plays an important role in sporting potential and causes some individuals to be better adapted to specific physical training. This should be considered in athlete development to identify which sporting specialties should be trained for Tunisian talent promotion.

Fortuitous description of hemoglobin Hope in a high-level Tunisian athlete: molecular diagnosis and origin.

In this study we report the fortuitous description of hemoglobin (Hb) Hope in a Tunisian athlete. This Hb is one of hemoglobin variants that show a lower stability and oxygen affinity that is beneficial to tissue oxygen delivery. Hb Hope was isolated by automated high performance liquid chromatography and was unequivocally found to be Hb Hope using DNA-based methods: polymerase chain reaction, denaturing gradient gel electrophoresis, direct DNA sequencing. Restriction haplotype showed that this Hb was supported by the Mediterranean haplotype I. Hb Hope was identified at first in a black African-American family and later in several other black and non black ethnic groups. All these descriptions raise the question of the Hb Hope origin. Recently, Hb Hope was reported in Thai in association with the same Mediterranean haplotype I. This favors that Tunisian and Thai Hb Hope would share a common Mediterranean origin, thus suggesting the possibility of a Mediterranean gene flow. On another hand, the observation of Hb Hope in a high level athlete would suggest a selection pressure of this Hb variant due to higher physical aptitude.

The epidemiology of abnormal hemoglobins in Mediterranean high-level athletes.

The aim of this study was to determine the prevalence and nature of hemoglobin (Hb) defects in a Mediterranean high-level (HL) athlete population. Five hundred and ninety-four HL male and female athletes were recruited during the annual follow-up of the members of Tunisian national teams. Hematological data, Hb electrophoresis, and DNA analysis were assessed using conventional techniques. Sporting discipline, type of sport, and performance levels were assessed using a questionnaire. The results showed that 32 HL athletes had abnormal Hb (5.4%): beta-thalassemia (2.2%), alpha-thalassemia (0.5%), HbAS (1.5%), HbAC (0.5%), and rare Hb variants (0.7%). Of the 32 defect carriers, all but one (a alpha-thalassemia) were heterozygous. All the detected hemoglobinopathies but one (an Hb Hope) had already been reported in the country. The prevalence of Hb defect in the HL athletes was similar to that described in the general Tunisian population (P > 0.05). The percentage of Hb defect in the athletes was not dependent on gender, or performance level (P > 0.05). Within each type of sport the percentages of athletes with normal and abnormal Hb were similar (P > 0.05). The hematological data revealed the diversity of anemia, microcytosis, and hypochromia in thalassemic HL athletes. We concluded that HL athletes in Tunisia were a representative sample of the general Tunisian population regarding the prevalence and nature of benign abnormal Hb. The hematological data of the thalassemia carriers exhibited high variability and raised the question of genetic and sporting counseling, as well as biological follow-up for these carriers.

Cycling performance and mechanical variables using a new prototype chainring.

The primary aim of our study was to examine supra-maximal cycling performance and related mechanical variables in trained cyclists using a new prototype chainring (PC) designed to produce a higher mean net torque (T (N mean)) than a standard chainring (SC). The main feature of the PC is that crank-arm alignment and lever-arm length change as a function of the crank angle during the pedaling cycle. The PC presents two features theorized to effect cycling performance: (1) out of line of pedal cranks resulting in an decrease in the dead points, and (2) a change in crank arm length inducing a torque different from that of SC during the down- and up-stroke of the pedaling cycle. To investigate this theory, we examined eight male cyclists who performed a 1-km "all-out" cycling test in the following order: SC, PC, and SC. Performance was measured as the time (s) to complete the 1-km test. Mechanical variables included torque (N m(-1)), crank velocity (rad s(-1)), and power output (W). We performed our statistical analysis using a two-way ANOVA for repeated measurements and Newman-Keuls post hoc assessment. Our results showed that performance was similar for SC (69.41 +/- 6.69 s) and PC (73.33 +/- 4.58 s). Torque, crank velocity, and power output were also similar throughout (P > 0.05). We conclude that despite the theoretically benefits proposed by the inventors the new PC investigated in our study failed to improve cycling performance or mechanical variables during a supramaximal test when compared with SC.

Exercise intensity during repeated days of racing in professional triathletes.

The purpose of this study was to estimate the exercise intensity from the competition heart rate (HR) of professional triathletes during a multi-triathlon race. Five internationally ranked professional triathletes completed incremental cycling and running tests to assess the first and second ventilatory thresholds (i.e., VT and RCT) and the HR at VT and RCT. HR was then monitored during a 5 d multi-triathlon race: a prologue time trial (PTT, 0.2 km swim -- 5 km cycle -- 1.2 km run) that opened the race; short-distance triathlons (SHD; 1.3 km swim -- 36 km cycle -- 8.4 km run) performed on the 2nd and 5th days; and sprint-distance triathlons (SPD; 0.75 km swim -- 20 km cycle -- 5 km run) performed on the 3rd and 4th days. All trials except the last (i.e., the second SHD) were performed above HR corresponding to RCT. PTT elicited significantly higher mean HR than the other trials (except for the first SPD trial). In contrast, the last SHD elicited significantly lower HR than the other trials. These responses were globally similar in the 3 segments (i.e., swim, cycle, and run). This study demonstrates that the triathletes performed at very high intensity during a drafting-permitted multi-triathlon race. However, as shown for multi-day cycling distances, the HR responses depended on (i) the distance covered and (ii) group behavior.

A systems model of training for patients in phase 2 cardiac rehabilitation.

BACKGROUND: The aim of this study was to apply a systems model of training for athletes in patients with coronary artery disease (CAD) undergoing phase 2 cardiac rehabilitation. METHODS: Data from six patients with CAD undergoing 20 conventional training sessions were used to test this model. The method required daily training quantification using heart rate, and regular assessment of real exercise tolerance using a constant-duration test. Convolution of training quantity with real exercise tolerance was provided for every patient model exercise tolerance, by minimizing the residual sum of squares. RESULTS: The results showed that application of the systems model of training to the six patients resulted in a strong fit between real and model exercise tolerances: r(2) = 0.77, 0.79, 0.83, 0.84, 0.85 and 0.92, respectively (P < 0.05). DISCUSSION: Moreover, the systems model admitted for all patients corresponded to one first-order transfer function, which was fitness. This result was in contrast with the systems models reported in athletes and in a patient with CAD undergoing phase 3 cardiac rehabilitation which were found to include two first-order transfer functions: fitness and fatigue, simultaneously. CONCLUSION: The systems model of training of patients with CAD undergoing phase 2 suggested two practical consequences: first, the improvement of exercise tolerance is directly related to training, and consequently second, patients who enter immediately phase 3 training may prevent a decrease in their exercise tolerance.

Applying a systems model of training to a patient with coronary artery disease.

PURPOSE: The aim of the present study was to apply a systems model of training for athletes to a patient with coronary artery disease (CAD) undergoing phase 3 rehabilitation. METHODS: A patient with CAD underwent 14 wk of training during which exercise was quantified using intensity and duration. Real exercise tolerance was assessed twice a week during this period using a constant-load test. The model exercise tolerance was obtained by convolving the quantified training to real exercise tolerance. The model parameters were obtained by fitting the real exercise tolerance to model exercise tolerance by the least square method. These parameters were then used to calculate the time needed after a training impulse to reach maximal tolerance (tg) and then to return to the pretraining level of tolerance (ti). RESULTS: The results showed that: 1) the fit between real and model exercise tolerances was significant (r = 0.73, P < 0.05), and 2) tg and ti were predicted 17 and 120 d posttraining, respectively. CONCLUSIONS: The application of a systems model of training for athletes to a patient with CAD was successful. We were able to predict the maximal exercise tolerance and the duration of increased tolerance subsequent to the training period.

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: eta(b); changes in plasma volume: deltaPV) 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 ( VO(2max)). The DLco was measured before and 10 min after trials. ANF and deltaPV 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 deltaDLco decrease, a lower ANF concentration and a lower deltaPV than did CR, whereas for both CR and RC eta(b) was increased throughout exercise and 10 min after. In addition, after CR the deltaDLco decrease was inversely correlated ( r=-0.764; P<0.01) with deltaPV. The association of decreased plasma volume, increased eta(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 deltaPV and deltaDLco 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.