Description of physical activity in children with juvenile idiopathic arthritis using accelerometry.

OBJECTIVES: Juvenile idiopathic arthritis (JIA) can lead to functional impotence and reduced physical activity (PA) in patients. The objective of this study was to monitor the daily PA of children aged 6-18 years with JIA using accelerometry based on disease activity and individual abilities, and to compare this with age recommendations. METHODS: Patients volunteering for the study wore an accelerometer for 7 consecutive days; data were evaluated using a wGT3X ActiGraph™. The 2010 World Health Organization (WHO) recommendations were used for comparison. RESULTS: We collected accelerometry data for 24 patients of the University Hospital Center (UHC) of Besançon. Only two patients did not reach the recommendations of moderate-to-vigorous PA (MVPA). Time spent in MVPA was negatively correlated with age, BMI, number of joints with active arthritis, JADAS score, and visual analogue pain assessment (VAPA). Patients with active disease, those with upper extremity pain, and female patients had significantly lower PA scores. CONCLUSIONS: Almost all of the patients of the UHC of Besançon who accepted the study reached the WHO recommendations. Having an active disease, having painful upper limbs, or being a girl is associated with decreased PA.

Local ice cryotherapy decreases synovial interleukin 6, interleukin 1ß, vascular endothelial growth factor, prostaglandin-E2, and nuclear factor kappa B p65 in human knee arthritis: a controlled study.

BACKGROUND: The aim of this study was to assess the anti-inflammatory effects of local cryotherapy in human non-septic knee arthritis. METHODS: In the phase I of the study, patients were randomized to receive either ice (30 min; N = 16) or cold CO2 (2 min; N = 16) applied twice during 1 day at an 8-h interval on the arthritic knee. In phase II, 16 other ice-treated arthritic knees according to the same protocol were compared to the contralateral non-treated arthritic knees (N = 16). The synovial fluid was analyzed just before the first cold application, then 24 h later. IL-6, IL-1ß, TNF-α, IL-17A, VEGF, NF-kB-p65 protein, and PG-E2 levels were measured in the synovial fluid and compared before/after the two cold applications. RESULTS: Forty-seven patients were included (17 gouts, 11 calcium pyrophosphate deposition diseases, 13 rheumatoid arthritides, 6 spondyloarthritides). Local ice cryotherapy significantly reduced the IL-6, IL-1ß, VEGF, NF-kB-p65, and PG-E2 synovial levels, especially in the microcrystal-induced arthritis subgroup, while only phosphorylated NF-kB-p65 significantly decreased in rheumatoid arthritis and spondyloarthritis patients. Cold CO2 only reduced the synovial VEGF levels. In the phase II of the study, the synovial PG-E2 was significantly reduced in ice-treated knees, while it significantly increased in the corresponding contralateral non-treated arthritic knees, with a significant inter-class effect size (mean difference - 1329 [- 2232; - 426] pg/mL; N = 12). CONCLUSIONS: These results suggest that local ice cryotherapy reduces IL-6, IL-1ß, and VEGF synovial protein levels, mainly in microcrystal-induced arthritis, and potentially through NF-kB and PG-E2-dependent mechanisms. TRIAL REGISTRATION: Clinicaltrials.gov, NCT03850392-registered February 20, 2019-retrospectively registered.

The effects of a calf pump device on second half performance of a simulated soccer match in competitive youth players.

During soccer matches, performance decrements have been reported that relate to both physical abilities and technical skills. To investigate the effects of low-frequency electrical stimulation LFES (VeinoplusSport®, Ad Rem Technology, France) administered during half-time recovery on performance alterations during the second half. Twenty-two highly trained young players undertook a soccer-match simulation (SAFT90). During half-time, they were randomly assigned to LFES group or Placebo group. Each half was split into 3 bouts of 12 minutes. Following each bout, maximal strike speed (MSS), sprint test (ST), maximal sprint accelerations (MA) and metabolic power (MP) were determined in both groups. Arterial (AF) and venous flows (VF) were measured at rest and at the end of half-time. LEFS group exhibited beneficial effects on performance compared to the Placebo group with a likely effect for MSS, ST, MA, and a possible effect for MP. AF and VF increased statistically more in LEFS group compared to Placebo group. The use of specific calf-pump LFES during half-time of a youth simulated soccer match attenuated the decrease in performance during the second half compared to Placebo group. This effect is most marked at the beginning of the second half with regards to explosive parameters.

Intermittent versus constant aerobic exercise in middle-aged males: acute effects on arterial stiffness and factors influencing the changes.

PURPOSE: Both constant and intermittent acute aerobic exercises have been found to decrease arterial stiffness. However, direct comparisons of these two types of exercise are sparse. It is not known which type of exercise has the greatest effect. METHODS: We evaluated the haemodynamic responses in 15 males (age 48.5 ± 1.3 years; BMI 27.5 ± 0.8 kg m-2) following acute constant (CE) and intermittent cycling exercise (IE). Duration and heart rate were matched during both exercises (131.8 ± 3.2 bpm for CE and 132.0 ± 3.1 bpm for IE). Central and peripheral arterial stiffness was assessed through pulse wave velocity (PWV). Plasma concentrations of nitric oxide (NO), atrial natriuretic peptide (ANP), blood lactate, noradrenaline, and adrenaline were measured before and after each exercise. RESULTS: Central (+ 1.8 ± 7.4 and - 6.5 ± 6.8% for CE and IE) and upper limb PWV (+ 2.7 ± 6.2 and - 8 ± 4.6% for CE and IE) were not significantly altered although a small decrease (small effect size) was observed after IE. However, lower limb PWV significantly decreased after exercises (- 7.3 ± 5.7 and - 15.9 ± 4% after CE and IE), with a larger effect after IE. CONCLUSIONS: Greater decrease in lower limb PWV occurred after IE despite greater heart rate. This may be due to the higher blood levels of lactate during IE, while NO, ANP, noradrenaline, and adrenaline levels remained not statistically different from CE. These results underlined the importance of lactate in triggering the post-exercise vascular response to exercise, as well as its regional characteristic.

Changes in tissue oxygen saturation with calf compression sleeve: before, during and after a cycling exercise.

AIM: The purpose of this study was to examine the changes in tissue oxygen saturation (StO2) with calf compression sleeves, before, during and after a cycling exercise. METHODS: Eleven athletes came to the laboratory two times, to complete the same session with or without calf compression sleeves, in a randomized order. The session included a 15-min incremental cycling exercise: 3 min at each intensity - 40, 80, 120, 160 and 200 W, preceded (baseline) and followed (recovery) by a 10-min period at rest in seated position. Calf StO2 was recorded using near infrared spectroscopy during the three last min of the baseline period, during the cycling exercise and during the recovery period. RESULTS: Baseline StO2 was significantly increased with the compression sleeves (P<0.001; +24.8±3.5%). During the cycling exercise, StO2 was significantly increased with the compression sleeves only at 40 W (P<0.05; +8.2±3.7%) and 80 W (P<0.05; +7.9±3.7%). At 120 W (P=0.23; +5.0±4.0%), 160 W (P=0.38; +3.9±4.1%) and 200 W (P=0.81; -0.1±4.9%), no significant difference was found with compression sleeves. During the recovery period, StO2 was significantly increased with the compression sleeves (1 to 10 min: P<0.001; +10.5±1.3%). CONCLUSION: This study shows that wearing calf compression sleeves increases StO2 at rest (before and after an exercise) and at low intensities in cycling (40 W and 80 W). At high intensities (120 W and more), compression sleeves is not useful to increase StO2.

Effects of three postexercice recovery treatments on femoral artery blood flow kinetics.

AIM: This study aimed to compare the kinetics of muscle leg blood flow during three recovery treatments following a prolonged exercise: contrast water therapy (CWT), compression stockings (CS) or passive recovery (PR). METHODS: Fifteen men came to the laboratory three times to perform a 45-min exercise followed 5 min after by a standardized 12-min recovery treatment in upright position, alternating between two vats every 2 min: CWT (cold: ~12 °C to warm: 36 °C), CS (~20 mmHg) or PR. The order of treatments was randomized. Blood flow was measured using Doppler ultrasound during the recovery treatments (i.e., min 3, 5, 7 and 9) in the superficial femoral artery distally to the common bifurcation (~3 cm) (above the water and stocking). RESULTS: Blood flow was significantly higher during CWT (P<0.01; +22.91%) and CS (P<0.05; +15.26%) than during PR. Although no statistical difference between CWT and CS was observed, effect sizes were larger during CWT (large) than during CS (moderate). No changes in blood flow occurred in the femoral artery between hot and cold transitions of CWT. CONCLUSION: During immediate recovery of a high intensity exercise, CWT and CS trigger higher femoral artery blood flow than PR. Moreover, effect sizes were greater during CWT than during CS.

Changes in femoral artery blood flow during thermoneutral, cold, and contrast-water therapy.

AIM: The purpose of this study was to examine the changes in femoral artery blood flow during cold water immersion (CWI), contrast water therapy (CWT) and thermoneutral water immersion (TWI). METHODS: Ten athletes came to the laboratory three times, to complete a 20-min procedure in upright position: 4 min in air (baseline), then 16-min full leg TWI (~35 °C), CWI (~12 °C) or CWT (2:2 ~12 °C to ~35 °C) min ratio, in a random order. Blood flow was measured every 2 min: baseline (i.e. min 3 and 1) and throughout water immersion (i.e. min 1, 3, 5, 7, 9, 11, 13 and 15), using Doppler ultrasound in the superficial femoral artery, distal to the common bifurcation (~3 cm), above the water and stocking. RESULTS: Compared with baseline, blood flow was significantly higher throughout TWI (min 1 to 15: P<0.001; +74.6%), significantly lower during CWI (from min 7 to 15: P<0.05; -16.2%) and did not change during CWT (min 1 to 15). No changes in blood flow occurred between the hot and cold transitions of CWT. CONCLUSION: This study shows that external hydrostatic pressure (TWI ~35 °C) significantly increases femoral artery blood flow. We also show that associating hydrostatic pressure with cooling (CWI ~12 °C) decreases femoral artery blood flow after a sufficient duration, whereas associating hydrostatic pressure with alternating brief exposures to contrasted temperatures does not change femoral artery blood flow under resting conditions.

Accuracy of the Minicardio system for heart rate variability analysis compared to ECG.

AIM: The purpose of this investigation was twofold: firstly, to assess the accuracy of heart rate (HR) measurements from Minicardio compared to a standard electrocardiogram (ECG) and secondly, to compare the heart rate variability analysis carried out for each set of data. METHODS: Fifteen young participants volunteered for this study and were instrumented for the simultaneous recording of HR via ECG and Minicardio. HR was recorded continuously during 10 minutes of supine rest and 2 consecutive exercise bouts (target HR at 130 bpm and 150 bpm). R-R intervals were determined in order to compare the number and type of artifacts in each data set. The device were then compared by determining the type and number of artifacts, correlations between HRV analysis parameters and Bland-Altman limits of agreement. RESULTS: No artifact was produced from ECG. With Minicardio, no artifact was produced during supine rest, during exercise there were 2 type 1 (long R-R interval) and 7 type 2 artifacts (short R-R interval). For time domain analysis, Pearson coefficients were 1 for SDNN and mean R-R interval and 0.99 for RMSSD and pNN50. For frequency domain analysis, Pearson coefficients were 0.99 for high frequency and low frequency power, and 0.99 for Poincaré plots SD1 and SD2. Limits of agreement from Bland-Altman analysis showed an excellent agreement between all devices CONCLUSION: The similarity between ECG and Minicardio encourages us to use Minicardio as a portable HR recorder for subjects at rest and during moderate cycling exercise.

Autonomic recovery following sprint interval exercise.

The autonomic nervous activity was assessed following supramaximal exercise through heart rate (HR) and blood pressure (BP) variability (HRV and BPV) and baroreflex sensitivity (BRS). The beat-to-beat HR and BP were recorded during the supine and standing states before (PRE) and at 60 (R60) and 120 min (R120) following single (one Wingate, 1W) and multiple sprint intervals (four Wingates interspersed with 4 min of light cycling, 4W). The supine low frequency (LF) component was increased (P<0.001) and the high frequency (HF) was reduced (P<0.01) at R60 (LF, 178.1 ± 11.0; HF, 74.8 ± 10.5) compared with PRE (LF, 140.2 ± 7.4; HF, 110.4 ± 7.2) after both exercises. Supine systolic BPV LF:HF was higher at R60 (4.6 ± 1.4) compared with PRE (6.8 ± 2.4) only after 4W (P=0.035). Supine BRS was lower (P<0.001) at R60 (6.8 ± 1.1) than at PRE (15.3 ± 1.8) and R120 (11.3 ± 1.3). BRS at R120 remained lower after 4W (P=0.02). Standing BRS was less (P<0.001) at R60 (2.3 ± 0.5) than at PRE (5.6 ± 0.8) or R120 (3.7 ± 0.6) and returned to PRE values only after 1W. We concluded that (a) autonomic balance is shifted to a greater sympathetic and less parasympathetic activation following both types of exercise, (b) it takes longer than 1 h to recover following supramaximal exercise and (c) the recovery is longer after 4W than 1W.

Heart rate variability to assess ventilatory thresholds: reliable in cardiac disease?

BACKGROUND: The first (VT1) and second (VT2) ventilatory thresholds are landmarks to tailor exercise rehabilitation in coronary artery disease (CAD) or chronic heart failure (CHF). Methods allowing VT1 and VT2 determination based on heart rate variability (HRV) have been proposed but not yet evaluated in these patients. DESIGN: To determine the heart rate (HR) associated with VT1 and VT2 by three methods of HRV analyses. METHODS: Fourteen CHF and 24 CAD patients performed an exercise test on a cycle ergometer (10 -W every minute until exhaustion). VT1 and VT2 were determined with the 'respiratory equivalent' method. HR at VT1 was determined with the standard deviation (SD) of R⊟R intervals (VT(SD)) and of the instantaneous beat-to-beat variability of the Poincaré plot method (VT(Poincaré)). HR at VT1 and VT2 was determined through a time-varying HRV analysis method (VT(TV1) and VT(TV2), respectively). RESULTS: HR at VT(SD) was significantly higher than HR at VT1. No significant differences were observed between HR at VT(Poincaré), VT(TV1), and at VT1, nor between HR at VT(TV2) and VT2. HR at VT(SD), VT(Poincaré), and VT1 were significantly correlated, but with a low r (2) value and a large mean HR difference. With the time-varying method, the mean HR difference was lower than 5% and the correlation coefficients were higher (especially for VT(TV2)). CONCLUSIONS: SD and Poincaré plot methods lead to substantial inaccuracy in HR estimates. The time-varying HRV analysis led to strong correlation coefficients and low limits of agreement. Therefore, this method may be a promising, low-cost tool for non-invasive assessment of the ventilatory thresholds in cardiac disease.

Compression sleeves increase tissue oxygen saturation but not running performance.

The purpose of this study was to determine the effects of calf compression sleeves on running performance and on calf tissue oxygen saturation (StO2) at rest before exercise and during recovery period. 14 moderately trained athletes completed 2 identical sessions of treadmill running with and without calf compression sleeves in randomized order. Each session comprised: 15 min at rest, 30 min at 60% maximal aerobic velocity determined beforehand, 15 min of passive recovery, a running time to exhaustion at 100% maximal aerobic velocity, and 30 min of passive recovery. Calf StO2 was determined by near infra-red spectroscopy and running performance by the time to exhaustion. Compression sleeves increased significantly StO2 at rest before exercise (+ 6.4±1.9%) and during recovery from exercise (+ 7.4±1.7% and + 10.7±1.8% at 20th and 30th min of the last recovery period, respectively). No difference was observed between the times to exhaustion performed with and without compression sleeves (269.4±18.4 s and 263.3±19.8 s, respectively). Within the framework of this study, the compression sleeves do not improve running performance in tlim. However the StO2 results argue for further interest of this garment during effort recovery.

Evaluation of cardiorespiratory functional reserve from arm exercise in the elderly.

BACKGROUND: When the subject is not able to satisfy traditional testing procedures, alternative exercises or indices such as arm cranking or the oxygen uptake efficiency slope (OUES) have been proposed. However, the OUES has not yet been used on elderly subjects from an exercise performed with the arms. OBJECTIVE: The aim of our study was to evaluate the possibility of using the OUES as an index of the cardiorespiratory functional reserve in the elderly when the exercise evaluation test is performed with the arms and when this parameter is estimated from submaximal responses. METHODS: Seventeen adults (62-82 years) undergoing total joint arthroplasty of the hip took part in this study. Maximal incremental exercise tests were performed on an arm crank ergometer 1 month before (T1) and 2 months after (T2) surgery. Gas exchanges were measured continuously to determine oxygen consumption at peak exercise (V˙O2 peak) and were used to calculate the OUES. The correlation coefficient was calculated between V˙O2 peak and OUES, and their relative changes between T1 and T2. RESULTS: V˙O2 peak was not significantly different between T1 and T2: 10.3 ± 0.7 and 9.8 ± 0.5 mL/min per kilogramme respectively. The OUES estimated from submaximal responses did not show a significant difference between T1 and T2. Significant correlations were observed between individual V˙O2 peak and OUES, as well as at T1 and T2. CONCLUSION: The use of arm cranking exercises and the calculation of the OUES from the submaximal respiratory response can be used for the objective quantification of cardiorespiratory functional reserve in the elderly.

Effects of a primary rehabilitation programme on arterial vascular adaptations in an individual with paraplegia.

OBJECTIVE: Evaluation of the effects of 6 weeks of wheelchair endurance training on arterial stiffness in an individual with paraplegia. METHODS: A 22-year-old male patient with complete (ASIA A) paraplegia (T11) was tested before and after training (30 minutes three times per week). Physical performance and cardiorespiratory response were evaluated during a maximal progressive test. Heart rate (HR), blood pressure, stroke volume and arterial carotid-wrist and carotid-ankle pulse wave velocity (PWV) were measured at rest. RESULTS: Maximal responses registered (maximal tolerated power, VO2 peak) during the exercise test were increased after training. At rest, HR as PWV decreased, whereas cardiac output and blood pressure remained constant. CONCLUSION: Continuous exposure of the subject to a repeated high intensity exercise bout for 6 weeks elevated fitness level. Such a regular practice might also constitute a major way to trigger vascular remodelling beyond to the trained body part.

Changes in oxygen uptake, shoulder muscles activity, and propulsion cycle timing during strenuous wheelchair exercise.

STUDY DESIGN: Cross-over study. OBJECTIVE: To determine the effect of strenuous wheelchair exercise on oxygen uptake (VO2 ), muscle activity and propulsion cycle timing (including the push time and recovery time during one full arm cycle). SETTING: Laboratory of Sport Sciences at the University of France-Comte in France. METHODS: Two exercise bouts of 6-min duration were performed at a constant workload: (1) non-fatigable exercise (moderate workload) and (2) fatigable exercise (heavy workload). Measurement of VO2, surface electromyographic activity (EMG) from shoulder muscles, and temporal parameters of wheelchair ergometer propulsion were collected from eight able-bodied men (26+/-4 years). RESULTS: A progressive increase in VO2 associated with EMG alterations (P<0.05), and a decrease of the cycle and recovery time (P<0.05) during the heavy exercise. Whereas the push time remained constant, an increased muscle activation time (P<0.05) was found during heavy exercise. CONCLUSION: Observations during wheelchair ergometry indicate the development of fatigue and inefficient muscle coordination, which may contribute to deleterious stress distributions at the shoulder joint, increasing susceptibility to injury.

Late effects of cycle competition on arterial stiffness. A preliminary study.

AIM: The purpose of this study was to examine the effects of a cycle competition on the large arteries stiffness, 24-hours after the end of the effort. METHODS: Two males elite cyclists were studied before and after performing a stage-race. Their heart rate (HR) was measured continuously during the two competition days. The impact of the competition on their vascular system was determined using the measure of pulse wave velocity (PWV), an index of regional arterial stiffness. HR and blood pressure were also measured before and 24-hours postexercise. RESULTS: During the race, mean cyclists HR were relatively similar. Changes in PWV and HR were found after competition: these measures increased for the offensive subject and decreased for the other. CONCLUSIONS: Despite their involvement in the same cycling competition, we suggest that the long-term effects induced by effort on arterial stiffness were inverted according to the subject's comportment during the race. This study should be completed by others measures in order to precise our results and to precise the possible link between arteries stiffness and the recovery kinetic process, both depending on the cardiovascular autonomic nervous system control.

Degree of coordination between breathing and rhythmic arm movements during hand rim wheelchair propulsion.

This study aimed (i) to quantify the spontaneous coordination between breathing and hand rim wheelchair propulsion, (ii) to manipulate arm movement frequency and assess its effects on spontaneous coordination, and (iii) to investigate the hypothesis that entrainment of breathing improves economy of locomotion and leads to a lower rate of perceived exertion (RPE) compared with spontaneous breathing. Nine male, able-bodied participants completed four bouts of 6 min submaximal steady state exercise at 60 % of maximal propulsion velocity on a wheelchair ergometer, with spontaneous breathing and arm frequencies (Fspont), with 20 % higher and lower arm frequencies (F +20 and F -20, respectively) compared to Fspont accompanied with spontaneous breathing frequency, and by synchronising expiration phase with pushing time and inspiration phase with upper limb recovery time (C). Oxygen uptake and propulsion frequency were continuously recorded. The degree of coordination was expressed as a percentage of inspiration starting in the same phase of the wheelchair propulsion cycle (i.e. pushing and recovery times). No difference in degree of coordination was observed between Fspont, F -20 and F +20 conditions (49.2 +/- 12.1 %, 49.1 +/- 29.0 % and 48.2 +/- 29.4 %, respectively). Oxygen uptake increased significantly during C condition while RPE was significantly lower for C and F -20 (p < 0.05) compared to F +20 conditions. Contrary to what we expected, entrainment of breathing using a monofrequency ratio (C) induced a higher energy cost probably due to the mechanical properties of the wheelchair propulsion activity itself. In conclusion, this study showed that the same locomotor-respiratory coupling occurred during hand rim wheelchair propulsion regardless of the arm movement frequency, and that entrainment of breathing did not improve economy of locomotion.

Evaluation of fitness level by the oxygen uptake efficiency slope after a short-term intermittent endurance training.

Several indicators are used as indices of cardiorespiratory reserve. Among them, oxygen uptake (VO(2)) at peak and ventilatory threshold (VAT) levels are the most common used. In the present study, endurance training was used to evaluate and compare the usefulness of a new index, the Oxygen Uptake Efficiency Slope (OUES) as an alternative to the previous ones. Fifteen physical education student women participated in the study (8 as a trained group [T: age (mean +/- SD) 21.9 +/- 3.3 y, height 165.1 +/- 5.5 cm, weight 60.4 +/- 3.3 kg] and 7 as a control group [C: age 21.7 +/- 1.9 y, height 165.4 +/- 7.2 cm, weight 59.6 +/- 8.6 kg]). Before and after 6 weeks of the Square-Wave Endurance Exercise Test (SWEET) training program or daily activities, they performed an incremental test (30 W/3 min) on a cycle ergometer to determined VO(2), power output and parameters associated with breathing efficiency (the respiratory equivalents, and the ventilatory dead space to tidal volume ratio [Vd/Vt]) at peak- and VAT-levels. The slope of the relationship between ventilation and carbon dioxide production was also calculated. OUES, derived from the logarithmic relationship between VO(2) and minute ventilation (V(E)), was determined at 75 % (OUES75), 90 % (OUES90) and 100 % (OUES100) of exercise duration. After endurance training in T, VO(2) and power output were significantly improved at peak- and VAT-levels while all breathing efficiency indices remained unchanged. No changes were observed in C after 6 weeks. Despite significant correlation between OUES values and VO(2) at peak- and VAT-levels, OUES75, OUES90 and OUES100 did not significantly change after endurance training. While VO(2) and power output at peak- and VAT-levels increased in all T, training-induced changes in OUES appeared more variable. We concluded that OUES was not sufficiently sensitive to highlight improvement of cardiorespiratory reserve after endurance training whereas VO(2) at peak and VAT levels did.

Measurements of cardiac output during constant exercises: comparison of two non-invasive techniques.

We compared cardiac output (CO) determined simultaneously by electrical impedance cardiography method (CO (ICG)) and by the CO (2) rebreathing technique (CO (2REB)) during three different steady-state exercises (target heart rate of 120, 140, and 160 min (-1)) in 8 healthy fit young men. The mean difference correlation coefficient obtained between the values of CO (ICG) and CO (2REB) was 0.85 and the mean difference (CO (ICG)-CO (2REB)) was 0.06 l/min (0.12 %). At 120 min (-1), CO (ICG) was lower than CO (2REB) but the tendency was reversed at 140 and 160 min (-1) where CO (ICG) was higher than CO (2REB). This evolution may be explained by the difficulty of using CO (2) rebreathing technique at the highest steady-state exercises and by the progressive acidemia due to exercise. The present results suggest that electrical impedance cardiography method provides acceptable evaluation of CO and may favourably replace the CO (2) rebreathing technique during mild (or moderate) to high steady-state exercises.

Surface electromyography of nine shoulder muscles in two iron cross conditions in gymnastics.

AIM: The rules of gymnastics impose an element of static strength such as an iron cross (IC) on the rings. For IC training, coaches use a custom made device -- the herdos -- to simulate the conditions of competition. The purpose was to compare muscle activity and coordination during IC performed both on the rings and using herdos. Secondly, we tried to determine whether herdos usage induced functional adaptations of the shoulder muscles. METHODS: Six male gymnasts performed 10 IC in each condition. Surface electromyogram of muscles pectoralis major, latissimus dorsi, teres major, infraspinatus, rhomboideus, trapezius, serratus anterior, biceps brachii, and triceps brachii in the right shoulder were analysed using root-mean-square (RMS), and muscle part's in each condition. Muscle part represents the contribution of each of the 9 shoulder muscles studied in each condition. Total muscle activity (SUM) was also used to compare the 2 conditions. RESULTS: Except for the muscle teres major, the RMS decreases (p<0.05) when using the herdos. The SUM also decreases (p<0.05) when using this device. The muscle parts indicate that the contribution of the muscle latissimus dorsi decreases (p<0.05) when using the herdos. These results suggest that the herdos modified shoulder coordination. But their usage does not seem to induce any functional adaptations of these muscles. CONCLUSIONS: The herdos do not seem to provide a valid method to reproduce the same shoulder coordination as on the rings. Therefore IC training with this special device could be called in question.

Effects of a wheelchair ergometer training programme on spinal cord-injured persons.

STUDY DESIGN: Before and after investigation of the effects of a wheelchair ergometer Training programme. OBJECTIVE: To investigate the effects of an original interval-training programme on work capacity and cardiorespiratory variables with spinal cord-injured persons (SCIP's) on a wheelchair-specific ergometer. SETTING: BESANCON, FRANCE. METHODS: Seven SCIP's (male) performed 45 min of wheelchair ergometry three times per week, for 6 weeks. Training effects on maximal dynamic performance and endurance capacity were studied by comparison of performance and cardiorespiratory responses observed during both a maximal progressive test (10 W/2 min) and the same training session performed before and after training. RESULTS: Training induced significant improvements in maximal tolerated power (+19.6%), in peak oxygen consumption (VO2,+16%), and in oxygen pulse (O2p,+18.7%). At ventilatory threshold, significant improvements were also observed in power output (+63%), VO2VT(+ 34.1), ventilation VEVT(+ 37.1%), and V2pVT(+ 19.9% ). Heart rate and ventilation were significantly lower (-11 and -14.6%, respectively) after training at the same work rate, while VO2 was unchanged. Between the first and the last training session, the total physical work was improved by 24.7%, whereas heart rate was unchanged. CONCLUSION: An interval-training programme individualised to each paraplegic subject using a wheelchair ergometer can significantly improve the fitness level and endurance capacity.