Dynamic MR imaging of cerebral perfusion during bicycling exercise.

Habitual physical activity is beneficial for cerebrovascular health and cognitive function. Physical exercise therefore constitutes a clinically relevant cerebrovascular stimulus. This study demonstrates the feasibility of quantitative cerebral blood flow (CBF) measurements during supine bicycling exercise with pseudo-continuous arterial spin labeling (pCASL) magnetic resonance imaging (MRI) at 3 Tesla. Twelve healthy volunteers performed a steady-state exercise-recovery protocol on an MR-compatible bicycle ergometer, while dynamic pCASL data were acquired at rest, during moderate (60% of the age-predicted supine maximal heart rate (HRmax)) and vigorous (80% of supine HRmax) exercise, and subsequent recovery. These CBF measurements were compared with 2D phase-contrast MRI measurements of blood flow through the carotid arteries. Procedures were repeated on a separate day for an assessment of measurement repeatability. Whole-brain (WB) CBF was 41.2 ± 6.9 mL/100 g/min at rest (heart rate 63 [57-71] beats/min), remained similar at moderate exercise (102 [97-107] beats/min), decreased by 10% to 37.1 ± 5.7 mL/100 g/min (p = 0.001) during vigorous exercise (139 [136-142] beats/min) and decreased further to 34.2 ± 6.0 mL/100 g/min (p < 0.001) during recovery. Hippocampus CBF decreased by 12% (p = 0.001) during moderate exercise, decreased further during vigorous exercise (-21%; p < 0.001) and was even lower during recovery (-31%; p < 0.001). In contrast, motor cortex CBF increased by 12% (p = 0.027) during moderate exercise, returned to resting-state values during vigorous exercise, and decreased by 17% (p = 0.006) during recovery. The inter-session repeatability coefficients for WB CBF were approximately 20% for all stages of the exercise-recovery protocol. Phase-contrast blood flow measurements through the common carotid arteries overestimated the WB CBF because of flow directed to the face and scalp. This bias increased with exercise. We have demonstrated the feasibility of dynamic pCASL-MRI of the human brain for a quantitative evaluation of cerebral perfusion during bicycling exercise. Our spatially resolved measurements revealed a differential response of CBF in the motor cortex as well as the hippocampus compared with the brain as a whole. Caution is warranted when using flow through the common carotid arteries as a surrogate measure for cerebral perfusion.

A combination of oral L-citrulline and L-arginine improved 10-min full-power cycling test performance in male collegiate soccer players: a randomized crossover trial.

PURPOSE: Oral L-citrulline (Cit) increases plasma L-arginine (Arg) concentration and the production of nitric oxide (NO). NO dilates blood vessels and potentially improves sports performance. The combination of oral Arg and Cit (Arg + Cit) immediately and synergistically increases plasma Arg and nitrite/nitrate (NOx) concentrations more than either Cit or Arg alone. This prompted us to assess the effects of oral Arg + Cit on 10-min cycling performance in a double-blind, randomized, placebo-controlled crossover trial. METHODS: Twenty-four male soccer players ingested either Cit + Arg or placebo (both 1.2 g/day each) for 6 days. On day 7, they ingested Cit + Arg 1 h before performing a 10-min full-power pedaling test on a bicycle ergometer. Plasma NOx and amino acid levels were measured before and after the test, as well as the participants' subjective perception of physical exertion. RESULTS: Power output was significantly greater with Cit + Arg than in the placebo group (242 ± 24 vs. 231 ± 21 W; p < 0.05). Plasma concentrations of post-exercise NOx (p < 0.05), Cit (p < 0.01) and Arg (p < 0.01) were significantly higher in the Cit + Arg than in the placebo group, whereas exercise upregulated plasma NOx concentrations in both groups (p < 0.05). Cit + Arg also gave improved post-exercise subjective perception of "leg muscle soreness" and "ease of pedaling" (both p < 0.05). CONCLUSION: Seven days of oral Citrulline (1.2 g/d) and Arginine (1.2 g/d) ingestion improved 10-min cycling performance and the perception of physical exertion in male collegiate soccer players.

Effects of a Thermal Agent and Physical Activity on Muscle Tendon Stiffness, as Well as the Effects Combined With Static Stretching.

CONTEXT: A recent review or article reported that thermal agents (TA) or physical activity (PA) can increase range of motion (ROM) and that the combination of TA with stretching is superior to performing stretching only. However, since ROM is affected by the psychological factors, it is questionable whether these studies measured the effect of these interventions on muscle flexibility. By measuring muscle stiffness, the authors attempted to evaluate the effect these interventions on muscle flexibility. OBJECTIVE: To compare the individual effects of TA and PA on muscle flexibility, as well as their effectiveness when combined with static stretching (SS). DESIGN: Crossover trial. SETTING: University research laboratory. PARTICIPANTS: 15 healthy men without a history of orthopedic disease in their lower limbs. INTERVENTIONS: 15 minutes of 3 different conditions: hot pack as TA, pedaling exercise as PA, and the control group with no TA or PA intervention, followed by 3 min of SS for the hamstrings. MAIN OUTCOME MEASURES: Joint angle and passive torque of the knee during passive elongation were obtained prior to interventions, after 3 kinds of intervention, and after SS. From these data, muscle-tendon-unit (MTU) stiffness of the hamstrings was calculated. RESULTS: Although knee-joint ROM increased with both TA and PA (P < .05), there were no significant differences in MTU stiffness between pre- and postintervention measurements for either of the interventions (TA, P = .477; PA, P = .377; control, P = .388). However, there were similar significant decreases in MTU stiffness between postintervention and post-SS for all conditions (P < .01). CONCLUSIONS: TA and PA did not decrease MTU stiffness, and combining these interventions with SS did not provide additional decreases in MTU stiffness compared with performing SS alone.

Effectiveness of pedalling retraining in reducing bilateral pedal force asymmetries.

Previous studies have been limited to describe asymmetries during pedalling and suggest possible repercussion on performance and/or injury risks. However, few studies have presented strategies to mitigate asymmetries. The purpose of this study was to assess the effectiveness of a pedalling retraining intervention to reduce bilateral pedal force asymmetries. Twenty cyclists were assessed and 10 enrolled in a pedalling retraining method receiving visual and verbal feedback of pedal forces. The asymmetry index was computed for comparison of bilateral peak pedal forces and used during retraining (12 trials at 70% of peak power). Significantly larger asymmetry was observed for asymmetrical cyclists at the first three trials (P < 0.01 and ES = 1.39), which was reduced when post-retraining was compared to measures from symmetrical cyclists (P = 0.69 and ES = 0.18). Cyclists with larger asymmetry (>20%) in bilateral pedal forces reduce their asymmetries using sessions of pedalling retraining and achieve asymmetry indices similar to symmetrical cyclists.

Comparison of the modified shuttle walk test and cardiopulmonary exercise test in sarcoidosis.

BACKGROUND AND OBJECTIVE: Dyspnoea and exercise intolerance are common in sarcoidosis and are often poorly correlated with resting lung function. Measurement of peak exercise capacity is likely to be helpful in assessing and monitoring disease. The aim of this study was to compare the modified shuttle walk test (MSWT) to cardiopulmonary exercise test (CPET) as a measure of peak exercise capacity in sarcoidosis. METHODS: Thirty-three (17 male, mean age 48 years) patients with sarcoidosis completed a standardized exponential exercise protocol cycle ergometer CPET and a single corridor MSWT in random order. RESULTS: Subjects has a mean forced expiratory volume in 1 s (FEV1) 2.4 L (75.7%predicted), forced vital capacity (FVC) 3.43 L (88.7%predicted) and diffusing capacity for carbon monoxide (DLCO) 20.3 mL/min/mm Hg (71.4%predicted). There was a strong correlation between MSWT distance and peak oxygen uptake (VO2) during CPET (r = 0.87; P < 0.0001), and between maximum heart rate during MSWT and CPET (r = 0.82; P < 0.0001). There was a moderate correlation between FEV1 , FVC and DLCO with MSWT distance (r = 0.55, r = 0.61, r = 0.61, respectively; all P < 0.001) and with peak VO2 (r = 0.62, r = 0.63, r = 0.62, respectively; all P < 0.0001). CONCLUSIONS: Peak VO2 achieved during CPET strongly correlated with MSWT distance. MSWT is a measure of peak exercise capacity in sarcoidosis that does not require equipment and can be readily available in the clinic.

The 2-Minutes Walking Test Is Not Correlated with Aerobic Fitness Indices but with the 5-Times Sit-to-Stand Test Performance in Apparently Healthy Older Adults.

The 2-minutes walking test (2-MWT) is a valid and reliable test that has a high correlation with the distance walked in the 6-minutes walking test (6-MWT). However, to date, no study has determined the relationship between 2-MWT performance and the aerobic fitness indices obtained during a maximal incremental test to confirm if this test is a valid surrogate of aerobic fitness in apparently healthy older adults. The main objective of this work was to identify the factors associated to the performance in the 2-MWT, including aerobic fitness, functional and spatial-temporal gait parameters. Seventeen elderly adults performed a maximal incremental cycling test to determine maximum oxygen consumption (VO2max) and ventilatory thresholds (VT1 and VT2), two static standing balance tests with open and close eyes, a 5-times sit-to-stand test (5-TSTS), a handgrip test, and a 2-MWT on three different days over 2 weeks. No correlations were found between aerobic fitness indices and the distance covered in 2-MWT, but significant moderate correlations were found between the distance covered in 2-MWT and the time to perform the 5-TSTS (rho = -0.49) and with stride length (rho = 0.52) during the test. In conclusion, the 2-MWT does not seem a good test to assess aerobic capacity while it showed to be associated to the 5-TSTS performance of the elderly.

Graded peak cycle ergometer test for cognitively impaired patients with Parkinson's disease: a pilot study.

BACKGROUND: Cognitive decline affects up to 50% of patients with Parkinson's disease (PD) in the course of the disease and may be amenable to exercise interventions. To accurately set adequate training intensities, standardized exercise testing is required but such testing takes considerable time and effort. The aim of this pilot study was to investigate the feasibility of a graded peak cycle ergometer exercise test in cognitively impaired patients with Parkinson's Disease (PD), and to define whether age-predicted maximal heart rate (HRmax) matched measured HRmax. METHODS: A convenience sample of seven patients with PD (Hoehn and Yahr: 2-4, and cognitive impairment (Montreal Cognitive Assessment (MoCA) ≤ 26) completed a graded peak cycle ergometer test to voluntary exhaustion. Borg Rating of Perceived Exertion was used to record the individual's perception of exertion. Pre-defined age-predicted HRmax (calculated as 208-(0.7 × age) was compared with the measured HRmax using Bland-Altman plot and a two-one-sided test. RESULTS: All PD patients completed the graded exercise test between 8-12 minutes, showing therefore 100% compliance to the test protocol. No adverse events occurred. Predicted HRmax and measured HRmax did not differ. CONCLUSION: We demonstrate feasibility of graded peak cycle ergometer testing in PD patients with cognitive impairment. The good correspondence of age-predicted HRmax equation with measured HRmax, in this small sample, may in the future provide clinicians with a tool to define training intensities in cognitively impaired PD, without cardiac disease. However, further research is needed to confirm these results.

A Sensorless Modular Multiobjective Control Algorithm for Left Ventricular Assist Devices: A Clinical Pilot Study.

Background: Contemporary Left Ventricular Assist Devices (LVADs) mainly operate at a constant speed, only insufficiently adapting to changes in patient demand. Automatic physiological speed control promises tighter integration of the LVAD into patient physiology, increasing the level of support during activity and decreasing support when it is excessive. Methods: A sensorless modular control algorithm was developed for a centrifugal LVAD (HVAD, Medtronic plc, MN, USA). It consists of a heart rate-, a pulsatility-, a suction reaction-and a supervisor module. These modules were embedded into a safe testing environment and investigated in a single-center, blinded, crossover, clinical pilot trial (clinicaltrials.gov, NCT04786236). Patients completed a protocol consisting of orthostatic changes, Valsalva maneuver and submaximal bicycle ergometry in constant speed and physiological control mode in randomized sequence. Endpoints for the study were reduction of suction burden, adequate pump speed and flowrate adaptations of the control algorithm for each protocol item and no necessity for intervention via the hardware safety systems. Results: A total of six patients (median age 53.5, 100% male) completed 13 tests in the intermediate care unit or in an outpatient setting, without necessity for intervention during control mode operation. Physiological control reduced speed and flowrate during patient rest, in sitting by a median of -75 [Interquartile Range (IQR): -137, 65] rpm and in supine position by -130 [-150, 30] rpm, thereby reducing suction burden in scenarios prone to overpumping in most tests [0 [-10, 2] Suction events/minute] in orthostatic upwards transitions and by -2 [-6, 0] Suction events/min in Valsalva maneuver. During submaximal ergometry speed was increased by 86 [31, 193] rpm compared to constant speed for a median flow increase of 0.2 [0.1, 0.8] L/min. In 3 tests speed could not be increased above constant set speed due to recurring suction and in 3 tests speed could be increased by up to 500 rpm with a pump flowrate increase of up to 0.9 L/min. Conclusion: In this pilot study, safety, short-term efficacy, and physiological responsiveness of a sensorless automated speed control system for a centrifugal LVAD was established. Long term studies are needed to show improved clinical outcomes. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT04786236.

The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise.

The accumulation of lactate in muscle and blood during high-intensity exercise is negatively correlated with the duration exercise can be sustained. Removal of lactate is a key component of acute recovery between consecutive bouts of such exercise. Low-intensity exercise enhances recovery by accelerating lactate turnover in metabolically active tissues, largely mediated by blood flow to these tissues. Therefore, the purpose of this research was to clarify if L-citrulline, a nutritional supplement purported to promote vasodilation via enhanced nitric oxide availability, would augment the removal of blood lactate during active recovery (AR). L-citrulline ingestion will augment the rate of blood lactate concentration decrease during AR, reduce the oxygen-cost of submaximal exercise, and increase time-to-exhaustion and peak oxygen uptake (V̇O2peak) during a test of maximal aerobic power. Healthy university students (five males & five females) participated in this double-blind, randomized, placebo-controlled study. Participants exercised on a cycle ergometer at submaximal steady-state intensities followed by progressively increasing intensity to exhaustion, 10 min of AR, and then supramaximal intensity exercise to exhaustion. Oxygen uptake was measured throughout the trial and blood lactate was sampled repeatedly during AR. The protocol elicited very high peak blood lactate concentrations after exercise (11.3 + 1.3 mmol/L). L-citrulline supplementation did not significantly alter blood lactate kinetics during AR, the oxygen cost of exercise, V̇O2peak, or time-to-exhaustion. Despite a strong theoretical basis by which L-citrulline could augment lactate removal from the blood, L-citrulline supplementation showed no effect as an exercise-recovery supplement.

Effectiveness of Functional Electrical Stimulation - Cycling Treatment in Children with Cerebral Palsy.

AIM: The purpose of this study was to evaluate the effects of functional electrical stimulation (FES) bicycle therapy system on motor function, gait pattern, spasticity, daily living activities, and aerobic capacity in children with cerebral palsy (CP) and to compare the results with sham stimulation and standard treatment. METHODS: Patients with cerebral palsy who received botulinum toxin type-A injections to lower extremities and those with Gross Motor Function Measure Classification System (GMFCS) levels I - III, were included in the study. Twenty-five patients were randomly assigned into three treatment groups for 4-weeks: Group 1, FES-cycling and standard treatment; Group 2, Sham stimulus FES-cycling and standard treatment; Group 3, Standard treatment. Clinical assessment tools included the Modified Ashworth Scale (MAS), Modified Tardieu Scale (MTS), Pediatric Functional Independence Measure (WeeFIM), GMFCS, Gross Motor Function Measure-88 (GMFM-88), selective motor control tests, 6-minute walk test, and Visual Gait Analysis (VGA). RESULTS: In all groups, there were significant improvements in MAS, MTS, WeeFIM, GMFM-88, 6-minute walk test, and VGA scores. No changes in GMFCS levels were observed in any group. At the end of the study, there was no significant difference among the groups in terms of any clinical assessment parameter. CONCLUSIONS: All groups showed statistically significant improvements in motor function, walking pattern, spasticity, daily living activities, and aerobic capacity in patients with CP following the rehabilitation period. Although FES-cycling demonstrated no superiority over the other approaches and provided no additional benefit to the results, FES appears to be safe and well-tolerated in children with CP, at least as much as standard exercise treatment.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population.

BACKGROUND: Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V?O2) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women. METHODS: 182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V?O2) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced. RESULTS: Height, sex and age resulted predictive of both V?O2 peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V?O2peak=0.017·height?(cm)-0.023·age?(years)+0.864·sex?(female=0/male=1)±179?l?min-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony. CONCLUSIONS: This study provides new and accurate V?O2 peak and WR rate reference values for individuals of European Spanish descent.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population.

BACKGROUND: Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V˙O2) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women. METHODS: 182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V˙O2) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced. RESULTS: Height, sex and age resulted predictive of both V˙O2 peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V˙O2peak=0.017⋅height(cm)-0.023⋅age(years)+0.864⋅sex(female=0/male=1)±179lmin-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony. CONCLUSIONS: This study provides new and accurate V˙O2 peak and WR rate reference values for individuals of European Spanish descent.

Cardiopulmonary Exercise Testing and Surgery.

The surgical patient population is increasingly elderly and comorbid and poses challenges to perioperative physicians. Accurate preoperative risk stratification is important to direct perioperative care. Reduced aerobic fitness is associated with increased postoperative morbidity and mortality. Cardiopulmonary exercise testing is an integrated and dynamic test that gives an objective measure of aerobic fitness or functional capacity and identifies the cause of exercise intolerance. Cardiopulmonary exercise testing provides an individualized estimate of patient risk that can be used to predict postoperative morbidity and mortality. This technology can therefore be used to inform collaborative decision-making and patient consent, to triage the patient to an appropriate perioperative care environment, to diagnose unexpected comorbidity, to optimize medical comorbidities preoperatively, and to direct individualized preoperative exercise programs. Functional capacity, evaluated as the anaerobic threshold and peak oxygen uptake ([Formula: see text]o2peak) predicts postoperative morbidity and mortality in the majority of surgical cohort studies. The ventilatory equivalents for carbon dioxide (an index of gas exchange efficiency), is predictive of surgical outcome in some cohorts. Prospective cohort studies are needed to improve the precision of risk estimates for different patient groups and to clarify the best combination of variables to predict outcome. Early data suggest that preoperative exercise training improves fitness, reduces the debilitating effects of neoadjuvant chemotherapy, and may improve clinical outcomes. Further research is required to identify the most effective type of training and the minimum duration required for a positive effect.

Diagnostic value of ST-segment deviations during cardiac exercise stress testing: Systematic comparison of different ECG leads and time-points.

BACKGROUND: Exercise ECG stress testing is the most widely available method for evaluation of patients with suspected myocardial ischemia. Its major limitation is the relatively poor accuracy of ST-segment changes regarding ischemia detection. Little is known about the optimal method to assess ST-deviations. METHODS: A total of 1558 consecutive patients undergoing bicycle exercise stress myocardial perfusion imaging (MPI) were enrolled. Presence of inducible myocardial ischemia was adjudicated using MPI results. The diagnostic value of ST-deviations for detection of exercise-induced myocardial ischemia was systematically analyzed 1) for each individual lead, 2) at three different intervals after the J-point (J+40ms, J+60ms, J+80ms), and 3) at different time points during the test (baseline, maximal workload, 2min into recovery). RESULTS: Exercise-induced ischemia was detected in 481 (31%) patients. The diagnostic accuracy of ST-deviations was highest at +80ms after the J-point, and at 2min into recovery. At this point, ST-amplitude showed an AUC of 0.63 (95% CI 0.59-0.66) for the best-performing lead I. The combination of ST-amplitude and ST-slope in lead I did not increase the AUC. Lead I reached a sensitivity of 37% and a specificity of 83%, with similar sensitivity to manual ECG analysis (34%, p=0.31) but lower specificity (90%, p<0.001). CONCLUSION: When using ECG stress testing for evaluation of patients with suspected myocardial ischemia, the diagnostic accuracy of ST-deviations is highest when evaluated at +80ms after the J-point, and at 2min into recovery.

Acute effects of lateral shoe wedges on joint biomechanics of patients with medial compartment knee osteoarthritis during stationary cycling.

Cycling is commonly prescribed for individuals with knee osteoarthritis (OA) but very little biomechanical research exists on the topic. Individuals with OA may be at greater risk of OA progression or other knee injuries because of their altered knee kinematics. This study investigated the effects of lateral wedges on knee joint biomechanics and pain in patients with medial compartment knee OA during stationary cycling. Thirteen participants with OA and 11 paired healthy participants volunteered for this study. A motion analysis system and a customized instrumented pedal were used to collect 5 pedal cycles of kinematics and kinetics, respectively, during 2 minutes of cycling in 1 neutral and 2 lateral wedge (5° and 10°) conditions. Participants pedaled at 60 RPM and an 80W workrate and rated their knee pain on a visual analog scale during each minute of each condition. There was a 22% decrease in the internal knee abduction moment with the 10° wedge. However, this finding was not accompanied by a decrease in knee adduction angle or subjective pain. Additionally, there was an increase in vertical and horizontal pedal reaction force which may negate the advantages of the decreased internal knee abduction moment. For people with medial knee OA, cycling with 10° lateral wedges may not be sufficient to slow the progression of OA beyond the neutral riding condition.

Foot orthoses do not affect crank power output during maximal exercise on a cycle-ergometer.

OBJECTIVES: To investigate the effects of custom-made foot orthoses on the torque- and power-cadence relationships and perceived comfort during maximal cycling exercises in a population of competitive road cyclists. DESIGN: Randomised, repeated measures, participant-blinded controlled study. METHODS: Twenty-four competitive road cyclists (22 males, 2 females; aged 18-53 years) with mobile feet performed the torque-velocity test with custom-made and sham foot orthoses. For both conditions, the maximal power, optimal cadence, optimal torque, maximal torque, and maximal cadence were extracted from the individual torque- and power-cadence relationships. Comfort was assessed on a 150mm visual analogue scale. Paired-samples t-tests were used for comparison of means between conditions. RESULTS: No differences were observed between the custom-made and sham foot orthoses for any of the key variables extracted: maximal power (1022±180 vs. 1020±172W; p=0.794), optimal cadence (118±10 vs. 119±9rpm; p=0.682), optimal torque (82±10 vs. 82±11Nm; p=0.559), maximal torque (157±23 vs. 159±20 Nm; p=0.665) and maximal cadence (220±22 vs. 221±20rpm; p=0.935). There was no difference in comfort between custom-made and sham foot orthoses (106±30.5 vs. 116±25.0mm; p=0.995). CONCLUSIONS: Compared to the sham foot orthoses, the custom-made foot orthoses did not significantly affect the torque and power generating capacities or comfort during a maximal exercise performed on a stationary cycle ergometer.

Muscle Metabolic Responses During Dynamic In-Magnet Exercise Testing: A Pilot Study in Children with an Idiopathic Inflammatory Myopathy.

RATIONALE AND OBJECTIVES: The clinical utility of supine in-magnet bicycling in combination with phosphorus magnetic resonance spectroscopy ((31)P MRS) to evaluate quadriceps muscle metabolism was examined in four children with juvenile dermatomyositis (JDM) in remission and healthy age- and gender-matched controls. MATERIALS AND METHODS: Two identical maximal supine bicycling tests were performed using a magnetic resonance-compatible ergometer. During the first test, cardiopulmonary performance was established in the exercise laboratory. During the second test, quadriceps energy balance and acid/base balance during incremental exercise and phosphocreatine recovery were determined using (31)P MRS. RESULTS: During the first test, no significant differences were found between patients with JDM and their healthy peers regarding cardiopulmonary performance. The outcomes of the first test indicate that both groups attained maximal performance. During the second test, quadriceps phosphocreatine and pH time courses were similar in all but one patient experiencing idiopathic postexercise pain. This patient demonstrated faster phosphocreatine depletion and acidification during exercise, yet postexercise mitochondrial adenosine triphosphate synthesis rate measured by phosphocreatine recovery kinetics was approximately twofold faster than control (time constant 23 seconds vs 43 ± 7 seconds, respectively). CONCLUSIONS: These results highlight the utility of in-magnet cycle ergometry in combination with (31)P MRS to assess and monitor muscle energetic patterns in pediatric patients with inflammatory myopathies.

The influence of physical strain on esophageal motility in healthy volunteers studied with gas-perfusion manometry.

BACKGROUND: The influence of physical strain on the esophageal motility has already been examined in a number of studies. It was found that high physical strain compromises the sufficient contractility of the esophagus. However, it needs more examinations to verify these findings. METHODS: To validate these results healthy volunteers were examined using gas-perfusion manometrie. Bicycle ergometry was performed to generate an exactly defined physical exercise. After a pilot study, the changing of the contraction amplitude was determined as the main variable to evaluate the esophageal motility, and the sample size was calculated. Eight subjects without esophageal diseases or symptoms were examined by simultaneous gas-perfusion esophageal manometry and bicycle ergometry. KEY RESULTS: The results showed that high physical strain during bicycle ergometry can induce a significant decrease of the contraction amplitude (α = 5%, ß = 10%). The 95% confidence interval of the quotient of contraction amplitude at rest and under physical strain is (1.074; 1.576). This effect is more pronounced in liquid acts of swallowing than in dry and is also more obvious at the middle measuring point (7.8 cm above the lower esophageal sphincter) than at the distal and proximal point (2.8 and 12.8 cm). Furthermore, a decreasing tendency of the contraction duration could be found. CONCLUSIONS & INTERFERENCES: Gas-perfusion manometry is an inexpensive examination method, which enables the evaluation of the esophageal motility in moving test subjects under conditions of physical strain. It could be proved that physical strain negatively influences the esophageal motility by a decrease of the contraction amplitude.

The effect of passive versus active recovery on power output over six repeated wingate sprints.

PURPOSE: The aim of this study was to examine the effect of active versus passive recovery on 6 repeated Wingate tests (30-s all-out cycling sprints on a Velotron ergometer). METHOD: Fifteen healthy participants aged 29 (SD = 8) years old (body mass index = 23 [3] kg/m(2)) participated in 3 sprint interval training sessions separated by 3 to 7 days between each session during a period of 1 month. The 1st visit was familiarization to 6 cycling sprints; the 2nd and 3rd visits involved a warm-up followed by 6 30-s cycling sprints. Each sprint was followed by 4 min of passive (resting still on the ergometer) or active recovery (pedaling at 1.1 W/kg). The same recovery was used within each visit, and recovery type was randomized between visits. RESULTS: Active recovery resulted in a 0.6 W/kg lower peak power output in the second sprint (95% confidence interval [CI] [ - 0.2, - 0.8 W/kg], effect size = 0.50, p < .01) and a 0.4 W/kg greater average power output in the 5th and 6th sprints (95% CI [+0.2,+0.6 W/kg], effect size = 0.50, p < .01) compared with passive recovery. There was little difference between fatigue index, total work, or accumulated work between the 2 recovery conditions. CONCLUSIONS: Passive recovery is beneficial when only 2 sprints are completed, whereas active recovery better maintains average power output compared with passive recovery when several sprints are performed sequentially (partial eta squared between conditions for multiple sprints = .38).