Body composition and cross-sectional areas of limb lean tissues in Olympic weight lifters

The path less traveled: Using structural equation modeling to investigate factors influencing bone functional morphology

OBJECTIVES

The relationship between an organism's mechanical environment and its bone strength has been long established by experimental research. Multiple intrinsic and extrinsic factors, including body mass, muscle strength, genetic background, and nutritional and/or hormonal status, are likely to influence bone deposition and resorption throughout the lifespan, complicating this relationship. Structural equation modeling (SEM) is uniquely positioned to parse this complex set of influences.

MATERIALS AND METHODS

Data from the Third National Health and Nutrition Examination Survey, including sex, total body mass, lean body mass, exercise frequency, peak body mass, and age, were analyzed using SEM to determine how they affect bone strength both individually and combined.

RESULTS

Body mass is typically the driver of cross-sectional area, but body mass and lean mass have similar effects on the polar moment of area (J). Peak body mass had a strong direct effect on J, despite decreasing strongly with increases in lean mass. Exercise also did not confer a large direct effect on cross-sectional area or J but did modify body mass and lean mass. In females, intentional weight loss was associated with decreased exercise levels.

DISCUSSION

SEM is a useful tool for parsing complex systems in bone functional morphology and has the potential to uncover causal links in the study of skeletal remodeling, including factors like weight loss or exercise that may have secondary effects.

Profile of regional fat and fat-free soft tissue accumulation in male athletes

Background

It is unclear whether or not the breakpoint (BP), at which the proportion of each of fat mass (FM) and fat-free soft tissue mass (FFSTM) to body mass (BM) alter, exists in male athletes. We examined the hypothesis that in male athletes, the regional FM and FFSTM-BM relationships have a BP, but the body mass at BP (BM_BP) differs among the arms, trunk, and legs.

Methods

By using a dual X-ray absorptiometry, whole-body and regional FMs and FFSTMs in the arms, trunk, and legs were estimated in 198 male athletes (20.8 ± 2.1 years; 1.73 ± 0.07 m; 72.7 ± 14.8 kg). To detect the BP in the relationship between each of FM and FFSTM and BM, a piecewise linear regression analysis was used. If a BP was detected in the corresponding relationship, the significant difference between the regression slopes above and below the BP was examined.

Results

The regression analysis indicated that the BM_BP existed in the FM- and FFSTM-BM relationships regardless of region and whole body. For the whole body, BM_BP was 81.8 kg for FM and 82.2 kg for FFSTM. In regional FM-BM relationships, BM_BP was 80.5 kg for arms, 82.6 kg for trunk, and 63.3 kg for legs, and the regression slopes above the BM_BP became higher than those below the BP, and vice versa in regional FFSTM-BM relationships (BM_BP 104.6 kg for arms, 80.9 kg for trunk, and 79.0 kg for legs). The relative differences in the slopes between below and above BM_BP in the regional FM-BM relationships were higher in the arms and trunk than in the legs, and those in the regional FFSTM-BM relationships in the legs than in the trunk.

Conclusion

Whole-body and regional FM- and FFSTM-BM relationships for male athletes have breakpoints at which the proportion of the tissue masses to BM alters. The BM_BP and differences in the distribution of regional FM and FFSTM around the breakpoint are region specific.

Effects of squat training with different depths on lower limb muscle volumes

PURPOSE

The purpose of this study was to compare the effects of squat training with different depths on lower limb muscle volumes.

METHODS

Seventeen males were randomly assigned to a full squat training group (FST, n = 8) or half squat training group (HST, n = 9). They completed 10 weeks (2 days per week) of squat training. The muscle volumes (by magnetic resonance imaging) of the knee extensor, hamstring, adductor, and gluteus maximus muscles and the one repetition maximum (1RM) of full and half squats were measured before and after training.

RESULTS

The relative increase in 1RM of full squat was significantly greater in FST (31.8 ± 14.9%) than in HST (11.3 ± 8.6%) (p = 0.003), whereas there was no difference in the relative increase in 1RM of half squat between FST (24.2 ± 7.1%) and HST (32.0 ± 12.1%) (p = 0.132). The volumes of knee extensor muscles significantly increased by 4.9 ± 2.6% in FST (p < 0.001) and 4.6 ± 3.1% in HST (p = 0.003), whereas that of rectus femoris and hamstring muscles did not change in either group. The volumes of adductor and gluteus maximus muscles significantly increased in FST (6.2 ± 2.6% and 6.7 ± 3.5%) and HST (2.7 ± 3.1% and 2.2 ± 2.6%). In addition, relative increases in adductor (p = 0.026) and gluteus maximus (p = 0.008) muscle volumes were significantly greater in FST than in HST.

CONCLUSION

The results suggest that full squat training is more effective for developing the lower limb muscles excluding the rectus femoris and hamstring muscles.

Ten-second maximal pedaling power as a representative measure for assessing sprint performance

BACKGROUND

There is no evidences concerning the relative contribution of physiological parameters to maximal sprinting velocity and acceleration ability. The aim of this study is to elucidate the associations between physiological variables and sprint performance.

METHODS

Twenty-six male sprinters performed a 60-m sprint twice. Maximal sprint velocity (Vmax) and running distance after 4 s from the start (D4) were measured as indices of sprint performance during the sprint using a laser distance measurement device. Body composition, jump performance in the countermovement jump, the rebound jump, the standing long jump and the standing 5-step jump, and 10-s maximal anaerobic pedaling power were measured as physiological variables.

RESULTS

All measured variables were significantly related to Vmax (r=0.49-0.71, P<0.05) and D4 (r=0.39-0.72, P<0.05), expect for anthropometric variables. Multiple regression analysis indicated that the 10-s maximal anaerobic pedaling power relative to body mass was the only variable that significantly explained Vmax and D4.

CONCLUSIONS

The 10-s maximal anaerobic pedaling power relative to body mass can be a representative measure for assessing the sprint performance of male sprinters.

Body shape indices are predictors for estimating fat-free mass in male athletes

It is unknown whether body size and body shape parameters can be predictors for estimating whole body fat-free mass (FFM) in male athletes. This study aimed to investigate whether body size and shape variables can be predictors for FFM in male athletes. Using a whole-body dual-energy X-ray absorptiometry scanner, whole body fat mass (FM) and FFM were determined in 132 male athletes and 14 sedentary males. The sample was divided into two groups: validation (N = 98) and cross-validation (N = 48) groups. Body height (BH), body mass (BM), and waist circumference at immediately above the iliac crest (W) were measured. BM-to-W and W-to-BH ratios were calculated as indices of body shapes. Stepwise multiple regression analysis revealed that BM/W and W/BH were selected as explainable variables for predicting FFM. The equation developed in the validation group was FFM (kg) = 0.883 × BM/W (kg/m) + 43.674 × W/BH (cm/cm)- 41.480 [R2 = 0.900, SEE (%SEE) = 2.3 kg (3.8%)], which was validated in the cross-validation group. Thus, the current results demonstrate that an equation using BM/W and W/BH as independent variables is applicable for predicting FFM in male athletes.

A protocol for a randomised controlled trial of the bone response to impact loading or resistance training in young women with lower than average bone mass: the OPTIMA-Ex trial

INTRODUCTION

The aim of the Osteoporosis Prevention Through Impact and Muscle-loading Approaches to Exercise trial is to compare the bone response to two known osteogenic stimuli - impact loading exercise and resistance training. Specifically, we will examine the effect of a 10-month, twice-weekly, high-intensity impact loading exercise intervention and a 10-month, twice-weekly, high-intensity resistance training intervention on bone mass and strength at clinically important skeletal sites. The intervention groups will be compared against a home-based 'positive' control group. Safety and acceptability of each exercise modality will also be determined.

METHODS AND ANALYSIS

Sedentary otherwise healthy young women aged 18-30 years with bone mineral density (BMD) T-scores less than or equal to 0 at the hip and lumbar spine, screened for conditions and medications that influence bone and physical function, will be recruited. Eligible participants are randomised to 10-month, twice-weekly, either supervised high-intensity impact training, high-intensity resistance training or a home-based 'positive' control group. The primary outcome measure will be lumbar spine areal BMD, while secondary outcome measures will include: whole body, femoral neck and regional measures (upper and lower limb) of bone, muscle and fat; anthropometrics; muscle strength and power; quality of life and exercise safety, enjoyment and acceptability. All outcome measures will be conducted at baseline (T0) and 10 months (T10) and will be analysed according to the intention-to-treat principle and per protocol.

ETHICS AND DISSEMINATION

The study has been granted ethical approval from the Griffith University Human Research Ethics Committee (GU Ref: 2015/775). Standard scientific reporting practices will occur, including publication in peer-reviewed journals. Participant confidentiality will be maintained in all forms of reporting.

TRIAL REGISTRATION NUMBER

ACTRN12616001444471.

Body composition and endocrine profile of male Olympic athletes striving for leanness

OBJECTIVE

To investigate the endocrine profile, body composition, and state of mood in male Olympic athletes participating in sports that do or do not emphasize leanness.

DESIGN

Cross-sectional study.

SETTING

Research unit at a university hospital.

PARTICIPANTS

Forty-four Swedish male Olympic athletes participating in 26 different sport disciplines.

MAIN OUTCOME MEASURES

Body composition was determined by dual-energy x-ray absorptiometry, and blood levels of steroid hormones and biomarkers of nutritional status were analyzed. In addition, states of mood were assessed employing the profile of mood states (POMS) test. The athletes were divided into 2 groups on the basis of whether their sporting discipline emphasized leanness or not.

RESULTS

In all subjects, body composition, hormone levels, and POMS scores were within normal ranges. However, the leanness athletes (n = 18) displayed significantly lower proportion of body fat (P < 0.01), higher spinal bone mineral density (P < 0.05), lower serum levels of free testosterone and leptin (P < 0.05), and higher serum levels of insulin-like growth factor binding protein 1 (P < 0.05) than nonleanness athletes (n = 26). Leanness athletes also had higher POMS scores for depression and anger, and a higher global POMS score (P < 0.05), the latter being positively correlated to the frequency of illness (r = 0.42, P < 0.01) before the Olympic Games.

CONCLUSION

Although there were no indications of energy deficiency or endocrine disturbance in the leanness athletes, their higher POMS scores and frequency of illness may indicate the potential harmfulness of their pursuit of outstanding athletic performance.

Event-related differences in the cross-sectional areas and torque generation capabilities of quadriceps femoris and hamstrings in male high school athletes

This study investigated the event-related differences in the cross-sectional areas (CSAs) and torque generation capabilities of the quadriceps femoris (QF) and hamstrings (HAM) in male high school athletes. Subjects were soccer players (n=32), volleyball players (21), rowers (29), karate athletes (18), sumo wrestlers (15), sprinters (22), throwers (16), and nonathletes (20). The CSAs of QF and HAM at the mid-thigh were determined using magnetic resonance imaging. In addition, isokinetic torques during knee extension and flexion were determined at a pre-set velocity of 1.05 rad/s. The CSAs of the two muscle groups and torques developed in the two motions were significantly related to the two-third power of lean body mass (LBM(2/3)) and the product of CSA and femur length (CSA*fl), calculated as an index of muscle volume, respectively. CSA relative to LBM(2/3) for QF did not differ among the groups, but that for HAM was higher in sprinters, soccer players, throwers, and karate athletes than in sumo wrestlers, rowers, volleyball players, and nonathletes. Knee extension torque relative to the CSA*fl of QF was higher in karate athletes, soccer players, and rowers than in nonathletes, but the corresponding value for knee flexion did not differ among groups. Thus, the present study indicated that, at least in male high school athletes, the event-related differences in LBM and the muscularity of QF and HAM produced the corresponding differences in the CSAs of the reciprocal muscle groups and knee extension and flexion torques, respectively. However, specific profiles related to competitive and/or training styles exist in HAM CSA and knee extension torque, which cannot be explained by the magnitude of LBM and QF CSA, respectively.

Effects of electrical stimulation on muscle trophism in patients with hemophilic arthropathy

OBJECTIVE

To determine changes occurring in the cross-sectional area, electromyography (EMG) activity, and the strength of the biceps brachii after an 8-week period of bilateral training with surface muscle electrical stimulation in patients with hemophilic arthropathy.

DESIGN

Controlled trial.

SETTING

Coagulopathy unit, university hospital.

PARTICIPANTS

Volunteer subjects (N=30) participated in this study: 15 with severe hemophilia A (hemophilic group) and 15 nonhemophilic control subjects (control group).

INTERVENTIONS

The hemophilic group followed a surface electrical stimulation program (frequency 45 Hz, impulse 200 micros, 10s on/10s off) over an 8-week period on the biceps brachii of both arms. The control group did no training of any kind.

MAIN OUTCOME MEASURES

The cross-sectional area, maximum voluntary isometric contraction, and EMG activity of the biceps brachii in both arms were determined before and after the 8-week-long task.

RESULTS

The results of the hemophilic group showed significant increases in the diameter (15.8%, P<.001), isometric force (4.6%, P<.05), and EMG activity (37.6%, P<.05) of the biceps brachii muscles in both arms. No significant changes were observed for the control group.

CONCLUSIONS

Our findings confirm the efficacy of muscle electrical stimulation in causing muscles to hypertrophy in patients with hemophilia, thereby improving their muscular strength. In addition, these results may also be clinically applicable in the rehabilitation of patients who have similar deficiencies in the locomotor system.

Knee cartilage morphologic characteristics and muscle status of professional weight lifters and sprinters: a magnetic resonance imaging study

BACKGROUND

Whereas muscle and bone mass have been shown to strongly depend on mechanical stimulation (loading history), this relationship has not been established for articular cartilage.

HYPOTHESIS

Subjects with high muscle strength display thicker knee cartilage and larger joint surface areas than nonathletic volunteers, and knee cartilage morphologic characteristics correlate more strongly with muscle force than with muscle cross-sectional areas.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Fourteen young, healthy adult professional athletes (7 weight lifters and 7 bobsled sprinters) were examined and compared with 14 adult nonathletic volunteers who had never performed strength training. Muscle moments were measured with a dynamometer and muscle cross-sectional areas and knee cartilage morphologic characteristics with magnetic resonance imaging.

RESULTS

Weight lifters and sprinters displayed significantly (P < .001) larger extensor muscle moments and cross-sectional areas. They showed significantly greater (P < .01) patellar cartilage thickness than nonathletic volunteers (+14% [95% confidence interval, 6% to 22%] and +17% [95% confidence interval, 9% to 26%], respectively) but no significant differences in the cartilage thickness of the other knee joint cartilage plates or joint surface areas. Muscle moments did not correlate more strongly with knee cartilage volume or thickness than muscle cross-sectional areas of the thigh.

CONCLUSIONS

Direct measurements of muscle forces do not predict cartilage thickness more accurately than muscle cross-sectional areas. These findings suggest that cartilage thickness has much less ability, if any, to adapt to mechanical loading than muscle. Large cohorts of athletes will need to be studied to detect potentially significant differences in cartilage versus nonathletic controls.