Predictors of weight loss in Parkinson's disease: is weight loss the chicken or the egg?
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Disease Progression↗
Biomedical subjects
Olivier Hue
Publications and source records attributed to Olivier Hue.
Plasma concentration of organochlorine compounds is associated with age and not obesity.
It has been suggested that obese individuals, because of an increased dilution space (body fat) for lipophilic organochlorines compounds, may have greater levels of toxic pollutants than lean sedentary individuals. It is important to further examine this possibility because of the potential contribution of organochlorine pesticides in the development of Parkinson's disease and other neurological diseases. The aim of this study was to further investigate the relationship between the magnitude of obesity and the plasma concentration of organochlorines for a wide range of BMI (with participants at steady state body weight). Fifty-three individuals were selected on the basis of their body mass index (BMI): lean controls (n=16; mean BMI 22.8+/-2.2 kg/m(2); mean age 38.8+/-9.4 years), obese individuals (n=19; mean BMI 33.4+/-3.0 kg/m(2); mean age 38.6+/-7.6 years) and morbidly obese individuals (n=18; mean BMI 49.3+/-6.5 kg/m(2); mean age 44.3+/-9.2 years). Blood samples were analyzed for organochlorine compounds. The relationship between the total plasma organochlorine concentration and BMI was tested using a multiple regression analysis. Age was included in the model. There was no relationship between the total plasma organochlorine concentration and BMI. Organochlorine concentrations, however, were correlated with age (BMI-adjusted R(2)=0.46; p<0.001). At steady state body weight, toxic pollutant concentrations are not associated to obesity but strongly correlate with age.
Adult↗
Body weight is a strong predictor of postural stability.
Proper balance control is a key aspect of acitivities of daily living. The aim of this study was to determine the contribution of body weight to predict balance stability. The balance stability of 59 male subjects with BMI ranging from 17.4 to 63.8kg/m(2) was assessed using a force platform. The subjects were tested with and without vision. A stepwise multiple regression analysis was used to determine the independent effect of body weight, age, body height and foot length on balance stability (i.e., mean speed of the center of foot pressure). With vision, the stepwise multiple regression revealed that body weight accounted for 52% of the variance of balance stability. The addition of age contributed a further 3% to explain balance control. Without vision, body weight accounted for 54% of the variance and the addition of age and body height added a further 8% and 1% to explain the total variance, respectively. The final model explained 63% of the variance. A decrease in balance stability is strongly correlated to an increase in body weight. This suggests that body weight may be an important risk factor for falling. Future studies should examine more closely the combined effect of aging and obesity on falling and injuries and the impact of obesity on the diverse range of activities of daily living.
Adult↗
The use of an eccentric chainring during an outdoor 1 km all-out cycling test.
This study assessed whether an eccentric chainring that increases crank arm length at the downstroke and decreases it during the upstroke improves performance in a track cycling event: the 1000m time trial. It also determined whether selected physical and physiological variables and the velocity profile are associated with eccentric chainring performance. Twelve cyclists performed an outdoor 1000m time trial on a 333m banked, cement-surfaced track using two different chainrings, round and eccentric, in randomised order. The important findings of this study were that (1) performance did not significantly differ between chainrings; (2) neither the physiological variables (lactate and heart rate) nor the velocity profile (lap times) were affected by use of the eccentric design; (3) when time was saved with the eccentric chainring, it was significantly correlated with estimated lower limb muscle volume (r=-0.605), circumference (r=-0.739), estimated calf muscle volume (r=-0.772) and cross-sectional area (r=-0.745). Moreover, estimated lower limb muscle volume (r=-0.703), estimated calf muscle volume (r=-0.772) and cross-sectional area (r=-0.871) significantly predicted performance with the eccentric chainring. The physical variables associated with eccentric chainring performance were muscle anthropometric parameters. We have interpreted our results cautiously and suggest that the subjects who had greater lower limb muscle volume and greater calf muscle volume, seem to have had a significant advantage in performing with the eccentric chainring. Further testing with track specialists performing at national or international level would be helpful to define the maximal possibilities of this chainring.
Adolescent↗
Comments on Point:Counterpoint series "Lactic acid accumulation is an advantage/disadvantage during muscle activity".
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Acidosis, Lactic↗
Effects of short supramaximal exercise on hemorheology in sickle cell trait carriers.
This study compared the hemorheological profile at rest and in response to a short supramaximal exercise test between sickle cell trait (SCT) carriers and a control group. Eight SCT carriers and eight control subjects performed a ramp exercise test on a cycle ergometer conducted to maximal oxygen uptake (VO2max). One week later, they performed a supramaximal exercise test consisting of pedaling for 1 min at 110% VO2max. Blood viscosity (eta(b)), plasma viscosity (eta(p)), hematocrit (Hct) and red blood cell (RBC) rigidity were assessed at rest, at the end of exercise and at the 15th, 30th and 60th min of recovery. Exercise increased eta(b), eta(p) and Hct above resting values in both groups and these parameters remained higher until the 15th or 30th min of recovery as compared to resting values. RBC rigidity was unchanged from baseline values in both groups during exercise and recovery. No difference was observed between the two groups for eta(p) and Hct but eta(b) and RBC rigidity were higher in the SCT carriers at every time point compared with the control group. The higher RBC rigidity and eta(b) found in SCT carriers at rest and in response to a brief supramaximal exercise might constitute a risk factor for microcirculatory complications. Indeed, a short supramaximal exercise test may not be completely inoffensive for SCT carriers.
Adult↗
Does higher red blood cell (RBC) lactate transporter activity explain impaired RBC deformability in sickle cell trait?
Lactate and H(+) are suggested to promote the sickling process in red blood cells (RBCs) containing hemoglobin S. We demonstrated greater activity of the RBC monocarboxylate cotransporter MCT-1, lower RBC deformability and impaired hematological indices in sickle cell trait (SCT) carriers compared to control subjects, suggesting an involvement of MCT-1 in hemorheological disturbances in SCT carriers.
Adolescent↗
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.
Adult↗
Increased plasma levels of toxic pollutants accompanying weight loss induced by hypocaloric diet or by bariatric surgery.
BACKGROUND: Weight loss reduces the risk of several diseases. Increases of plasma organochlorine and pesticide compounds, however, have been observed with weight loss induced by a dietary intervention and by a gastroplasty. This increased concentration of toxic pollutants could be a side-effect of weight loss and a risk for health problems. The aim of this study was: 1) to observe if there is a relationship between the plasma concentration of organochlorines and BMI at steady state weight, and 2) to determine, after a bariatric surgical intervention, if the magnitude of the weight loss has a direct effect on this concentration. METHODS: Weight loss was obtained in obese individuals by a hypocaloric diet program until resistance and in morbidly obese individuals by a bariatric operation (biliopancreatic diversion - duodenal switch [BPD-DS]). Normal-weight individuals were tested to serve as controls. Blood samples were analyzed for organochlorine and pesticide compounds at baseline in all groups, after resistance to weight loss in obese individuals, and at 3 months and 1 year after surgery in morbidly obese individuals. RESULTS: At steady state weight, organochlorine and pesticide compounds were found in all groups, and the sum of all organochlorine compounds correlated with age and not BMI. Weight loss averaged 12.1% of the initial body weight after dieting and 20.9% at 3 months after surgery, respectively. This weight loss yielded significant increases in total plasma organochlorine concentration (increase of 23.8% for obese and 51.8% for morbidly obese individuals). For morbidly obese individuals, the weight loss at 1 year after surgery (46.3%) yielded a 388.2% increase in total plasma organochlorine concentration. CONCLUSION: Plasma organochlorine concentration increases with weight loss and is related to the magnitude. Future research will have to determine if: 1) this pollutant concentration remains elevated over time and 2) there are long-term effects of this high concentration on health.
Adult↗
Faster lactate transport across red blood cell membrane in sickle cell trait carriers.
The physical and physiological behavior of sickle cell trait carriers (AS) is somewhat equivocal under strenuous conditions, although this genetic abnormality is generally considered to be a benign disorder. The occurrence of incidents and severe injuries in AS during exercise might be explained, in part, by the lactic acidosis due to a greater lactate influx into AS red blood cells (RBCs). In the present study, the RBC lactate transport activity via the different pathways was compared between AS and individuals with normal hemoglobin (AA). Sixteen Caribbean students, nine AS and seven AA, performed a progressive and maximal exercise test to determine maximal oxygen consumption. Blood samples were obtained at rest to assess haematological parameters and RBC lactate transport activity. Lactate influxes [total lactate influx and monocarboxylate transporter (MCT-1)-mediated lactate influx] into erythrocytes were measured at four external [14C]-labeled lactate concentrations (1.6, 8.1, 41, and 81.1 mM). The two groups had similar maximal oxygen consumption. Total lactate influx and lactate influx via the MCT-1 pathway were significantly higher in AS compared with AA at 1.6, 41, and 81.1 mM. The maximal lactate transport capacity for MCT-1 was higher in AS than in AA. Although AS and AA had the same maximal aerobic physical fitness, the RBCs from the sickle cell trait carriers took up more lactate at low and high concentrations than the RBCs from AA individuals. The higher MCT-1 maximal lactate transport capacity found in AS suggests greater content or greater activity of MCT-1 in AS RBC membranes.
Adult↗
Morning versus evening power output and repeated-sprint ability.
We investigated the effect of time-of-day on both maximal sprint power and repeated-sprint ability (RSA). Nine volunteers (22+/-4 yrs) performed a RSA test both in the morning (07:00 to 09:00 h) and evening (17:00 to 19:00 h) on different days in a random order. The RSA cycle test consisted of five, 6 sec maximal sprints interspersed by 24 sec of passive recovery. Both blood lactate concentration and heart rate were higher in the evening than morning RSA (lactate values post exercise: 13+/-3 versus 11+/-3 mmol/L(-1), p<0.05). The peak power developed during the first sprint was higher in the evening than morning (958+/-112 vs. 915+/-133 W, p<0.05), but this difference was not apparent in subsequent sprints, leading to a higher power decrement across the 5x6 sec test in the evening (11+/-2 vs. 7+/-3%, p<0.05). Both the total work during the RSA cycle test and the power developed during bouts 2 to 5 failed to be influenced by time-of-day. This suggests that the beneficial effect of time-of-day may be limited to a single expression of muscular power and fails to advantage performance during repeated sprints.
Adult↗
Time of day influences the environmental effects on muscle force and contractility.
PURPOSE: To investigate the effects of environmental temperature and the diurnal increase in body temperature on muscle contractile processes, 11 male subjects performed maximal and submaximal isometric contractions of the knee extensors with recording of the electromyographic activity in four different conditions (morning/neutral, morning/moderately warm and humid, afternoon/neutral, and afternoon/moderately warm and humid). METHODS: The morning experiments were conducted between 0700 and 1900 h, and the afternoon experiments were conducted between 0500 and 0700 h. The mean laboratory temperatures and humidity were 20.5 (+/-1) degrees C + 67 (+/-4)% and 29.5 (+/-0.8) degrees C + 74 (+/-10)% for the neutral and moderately warm and humid conditions, respectively. RESULTS: Results showed a significant diurnal increase in both rectal and skin temperatures whatever the environmental conditions, and an increase in the skin temperature after a 60-min moderately warm exposure. The major finding of this study was an interaction effect of time of day and environmental conditions on the force/electromyographic activity ratio. That suggests that skeletal muscle contractility was differently increased by the passive warm-up effect of a moderately warm exposure, depending on the diurnal variation in body temperature. This conclusion is supported by an increase in force in the morning only after a 60-min warm exposure (+19%) and in a neutral environment only with the diurnal increase in body temperature (+12%). CONCLUSION: In summary, our data showed that both the warm exposure and the diurnal increase in body temperature influence muscle contractility and consequently muscle strength. However, the improvement in muscle contractility after these two passive warm-ups cannot be combined in order to improve force to a greater level.
Adult↗
Effects of active warm-up and diurnal increase in temperature on muscular power.
PURPOSE: To investigate the effects of both an active warm-up (AWU) and the diurnal increase in body temperature on muscular power. METHODS: Eight male subjects performed maximal cycling sprints in the morning (7:00-9:00 a.m.) and afternoon (5:00-7:00 p.m.) either after an AWU or in a control condition. The AWU consisted of 12 min of pedaling at 50% of & OV0312;O2 max inter-spersed with three brief accelerations of 5 s. RESULTS: Rectal temperature, maximal force developed during the cycling sprint, and muscular power were higher in the afternoon than in the morning (P<0.05). Rectal temperature, calculated muscular temperature, and muscular power were higher after AWU than in control condition (P<0.05). CONCLUSIONS: The beneficial effect of an AWU can be combined with that of the diurnal increase in central temperature to improve muscular power.
Adult↗
Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders.
BACKGROUND: The purpose of this efficacy study was to measure the dose-response effect of a free weight-based resistance training program by comparing the effects of two training intensities (low-moderate and high) of the knee extensor (KE) muscles on muscle function, functional limitations, and self-reported disability. METHODS: The authors conducted a single-blinded, randomized, placebo-controlled trial. Twenty-two institutionalized elders (mean age, 81.5 years) were assigned to either high-intensity strength training (HI; n = 8), low-moderate intensity strength training (LI; n = 6), or weight-free placebo-control training (PC; n = 8). The HI group trained at 80% of their 1-repetition maximum and the LI group trained at 40%. All groups performed 3 sets of 8 repetitions, 3 times per week for 10 weeks. Outcome measures included KE maximal strength, KE endurance, and functional performance as assessed by 6-minute walking, chair-rising, and stair-climbing tests, and by self-reported disability. RESULTS: KE strength and endurance, stair-climbing power, and chair-rising time improved significantly in the HI and LI groups compared with the PC group. Six-minute walking distance improved significantly in the HI group but not in the LI group compared with the PC group. Changes observed in HI were significantly different from those observed in the LI group for KE strength and endurance and the 6-minute walking test, with a trend in the same direction for chair-rising and stair-climbing. Changes in strength were significantly related to changes in functional outcomes, explaining 37% to 61% of the variance. CONCLUSIONS: These results show strong dose-response relationships between resistance training intensity and strength gains, and between strength gains and functional improvements after resistance training. Low-moderate intensity resistance training of the KE muscles may not be sufficiently robust from a physiologic perspective to achieve optimal improvement of functional performance. Supervised HI, free weight-based training for frail elders appears to be as safe as lower intensity training but is more effective physiologically and functionally.
Adaptation, Physiological↗
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.
Adult↗
Correlation between heart rate and performance during Olympic windsurfing competition.
The aim of this study was to examine the heart rate (HR) response to Olympic windsurfing competition and to check if there was any correlation between racing HR, performance, and the variables measured during laboratory maximal exercise. Ten elite windsurfers [age: 20.93 (3.46) years; height: 178.10 (6.34) cm; body mass: 66.79 (5.90) kg] performed a laboratory maximal oxygen consumption (.VO(2max)) trial and national windsurf competitions wearing a HR monitor. One hundred and forty-three individual races were examined. Racing HR was expressed as a percentage of (1) HR(max) (maximal treadmill HR) and (2) HR(reserve) (HR(max)-HR(rest)). The performance (racing classification: RC, which is inversely proportional to performance) was significantly correlated to the racing HR response in both light wind (LW): LW-RC=-0.12(%HR(reserve))+13.03; r=-0.71, r(2)=0.50, p<0.001, and medium wind (MW): MW-RC=-0.11(%HR(reserve))+10.99; r=-0.66, r(2)=0.43, p<0.001. The results showed similar correlations between performance and %HR(max). Post racing lactate concentration was higher in LW compared to MW [7.14 (0.21) and 5.18 (2.02) mmol.l(-1), respectively]. There was a negative correlation between the highest racing HR (%HR(reserve)) of each athlete and the second ventilatory threshold expressed as a percentage of .VO(2max) ( r=-0.71, p<0.05). To summarize, this study showed that light and medium wind Olympic windsurfing performances are highly dependent on the capacity of the athlete to maintain a high HR for long periods of time. Furthermore, windsurfing is highly dependent on the athlete's physical fitness level as shown by the correlations between racing HRs and laboratory physiological variables.
Adult↗
Lactic response in sickle cell trait carriers in comparison with subjects with normal hemoglobin.
OBJECTIVE: The objective of this study was to assess lactic response (mmol/L) during incremental exercise in a specific population of men and women with sickle cell trait. SUBJECTS: Athletic men and women from the French West Indies showing no anemia and/or alpha thalassemia. METHODS: Anemia was ruled out by hemoglobin level, and alpha thalassemia was ruled out by hemoglobin S percentage with concomitant hemoglobin level and mean corpuscular volume. Comparison was made with control subjects with normal hemoglobin, matched for physical fitness, anthropometric data, and sex. All subjects performed an incremental exercise test using a cycle ergometer. Peak oxygen uptake (mL/min) was predicted from an equation at peak exercise. Heart rate (beats/min) was noted continuously, and blood samples were collected for lactic response determination every minute during the incremental exercise test and at 1, 3, and 5 minutes of recovery. RESULTS: Comparison of peak oxygen uptake and heart rate values showed no significant differences in subjects with sickle cell trait versus control subjects during the incremental exercise test. In contrast, analysis of variance revealed significantly lower lactic response time courses during the incremental exercise test and at peak exercise (p < 0.05) in the sickle cell trait group, whereas the heart rate time course was lower during recovery (p < 0.05). CONCLUSION: We conclude that the lower lactic response exhibited by subjects with sickle cell trait during incremental exercise was the result of an adaptive process in red blood cells in relation to either lower lactate production or greater lactate uptake capability than in individuals with normal hemoglobin.
Adaptation, Physiological↗
Prediction of drafted-triathlon race time from submaximal laboratory testing in elite triathletes.
PURPOSE AND METHODS: To determine which physiological variables accurately predict the race time of an Olympic-distance International Triathlon undertaken in drafted conditions, 8 elite triathletes underwent both maximal and submaximal laboratory and field physiological testing: a 400-m maximal swim test; an incremental treadmill test; an incremental cycling test; 30 min of cycling followed by 20 min of running (C-R); and 20 min of control running (R) at the exact same speed variations as in running in C-R. Blood samples were drawn to measure venous lactate concentration after the 400-m swim and the cycle and run segments of C-R. During the maximal cycling and running exercises, data were collected using an automated breath-by-breath system. RESULTS: The only parameters correlated with the overall drafted-triathlon time were lactate concentration noted at the end of the cycle segment (r = 0.83, p < 0. 05) and the distance covered during the running part of the submaximal C-R test (r = 0.92, p < 0. 01). Stepwise multiple regression analysis revealed a highly significant (r = 0.96, p < 0.02) relationship between predicted race time (from laboratory measures) and actual race time, using the following calculation: Predicted Triathlon Time (s) = 1.128 (distance covered during R of C-R [m]) + 38.8 ([lactate] at the end of C in C-R) + 13,338. The high R2 value of 0.93 indicated that, taken together, these two laboratory measures could account for 93% of the variance in race times during a drafted triathlon. CONCLUSION: Complementing previous studies, this study demonstrates that different parameters seem to be reliable for predicting performance in drafted vs. nondrafted Olympic-triathlon races. It also demonstrates that, for elite triathletes competing in a drafted Olympic-distance triathlon, performance is accurately predicted from the results of submaximal laboratory measures.
Adult↗