Submaximal oxygen uptake efficiency slope as a predictor of VO2max in men with cardiovascular disease

Purpose: Although V̇O2 max is considered the gold standard measure of cardiorespiratory fitness (CRF), it can be difficult to attain in patients with cardiovascular disease (CVD). The submaximal oxygen uptake efficiency slope (OUES) integrates cardiovascular, musculoskeletal and respiratory function during incremental exercise into a single index and has been proposed as an alternative and effort independent measure of cardiopulmonary reserve (Baba et al., 1996). The purpose of this study was to examine the relation between V̇O2 max and both submaximal absolute OUES and relative OUES (OUES.kg-1). Methods: A total of 55 men ((mean ± SD) age, 59.08 ± 9.03 yr; VO2 max, 1.94 ± 0.53 L.min-1and 22.73 ± 5.95 mL.kg-1.min-1) were recruited during induction to a community based exercise referral program following completion of phase 2 cardiac rehabilitation. Participants performed a graded exercise test on a cycle ergometer with breath-by-breath open circuit spirometry and a 12 lead ECG. Absolute OUES and OUES.kg-1 were calculated by plotting VO2 in mL.min-1 on the x-axis, and the log transformed VE on the y-axis (VO2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold (VAT) was included in the analysis. Results: The %V̇O2 max corresponding to the VAT was 55.72 ± 11.81. Absolute OUES and OUES.kg-1 were 2164.42 ± 540.96 and 25.28 ± 5.99, respectively. There was a significant positive correlation between V̇O2 max (L.min-1) and OUES (r= 0.775; p<0.001) and between V̇O2 max (mL.kg-1.min-1) and OUES.kg-1 (r= 0.78; p<0.001). Conclusion: Determination of V̇O2 max is not often feasible in individuals with CVD where maximal exercise testing is contraindicated or when performance may be impaired by pain, dyspnea or angina. The findings from the present study indicate that the OUES and OUES.kg-1 are significantly related to absolute and relative V̇O2 max, respectively and may be used as a valid sub maximal effort independent measure of CRF

Active commuting to school: How far is too far?

Walking and cycling to school provide a convenient opportunity to incorporate physical activity into an adolescent's daily routine. School proximity to residential homes has been identified as an important determinant of active commuting among children. The purpose of this study is to identify if distance is a barrier to active commuting among adolescents, and if there is a criterion distance above which adolescents choose not to walk or cycle. Data was collected in 2003-05 from a cross-sectional cohort of 15-17 yr old adolescents in 61 post primary schools in Ireland. Participants self-reported distance, mode of transport to school and barriers to active commuting. Trained researchers took physical measurements of height and weight. The relation between mode of transport, gender and population density was examined. Distance was entered into a bivariate logistic regression model to predict mode choice, controlling for gender, population density socio-economic status and school clusters. Of the 4013 adolescents who participated (48.1% female, mean age 16.02 ± 0.661), one third walked or cycled to school. A higher proportion of males than females commuted actively (41.0 vs. 33.8%, χ2 (1) = 22.21, p < 0.001, r = -0.074). Adolescents living in more densely populated areas had greater odds of active commuting than those in the most sparsely populated areas (χ2 (df = 3) = 839.64, p < 0.001). In each density category, active commuters travelled shorter distances to school. After controlling for gender and population density, a 1-mile increase in distance decreased the odds of active commuting by 71% (χ2 (df = 1) = 2591.86, p < 0.001). The majority of walkers lived within 1.5 miles and cyclists within 2.5 miles. Over 90% of adolescents who perceived distance as a barrier to active commuting lived further than 2.5 miles from school. Distance is an important perceived barrier to active commuting and a predictor of mode choice among adolescents. Distances within 2.5 miles are achievable for adolescent walkers and cyclists. Alternative strategies for increasing physical activity are required for individuals living outside of this criterion

Relation between physical activity and oxygen uptake efficiency in men with CVD

Purpose: The oxygen uptake efficiency slope (OUES) represents the rate of increase in V̇O2 in response to a given V̇E during incremental exercise, indicating how effectively oxygen is taken in by the lungs, transported and used in the periphery. OUES, calculated using only submaximal exercise data is identical to the OUES calculated over the entire duration of a cardiopulmonary exercise test (CEPT) , and both maximal and submaximal OUE are significantly related to cardiorespiratory fitness (CRF) measured as V̇O2peak. Currently, little research has been published on how physical activity (PA) assessed by accelerometers is related to submaximal and maximal OUES. The purpose of this study was to determine the relation light (LIPA), moderate (MIPA) and vigorous (VIPA) intensity physical activity and maximal and submaximal OUES in men with cardiovascular disease (CVD). Methods: A total of 56 men (mean ( SD): age of 59.3 ± 9.2 yr., V̇O2 peak (L/min) 2.0 0.50, V̇O2 peak (mL/kg/min) 23.6 5.8, were recruited during an induction to a community-based exercise referral program following completion of phase 2 cardiac rehabilitation program. Participants underwent a graded exercise test on a cycle ergometer with breath by breath open circuit spirometry after which they wore a wrist worn accelerometer (Actigraph) for 7 d. Absolute and relative submaximal and maximal OUES were calculated by plotting V̇O2 in mL/min on the x axis, and the log transformed VE on the y axis (V̇O2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold and maximal exercise were used to calculate submaximal and maximal OUE, respectively. Results: Participants performed 584.49 73.87 min of daily LIPA, 145.45 60.85 min of MIPA and no daily min of VIPA. There was a significant relation between absolute submaximal OUES (r=0.386; p<0.01), submaximal OUES/Kg (r=0.296; p<0.05) and LIPA. There was a significant relation between maximal OUES (r=0.286; p<0.05), maximal OUES/Kg (r=0.279; p<0.05) and MIPA. Conclusion: Submaximal and maximal OUE are related to levels of LIPA and MIPA, respectively. Submaximal OUES can potentially be used as an objective, effort independent test to estimate LIPA levels among men with CVD

Physical activity patterns and cardiorespiratory fitness in men with cardiovascular disease

Purpose: Cardiorespiratory fitness (CRF) is generally regarded as an objective and reproducible measure of recent habitual physical activity (PA). Considering that the majority of daily PA is performed at light intensity, it is likely that CRF benefits will be detected at submaximal rather than maximal exercise. The purpose of this study was to evaluate daily minutes of light (LIPA), moderate (MIPA) and vigorous (VIPA) intensity physical activity among men with cardiovascular disease (CVD), and to determine the relation between PA and submaximal (oxygen uptake efficiency slope (OUES)) and maximal (V̇O2 peak) indices of CRF. Methods: A total 32 male participants (mean ( SD): age of 60.0 ± 8.7 yr, V̇O2 peak (L/min) 2.0 0.45, V̇O2 peak (mL/kg/min) 23.3 5.7, were recruited during an induction to a community based exercise referral program following completion of phase 2 cardiac rehabilitation. Participants underwent a graded exercise test on a cycle ergometer with breath by breath open circuit spirometry after which they wore a wrist worn accelerometer (Actigraph) for 7 d. Absolute and relative submaximal OUES were calculated by plotting V̇O2 in mL/min on the x axis, and the log transformed VE on the y axis (V̇O2 = a log 10 VE + b). Exercise data up to the ventilatory anaerobic threshold was included in the analysis. Results: Participants performed 589.05 69.41 min of daily LIPA, 161.38 66.16 min of MIPA and no daily min of VIPA. There was no significant relation between peak V̇O2 and either LIPA or MIPA. There was a significant correlation between submaximal OUES (r=0.44; p<0.01) and LIPA. The relation between submaximal OUES/kg and LIPA min almost reached statistical significance (r=0.33; p<0.07). There was no significant relation between MIPA and OUES or OUES/kg. Conclusion: Men with CVD spend the majority (78%) of their day performing LIPA. OUES, a submaximal measure of CRF was related LIPA whereas no relation was found between V̇O2 peak and LIPA

Exploration of physical activity knowledge, preferences and support needs among pulmonary hypertension patients

Objective: Physical activity (PA) is an established adjunct therapy for pulmonary hypertension (PH) patients to mitigate PH symptoms and improve quality of life. However, PA engagement within this population remains low. This study investigated PH patients’ knowledge of PA, recalled advice, exercise preferences and PA support needs. Methods: Semi-structured interviews were conducted with 19 adults (mean age 50 years; SD ±12 years) diagnosed with PH, living in Ireland. Interview scripts were digitally recorded and transcribed verbatim. Thematic analysis was used to analyse the data. Results: Four key themes were identified: Lack of PA knowledge; exercise setting preference; accountability and monitoring; and clinician delivered PA information and guidance. Conclusion: This study found that PH clinicians provide suboptimal PA advice, yet patients desired clinician-delivered PA guidance. Home-based exercise was preferred with monitoring and external accountability deemed as important to facilitate sustained engagement. Practice implications: PH clinicians are well positioned to play a critical role in assisting and empowering PH patients to engage in PA. Providing training and education to PH clinicians regarding exercise prescription may be beneficial. Further research is needed to evaluate the feasibility and efficacy of home-based exercise interventions to improve quality of life and physical activity in PH

Platelets: From Formation to Function

Platelets are small, anucleate cells that travel as resting discoid fragments in the circulation. Their average circulating life span is 8–9 days, and their formation is an elegant and finely orchestrated series of cellular processes known as megakaryocytopoiesis and thrombopoiesis. This involves the commitment of haematopoietic stem cells, proliferation, terminal differentiation of megakaryocytic progenitors and maturation of megakaryocytes to produce functional platelets. This complex process occurs in specialised endosteal and vascular niches in the bone marrow where megakaryocytes form proplatelet projections, releasing platelets into the circulation. Upon contact with an injured blood vessel, they prevent blood loss through processes of adhesion, activation and aggregation. Platelets play a central role in cardiovascular disease (CVD), both in the development of atherosclerosis and as the cellular mediator in the development of thrombosis. Platelets have diverse roles not limited to thrombosis/haemostasis, also being involved in many vascular inflammatory conditions. Depending on the physiological context, platelet functions may be protective or contribute to adverse thrombotic and inflammatory outcomes. In this chapter, we will discuss platelets in context of their formation and function. Because of their multifaceted role in maintaining physiological homeostasis, current and development of platelet function testing platforms will be discussed

Safety, Feasibility and Effectiveness of the remotely delivered Pulmonary Hypertension And Home-Based (PHAHB) Physical Activity intervention

Background Pulmonary hypertension (PH) is a heterogeneous condition, associated with a high symptom burden and a substantial loss of exercise capacity. Despite prior safety concerns regarding physical exertion, exercise training as a supportive therapy is now recommended for PH patients. Currently, most programs are hospital-based, which limits accessibility. There is a need to provide alternative approaches for physical activity engagement for PH patients. The aim of this research was to develop, implement and evaluate the safety, feasibility, and effectiveness of home-based physical activity intervention for PH. Methods An entirely remotely delivered home-based exercise intervention underpinned by behaviour change theory and informed by end-users, was assessed using a single-arm feasibility study design. Participants (n=19; 80% female) with a mean (±sd) age of 49.9±15.9 y with a diagnosis of PH undertook a 10-week, home-based exercise intervention with induction training, support materials, telecommunication support, health coaching, exercise training, and assessments, all remotely delivered. Training involved respiratory training along with a combination of aerobic and resistance exercises. Results The intervention was deemed safe as no adverse events were reported. A high level of feasibility was demonstrated as the protocol was implemented as intended, sustained a high level of engagement and adherence and was well accepted by participants in terms of enjoyment and utility. There was a significant improvement in functional capacity, physical activity, exercise self-efficacy and quality of life (QoL), between baseline and post-training. Conclusion The study demonstrates that an entirely remotely delivered home-based exercise program is safe, feasible and effective in improving functional capacity, physical activity, and QoL in PH patients

PPAR alpha L162V underlies variation in serum triglycerides and subcutaneous fat volume in young males

Background: Of the five sub-phenotypes defining metabolic syndrome, all are known to have strong genetic components ( typically 50 - 80% of population variation). Studies defining genetic predispositions have typically focused on older populations with metabolic syndrome and/or type 2 diabetes. We hypothesized that the study of younger populations would mitigate many confounding variables, and allow us to better define genetic predisposition loci for metabolic syndrome. Methods: We studied 610 young adult volunteers ( average age 24 yrs) for metabolic syndrome markers, and volumetric MRI of upper arm muscle, bone, and fat pre- and post-unilateral resistance training. Results: We found the PPARa L162V polymorphism to be a strong determinant of serum triglyceride levels in young White males, where carriers of the V allele showed 78% increase in triglycerides relative to L homozygotes ( LL = 116 +/- 11 mg/ dL, LV = 208 +/- 30 mg/ dL; p = 0.004). Men with the V allele showed lower HDL ( LL = 42 +/- 1 mg/ dL, LV = 34 +/- 2 mg/ dL; p = 0.001), but women did not. Subcutaneous fat volume was higher in males carrying the V allele, however, exercise training increased fat volume of the untrained arm in V carriers, while LL genotypes significantly decreased in fat volume ( LL = - 1,707 +/- 21 mm(3), LV = 17,617 +/- 58 mm(3); p = 0.002), indicating a systemic effect of the V allele on adiposity after unilateral training. Our study suggests that the primary effect of PPARa L162V is on serum triglycerides, with downstream effects on adiposity and response to training. Conclusion: Our results on association of PPARa and triglycerides in males showed a much larger effect of the V allele than previously reported in older and less healthy populations. Specifically, we showed the V allele to increase triglycerides by 78% ( p = 0.004), and this single polymorphism accounted for 3.8% of all variation in serum triglycerides in males ( p = 0.0037)

MC4R Variant Is Associated With BMI but Not Response to Resistance Training in Young Females

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93697/1/oby_2147_sm_1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/93697/2/oby.2010.180.pd