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This analysis of secondary outcomes investigated the applicability of supramaximal high-intensity interval training (HIT) with individually prescribed external intensity performed on stationary bicycles. Sixty-eight participants with a median (min; max) age of 69 (66; 79), at the time not engaged in regular exercise were randomized to 25 twice-weekly sessions of supramaximal HIT (20-min session with 10 × 6-s intervals) or moderate-intensity training (MIT, 40-min session with 3 × 8-min intervals). The primary aim was outcomes on applicability regarding; adherence to prescribed external interval intensity, participant reported positive and negative events, ratings of perceived exertion (RPE 6–20), and affective state (Feeling Scale, FS -5–5). A secondary aim was to investigate change in exercise-related self-efficacy (Exercise Self-Efficacy Scale) and motivation (Behavioural Regulations in Exercise Questionnaire-2). Total adherence to the prescribed external interval intensity was [median (min; max)] 89 % (56; 100 %) in supramaximal HIT, and 100 % (95; 100 %) in MIT. The supramaximal HIT group reported 60 % of the positive (112 of 186) and 36 % of the negative (52 of 146) events. At the end of the training period, the median (min; max) session RPE was 15 (12; 17) for supramaximal HIT and 14 (9; 15) for MIT. As for FS, the median last within-session rating was 3 (−1; 5) for supramaximal HIT and 3 (1; 5) for MIT. Exercise-related motivation increased (mean difference in Relative Autonomy Index score = 1.54, 95 % CI [0.69; 2.40]), while self-efficacy did not change (mean difference = 0.55, 95 % CI [-0.75; 1.82]), regardless of group. This study provide support for supramaximal HIT in supervised group settings for older adults.

OBJECTIVE: This study investigated the effectiveness of supramaximal high-intensity interval training (supramaximal HIT) on muscle capacities and physical function compared to moderate-intensity training (MIT) for older adults.

METHODS: Sixty-eight older adults (66-79 years, 56% women), not engaged in regular exercise, were randomised to 3 months of twice-weekly supramaximal HIT (20 minutes including 10 × 6-second intervals) or MIT (40 minutes including 3 × 8-minute intervals). Both groups performed the training on stationary bicycles in a group setting. Target intensity was watt-controlled, with standardised cadence and individualised resistance. Outcomes analysed with linear-mixed models included leg power (Nottingham Power Rig), hand grip strength (Jamar dynamometer), static and dynamic balance (One leg stance, 30-second step test), chair stand (30-second chair stand), and anaerobic cycling performance (modified Borg Cycle Strength Test).

RESULTS: Baseline values were (supramaximal HIT/MIT, mean ± SD) leg power 198 ± 60/189 ± 53 W, hand grip strength 4.2 ± 1.0/4.3 ± 1.1 N/kg, static balance 64 ± 41/62 ± 41 s, dynamic balance 39 ± 7/38 ± 5 steps, chair stands 22 ± 6/22 ± 6 and anaerobic cycling performance 224 ± 60/217 ± 55 W. At 3-month follow-up, a between-group difference in favour of supramaximal HIT [95% CI] was observed in anaerobic cycling performance of 19[3;35] W. Within-group mean changes for supramaximal HIT/MIT were for leg power 8.4[0.9;15.8]/6.0[-1.3;13.3] W, hand grip strength 0.14[0.00;0.27]/0.13[-0.01;0.26] N/kg, static balance 11[3;20]/10[1;18] s, dynamic balance 1.6[0.3;2.8]/2.3[1.1;3.6] steps, 2.1[1.1;3.1]/1.4[0.4;2.3] chair stands and anaerobic cycling performance 31.3[19.6;43.0]/12.0[0.4;23.5] W.

CONCLUSION: Supramaximal HIT showed superior effect on anaerobic cycling performance when compared to MIT. Additionally, the results indicate that supramaximal HIT is comparably beneficial as MIT in terms of effects on muscle capacity and physical function for older adults.

Background: Breathlessness is common in the population and can be related to a range of medical conditions. We aimed to evaluate the burden of breathlessness related to different medical conditions in a middle-aged population.

Methods: Cross-sectional analysis of the population-based Swedish CArdioPulmonary bioImage Study of adults aged 50–64 years. Breathlessness (modified Medical Research Council [mMRC] ≥ 2) was evaluated in relation to self-reported symptoms, stress, depression; physician-diagnosed conditions; measured body mass index (BMI), spirometry, venous haemoglobin concentration, coronary artery calcification and stenosis [computer tomography (CT) angiography], and pulmonary emphysema (high-resolution CT). For each condition, the prevalence and breathlessness population attributable fraction (PAF) were calculated, overall and by sex, smoking history, and presence/absence of self-reported cardiorespiratory disease.

Results: We included 25,948 people aged 57.5 ± [SD] 4.4; 51% women; 37% former and 12% current smokers; 43% overweight (BMI 25.0–29.9), 21% obese (BMI ≥ 30); 25% with respiratory disease, 14% depression, 9% cardiac disease, and 3% anemia. Breathlessness was present in 3.7%. Medical conditions most strongly related to the breathlessness prevalence were (PAF 95%CI): overweight and obesity (59.6–66.0%), stress (31.6–76.8%), respiratory disease (20.1–37.1%), depression (17.1–26.6%), cardiac disease (6.3–12.7%), anemia (0.8–3.3%), and peripheral arterial disease (0.3–0.8%). Stress was the main factor in women and current smokers.

Conclusion: Breathlessness mainly relates to overweight/obesity and stress and to a lesser extent to comorbidities like respiratory, depressive, and cardiac disorders among middle-aged people in a high-income setting—supporting the importance of lifestyle interventions to reduce the burden of breathlessness in the population.

Introduction: Resistance training (RT) is a key component of pulmonary rehabilitation for people with COPD; however, whether the effects of RT could be optimized by utilizing the exercise principle of non-linear periodization is yet to be determined.

Method: An international multicenter RCT was conducted across three countries. Fifty-seven people with COPD (70+7 yrs, FEV1% 49+21, 58% male) were randomized to 8 weeks of RT designed per current COPD guidelines to improve muscle strength or to non-linear periodized resistance training (NLPRT) designed to improve muscle strength [4 weeks] but also muscle endurance [4 weeks]. Outcomes included muscle strength, muscle endurance, functional exercise capacity (1-minute sit-to-stand [1-STS], endurance shuttle walk test [ESWT], Unsupported Upper Limb Exercise test [UULEX]), and disease-specific quality of life (QoL). Intention-to-treat (ITT) analysis was utilized, and Cohen's D Effect Sizes [ES] were calculated.

Result: ITT analysis demonstrated that NLPRT resulted in more pronounced effects on muscle strength (+33% vs. +21%, ES 0.928), muscle endurance (+147% vs. +50%, ES 1.080), ESWT (+168m vs. +36m, ES 0.592), 1-STS (+4 STS vs. 1 STS, ES 0.864), UULEX (+142sec vs. + 42sec, ES=0.819) (all p<0.05) when compared to RT. Both NLPRT and RT resulted in clinically relevant improvements in QoL without differences between modalities.

Conclusion: These results indicate that 8 weeks of NLPRT yields significantly better outcomes in various dimensions of muscle function and functional capacity when compared to 8 weeks of traditional RT. Consequently, this suggests a potential need for reevaluating and updating current RT guidelines to incorporate these findings.

Introduction: The lack of reference values of lower-limb muscle function hinders the clinical recommendations of its measurement in patients with COPD. Therefore, this study aimed to develop reference equations to predict reference values for quadriceps strength, endurance and power and evaluate their construct validity in patients with COPD.

Methods: Quadriceps strength, endurance and power were assessed in 158 healthy individuals and 87 patients with COPD. In addition, patients with COPD performed a 6-min walk test (6MWT) and a 1-min sit-to-stand test (1STS). Multiple linear regressions were performed to develop reference equations. The proportion of patients with COPD with reduced quadriceps function was determined, and correlations between quadriceps strength, endurance and power expressed in percentage of predicted values and 6MWT and 1STS performance were used to document the construct validity of the reference equation.

Results: Except for quadriceps isometric endurance, the proposed reference equations explained 50-70% of the variance of the quadriceps properties in healthy individuals. All quadriceps properties were systematically reduced in a large proportion of patients with COPD compared to healthy individuals. Correlation coefficients between quadriceps properties expressed in percentage of predicted values and 6MWT and 1STS performance ranged between 0.28 and 0.49 (all p<0.05).

Conclusion: In healthy individuals, age, sex, height and body mass index explained 50-70% of the variance of quadriceps strength, endurance and power. When expressed in percentage of predicted values, these quadriceps properties correlated with 6MWT and 1STS performance, suggesting construct validity of the reference values in patients with COPD.

Knowledge about modifiable determinants of daily physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD) is crucial to design effective PA interventions. The present study aimed to determine the contribution of quadriceps strength, power and endurance to daily PA in COPD. Additionally, for quadriceps endurance, we also aimed to determine to what extent the association varies according to the mode of movement (isotonic, isometric, or isokinetic). Using a multicentre cross-sectional trial design we determined the contribution of quadriceps function to daily PA (steps, sedentary time and time spent doing moderate-to-very-vigorous physical activity [MVPA]) using bivariate and partial Pearson correlation analysis (r) and multiple linear regression models (ΔR2). Pre-determined controlling factors were sex, age, body mass index (BMI), COPD-assessment test, forced expiratory volume in one second in percent of the predicted value (FEV1pred), and distance walked on the 6-minute walk test. Eighty-one patients with COPD (mean ± SD: age 67 ± 8 years, FEV1pred 57 ± 19%, daily steps 4968 ± 3319, daily sedentary time 1016 ± 305 min, and MVPA time 83 ± 45 min) were included. Small to moderate bivariate correlations (r =.225 to.452, p <.05) were found between quadriceps function and measures of PA. The best multiple linear regression models explained 38–49% of the variance in the data. Isotonic endurance was the only muscle contributor that improved all PA models; daily steps (ΔR2 =.04 [relative improvement 13%] p =.026), daily sedentary time (ΔR2 =.07 [23%], p =.005) and MVPA-minutes (ΔR2 =.08 [20%], p =.001). Isotonic endurance was also independently associated with most PA variables, even when controlling for strength, power or isometric-isokinetic endurance properties of the muscle (r =.246 to.384, p <.05). In contrast, neither strength, power, isometric-or isokinetic endurance properties of the muscle was independently associated with PA measures when controlling for isotonic endurance (r =.037 to.219, p >.05). To conclude, strength, power, and endurance properties of the quadriceps were low to moderately associated with PA in patients with COPD. Isotonic quadriceps endurance was the only quadriceps property that was independently associated with the different measures of PA after controlling for a basic set of known determinants of PA, quadriceps strength or power, or isometric or isokinetic quadriceps endurance. Future longitudinal studies should investigate its potential as a modifiable determinant of PA.

OBJECTIVE: Various functional muscle properties affect different aspects of functional exercise capacity in people with COPD. The purpose of this study was to investigate the contribution of quadriceps muscle strength, endurance, and power to the 6-minute walking distance (6MWD) and the 1-minute sit-to-stand test (1STS) performance in people with COPD.

METHODS: The study was a prospective, multicenter cross-sectional study. Anthropometrics, Medical Research Council (MRC) dyspnea scale, lung function, 6MWD and the 1STS number of repetitions were assessed. Isometric quadriceps strength (Strength-ISOM) and endurance (Endurance-ISOM), isotonic quadriceps endurance (Endurance-ISOT), isokinetic quadriceps strength (Strength-ISOKIN), and power (Power-ISOKIN) were assessed on a computerized dynamometer while functional quadriceps power was determined during 5 sit-to-stand repetitions (Power-5STS). Univariate and multivariate analyses were performed to determine the contribution of functional muscle properties on the 6MWD and the 1STS number of repetitions.

RESULTS: The study included 70 people with COPD (mean % predicted FEV1 = 58.9 [SD = 18.2]). The 6MWD correlated with each functional muscle property, except the Endurance-ISOM. The number of repetitions during the 1STS correlated with each functional muscle property except isometric measurements. Multivariate models explained respectively 60% and 39% of the variance in the 6MWD and 1STS number of repetitions, with Power-5STS being the muscle functional property with the strongest contribution to the models.

CONCLUSION: Except for isometric endurance, quadriceps strength, endurance, and power were associated with functional exercise capacity in people with moderate COPD. Among these functional muscle properties, muscle power contributed the most to the 6MWD and 1STS number of repetitions, suggesting that muscle power is more relevant to functional exercise capacity than muscle strength or endurance in people with COPD.

IMPACT: Understanding the individual contribution of muscle properties to functional status is important to designing interventions. This study provides the guidance that muscle power may be more important to functional exercise capacity than muscle strength or endurance in people with COPD.

Chronic obstructive pulmonary disease (COPD) is a disease that is characterised by persistent respiratory symptoms and airflow limitation. Consequences beyond the airways and lungs are common, and include limb muscle dysfunction. Limb muscle dysfunction is treated with exercise training, and should be preceded by assessments to individualise prescriptions. Guidelines recommend assessment of quadriceps strength, but limb muscle dysfunction affects more than strength. Other less investigated assessments may be of interest. During training, direct physiological (cardiorespiratory, metabolic, and biomechanical) and symptomatic responses are important, since they can affect training effectivity, and they may differ depending on whether arms or legs are used. The main aims of this thesis were to investigate the relevance of assessments of quadriceps function, feasibility and reliability of methods to assess quadriceps endurance, and to compare the direct physiological and symptomatic responses during arm and leg activities in people with COPD.

Method: This thesis is based on four papers. These include one systematic review with a meta-analysis of studies comparing direct physiological and symptomatic responses to activities performed with the arms versus the legs, and three papers based on an international cross-sectional multicentre study investigating reliability, feasibility, and relevance of three leg extension assessments of quadriceps endurance. Relative and absolute reliability were determined via interclass correlation coefficient (ICC), coefficient of variation (CV %), and limits of agreement (LoA %) for measures of isokinetic total work, isokinetic fatigue index, isometric time to exhaustion, and isotonic repetitions to exhaustion. The relevance of the measures of quadriceps endurance and other quadriceps functions were determined by the association to functional capacity and physical activity with Pearson correlation analyses (r) and multiple linear regression models (R², adjusted R², Δ R², and Δ adjusted R²).

Results: Results from the meta-analyses show that leg-cycle ergometer resulted in greater tidal volume (137 mL), minute ventilation (4.8 L/min), and oxygen consumption (164 mL/min) compared to arm cycle ergometer, while symptomatic responses were similar. Physiological responses (e.g., minute ventilation and oxygen consumption) during arm compared to leg resistance training exercises were similar. Results from studies on functional activities depend on the type and intensity of the activity performed. Isokinetic total work was the measurement with the highest relative reliability (ICC = 0.98) and the smallest absolute reliability (e.g., CV% = 6.5). Isokinetic fatigue index, isometric, and isotonic measures demonstrated low-to-high relative reliability (ICC = 0.64, 0.88, 0.91), and absolute reliability was larger (e.g., CV% = 20.3, 14.9, and 15.8%). Participants performed better on the retest for isokinetic total work and isometric measurements (4.8 and 10%, p < 0.001). The feasibility was similar across protocols, with an average time consumption of< 7.5 minutes, limited perceived dyspnoea compared to leg fatigue, and no major adverse advents. The measures of quadriceps function had mostly similar (r = +/- 0.07–0.45) levels of correlations to the functional capacity and physical activity. In multiple regression analyses improved quadriceps power the models to predict functional capacity the most (Δ adjusted R²= 0.10, 0.15, adjusted R² = 0.60, 0.39). Isotonic endurance was the only muscle function that improved all physical activity models (ΔR² = 0.04–0.07, p < 0.05, R² = 0.38–0.49).

Conclusions: The results indicate that if the goal of an activity is to maximise physiological responses such as minute ventilation and oxygen consumption, activities involving the legs should be preferred. Symptomatic responses seems task and intensity dependent, which suggest that strategies used to reduce symptoms should be based on relative intensity. In the assessment of quadriceps endurance, isokinetic, isometric and isotonic protocols present low to very high relative reliability. Differences in reliability and the better performance at retest might reflect differences in ability to detect true change. Quadriceps power seems to be more relevant to functional capacity, and isotonic quadriceps endurance seems to be more relevant to physical activity.

Introduction: It is commonly known that quadriceps muscle endurance is decreased among people with COPD, however, whether static and dynamic quadriceps muscle endurance is affected to the same extent, remains to be determined. The latter of importance for the design of exercise modalities targeting quadriceps endurance in COPD.Methods: Static (isometric) and dynamic (isokinetic, isotonic) measurements of quadriceps muscle endurance was performed using a computerized dynamometer on 30 of individuals with COPD (FEV1 63% predicted) and 30 healthy age and gender-matched controls. Test order was randomized, separated by 30 min of rest. Comparisons between groups included both relative (seconds/repetitions) and absolute (total work [Nm]) measures of quadriceps endurance. Between-group results are presented as percentage difference (%) and effect sizes (ES).Results: When compared to healthy age and gender matched controls, people with COPD had significantly lower absolute measures of quadriceps endurance (isometric -32%, ES 0.66 [moderate]; isokinetic -29%, ES 0.94 [large], isotonic -38%, ES 0.89 [large], all p &lt;0.05) as well as lower relative measures of dynamic quadriceps endurance (isotonic [repetitions] -20%, ES 0.50 [moderate], p = 0.02) while static quadriceps endurance did not differ between groups (isometric [seconds] -3%, ES 0.06 [trivial], p = 0.617).Conclusion: As evident by larger ES, dynamic quadriceps endurance seems to be reduced to a larger extent than static quadriceps endurance in people with COPD. Thus, exercise modalities that aim to improve quadriceps endurance should preferably be designed to increase dynamic quadriceps muscle enduranceFootnotesCite this article as: European Respiratory Journal 2019; 54: Suppl. 63, OA3814.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).