Search Results

You are looking at 221 - 230 of 930 items for :

  • "body composition" x
Clear All
Restricted access

Gary J. Slater, Anthony J. Rice, David Jenkins, Jason Gulbin and Allan G. Hahn

To strengthen the depth of lightweight rowing talent, we sought to identify experienced heavyweight rowers who possessed physique traits that predisposed them to excellence as a lightweight. Identified athletes (n = 3) were monitored over 16 wk. Variables measured included performance, anthropometric indices, and selected biochemical and metabolic parameters. All athletes decreased their body mass (range 2.0 to 8.0 kg), with muscle mass accounting for a large proportion of this (31.7 to 84.6%). Two athletes were able to maintain their performance despite reductions in body mass. However, performance was compromised for the athlete who experienced the greatest weight loss. In summary, smaller heavyweight rowers can successfully make the transition into the lightweight category, being nationally competitive in their first season as a lightweight.

Restricted access

Eric D.B. Goulet, Michel O. Mélançon, Mylène Aubertin Leheudre and Isabelle J. Dionne

It is unclear whether long-term aerobic (AT) or resistance (RT) training can improve insulin sensitivity (IS) beyond the residual effect of the last training bout in older women (54–78 years). Therefore, a group of nonobese, healthy older women underwent 6 months of AT (n = 8) or RT (n = 10), and the authors measured IS 4 days after the last training bouts using the hyperinsulinemic-euglycemic clamp technique. Women trained 3 days/week. AT consisted of 25- to 60-min sessions of walking/jogging at 60–95% of maximal heart rate. RT consisted of three sets of nine exercises repeated 10 times at 80% of 1 repetition maximum. AT decreased fat mass, whereas both AT and RT increased fat-free mass. Neither training program, however, improved absolute or relative rates of glucose disposal. The authors therefore concluded that nonobese, healthy older women should perform AT or RT on a daily basis in order to improve IS and maintain the improvement.

Restricted access

Alison Schinkel-Ivy, Timothy A. Burkhart and David M. Andrews

To date, there has not been a direct examination of the effect that tissue composition (lean mass/muscle, fat mass, bone mineral content) differences between males and females has on how the tibia responds to impacts similar to those seen during running. To evaluate this, controlled heel impacts were imparted to 36 participants (6 M and 6 F in each of low, medium and high percent body fat [BF] groups) using a human pendulum. A skin-mounted accelerometer medial to the tibial tuberosity was used to determine the tibial response parameters (peak acceleration, acceleration slope and time to peak acceleration). There were no consistent effects of BF or specific tissue masses on the un-normalized tibial response parameters. However, females experienced 25% greater peak acceleration than males. When normalized to lean mass, wobbling mass, and bone mineral content, females experienced 50%, 62% and 70% greater peak acceleration, respectively, per gram of tissue than males. Higher magnitudes of lean mass and bone mass significantly contributed to decreased acceleration responses in general.

Restricted access

Michael J. Davies, Gail P. Dalsky and Paul M. Vanderburgh

This study employed allometry to scale maximal oxygen uptake (V̇O2 max) by body mass (BM) and lean body mass (LBM) in healthy older men. Ratio standards (ml · kg−1 · min−1) derived by dividing absolute V̇O2 max (L · min−1) by BM or LBM often fail to control for the body size variable. The subjects were 73 older men (mean ± SD: age = 69.7 ± 4.3 yrs, BM = 80.2 ± 9.6 kg, height = 174.1 ± 6.9 cm). V̇O2 max was assessed on a treadmill with the modified Balke protocol (V̇O2 max = 2.2 ± 0.4 L · min−1). Body fat (27.7 ± 6.4%) was assessed with dual energy x-ray absorptiometry. Allometry applied to BM and V̇O2 max determined the BM exponent to be 0.43, suggesting that heavier older men are being penalized when ratio standards are used. Allometric scaling applied to LBM revealed the LBM exponent to be 1.05 (not different from the ratio standard exponent of 1.0). These data suggest that the use of ratio standards to evaluate aerobic fitness in older men penalized fatter older men but not those with higher LBM.

Restricted access

Takashi Kamijo and Masami Murakami

Background:

Lifestyle-related diseases among middle-age and elderly people have become serious problems. Underlying causes might be related to the changes in the lifestyle including the absence of regular physical exercise.

Methods:

To clarify the significance of regular physical exercise to prevent lifestyle-related diseases, we studied motor functions and blood chemistry examinations in middle-age and elderly women (over 40 years old) who performed regular physical exercise for 2 years (exercise group) and those who initially did not (control group).

Results:

In study 1, VO2max significantly increased in the exercise group compared with the control group in the under 60 years old groups. In the over 60 years old groups, VO2max, foot balance, and HDL-cholesterol significantly increased. Plasma glucose at 120 minutes after the 75 g oral glucose tolerance test, fasting insulin, homeostasis model assessment (HOMA-R), and high sensitivity C-reactive protein (hsCRP) significantly decreased in the exercise group compared with the control group. In study 2, a 1-year exercise program significantly improved physical functions and biochemical markers in the control group.

Conclusion:

These results suggest that regular physical exercise might help to maintain sound motor functions and decrease insulin resistance and a risk for arteriosclerosis.

Restricted access

Nathanael G. Mitchell, Justin B. Moore, Wendy S. Bibeau and Kathleen M. Rudasill

Background:

Levels of physical activity decline throughout childhood. Children’s physical self-perceptions have been found to relate to their physical activity. Understanding the relationships among physical self-perceptions, obesity, and physical activity could have important implications for interventions in children.

Methods:

The current study investigated the moderating effect of cardiovascular fitness (CVF, heart rate recovery from a 3-minute step test) on the relationship between obesity (BMI, waist circumference) and physical self-perceptions (athletic competence, physical appearance) in 104 fourth- and fifth-grade children from a small rural community.

Results:

Hierarchical regression analyses indicated that CVF moderated the relations between BMI and waist circumference on athletic competence. For children with lower fitness, higher waist circumference was associated with lower athletic competence, while for children with higher fitness levels, higher BMI was associated with higher athletic competence. Results also indicated that both BMI and waist circumference were negatively related to physical appearance. CVF moderated these relations such that only children with lower fitness, greater BMI and waist circumference was associated with poorer physical appearance scores.

Conclusions:

Implications include the need for support of fitness programs to promote psychological well-being and to investigate the relationship between obesity and physical self-perceptions within the context of fitness.

Restricted access

Barbara Coiro Spessato, Carl Gabbard and Nadia C. Valentini

Our goal was to investigate the role of body mass index (BMI) and motor competence (MC) in children’s physical activity (PA) levels during physical education (PE) classes. We assessed PA levels of 5-to-10-year old children (n = 264) with pedometers in four PE classes. MC was assessed using the TGMD-2 and BMI values were classified according to CDC guidelines. We found small-to-moderate positive correlations between MC and PA; BMI was not significantly correlated with MC and PA. The linear regression model indicated that overall MC was a better predictor of PA than BMI. Our results suggest that children with higher MC find a way to be more active even in a structured setting such as a PE class. Our findings draw attention to the importance of promoting MC, especially for children with high BMI.

Restricted access

Brett S. Nickerson, Michael R. Esco, Phillip A. Bishop, Brian M. Kliszczewicz, Kyung-Shin Park and Henry N. Williford

The purpose of this study was twofold: 1) compare body volume (BV) estimated from dual energy X-ray absorptiometry (DXA) to BV from a criterion underwater weighing (UWW) with simultaneous residual lung volume (RLV), and 2) compare four-compartment (4C) model body fat percentage (BF%) values when deriving BV via DXA (4CDXA) and UWW (4CUWW) in physically active men and women. One hundred twenty-two adults (62 men and 60 women) who self-reported physical activity levels of at least 1,000 MET·min·wk-1 volunteered to participate (age = 22 ± 5 years). DXA BV was determined with the recent equation from Smith-Ryan et al. while criterion BV was determined from UWW with simultaneous RLV. The mean BV values for DXA were not significant compared with UWW in women (p = .80; constant error [CE] = 0.0L), but were significantly higher in the entire sample and men (both p < .05; CE = 0.3 and 0.7L, respectively). The mean BF% values for 4CDXA were not significant for women (p = .56; CE = –0.3%), but were significantly higher in the entire sample and men (both p < .05; CE = 0.9 and 2.0%, respectively). The standard error of estimate (SEE) ranged from 0.6–1.2L and 3.9–4.2% for BV and BF%, respectively, while the 95% limits of agreement (LOA) ranged from ±1.8–2.5L for BV and ±7.9–8.2% for BF%. 4CDXA can be used for determining group mean BF% in physically active men and women. However, due to the SEEs and 95% LOAs, the current study recommends using UWW with simultaneous RLV for BV in a criterion 4C model when high individual accuracy is desired.

Restricted access

Alistair R. Mallard, Rebecca T. McLay-Cooke and Nancy J. Rehrer

Effects of protein versus mixed macronutrient supplementation on total energy intake (TEI) and protein intake during an ad libitum diet were examined. Trained males undertook two, 2-week dietary interventions which were randomized, double blinded, and separated by 2 weeks. These were high-protein supplementation (HP: 1034.5 kJ energy, 29.6 g protein, 8.7 g fat and 12.3 g CHO) and standard meal supplementation (SM: 1039 kJ energy, 9.9 g protein, 9.5 g fat, and 29.4 g CHO) consumed daily following a week of baseline measures. Eighteen participants finished both interventions and one only completed HP. TEI (mean ± SD) was not different between baseline (11148 ± 3347 kJ) and HP (10705 ± 3143 kJ) nor between baseline and SM (12381 ± 3877 kJ), however, TEI was greater with SM than HP (923 ± 4015 kJ p = .043). Protein intake (%TEI) was greater with HP (22.4 ±6.2%) than baseline (19.4 ± 5.4%; p = .008) but not SM (20.0 ± 5.0%). No differences in absolute daily protein intake were found. Absolute CHO intake was greater with SM than HP (52.0 ± 89.5 g, p = .006). No differences in fat intake were found. Body mass did not change between baseline (82.7 ± 11.2 kg) and either HP (83.1 ± 11.7 kg) or SM (82.9 ± 11.0 kg). Protein supplementation increases the relative proportion of protein in the diet, but doesn’t increase the absolute amount of total protein or energy consumed. Thus some compensation by a reduction in other foods occurs. This is in contrast to a mixed nutrient supplement, which does not alter the proportion of protein consumed but does increase TEI.

Restricted access

Eirini Manthou, Jason M.R. Gill and Dalia Malkova

Background:

This study investigated health-related effects of exercise programs with exercise sessions of similar intensity but different frequency and duration.

Methods:

Thirty-four overweight women were randomized into either long-bout (LB) or short-bout (SB) exercise groups. Participants performed an 8-week supervised program, with the LB group exercising for 75 minutes twice per week, and the SB group for 30 minutes on 5 days of the week.

Results:

The LB group completed 16 sessions at a heart rate (HR) of 127 ± 1 beat·min−1 and the SB group completed 40 sessions at a HR of 126 ± 1 beat·min−1. Weekly energy expenditure of exercise was not different between groups (LB group, 5.64 ± 0.34 MJ; SB group, 5.83 ± 0.23 MJ). Training significantly (P < .05) increased measures of cardiorespiratory fitness, decreased waist circumference, insulin resistance, and diastolic blood pressure. The group × time interaction was not significant for any of these factors, indicating that responses to exercise training did not differ between the SB and LB groups.

Conclusions:

Health-related outcomes of exercise programs with similar energy expenditure are independent of frequency and duration of exercise sessions. This provides individuals with a degree of flexibility in exercise program planning.