Exercise endurance time as a function of percent maximal power production

1987 ◽  
Vol 19 (5) ◽  
pp. 480???485 ◽  
Author(s):  
EVERETT A. HARMAN ◽  
HOWARD G. KNUTTGEN ◽  
PETER N. FRYKMAN ◽  
JOHN F. PATTON
1990 ◽  
Vol 60 (3) ◽  
pp. 222-227 ◽  
Author(s):  
J. F. Patton ◽  
W. J. Kraemer ◽  
H. G. Knuttgen ◽  
E. A. Harman

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
John Mativo ◽  
Kevin Hallinan ◽  
Uduak George ◽  
Greg Reich ◽  
Robin Steininger

Abstract Typical thermoelectric generator legs are brittle which limits their application in vibratory and shear environments. Research is conducted to develop compliant thermoelectric generators (TEGs) capable of converting thermal loads to power, while also supporting shear and vibratory loads. Mathematical structural, thermal, and power conversion models are developed. Topology optimization is employed to tailor the TEG design yield maximal power production while sustaining the applied shear and vibratory loads. As a specific example, results are presented for optimized TEG legs with a void volume fraction of 0.2 that achieve compliance shear displacement of 0.0636 (from a range of 0.0504 to 0.6079). In order to achieve the necessary compliance to support the load, the power reduction is reduced by 20% relative to similarly sized void free TEG legs.


2014 ◽  
Vol 30 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Thomas Korff ◽  
Ann H. Newstead ◽  
Renate van Zandwijk ◽  
Jody L. Jensen

The purpose of this study was to examine the interactions between aging, activity levels and maximal power production during cycling. Participants were divided into younger adults (YA), older active adults (OA,) and older sedentary adults (OS). Absolute maximum power was significantly greater in YA compared with OS and OA; no differences were found between OA and OS. The age-related difference in maximum power was accompanied by greater absolute peak knee extension and knee flexion powers. Relative joint power contributions revealed both age- and activity-related differences. YA produced less relative hip extension power than older adults, regardless of activity level. The OS participants produced less relative knee flexion power than active adults, regardless of age. The results show the age-related decline in muscular power production is joint specific and that activity level can be a modifier of intersegmental coordination, which has implications for designing interventions for the aging population.


2018 ◽  
Vol 4 (1) ◽  
pp. 00073-2017 ◽  
Author(s):  
John H. Riley ◽  
Chris J. Kalberg ◽  
Alison Donald ◽  
David A. Lipson ◽  
Muhammad Shoaib ◽  
...  

This multicentre, randomised, double-blind, placebo-controlled, two-period crossover study assessed the effect of umeclidinium/vilanterol (UMEC/VI) on exercise capacity in patients with chronic obstructive pulmonary disease (COPD) using the endurance shuttle walk test (ESWT).Patients were randomised 1:1 to one of two treatment sequences: 1) UMEC/VI 62.5/25 µg followed by placebo or 2) placebo followed by UMEC/VI 62.5/25 µg. Each treatment was taken once daily for 12 weeks. The primary end-point was 3-h post-dose exercise endurance time (EET) at week 12. Secondary end-points included trough forced expiratory volume in 1 s (FEV1) and 3-h post-dose functional residual capacity (FRC), both at week 12. COPD Assessment Test (CAT) score at week 12 was also assessed.UMEC/VI treatment did not result in a statistically significant improvement in EET change from baseline at week 12 versus placebo (p=0.790). However, improvements were observed in trough FEV1 (206 mL, 95% CI 167–246), 3-h post-dose FRC (−346 mL, 95% CI −487 to −204) and CAT score (−1.07 units, 95% CI −2.09 to −0.05) versus placebo at week 12.UMEC/VI did not result in improvements in EET at week 12 versus placebo, despite improvements in measures of lung function, hyperinflation and health status.


1997 ◽  
Vol 273 (3) ◽  
pp. C1057-C1063 ◽  
Author(s):  
S. J. Swoap ◽  
V. J. Caiozzo ◽  
K. M. Baldwin

Force-velocity (FV) relationships have been used previously to calculate maximal power production and to identify an optimal velocity of shortening (V(opt)-fv) to produce such power in skeletal muscle. The cyclical nature of muscle position during locomotion for muscles such as the soleus and plantaris is such that either constant force or velocity is rarely attained. In the present study, the work loop technique, a technique developed to measure maximal attainable power output from muscles undergoing cyclic length changes, was undertaken to determine whether simulating in vivo function alters the power-velocity relationship of the soleus and plantaris and, in particular, the velocity of shortening that produces maximal power (V(opt)-wl). FV relationships were determined for both soleus (n = 4) and plantaris (n = 4) muscles in situ from adult female Sprague-Dawley rats by measuring shortening velocities during afterloaded isotonic contractions. The velocity that produced maximal power using FV relationships, V(opt)-fv, was 54.6 +/- 0.7 mm/s for the plantaris vs. 20.2 +/- 1.2 mm/s for the soleus. Then, the work loop technique was employed to measure net power from these same muscles at multiple cycling frequencies (1.5 to 4.0 Hz for the soleus; 4.0 to 8.0 Hz for the plantaris). Multiple power-velocity curves were generated (one at each cycle frequency) by varying the strain (1-8 mm). Thus, at each cycle frequency, V(opt)-wl could be identified. For both the plantaris and soleus, V(opt)-wl at each cycle frequency was not different from their respective V(opt)-fv value. Thus both fast and slow skeletal muscles have inherent optimal shortening velocities, identifiable with FV relationships, that dictate their respective maximal attainable mechanical power production using the work loop technique.


2005 ◽  
Vol 289 (4) ◽  
pp. R1144-R1154 ◽  
Author(s):  
Karen Guerrero ◽  
Bernard Wuyam ◽  
Paulette Mezin ◽  
Isabelle Vivodtzev ◽  
Marko Vendelin ◽  
...  

Mechanisms responsible for limitation of exercise capacity in lung transplant recipients (LR) and benefits gained by exercise training were studied. Mitochondrial respiration parameters, energy transfer, and cell structure were assessed in vastus lateralis biopsies using the permeabilized fiber technique with histochemical and morphometric measurements. Twelve male controls (C) and 12 LR performed exercise training over 12 wk. Before exercise training, there were strong correlations between exercise capacity (maximal O2 consumption and endurance time at 70% maximal power output) and cellular events, as assessed by percentage of type I fibers and apparent Km for exogenous ADP. Anticalcineurins were not involved in LR exercise limitation, since there were no differences in maximal mitochondrial rate of respiration before exercise training and no abnormalities in respiratory chain complexes compared with C. Training resulted in a significant increase in physiological parameters both at the cellular (apparent Km for exogenous ADP and stimulating effect of creatine) and integrated (maximal O2 consumption, power output at ventilatory threshold, maximal power output, and endurance time at 70% maximal power output) levels in LR and C. After the training period, improvements in maximal O2 consumption and in maximal mitochondrial rate of respiration were noted, as well as changes in endurance time and percentage of type I fibers. Because there were no changes in diameters and fiber types, baseline alteration of apparent Km for exogenous ADP and its improvement after training might be related to changes within the intracellular energetic units. After the training period, intracellular energetic units exhibited a higher control of mitochondrial respiration by creatine linked to a more efficient functional coupling adenine nucleotide translocase-mitochondrial creatine kinase, resulting in better exercise performances in C and LR.


2012 ◽  
Vol 106 (10) ◽  
pp. 1413-1420 ◽  
Author(s):  
Helgo Magnussen ◽  
Pierluigi Paggiaro ◽  
Hendrik Schmidt ◽  
Steven Kesten ◽  
Norbert Metzdorf ◽  
...  

2017 ◽  
Vol 50 (4) ◽  
pp. 1701235 ◽  
Author(s):  
Sara J. Abdallah ◽  
Courtney Wilkinson-Maitland ◽  
Nathalie Saad ◽  
Pei Zhi Li ◽  
Benjamin M. Smith ◽  
...  

The objective of the present study was to evaluate the effect of morphine on exertional breathlessness and exercise endurance in advanced chronic obstructive pulmonary disease (COPD).In a randomised crossover trial, we compared the acute effect of immediate-release oral morphineversusplacebo on physiological and perceptual responses during constant-load cardiopulmonary cycle exercise testing (CPET) in 20 adults with advanced COPD and chronic breathlessness syndrome.Compared with placebo, morphine reduced exertional breathlessness at isotime by 1.2±0.4 Borg units and increased exercise endurance time by 2.5±0.9 min (both p≤0.014). During exercise at isotime, morphine decreased ventilation by 1.3±0.5 L·min−1and breathing frequency by 2.0±0.9 breaths·min−1(both p≤0.041). Compared with placebo, morphine decreased exertional breathlessness at isotime by ≥1 Borg unit in 11 participants (responders) and by <1 Borg unit in nine participants (non-responders). Baseline participant characteristics, including pulmonary function and cardiorespiratory fitness, were similar between responders and non-responders. A higher percentage of respondersversusnon-responders stopped incremental CPET due to intolerable breathlessness: 82versus33% (p=0.028).Immediate-release oral morphine improved exertional breathlessness and exercise endurance in some, but not all, adults with advanced COPD. The locus of symptom-limitation on laboratory-based CPET may help to identify patients most likely to benefit from morphine.


1991 ◽  
Vol 70 (4) ◽  
pp. 1770-1774 ◽  
Author(s):  
G. G. Giesbrecht ◽  
A. Puddy ◽  
M. Ahmed ◽  
M. Younes ◽  
N. R. Anthonisen

We studied whether exercise endurance under normobaric hypoxia can be enhanced by increasing hypoxic ventilatory sensitivity with almitrine bismesylate (ALM). On both ALM and placebo (PL) days, resting subjects breathed a hypoxic gas mixture (an inspired O2 fraction of 10.4-13.2%), which lowered resting arterial O2 saturation (SaO2) to 80%. After 15 min of rest there was a 3-min warm-up period of exercise at 50 W (light) on a cycle ergometer, followed by a step increase in load to 60% of the previously determined maximum power output with room-air breathing (moderate), which was maintained until exhaustion. With PL, SaO2 decreased rapidly with the onset of exercise and continued to fall slowly during moderate exercise, averaging 71.0 +/- 1.8% (SE) at exhaustion. With ALM, saturation did not differ from PL during air breathing but significantly exceeded SaO2 with PL, by 3.4% during resting hypoxia, by 4.0% at the start of exercise, and by 5.9% at exhaustion. Ventilation was not affected by ALM during air breathing and was slightly, although not significantly, increased during hypoxic rest and exercise. ALM was associated with an increased heart rate during room air breathing but not during hypoxia. Endurance time was 20.6 +/- 1.6 min with ALM and 21.3 +/- 0.9 min with PL. During hypoxic exercise, the potential benefit of greater saturation with ALM is apparently offset by other unidentified factors.


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