Seasonal Variation In Body Composition Research Articles

Seasonal variation in body composition in an Afrotropical passerine bird: increases in pectoral muscle mass are, unexpectedly, associated with lower thermogenic capacity.

Phenotypic flexibility in avian metabolic rates and body composition have been well-studied in high-latitude species, which typically increase basal metabolic rate (BMR) and summit metabolism (Msum) when acclimatized to winter conditions. Patterns of seasonal metabolic acclimatization are more variable in lower-latitude birds that experience milder winters, with fewer studies investigating adjustments in avian organ and muscle masses in the context of metabolic flexibility in these regions. We quantified seasonal variation (summer vs winter) in the masses of organs and muscles frequently associated with changes in BMR (gizzard, intestines and liver) and Msum (heart and pectoral muscles), in white-browed sparrow-weavers (Plocepasser mahali). We also measured pectoral muscle thickness using a portable ultrasound system to determine whether we could non-lethally estimate muscle size. A concurrent study measured seasonal changes in BMR and Msum in the same population of sparrow-weavers, but different individuals. There was no seasonal variation in the dry masses of the gizzard, intestines or liver of sparrow-weavers, and during the same period, BMR did not vary seasonally. We found significantly higher heart (~ 18% higher) and pectoral muscle (~ 9% higher) dry mass during winter, although ultrasound measurements did not detect seasonal changes in pectoral muscle size. Despite winter increases in pectoral muscle mass, Msum was ~ 26% lower in winter compared to summer. To the best of our knowledge, this is the first study to report an increase in avian pectoral muscle mass but a concomitant decrease in thermogenic capacity.

Fat content of striped mice decreases during the breeding season but not during the food-restricted dry season.

Individuals that are capable of accumulating appropriate fat stores are assumed to have selective advantages when food becomes scarce. Similarly to species from temperate zones, some species inhabiting arid areas accumulate fat stores prior to periods of food limitation. Yet, we have little knowledge concerning seasonal variation in body composition and the relationship between fat store size and disappearance risk in species from arid habitats. Using the water dilution method, we examined the body composition of African striped mice (Rhabdomys pumilio) living in a seasonal habitat with a long food-restricted dry season. We tested for seasonal changes in body composition (N=159 measurements of 113 individuals) and whether dry season survival was related to fat mass (N=66 individuals). Fat stores were similar in size at the onset and the end of the dry season, but surprisingly smaller at the onset of the moist breeding season. Fat stores showed a negative relationship with food availability. Individual variation in fat stores was not associated with disappearance risk, but there was a positive association of disappearance risk with body mass. Increased disappearance risk of heavy individuals suggests elevated dispersal rates in competitive individuals. This study suggests that non-breeding philopatric striped mice do not accumulate large fat stores prior to the food-limited dry season but that they might mobilize fat stores at the onset of the breeding season to satisfy the energetic demands of reproduction and/or to decrease costs associated with larger fat stores, such as increased predation risk.

Seasonal variations in body composition, maximal oxygen uptake, and gas exchange threshold in cross-country skiers.

IntroductionIn order to ensure that athletes achieve their highest performance levels during competitive seasons, monitoring their long-term performance data is crucial for understanding the impact of ongoing training programs and evaluating training strategies. The present study was thus designed to investigate the variations in body composition, maximal oxygen uptake (VO2max), and gas exchange threshold values of cross-country skiers across training phases throughout a season.Materials and methodsIn total, 15 athletes who participate in international cross-country ski competitions voluntarily took part in this study. The athletes underwent incremental treadmill running tests at 3 different time points over a period of 1 year. The first measurements were obtained in July, during the first preparation period; the second measurements were obtained in October, during the second preparation period; and the third measurements were obtained in February, during the competition period. Body weight, body mass index (BMI), body fat (%), as well as VO2max values and gas exchange threshold, measured using V-slope method during the incremental running tests, were assessed at all 3 time points. The collected data were analyzed using SPSS 20 package software. Significant differences between the measurements were assessed using Friedman’s twoway variance analysis with a post hoc option.ResultsThe athletes’ body weights and BMI measurements at the third point were significantly lower compared with the results of the second measurement (p<0.001). Moreover, the incremental running test time was significantly higher at the third measurement, compared with both the first (p<0.05) and the second (p<0.01) measurements. Similarly, the running speed during the test was significantly higher at the third measurement time point compared with the first measurement time point (p<0.05). Body fat (%), time to reach the gas exchange threshold, running speed at the gas exchange threshold, VO2max, amount of oxygen consumed at gas exchange threshold level (VO2GET), maximal heart rate (HRmax), and heart rate at gas exchange threshold level (HRGET) values did not significantly differ between the measurement time points (p>0.05).ConclusionVO2max and gas exchange threshold values recorded during the third measurements, the timing of which coincided with the competitive season of the cross-country skiers, did not significantly change, but their incremental running test time and running speed significantly increased while their body weight and BMI significantly decreased. These results indicate that the cross-country skiers developed a tolerance for high-intensity exercise and reached their highest level of athletic performance during the competitive season.

Seasonal Variation in Body Composition in Boleophthalmus pectinirostris Collected from Gangjin, Jeonnam, Korea

Seasonal Variation in Body Composition in Boleophthalmus pectinirostris Collected from Gangjin, Jeonnam, Korea

Longitudinal Changes and Seasonal Variation in Body Composition in Professional Australian Football Players.

To compare development and variations in body composition of early-, mid-, and late-career professional Australian Football (AF) players over 3 successive seasons. Regional and total-body composition (body mass [BM], fat mass [FM], fat-free soft-tissue mass [FFSTM], and bone mineral content [BMC]) were assessed 4 times, at the same time of each season-start preseason (SP), end preseason (EP), midseason (MS), and end season (ES)-from 22 professional AF players using pencil-beam dual-energy X-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-d food diaries. Players were classified according to their age at the beginning of the observational period as either early- (<21 y, n = 8), mid- (21 to 25 y, n = 9), or late- (>25 y, n = 5) career athletes. Early-career players had lower FFSTM, BMC, and BM than mid- and late-career throughout. FM and %FM had greatest variability, particularly in the early-career players. FM reduced and FFSTM increased from SP to EP, while FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, while FM and FFSTM increased during the off-season. Early-career players may benefit from greater emphasis on specific nutrition and resistance-training strategies aimed at increasing FFSTM, while all players should balance training and diet toward the end of season to minimize increases in FM.

Phenotypic flexibility in migrating bats: seasonal variation in body composition, organ sizes and fatty acid profiles

Many species of bats migrate long distances, but the physiological challenges of migration are poorly understood. We tested the hypothesis that migration is physiologically demanding for bats by examining migration-related phenotypic flexibility. Both bats and birds are endothermic, flying vertebrates; therefore, we predicted that migration would result in similar physiological trade-offs. We compared hoary bats (Lasiurus cinereus) during spring migration and summer non-migratory periods, comparing our results with previous observations of birds. Migrating bats had reduced digestive organs, enlarged exercise organs, and fat stores had higher proportions of polyunsaturated fatty acids (PUFAs). These results are consistent with previous studies of migrating birds; however, we also found sex differences not typically associated with bird migration. Migrating female hoary bats increased the relative size of fat stores by reducing lean body components, while males maintained the same relative amount of fat in both seasons. The ratio of n-6 to n-3 PUFA in flight muscle membrane increased in migrating males and decreased in migrating females, consistent with males using torpor more frequently than females during spring migration. Enlarged exercise organs, reduced digestive organs and changes in adipose tissue composition reflect the elevated energetic demands of migration. Sex-specific patterns of fat storage and muscle membrane composition likely reflect challenges faced by females that migrate while pregnant. Our results provide some of the first insights into the physiological demands of bat migration and highlight key differences between bats and birds.

Innovative assessment of seasonal variations in body composition of elite soccer players with the integrated analysis DXA-BIVA

Background Body composition (BC) and its changes over time may influence performance in soccer players. BC assessment techniques are mainly based on quantitative evaluation, originating from model-based indirect estimates of FatFree Mass and Fat Mass. DXA, particularly the advanced iDXA technology, is considered to be precise enough for this kind of assessment. On the other hand, Bio Impedance Vector Analysis (BIVA) allows the direct assessment of athletes’ body composition from impedance vector (Z vector), irrespective of body weight, prediction models or hydration assumptions and may classify qualitative changes in soft tissues hydration. The objective of this study was to investigate, compare, and integrate seasonal variations of soft tissues (assessed with DXA and BIVA) in elite soccer players, playing in the Italian top level championship (national major league). Methods

Bioelectrical impedance vector analysis (BIVA) to evaluate seasonal variations in body composition of elite soccer players

Background The body composition and its variation in time can affect the performances of soccer players. The body composition measuring techniques are based on a quantitative approach founded on indirect estimations of fat mass and lean body mass. The BIVA allows us to directly see the athlete’s body composition by means of impedance vector measuring (Z vector), irrespective of weigh and body hydration status. The BIVA can classify hydration and mass variations of the soft tissues and recent observations testify that the higher the soccer player’s level, the larger the quantity of soft tissue. The purpose of this study is to observe the season variations of the soft tissues, as an indirect estimation of the nutritional condition of Italian Serie A elite male soccer players.

Seasonal variation in body composition, metabolic activity, feeding, and growth of adult krill Euphausia superba in the Lazarev Sea

We investigated physiological parameters (elemental and biochemical composition, metabolic rates, feeding activity and growth) of adult Antarctic krill in the Lazarev Sea in late spring (December), mid autumn (April) and mid winter (July and August) to evaluate proposed hypotheses of overwintering mech- anisms. Our major observations are: (1) respiration rates were reduced by 30 to 50% in autumn and win- ter, compared to values in late spring; (2) feeding activ- ity was reduced by 80 to 86% in autumn and winter, compared to late spring, at similar food concentrations; (3) feeding was omnivorous during winter; (4) with each moult, krill grew by 0.5 to 3.8% in length; (5) body lipids and, to a small extent, body proteins were consumed during winter. Adult Euphausia superba thus adopt metabolic slowdown and omnivorous feed- ing activity at low rates to survive the winter season in the Lazarev Sea. By mid autumn, metabolic activity is reduced, most likely being influenced by the Antarctic light regime, which is accompanied by a reduction in feeding activity and growth. Although at a low level, the feeding activity during winter seems to provide an important energy input.

日本海西部で漁獲されたニギスの体成分の季節変動

日本海西部で漁獲されたニギスの体成分の季節変動

Seasonal changes in body composition of Ctenomys talarum (Rodentia: Octodontidae): An herbivore subterranean rodent

Ctenomys talarum is a subterranean herbivorous rodent whose burrow systems exhibit particular characteristics, distinct from other subterranean environments. We studied seasonal variation in body composition of C. talarum in relation to energetic requirements. Body lipid content seasonally changed in C. talarum, related to reproductive cycle and thermorregulatory mechanisms. A decrease in protein body content was found only in spring. Ash content of females was lowest when most of them are in post partum estro. Observed variations in water body content could be associated with plant water content and/or metabolic regulation. Our results show the occurrence of seasonal variations in body composition in C. talarum, which could be related to the high cost of reproduction and the subterranean life style of this species.

Fat deposition and seasonal variation in body composition of red foxes (Vulpes vulpes) in Australia

We evaluated body composition of 165 adult red foxes (Vulpes vulpes) collected monthly from August 1995 to July 1996 in New South Wales, Australia. Total body fat content and estimated protein content were determined as a percentage of skinned body mass (SBM) using chemical analysis of homogenized samples. Mean percent body fat varied significantly over the year (P &lt; 0.001) and differed significantly between the sexes in each month (P = 0.039). Male body fat reserves peaked at 13% of SBM in June, prior to breeding, and female body fat peaked at 16% of SBM in July during gestation. Body fat reserves declined rapidly in both sexes from September through November, reaching average values of 3-4% SBM by the time of weaning (November). Estimates of total body protein content varied significantly over the year (P &lt; 0.001) but did not differ significantly between the sexes (P = 0.745). Protein content was lowest but stable at 21-22% of SBM from August to November and increased rapidly by December. Protein content then remained stable at 23-25% of SBM from January through July. The low body protein content in August through November corresponds to the decline in body fat reserves of foxes. These foxes appear to accumulate fat and protein reserves throughout the non-reproductive phase of their annual cycle and then deplete these stores during their reproductive period.

Fat deposition and seasonal variation in body composition of red foxes (&lt;i&gt;Vulpes vulpes&lt;/i&gt;) in Australia

Fat deposition and seasonal variation in body composition of red foxes (&lt;i&gt;Vulpes vulpes&lt;/i&gt;) in Australia

Ecophysiology of the benthic amphipod Monoporeia affinis in an open-sea area of the northern Baltic Sea:seasonal variations in body composition, with bioenergetic considerations

Ecophysiology of the benthic amphipod Monoporeia affinis in an open-sea area of the northern Baltic Sea:seasonal variations in body composition, with bioenergetic considerations

Seasonal variation in body composition and morphology of adult muskrats in central Saskatchewan, Canada

We quantified seasonal variation in body composition and morphology of adult muskrats (Ondatra zibethicus) inhabiting freshwater marsh environments in central Saskatchewan, Canada. The study areas were characterized by long and cold winters extending over six months during which muskrats were restricted to foraging under ice. A total of 162 adult muskrats were collected during nine sampling periods across the year. The large accumulation of fat reserves (16% of body mass) during winter and the concurrent decline in protein mass suggested a reduced maintenance requirement associated with the presence of energy‐rich food resources. Dietary fibre content increased significantly during mid‐summer and was manifested by changes in gut morphology. Mobilization of fat reserves during summer months by both sexes reflected high energetic demands for reproduction. Males depleted fat reserves soon after spring break‐up, while near‐exhaustion of fat reserves in females occurred 4–6 weeks later, during lactation. Pregnant females contained significantly greater fat and protein reserves compared to non‐pregnant and lactating females. The dynamics of body reserves in muskrats should be viewed as an integral part of the sex‐specific life‐history traits of this important herbivore species of marsh environments.

Fat Deposition and Seasonal Variation in Body Composition of Arctic Foxes in Svalbard

We studied the seasonal variation in body composition of arctic foxes (Alopex lagopus) to determine the adaptive significance of fat deposition in this species. Homogenates of 75 minced fox carcasses were analyzed. On a large sample of animals trapped in 1982-89, the thickness of subcutaneous fat was measured, and the amount of fat was indexed subjectively. Fat was deposited both subcutaneously and viscerally in September-October, and it reached a maximum of about 20% of the skinned carcass mass in November. The amount of fat deposited did not decline between November and March of any year. The fat deposits were depleted from March through May, reaching about 6% of the carcass mass by the summer. Fifteen percent of the trapped foxes did not have any subcutaneous or visceral fat deposits in winter

Seasonal variation in body composition of European roe deer

Seasonal variations in whole-body composition of 43 European roe deer (Capreolus capreolus L.) collected in the southeastern part of Norway were examined. Adult deer showed a defined annual cycle in both body weight and body fat reserves. Fat accumulated in September and October, reaching a maximum of 9.2% of the ingesta-free body weight in does and 10.3% in bucks, in late fall (November and December). The depletion phase started in early January and ended in April. No intersexual differences in amplitude or synchrony of body weight or fat cycle were observed. This contrasts with results in other temperate and northern cervids and could be due to differences in life strategy, particularly reproductive effort (midsummer rut, delayed implantation, and mating territories), in European roe deer.