Nose-down saddle tilt improves gross efficiency during seated uphill cycling

Riding uphill presents a challenge to competitive and recreational cyclists. Based on only limited evidence, some scientists have reported that tilting the saddle nose down improves uphill-cycling efficiency by as much as 6%. Purpose: Here, we investigated if simply tilting the saddle nose down increases efficiency during uphill cycling, which would presumably improve performance. Methods: Nineteen healthy, recreational cyclists performed multiple 5-min trials of seated cycling at ~3 W kg–1 on a large, custom-built treadmill inclined to 8° under two saddle-tilt angle conditions: parallel to the riding surface and 8° nose down. We measured subjects’ rates of oxygen consumption and carbon dioxide production using an expired-gas analysis system and then calculated their average metabolic power during the last two min of each 5-min trial. Results: We found that, compared to the parallel-saddle condition, tilting the saddle nose down by 8° improved gross efficiency from 0.205 to 0.208 –– an average increase of 1.4 ± 0.2%, t = 5.9, p < .001, CI95% [0.9, 1.9], ES = 1.3. Conclusion: Our findings are relevant to competitive and recreational cyclists and present an opportunity for innovating new devices and saddle designs that enhance uphill cycling efficiency. The effect of saddle tilt on other slopes and the mechanism behind the efficiency improvement remain to be investigated.

Using metabolic energy to quantify the subjective value of physical effort

Economists have known for centuries that to understand an individual's decisions, we must consider not only the objective value of the goal at stake, but its subjective value as well. However, achieving that goal ultimately requires expenditure of effort. Surprisingly, despite the ubiquitous role of effort in decision-making and movement, we currently do not understand how effort is subjectively valued in daily movements. Part of the difficulty arises from the lack of an objective measure of effort. Here, we use a physiological approach to address this knowledge gap. We quantified objective effort costs by measuring metabolic cost via expired gas analysis as participants performed a reaching task against increasing resistance. We then used neuroeconomic methods to quantify each individual's subjective valuation of effort. Rather than the diminishing sensitivity observed in reward valuation, effort was valued objectively, on average. This is significantly less than the near-quadratic sensitivity to effort observed previously in force-based motor tasks. Moreover, there was significant inter-individual variability with many participants undervaluing or overvaluing effort. These findings demonstrate that in contrast with monetary decisions in which subjective value exhibits diminishing marginal returns, effort costs are valued more objectively in low-effort reaching movements common in daily life.

Cooper’s 12 min run test: Its validity in Indian swimmers and volleyball players

Objectives: VO2max is globally considered as the gold standard to evaluate the cardiorespiratory fitness that is an essential component to judge one’s aerobic fitness level. The present study was aimed to enumerate the validity for application of Cooper’s 12 min run test (CRT) in predicting VO2max among Indian swimmers and volleyball players. Materials and Methods: Swimmers (male = 66, female = 70) and volleyball players (male = 88, female = 81) were recruited by simple random sampling from reputed clubs of Kolkata. They were segregated into study and confirmatory groups. VO2max was determined by graded incremental cycle ergometer test followed by expired gas analysis and indirect CRT method. Results: Predicted VO2max (PVO2max) showed significant difference with the directly measured VO2max (VO2max) in study groups of both sports. Limits of agreement between PVO2max and VO2max proved inapplicability of current CRT protocol in studied populations. Modified population specific equations were computed from significant correlation of VO2max with distance covered in Cooper run test. Application of these norms in confirmatory groups revealed insignificant difference between PVO2max and VO2max in both genders. Conclusion: Modified equations are validated for application of CRT in evaluating VO2max in swimmers and volleyball players of both genders of Kolkata, India.

Novel noninvasive estimation of mixed venous oxygen saturation by echocardiography and expired gas analysis

Clinical use of mixed venous oxygen saturation ([Formula: see text]) is limited for the required invasive procedure. With Fick’s equation, expired gas analysis, echocardiography, simple blood tests, and percutaneous oxygen saturation, [Formula: see text] can be calculated noninvasively. We hypothesized that noninvasively calculated [Formula: see text] shows a significant correlation and agrees well with invasively measured [Formula: see text]. The present study examined the relationship between measured [Formula: see text] and calculated [Formula: see text] in patients who underwent right heart catheterization and demonstrated acceptable agreement. This novel method can expand the indication of evaluating [Formula: see text].

Protocols of exercise testing in athletes and cardiopulmonary testing: assessment of fitness

Exercise and cardiopulmonary exercise testing are essential in the evaluation of the cardiovascular response to exercise. They are clinically used to evaluate the subject’s capacity to tolerate increasing work loads. Throughout the tests electrocardiographic, haemodynamic, and symptomatic responses are monitored to assess ischaemic, hypertensive, and arrhythmic manifestations of disease. Ventilatory expired gas analysis may also be performed, as it provides fundamental information, particularly in patients with congestive heart failure or other exercise-induced limitations.

Cardiopulmonary Exercise Testing

The chapter Cardiopulmonary Exercise Testing focuses on the opportunities provided by cardiopulmonary exercise (CPX) testing. The coordination of 5 organ systems is described in normal exercise physiology to understand abnormal exercise findings. From a few measured expired gas analysis parameters, most of the important exercise variables can be derived, including the peak oxygen consumption (peak VO2). The contribution of both the aerobic and anaerobic phases of exercise to total exercise capacity are described, including the methods for determination of the anaerobic threshold. The calculation of the normative values of peak VO2 are included, and a suggested template of a CPX report is included. The use of CPX testing in the determination of prognosis in heart failure patients is included.