Changes in body composition in triathletes during an Ironman race

Purpose

Triathletes lose body mass during an Ironman triathlon. However, the associated body composition changes remain enigmatic. Thus, the purpose of this study was to investigate Ironman-induced changes in segmental body composition, using for the first time dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT).

Methods

Before and after an Ironman triathlon, segmental body composition and lower leg tissue mass, areas and densities were assessed using DXA and pQCT, respectively, in eight non-professional male triathletes. In addition, blood and urine samples were collected for the determination of hydration status.

Results

Body mass decreased by 1.9 ± 0.8 kg. This loss was due to 0.4 ± 0.3 and 1.4 ± 0.8 kg decrease in fat and lean mass, respectively (P < 0.01). Calf muscle density was reduced by 1.93 ± 1.04 % (P < 0.01). Hemoglobin, hematocrit, and plasma [K⁺] remained unchanged, while plasma [Na⁺] (P < 0.05), urine specific gravity and plasma and urine osmolality increased (P < 0.01).

Conclusions

The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration. The measurement of body composition with DXA and pQCT before and after an Ironman triathlon provided exact values for the loss in fat and lean mass. Consequently, these results yielded more detailed insights into tissue catabolism during ultra-endurance exercise.     

Relationships between plasma leptin levels and body composition parameters measured by different methods in postmenopausal women

The aim of this study was to determine the effects of body composition measured by different methods with different measurement errors on fasting plasma leptin level in normal body mass and obese postmenopausal women. It was hypothesized that the relationship between plasma leptin concentration and body fat is higher using more sophisticated laboratory methods (dual energy X‐ray absorptiometry, DXA) in comparison with field methods (bioelectrical impedance analysis, BIA, or skinfold thickness) for body fat measurement because of the greater precision of DXA measurements. Thirty‐five postmenopausal (55–83 years of age) healthy Estonian women were divided into two groups: BMI < 27kg/m² as non obese (n = 18) and BMI> 27kg/m² as obese (n = 17). Body composition was determined using DXA (total body, arms, legs, and trunk fat percent, fat mass, and LBM) and BIA methods. Body fat percent was significantly higher using the DXA method. Subcutaneous adipose tissue distribution was determined by measuring nine skinfold thicknesses. Body fat distribution was defined as the ratio of waist‐to‐hip (WHR) and waist‐to‐thigh (WTR) circumferences. Leptin was determined by means of radioimmunoassays. Leptin concentration was not significantly different between groups (19.0 ± 13.3 and 21.5 ± 21.5ng/ml in non obese and obese groups, respectively). Body fat percent and fat weight measured by DXA or BIA methods and all measured skinfold thickness values, except biceps and abdominal, were higher in obese women. Body height did not correlate significantly with leptin concentrations. The relationships between leptin concentration were highest with body weight (r = 0.67) and BMI (r = 0.73) values in the obese group. All measured body fat parameters using DXA or BIA methods correlated significantly with plasma leptin concentration in the obese group. LBM did not influence the leptin concentration in postmenopausal women. Stepwise multiple regression analysis indicated that the body fat percent measured using the DXA method was highly related to plasma leptin concentration in the obese group (63.2%; R² × 100). When absolute fat mass parameters were considered, leptin concentration was related to the mass of arms fat tissue in the obese group of women (62.3%). Body fat percent measured by BIA was highly related to plasma leptin concentration in the obese group (63.3%). Only biceps skinfold thickness was related to leptin concentration (22.5% and 58.9%, in the nonobese and obese groups, respectively) from the nine measured skinfold thicknesses. WHR and WTR did not reflect leptin concentration in different groups of postmenopausal women. It was concluded that different methods of body composition estimation generate different correlations with plasma leptin concentration. Body fat percent and especially fat mass measured by DXA are the main predictors relating to plasma leptin concentration in obese, but not in nonobese, postmenopausal women. In addition, fat mass in arms measured by DXA and biceps skinfold thickness were also highly related to leptin concentration. Am. J. Hum. Biol. 15:628–636, 2003. © 2003 Wiley‐Liss, Inc.     

Multiple dosing strategies with acetyl L-carnitine (ALCAR) fail to alter age-related hearing loss in the Fischer 344/NHsd rat

Background

The aim of this study was to compare body composition results from bioelectrical spectroscopy (BIS) with results from dual energy X-ray absorptiometry (DXA) in a population of male elite athletes. Body composition was assessed using DXA (Lunar Prodigy, GE Lunar Corp., Madison, USA) and BIS (Hydra 4200, Xitron Technologies Inc, San Diego, California, USA) at the same occasion. Agreement between methods was assessed using paired t-tests and agreement-plots.

Results

Thirty-three male elite athletes (soccer and ice hockey) were included in the study. The results showed that BIS underestimates the proportion of fat mass by 4.6% points in the ice hockey players. In soccer players the BIS resulted in a lower mean fat mass by 1.1% points. Agreement between the methods at the individual level was highly variable.

Conclusion

Body composition results assessed by BIS in elite athletes should be interpreted with caution, especially in individual subjects. BIS may present values of fat mass that is either higher or lower than fat mass assessed by DXA, independent of true fat content of the individual.     

Effects of high vs. moderate exercise intensity during interval training on lipids and adiponectin levels in obese young females

Purpose

We investigate the effects of 12-week interval training of moderate- or high-intensity exercise on blood lipids and plasma levels of adiponectin.

Methods

Thirty-four obese adolescent females [age = 15.9 ± 0.3 years; BMI and BMI-Z-score = 30.8 ± 1.6 kg/m² and 3 ± 0.3, respectively], were randomized to high-intensity interval training (HIIT, n = 11), moderate-intensity interval training (MIIT, n = 11), or a control group (CG, n = 12). Maximal oxygen uptake ( $\mathop V\limits^{.} {\text{O}}_{{2{\text{peak}}}}$ V . O 2 peak ), maximal aerobic speed (MAS), plasma lipids and adiponectin levels were measured in all subjects before and after training.

Results

Following the training program, in both training groups, body mass, BMI-Z-score, and percentage body fat (% BF) decreased, while $\mathop V\limits^{.} {\text{O}}_{{2{\text{peak}}}}$ V . O 2 peak and MAS increased. Low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and adiponectin levels were positively altered (?12.6 and ?7.4 %; 6.3 and 8.0 %; 35.8 and 16.2 %; high to moderate training program, respectively). Waist circumference, triglyceride and total cholesterol decreased only in HIIT group (?3.5; ?5.3 and ?7.0 %, respectively, in all P < 0.05). Significant decrease in the usual index of insulin resistance (HOMA-IR) occurred in HIIT and MIIT groups (?29.2 ± 5.3 and ?18.4 ± 8.6 %, respectively; P < 0.01).

Conclusion

The results show that HIIT positively changes blood lipids and adiponectin variables in obese adolescent girls, resulting in improved insulin sensitivity, as attested by a lower HOMA-IR, and achieving better results compared to moderate-intensity exercise.     

The effect of arm training on thermoregulatory responses and calf volume during upper body exercise

Purpose

The smaller muscle mass of the upper body compared to the lower body may elicit a smaller thermoregulatory stimulus during exercise and thus produce novel training-induced thermoregulatory adaptations. Therefore, the principal aim of the study was to examine the effect of arm training on thermoregulatory responses during submaximal exercise.

Methods

Thirteen healthy male participants (Mean ± SD age 27.8 ± 5.0 years, body mass 74.8 ± 9.5 kg) took part in 8 weeks of arm crank ergometry training. Thermoregulatory and calf blood flow responses were measured during 30 min of arm cranking at 60 % peak power (W _peak) pre-, and post-training and post-training at the same absolute intensity as pre-training. Core temperature and skin temperatures were measured, along with heat flow at the calf, thigh, upper arm and chest. Calf blood flow using venous occlusion plethysmography was performed pre- and post-exercise and calf volume was determined during exercise.

Results

The upper body training reduced aural temperature (0.1 ± 0.3 °C) and heat storage (0.3 ± 0.2 J g^?1) at a given power output as a result of increased whole body sweating and heat flow. Arm crank training produced a smaller change in calf volume post-training at the same absolute exercise intensity (?1.2 ± 0.8 % compared to ?2.2 ± 0.9 % pre-training; P < 0.05) suggesting reduced leg vasoconstriction.

Conclusion

Training improved the main markers of aerobic fitness. However, the results of this study suggest arm crank training additionally elicits physiological responses specific to the lower body which may aid thermoregulation.     

Metabolic adaptations in skeletal muscle,adipose tissue,and whole-body oxidative capacity in response to resistance training

Purpose

The effects of resistance training on mitochondrial biogenesis and oxidative capacity in skeletal muscle are not fully characterized, and even less is known about alterations in adipose tissue. We aimed to investigate adaptations in oxidative metabolism in skeletal muscle and adipose tissue after 8 weeks of heavy resistance training in apparently healthy young men.

Methods

Expression of genes linked to oxidative metabolism in the skeletal muscle and adipose tissue was assessed before and after the training program. Body composition, peak oxygen uptake (VO_{2 peak}), fat oxidation, activity of mitochondrial enzyme in muscle, and serum adiponectin levels were also determined before and after resistance training.

Results

In muscle, the expression of the genes AdipoR1 and COX4 increased after resistance training (9 and 13 %, respectively), whereas the expression levels of the genes PGC-1α, SIRT1, TFAM, CPT1b, and FNDC5 did not change. In adipose tissue, the expression of the genes SIRT1 and CPT1b decreased after training (20 and 23 %, respectively). There was an increase in lean mass (from 59.7 ± 6.1 to 61.9 ± 6.2 kg), VO_{2 peak} (from 49.7 ± 5.5 to 56.3 ± 5.0 ml/kg/min), and fat oxidation (from 6.8 ± 2.1 to 9.1 ± 2.7 mg/kg fat-free mass/min) after training, whereas serum adiponectin levels decreased significantly and enzyme activity of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase did not change.

Conclusion

Despite significant increases in VO_{2 peak}, fat oxidation, and lean mass following resistance training, the total effect on gene expression and enzyme activity linked to oxidative metabolism was moderate.     

The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass,strength, and power in resistance-trained individuals: a randomized,double-blind,placebo-controlled study

Introduction

Studies utilizing beta-hydroxy-beta-methylbutyrate (HMB) supplementation in trained populations are limited. No long-term studies utilizing HMB free acid (HMB-FA) have been conducted. Therefore, we investigated the effects of 12 weeks of HMB-FA supplementation on skeletal muscle hypertrophy, body composition, strength, and power in trained individuals. We also determined the effects of HMB-FA on muscle damage and performance during an overreaching cycle.

Methods

A three-phase double-blind, placebo- and diet-controlled randomized intervention study was conducted. Phase 1 was an 8-week-periodized resistance-training program; Phase 2 was a 2-week overreaching cycle; and Phase 3 was a 2-week taper. Muscle mass, strength, and power were examined at weeks 0, 4, 8, and 12 to assess the chronic effects of HMB-FA; and assessment of these, as well as cortisol, testosterone, and creatine kinase (CK) was performed at weeks 9 and 10 of the overreaching cycle.

Results

HMB-FA resulted in increased total strength (bench press, squat, and deadlift combined) over the 12-week training (77.1 ± 18.4 vs. 25.3 ± 22.0 kg, p < 0.001); a greater increase in vertical jump power (991 ± 168 vs. 630 ± 167 W, p < 0.001); and increased lean body mass gain (7.4 ± 4.2 vs. 2.1 ± 6.1 kg, p < 0.001) in HMB-FA- and placebo-supplemented groups, respectively. During the overreaching cycle, HMB-FA attenuated increases in CK (?6 ± 91 vs. 277 ± 229 IU/l, p < 0.001) and cortisol (?0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl, p < 0.003) in the HMB-FA- and placebo-supplemented groups, respectively.

Conclusions

These results suggest that HMB-FA enhances hypertrophy, strength, and power following chronic resistance training, and prevents decrements in performance following the overreaching.     

Early-phase musculoskeletal adaptations to different levels of eccentric resistance after 8 weeks of lower body training

Purpose

Eccentric muscle actions are important to the development of muscle mass and strength and may affect bone mineral density (BMD). This study’s purpose was to determine the relative effectiveness of five different eccentric:concentric load ratios to increase musculoskeletal parameters during early adaptations to resistance training.

Methods

Forty male subjects performed a supine leg press and calf press training program 3 days week^?1 for 8 weeks. Subjects were matched for pre-training leg press 1-repetition maximum strength (1-RM) and randomly assigned to one of five training groups. Concentric training load (% 1-RM) was constant across groups, but within groups, eccentric load was 0, 33, 66, 100, or 138 % of concentric load. Muscle mass (dual energy X-ray absorptiometry; DXA), strength (1-RM), and BMD (DXA) were measured pre- and post-training. Markers of bone metabolism were assessed pre-, mid- and post-training.

Results

The increase in leg press 1-RM in the 138 % group (20 ± 4 %) was significantly greater (P < 0.05) than the 0 % (8 ± 3 %), 33 % (8 ± 5 %) and 66 % (8 ± 4 %) groups, but not the 100 % group (13 ± 6 %; P = 0.15). All groups, except the 0 % group, increased calf press 1-RM (P < 0.05). Leg lean mass and greater trochanter BMD were increased only in the 138 % group (P < 0.05).

Conclusions

Early-phase adaptations to eccentric overload training include increases in muscle mass and site-specific increases in BMD and muscle strength which are not present or are less with traditional and eccentric underload training. Eccentric overload provides a robust musculoskeletal stimulus that may benefit bedridden patients, individuals recovering from injury or illness, and astronauts during spaceflight.     

Muscle strength and its relationship with skeletal muscle mass indices as determined by segmental bio-impedance analysis

Purpose

Despite increasing interest in bio-impedance analysis (BIA) for estimation of segmental skeletal muscle mass (SMM), published results have not been entirely convincing. Furthermore, a better understanding of the relationship between muscle strength and SMM will be useful in interpreting outcomes of physical/training interventions particularly in groups with diverse body sizes (e.g. men vs women). This study aimed to measure SMM in the upper body (upper extremity and torso), to determine its correlation with muscle strength and to examine the effects of gender on muscle strength–muscle mass relationship.

Methods

Segmental (upper extremity and torso) SMM and muscle strength in five distinct shoulder planes (forward flexion, abduction in scapular plane, abduction in coronal plane, internal and external rotation) were measured in 45 healthy participants (22 males, 23 females) with mean age 30.3 years. Statistical analysis included independent t tests, Pearson correlation, and multiple regression analysis.

Results

Men and women differed significantly in body mass (BMI: 25.9 ± 4.3 vs 23 ± 3.6) and SMM (p < 0.01). A strong relationship correlation was found between the five shoulder strength measurements and upper extremity SMM (r = 0.66–0.80, p < 0.01), which was not affected by gender. There was a significant gender difference (p < 0.01) in absolute shoulder strength, but not after normalisation to the SMM.

Conclusion

BIA-estimated SMM of upper extremity and torso was highly correlated with upper extremity (shoulder) strength independent of gender. SMM may, therefore, be useful for the normalisation of muscle strength allowing size-independent comparisons of muscle strength in individuals with diverse physical characteristics.     

Periodized resistance training with and without supplementation improve body composition and performance in older men

Purpose

To examine the effects of 12 weeks of periodized resistance training (RT) with and without combined creatine and whey protein supplementation on changes in body composition, muscular strength, and functional performance.

Methods

Twenty-two male volunteers (68.1 ± 6.1 years) were randomly assigned to one of three groups: RT plus supplementation (RTS, n = 7); RT only (RT, n = 7); or control (C, n = 8). RTS consumed 0.3 g/kg/day of creatine for 5 days followed by 0.07 g/kg/day. RTS also consumed one 35 g liquid protein ready-to-drink daily. RT and RTS trained 3 days/week.

Results

Following 12 weeks of training, there were no significant differences in the main measured outcome variables between RT and RTS. RTS increased relative (% change) lean body mass (LBM, 3.3 ± 3.1 %) compared with C (p = 0.01). Compared to baseline, RT increased LBM at week 6 (60.2 ± 8.3 to 61.6 ± 9.4 kg; p < 0.05), and decreased fat mass (20.8 ± 4.2 to 19.0 ± 3.9 kg; p = 0.05) and percentage body fat at week 12 (25.7 ± 3.8 to 23.8 ± 4.0 %; p = 0.05); RTS increased LBM at week 6 (p < 0.01) and week 12 (56.4 ± 4.3 to 58.2 ± 3.4 kg; p < 0.01), and decreased percentage body fat at week 12 (23.9 ± 4.4 to 22.0 ± 4.4 %; p < 0.01). In addition, compared to C, relative bench press 1-RM increased for RTS (72.4 ± 62.2 %; p < 0.01) and RT (50.1 ± 21.5 %; p = 0.05); relative leg press 1-RM increased for RTS (129.6 ± 39.4 %; p < 0.0001) and RT (112.9 ± 22.7 %; p < 0.0001); RTS increased relative Margaria stair-climbing power (38.3 ± 30.4 %; p < 0.05); and, relative 400-m walk time decreased for RT (?11 ± 9.2 %; p < 0.05) and RTS (?9.6 ± 9.4 %; p = 0.05). RT increased estimated VO_2Max at week 6 (p < 0.01) and 12 (34.6 ± 1.9 to 36.4 ± 2.7 ml/kg/min; p = 0.01) compared to baseline. Lastly, RTS increased estimated VO_2Max at week 12 (36.3 ± 2.7 to 37.5 ± 3.3 ml/kg/min; p = 0.05) compared to baseline.

Conclusion

Creatine and whey protein supplementation may not provide additional benefits in older adults performing periodized RT to augment muscular and functional performance.     

Associations of objectively measured sedentary behavior,light activity,and markers of cardiometabolic health in young women

Purpose

To investigate the associations among objectively measured sedentary behavior, light physical activity, and markers of cardiometabolic health in young women.

Methods

Cardiovascular disease risk factors, homeostasis model assessment for insulin resistance (HOMA-IR), lipid accumulation product, and inflammatory markers were measured in 50 young, adult women. Accelerometers were worn over 7 days to assess sedentary time (<150 counts min^?1), light physical activity (150–2,689 counts min^?1), and moderate-to-vigorous physical activity (MVPA; ≥2,690 counts min^?1). Multivariate regression examined independent associations of sedentary behavior and light physical activity with cardiometabolic health. Covariates included MVPA, cardiorespiratory fitness (VO_2peak) and body mass, and body composition.

Results

Sedentary behavior was associated with triglycerides (p = 0.03) and lipid accumulation product (p = 0.02) independent of MVPA. These associations were attenuated by VO_2peak and body mass or body composition (p ≥ 0.05). Light physical activity was independently associated with triglycerides and lipid accumulation product after adjustment for all covariates (p < 0.05). The association between light physical activity and HOMA-IR was independent of MVPA (p = 0.02) but was attenuated by VO_2peak and body mass or body composition (p > 0.05).

Conclusions

Sedentary behavior and light physical activity were independently associated with markers of cardiometabolic health in young, adult women. Our data suggest that VO_2peak and body composition may be important mediators of these associations. Decreasing sedentary behavior and increasing light physical activity may be important for maintaining cardiometabolic health in young, adult women.     

Separate and combined effects of 21-day bed rest and hypoxic confinement on body composition

Purpose

This study tested the hypothesis that hypoxia exacerbates reductions in body mass observed during unloading.

Methods

To discern the separate and combined effects of simulated microgravity and hypoxia, 11 healthy males underwent three 21-day campaigns in a counterbalanced fashion: (1) normoxic bed rest (NBR; F_iO₂ = 0.209; P_iO₂ = 133.1 ± 0.3); (2) hypoxic ambulatory confinement (HAMB; F_iO₂ = 0.141 ± 0.004; P_iO₂ = 90.0 ± 0.4; ~4,000 m); and (3) hypoxic bed rest (HBR; F_iO₂ = 0.141 ± 0.004; P_iO₂ = 90.0 ± 0.4). The same dietary menu was applied in all campaigns. Targeted energy intakes were estimated individually using the Harris–Benedict equation taking into account whether the subjects were bedridden or ambulatory. Body mass and water balance were assessed throughout the campaigns. Whole body and regional body composition was determined before and after the campaigns using dual-energy X-ray absorptiometry. Before and during the campaigns, indirect calorimetry and visual analogue scores were employed to assess the resting energy expenditure (REE) and perceived appetite sensations, respectively.

Results

Energy intakes were lower than targeted in all campaigns (NBR: ?5 %; HAMB: ?14 %; HBR: ?6 %; P < 0.01). Body mass significantly decreased following all campaigns (NBR: ?3 %; HAMB: ?4 %; HBR: ?5 %; P < 0.01). While fat mass was not significantly altered, the whole body fat free mass was reduced (NBR: ?4 %; HAMB: ?5 %; HBR: ?5 %; P < 0.01), secondary to lower limb fat-free mass reduction. Water balance was comparable between the campaigns. No changes were observed in REE and perceived appetite.

Conclusions

Exposure to simulated altitude of ~4,000 m does not seem to worsen the whole body mass and fat-free mass reductions or alter resting energy expenditure and appetite during a 21-day simulated microgravity.     

Assessment of extracellular dehydration using saliva osmolality

Introduction

When substantial solute losses accompany body water an isotonic hypovolemia (extracellular dehydration) results. The potential for using blood or urine to assess extracellular dehydration is generally poor, but saliva is not a simple ultra-filtrate of plasma and the autonomic regulation of salivary gland function suggests the possibility that saliva osmolality (Sosm) may afford detection of extracellular dehydration via the influence of volume-mediated factors.

Purpose

This study aimed to evaluate the assessment of extracellular dehydration using Sosm. In addition, two common saliva collection methods and their effects on Sosm were compared.

Methods

Blood, urine, and saliva samples were collected in 24 healthy volunteers during paired euhydration and dehydration trials. Furosemide administration and 12 h fluid restriction were used to produce extracellular dehydration. Expectoration and salivette collection methods were compared in a separate group of eight euhydrated volunteers. All comparisons were made using paired t-tests. The diagnostic potential of body fluids was additionally evaluated.

Results

Dehydration (3.1 ± 0.5 % loss of body mass) decreased PV (?0.49 ± 0.12 L; ?15.12 ± 3.94 % change), but Sosm changes were marginal (<10 mmol/kg) and weakly correlated with changes in absolute or relative PV losses. Overall diagnostic accuracy was poor (AUC = 0.77–0.78) for all body fluids evaluated. Strong agreement was observed between Sosm methods (Expectoration: 61 ± 10 mmol/kg, Salivette: 61 ± 8 mmol/kg, p > 0.05).

Conclusions

Extracelluar dehydration was not detectable using plasma, urine, or saliva measures. Salivette and expectoration sampling methods produced similar, consistent results for Sosm, suggesting no methodological influence on Sosm.     

Small-sided games training reduces CRP,IL-6 and leptin in sedentary,middle-aged men

Purpose

Long-term physical activity is reported to improve chronic systemic inflammation, which provides protection against the ensuing development of chronic disease. Accordingly, the present study assessed changes in pro- and anti-inflammatory cytokines, aerobic capacity and body composition following 8 weeks of either small-sided games (SSG) or cycling (CYC) training compared to a sedentary control (CON) condition.

Methods

Thirty-three middle-aged, sedentary men were randomized into CYC (n = 11), SSG (n = 11), or CON (n = 11) conditions. The CYC and SSG conditions trained 3 days/week for 8 weeks, whilst CON maintained habitual activity and dietary patterns. Pre- and post-intervention testing included a dual-energy X-ray absorptiometry scan, sub-maximal (80 % maximal heart rate) aerobic capacity (VO₂) and fasting venous blood. Venous blood measures for pro-inflammatory markers included C-reactive protein (CRP), interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and leptin; anti-inflammatory markers included IL-10, IL-1 receptor agonist, and adiponectin.

Results

Both CYC and SSG increased submaximal power output and VO₂ (P < 0.05), decreased total body fat-mass (TB-FM; P < 0.05), and CRP (SSG, ?0.45 ± 0.42 mg L^?1; P = 0.008; CYC, ?0.44 ± 0.59 mg L^?1; P = 0.02). Only SSG increased total body fat-free mass (TB-FFM; +1.1 ± 1.2 kg; P = 0.001) and decreased concentration of plasma IL-6 (?0.69 ± 0.62 pg mL^?1; P = 0.002) and leptin (?2,212 ± 2,531 ng mL^?1; P = 0.014).

Conclusion

Cycling and SSG training were both effective at improving CRP, VO₂ and TB-FM. Furthermore, SSG training has also shown to be an effective training approach in reducing IL-6 and leptin and increasing muscle mass within sedentary, middle-aged men.     

Influence of the world’s most challenging mountain ultra-marathon on energy cost and running mechanics

Purpose

To examine the effects of the world’s most challenging mountain ultra-marathon (Tor des Géants^® 2012) on the energy cost of three types of locomotion (cycling, level and uphill running) and running kinematics.

Methods

Before (pre-) and immediately after (post-) the competition, a group of ten male experienced ultra-marathon runners performed in random order three submaximal 4-min exercise trials: cycling at a power of 1.5 W kg^?1 body mass; level running at 9 km h^?1 and uphill running at 6 km h^?1 at an inclination of +15 % on a motorized treadmill. Two video cameras recorded running mechanics at different sampling rates.

Results

Between pre- and post-, the uphill-running energy cost decreased by 13.8 % (P = 0.004); no change was noted in the energy cost of level running or cycling (NS). There was an increase in contact time (+10.3 %, P = 0.019) and duty factor (+8.1 %, P = 0.001) and a decrease in swing time (?6.4 %, P = 0.008) in the uphill-running condition.

Conclusion

After this extreme mountain ultra-marathon, the subjects modified only their uphill-running patterns for a more economical step mechanics.     

Central and peripheral adjustments during high-intensity exercise following cold water immersion

Purpose

We investigated the acute effects of cold water immersion (CWI) or passive recovery (PAS) on physiological responses during high-intensity interval training (HIIT).

Methods

In a crossover design, 14 cyclists completed 2 HIIT sessions (HIIT1 and HIIT2) separated by 30 min. Between HIIT sessions, they stood in cold water (10 °C) up to their umbilicus, or at room temperature (27 °C) for 5 min. The natural logarithm of square-root of mean squared differences of successive R–R intervals (ln rMSSD) was assessed pre- and post-HIIT1 and HIIT2. Stroke volume (SV), cardiac output ( $ \dot{Q} $ ), O₂ uptake ( $ \dot{V} $ O₂), total muscle hemoglobin (t _Hb) and oxygenation of the vastus lateralis were recorded (using near infrared spectroscopy); heart rate, $ \dot{Q} $ , and $ \dot{V} $ O₂ on-kinetics (i.e., mean response time, MRT), muscle de-oxygenation rate, and anaerobic contribution to exercise were calculated for HIIT1 and HIIT2.

Results

ln rMSSD was likely higher [between-trial difference (90 % confidence interval) [+13.2 % (3.3; 24.0)] after CWI compared with PAS. CWI also likely increased SV [+5.9 % (?0.1; 12.1)], possibly increased $ \dot{Q} $ [+4.4 % (?1.0; 10.3)], possibly slowed $ \dot{Q} $ MRT [+18.3 % (?4.1; 46.0)], very likely slowed $ \dot{V} $ O₂ MRT [+16.5 % (5.8; 28.4)], and likely increased the anaerobic contribution to exercise [+9.7 % (?1.7; 22.5)].

Conclusion

CWI between HIIT slowed $ \dot{V} $ O₂ on-kinetics, leading to increased anaerobic contribution during HIIT2. This detrimental effect of CWI was likely related to peripheral adjustments, because the slowing of $ \dot{V} $ O₂ on-kinetics was twofold greater than that of central delivery of O₂ (i.e., $ \dot{Q} $ ). CWI has detrimental effects on high-intensity aerobic exercise performance that persist for ≥45 min.     

Age-related volumetric changes in pancreas: a stereological study on computed tomography

Purpose

(1) To explore age-related changes in the volume of the pancreas on computed tomography (CT) images calculated by the method of Cavalieri. (2) To investigate the relationship between these changes and body mass index (BMI), gender, abdominal diameter, abdominal skinfold thickness.

Methods

We retrospectively reviewed abdominal CT examinations of 272 adults between the ages of 20–88 years. There were seven groups of patients, with 40 patients (only ninth decade has 32 patients) for each decade.

Results

Pancreatic volume (PV) was found to be 63.68 ± 15.08 cm³ in females, 71.75 ± 15.99 cm³ in males (mean value of both groups, 67.71 ± 16.03 cm³). Maximum value of PV was found in the fourth decade in females, males and also for mean of both groups (73.50, 84.21 and 78.85 cm³, respectively). PV remained constant until ~60 years of age. Thereafter, it gradually decreased in both genders. There was a negative correlation between PV and age (p < 0.001, r: ?0.473). We found positive correlation between PV and BMI, sagittal abdominal diameter (SAD), transverse abdominal diameter (TAD), anterior subcutaneous adipose tissue thicknesses (ASAT), posterior subcutaneous adipose tissue thicknesses (PSAT), bilateral subcutaneous adipose tissue thicknesses (BSAT).

Conclusions

Quantitative data may allow clinicians to better estimate age-related PV changes and help them in decision making.     

Early gain in body mass with continuous positive airway pressure therapy for obstructive sleep apnea

Study objectives

Many clinicians believe that continuous positive airway pressure (CPAP) therapy of obstructive sleep apnea (OSA) is associated with a decrease in body mass, but to date, studies generally suggest long-term stability in body mass after 1 year. We have seen body mass increase after 4 weeks of treatment with CPAP in most patients with OSA. In this study, we test the hypothesis that therapy of OSA with CPAP produces a short-term gain in body mass, and look for physiological correlates to suggest an underlying mechanism.

Methods

Retrospective analysis of 218 consecutive patients treated for sleep apnea at a community-based sleep center.

Results

A total of 152 patients met the criteria for study conclusion. After 1 month of CPAP treatment, 119 subjects (78%) gained mass, including 81% of men and 73% of women. As a group, subjects on CPAP gained 1.4±2.5 kg (mean±SD). The Epworth Sleepiness Scale was reduced after 1 month of CPAP therapy. There was no correlation between gain in body mass and measured parameters. A subgroup of 71 patients remained on therapy. They demonstrated a gain in mass at 4 weeks, which did not persist at 6 months.

Conclusions

CPAP treatment of OSA is associated with gain in body mass at 1 month but not 6 months of therapy. The nature of this gain in mass remains unknown. We believe the gain is due to increased vascular volume, and might represent an early marker of physiological benefit of CPAP. This article includes a review of potential mechanisms for early increase in body mass with CPAP.     

Creatine supplementation post-exercise does not enhance training-induced adaptations in middle to older aged males

Purpose

The present study evaluated the effects of creatine monohydrate (CrM) consumption post-exercise on body composition and muscle strength in middle to older males following a 12-week resistance training program.

Methods

In a double-blind, randomized trial, 20 males aged between 55 and 70 years were randomly assigned to consume either CrM-carbohydrate (CHO) [20 g days^?1 CrM + 5 g days^?1 CHO × 7 days, then 0.1 g kg^?1 CrM + 5 g CHO on training days (average dosage of ~8.8 g)] or placebo CHO (20 g days^?1 CHO × 7 days, then 5 g CHO on training days) while participating in a high intensity resistance training program [3 sets × 10 repetitions at 75 % of 1 repetition maximum (1RM)], 3 days weeks^?1 for 12 weeks. Following the initial 7-day “loading” phase, participants were instructed to ingest their supplement within 60 min post-exercise. Body composition and muscle strength measurements, blood collection and vastus lateralis muscle biopsy were completed at 0, 4, 8 and 12 weeks of the supplement and resistance training program.

Results

A significant time effect was observed for 1RM bench press (p = 0.016), leg press (p = 0.012), body mass (p = 0.03), fat-free mass (p = 0.005) and total myofibrillar protein (p = 0.005). A trend for larger muscle fiber cross-sectional area in the type II fibers compared to type I fibers was observed following the 12-week resistance training (p = 0.08). No supplement interaction effects were observed.

Conclusion

Post-exercise ingestion of creatine monohydrate does not provide greater enhancement of body composition and muscle strength compared to resistance training alone in middle to older males.