Mild-to-moderate COVID-19 impact on the cardiorespiratory fitness in young and middle-aged populations

The goal of the present study was to compare pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) performance in COVID-19 survivors with a control group (CG). This was a cross-sectional study. Patients diagnosed with COVID-19, without severe signs and symptoms, were evaluated one month after the infection. Healthy volunteers matched for sex and age constituted the control group. All volunteers underwent the following assessments: i) clinical evaluation, ii) PTF; and iii) CPET on a cycle ergometer. Metabolic variables were measured by the CareFusion Oxycon Mobile device. In addition, heart rate responses, peak systolic and diastolic blood pressure, and perceived exertion were recorded. Twenty-nine patients with COVID-19 and 18 healthy control subjects were evaluated. Surviving patients of COVID-19 had a mean age of 40 years and had higher body mass index and persistent symptoms compared to the CG (P<0.05), but patients with COVID-19 had more comorbidities, number of medications, and greater impairment of lung function (P<0.05). Regarding CPET, patients surviving COVID-19 had reduced peak workload, oxygen uptake (V̇O₂), carbon dioxide output (V̇CO₂), circulatory power (CP), and end-tidal pressure for carbon dioxide (P_ETCO₂) (P<0.05). Additionally, survivors had depressed chronotropic and ventilatory responses, low peak oxygen saturation, and greater muscle fatigue (P<0.05) compared to CG_. Despite not showing signs and symptoms of severe disease during infection, adult survivors had losses of lung function and cardiorespiratory capacity one month after recovery from COVID-19. In addition, cardiovascular, ventilatory, and lower limb fatigue responses were the main exercise limitations.

Reliability and validity of six-minute step test in patients with heart failure

Exercise intolerance is the hallmark consequence of advanced chronic heart failure (HF). The six-minute step test (6MST) has been considered an option for the six-minute walk test because it is safe, inexpensive, and can be applied in small places. However, its reliability and concurrent validity has still not been investigated in participants with HF with reduced ejection fraction (HFrEF). Clinically stable HFrEF participants were included. Reliability and error measurement were calculated by comparing the first with the second 6MST result. Forty-eight hours after participants underwent the 6MST, they were invited to perform a cardiopulmonary exercise test (CPET) on a cycle ergometer. Concurrent validity was assessed by correlation between number of steps and peak oxygen uptake (V̇O₂ peak) at CPET. Twenty-seven participants with HFrEF (60±8 years old and left ventricle ejection fraction of 41±6%) undertook a mean of 94±30 steps in the 6MST. Intra-rater reliability was excellent for 6MST (ICC=0.9), with mean error of 4.85 steps and superior and inferior limits of agreement of 30.6 and -20.9 steps, respectively. In addition, strong correlations between number of steps and CPET workload (r=0.76, P<0.01) and peak V̇O₂ (r=0.71, P<0.01) were observed. From simple linear regression the following predictive equations were obtained with 6MST results: V̇O₂ peak (mL/min) = 350.22 + (7.333 × number of steps), with R²=0.51, and peak workload (W) = 4.044 + (0.772 × number of steps), with R²=0.58. The 6MST was a reliable and valid tool to assess functional capacity in HFrEF participants and may moderately predict peak workload and oxygen uptake of a CPET.

Resistance exercise training improves heart rate variability and muscle performance: a randomized controlled trial in coronary artery disease patients

BACKGROUND

Resistance exercise (RE) is an important part of cardiac rehabilitation. However, it is not known about the low intensity of RE training that could modify the heart rate variability (HRV), muscular strength and endurance in patients with coronary artery disease (CAD).

AIM

To investigate the effects of high repetition/low load resistance training (HR/LL-RT) program on HRV and muscular strength and endurance in CAD patients.

DESIGN

Randomized and controlled trial.

SETTING

Patients seen at the Cardiopulmonary Physical Therapy Laboratory between May 2011 and November 2013.

POPULATION

Twenty male patients with CAD were randomized to a training group (61.3±5.2 years) or control group (61±4.4 years).

METHODS

1 repetition maximum (1-RM) maneuver, discontinuous exercise test on the leg press (DET-L), and resting HRV were performed before and after 8 weeks of HR/LL-RT on a 45° leg press. RMSSD, SD1, mean HR and ApEn indices were calculated. The HR/LL-RT program consisted of a lower limb exercise using a 45° leg press; 3 sets of 20 repetitions, two times a week. The initial load was set at 30% of the 1-RM load and the duration of the HR/LL-RT program was performed for 8 weeks.

RESULTS

After 8 weeks of HR/LL-RT there were significant increases of RMSSD and SD1 indices in the training group only (P<0.05). There was a significant decrease in mean HR after HR/LL-RT in the training group (P<0.05). There was a significantly higher ApEn after in the training group (P<0.05). There were significantly higher values in the training group in contrast to the control group (P<0.05).

CONCLUSION

These results show positive improvements on HRV, as well as muscle strength and endurance in CAD patients.

CLINICAL REHABILITATION IMPACT

Eight weeks of HR/LL-RT is an effective sufficient to beneficially modify important outcomes as HRV, muscle strength and endurance in CAD patients.