Optimum gradient of mountain paths

1995 ◽  
Vol 79 (5) ◽  
pp. 1698-1703 ◽  
Author(s):  
A. E. Minetti
Keyword(s):  
Energy Expenditure ◽  
High Altitude ◽  
Body Mass ◽  
Metabolic Cost ◽  
Vertical Displacement ◽  
Transmission Efficiency ◽  
Metabolic Power ◽  
Gait Biomechanics ◽  
Overall Efficiency ◽  
Downhill Walking

By combining the experiment results of R. Margaria (Atti Accad. Naz. Lincei Memorie 7: 299–368, 1938), regarding the metabolic cost of gradient locomotion, together with recent insights on gait biomechanics, a prediction about the most economical gradient of mountain paths (approximately 25%) is obtained and interpreted. The pendulum-like mechanism of walking produces a waste of mechanical work against gravity within the gradient range of up to 15% (the overall efficiency is dominated by the low transmission efficiency), whereas for steeper values only the muscular efficiency is responsible for the (slight) metabolic change (per meter of vertical displacement) with respect to gradient. The speeds at the optimum gradient turned out to be approximately 0.65 m/s (+0.16 m/s vertical) and 1.50 m/s (-0.36 m/s vertical), for uphill and downhill walking, respectively, and the ascensional energy expenditure was 0.4 and 2.0 ml O2.kg body mass-1.vertical m-1 climbed or descended. When the metabolic power becomes a burden, as in high-altitude mountaineering, the optimum gradient should be reduced. A sample of real mountain path gradients, experimentally measured, mimics the obtained predictions.

scholarly journals BASAN index (Body mass index, Age, Sex, Arterial hypertension and Neck circumference) predicts severe apnoea in adults living at high altitude

BMJ Open ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. e044228
Author(s):  
Henry Oliveros ◽  
Rafael Lobelo ◽  
Luis Fernando Giraldo-Cadavid ◽  
Alirio Bastidas ◽  
Constanza Ballesteros ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Arterial Hypertension ◽  
High Altitude ◽  
Body Mass ◽  
Sleep Apnoea ◽  
Neck Circumference ◽  
Binary Logistic Regression Model ◽  
Cross Sectional ◽  
Derivation Cohort ◽  
Obstructive Sleep

ObjectivesObstructive sleep apnoea (OSA)/hypopnoea syndrome is associated with serious and major multiorgan morbidities, particularly in its most severe forms. However, no severe OSA screening instruments are available for high altitude residents that enable adequate identification and clinical prioritisation of such patients. We aimed at developing a severe OSA prediction tool based on the clinical characteristics and anthropometric measurements of a clinical referral cohort living at 2640 m.a.s.l.DesignCohort-nested cross-sectional study.SettingSleep laboratory for standard polysomnography (PSG) in Colombia.ParticipantsA predictive model was generated from 8718 participants referred to the PSG laboratory. Results were subsequently validated in a second cohort of 1898 participants.Primary outcomeTo identify clinical and anthropometric variables associated with severe OSA (>30 events/hour) and to include them in a binary logistic regression model.ResultsThe significant variables that were retained with the presence of severe OSA included Body mass index (BMI), Age, Sex, Arterial hypertension and Neck circumference (BASAN). The area under the receiver operating characteristic curvefor the BASAN index was 0.69 (95% CI: 0.68 to 0.70) in the derivation cohort and 0.67 (95% CI: 0.65 to 0.69) in the validation cohort, whereby a BASAN index ≥2 had a sensitivity of 95% and a specificity of 17% to detect severe OSA.ConclusionAn objectively based approach to screen for the presence of severe OSA, the BASAN index, exhibits favourable sensitivity characteristics that should enable its operational use as a screening tool in a Hispanic population with a clinical suspicion of OSA and living at high altitude.

scholarly journals The energy allocation trade-offs underlying life history traits in hypometabolic strepsirhines and other primates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bruno Simmen ◽  
Luca Morino ◽  
Stéphane Blanc ◽  
Cécile Garcia
Keyword(s):  
Life History ◽  
Energy Expenditure ◽  
Body Mass ◽  
Life History Traits ◽  
Brain Size ◽  
Energy Allocation ◽  
Interbirth Interval ◽  
Energy Investment ◽  
Litter Mass ◽  
Trade Offs

AbstractLife history, brain size and energy expenditure scale with body mass in mammals but there is little conclusive evidence for a correlated evolution between life history and energy expenditure (either basal/resting or daily) independent of body mass. We addressed this question by examining the relationship between primate free-living daily energy expenditure (DEE) measured by doubly labeled water method (n = 18 species), life history variables (maximum lifespan, gestation and lactation duration, interbirth interval, litter mass, age at first reproduction), resting metabolic rate (RMR) and brain size. We also analyzed whether the hypometabolic primates of Madagascar (lemurs) make distinct energy allocation tradeoffs compared to other primates (monkeys and apes) with different life history traits and ecological constraints. None of the life-history traits correlated with DEE after controlling for body mass and phylogeny. In contrast, a regression model showed that DEE increased with increasing RMR and decreasing reproductive output (i.e., litter mass/interbirth interval) independent of body mass. Despite their low RMR and smaller brains, lemurs had an average DEE remarkably similar to that of haplorhines. The data suggest that lemurs have evolved energy strategies that maximize energy investment to survive in the unusually harsh and unpredictable environments of Madagascar at the expense of reproduction.

Energy expenditure during load carriage at high altitude

1981 ◽  
Vol 51 (1) ◽  
pp. 14-18 ◽  
Author(s):  
A. Cymerman ◽  
K. B. Pandolf ◽  
A. J. Young ◽  
J. T. Maher
Keyword(s):  
Energy Expenditure ◽  
High Altitude ◽  
Sea Level ◽  
Prediction Equation ◽  
Cycle Ergometer ◽  
Load Carriage ◽  
Metabolic Rates ◽  
Specific Exercise ◽  
Upper Limit ◽  
Predicted Values

To determine the applicability of a prediction equation for energy expenditure during load carriage at high altitude that was previously validated at sea level, oxygen uptake (Vo2) was determined in five young men at 4,300 m while they walked with backpack loads of 0, 15, and 30 kg at treadmill grades of 0,8, and 16% at 1.12 m.s-1 for 10 min. Mean +/- SE maximal Vo2, determined on the cycle ergometer, was 42.2 +/- 2.3 at sea level and 35.6 +/- 1.7 ml.kg-1 .min-1 at altitude. There were no significant differences in daily Vo2 at any specific exercise intensity on days 1, 5, and 9 of exposure, nor were there any differences in endurance times at the two most difficult exercise intensities. Endurance times for 15- and 30-kg loads at 16% grade were 7.3 and 4.2 min, respectively. Measured energy expenditure was compared with that predicted by the formula of Pandolf et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 43: 577–581, 1977) and found to be significantly different. The differences could be attributed to measurements at metabolic rates exceeding 730 W or 2.1 1.min-1 Vo2. These data indicate that the prediction equation can be used at altitude for exercise intensities not exceeding this upper limit. The observed deviations from predicted values at the high exercise intensities could possibly be attributed to the occurrence of appreciable oxygen deficits and the inability to achieve steady-state conditions.

scholarly journals Influence of body composition on physical activity validation studies using doubly labeled water

2004 ◽  
Vol 96 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
Louise C. Mâsse ◽  
Janet E. Fulton ◽  
Kathleen L. Watson ◽  
Matthew T. Mahar ◽  
Michael C. Meyers ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Composition ◽  
Energy Expenditure ◽  
Body Mass ◽  
Resting Metabolic Rate ◽  
Fat Free Mass ◽  
Doubly Labeled Water ◽  
Comparison Analysis ◽  
Methods Comparison ◽  
Statistical Procedures

This study investigated the influence of two approaches (mathematical transformation and statistical procedures), used to account for body composition [body mass or fat-free mass (FFM)], on associations between two measures of physical activity and energy expenditure determined by doubly labeled water (DLW). Complete data for these analyses were available for 136 African American (44.1%) and Hispanic (55.9%) women (mean age 50 ± 7.3 yr). Total energy expenditure (TEE) by DLW was measured over 14 days. Physical activity energy expenditure (PAEE) was computed as 0.90 × TEE - resting metabolic rate. During week 2, participants wore an accelerometer for 7 consecutive days and completed a 7-day diary. Pearson's product-moment correlations and three statistical procedures (multiple regressions, partial correlations, and allometric scaling) were used to assess the effect of body composition on associations. The methods-comparison analysis was used to study the effect of body composition on agreement. The statistical procedures demonstrated that associations improved when body composition was included in the model. The accelerometer explained a small but meaningful portion of the variance in TEE and PAEE after body mass was accounted for. The methods-comparison analysis confirmed that agreement with DLW was affected by the transformation. Agreement between the diary (transformed with body mass) and TEE reflected the association that exists between body mass and TEE. These results suggest that the accelerometer and diary accounted for a small portion of TEE and PAEE. Most of the variance in DLW-measured energy expenditure was explained by body mass or FFM.

Serum leptin levels and energy expenditure in normal weight women

1998 ◽  
Vol 76 (2) ◽  
pp. 237-241 ◽  
Author(s):  
L J Martin ◽  
PJH Jones ◽  
R V Considine ◽  
W Su ◽  
N F Boyd ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Food Intake ◽  
Energy Expenditure ◽  
Body Mass ◽  
Body Fat ◽  
Positive Association ◽  
Normal Weight ◽  
Serum Leptin ◽  
Percentage Body Fat ◽  
Healthy Humans

To investigate whether circulating leptin levels are associated with energy expenditure in healthy humans, doubly labeled water energy measurements and food intake assessment were carried out in 27 women (mean age, 48.6 years; weight, 61.9 kg; body mass index, 23.2). Energy expenditure was determined over 13 days. Food intake was measured by 7-day food records. Leptin was measured by radioimmunoassay. Leptin level was strongly associated with percentage body fat (r = 0.59; p < 0.001), fat mass (r = 0.60; p < 0.001), and body mass index (r = 0.41; p = 0.03), but no correlation was observed with energy expenditure (r = 0.02; p = 0.93). After controlling for percentage body fat, a positive association of leptin level with energy expenditure of marginal significance (p = 0.06) was observed. There were no significant univariate associations of age, physical activity, lean body mass, height, or dietary variables with leptin level. When controlling for body fat, a significant positive correlation was observed for percent energy from carbohydrate and negative correlations with dietary fat and alcohol intake. These findings confirm previous associations between leptin and body fat content and suggest a relationship between serum leptin and energy expenditure level in healthy humans.Key words: leptin, energy expenditure, body composition, diet.

scholarly journals Disentangling the energetic costs of step time asymmetry and step length asymmetry in human walking

2021 ◽  
Author(s):  
Jan Stenum ◽  
Julia T. Choi
Keyword(s):  
Energy Cost ◽  
Metabolic Cost ◽  
Step Length ◽  
Human Walking ◽  
Metabolic Power ◽  
Healthy Human ◽  
Time Asymmetry ◽  
Double Support ◽  
Post Stroke ◽  
The Cost

The metabolic cost of walking in healthy individuals increases with spatiotemporal gait asymmetries. Pathological gait, such as post-stroke, often has asymmetry in step lengths and step times which may contribute to an increased energy cost. But paradoxically, enforcing step length symmetry does not reduce metabolic cost of post-stroke walking. The isolated and interacting costs of asymmetry in step times and step lengths remain unclear, because previous studies did not simultaneously enforce spatial and temporal gait asymmetries. Here, we delineate isolated costs of asymmetry in step times and step lengths in healthy human walking. We first show that the cost of step length asymmetry is predicted by the cost of taking two non-preferred step lengths (one short and one long), but that step time asymmetry adds an extra cost beyond the cost of non-preferred step times. The metabolic power of step time asymmetry is about 2.5 times greater than the cost of step length asymmetry. Furthermore, the costs are not additive when walking with asymmetric step times and step lengths: metabolic power of concurrent asymmetry in step lengths and step times is driven by the cost of step time asymmetry alone. The metabolic power of asymmetry is explained by positive mechanical power produced during single support phases to compensate for a net loss of center of mass power incurred during double support phases. These data may explain why metabolic cost remains invariant to step length asymmetry in post-stroke walking and suggests how effects of asymmetry on energy cost can be attenuated.

An Evaluation of the Kenz Calorie Counter during Progressive Treadmill Exercise in Adults and Children

1996 ◽  
Vol 8 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Nicholas J. Walters ◽  
David A. Brodie
Keyword(s):  
Linear Regression ◽  
Energy Expenditure ◽  
Body Mass ◽  
Correction Factor ◽  
Treadmill Exercise ◽  
Gas Analysis ◽  
Age Group ◽  
Measured Energy ◽  
Adults And Children ◽  
On Line

The purpose of this study was to assess the validity of data derived from the Kenz calorie counter during progressive, incremental treadmill exercise. Direct comparisons were made with calories calculated from on-line gas analysis. The subjects were 18 adults, 18 postadolescent children, and 24 preadolescent children. Linear regression (r2 > .95) showed a progressive deviation away from a 1:1 relationship between Kenz data and V̇O2 data with increasing age of subject which remained when standardized to kcal · kg−1 body mass or kcal · m−2 · hour−1. The Kenz calorie counter, after applying an age group correction factor, can thus be used as a suitable analog for measured energy expenditure.

Chronic Intermittent High Altitude Exposure, Occupation, and Body Mass Index in Workers of Mining Industry

2014 ◽  
Vol 15 (3) ◽  
pp. 412-417 ◽  
Author(s):  
Marina K. Esenamanova ◽  
Firuza A. Kochkorova ◽  
Tatyana A. Tsivinskaya ◽  
Denis Vinnikov ◽  
Kairgeldy Aikimbaev
Keyword(s):  
Body Mass Index ◽  
High Altitude ◽  
Body Mass ◽  
Mining Industry ◽  
Altitude Exposure

scholarly journals Energy expenditure of trans-tibial amputees during ambulation at self-selected pace

1994 ◽  
Vol 18 (2) ◽  
pp. 84-91 ◽  
Author(s):  
R. S. Gailey ◽  
M. A. Wenger ◽  
M. Raya ◽  
N. Kirk ◽  
K. Erbs ◽  
...  
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Energy Expenditure ◽  
Energy Cost ◽  
Metabolic Cost ◽  
The Self ◽  
Healthy Male ◽  
Subject Pool

The purpose of this investigation was two-fold: 1) to compare the metabolic cost (VO2), heart rate (HR), and self-selected speed of ambulation of trans-tibial amputees (TTAs) with those of non-amputee subjects; and 2) to determine whether a correlation exists between either stump length or prosthesis mass and the energy cost of ambulation at the self-selected ambulation pace of TTAs. Subjects were thirty-nine healthy male non-vascular TTAs between the ages of 22 and 75 years (mean ± sd = 47 ± 16). All had regularly used their prosthesis for longer than six months and were independent of assistive ambulation devices. Twenty-one healthy non-amputee males aged 27–47 years (31 ± 6) served as controls. Subjects ambulated at a self-selected pace over an indoor course, with steady-state VO2, HR, and ambulation speed averaged across minutes seven, eight and nine of walking. Results showed that HR and VO2 for TTAs were 16% greater, and the ambulation pace 11% slower than the non-amputee controls. Significant correlations were not observed between stump length or prosthesis mass and the energy cost of ambulation. However, when the TTA subject pool was stratified on the basis of long and short stump length, the former sustained significantly lower steady-state VO2 and HR than the latter while walking at comparable pace. These data indicate that stump length may influence the metabolic cost of ambulation in TTAs.

THE ENERGETIC COSTS OF CALLING IN THE BUSHCRICKET REQUENA VERTICALIS (ORTHOPTERA: TETTIGONIIDAE: LISTROSCELIDINAE)

1993 ◽  
Vol 178 (1) ◽  
pp. 21-37 ◽  
Author(s):  
W. J. Bailey ◽  
P. C. Withers ◽  
M. Endersby ◽  
K. Gaull
Keyword(s):  
Body Mass ◽  
Sound Pressure ◽  
Metabolic Cost ◽  
Acoustic Power ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Metabolic Efficiency ◽  
Metabolic Costs ◽  
Sound Pressure Levels ◽  
The Relationship

1. The metabolic costs of calling for male Requena verticalis Walker (Tettigoniidae: Listroscelidinae) were measured by direct recordings of oxygen consumption. The acoustic power output was measured by sound pressure levels around the calling bushcricket. 2. The average metabolic cost of calling was 0.143 ml g-1 h-1 but depended on calling rate. The net metabolic cost of calling per unit call, the syllable, was calculated to be 4.34×10-6+/−8.3×10-7 ml O2 syllable-1 g-1 body mass (s.e.) from the slope of the relationship between total V(dot)O2 and rate of syllable production. The resting V(dot)O2, calculated as the intercept of the relationship, was 0.248 ml O2 g-1 body mass h-1. 3. The energetic cost of calling for R. verticalis (average mass 0.37 g) was estimated at 31.85×10-6 J syllable-1. 4. Sound pressure levels were measured around calling insects. The surface area of a sphere of uniform sound pressure level [83 dB SPL root mean square (RMS) acoustic power] obtained by these measurements was used to calculate acoustic power. This was 0.20 mW. 5. The metabolic efficiency of calling, based on total metabolic energy utilisation, was 6.4 %. However, we propose that the mechanical efficiency for acoustic transmission is closer to 57 %, since only about 10 % of muscle metabolic energy is apparently available for sound production. 6. R. verticalis emits chirps formed of several syllables within which are discrete sound pulses. Wing stroke rates, when the insect is calling at its maximal rate, were approximately 583 min-1. This is slow compared to the rates observed in conehead tettigoniids, the only other group of bushcrickets where metabolic costs have been measured. The thoracic temperatures of males that had been calling for 5 min were not significantly different from those of non-calling males. 7. For R. verticalis, calling with relatively slow syllable rates may reduce the total cost of calling, and this may be a compensatory mechanism for their other high energetic cost of mating (a large spermatophylax).

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