Portable Gas Analysis System Research Articles

The Analysis of the Effects of Interval Training Program on Aerobic and Anaerobic Performance in Slalom and Giant Slalom Athletes

The purpose of this study is to analyze the effects of interval training on the aerobic and anaerobic performance of elite-level athletes in slalom and giant slalom disciplines. The study consisted of thirteen male athletes in the alpine skiing discipline (slalom-giant slalom). The heights of the athletes were measured with a stadiometer with a precision of ±1mm (Holtain, UK). Weight measurements were conducted using a Tanita brand body composition analyzer (BC, 418 Tanita, Japan) with a precision of 100 grams. For aerobic power and capacity testing, a breath-by-breath measurement method was employed using the Cosmed K5 portable gas analysis system (Italy). The MaxVO2 protocol was performed on a cycle ergometer, and the anaerobic power and capacity test were conducted using the Wingate method. Aerobic/anaerobic power values of athletes were measured twice, before and after a 4-week interval training program. An Independent Samples T-Test was used to identify differences between pre-test and post-test values of athletes. Significant relationships were found between pre-test and post-test values of MaxVO2, peak power, average power, and power drop percentage for slalom and giant slalom athletes subjected to interval training (p0.05). In conclusion, interval training was observed to increase body muscle mass, reduce body fat percentage, and enhance aerobic and anaerobic capacity in slalom and giant slalom athletes. Including interval training in the content of athletes' training programs when creating annual training plans is considered to positively influence aerobic and anaerobic performance using the interval training method.

Analysis of the performance of the portable Cortex Metamax 3B gas analysis system in simulated and real workouts with Vietnamese teenagers

The aim of this study was to investigate the performance of the mobile Cortex Metamax 3B (MM3B) automated gas meter in simulated and real workouts involving teenagers. A total of 28 healthy volunteers (13 men, 15 female) were selected with the following characteristics (mean ± SD): age 17.2 ± 3.1; height 167.1 ± 13.5 cm; weight 54.6 ± 10.4 kg. The following equipment were used: Hypermax 3B (breath-by-breath breathing system), Validator for Gas Exchange Systems (VGES), and Douglas-bag technique (DBT). The results have shown that MM3B is stable at the permitted range during 3 hours while monitoring the gas fractions, as well as the VE, VO2, and VCO2 created by GESV, especially at moderate and high metabolic rates (2% deviation and modest physiological significance). MM3B rated both VO2 and VCO2 significantly higher by about 10-17% at moderate and strenuous activity than DBM and at all exercise levels than Oxycon Pro, although without a significant margin of error in VE. Between the two criteria systems, none of the metabolic variables showed any discernible change (DBM and Oxycon Pro). The MM3B provided acceptable data on stability and reliability, but it was decided that without further adjustment for VO2 and VCO2, the data were not valid during moderate and strenuous activity.

Effects Of Pyruvate On Aerobic Energy Contribution And Lactate Acidosis Of High-intensity Interval Exercise

Maintain a stable acid-base balance is essential for exercise performance. Pyruvate has obvious benefits to attenuate acidosis. However, the role of pyruvate on acid-base buffer during high-intensity interval exercise (HIIE) remains unclear. PURPOSE: Assess the role of pyruvate on HIIE induced lactate acidosis from the perspective of energy metabolism. METHODS: In this double-blind, randomized, crossover trial, 14 male college football players (age: 20 ± 2 yrs; body fat: 13.11 ± 3.50%) were determined maximal aerobic power output using progressive ergometer cycle test. After one week of wash out period, they supplied sodium pyruvate or placebo (0.1 g/kg/d) for 7 days. Sixty minutes after the last ingestion, resting oxygen consumption rate was collected. Then, subjects performed HIIE (4*1 min 110% VO2max, interval 1 min rest) to induce lactate acidosis. Venous and fingertip blood samples were collected for blood gas and lactate analysis. A portable Cortex Metamax 3B gas analysis system was used to measure oxygen consumption. Aerobic energy or ATP-PCr energy contribution: resting oxygen consumption was subtracted from the oxygen consumption obtained during each 110% VO2max or 1-min resting bout. Lactate difference before and after each 110% VO2max bout assumed to calculate glycolytic energy contribution. 1 mM of lactate corresponds to 3 ml of oxygen/kg of body mass. 1 L of oxygen corresponds to 20.92 kJ. RESULTS: Aerobic energy contribution of fourth 110% VO2max bout was significantly improved in pyruvate than placebo group (59.14 ± 7.07 kJ vs. 50.26 ± 10.72 kJ, p < 0.05). ATP-PCr and glycolytic energy contribution were not obviously changed. Blood pH (7.40 ± 0.03 vs. 7.37 ± 0.03, p < 0.01 ), HCO3- (26.09 ± 0.82 vs. 24.86 ± 1.03, p < 0.01), BE (3.39 ± 0.86 vs. 2.06 ± 0.41, p < 0.01) before HIIE and Blood pH (7.20 ± 0.05 vs. 7.14 ± 0.08, p < 0.05 ), HCO3- (14.56 ± 1.83 vs. 12.94 ± 2.25, p < 0.05) , BE (-12.79 ± 3.22 vs. -15.61 ± 4.39, p < 0.05) after HIIE in pyruvate group were significant higher than placebo group. CONCLUSIONS: The finding suggests that pyruvate supplementation can improve HIIE-induced lactate acidosis and aerobic energy contribution, which might indicate that pyruvate buffers HIIE-induced lactate acidosis by improving aerobic oxidation capacity.

Relationship Between Running Economy and Kinematic Parameters in Long-Distance Runners.

Pizzuto, F, Fonseca de Oliveira, C, Amorim Soares, TS, Rago, V, Silva, G, and Oliveira, J. Relationship between running economy and kinematic parameters in long-distance runners. J Strength Cond Res 33(7): 1921-1928, 2019-The purpose of this study was to explore the relationship between running economy (RE) and sagittal, frontal, and transverse plane kinematic parameters in long-distance runners. A secondary purpose was to identify the kinematic predictors of RE during running at the lowest RE value, representing an individual's most efficient running intensity. Twenty recreational long-distance runners ran 3 submaximal stages on a treadmill (65, 75, and 85% of velocity at maximum oxygen consumption). Respiratory data were collected using a portable gas analysis system. Kinematics were gathered using passive retroreflective markers and 8 high-resolution infrared cameras to collect the respective trajectories. Hip, knee, and ankle angles at foot strike and stance phase, as well as spatio-temporal parameters were calculated during each gait cycle. Knee flexion/extension range of motion (ROM), knee ab/adduction ROM, and hip ab/adduction ROM during the stance phase of the gait cycle showed positive moderate to large correlations with RE (r ± 90% confidence intervals = 0.51 ± 0.29; 0.49 ± 0.30; 0.53 ± 0.28, respectively). Knee and hip ab/adduction ROMs during the stance phase are predictors of RE, accounting for 44% of RE variance. Therefore, sagittal and frontal plane kinematics affect RE-inducing alterations in running performance. Coaches, athletic trainers, and anyone involved in running training prescription should consider a relationship between these parameters to ensure optimal technique and, consequently, to improve RE in recreational long-distance runners.

Sitting to standing postural changes: Energy expenditure and a possible mechanism to alleviate sedentary behavior.

Background and aims Sedentary lifestyles have recently been identified as potential mechanism for obesity and associated metabolic diseases linked to ill health. The aim of this study was to investigate the effects of standing and sitting-standing positional changes on energy cost and consequently interrupting sedentary sitting time while working. Methods A total of 26 healthy male volunteers performed normal typing and editing work for 100min under three conditions. The conditions included sustained sitting, sustained standing, and sitting-standing alternation every 20min using a sit-stand desk. Respiratory parameters measured included minute ventilation (VE), oxygen consumption (VO2), and energy expenditure (EE). Measurements were recorded using a calibrated Cosmed K4b2 portable gas analysis system. Results The mean value for VE was the highest in the standing position (VE = 13.33 ± 0.71), followed by sitting-standing alternation (VE = 12.04 ± 0.62). Both were significantly different from sitting (VE = 10.59 ± 0.69). The maximum VE and EE for standing (VE = 14.81 ± 0.43 and EE = 1.84 ± 0.10) and sitting-standing alternation (VE = 14.80 ± 0.40 and EE = 1.93 ± 0.08) were significantly higher than that of sitting (VE = 12.15 ± 0.42 and EE = 1.67 ± 0.07). No significant differences were observed in the mean VO2 among the three conditions. However, the maximum VO2 for both standing (VO2 = 5.40 ± 0.20) and sitting-standing alternation (VO2 = 5.14 ± 0.17) had shown to be significantly higher than sitting (VO2 = 4.50 ± 0.18). There were no significant differences observed in the mean EE levels between sitting (EE = 1.43 ± 0.07) and sitting-standing alternation (EE = 1.55 ± 0.08). However, the mean EE while standing (EE = 1.62 ± 0.09) significantly increased compared to sitting. Conclusions The findings of this study indicate that sitting-standing alternations may be implemented as an effective intervention to interrupt prolonged sitting while working.

Reliability of the Portable Metabolic Gas Analysis System used on the International Space Station

Metabolic gas analysis is utilized for both research and medical operations purposes on the International Space Station (ISS). Data regarding reliability of metabolic gas analysis system used on board the ISS, the Portable Pulmonary Function System (PPFS – Danish Aerospace Corporation, Odense, DK), has not been reported. PURPOSE: To determine the reliability and intra-subject repeatability of metabolic gas analysis data collected by the PPFS. METHODS: Subjects (n=8: 5M, 3F) performed 3 peak cycle tests, consisting of three 5-min stages designed to elicit 25%, 50%, and 75% peak oxygen consumption (VO2peak) followed by stepwise increases of 25 W/min until reaching volitional exhaustion. Metabolic gas analysis was performed using the PPFS during these tests. Intraclass correlation coefficients (ICC), within-subject standard deviations (WS SD), and coefficients of variation (CV %) were calculated. RESULTS: The ICC, WS SD and CV % for peak exercise are contained in the table below. Across all exercise stages, the ICC values for oxygen consumption (VO2), carbon dioxide production (VCO2), and ventilation (VE) ranged from 0.79 to 0.99; however, the ICC for respiratory exchange ratio (RER) indicated poorer agreement between trials (ICC=0.11 to 0.51). The CV values for all dependent variables ranged from 2.6% to 6.6%, which are consistent with reported values obtained using other metabolic gas analysis devices.Table: No title available.CONCLUSIONS: The PPFS appears to yield reliable metabolic gas analysis data. Lower reliability of RER measurements are reported in the literature using other devices and is not likely a function of the PPFS. The PPFS should provide accurate and reliable data for research and monitoring of human adaptation to spaceflight.

Inflammatory biomarkers responses after acute whole body vibration in fibromyalgia.

The aims of this study were 1) to characterize the intensity of the vibration stimulation in women diagnosed with fibromyalgia (FM) compared to a control group of healthy women (HW) matched by age and anthropometric parameters, and 2) to investigate the effect of a single session of whole body vibration (WBV) on inflammatory responses. Levels of adipokines, soluble tumor necrosis factor receptors (sTNFr1, sTNFr2), and brain-derived neurotrophic factor (BDNF) were determined by enzyme-linked immunosorbent assay. Oxygen consumption (VO2) was estimated by a portable gas analysis system, heart rate (HR) was measured using a HR monitor, and perceived exertion (RPE) was evaluated using the Borg scale of perceived exertion. Acutely mild WBV increased VO2 and HR similarly in both groups. There was an interaction (disease vs vibration) in RPE (P=0.0078), showing a higher RPE in FM compared to HW at rest, which further increased in FM after acute WBV, whereas it remained unchanged in HW. In addition, there was an interaction (disease vs vibration) in plasma levels of adiponectin (P=0.0001), sTNFR1 (P=0.000001), sTNFR2 (P=0.0052), leptin (P=0.0007), resistin (P=0.0166), and BDNF (P=0.0179). In conclusion, a single acute session of mild and short WBV can improve the inflammatory status in patients with FM, reaching values close to those of matched HW at their basal status. The neuroendocrine mechanism seems to be an exercise-induced modulation towards greater adaptation to stress response in these patients.

Open-circuit respirometry: a historical review of portable gas analysis systems.

Scientists such as physiologists, engineers, and nutritionists have often sought to estimate human metabolic strain during daily activities and physical pursuits. The measurement of human metabolism can involve direct calorimetry as well as indirect calorimetry using both closed-circuit respirometry and open-circuit methods that can include diluted flow chambers and laboratory-based gas analysis systems. For field studies, methods involving questionnaires, pedometry, accelerometery, heart rate telemetry, and doubly labelled water exist, yet portable metabolic gas analysis remains the gold standard for most field studies on energy expenditure. This review focuses on research-based portable systems designed to estimate metabolic rate typically under steady-state conditions by critically examining each significant historical innovation. Key developments include Zuntz's 1906 innovative system, then a significant improvement to this purely mechanical system by the widely adopted Kofranyi-Michaelis device in the 1940s. Later, a series of technical improvements: in electronics lead to Wolf's Integrating Motor Pneumotachograph in the 1950s; in polarographic O2 cells in 1970-1980's allowed on-line oxygen uptake measures; in CO2 cells in 1990s allowed on-line respiratory exchange ratio determination; and in advanced sensors/computing power at the turn of the century led to the first truly breath-by-breath portable systems. Very recent significant updates to the popular Cosmed and Cortex systems and the potential commercial release of the NASA-developed 'PUMA' system show that technological developments in this niche area are still incrementally advancing.

The Effects of Squats and Jump Squats on Mechanical Work and Energy Expenditure

PURPOSE: To investigate the effects of two non-ballistic squat and two ballistic jump squat protocols performed over multiple sets on the total mechanical work performed and oxygen uptake. METHODS: In a counterbalanced cross-over design, 11 resistance-trained men (age: 21.9 ± 1.8 years; height: 1.79 ± 0.05 m; mass: 87.0 ± 7.4 kg) attended four testing sessions during a three week period where they performed multiple sets of squats and jump squats with a load equivalent to 30% 1-repeititon maximum under one of the following conditions: 1) three sets of four non-ballistic repetitions (30N-B), 2) three sets of four non-ballistic repetitions with a 3-second pause between the eccentric and concentric phases (30PN-B), 3) three sets of four ballistic repetitions (30B), 4) three sets of four ballistic repetitions with a 3-second pause between the eccentric and concentric phases (30PB). Force plates and a 3-D motion analysis system were used to determine the total mechanical work performed during each session while a portable gas analysis system was used to collect expired gases. RESULTS: Total mechanical work performed during each set was significantly greater during 30B compared to 30N-B (mean difference [MD]: 7,792 J, p<0.001, effect size [ES]: 1.88) and 30PN-B (MD: 7,749 J, p<0.001, ES: 1.89), while that during 30PB was significantly greater than that during both 30N-B (MD: 7,488 J, p<0.001, ES: 1.89) and 30PN-B (MD: 7,445 J, p<0.001, ES: 1.90). Energy expenditure during each set was significantly greater during the 30B condition compared to the 30N-B (MD: 13,983 J, p<0.001, ES: 1.08) and the 30PN-B (MD: 11,326 J, p=0.001, ES: 0.92). Energy expenditure during 30PB was also significantly greater than that during 30N-B (MD: 12,615 J, p=0.001, ES: 1.04) and 30PN-B (MD: 9,958 J, p=0.006, ES: 0.86). Furthermore, energy expenditure during set 1 was significantly greater than that during set 2 (MD: 6,840 J, p<0.001, ES: 0.64) and set 3 (MD: 8,070 J, p<0.001, ES: 0.75). CONCLUSION: Ballistic resistance training exercises may represent a more effective metabolic stimulus compared to traditional resistance training exercises and a pause inserted between the eccentric and concentric phases has little effect.

A biologically-inspired multi-joint soft exosuit that can reduce the energy cost of loaded walking.

BackgroundCarrying load alters normal walking, imposes additional stress to the musculoskeletal system, and results in an increase in energy consumption and a consequent earlier onset of fatigue. This phenomenon is largely due to increased work requirements in lower extremity joints, in turn requiring higher muscle activation. The aim of this work was to assess the biomechanical and physiological effects of a multi-joint soft exosuit that applies assistive torques to the biological hip and ankle joints during loaded walking.MethodsThe exosuit was evaluated under three conditions: powered (EXO_ON), unpowered (EXO_OFF) and unpowered removing the equivalent mass of the device (EXO_OFF_EMR). Seven participants walked on an instrumented split-belt treadmill and carried a load equivalent to 30 % their body mass. We assessed their metabolic cost of walking, kinetics, kinematics, and lower limb muscle activation using a portable gas analysis system, motion capture system, and surface electromyography.ResultsOur results showed that the exosuit could deliver controlled forces to a wearer. Net metabolic power in the EXO_ON condition (7.5 ± 0.6 W kg−1) was 7.3 ± 5.0 % and 14.2 ± 6.1 % lower than in the EXO_OFF_EMR condition (7.9 ± 0.8 W kg−1; p = 0.027) and in the EXO_OFF condition (8.5 ± 0.9 W kg−1; p = 0.005), respectively. The exosuit also reduced the total joint positive biological work (sum of hip, knee and ankle) when comparing the EXO_ON condition (1.06 ± 0.16 J kg−1) with respect to the EXO_OFF condition (1.28 ± 0.26 J kg−1; p = 0.020) and to the EXO_OFF_EMR condition (1.22 ± 0.21 J kg−1; p = 0.007).ConclusionsThe results of the present work demonstrate for the first time that a soft wearable robot can improve walking economy. These findings pave the way for future assistive devices that may enhance or restore gait in other applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-016-0150-9) contains supplementary material, which is available to authorized users.

Energy consumption character due to different forward position change during jogging movement

This paper is designed to examine the changes of energy consumption under different forward position change through heel height wearing during jogging. 14 healthy females took part in this study with flat shoe (1.2 cm), low-heeled shoe (4.5 cm) and high-heeled shoe (7 cm), respectively. Energy consumption data were collected by K4b2 portable gas analysis system during jogging. The results of this study showed that minute ventilation (VE), relative oxygen consumption (VO2) and energy cost (EE) significantly rose with the increase of heel height, and increased rapidly with high and low heels during the last minutes of jogging. Our research showed it easily causes neuromuscular fatigue when jogging with high heels, so people could slow down the speed.

Clinical significance of measuring resting energy expenditure for guiding an accurate nutritional support in elderly bedridden patients with nasal feeding

Objective To investigate the clinical significance of measuring resting energy expenditure (REE) for guiding an accurate nutritional support in elderly bedridden patients with nasal feeding. Methods The REE of 32 elderly bedridden patients with nasal feeding was assessed by using the Cosmed K4b2 portable telemetric gas analysis system. The waist-hip ratio, serum levels of albumin, transferrin, prealbumin and retinol-binding protein were determined to assess comprehensive nutrition status. The energy intakes were calculated, and the correlation of REE and the difference between the energy intakes and consumption with nutritional index were analyzed. Results The resting energy expendture was lower in the patients with waist-hip ratio≥0.95 than in patients with waist-hip ratio <0.95 (t=3.622, P<0.01). The waist-hip ratio was reduced and serum albumin and transferrin levels were decreased along with the increase of REE in elderly patients (r=-0.55, -0.36 and -0.593, respectively, P=0.001, 0.043, <0.001). The difference between the energy intake and expenditure was higher in patients with waist-hip ratio≥0.95 than those with waist-hip ratio<0.95 (t=5.643, P<0.001). Serum albumin, prealbumin, transferrin and retinol-binding protein levels were increased along with the increase of the difference between the energy intake and expenditure, which showed the positive correlations (r=0.525, 0.409, 0.624, 0.414, respectively, P=0.002, 0.02, <0.001, 0.019). Conclusions Precise determination of REE and energy intake guided by REE are the important guarantees for the reasonable nutrition support in the elderly. Key words: Energy metabolism; Intubation, nasogastric; Nutrition therapy

Diel patterns of fine root respiration in a dryland shrub, measured in situ over different phenological stages

Fine root (<2 mm) respiration (Rfr) may play an important role in carbon cycles in drylands; thus Rfr in desert ecosystems may have important implications for belowground processes and global carbon cycles. This study aimed to (1) investigate the diel and seasonal changes in Rfr of a shrub (Caragana microphylla Lam.) in situ during the growing season and to (2) detect the relationship between both photosynthesis and phenology and Rfr. The study was conducted in an even-aged C. microphylla plantation in a semiarid area in the Mu Us Desert of China. Rates of Rfr and net photosynthesis were measured using a standard chamber equipped with a portable gas analysis system. The data revealed two diel patterns that varied with different phenological stages. Diurnal Rfr rates were 2.2-fold greater than nocturnal Rfr rates. Our results showed that diurnal changes in Rfr strongly correlated with rates of net photosynthesis, suggesting that the diel changes were strongly associated with the current supply of photosynthates. Furthermore, aboveground phenology could partially explain some of the variations in seasonal Rfr. Our results provide basic information on the link between Rfr and aboveground activities, and enhance our understanding of carbon processes in dryland ecosystems.

Laboratory- and Field-Based Assessment of Maximal Aerobic Power of Elite Stand-Up Paddle-Board Athletes.

Stand-up paddle boarding (SUP) is a rapidly growing sport and recreational activity for which only anecdotal evidence exists on its proposed health, fitness, and injury-rehabilitation benefits. 10 internationally and nationally ranked elite SUP athletes. Participants were assessed for their maximal aerobic power on an ergometer in a laboratory and compared with other water-based athletes. Field-based assessments were subsequently performed using a portable gas-analysis system, and a correlation between the 2 measures was performed. Maximal aerobic power (relative) was significantly higher (P = .037) when measured in the field with a portable gas-analysis system (45.48 ± 6.96 mL · kg(-1) · min(-1)) than with laboratory-based metabolic-cart measurements (43.20 ± 6.67 mL · kg(-1) · min(-1)). There was a strong, positive correlation (r = .907) between laboratory and field maximal aerobic power results. Significantly higher (P = .000) measures of SUP paddling speed were found in the field than with the laboratory ergometer (+42.39%). There were no significant differences in maximal heart rate between the laboratory and field settings (P = .576). The results demonstrate the maximal aerobic power representative of internationally and nationally ranked SUP athletes and show that SUP athletes can be assessed for maximal aerobic power in the laboratory with high correlation to field-based measures. The field-based portable gas-analysis unit has a tendency to consistently measure higher oxygen consumption. Elite SUP athletes display aerobic power outputs similar to those of other upper-limb-dominant elite water-based athletes (surfing, dragon-boat racing, and canoeing).

Dynamic hyperinflation and dyspnea during the 6-minute walk test in stable chronic obstructive pulmonary disease patients

The purpose of this study was to investigate the relationship between dynamic hyperinflation and dyspnea and to clarify the characteristics of dyspnea during the 6-minute walk test (6MWT) in chronic obstructive pulmonary disease patients. Twenty-three subjects with stable moderate chronic obstructive pulmonary disease (age 73.8±5.8 years, all male) took part in this study. During the 6MWT, ventilatory and gas exchange parameters were measured using a portable respiratory gas analysis system. Dyspnea and oxygen saturation were recorded at the end of every 2 minute period during the test. There was a significant decrease in inspiratory capacity during the 6MWT. This suggested that dynamic hyperinflation had occurred. Dyspnea showed a significant linear increase, and there was a significant negative correlation with inspiratory capacity. It was suggested that one of the reasons that dyspnea developed during the 6MWT was the dynamic hyperinflation. Even though the tidal volume increased little after 2 minutes, dyspnea increased linearly to the end of the 6MWT. These results suggest that the mechanisms generating dyspnea during the 6MWT were the sense of respiratory effort at an early stage and then the mismatch between central motor command output and respiratory system movement.

Stationary roller versus velodrome for maximal cycling test: a comparison

Brito, J., Lopes, L., Conceicao, A., Costa A.M. & Louro, H. (2014). Wheelchair Stationary roller versus velodrome for maximal cycling test: a comparison. J. Hum. Sport Exerc., 9(1), pp.7-16. The present study aimed to compare the acute cardio-respiratory responses of elite cyclists to a maximal progressive exercise carried out in two different conditions: in a laboratory (using a braked roller) and in an uncovered velodrome. In both testing conditions, ten elite male cyclists (age, 22.3 ± 3.9 years) performed a maximal discontinuous progressive test of 6 minutes per level with 150 W of initial load and increasing 50 W at each level until exhaustion. The heart rate and the ventilation parameters were measured breath-by-breath using a portable metabolic cart gas analysis system with telemetry data transmission. In the first 4 levels of effort, no significant differences were found between the two test conditions regarding VO2, (p=0.193), heart rate (p=0.973) and pedaling cadence (p=0.116). Comparing the maximum values achieved by each athlete in both exercise conditions, significant differences were found for heart rate (p=0.008) and pedaling cadence (p=0.005) but not for VO2max and peak power. Each variable showed a strong correlation between both assessments (VO2, r=0.984, p=0,000; heart rate, r=0.944, p=0.005; pedaling cadence, r=0.900, p=0.014). The amount of variability explained by the linear regression model for both cardio-respiratory parameters also showed a good fit value close to one (VO2max, r2=0.968; heart rate, r2=0.892). Our results suggest that identical cycling protocols conducted in different testing conditions with the same bike leads to

Energy cost of walking in children with spastic cerebral palsy: Relationship with age, body composition and mobility capacity

The energy cost (EC) of walking is different for typically developing (TD) and children with cerebral palsy (CP). The associated factors of EC are not fully understood in children with CP. We assessed the relationship between EC and age, body surface area (BSA), and gross motor function measure (GMFM). We retrospectively examined data collected between 2003 and 2011 on 276 children aged 4–18 years who were classified as Gross Motor Function Classification System level I, n=79; II, n=123; and III, n=74. Energy cost was assessed while children walked 6–8min at a comfortable, self-selected speed using their typical walking aids and/or orthoses as part of a clinical gait analysis. During the test, participants wore a breath-by-breath portable gas analysis system, measuring oxygen consumption. To calculate EC (J/kg/m), oxygen consumption was converted to J/kg/min and divided by walking speed. Data were analyzed using linear regression model. Energy cost correlated inversely with age (β=−0.16, R2=0.02, P=0.01), BSA (β=−3.35, R2=0.11, P<0.0001), and GMFM (β=−0.12, R2=0.42, P<0.0001). In the multiple linear regression model, GMFM was the most potent correlate of EC, BSA explained another 10% of the variance (R2=0.53), and age was a marginally significant correlate of EC (P=0.08). In summary, in children with CP in our study, EC decreased as GMFM and BSA increased, and GMFM was the most potent correlate of EC.

The energy demands of portable gas analysis system carriage during walking and running

The aim of this study was to evaluate the carriage of a portable gas analyser during prolonged treadmill exercise at a variety of speeds. Ten male participants completed six trials at different speeds (4, 8 and 12 km h− 1) for 40 min whilst wearing the analyser (P) or where the analyser was externally supported (L). Throughout each trial, respiratory gases, heart rate (HR), perceptions of effort and energy expenditure (EE) were measured. Significantly higher EE occurred during P12 (p = 0.01) than during L12 (855.3 ± 104.3; CI = 780.7–930.0 and 801.5 ± 82.2 kcal; CI = 742.7–860.3 kcal, respectively), but not at the other speeds; despite this, perceptions of effort and HR responses were unaffected. This additional EE is likely caused by alterations to posture which increase oxygen demand. The use of such systems is unlikely to affect low-intensity tasks, but researchers should use caution when interpreting data, particularly when exercise duration exceeds 30 min and laboratory-based analysers should be used where possible.

The Effects of Carbohydrate Loading 48 Hours Before a Simulated Squash Match

The aim of this study was to ascertain whether a high carbohydrate diet in the days before movement patterns simulating a squash match would increase carbohydrate oxidation during the match, and alter physical performance. Nine New Zealand level squash players were recruited to complete a simulated squash match on two occasions: 1) following a 48-hr high carbohydrate (11.1g·kg-1); and 2) following a calorie-matched low carbohydrate (2.1 g·kg-1) diet. The interventions were assigned in a randomized, single-blind, cross-over design. The match simulation was designed to mimic a five-game match lasting approximately 1 hr. Performance was measured as time to complete each game. Expired respiratory gases and heart rate were continuously collected throughout the trial using a portable gas analysis system. Capillary blood glucose and lactate samples were obtained during a 90 s rest period between each game. Rating of perceived exertion was also recorded after each set. Respiratory exchange ratio was significantly higher during exercise following the high CHO diet (0.80 vs. 0.76) p < .001) and this was associated with significantly faster time to complete the games (2340 ± 189 s vs. 2416 ± 128 s, p = .036). Blood glucose and lactate concentrations were also significantly higher in the high carbohydrate condition (p = .038 and p = .021 respectively). These results suggest that ingestion of a diet high in carbohydrate (>10 g/kg body weight) preceding simulated competitive squash produces increased rates of carbohydrate oxidation and maintains higher blood glucose concentrations. These metabolic effects were associated with improved physical performance.

Effect of Shoes' Heel Height on the Energy Cost during Jogging

The purpose of this study is to examine the changes of energy cost during a high-heeled continuous jogging. Thirteen healthy female volunteers jointed in this study with heel height of the shoes varied from 1, 4.5 and 7 cm, respectively. Each subjects jogged on the treadmill with K4b2 portable gas analysis system. The results of this study showed that ventilnation, relative oxygen consumption and energy expenditure increased with the increase of heel height and these values shows significantly larger when the heel height reached to 7 cm. Present study suggest that wearing high heel shoes jogging could directly increase energy consumption, causing neuromuscular fatigue.