Exploratory study on oxygen consumption on-kinetics during treadmill walking in women with systemic lupus erythematosus

Cardiorespiratory Insufficiency and Performance Fatigability in Women with Systemic Lupus Erythematosus

Purpose

Patients with systemic lupus erythematosus (SLE) experience excessive, debilitating fatigue with previously reported evidence of etiologically mediated cardiorespiratory impairments. Performance fatigability provides a precise characterization of fatigue as it can be quantified objectively as a function of time, frequency, and/or duration. Nevertheless, little consideration has been given to understanding performance fatigability and its physiological determinants in those with SLE. The purpose of this study was to characterize performance fatigability in patients with SLE, utilizing measures surrounding the anaerobic threshold, with emphasis on cardiorespiratory impairment as a potential mediating factor.

Methods

This was a case-control study design. 44 physically inactive women, 26 with SLE and 18 controls, completed a treadmill cardiopulmonary exercise test to volitional exhaustion.

Results

There were no significant differences in age (SLE 34.8(9.0) vs Control 36.9(7.3) yrs; p=0.422) between groups. BMI (SLE 27.1(5.4) vs Control 23.8(5.2) kg/m2; p=0.045) was significantly higher in the SLE vs Control group. Resting heart rate (SLE 68(16) vs Control 78(15) bpm; p=0.040) was significantly lower in the SLE compared to the Control group. The VO2 corresponding to the anaerobic threshold (AT-VO2), used to identify the onset of exercise-induced fatigue, was significantly lower in women with SLE than in controls (SLE 12.4(3.1) vs Control 16.4(2.2) ml/kg/min; p<0.001), as was AT-stage (SLE 2.5(0.90) vs Control 3.4(0.78); p=0.002). Additionally, Fatigue Severity Score (FSS) was highly and inversely correlated with AT-VO2 (rho=-0.615; p<0.001) and FSS was highly correlated with Functional Aerobic Impairment Index (FAI; rho=0.663; p<0.001).

Conclusion

This study underscores severe performance fatigability in patients with SLE and its link to cardiorespiratory insufficiency. Physiological presentation of performance fatigability was observed during very low intensities of exercise, emphasizing the negative impact it may have on physical function in this population.

Similar Slow Component of Oxygen Uptake and Ventilatory Efficiency between an Aerobic Dance Session on an Air Dissipation Platform and a Constant-Load Treadmill Test in Healthy Women

There is a lack of evidence about the slow component of oxygen consumption (V.O2sc) and ventilatory efficiency (slope VE·VCO2−1) during an aerobic dance (AD) session on an air dissipation platform (ADP) despite the key role played in endurance exercises. This research was designed to assess V.O2sc, ventilatory efficiency, and blood lactate concentration by comparing two exercise modes: AD session on an ADP versus treadmill test at a constant-load intensity of the first ventilatory threshold (VT1). In the first session, an incremental treadmill test was completed. In sessions 2 and 3, the participants were randomly assigned to the AD session on an ADP or to a treadmill constant-load test at VT1 intensity to determine their cardioventilatory responses. In addition, their blood lactate levels and ratings of perceived exertion (RPE, CR-10) were evaluated. No significant differences were found between the constant-load treadmill test and AD session on an ADP with respect to V.O2sc, VE VCO2−1 slope, and RPE (p > 0.05). Higher blood lactate concentrations were observed in an AD session on an ADP than in a constant-load treadmill test at 10 min (p = 0.003) and 20 min (p < 0.001). The two different exercise modalities showed similar V.O2sc and VE·VCO2−1 slope, even though the blood lactate concentrations were different.

The association of breathing pattern with exercise tolerance and perceived fatigue in women with systemic lupus erythematosus: an exploratory case-control study

The aims of the study were to (1) to characterize the breathing pattern and work of breathing during peak exercise in patients with SLE; (2) to examine the extent to which the breathing pattern and work of breathing impact the exercise capacity and fatigue. Forty-one women participated in the study (SLE: n = 23, median = 35, range = 21-57 years, control: n = 18, median = 38, range = 22-45 years). Each subject performed a treadmill cardiopulmonary exercise test (a modified Bruce treadmill protocol) ending with volitional exhaustion. Breathing mechanic was characterized by measures of expired minute volume (V_E), tidal volume (Vt), respiratory rate (f), work of breathing, and cardiorespiratory fitness was quantified by measures of peak oxygen consumption (VO₂) and time to exhaustion. Data presented as median and interquartile range (IQR). Women with SLE had lower Vt {1221 [488.8] mL/min vs. 1716 [453.1] mL; p = .006}, V_E {58.9 [18.9] L/min vs 70 [28.1] L/min, p = 0.04} and increased breathing frequency {51.5 [10.8] vs 43.6 [37.8] bpm, p = 0.01} compared to the control group. The time to exhaustion and peak VO₂ during the CPET were significantly reduced in those with SLE compared to controls {13.3 [10.2] vs 16.1 [2.2] min; p = 0.004}, {20 [6.1] mL/kg/min vs 26.6 [7] mL/kg/min p < 0.001}, respectively. Differences remained when the analyses were controlled for the observed differences in peak VO₂. When the regression model adjusted for the peak VO₂, it had been shown that Vt, WOB and f were explained variances in the fatigue severity by 64% [p < 0.001]. The decline in V_E and Vt coupled with a decreased peak VO_2, and work of breathing may have contributed to low cardiorespiratory fitness and fatigue in patients with systemic lupus erythematosus.

Measures of excess [Formula: see text]CO2 and recovery [Formula: see text]CO2 as indices of performance fatigability during exercise: a pilot study

BACKGROUND

The severity of performance fatigability and the capacity to recover from activity are profoundly influenced by skeletal muscle energetics, specifically the ability to buffer fatigue-inducing ions produced from anaerobic metabolism. Mechanisms responsible for buffering these ions result in the production of excess carbon dioxide (CO2) that can be measured as expired CO2 ([Formula: see text]CO2) during cardiopulmonary exercise testing (CPET). The primary objective of this study was to assess the feasibility of select assessment procedures for use in planning and carrying out interventional studies, which are larger interventional studies investigating the relationships between CO2 expiration, measured during and after both CPET and submaximal exercise testing, and performance fatigability.

METHODS

Cross-sectional, pilot study design. Seven healthy subjects (30.7±5.1 years; 5 females) completed a peak CPET and constant work-rate test (CWRT) on separate days, each followed by a 10-min recovery then 10-min walk test. Oxygen consumption ([Formula: see text]O2) and [Formula: see text]CO2 on- and off-kinetics (transition constant and oxidative response index), excess-[Formula: see text]CO2, and performance fatigability severity scores (PFSS) were measured. Data were analyzed using regression analyses.

RESULTS

All subjects that met the inclusion/exclusion criteria and consented to participate in the study completed all exercise testing sessions with no adverse events. All testing procedures were carried out successfully and outcome measures were obtained, as intended, without adverse events. Excess-[Formula: see text]CO2 accounted for 61% of the variability in performance fatigability as measured by [Formula: see text]O2 on-kinetic ORI (ml/s) (R2=0.614; y = 8.474x - 4.379, 95% CI [0.748, 16.200]) and 62% of the variability as measured by PFSS (R2=0.619; y =  - 0.096x + 1.267, 95% CI [-0.183, -0.009]). During CPET, [Formula: see text]CO2 -off ORI accounted for 70% (R2=0.695; y = 1.390x - 11.984, 95% CI [0.331, 2.449]) and [Formula: see text]CO2 -off Kt for 73% of the variability in performance fatigability measured by [Formula: see text]O2 on-kinetic ORI (ml/s) (R2=0.730; y = 1.818x - 13.639, 95% CI [0.548, 3.087]).

CONCLUSION

The findings of this study suggest that utilizing [Formula: see text]CO2 measures may be a viable and useful addition or alternative to [Formula: see text]O2 measures, warranting further study. While the current protocol appeared to be satisfactory, for obtaining select cardiopulmonary and performance fatigability measures as intended, modifications to the current protocol to consider in subsequent, larger studies may include use of an alternate mode or measure to enable control of work rate constancy during performance fatigability testing following initial CPET.

Carbon Dioxide Expiration and Performance Fatigability Following Aerobic Exercise Training: A Longitudinal, Observational, Pilot Study

Purpose

This study examined the influence of aerobic exercise training (AET) on components of carbon dioxide expiration (VCO2), cardiorespiratory function, and fatigability.

Methods

Twenty healthy adults completed peak cardiopulmonary exercise (CPX) and submaximal tests before and after a vigorous, 4-week AET regimen. Each test was followed by a 10-min recovery and endurance test at 70% of peak wattage attained during CPX. Fatigability was assessed using testing durations and power output. Respiratory buffering (excess VCO2) and non-buffering (metabolic VCO2) were calculated. Data were analyzed for significance (p<0.05) using regressions and paired t-tests.

Results

Significant improvements in all measures of fatigability were observed after AET. A significant increase in excess VCO2 was observed, though not in metabolic VCO2. Excess VCO2 was strongly predictive of fatigability measures.

Conclusion

Significant decreases in fatigability are often observed in clinical populations such as obstructive or restrictive lung disease or pulmonary hypertension following AET, even when peak cardiorespiratory function does not appear to adapt. Decreases in fatigability appear to predict longevity with no yet identified mechanism. These results suggest that respiratory buffering and metabolic components of VCO2 may adapt independently to AET, introducing foundational plausibility for an influence of respiratory buffering adaptation to AET on fatigability status.

Role of Respiratory Buffering in the Relationship Between Recovery and Performance Fatigability Following Aerobic Exercise Training: A Longitudinal, Observational, Pilot Study

Purpose:

This study characterized the influence of excess expired carbon dioxide (excess V̇co 2) in the relationship between recovery and fatigability.

Methods:

Twenty healthy adults completed peak cardiopulmonary exercise tests (CPXs) and constant work rate tests before and after a vigorous, 4-week aerobic exercise training (AET) regimen. Each test was followed by 10 minutes of recovery and an endurance test at 70% of peak watts attained during CPX. Fatigability was assessed by measures of time to exhaustion and power output. Metabolic and recovery capacity indices were obtained. Data were analyzed using correlations and regressions and compared pre/post AET using paired t tests.

Results:

Significant improvements in recovery and fatigability were observed after AET, along with significant increases in total and excess V̇co 2. Relationships between measures of recovery and fatigability were observed, although strengths of the relationships were diminished after controlling analyses for the effect of excess V̇co 2.

Conclusions:

This study suggests that the ionic buffering capacity may moderate the relationship between recovery and fatigability. These results could have implications regarding AET-induced buffering dynamics, and its role in fatigue resistance when performing activities above moderate intensities. This may be of particular importance in patients with cardiopulmonary complications, unable to improve peak aerobic capacity.

Supervised walking improves cardiorespiratory fitness, exercise tolerance, and fatigue in women with primary Sjögren's syndrome: a randomized-controlled trial

OBJECTIVE

The aim of this study was to evaluate the safety and effectiveness of a supervised walking program in women with primary Sjögren's syndrome (pSS).

METHODS

Forty-five sedentary women fulfilling the American European Consensus Criteria for pSS were randomized to a training group (TG, n = 23) or control group (CG, n = 22). Patients in the TG were submitted to supervise walking three times a week for 16 weeks. The patients of the CG were instructed to not perform any kind of regular physical exercise. Physical fitness [maximum oxygen uptake (VO2max) and distance], EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI), hematological tests, and Medical Outcomes Study 36 (SF-36) were assessed at baseline and week 16. In addition, EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI), Functional Assessment of Chronic Illness Therapy Fatigue Subscale (FACIT-fatigue), and Beck Depression Inventory (BDI) were measured prior to intervention, after 8 and 16 weeks. Patient global assessment of response to therapy was completed at the final assessment. An intent-to-treat analysis was performed.

RESULTS

After 16 weeks, the mean change of VO2max (ml/kg/min), distance, and FACIT-fatigue were higher in the TG than in the CG (p = 0.016, p = 0.043 and p = 0.030, respectively). Improved cardiorespiratory fitness was associated with improvements in fatigue scores and physical components of quality of life (SF-36). Furthermore, improved fatigue scores were associated with reduced depression and improvements in the physical and mental components of SF-36. Overall, 95.4% of patients in the TG rated themselves as clinically improved versus 62% of the patients in the CG (p = 0.049). There was no flare in disease activity and no serious adverse events with exercise.

CONCLUSIONS

This supervised walking program was demonstrated to be feasible and safe with improvements in cardiorespiratory fitness, exercise tolerance, fatigue, and patient perception of improvement in pSS patients.

TRIAL REGISTRATION

Clinical Trials.gov ID, number NCT02370225.

Fatigability, oxygen uptake kinetics and muscle deoxygenation in incomplete spinal cord injury during treadmill walking

PURPOSE

The purpose of the present study was to characterize hypothesized relationships among fatigability and cardiorespiratory fitness in individuals with chronic motor-incomplete SCI (iSCI) during treadmill walking. The theoretical framework was that exacerbated fatigability would occur concomitantly with diminished cardiorespiratory fitness in people with iSCI.

METHODS

Subjects with iSCI (n = 8) and an able-bodied reference group (REF) (n = 8) completed a 6-min walking bout followed by a walking bout of 30-min or until volitional exhaustion, both at a self-selected walking speed. Fatigability was assessed using both perceived fatigability and performance fatigability measures. Pulmonary oxygen uptake kinetics (VO₂ on-kinetics) was measured breath-by-breath and changes in deoxygenated hemoglobin/myoglobin concentration (∆[HHb]) of the lateral gastrocnemius was measured by near-infrared spectroscopy. Adjustment of VO₂ and ∆[HHb] on-kinetics were modeled using a mono-exponential equation.

RESULTS

Perceived fatigability and performance fatigability were 52% and 44% greater in the iSCI group compared to the REF group (p = 0.003 and p = 0.004). Phase II time constant (τp) of VO₂ on-kinetics and ∆[HHb] ½ time during resting arterial occlusion were 55.4% and 16.3% slower in iSCI vs REF (p < 0.01 and p = 0.047, respectively).

CONCLUSIONS

The results of the present study may suggest that compromised O₂ delivery and/or utilization may have contributed to the severity of fatigability in these individuals with iSCI. The understanding of the extent to which fatigability and VO₂ and Δ[HHb] on-kinetics impacts locomotion after iSCI will assist in the future development of targeted interventions to enhance function.

Effects of a one-year physical activity programme for women with systemic lupus erythematosus - a randomized controlled study

OBJECTIVES

To study the effects of a one-year physical activity programme on aerobic capacity, physical activity and health-related quality of life (HRQL) in patients with systemic lupus erythematosus (SLE) by a randomized control design.

METHODS

Thirty-five women with low or moderate disease activity and organ damage were randomized to intervention (I) or control (C) group. The intervention during months 0-3 consisted of education, supervised aerobic exercise at high intensity and individual coaching, as well as self-managed physical activity at low-to-moderate intensity. During months 4-12, the physical activity was self-managed and the coaching was successively reduced over time. Outcome measures included: maximal oxygen uptake (VO2 max) from a bicycle ergometer test, self-reported physical activity and HRQL (SF-36).

RESULTS

VO2 at sub-max. and max. increased, independent of group, during the one-year study period (main effect of time p < 0.0001). VO2 max. increased between baseline and month 3 (p < 0.0001), between months 3 and 6 (p = 0.01) and the increase was sustained at month 12 (ns). Frequency of physical activity at high intensity also increased, independent of group, during the study period. It was increased at months 3, 6 and 12 compared to baseline (p = 0.02, p < 0.001, p = 0.03). Improvement in mental health between baseline and month 6 (p = 0.002) was seen for the I-group, not the C-group (p = 0.03). Disease activity and organ damage did not change.

CONCLUSIONS

Physical activity and aerobic capacity increased after supervised exercise and coaching, and the improvement was sustained during the one-year programme. However, no interactions between the group differences were seen, which suggests that repeated measurements could motivate to increased physical activity and thereby to increased aerobic capacity. As sub-max. VO2 increased over time, training-induced changes in VO2 on-kinetics could be another explanation. Little influence on HRQL was seen after the programme. The study indicates that physical activity at high intensity over one year is tolerated by patients with mild to moderate SLE.