Seasonal changes in wildland firefighter fitness and body composition

2020 ◽  
Vol 29 (3) ◽  
pp. 294
Author(s):  
Steven E. Gaskill ◽  
Charles L. Dumke ◽  
Charles G. Palmer ◽  
Brent C. Ruby ◽  
Joseph W. Domitrovich ◽  
...  
Keyword(s):  
Body Composition ◽  
Aerobic Fitness ◽  
Ventilatory Threshold ◽  
Wildland Fire ◽  
Fire Suppression ◽  
Metabolic Cost ◽  
Load Carriage ◽  
Fat Free Mass ◽  
Fire Season ◽  
Exercise Treadmill

Hiking with a pack is the highest-intensity task that wildland firefighters (WLFFs) perform during sustained activities related to wildland fire suppression. Firefighters perform this and other tasks together as a crew; this provides a unique model to evaluate select physical and physiological changes in members of working crews over a fire season during extended operations. The objective of this study was to evaluate changes in peak aerobic fitness (VO2peak), sustainable aerobic fitness at the ventilatory threshold (VO2vt) and body composition over a 5-month wildland fire season. WLFFs from four crews (55 males, 10 females) participated in a maximal graded exercise treadmill test and body composition evaluation pre- and post season. VO2peak values and variance did not change across the fire season (pre=3.96±0.65, post=3.96±0.69Lmin−1, not significant). VO2vt average decreased slightly while variance decreased greatly within each crew (pre=37.5±7.0, post=35.4±2.3mLkg−1 min−1, P<0.05). There was an improvement in VO2vt in initially less-fit WLFFs and a VO2vt decrease in initially more-fit WLFFs. WLFFs lost fat mass (−1.56±−1.06kg, P<0.01) and fat-free mass (−0.38±−1.24kg, P<0.05). Post-season VO2vt values were the same as the higher range of the documented metabolic cost of uphill load carriage and reveal a unique group adaptation to extended physical demands.

Resting metabolic rate is lower in women than in men

1993 ◽  
Vol 75 (6) ◽  
pp. 2514-2520 ◽  
Author(s):  
P. J. Arciero ◽  
M. I. Goran ◽  
E. T. Poehlman
Keyword(s):  
Body Composition ◽  
Metabolic Rate ◽  
Fat Mass ◽  
Aerobic Fitness ◽  
Resting Metabolic Rate ◽  
Fat Free Mass ◽  
Peak Oxygen Consumption ◽  
Activity Peak ◽  
Peak Vo2 ◽  
And Gender

This study examined gender differences in resting metabolic rate (RMR) across a broad age spectrum after controlling for differences in body composition and aerobic fitness. Three hundred twenty-eight healthy men (17–80 yr) and 194 women (18–81 yr) volunteers were characterized for RMR, body composition, physical activity, peak oxygen consumption (peak VO2), anthropometrics, and energy intake. Measured RMR was 23% higher (P < 0.01) in men (1,740 +/- 194 kcal/day) than in women (1,348 +/- 125 kcal/day). Multiple regression analysis showed that 84% of individual variation in RMR was explained by fat-free mass, fat mass, peak VO2, and gender. After controlling for differences in fat-free mass, fat mass, and peak VO2, a lower RMR (3%; P < 0.01) persisted in women (1,563 +/- 153 kcal/day) compared with men (1,613 +/- 127 kcal/day). Adjusted RMR in premenopausal (P < 0.01) and postmenopausal (P < 0.05) women was lower than in men of a similar age. Our results support a lower RMR in women than in men that is independent of differences in body composition and aerobic fitness.

Relationship between aerobic fitness level and daily energy expenditure in weight-stable humans

1992 ◽  
Vol 263 (1) ◽  
pp. E121-E128 ◽  
Author(s):  
T. A. Sharp ◽  
G. W. Reed ◽  
M. Sun ◽  
N. N. Abumrad ◽  
J. O. Hill
Keyword(s):  
Body Composition ◽  
Energy Expenditure ◽  
Aerobic Fitness ◽  
Resting Metabolic Rate ◽  
Fat Free Mass ◽  
Daily Energy Expenditure ◽  
Cross Sectional ◽  
Fitness Level ◽  
Daily Energy ◽  
The Relationship

The relationship between exercise and energy expenditure is unclear, with some suggestions that exercise leads to increased energy expenditure over and beyond the increase due to the exercise itself. In this cross-sectional study, we examined the relationships among aerobic fitness level, body composition, and total daily energy expenditure in 78 subjects. Daily energy expenditure (determined in a whole room calorimeter) was significantly correlated with both fat-free mass (FFM) and aerobic fitness (estimated from maximum aerobic capacity or VO2max). However, multiple-regression analysis demonstrated that, after accounting for FFM, VO2max did not explain a significant amount of the remaining variation in energy expenditure. In addition, the relationship between resting metabolic rate and both FFM and VO2max was evaluated using data from 214 weight-stable subjects analyzed retrospectively. The results were identical with the results obtained from the 78 subjects in that VO2max did not have effects independent of FFM on energy expenditure. We conclude that aerobic fitness does not have a direct effect on energy expenditure. However, it may have effects that are mediated through body composition, since in both populations studied here, VO2max was positively correlated with FFM and negatively correlated with adiposity.

Project Aquarius 11. Effects of Fitness, Fatness, Body Size, and Age on the Energy Expenditure, Strain, and Productivity of Men Suppressing Wildland Fires

1997 ◽  
Vol 7 (2) ◽  
pp. 181 ◽  
Author(s):  
JR Brotherhood ◽  
GM Budd ◽  
AL Hendrie ◽  
SE Jeffery ◽  
FA Beasley ◽  
...  
Keyword(s):  
Body Size ◽  
Heat Tolerance ◽  
Aerobic Fitness ◽  
Fire Suppression ◽  
Tolerance Test ◽  
Fat Free Mass ◽  
Building Performance ◽  
Laboratory Findings ◽  
Limited Application ◽  
Eucalypt Forests

Multiple-regression analyses were done to evaluate the effects of aerobic fitness (maximum oxygen uptake per kg fat-free mass), fatness (body fat content, %), body size (as reflected in fat-free mass), and age on the strain (i.e. the physiological and subjective responses) and fireline productivity of four crews of firefighters (N=21) while (1) they undertook 'line rakes', in which they attempted to suppress well-developed experimental bushfires of intensities commonly faced by hand-tool crews, and also built fireline in the same way without fire, during three summers in Australian eucalypt forests; and (2) they underwent the Shvartz heat-tolerance test, which requires 15 minutes of step-climbing at a fixed pace in a room temperature of 23°C. The results showed that the expected effects of fitness and fatness, established through laboratory studies and confirmed in the Shvartz test, were attenuated or absent during the line rakes, apparently because of self pacing and the absence of rapid climbing. In the line rakes fitter men did not work harder than the less fit but were more productive and efficient and had somewhat lower heart rates; fatter men tended to be more productive than leaner men but did not experience greater strain; bigger men (as measured by fat-free mass) were more productive than smaller men; age had no effect on strain or productivity; and associations observed during work in both the line rakes and the Shvartz test were already present before the work commenced, apparently because of emotional arousal. Responses in the Shvartz test (including the heat-tolerance score) were uncorrelated with their counterparts in the line rakes, emphasising the limited application of laboratory findings to normal fire-suppression duties. Productivity and efficiency in timed trials of firefighters' line-building performance were uncorrelated with their counterparts during the line rakes. We conclude that the adverse effects of fatness or low aerobic fitness are minimized by work practices that allow firefighters to adjust their own pace, but will become apparent whenever the pace is fixed, the terrain is steep, or some emergency calls for sustained maximal effort.

scholarly journals Preceding Fall Drought Conditions and Overwinter Precipitation Effects on Spring Wildland Fire Activity in Canada

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 24
Author(s):  
Chelene Hanes ◽  
Mike Wotton ◽  
Douglas G. Woolford ◽  
David L. Martell ◽  
Mike Flannigan
Keyword(s):  
Boreal Forests ◽  
Wildland Fire ◽  
Fire Suppression ◽  
Fire Season ◽  
Fire Weather Index ◽  
Area Burned ◽  
Fire Activity ◽  
Drought Conditions ◽  
Carry Over ◽  
The Impact

Spring fire activity has increased in parts of Canada, particularly in the west, prompting fire managers to seek indicators of potential activity before the fire season starts. The overwintering adjustment of the Canadian Fire Weather Index System’s Drought Code (DC) is a method to adjust and carry-over the previous season’s drought conditions into the spring and potentially point to what lies ahead. The occurrence of spring fires is most strongly influenced by moisture in fine fuels. We used a zero-inflated Poisson regression model to examine the impact of the previous end of season Drought Code (DCf) and overwinter precipitation (Pow) while accounting for the day-to-day variation in fine fuel moisture that drives ignition potential. Impacts of DCf and Pow on area burned and fire suppression effectiveness were also explored using linear and logistic regression frameworks. Eight fire management regions across the boreal forests were analyzed using data from 1979 to 2018. For the majority of regions, drier fall conditions resulted in more human-caused spring fires, but not in greater area burned or reduced suppression effectiveness. The influence of Pow was much more variable pointing to the conclusion that Pow alone is not a good indicator of spring drought conditions.

scholarly journals Effects of Time-Restricted Feeding on Supramaximal Exercise Performance and Body Composition: A Randomized and Counterbalanced Crossover Study in Healthy Men

2021 ◽  
Vol 18 (14) ◽  
pp. 7227
Author(s):  
Joana M. Correia ◽  
Inês Santos ◽  
Pedro Pezarat-Correia ◽  
Cláudia Minderico ◽  
Brad J. Schoenfeld ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Mass ◽  
Exercise Performance ◽  
Fat Free Mass ◽  
Restricted Feeding ◽  
Supramaximal Exercise ◽  
Mean Power ◽  
Post Intervention ◽  
Dietary Record

Using a crossover design, we explored the effects of both short- and long-term time-restricted feeding (TRF) vs. regular diet on Wingate (WnT) performance and body composition in well-trained young men. Twelve healthy male physical education students were included (age: 22.4 ± 2.8 years, height: 174.0 ± 7.1 cm, body mass: 73.6 ± 9.5 kg, body mass index: 24.2 ± 2.0 kg/m2). The order of dieting was randomized and counterbalanced, and all participants served as their own controls. TRF was limited to an 8-h eating window and non-TRF involved a customary meal pattern. Participants performed WnT tests and body composition scans at baseline, post-one and post-four weeks of the assigned diet. Before testing, participants were asked to fill out a dietary record over four consecutive days and were instructed to continue their habitual training throughout the study. Energy intake and macronutrient distribution were similar at baseline in both conditions. WnT mean power and total work output increased post-four weeks of TRF. Both conditions were similarly effective in increasing fat-free mass after four weeks of intervention. However, there was no correlation between change in fat-free mass and WnT mean power after TRF. TRF did not elicit any changes in WnT performance or body composition one week post-intervention. Thus, long-term TRF can be used in combination with regular training to improve supramaximal exercise performance in well-trained men.

scholarly journals Low serum TSH levels are associated with low values of fat-free mass and body cell mass in the elderly

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Till Ittermann ◽  
Marcello R. P. Markus ◽  
Martin Bahls ◽  
Stephan B. Felix ◽  
Antje Steveling ◽  
...  
Keyword(s):  
Body Composition ◽  
Waist Circumference ◽  
Cell Mass ◽  
The Elderly ◽  
Fat Free Mass ◽  
Body Cell Mass ◽  
Body Cell ◽  
Independent Population ◽  
Serum Tsh ◽  
Tsh Levels

AbstractPrevious studies on the association between thyroid function and body composition are conflicting and showed strong differences across age groups. Our aim was to clarify age-specific associations of serum thyroid-stimulating hormone (TSH) levels with markers of body composition including body mass index (BMI), waist circumference, fat mass (FM), fat-free mass (FFM) and body cell mass (BCM). We used data from two independent population-based cohorts within the framework of the Study of Health in Pomerania. The study population included 5656 individuals aged 20 to 90 years. Markers of body composition were measured by bioelectrical impedance analysis. Serum TSH levels were significantly positively associated with BMI (β = 0.16; 95% confidence interval [CI]: 0.06 to 0.27), waist circumference (β = 0.35; 95% CI: 0.08 to 0.62) and FM (β = 0.32; 95% CI: 0.12 to 0.52), but not with FFM and BCM. Interaction analysis revealed positive associations of serum TSH levels with BMI, waist circumference, FM, FFM and BCM in individuals older than 60 years, while no such associations were observed in younger individuals. We demonstrated that lower serum TSH levels were accompanied with lower values of BMI, waist circumference, FM, FFM, and BCM in the elderly, while no such associations were observed in younger individuals.

scholarly journals Body composition changes in physically active individuals consuming ketogenic diets: a systematic review

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Julie L. Coleman ◽  
Christopher T. Carrigan ◽  
Lee M. Margolis
Keyword(s):  
Systematic Review ◽  
Body Composition ◽  
Body Mass ◽  
Risk Of Bias ◽  
Fat Free Mass ◽  
Cochrane Library ◽  
Ideal Strength ◽  
Physically Active ◽  
Ketogenic Diets ◽  
Study Intervention

Abstract Background To achieve ideal strength/power to mass ratio, athletes may attempt to lower body mass through reductions in fat mass (FM), while maintaining or increasing fat-free mass (FFM) by manipulating their training regimens and diets. Emerging evidence suggests that consumption of high-fat, ketogenic diets (KD) may be advantageous for reducing body mass and FM, while retaining FFM. Methods A systematic review of the literature was conducted using PubMed and Cochrane Library databases to compare the effects of KD versus control diets (CON) on body mass and composition in physically active populations. Randomized and non-randomized studies were included if participants were healthy (free of chronic disease), physically active men or women age ≥ 18 years consuming KD (< 50 g carbohydrate/d or serum or whole blood β-hydroxybutyrate (βhb) > 0.5 mmol/L) for ≥14 days. Results Thirteen studies (9 parallel and 4 crossover/longitudinal) that met the inclusion criteria were identified. Aggregated results from the 13 identified studies show body mass decreased 2.7 kg in KD and increased 0.3 kg in CON. FM decreased by 2.3 kg in KD and 0.3 kg in CON. FFM decreased by 0.3 kg in KD and increased 0.7 kg in CON. Estimated energy balance based on changes in body composition was − 339 kcal/d in KD and 5 kcal/d in CON. Risk of bias identified some concern of bias primarily due to studies which allowed participants to self-select diet intervention groups, as well as inability to blind participants to the study intervention, and/or longitudinal study design. Conclusion KD can promote mobilization of fat stores to reduce FM while retaining FFM. However, there is variance in results of FFM across studies and some risk-of-bias in the current literature that is discussed in this systematic review.

Body Composition Modifications Due to the “Search, Rescue and Survival Training” in Male Military Firefighter Cadets

2021 ◽  
Author(s):  
Thiago Ramos de Barros ◽  
Verônica Pinto Salerno ◽  
Thalita Ponce ◽  
Míriam Raquel Meira Mainenti
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Repeated Measures ◽  
Food Restriction ◽  
Physical Exertion ◽  
High Energy ◽  
The Body ◽  
Fat Free Mass ◽  
Sleep Restriction ◽  
Fat Percentage

ABSTRACT Introduction To train and prepare cadets for a career as firefighters in Rio de Janeiro, the second-year students of the Officers Training Course are submitted to a Search, Rescue, and Survival Training (SRST) course, which is characterized by long periods of high physical exertion and sleep restriction during a 9-day instruction module, and food restriction during a 7-day survival module. The present study investigated changes in the body composition of 39 male cadets submitted to SRST during training and 4 weeks of recovery with no restrictions in food consumption. Materials and Methods Each cadet was evaluated by anthropometric measurements at six time points: pre-SRST; after the first module; after the second module; and after 1, 2, and 4 weeks of recovery. Measurements included body girths and skinfolds, to estimate trunk (chest and waist) and limbs (arm and thigh) dimensions, as well as body composition. Repeated measures ANOVA and Friedman test were applied (depending on each data distribution). Results Statistically significant decreases in body weight (76.2; 69.8-87.2 to 63.9; 58.9-73.5 kg) and fat free mass (FFM, 69.2; 63.7-77.2 to 60.1; 56.2-68.0 kg) were observed following the second module of SRST. Following a single week of recovery, the FFM returned to pre-SRST values. Body weight returned to pre-training levels in 2 weeks. Body fat percentage and mass also significantly decreased during SRST (9.0; 7.7-12.3 to 6.5; 5.1-9.3% and 6.9; 5.6-10.0 to 6.9; 5.6-10.0 kg, respectively), which showed a slower and more gradual recovery that reached pre-SRST values after 4 weeks. The girths of arm, thigh, chest and waist significantly decreased due to SRST. The girths of the limbs (arm and thigh) returned to pre-training values after one month of recovery, while the girths of the trunk (chest and waist) did not return to pre-SRST values during the study period. Conclusions The findings suggest that men who experience periods of high energy demands and sleep restriction followed by a period of food restriction will endure unavoidable physical consequences that can be mostly reversed by a 1-month recovery.

What Physical Fitness Component Is Most Closely Associated With Adolescents' Blood Pressure?

2017 ◽  
Vol 124 (6) ◽  
pp. 1107-1120 ◽  
Author(s):  
Heloyse E. G. Nunes ◽  
Carlos A. S. Alves ◽  
Eliane C. A. Gonçalves ◽  
Diego A. S. Silva
Keyword(s):  
Blood Pressure ◽  
Body Composition ◽  
Muscle Strength ◽  
Physical Fitness ◽  
Systolic Blood Pressure ◽  
Diastolic Blood Pressure ◽  
Aerobic Fitness ◽  
Pressure Control ◽  
Cross Sectional ◽  
Digital Pressure

This study aimed to determine which of four selected physical fitness variables, would be most associated with blood pressure changes (systolic and diastolic) in a large sample of adolescents. This was a descriptive and cross-sectional, epidemiological study of 1,117 adolescents aged 14–19 years from southern Brazil. Systolic and diastolic blood pressure were measured by a digital pressure device, and the selected physical fitness variables were body composition (body mass index), flexibility (sit-and-reach test), muscle strength/resistance (manual dynamometer), and aerobic fitness (Modified Canadian Aerobic Fitness Test). Simple and multiple linear regression analyses revealed that aerobic fitness and muscle strength/resistance best explained variations in systolic blood pressure for boys (17.3% and 7.4% of variance) and girls (7.4% of variance). Aerobic fitness, body composition, and muscle strength/resistance are all important indicators of blood pressure control, but aerobic fitness was a stronger predictor of systolic blood pressure in boys and of diastolic blood pressure in both sexes.

scholarly journals Body composition in childhood: effects of normal growth and disease

2003 ◽  
Vol 62 (2) ◽  
pp. 521-528 ◽  
Author(s):  
J. C. K. Wells
Keyword(s):  
Body Composition ◽  
Childhood Obesity ◽  
Fat Mass ◽  
Lean Mass ◽  
Normal Weight ◽  
Fat Free Mass ◽  
General Interest ◽  
Childhood And Adolescence ◽  
Adult Disease ◽  
Increased Risk

Body composition in children is of increasing interest within the contexts of childhood obesity, clinical management of patients and nutritional programming as a pathway to adult disease. Energy imbalance appears to be common in many disease states; however, body composition is not routinely measured in patients. Traditionally, clinical interest has focused on growth or nutritional status, whereas more recent studies have quantified fat mass and lean mass. The human body changes in proportions and chemical composition during childhood and adolescence. Most of the weight gain comprises lean mass rather than fat. In general, interest has focused on percentage fat, and less attention has been paid to the way in which lean mass varies within and between individuals. In the general population secular trends in BMI have been widely reported, indicating increasing levels of childhood obesity, which have been linked to reduced physical activity. However, lower activity levels may potentially lead not only to increased fatness, but also to reduced lean mass. This issue merits further investigation. Diseases have multiple effects on body composition and may influence fat-free mass and/or fat mass. In some diseases both components change in the same direction, whereas in other diseases, the changes are contradictory and may be concealed by relatively normal weight. Improved techniques are required for clinical evaluations. Both higher fatness and reduced lean mass may represent pathways to an increased risk of adult disease.

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