Human Subcutaneous Adipose Tissue Sampling Using a Mini-Liposuction Technique

Studies on adipose tissue are useful in understanding metabolic and other conditions. Human subcutaneous adipose tissue is accessible. With appropriate ...

University of Stirling

Dual energy x-ray absorptiometry (DXA) is a popular tool to determine body composition (BC) in athletes, and is used for analysis of fat-free soft tissue mass (FFST) or fat mass (FM) gain/loss in response to exercise or nutritional interventions. The aim of the current study was to assess the effect of exercise-heat stress induced hypohydration (HYP, >2% of body mass (BM) loss) vs. maintenance of euhydration (EUH) on DXA estimates of BC, sum of skinfolds (SF), and impedance (IMP) measurements in athletes. Competitive athletes (23 males and 15 females) recorded morning nude BM for 7 days before the first main trial. Measurements on the first trial day were conducted in a EUH condition, and again after exercise-heat stress induced HYP. On the second trial day, fluid and electrolyte losses were replaced during exercise using a sports drink. A reduction in total BM (1.6 ± 0.4 kg; 2.3 ± 0.4% HYP) and total FFST (1.3 ± 0.4 kg), mainly from trunk (1.1 ± 0.5 kg), was observed using DXA when participants were HYP, reflecting the sweat loss. Estimated fat percent increased (0.3 ± 0.3%), however, total FM did not change (0.1 ± 0.2 kg). SF and IMP declined with HYP (losses of 1.5 ± 2.9% and 1.6 ± 3% respectively) suggesting FM loss. When EUH was maintained there were no significant changes in BM, DXA estimates, or SF values pre to post exercise, but IMP still declined. We conclude that use of DXA for FFST assessment in athletes must ensure a EUH state, particularly when considering changes associated with nutritional or exercise interventions.

Errors in dual energy x-ray absorptiometry estimation of body composition induced by hypohydration.

The identification of beverages that promote longer-term fluid retention and maintenance of fluid balance is of real clinical and practical benefit in situations in which free access to fluids is limited or when frequent breaks for urination are not desirable. The postingestion diuretic response is likely to be influenced by several beverage characteristics, including the volume ingested, energy density, electrolyte content, and the presence of diuretic agents.

A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index.

This study systematically examined the influence of carbohydrate (sucrose), sodium, and caffeine on the fluid retention potential of beverages under euhydrated conditions, using the beverage hydration index method. Three cohorts, each of 12 young, healthy, active men, ingested 1 L of beverages containing four different concentrations of a single component (sucrose, sodium, or caffeine) in a double-blind, crossover manner. Urine output was collected for the subsequent 4 hr. Cumulative urine output was lower and net fluid balance was higher after 10 and 20% sucrose beverages than 0 and 5% sucrose beverages (p < .05), and after 27 and 52 mmol/L sodium beverages than 7 and 15 mmol/L sodium beverages (p < .05). No difference in urine output or net fluid balance was apparent following ingestion of caffeine at concentrations of 0-400 mg/L (p = .83). Consequently, the calculated beverage hydration index was greater in beverages with higher sucrose or sodium content, but caffeine had no effect. No difference was observed in arginine vasopressin or aldosterone between any trials. These data highlight that the key drivers promoting differences in the fluid retention potential of beverages when euhydrated are energy density, likely through slowed fluid delivery to the circulation (carbohydrate content effect), or electrolyte content through improved fluid retention (sodium content effect). These data demonstrate that beverage carbohydrate and sodium content influence fluid delivery and retention in the 4 hr after ingestion, but caffeine up to 400 mg/L does not. Athletes and others can use this information to guide their daily hydration practices.

Sucrose and Sodium but not Caffeine Content Influence the Retention of Beverages in Humans Under Euhydrated Conditions.

 A detrimental consequence of diet-induced weight loss, common in athletes who participate in weight cutting sports, is muscle loss. Dietary omega-3 polyunsaturated fatty acids (n-3PUFA) exhibit a protective effect on the loss of muscle tissue during catabolic situations such as injury-simulated leg immobilization. This study aimed to investigate the influence of dietary n-3PUFA supplementation on changes in body composition and muscle strength following short-term diet-induced weight loss in resistance-trained men.  Twenty resistance-trained young (23 ± 1 years) men were randomly assigned to a fish oil group that supplemented their diet with 4 g n-3PUFA, 18 g carbohydrate, and 5 g protein (FO) or placebo group containing an equivalent carbohydrate and protein content (CON) over a 6 week period. During weeks 1-3, participants continued their habitual diet. During week 4, participants received all food items to control energy balance and a macronutrient composition of 50% carbohydrate, 35% fat, and 15% protein. During weeks 5 and 6, participants were fed an energy-restricted diet equivalent to 60% habitual energy intake. Body composition and strength were measured during weeks 1, 4, and 6.  The decline in total body mass (FO = -3.0 ± 0.3 kg, CON = -2.6 ± 0.3 kg), fat free mass (FO = -1.4 ± 0.3 kg, CON = -1.2 ± 0.3 kg) and fat mass (FO = -1.4 ± 0.2 kg, CON = -1.3 ± 0.3 kg) following energy restriction was similar between groups (all  > 0.05; d: 0.16-0.39). Non-dominant leg extension 1 RM increased (6.1 ± 3.4%) following energy restriction in FO ( < 0.05,  = 0.29), with no changes observed in CON ( > 0.05,  = 0.05). Dominant leg extension 1 RM tended to increase following energy restriction in FO ( = 0.09,  = 0.29), with no changes in CON ( > 0.05,  = 0.06). Changes in leg press 1 RM, maximum voluntary contraction and muscular endurance following energy restriction were similar between groups ( > 0.05,  = 0.05).  Any possible improvements in muscle strength during short-term weight loss with n-3PUFA supplementation are not related to the modulation of FFM in resistance-trained men.

Influence of Fish Oil-Derived n-3 Fatty Acid Supplementation on Changes in Body Composition and Muscle Strength During Short-Term Weight Loss in Resistance-Trained Men.

This study investigated the effect of drinking rate on fluid retention of milk and water following exercise-induced dehydration. In Part A, 12 male participants lost 1.9% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water or low-fat milk equal to the volume of sweat lost during exercise was provided. Beverages were ingested over 30 or 90 min, resulting in four beverage treatments: water 30 min, water 90 min, milk 30 min, and milk 90 min. In Part B, 12 participants (nine males and three females) lost 2.0% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water equal to the volume of sweat lost during exercise was provided. Water was ingested over 15 min (DR15), 45 min (DR45), or 90 min (DR90), with either DR15 or DR45 repeated. In both trials, nude body mass, urine volume, urine specific gravity and osmolality, plasma osmolality, and subjective ratings of gastrointestinal symptoms were obtained preexercise and every hour for 3 hr after the onset of drinking. In Part A, no effect of drinking rate was observed on the proportion of fluid retained, but milk retention was greater (p < .01) than water (water 30 min: 57% ± 16%, water 90 min: 60% ± 20%, milk 30 min: 83% ± 6%, and milk 90 min: 85% ± 7%). In Part B, fluid retention was greater in DR90 (57% ± 13%) than DR15 (50% ± 11%, p < .05), but this was within test-retest variation determined from the repeated trials (coefficient of variation: 17%). Within the range of drinking rates investigated the nutrient composition of a beverage has a more pronounced impact on fluid retention than the ingestion rate.

Effect of Drinking Rate on the Retention of Water or Milk Following Exercise-Induced Dehydration.

This review explores the effects of oestrogen and progesterone fluctuations across the menstrual cycle on fluid and electrolyte balance. The review aims to provide information on this topic for the exercising female but also for researchers working in this field. Beginning with a basic introduction to fluid and electrolyte balance, the review goes on to describe how oestrogen and progesterone have independent and integrated roles to play in the regulation of fluid and electrolyte balance. Despite evidence that oestrogen can influence the osmotic threshold for arginine vasopressin release, and that progesterone can influence aldosterone production, these actions do not appear to influence fluid retention, plasma volume changes at rest and during exercise, or electrolyte losses. However, the large inter-individual variations in hormonal fluctuations throughout the menstrual cycle may mean that specific individuals with high fluctuations could experience disturbances in their fluid and electrolyte balance. During phases of oestrogen dominance (e.g. late-follicular phase) heat dissipation is promoted, while progesterone dominance (e.g. mid-luteal phase) promotes heat conservation with overall higher basal body temperature. However, these responses do not consistently lead to any change in observed sweat rates, heat-stress, or dehydration during exercise. Finally, the literature does not support any difference in fluid retention during post-exercise rehydration periods conducted at different menstrual cycle phases. Although these mean responses largely reveal no effects on fluid and electrolyte balance, further research is required particularly in those individuals who experience high hormonal fluctuations, and greater exploration of oestrogen to progesterone interactions is warranted.

Fluid and electrolyte balance considerations for female athletes.

 The aim of this descriptive study was to characterise anthropometric variables, aerobic capacity, running performance and energy intake and expenditure of hill runners in free-living conditions, and to investigate the relationship between age, anthropometric variables, aerobic capacity and running performance.  Twenty-eight hill runners participated in this study (17 males and 11 females; aged 18-65 years). Body fat percentage estimate, sum of eight skinfolds (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh and medial calf) and maximal oxygen capacity (VOmax) were assessed in a laboratory setting. Participants also completed a timed hill run (Dumyat Hill, Scotland, ascent: 420 m, distance: 8 km) while wearing a portable gas analyzer to assess oxygen consumption (VO). Energy intake and energy expenditure were assessed in free-living conditions over three consecutive days different from the testing days through self-reported food diaries and accelerometers.  VOmax assessed in the lab (51.2 ± 7.6 ml·min·kg) showed a weak negative relationship with age [rs(23) = -0.38,  = 0.08]. Neither body fat percentage (median 12.4; IQR 10.1-17.1) nor the sum of skinfolds (median 81.8; IQR 62.4-97.8 mm) correlated with age [rs(28) = 0.001,  = 0.10 and 26 rs(28) = -0.02,  = 0.94, respectively]. The observed intensity of the hill run was 89 ± 6% of the age predicted maximum heart rate and 87 ± 9% of the VOmax observed in the lab. Hill running performance correlated with VOmax [r(21) = 0.76,  < 0.001], age [rs(26) = -0.44,  = 0.02] and with estimated body fat percentage and sum of skinfolds [rs(26) = -0.66,  < 0.001 and rs(26) = -0.49,  = 0.01, respectively]. Energy intake negatively correlated with age [rs(26) = -0.43,  = 0.03], with the overall energy intake being significantly lower than the total energy expenditure (2273 ± 550 vs. 2879 ± 510 kcal·day;  < 0.001;  = 1.05).  This study demonstrated that hill running performance is positively associated with greater aerobic capacity and negatively associated with increases in adiposity and age. Further, the study highlights that hill runners are at risk of negative energy balance.

Nidia Rodriguez-Sanchez

Physiology,
Exercise and Nutrition Research Group,
Physiology, Exercise and Nutrition Research Group

University of Stirling

Human Subcutaneous Adipose Tissue Sampling Using a Mini-Liposuction Technique

Nidia Rodriguez-Sanchez

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Physiology,Exercise and Nutrition Research Group,Physiology, Exercise and Nutrition Research Group

University of Stirling

Human Subcutaneous Adipose Tissue Sampling Using a Mini-Liposuction Technique

Physiology,
Exercise and Nutrition Research Group,
Physiology, Exercise and Nutrition Research Group