Concurrent Validity and Reliability of Manual Versus Specific Device Transcostal Measurements for Breathing Diaphragm Thickness by Ultrasonography in Lumbopelvic Pain Athletes.

The use of rehabilitative ultrasound imaging (RUSI) to evaluate diaphragm thickness during breathing in athletes who suffer from non-specific lumbopelvic pain presents some measurement errors. The purpose of this study was to evaluate intra- and inter-sessions, intra- and inter-rater reliabilities, and concurrent validity of diaphragm thickness measurements during breathing using transcostal RUSI with a novel thoracic orthotic device that was used to fix the US probe versus those measurements obtained using manual fixation. A total of 37 athletes with non-specific lumbopelvic pain were recruited. Intra- (same examiner) and inter-rater (two examiners) and intra- (same day) and inter-session (alternate days) reliabilities were analyzed. All measurements were obtained after manual probe fixation and after positioning the thoracic orthotic device to fix the US probe in order to correctly correlate both measurement methods. Both left and right hemi-diaphragm thickness measurements were performed by transcostal RUSI at maximum inspiration, expiration, and the difference between the two parameters during relaxed breathing. Intra-class correlation coefficients (ICC), standard errors of measurement (SEM), minimum detectable changes (MCD), systematic errors, and correlations (r) were assessed. Orthotic device probe fixation showed excellent reliability (ICC = 0.852-0.996, SEM = 0.0002-0.054, and MDC = 0.002-0.072), and most measurements did not show significant systematic errors (p > 0.05). Despite manual probe fixation with a reliability ranging from good to excellent (ICC = 0.714-0.997, SEM = 0.003-0.023, and MDC = 0.008-0.064 cm), several significant systematic measurement errors (p < 0.05) were found. Most significant correlations between both orthotic device and manual probe fixation methods were moderate (r = 0.486-0.718; p < 0.05). Bland-Altman plots indicated adequate agreement between both measurement methods according to the agreement limits. The proposed novel thoracic orthotic device may allow ultrasound probe fixation to provide valid and reliable transcostal RUSI measurements of diaphragmatic thickness during relaxed breathing thus reducing some measurement errors and avoiding systematic measurement errors. It may be advisable to measure diaphragm thickness and facilitate visual biofeedback with respect to diaphragm re-education during normal breathing in athletes with non-specific lumbopelvic pain.

Effects of vibration training and detraining on balance and muscle strength in older adults.

The purpose of this study was to analyze the effects of 2 days/week versus 4 days/week of Whole Body Vibration (WBV) during eight weeks of WBV training on health-related quality of life (SF-36), balance and lower body strength, as well as short-term detraining (3 weeks) on balance and lower body strength among older adults. Thirty-four older adults were randomly assigned to a control group (Control; n = 11) or to one of the vibration training groups: WBV 2 days/week (WBV_2d; n = 11) or WBV 4 days/week (WBV_4d; n = 12). The WBV groups exercised for 8 weeks, following 3 weeks of detraining. Lower body strength increased significantly (p < 0.05) for both groups, WBV_2d and WBV_4d, after 8-week training. A significant reduction in strength was observed following 3 weeks of detraining only in WBV_2d group (p < 0.05). All variables of the SF-36 and the balance test did not change after intervention in any group. 2 days/week and 4 days/week of WBV during 8 weeks showed the same improvements on muscle strength. 3 weeks of detraining did not reverse the gains in strength made during 32 sessions of WBV. Key points2 days and 4 days per week of WBV training during 8 weeks showed the same improvements on muscle strength.3 weeks of detraining did not reverse the gains in strength made during 32 sessions of WBV exercise.3 weeks of detraining did reverse the gains in strength made during 16 sessions of WBV exercise.

PPARGC1A genotype (Gly482Ser) predicts exceptional endurance capacity in European men.

Animal and human data indicate a role for the peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PPARGC1A) gene product in the development of maximal oxygen uptake (V(O2 max)), a determinant of endurance capacity, diabetes, and early death. We tested the hypothesis that the frequency of the minor Ser482 allele at the PPARGC1A locus is lower in World-class Spanish male endurance athletes (cases) [n = 104; mean (SD) age: 26.8 (3.8) yr] than in unfit United Kingdom (UK) Caucasian male controls [n = 100; mean (SD) age: 49.3 (8.1) yr]. In cases and controls, the Gly482Ser genotype met Hardy-Weinberg expectations (P > 0.05 in both groups tested separately). Cases had significantly higher V(O2 max) [73.4 (5.7) vs. 29.4 ml x kg(-1) x min(-1) (3.8); P < 0.0001] and were leaner [body mass index: 20.6 (1.5) vs. 27.6 kg/m2 (3.9); P < 0.0001] than controls. In unadjusted chi2 analyses, the frequency of the minor Ser482 allele was significantly lower in cases than in controls (29.1 vs. 40.0%; P = 0.01). To assess the possibility that genetic stratification could confound these observations, we also compared Gly482Ser genotype frequencies in Spanish (n = 164) and UK Caucasian men (n = 381) who were unselected for their level of fitness. In these analyses, Ser482 allele frequencies were very similar (36.9% in Spanish vs. 37.5% in UK Caucasians, P = 0.83), suggesting that confounding by genetic stratification is unlikely to explain the association between Gly482Ser genotype and endurance capacity. In summary, our data indicate a role for the Gly482Ser genotype in determining aerobic fitness. This finding has relevance from the perspective of physical performance, but it may also be informative for the targeted prevention of diseases associated with low fitness such as Type 2 diabetes.

Frequency of the C34T mutation of the AMPD1 gene in world-class endurance athletes: does this mutation impair performance?

The C34T mutation in the gene encoding for the skeletal muscle-specific isoform of AMP deaminase (AMPD1) is a common mutation among Caucasians (i.e., one of five individuals) that can impair exercise capacity. The purpose of this study was twofold. First, we determined the frequency distribution of the C34T mutation in a group of top-level Caucasian (Spanish) male endurance athletes (cyclists and runners, n = 104). This group was compared with randomly selected Caucasian (Spanish) healthy (asymptomatic) nonathletes (n = 100). The second aim of this study was to compare common laboratory indexes of endurance performance (maximal oxygen uptake or ventilatory thresholds) within the group of athletes depending on their C34T AMPD1 genotype. The frequency of the mutant T allele was lower (P < 0.05) in the group of athletes (4.3%) compared with controls (8.5%). On the other hand, indexes of endurance performance did not differ (P > 0.05) between athlete carriers or noncarriers of the C34T mutation (e.g., maximal oxygen uptake 72.3 +/- 4.6 vs. 73.5 +/- 5.9 ml.kg(-1).min(-1), respectively). In conclusion, although the frequency distribution of the mutant T allele of the AMPD1 genotype is lower in Caucasian elite endurance athletes than in controls, the C34T mutation does not significantly impair endurance performance once the elite-level status has been reached in sports.

Tour de France versus Vuelta a España: which is harder?

PURPOSE: To compare the total exercise loads (intensity x volume) of the Vuelta a España and Tour de France during the last year. METHODS: Seven professional road cyclists (28 +/- 1 yr; [OV0312]O(2max): 74.6 +/- 2.2 mL.kg-1.min-1) who participated in both Tour and Vuelta during the years 1997, 1999, 2000, or 2001 were collected as subjects. They wore a heart rate (HR) telemeter during each stage of the two races, and exercise intensity was divided into three phases according to the reference HR values obtained during a previous ramp cycle-ergometer test: phase I (RCP). Total volume and intensity were integrated as a single variable. The score for volume x intensity in each phase was computed by multiplying the accumulated duration in this phase by a multiplier for this particular phase. The total score for Tour and Vuelta was obtained by summating the results of the three phases. RESULTS: The total loads (volume x intensity) did not significantly differ between the two races (P > 0.05), despite a significantly longer total exercise time of the Tour (P < 0.05) (5552 +/- 176 vs 5086 +/- 290 min). CONCLUSION: The physiological loads imposed on cyclists' bodies do not differ between the Tour and Vuelta, despite the longer duration of daily stages in the former race.

Inverse relationship between VO2max and economy/efficiency in world-class cyclists.

PURPOSE: To determine the relationship that exists between VO2max and cycling economy/efficiency during intense, submaximal exercise in world-class road professional cyclists. METHODS Each of 11 male cyclists (26+/-1 yr (mean +/- SEM); VO2max: 72.0 +/- 1.8 mL x kg(-1) x min(-1)) performed: 1) a ramp test for O2max determination and 2) a constant-load test of 20-min duration at the power output eliciting 80% of subjects' VO2max during the previous ramp test (mean power output of 385 +/- 7 W). Cycling economy (CE) and gross mechanical efficiency (GE) were calculated during the constant-load tests. RESULTS: CE and GE averaged 85.2 +/- 2.3 W x L(-1) x min(-1) and 24.5 +/- 0.7%, respectively. An inverse, significant correlation was found between 1) VO2max (mL x kg(-0.32) x min(-1)) and both CE (r = -0.71; P = 0.01) and GE (-0.72; P = 0.01), and 2) VO2max (mL x kg(-1) x min(-1)) and both CE (r = -0.65; P = 0.03) and GE (-0.64; P = 0.03). CONCLUSIONS: A high CE/GE seems to compensate for a relatively low VO2max in professional cyclists.

Curvilinear VO(2):power output relationship in a ramp test in professional cyclists: possible association with blood hemoglobin concentration.

The purpose of this study was to determine (1) if there exists an additional, nonlinear increase (DeltaVO(2)) in the oxygen uptake observed (VO2 (obs)) at the maximal power output reached during a ramp cycle ergometer test and that expected (VO2 (exp)) from the linear relationship between VO(2) and power output below the lactate threshold (LT) in professional riders, and (2) the relationship between DeltaVO(2) and possible explanatory mechanisms. Each of 12 professional cyclists (25 +/- 1 years; VO(2 max): 71.3 +/- 1.2 ml x kg(-1) x min(-1)) performed a ramp test until exhaustion (power output increases of 25 W x min(-1)) during which several gas-exchange and blood variables were measured (including lactate, HCO(3)(-) and K(+)). VO(2) was linearly related to power output until the LT in all subjects. Afterward, a nonlinear deflection was observed in the VO(2):power output relationship (DeltaVO(2) = 2492 +/- 55 ml x min(-1) and p < 0.05 for VO2 (obs) vs. VO2 (exp)). A significant negative correlation was encountered between DeltaVO(2) and resting hemoglobin levels before the tests (r = 20.61; p < 0.05). In conclusion, professional cyclists exhibit an attenuation of the VO(2) rise above the LT.

Kinetics of VO(2) in professional cyclists.

PURPOSE: To analyze the kinetics of oxygen uptake (VO(2)) in professional road cyclists during a ramp cycle ergometer test and to compare the results with those derived from well-trained amateur cyclists. METHODS: Twelve professional cyclists (P group; 25 +/- 1 yr; maximal power output (W(max)), 508.3 +/- 9.3 watts) and 10 amateur cyclists (A group; 22 +/- 1 y; W(max), 429.9 +/- 8.6 watts) performed a ramp test until exhaustion (power output increases of 25 watts x min(-1)). The regression lines of the VO(2):power output (W) relationship were calculated for the following three phases: phase I (below the lactate threshold (LT)), phase II (between LT and the respiratory compensation point (RCP)), and phase III (above RCP). RESULTS: In group P, the mean slope (Delta VO(2):Delta W) of the VO(2):W relationship decreased significantly (P < 0.01) across the three phases (9.9 +/- 0.1, 8.9 +/- 0.2, and 3.8 +/- 0.6 mL O(2) x watts(-1) x min(-1) for phases I, II, and III, respectively). No significant differences (P > 0.05) were found between phases I and II (P > 0.05) in group A, whereas Delta VO(2):Delta W significantly increased in phase III (P < 0.01), compared with phase II (10.2 +/- 0.3, 9.2 +/- 0.4, and 10.1 +/- 1.1 mL O(2) x watts(-1) x min(-1) in phases I, II, and III, respectively). The mean value of Delta VO(2):Delta W for phase III was significantly lower in group P than in group A (P < 0.01). CONCLUSION: Contrary to the case in amateur riders, the rise in VO(2) in professional cyclists is attenuated at moderate to high workloads. This is possibly an adaptation to the higher demands of their training/competition schedule.

Determinants of VO(2) kinetics at high power outputs during a ramp exercise protocol.

PURPOSE: To determine the relationship between the additional, nonlinear increase in oxygen uptake (Delta VO(2)) that occurs at high power outputs during a ramp cycle ergometer test, on one hand; and possible explanatory mechanisms of the phenomenon, such as cardiorespiratory work, blood lactate, fitness level, or muscle fiber distribution, on the other. METHODS: Ten healthy, sedentary young adults (age (mean +/- SEM), 22 +/- 1 yr) were chosen as subjects. A muscle biopsy specimen was taken from the vastus lateralis of the right leg to determine fiber type distribution by immunohistochemical identification of myosin heavy chain (MHC) isoforms. During the ramp tests (power output increases of 5 W every 15-s interval), the ventilatory threshold (VT) and lactate threshold (LT) were measured. We defined Delta VO(2) as the difference between "true" VO(2) values observed at the maximal power output (VO(2)obs) and those expected (VO(2)exp) from the previous linear VO2:power output relationship below the VT. RESULTS: A nonlinear increase was observed in VO2 (Delta VO(2) = 239 +/- 79 mL x min(-1), P < 0.05 for VO(2)obs vs VO(2)exp), which was significantly correlated with the percentage of type IIX fibers (r = 0.80, P < 0.05). No other correlations were found between Delta VO(2) and possible explanatory mechanisms. CONCLUSION: A greater percentage of type IIX fibers is associated with a higher excess VO(2) at high power outputs (above VT).