Philip Maffetone , Paul B. Laursen

Front.Physiol. 02 April 2020         https://doi.org/10.3389/fphys.2020.00296

The earliest humans relied on large quantities of metabolic energy from the oxidation of fatty acids to develop larger brains and bodies, prevent and reduce disease risk, extend longevity, in addition to other benefits. This was enabled through the consumption of a high fat and low-carbohydrate diet (LCD). Increased fat oxidation also supported daily bouts of prolonged, low-intensity, aerobic-based physical activity. Over the past 40-plus years, a clinical program has been developed to help people manage their lifestyles to promote increased fat oxidation as a means to improve various aspects of health and fitness that include reducing excess body fat, preventing disease, and optimizing human performance. This program is referred to as maximum aerobic function, and includes the practical application of a personalized exercise heart rate (HR) formula of low-to-moderate intensity associated with maximal fat oxidation (MFO), and without the need for laboratory evaluations. The relationship between exercise training at this HR and associated laboratory measures of MFO, health outcomes and athletic performance must be verified scientifically.

Dawkins C; Hollingsworth AC; Milburn S; Cheesman M; Walker P; Mofidi R;

The Journal of cardiovascular surgery [J Cardiovasc Surg (Torino)] 2020 Apr 01. Date of Electronic Publication: 2020 Apr 01.

Background: Vascular Services Quality Improvement Program (VSQIP) was introduced to reduce mortality from elective repair of AAA in the United Kingdom. This study examines the differences in perioperative mortality and postoperative survival between men and women following elective repair of AAAs in the 10 years after implementation of the (VSQIP).
Methods: Consecutive patients who underwent elective repair of AAA between 1stJanuary 2008 and 31st March 2018 were included. All patients were assessed using the nationally agreed VSQIP pathway which involved cardiopulmonary exercise testing as well as contrast enhanced CT scan of aorta and multidisciplinary assessment to plan each treatment. CT scans were examined to assess the morphology of AAA. Patients were stratified by age, gender, AAA morphology and preoperative anaerobic threshold. Postoperative survival was assessed using Kaplan-Meier analysis. Cox regression analysis was used to determine predictors of postoperative mortality.
Results: A total of 702 patients underwent elective repair of AAA of whom 632 were men and 70 were women. The mean age of study cohort was 73.5 years (std. dev: 7.3) and mean AAA diameter was 62 mm (std. dev.: 9.9). Two hundred and forty four patients underwent open repair, 402 underwent standard infra renal Endovascular Aneurysm Repair (EVAR) and 56 underwent complex EVAR with perioperative and 30 day mortality of 1.13%. No significant difference was observed in perioperative/30 day mortality between men and women (χ2=0.06, P=0.81). Anaerobic threshold< 8 (HR: 95%CI: 0.68 (0.51-0.92)), complex aneurysm morphology (HR: 95%CI: 1.7 (1.39-2.19)) risk category (HR: 95%CI: 1.89 (1.48-2.42)) and patients age (HR: 95%CI: 1.41 (1.13-1.89)) were independent risk factor for mortality following repair of AAA, whilst female gender [(HR: 95%CI: 0.89 (0.54-1.48)] and AAA size [(HR: 95%CI: 1.01 (0.84-1.22)] were not. There was no difference in post- operative survival between men and women who underwent elective repair of AAA (Log rank: 1.82 P=0.61).
Conclusions: Following the implementation of VSQIP female gender is no longer a significant risk factor for perioperative mortality or reduced survival following elective repair of large asymptomatic AAA.

Straw S; Waduud MA; Drozd M; Warman P; Bailey MA; Hammond CJ; Abdel-Rahman S; Witte KK; Scott D;

Annals of the Royal College of Surgeons of England [Ann R Coll Surg Engl] 2020 Apr 01, pp. 1-8. Date of Electronic Publication: 2020 Apr 01.

Introduction: Cardiopulmonary exercise testing (CPET) and transthoracic echocardiography (TTE) are common preparative investigations prior to elective endovascular aneurysm repair (EVAR). Whether these investigations can predict survival following EVAR and contribute to shared decision making is unknown.
Methods: Patients who underwent EVAR at a tertiary centre between June 2007 and December 2014 were identified from the National Vascular Registry. Variables obtained from preoperative investigations were assessed for their association with survival at three years. Regression analysis was used to determine variables that independently predicted survival at three years.
Results: A total of 199 patients underwent EVAR during the study period. Of these, 120 had preoperative CPET and 123 had TTE. Lower forced expiratory ventilation (FEV ₁ ), ratio of FEV ₁ to forced vital capacity, work at peak oxygen consumption and higher ventilatory equivalent for carbon dioxide were associated with increased mortality. Variables obtained from TTE were not associated with survival at three years although there was a low incidence of left ventricular systolic dysfunction and significant valvular disease in this cohort.
Conclusions: CPET might be a useful adjunct to assist in shared decision making in patients undergoing elective EVAR and may influence anaesthetic technique. TTE does not appear to be able to discriminate between high and low risk individuals. However, a low rate of significant ventricular dysfunction and valvular disease in patients undergoing elective EVAR may account for these findings.

Eckerström F; Rex CE; Maagaard M; Heiberg J; Rubak S; Redington A; Hjortdal VE;

International journal of cardiology [Int J Cardiol] 2020 Feb 27. Date of Electronic Publication: 2020 Feb 27.

Background: There are increasing reports of cardiac and exercise dysfunction in adults with small, unrepaired ventricular septal defects (VSDs). The primary aim of this study was to evaluate pulmonary function in adults with unrepaired VSDs, and secondly to assess the effects of 900 μg salbutamol on lung function and exercise capacity.
Methods: Young adult patients with small, unrepaired VSDs and healthy age- and gender-matched controls were included in a double-blinded, randomised, cross-over study. Participants underwent static and dynamic spirometry, impulse oscillometry, multiple breath washout, diffusion capacity for carbon monoxide, and ergometer bicycle cardiopulmonary exercise test.
Results: We included 30 patients with VSD (age 27 ± 6 years) and 30 controls (age 27 ± 6 years). Patients tended to have lower FEV ₁ , 104 ± 11% of predicted, compared with healthy controls, 110 ± 14% (p = 0.069). Furthermore, the patient group had lower peak expiratory flow (PEF), 108 ± 20% predicted, compared with the control group, 118 ± 17% (p = 0.039), and showed tendencies towards lower forced vital capacity and increased airway resistance compared with controls. During exercise, the patients had lower oxygen uptake, 35 ± 8 ml/min/kg (vs 47 ± 7 ml/min/kg, p < 0.001), minute ventilation, 1.5 ± 0.5 l/min/kg (vs 2.1 ± 0.3 l/min/kg, p < 0.001) and breath rate, 48 ± 11 breaths/min (vs 55 ± 8 breaths/min, p = 0.008), than controls.
Conclusion: At rest, young adults with unrepaired VSDs are no different in pulmonary function from controls. However, when the cardiorespiratory system is stressed, VSD patients demonstrate significantly impaired minute ventilation and peak oxygen uptake, which may be early signs of parenchymal dysfunction and restrictive airway disease. These abnormalities were unaffected by the inhalation of salbutamol.

Chiu KL; Hsieh PC; Wu CW; Tzeng IS; Wu YK; Lan CC;

Heart & lung : the journal of critical care [Heart Lung] 2020 Mar 18. Date of Electronic Publication: 2020 Mar 18.

Background: How respiratory muscle strength influences the effectiveness of pulmonary rehabilitation (PR) in patients with chronic obstructive pulmonary disease (COPD) is unclear.
Objective: To investigate the benefits of PR in subjects with COPD according to respiratory muscle strength.
Methods: Ninety-seven subjects with COPD were evaluated using maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), pulmonary function tests, the cardiopulmonary exercise test (CPET), and the St. George’s Respiratory Questionnaire (SGRQ). Subjects were divided into four groups: 1 (normal MIP and MEP); 2 (low MIP); 3 (low MEP); and 4 (low MIP and MEP). Subjects underwent PR for 3 months; MIP, MEP, SGRQ, and CPET were evaluated post-PR.
Results: Subjects with both poor MIP and MEP had the highest dyspnea score, lowest exercise capacity, and poorest health-related quality of life (HRQoL). PR improved exercise capacity and HRQoL in all groups, with more improvement in MIP, MEP, tidal volume (on exercise), and dyspnea (at rest) in subjects with both low MIP and MEP.
Conclusions: Patients with respiratory muscle weakness had worse dyspnea, lower exercise capacity, and poorer HRQoL at baseline. Exercise training improved respiratory muscle strength with concurrent improvement of exercise capacity, HRQoL, and dyspnea score. Subjects with both poor baseline MIP and MEP showed greater benefits of PR.

Wagoner CW; Hanson ED; Ryan ED; Brooks R; Wood WA; Jensen BC; Lee JT;
Coffman EM; Battaglini CL.

Applied Physiology, Nutrition, & Metabolism = Physiologie Appliquee,
Nutrition et Metabolisme. 44(11):1159-1164, 2019 Nov.
VI 1

It is not uncommon for sedentary individuals to cite leg fatigue as the
primary factor for test termination during a cardiopulmonary exercise test
(CPET) on a cycle ergometer. The purpose of this study was to examine the
effect of 2 weeks of lower body resistance training (RT) on
cardiopulmonary capacity in sedentary middle-aged females. Additionally,
the impact of RT on muscle strength was evaluated.
Following familiarization, 28 women (18 exercise group, 10 control group) completed
a maximal CPET on a cycle ergometer to determine peak oxygen uptake and
leg extensor strength assessed using isokinetic dynamometry. Participants
in the exercise group performed 2 weeks (6 sessions) of lower body RT,
which comprised leg press, leg curl, and leg extension exercises.
A 2-way repeated-measures ANOVA was used to evaluate the difference in changes of
peak oxygen uptake and peak torque (PT). Peak oxygen uptake significantly
improved from 22.2 +/- 4.5 mL.kg-1.min-1 to 24.3 +/- 4.4 mL.kg-1.min-1
(10.8%, p < 0.05) as well as PT from 83.1 +/- 25.4 Nm to 89.0 +/- 29.7 Nm
(6.1%, p < 0.05) in the exercise group with no change in the control
group.
These findings provide initial evidence that 2 weeks of lower body
RT prior to a CPET may be a helpful preconditioning strategy to achieve a
more accurate peak oxygen uptake during testing, enhancing tolerability to
a CPET by improving lower body strength.

Takayanagi Y; Koike A; Kubota H; Wu L; Nishi I; Sato A; Aonuma K; Kawakami
Y; Ieda M.

Drug Discoveries & Therapeutics. 14(1):21-26, 2020 Mar 08.
VI 1

The pulse wave transit time (PWTT) is easily measured as the time from the
R wave of an electrocardiogram to the arrival of the pulse wave measured
by an oxygen saturation monitor at the earlobe. We investigated whether
the change of PWTT during exercise testing reflects cardiopulmonary
function. Eighty-nine cardiac patients who underwent cardiopulmonary
exercise testing (CPX) were enrolled. We analyzed the change of PWTT
during exercise and the relationship between the shortening of the PWTT
and CPX parameters. PWTT was significantly shortened from rest to peak
exercise (204.6 +/- 33.6 vs. 145.6 +/- 26.4 msec, p < 0.001) in all of the
subjects. The patients with heart failure had significantly higher PWTT at
peak exercise than the patients without heart failure (152.7 +/- 27.1 vs.
140.4 +/- 24.8 msec, p = 0.031). The shortening of PWTT from rest to peak
exercise showed significant positive correlations with the peak O2 uptake
(VO2) (r = 0.56, p < 0.001), anaerobic threshold (r = 0.40, p = 0.016),
and % increase of systolic blood pressure during exercise (r = 0.75, p <
0.001), and a negative correlation with the slope of the increase in
ventilation versus the increase in CO2 output (VE-VCO2 slope) (r = – 0.42,
p = 0.010) in the patients with heart failure. PWTT was shortened during
exercise as the exercise intensity increased. In the patients with heart
failure, the shortening of PWTT from rest to peak exercise was smaller in
those with lower exercise capacity and those with higher VE-VCO2 slope, an
established index known to reflect the severity of heart failure.

Hedman, K; Lindow, T; Elmberg, V; Brudin, L; Ekstrom, M.

Eur J Prev Cardiol. 2020:2047487320909667.  Link to actual article.
https://journals.sagepub.com/doi/full/10.1177/2047487320909667

BACKGROUND: Guidelines recommend considering workload in interpretation of the systolic blood pressure (SBP) response to exercise, but reference values are lacking.
DESIGN: This was a retrospective, consecutive cohort study.
METHODS: From 12,976 subjects aged 18-85 years who performed a bicycle ergometer exercise test at one centre in Sweden during the years 2005-2016, we excluded those with prevalent cardiovascular disease, comorbidities, cardiac risk factors or medications. We extracted SBP, heart rate and workload (watt) from >/= 3 time points from each test. The SBP/watt-slope and the SBP/watt-ratio at peak exercise were calculated. Age- and sex-specific mean values, standard deviations and 90th and 95th percentiles were determined. Reference equations for workload-indexed and peak SBP were derived using multiple linear regression analysis, including sex, age, workload, SBP at rest and anthropometric variables as predictors.
RESULTS: A final sample of 3839 healthy subjects (n = 1620 female) were included. While females had lower mean peak SBP than males (188 +/- 24 vs 202 +/- 22 mmHg, p < 0.001), workload-indexed SBP measures were markedly higher in females; SBP/watt-slope: 0.52 +/- 0.21 versus 0.41 +/- 0.15 mmHg/watt (p < 0.001); peak SBP/watt-ratio: 1.35 +/- 0.34 versus 0.90 +/- 0.21 mmHg/watt (p < 0.001). Age, sex, exercise capacity, resting SBP and height were significant predictors of the workload-indexed SBP parameters and were included in the reference equations. CONCLUSIONS: These novel reference values can aid clinicians and exercise physiologists in interpreting the SBP response to exercise and may provide a basis for future research on the prognostic impact of exercise SBP. In females, a markedly higher SBP in relation to workload could imply a greater peripheral vascular resistance during exercise than in males.

van der Ven JPG, Alsaied T, Juggan S, Bossers SSM, van den Bosch E, Kapusta L, Kuipers IM, Kroft LJM, Ten Harkel ADJ, van Iperen GG, Rathod RH, Helbing WA.

Int J Cardiol. 2020 Feb 24. pii: S0167-5273

OBJECTIVE: To assess the role of atrial function on exercise capacity and
clinical events in Fontan patients.
DESIGN: We included 96 Fontan patients from 6 tertiary centers, aged 12.8 (IQR
10.1-15.6) years, who underwent cardiac magnetic resonance imaging and
cardiopulmonary exercise testing within 12 months of each other from 2004 to
2017. Intra-atrial lateral tunnel (ILT) and extracardiac conduit (ECC) patients
were matched 1:1 with regard to age, gender and dominant ventricle. The pulmonary
venous atrium was manually segmented in all phases and slices. Atrial function
was assessed by volume-time curves. Furthermore, atrial longitudinal and
circumferential feature tracking strain was assessed. We determined the relation
between atrial function and exercise capacity, assessed by peak oxygen uptake and
VE/VCO2 slope, and events (mortality, listing for transplant, re-intervention,
arrhythmia) during follow-up.
RESULTS: Atrial maximal and minimal volumes did not differ between ILT and ECC
patients. ECC patients had higher reservoir function (21.1 [16.4-28.0]% vs 18.2
[10.9-22.2]%, p = .03), lower conduit function and lower total circumferential
strain (13.8 ± 5.1% vs 18.0 ± 8.7%, p = .01), compared to ILT patients. Only for
ECC patients, a better late peak circumferential strain rate predicted better
VE/VCO2 slope. No other parameter of atrial function predicted peak oxygen uptake
or VE/VCO2 slope. During a median follow-up of 6.2 years, 42 patients reached the
composite end-point. No atrial function parameters predicted events during
follow-up.
CONCLUSIONS: ECC patients have higher atrial reservoir function and lower conduit
function. Atrial function did not predict exercise capacity or events during
follow-up.

Fritz C; Muller J; Oberhoffer R; Ewert P; Hager A

Methods

After a lung function and cardiopulmonary exercise test (CPET), 42 Fontan patients (50% female; 30.5 ± 8.1 years) were randomized into either an intervention group (IG), or a control group (CG). The IG performed a telephone-supervised, daily IMT of three sets with 10–30 repetitions for six months.

Results

After six months of IMT, the IG did not improve in any exercise and lung capacity parameter compared to CG. VO₂peak (ΔVO₂peak: IG: 0.05 [−1.53; 1.33] ml/kg/min vs. CG: −0.50 [−1.20; 0.78] ml/kg/min; p = .784) and FVC (ΔFVC: IG: 0.07 [−0.16; 0.22] l vs. CG:−0.05 [−0.24; 0.18] l; p = .377) remained unchanged, while FEV1 trended to improve (ΔFEV₁: IG: 0.05 [−0.07; 0.13] l vs. CG: −0.10 [−0.19; 0.03] l; p = .082). Only oxygen saturation at rest improved significantly (ΔSpO₂: IG: 1.50 [−0.25; 3.00] % vs. CG: −0.50 [−1.75; 0.75] %; p = .017).